,transcriber's ,notes ,italic text is displayed as3 italic ,bold text is displayed as3 bold ,,motor-,,car ,,principles ,,motor-,,car ,,principles ,,the ,,gasoline ,,automobile ,,by ,,roger ,b4 ,,whitman ,,illustrated ,illustration3 ,decoration ,,new ,,and ,,enlarged ,,edition ,d4 ,,appleton ,,and ,,company ,,new ,,york1 ,,london ,,mcmx ,,copyright1 #aijg1 #aiji1 ,,by ,d4 ,,appleton ,,and ,,company ,,introduction ,the development of the gasoline automobile at home and abroad has produced a great variety of designs1 good1 bad1 and indifferent1 but the advancement of the industry has weeded out the unsatisfactory and improved the good until with few exceptions the leading makes show a striking similarity in all but details4 ,the advantages of certain forms of construction have been recognized1 and their adoption by the large majority of makers has produced what may be called a standard type4 ,the object of this book is to explain the principles that underlie automobile construction and operation1 and to illustrate the movements and mechanical combinations adopted in present-day practice4 ,it is not the intention to explain the exact details of construction of the different cars1 and the illustrations have been prepared with the sole object of making the principles clear1 for with an understanding of these there should be no difficulty in comprehending any particular application of them4 ,the lubrication table on pages #bdd and #bde1 which was prepared by ,mr4 ,t4 ,d4 ,hanauer1 is reproduced through the courtesy of the ,scientific ,american4 99 99 99 99 99 ,the advantages of magneto ignition for internal combustion engines are so obvious that designers and inventors have directed their attention to the perfection of apparatus that will improve present methods4 ,the number of systems proposed for the purpose is very large in comparison with the number in actual and practical use1 and as in a work of this size it would be impossible to describe the many methods for the application of the magneto that are on the market1 attention has been given only to those that are in actual1 everyday use4 ,the absence of a practical treatise on the principles1 application1 and care of low and high tension magnetos is the reason for the addition of the appendix to this work4 ,r4 ,b4 ,w4 ,,contents ,,chapter ,i ,,gasoline-,,engine ,,principles ,,pages ,properties of gases--,steam-engine principles--,gasoline-engine principles--,combustion and explosion--,events of cycle--,four-cycle and two-cycle engines--,strokes of cycle--,fly wheel--,valves--,inlet stroke--,inlet valve closing--,compression-combustion stroke--,advantages of compression--,instant of ignition--,advancing and retarding ignition--,limit of compression--,power stroke--,heat losses--,opening of exhaust valve--,exhaust stroke--,clearance--,back pressure--,steam and ,gasoline engines compared--,gasoline--engine power #a-ai ,,chapter ,,ii ,,engine ,,parts ,crank shaft--,crank-shaft bearings--,relative position of cranks--,connecting rod--,wrist pin--,piston and piston rings--,automatically and mechanically operated valves--,cams and cam shaft--,secondary shaft--,two-to-one gears--,valve-lifter rod--,valve locations--,muffler--,engine cooling--,cooling by ,water--,pumps--,radiators--,pressure and gravity systems--,cooling by air--,lubrication #bj-cf ,,chapter ,,iii ,,engine ,,balance ,vibrations of engine--,one-cylinder engine--,horizontal double-opposed--,two-cylinder vertical--,four-cylinder--,firing order--,balance of three- and six-cylinder engines--,comparison of engine types #cg-df ,,chapter ,,iv ,,two-,,cycle ,,engines ,principle--,construction--,ports--,cycl e--,action--,advantages and disadvantages #dg-ea ,,chapter ,v ,,carburetion ,,and ,,gasoline ,,feeds ,carburetion--,carburetor--,carburetor parts--,carburetor action--,necessity for auxiliary air--,auxiliary air inlet--,automatic and mechanically controlled air inlet--,carburetors with side and central mixing chambers--,mechanically controlled carburetor--,surface carburetors--,gravity feed--,pressure feed--,check and relief valve #eb-gc ,,chapter ,,vi ,,ignition ,ignition system--,electric current--,parts of ignition system--,flow of current--,conductors and insulators--,resistance--,measurements of current--,lead and return wires--,grounding the return--,generators--,dry cell--,storage cell--,electrolyte--,hydrometer--,batter y connections3 series1 parallel and multiple--,magnetism--,magnets--,magneti c lines of force--,magnetic field--,field and armature--,magneto and dynamo--,switch--,switch parts #gd-ij ,,chapter ,,vii ,,ignition--7,continued7 ,ignition systems--,make-and-break system--,igniter--,tappet--,connections- -,primary induction coil--,action of coil--,induced current--,magneto--,jump-spark system--,secondary induction coil--,primary and secondary circuits--,timers--,mechanical and magnetic vibrators--,spark plug--,circuit--,condenser--,secondary distributer #ia-aaa ,,chapter ,,viii ,,transmission ,transmission parts--,clutches--,friction-cone clutch--,reversed friction-cone clutch--,multiple disk clutch--,internal expanding clutch--,change-speed mechanisms--,sliding gear3 progressive and selective types--,use of clutch in changing gear #aab-aca ,,chapter ,,ix ,,transmission--7,continued7 ,planetary type of change-speed mechanism--,individual clutch--,friction type--,final drive--,turning the direction of the power--,bevel gears--,single-chain drive--,propeller-shaft drive--,universal joints--,live axle--,floating axle--,torsion rod--,double-chain drive--,jack shaft--,differential--,bevel-gear differential--,spur-gear differential--,driving-gear ratios #acb-afj ,,chapter ,x ,,running ,,gear ,steering--,front axle--,steering knuckles and arms--,drag link--,steering principles--,steering mechanisms--,brakes3 contracting and expanding--,brakes3 single- and double-acting--,running brake--,emergency brake--,engine as a brake--,brake equalizer--,tires--,tire construction--,tire inflation--,skidding--,antiskid devices--,springs--,shock absorbers--,distance rods #afa-agh ,,chapter ,,xi ,,troubles ,ignition--,circuit--,battery--,magneto- -,coil--,spark plug--,igniter--,timer--,secondary distributer--,switch--,gasoline--,tank-- ,carburetor--,compression-- ,cooling--,freezing--,lubrication #agi-bjb ,,chapter ,,xii ,,locating ,,trouble ,make-and-break ignition--,jump-spark ignition--,carburetor--,engine will not start--,engine will not deliver full power--,weak explosions--,missing explosions--,missing at high speed--,engine starts well1 but comes to a stop--,overheating--,engine comes to a stop--,noises #bjc-bai ,,chapter ,,xiii ,,maintenance ,,and ,,construction ,inspection--,washing the car--,tires--,care of the engine--,care of the chains--,valve grinding--,care of the steering mechanism--,care of the springs--,adjusting the vibrators--,matching coils--,adjusting the carburetor--,setting the valves--,ignition wiring #bbj-bdb ,,lubrication ,,table #bdd-bde ,,appendix ,magnetism--,induction--,magneto principles--,general magneto troubles--,low tension ignition system--,setting up1 care and troubles--,low tension magneto with secondary coil--,direct high tension magneto--,bosch two-spark magneto--,bosch four-spark magneto--,dual systems--,magnetic plug ignition--,inductor magnetos #bdg-cbf ,,testing ,,chart ,between #cbf and #cbg ,,index #cbg-cci ,,list ,,of ,,illustrations ,,fig4 ,,page #a4 ,engine ,actions #c #b4 ,gasoline ,engine ,cycle #g #c4 ,gasoline ,engine in ,section #ba #d4 ,crank ,shafts #bb #e4 ,one-,throw ,crank ,shaft #bc #f4 ,connecting ,rod #bc #g4 ,piston and ,piston in ,section #bd #h4 ,piston ,rings #bd #i4 ,conical ,valve ,seat #be #aj4 ,automatic ,inlet ,valve in ,cage #be #aa4 ,cam ,action #bg #ab4 ,four ,arrangements of ,valves #bi #ac4 ,circulation of ,cooling ,water #ca #ad4 ,types of ,pumps #cb #ae4 ,radiator ,constructions #cc #af4 ,radiator and ,fan #cc #ag4 ,engine ,arrangements ,showing ,order of ,firing #dj #ah4 ,two-,cycle ,engine #dh #ai4 ,carburetor ,principles #ed #bj4 ,automatic ,carburetors #ei #ba4 ,mechanically ,controlled ,carburetor #fc #bb4 ,float-,feed ,carburetor with ,gravity ,gasoline ,feed #fe #bc4 ,pressure-,feed ,gasoline ,system #fg #bc;,a4 ,types of ,float ,valves #fi #bc;,b4 ,types of ,auxiliary ,air ,inlets #ga #bd4 ,battery ,connections #he #be4 ,make-and-,break ,ignition #ib #bf4 ,types of ,timers #ii #bg4 ,mechanical ,vibrator #ajd #bh4 ,magnetic ,vibrator #ajd #bi4 ,spark ,plug and ,spark ,plug in ,section #ajg #cj4 ,ignition ,circuit #ajh #ca4 ,friction ,cone ,clutches #aae #cb4 ,multiple-,disk ,clutch #aag #cc4 ,sliding ,gear--,progressive ,type #abb #cd4 ,selective ,type #abg #ce4 ,planetary ,type #acc #cf4 ,individual ,clutch and ,friction ,drive #aci #cg4 ,propeller and ,single-,chain ,drives #adc #ch4 ,typical ,universal ,joint #add #ch;,a4 ,types of ,shaft ,drives #ade #ci4 ,live ,axle--,non-floating ,type #adg #dj4 ,live ,axle--,floating ,type #adg #dj;,a4 ,dead ,axle with ,driving ,shaft #adi #da4 ,torsion ,rod #aej #db4 ,double ,side-,chain ,drive #aea #dc4 ,differentials #aed #dd4 ,two ,arrangements of the ,drag ,link #afb #de4 ,steering ,principles #afc #df4 ,steering ,mechanisms #afe #dg4 ,three ,varieties of ,brakes #afh #dh4 ,springs #age #di4 ,distance or ,radius ,rods #agg #ej4 ,jump-,spark ,wiring ,diagrams #bcg #ea4 ,jump-,spark ,wiring ,diagrams #bci #eb4 ,make-and-,break ,wiring ,diagram #bda #ec4 ,make-and-,break ,wiring ,diagram #bda ,,illustrations ,,in ,,appendix #a4 ,magnetic ,lines of ,force #bej #b4 ,armature #bef #c4 ,the ,armature and ,lines of ,force #bef #d4 ,the ,armature and ,lines of ,force #beg #e4 ,the ,armature and ,lines of ,force #beg #f4 ,the ,armature and ,lines of ,force #beh #g4 ,the ,armature and ,lines of ,force #bei #h4 ,make-and-,break ,system #bga #i4 ,eisemann ,ignition ,system #bhe #aj4 ,wiring ,diagram1 ,h4-,t4 ,magneto ,interchangeable with ,secondary ,coil #bih #aa4 ,wiring ,diagram1 ,two-,spark ,magneto #cjb #ab4 ,timing ,diagram1 ,two-,spark ,magneto #cjd #ac4 ,diagrams showing ,position of ,shield ,revolving about ,armature #cji #ad4 ,wiring ,diagram1 ,four-,spark ,magneto #cab #ae4 ,timing ,diagram1 ,four-,spark ,magneto #cad #af4 ,bosch ,jump-,spark ,dual ,system #cah #ag4 ,remy ,inductor #cba #ah4 ,inductor ,giving ,six ,waves #cba #ai4 ,magnetic ,igniter #cbd #bj4 ,wiring ,diagram of ,magnetic ,igniter ,system #cbd ,,motor-,,car ,,principles ,,chapter ,i ,,gasoline ,,engine ,,principles ,the action of a steam1 gasoline1 or hot-air engine depends on the principle that when air or other gas is heated it expands1 and that if it is confined in a space that will not permit it to expand1 in striving to do so it creates pressure against all parts of the chamber in which it is contained4 ,the more a gas is heated1 the more it will expand if it is free to do so1 and if not free1 the greater will be the pressure that it will exert in striving to expand4 ,pressure may thus be generated by heat1 and following along similar lines1 heat may be produced by pressure1 for when the pressure of a gas is increased by compressing it1 or forcing it to occupy a smaller space1 the gas will become heated4 ,the reverse is also true1 that when a gas is cooled1 its volume is reduced1 which reduces the pressure that it exerts2 similarly1 reducing the pressure by permitting the gas to expand reduces its temperature4 ,to state these principles in another form1 to create pressure in a gas it must either be heated or compressed into a smaller space1 and to reduce its pressure it must either be cooled or permitted to expand4 ,the action of a locomotive1 the most familiar type of steam engine1 is no mystery1 and the production of steam in the boiler1 its passage to the cylinder1 and the application of its steady pressure against first one side of the piston and then the other1 resulting in the turning of the driving wheels1 are well understood4 ,water being converted into steam in the boiler1 pressure is created because of the tendency of the steam to expand1 but the only place in which it may expand is the cylinder1 where in so doing it moves the piston4 ,illustration3 ,,fig4 #a4--;,,engine ,,actions4 ,a gasoline engine is similar to a steam engine in that its piston is moved by the pressure exerted by a heated and expanding gas2 it is different in that the pressure is produced inside of the cylinder by the combustion of an inflammable mixture of gasoline vapor1 instead of being generated in a boiler away from the cylinder4 ,the heat of the combustion creates great pressure1 and as the piston is the only part that can give before it1 it is moved from one end of the cylinder to the other1 this motion being utilized in the turning of the crank shaft4 ,the combustion1 which is so rapid that the generally accepted term for it is explosion1 can occur only after the mixture has been drawn into the cylinder1 and so prepared that it ignites quickly and burns completely1 with the object of obtaining the greatest possible heat from it in the shortest possible time4 ,in order that one explosion may be followed by another1 the burned and useless products of combustion must be expelled to make place for a fresh charge of the inflammable mixture4 ,these successive events1 forming a cycle1 must be performed as long as the engine runs1 and the constantly changing pressure in the cylinder due to the movement of the piston allows a fresh charge to enter1 prepares it1 and expels the products of combustion after the pressure that they have exerted has been utilized4 ,while in the great majority of steam engines the steam acts first on one side of the piston and then on the other1 in an automobile gasoline engine the pressure is exerted on only one side1 the combustion of the mixture taking place between the piston and the closed end1 or head1 of the cylinder4 ,the other end of the cylinder is open1 and the piston slides between the ends1 its movement from one end to the other1 called a stroke1 corresponding to a half revolution of the crank shaft4 ,gasoline engines are divided into two classes1 according to the number of strokes of the piston that are necessary to accomplish the cycle2 in the most usual type1 four strokes are necessary1 the class being called the four-stroke-cycle1 or four-cycle1 in distinction to the two-stroke-cycle1 or two-cycle1 in which but two strokes are necessary4 ,of the five events that compose the cycle1 three 7the inlet1 during which the fresh mixture enters the cylinder1 its compression or preparation1 and the exhaust of the burned gases7 are performed by the piston2 during the power event the piston is moved by the pressure resulting from the combustion1 while the combustion event is due to an outside source4 ,in the four-cycle type of engine1 which is in almost universal use for automobiles1 the events are considered with reference to the movement made by the piston during which they are performed1 and may be called the inlet1 compression-combustion1 power1 and exhaust strokes4 ,in order that the engine may continue to run1 it is obvious that the events must be performed in the correct order1 and that the failure of one will affect all the others4 ,during the inlet stroke1 a charge of fresh mixture enters the cylinder as the piston makes an outward stroke from the closed toward the open end4 ,when the piston makes the following inward stroke1 the mixture is compressed and combustion occurs1 the pressure from which drives the piston outward on the power stroke4 ,this is followed by another inward stroke1 which pushes the burned gases out of the cylinder4 ,it will be seen that power is developed during only one stroke of the four1 the other three being required in the preparation for the following power stroke4 ,the movement of the piston over these three dead strokes is secured by attaching to the crank shaft a heavy fly wheel1 the momentum of which1 acquired during the power stroke1 keeps the crank shaft revolving and the piston in motion while the events are performed4 ,illustration3 ,,suction ,,stroke ,,compression ,,stroke ,,power ,,stroke ,,exhaust ,,stroke ,,fig4 #b4--;,,gasoline ,,engine ,,cycle4 ,the space between the piston and cylinder head in which the combustion occurs is called the combustion space1 and the inlet and exhaust valves open into it1 the first being that by which the fresh mixture enters1 and the second that by which the products of combustion escape4 ,the device for igniting the mixture projects into the combustion space1 and the means of ignition in universal use for automobile engines is an electric spark4 ,,inlet ,,stroke ,during the stroke 7,fig4 #b71 the piston is moved outward by the crank shaft1 which is revolved either by hand or by the momentum of the fly wheel4 ,this movement increases the size of the combustion space1 thereby reducing the pressure in it1 and the higher pressure of the atmosphere outside of the cylinder will force fresh mixture into the combustion space1 the inlet valve being open to admit it4 ,if the piston moves slowly1 the mixture will be able to enter fast enough to keep the pressure in the combustion space equal to that outside1 but at the high speed at which a gasoline engine is run the piston will reach the end of its stroke before a complete charge has had time to enter1 so that the pressure in the combustion space will still be below that of the atmosphere4 ,if the inlet valve closed at this point so that no more mixture could enter1 the combustion of the partial charge would result in a lower pressure than would be possible with a full charge2 the inlet valve should therefore remain open until the piston reaches the point of its next inward stroke at which the pressure in the cylinder equals that outside4 ,,compression-,,combustion ,,stroke ,the compression and the combustion of the charge occur during the next inward stroke of the piston4 ,the period between the bringing together of the liquid gasoline and air and its admission to the cylinder is too brief to secure perfect combination1 and the mixture that results is not satisfactory4 ,a portion of the air will not have been able to come into contact with the gasoline1 and much of the liquid will not have been vaporized2 what passes into the cylinder consists of pure air1 liquid gasoline1 and a more or less perfect mixture of the two4 ,the combustion of this would be slow and incomplete1 resulting in loss of power and waste of fuel4 ,in order to render the mixture more perfect1 advantage is taken of the heat that is produced by compression2 the inward stroke of the piston raises the temperature of the mixture by compressing it1 the heat rendering the gasoline more volatile1 and the compression forcing it into combination with the air4 ,even this does not result in the formation of a perfect mixture1 for the period is too short to effect it4 ,the failure of an engine to deliver full power may often be traced to this condition1 for the air and gasoline vapor1 instead of being thoroughly combined and mixed1 will be in layers1 so to speak1 and the combustion will be slow and uneven4 ,future development of the internal combustion engine will no doubt eradicate this1 to the increase of efficiency and economy4 ,the charge of inflammable mixture can produce a certain amount of heat1 and the more rapidly and completely this heat is obtained1 the greater and more sudden will be the rise in pressure4 ,the pressure will be greater when the mixture is contained in a small space than when in a large1 and as the combustion space is smallest when the piston is at its inmost point1 the greatest pressure will be obtained if combustion is complete at this point4 ,if the combustion of the mixture were instantaneous1 it should be ignited at this point2 but even though very rapid1 it nevertheless burns slowly enough to make it necessary to ignite it sufficiently before the end of the stroke to have the combustion complete as the piston comes into position to move outward4 ,the instant at which the mixture must be ignited in order to produce this result depends on the speed of the piston1 for the interval between the ignition of a good mixture and its complete combustion does not vary to any great extent4 ,when the piston is moving slowly1 the mixture may be ignited toward the end of the compression stroke1 for there will be sufficient time for complete combustion by the time the stroke is ended2 but when moving at high speed1 ignition must occur much earlier in the stroke1 as otherwise the piston will have completed the compression stroke and begun to move outward on the power stroke before the mixture is entirely burned4 ,the instant at which ignition occurs also depends on the mixture that is used1 for its quality and proper combination make a difference in the rapidity with which it burns4 ,the better the quality of the mixture1 the faster and more completely it will burn1 and ignition may occur later in the stroke than would be possible with a mixture of poor quality4 ,as the mixture is ignited by the passing of an electric spark in the combustion space1 the difference in the instant at which it occurs may be secured by permitting the spark to pass earlier or later1 and this is under the control of the driver4 ,when ignition occurs early in the compression stroke1 the spark is said to be advanced1 in distinction to a retarded spark1 which passes when the compression stroke is more nearly complete4 ,if the spark is advanced too much1 combustion will be complete before the piston has reached the end of the compression stroke1 and it will be necessary to force it to the end of the stroke against the pressure by the momentum of the fly wheel1 in order that it may get into position to move outward on the power stroke4 ,in such a case1 the momentum may not be sufficient to overcome the pressure1 and the piston will be brought to a stop4 ,a retarded spark results in the combustion of the mixture being completed after the piston has begun to move outward on the power stroke1 and the pressure will then be reduced because it is exerted in a larger space1 the piston consequently being moved with less force2 if the spark is still further retarded1 the combustion will not be complete by the time the exhaust begins1 and the heat from only a portion of the mixture will be utilized1 because it will still be burning as it is forced out of the cylinder4 ,the position at which the spark occurs is one of the means by which the speed of the engine is controlled1 for the low pressure that results from a retarded spark moves the piston at low speed1 while the greater pressure from an advanced spark drives the piston outward with more force and higher velocity4 ,while high compression of the charge improves its quality1 and results in combustion being more rapid and complete1 it has limits1 and if carried too far the heat generated by the compression will be sufficient to ignite the mixture4 ,this would have a bad effect on the operation of the engine1 for the pressure would then be produced at the wrong point of the stroke1 retarding instead of assisting the revolution of the crank shaft4 ,modern practice has shown that in engines that are maintained at a proper temperature the best results are obtained by compressing the mixture to from sixty to eighty pounds to the square inch2 there are instances in which a higher compression is obtained1 but the liability to ignite the mixture prematurely makes it undesirable4 ,,power ,,stroke ,the increasing size of the combustion chamber as the piston moves outward on the power stroke permits the gases to expand1 and in doing so the temperature will fall1 the pressure decreasing in consequence4 ,a further decrease in pressure is caused by the hot gases being in contact with the metal cylinder and piston1 which absorb heat4 ,the more slowly the engine runs1 the longer the gases will be in contact with the cylinder walls1 and the more opportunity there will be for loss of heat from this cause2 at higher speeds1 there will be less time for heat to be absorbed by the cylinder walls1 and more will be utilized in expanding the gases and producing work4 ,even at the outmost position of the piston1 the combustion space will not be large enough to permit the gases to expand until their pressure has dropped to that of the atmosphere1 so that they will still be exerting pressure4 ,by opening the exhaust valve1 the gases will have an outlet for expansion1 and will begin to rush out4 ,while the pressure might be utilized against the piston to the end of the power stroke1 it has been found that better results are obtained by opening the exhaust valve before the piston reaches the end of the power stroke4 ,there is then a higher pressure forcing the gases out than there would be later in the stroke1 and the greater quantity of gases that escapes leaves less to be expelled during the exhaust stroke4 ,,exhaust ,,stroke ,the inward movement of the piston pushes out of the open exhaust valve the gases that have not escaped through their desire to expand4 ,the exhaust valve remains open for the entire stroke1 but when the engine is running at high speed the piston moves so rapidly that the gases cannot escape fast enough to prevent their being slightly compressed4 ,when the piston is at its inmost point1 the gases are still flowing through the valve because of this slight compression1 and if the valve closed1 a portion would be retained4 ,the best results come from the closing of the exhaust valve not at the end of the exhaust stroke1 but a short time after the piston has begun to move outward again1 during which period the compression forces the gases out4 ,the exhaust valve closes at the point when the slight compression has been reduced to the pressure of the atmosphere by the escape of the gases and the enlargement of the combustion space4 ,if the piston completely filled the combustion space when at its inmost point1 all of the burned gases would be expelled1 but the necessity for leaving a space in which combustion may take place renders this impossible1 and a small portion of the burned gases therefore remains in the cylinder4 ,the space between the cylinder head and the piston when at its inmost point1 called the clearance1 should be as small as possible1 in order that the amount of these gases remaining in the cylinder may not be sufficient to contaminate the fresh charge and weaken the pressure of its combustion4 ,the passages through which the burned gases are led away from the cylinder must be large and free from obstructions1 for if a free flow is not permitted back pressure will be set up1 which will prevent the largest possible amount of gases from escaping1 and leave a greater portion to contaminate the fresh charge4 ,the power that a gasoline engine is capable of developing depends on the size of the cylinder1 the pressure acting on the piston1 and the speed at which it operates4 ,a steam engine1 which obtains its pressure from a boiler1 can do work as soon as the steam is turned into the cylinder1 but a gasoline engine must be running before it can be called on to deliver power4 ,because of the cycle of events on which its operation depends1 the piston must be forced to perform the inlet and compression strokes before pressure can be developed1 and it is necessary to revolve the crank shaft by outside means until a charge of mixture has been taken into the cylinder1 compressed1 and ignited1 when the engine begins to work by the pressure from the combustion1 and takes up its cycle4 ,not until this has been done can it be called on to do work4 ,a steam engine can be made to deliver more power than it is built for by increasing the pressure acting against its piston1 and the full pressure of the boiler can be utilized when extra work is necessary4 ,the power developed by a gasoline engine being greatly dependent on its speed1 and there being no reserve by which greater power can be developed in emergencies1 it is necessary for an engine of this type to be perfectly adapted to the work that is desired of it4 ,at excessive speeds the piston acquires great momentum1 which must be overcome at each end of a stroke by the crank shaft1 and while a speed above normal may be attained1 it results in the quick destruction of the bearings and the severe straining of the engine4 ,the best results in efficiency and long life accompany the running of the engine at the slowest speed possible for the development of the required power4 ,,chapter ,,ii ,,engine ,,parts ,the sudden and powerful outward movements of the piston under the pressure from the combustion are transmitted to a crank shaft1 which must be of great strength in order to resist the heavy strains under which it operates4 ,it is made of the best steel available for the purpose1 and has as many cranks as the engine has cylinders4 ,the cranks are generally made in one piece with the shaft for the sake of strength1 and for stiffness there are as many bearings as possible4 ,the number of bearings for the crank shaft of an engine with four or more cylinders depends on the arrangement of the cylinders4 ,if the cylinders are evenly spaced1 there will be room for a bearing between each pair of cranks1 so that a four-cylinder engine will have five bearings1 one at each end1 the other three being between the cranks4 ,if the cylinders are in pairs1 there will not be room between the cranks of a pair for a bearing1 the only space for it being between the pairs2 a four-cylinder engine built in this way will thus have but three bearings1 one at each end and one in the center4 ,crank shafts are described by their bearings as three1 five1 etc41 point crank shafts4 ,illustration3 ,,fig4 #c4--;,,gasoline ,,engine ,,in ,,section4 ,illustration3 ,,fig4 #d4--;,a1 ,two-throw crank shaft2 ,b1 four-throw crank shaft1 #ahj4 ,the relative positions of the cranks of a crank shaft are expressed in degrees of a circle2 if1 for instance1 the cranks project from opposite sides of the shaft so that they are a half revolution apart1 it is called a #ahj-;degree crank shaft4 ,the outer ends of the crank arms1 which correspond to the cranks of a bicycle1 support the crank pin1 which may be likened to the pedal1 and to this the large end of the connecting rod is attached1 the small end being connected to the piston4 ,the connecting rod must be of great strength1 tough but not brittle1 and is made of steel or bronze4 ,illustration3 ,,fig4 #e4--,,one-,,throw ,,crank ,,shaft4 ,illustration3 ,,fig4 #f4--;,,connecting ,,rod4 ,the piston is a trifle smaller than the bore of the cylinder1 and its length is usually greater than its diameter4 ,it is hollow1 with one end closed1 the closed end being that against which the pressure is exerted4 ,a wrist pin passes through it1 and through the small end of the connecting rod1 to enable the latter to swing from side to side in following the turning of the crank shaft4 ,a tight joint is maintained between it and the cylinder walls by cast-iron piston rings1 which are of square or rectangular cross-section1 split so that they may spring open1 and fitted into grooves cut around the piston4 ,they are of such shape that their tendency to expand keeps them pressed against the cylinder walls1 but being split1 their elasticity prevents their binding2 they fit the grooves snugly1 and while they may move freely in them1 they hold the pressure from escaping4 ,the number of rings varies with the design of the engine1 but the most usual arrangement is three to a piston1 placed around the upper end4 ,illustration3 ,,fig4 #g4--;,a1 ,piston2 ,b1 piston in section4 ,illustration3 ,,fig4 #h4--,,piston ,,rings4 ,the cylinder should be of the highest grade of cast iron1 with the smoothest possible surface for the piston to slide against4 ,illustration3 ,,fig4 #i4--;,,conical ,,valve ,,seat4 ,illustration3 ,,fig4 #aj4--;,,automatic ,,inlet ,,valve ,,in ,,cage4 ,the valve openings1 or seats1 are circular1 and are usually made slightly funnel shaped1 the disks that cover them being slightly conical to fit4 ,the large end of the funnel is toward the combustion space1 so that when the disk is lifted from its seat it moves inward4 ,valves are held against their seats by coil springs that surround the valve stems1 which are rods extending from the center of the disks1 and there are two methods by which they are opened4 ,in an automatic valve1 the spring that holds the disk against its seat is weak1 and the higher pressure outside of the cylinder during the suction stroke forces the disk away from its seat against the pressure of the spring4 ,the valve remains open until the pressure in the combustion space is about equal to that outside1 when the spring draws the disk back to its seat1 to which it is held as long as the pressure inside is higher than that of the atmosphere4 ,this arrangement is only possible for inlet valves1 and is largely used1 but exhaust valves1 and often inlet valves as well1 are mechanically operated2 that is1 they are opened and held open by a mechanism driven by the crank shaft1 in the form of a cam4 ,a cam can best be described as a 8wheel with a hump on it10 or1 in other words1 it is a piece of metal mounted on a shaft1 cylindrical in form except for one portion1 which projects farther from the shaft than the rest4 ,the cam revolves with the shaft1 and the projection1 called the nose1 will displace anything resting against it4 ,the illustration shows a cam in three positions of its revolution1 with the end of a valve stem resting against it--the roller being attached to the stem to reduce the friction4 ,the valve stem is held in guides1 so that the only movement it may have is up and down2 when the cam revolves1 the nose lifts the stem and opens the valve1 holds it open as long as the flat end of the cam is under the stem1 and when the nose passes from under1 the valve is drawn to its seat by the spring4 ,illustration3 ,,fig4 #aa4--;,,cam ,,action4 ,the moment at which an automatic valve opens is governed partly by the tension of its spring2 if it is too strong1 greater pressure will be required to open it1 and it will close sooner than if the tension is light4 ,accurate adjustment of this spring is necessary in order that the charge may enter the combustion space without delay1 and continue to enter as long as possible4 ,the opening and closing of mechanically operated valves depend on the shape of the cam1 and not being affected by the more or less uncertain action of a spring1 they are more positive in action4 ,the cam shaft on which the cam is mounted is driven by the crank shaft1 but as the valve opens but once during two revolutions1 the cam shaft revolves at half speed1 making one revolution while the crank shaft makes two4 ,this is done by means of gears4 ,if two gears running together1 or in mesh1 have the same number of teeth1 they will make the same number of revolutions1 but if one has twice as many teeth as the other1 the smaller will revolve twice while the larger revolves once4 ,as the cam shaft must revolve but once while the crank shaft revolves twice1 its gear must have twice the number of teeth as the gear on the crank shaft4 ,the cam shaft is also called the secondary1 or half-time shaft1 and the gears that drive it the two-to-one gears4 ,in some designs of engines1 the nose of the cam bears directly against the valve stem1 but it is more usual to place a valve-lifter rod1 or push rod1 between them1 the cam acting on the rod and lifting it1 and that in turn lifting the valve stem4 ,when the nose of the cam is not acting on the stem or rod1 there must be a small space between them1 for if the stem or rod rests firmly against the cam at all times1 the valve disk might be prevented from seating firmly4 ,the space is left between the stem and lifter rod1 the spring acting only on the stem4 ,illustration3 ,,fig4 #ab4--;,,four ,,arrangements ,,of ,,valves4 ,the valves may open into the cylinder in a variety of ways2 both may be in one pocket1 or one may be in a pocket and the other in the head1 or each in a separate pocket1 or both in the head4 ,the first two illustrations show automatic inlet valves1 and the third and fourth mechanically operated valves2 when two mechanically operated valves are in the head1 it is necessary to open them by means of rocker arms1 for because of their position it would be impossible for the valve-lifter rod to act directly on their stems4 ,if after the explosion the burned gases were permitted to escape directly into the open air from the cylinder1 the effect would be the same as the firing of a gun1 and for the same reasons4 ,the pressure in the cylinder being higher than that of the atmosphere1 the sudden expansion of the gases would produce a report1 and as this would be most undesirable for an automobile1 provision is made by which the gases are cooled and permitted to expand gradually1 so that when they reach the open air they are at its pressure1 or nearly so4 ,this is done in the muffler1 or silencer1 to which the exhaust pipe conducts the products of combustion4 ,the muffler consists of a series of chambers of different sizes1 one inside of the other2 the gases pass from the smaller to the larger1 expanding as they go1 until from the largest they should escape without noise1 having lost their heat and pressure4 ,while the pressure exerted during the power stroke depends on the heat of the gases1 and it is necessary to have the engine hot in order that there may be as little loss of heat as possible1 the temperature must not be permitted to rise to the point at which the lubricating oil would burn4 ,lubricating oil for gasoline engines is made to stand high heat1 but if heated beyond its limit it will burn1 and then1 besides the loss of its property of lubrication1 a deposit of carbon1 hard or gummy1 will form1 fouling the combustion space or piston rings1 and interfering with the operation of the engine4 ,overheating is prevented either by circulating water through channels surrounding the combustion space1 or by directing a blast of air against it4 ,illustration3 ,,fig4 #ac4--;,a1 ,force circulation water-cooling system2 ,b1 thermosiphon circulation water-cooling system4 7,flow of water indicated by arrows47 ,the channels1 called water jackets1 provided for the circulation of the water1 are usually cast with the cylinder1 or formed of sheet metal4 ,cool water enters at the bottom and escapes at the top1 absorbing heat during its passage4 ,of the two systems of keeping the water in circulation1 the most usual consists of a rotary pump1 which forces the water through the jackets and then to a cooler1 or radiator1 which is so placed that it is exposed to the air currents set up as the car moves4 ,in order to cool the water1 the radiator must have a large surface exposed to the air1 and the water must pass through it in small streams4 ,the early types consisted of coils of small copper tubing1 on which were strung disks of copper1 the water flowing through the tubing1 and the disks absorbing its heat and giving it up to the air1 but these are being abandoned in favor of cellular or honeycomb radiators4 ,these types1 which are usually placed at the extreme front of the car1 are made up of a great number of short lengths of small tubing1 in any one of several shapes1 placed side by side1 and held together either by plates or by soldering their ends4 ,illustration3 ,,fig4 #ad4--;,a1 ,centrifugal pump2 ,b1 vane pump2 ,c1 gear pump and cover4 ,illustration3 ,,fig4 #ae4--,,radiator ,,constructions4 ,a1 ,spiral flange 7water passes through the tube72 ,b1 cellular1 and ,c1 honeycomb 7air passes through the tubes2 water passes between the tubes74 ,illustration3 ,,fig4 #af4--,,radiator ,,and ,,fan4 ,the heated water enters at the top of the case in which the tubes are contained1 and flows to the bottom1 finding passages between the tubes1 while the air passes through1 being assisted by a fan driven by the engine4 ,the second system of keeping the water in circulation follows the principle that heated water tends to rise1 its place being taken by the cooler water that tends to sink4 ,this1 called the thermosiphon or gravity system1 requires all of the parts and connections to be large and completely filled with water4 ,the water in the jacket rises as it absorbs heat from the cylinder walls1 and flows out to the radiator1 which it enters at the top4 ,its place in the jacket is taken by the cooled water from the bottom of the radiator1 and this circulation continues1 being more rapid as the difference in temperature between the heated and cooled water increases4 ,it is naturally not so rapid as circulation that is forced by a pump1 and more liable to become inoperative by the clogging of the pipes1 jacket1 or radiator4 ,of the methods of increasing the surface of a cylinder in order to cool it by a blast of air1 the most usual is to cast it with flanges that project from all parts of the combustion space4 ,these become heated as the temperature of the cylinder walls increases1 and the air that is blown against them carries off the heat4 ,other methods consist of setting pins or copper strips into the cylinder walls1 of such form that the air current strikes a surface composed of points1 by which the heat easily passes to the air4 ,another system consists of surrounding the combustion chamber with a jacket open at the bottom1 air being blown into it from the top by a powerful blower4 ,other things that are necessary for successful air cooling are large valves by which the hot gases may be quickly discharged when their period of usefulness is ended1 and small cylinders rather than large1 as the heat from small quantities of gases may be carried off more quickly than from large4 ,the lubrication of a gasoline engine must be carefully looked after1 as on its thoroughness depends the continued delivery of power4 ,the most usual method of lubricating the piston and cylinder walls is to keep the crank case filled with oil to such a point that the end of the connecting rod dips into it in turning4 ,this spatters the oil to all parts of the crank case1 and a portion is caught in a groove cut around the lower end of the piston4 ,the inward movement of the piston spreads the oil on the cylinder walls1 and it is distributed around the piston rings1 so that they move easily in their grooves4 ,as the oil is used up1 it is replaced from a lubricator so that a constant level is maintained1 and this operates either by gravity1 or by a small force pump driven by the engine1 or by the maintaining of pressure in the oil tank4 ,mechanically operated or pressure lubricators supply oil to all parts of the engine1 and as the quantity passed to each bearing is adjustable1 a feed may be maintained that is exactly suited to the requirements4 ,the bearings of an automobile operate under such widely different conditions that one kind of lubricant will not be suitable for all4 ,the maker of the car has tested the different oils1 and it is advisable to follow his instructions on the brand and grade most suitable for each bearing1 rather than to try experiments4 ,the ,lubrication ,table on pages #bdd and #bde gives the kind and quantity of lubricant most suitable to the work performed by each bearing4 ,,chapter ,,iii ,,engine ,,balance ,a drawback to the use of reciprocating engines is that the weight of the piston and connecting rod in sliding first one way and then the other produces great vibration1 and that the crank shaft in bringing these parts to a stop at each end of the stroke is subjected to violent shocks that in time wear it loose in its bearings4 ,with internal-combustion engines this vibration1 and the shock on the crank shaft1 are greatly increased by the intensity with which the pressure is exerted4 ,engines with one cylinder may be balanced to some extent by the use of counterweights attached to the crank shaft1 and by the use of so heavy a fly wheel that its momentum produces a comparatively steady movement2 but a perfect absorption of the vibration would require the engine to be run at a constant speed1 which is not possible with those used on automobiles4 ,in two-cylinder engines the vibration may be reduced by so arranging the parts that the pistons slide in opposite directions1 the weight of one being balanced by that of the other4 ,this plan is used in engines of the horizontal double-opposed type1 which is considered to be the most satisfactory for low powers4 ,the cylinders are horizontal1 with their open ends toward each other1 the crank shaft lying between them4 ,the crank shaft is two-throw1 #ahj2 that is1 there are two pairs of crank arms1 projecting from opposite sides of the shaft1 so that they are a half revolution apart4 ,two cylinder engines are also built with vertical cylinders1 and are of two types1 according to the construction of the crank shaft4 ,in one1 the crank shaft is #ahj1 and in the other both pairs of crank arms project from the same side of the shaft so that the crank pins are in line1 this being called a #cfj crank shaft4 ,in the #ahj type one piston moves up as the other moves down1 so that they balance1 but it results in the power strokes occurring in both cylinders during one revolution of the crank shaft1 with no power during the revolution that follows4 ,to understand the reason for this1 the order in which the events of the cycle occur must be recalled1 and it must be remembered that of the four strokes of the piston during which they are performed the two outward strokes are inlet and power1 and the two inward strokes compression and exhaust4 ,if the piston of a two-cylinder vertical engine 7,fig4 #ag7 is moving downward on the power stroke1 piston ,no4 #b will be ascending1 and the only events that can then be performed in its cylinder are compression or exhaust4 ,if performing compression1 it will move under power during the next stroke 7the other half of the revolution71 ,no4 #a then exhausting 7,table ,no4 #a74 ,this brings the two power strokes in one revolution1 and during the next revolution there will be no power stroke1 for ,no4 #a will be performing suction and compression1 and ,no4 #b exhaust and suction4 ,illustration3 ,,fig4 #ag4--;,,engine ,,arrangements ,,showing ,,order ,,of ,,firing4 ,if1 as shown in the second table1 ,no4 #b is moving upward on exhaust while ,no4 #a moves down under power1 its previous stroke1 the first half of the revolution1 will have been the power stroke1 and the same condition will exist of two power strokes occurring in the same revolution4 ,in either case the balance of the moving parts is offset by the irregular production of power1 which produces bad results in the setting up of strains in the engine1 and the uneven running of the car4 ,in two-cylinder vertical engines with #cfj crank shaft 7,fig4 #ag7 the pistons move up and down together1 which of course results in bad balance4 ,in this arrangement1 however1 the applications of power may be evenly spaced1 for as the piston in cylinder ,no4 #a moves downward on the power stroke1 piston ,no4 #b moves in the same direction1 and may make either the inlet or power stroke4 ,if it makes the inlet stroke1 it must move inward before it can again move outward on the power stroke1 and there will be an interval of one stroke between the power strokes of the two cylinders4 ,to have the power strokes in the two cylinders occur together1 as suggested as the alternative1 would obviously give bad results in the great strain imposed on the crank shaft1 the weight of the fly wheel that would be necessary to carry two pistons through three dead strokes1 and the jerky running of the car4 ,the defects of two-cylinder vertical engines with either design of crank shaft outweigh any possible advantage of that construction1 and the horizontal double-opposed type1 in evenly occurring power strokes1 mechanical balance1 and simplicity1 is in almost universal use for cars of low power4 ,a two-cylinder engine does not require so heavy a fly wheel as a one-cylinder engine in proportion to the power delivered1 because there is a power stroke every revolution instead of in alternate revolutions1 and the parts must be carried over only one dead stroke instead of three4 ,similarly1 the fly wheel of a four-cylinder engine may be still lighter1 for in that type there are two power strokes in every revolution1 with no dead strokes4 ,at the same time1 it is not possible to dispense with it entirely1 for the pressure acting on the piston at the beginning of the power stroke falls rapidly as the piston moves before it1 and the momentum by which the fly wheel tends to revolve at a constant speed steadies and smooths what would otherwise be a jerky motion4 ,the crank shaft of a four-cylinder engine is #ahj1 four-throw1 with the two end cranks projecting in the opposite direction to that of the two inside cranks4 ,this arrangement is used in preference to having the cranks project alternately2 that is1 the first and third to one side and the second and fourth to the other1 because of economy in manufacturing1 and because practice has shown that it results in less vibration in the running of the engine4 ,this construction of the crank shaft does not permit the power strokes to occur in rotation1 cylinder ,no4 #b following ,no #a1 and then ,nos4 #c and #d1 for it has been explained that when cranks are #ahj apart the power strokes occur during one revolution1 and that when #cfj apart there is a dead stroke between the two power strokes4 ,cranks #a and #b are #ahj apart1 as are #c and #d1 and also #b and #d1 but #b and #c are #cfj2 that is1 their crank pins are in line1 which is also the case with #a and #d4 ,the power stroke in cylinder ,no4 #b may follow that in cylinder ,no4 #a1 but must be followed by that in cylinder ,no4 #d1 as that is #ahj away from ,no4 #b1 and ,no4 #c comes last1 being #ahj from ,no4 #d4 ,the succession in which the power strokes occur1 called the firing order1 is thus #a1 #b1 #d1 #c1 and this is arranged for by the setting of the valves and the timing of the ignition4 ,this firing order was used for the first four-cylinder automobile engines1 but it has lately been suggested that the firing order #a1 #c1 #d1 #b shows advantages in the reduction of strains and vibration1 and is being adopted4 ,three-cylinder engines are built with #abj crank shafts2 that is1 the cranks are one third of a revolution apart1 instead of one half of a revolution1 as is the case with #ahj crank shafts4 ,this gives three power strokes during two revolutions1 and results in excellent balance4 ,six-cylinder engines have crank shafts of similar construction1 and produce six power strokes during two revolutions1 with the best balance that it is possible to obtain without an excessive number of cylinders4 ,a power stroke occurs at every #abj that the crank shaft revolves1 and as each power stroke endures for a half revolution1 or #ahj1 it follows that one commences when the previous one is only two thirds complete4 ,this gives a very steady application of power1 for the crank shaft is at all times operated by the driving effect of the combustion strokes1 and it is possible to run the engine smoothly at greatly varying speeds by control of the position at which the spark occurs in the combustion space1 and the admission of a greater or less volume of the mixture during the inlet stroke4 ,the type of engine that will give satisfaction depends on the work that is demanded of it1 the care that it will receive1 and the knowledge of the operator4 ,a one-cylinder engine1 having a minimum of parts1 may be successfully managed by a novice1 but its vibration1 and the fact that it delivers power for only one fourth of the time that it runs1 make it unsatisfactory for any but light work4 ,cars of medium power are almost universally equipped with horizontal double-opposed engines1 with excellent results1 and they are not difficult to maintain4 ,more powerful cars have four-cylinder vertical engines1 which give a sufficiently constant pull for all practical purposes1 with a correspondingly greater demand for care and attention4 ,six-cylinder engines are of doubtful advantage for general use1 without the services of a chauffeur1 for while they develop more constant power than engines with fewer cylinders1 the complication of parts and the care necessary are increased4 ,,chapter ,,iv ,,two-,,cycle ,,engine ,the two-cycle type of gasoline engine differs from the four-cycle type described in the foregoing chapters in that the five events composing the cycle are performed during one revolution of the crank shaft1 or two strokes of the piston1 power being developed during every outward stroke of the piston instead of alternate outward strokes4 ,illustration3 ,,fig4 #ah4--,,two-,,cycle ,,engine4 ,in order that this result may be attained1 the construction of the engine is changed1 and1 as will be seen in ,fig4 #ah1 the crank case is utilized as a receiver for the mixture before it passes to the combustion space4 ,the valves are replaced by ports1 which are openings into the combustion space that are covered and uncovered by the piston as it slides in the cylinder4 ,the inlet port is uncovered when the piston is at the inmost point of its stroke 7,fig4 #ah1 ,a71 and then admits the mixture to the crank case2 the by-pass port and the exhaust port are uncovered when the piston is at the outmost point of its stroke 7,fig4 #ah1 ,b71 the former then permitting the mixture to pass from the crank case to the combustion space1 and the latter is that through which the burned gases escape after combustion has taken place4 ,during an inward stroke1 the pressure in the crank case is reduced as the piston slides away from it1 and fresh mixture is forced into it by the higher atmospheric pressure as soon as the inlet port is uncovered4 ,this port is covered when the piston makes an outward stroke1 and the mixture1 not being able to escape1 is compressed4 ,its tendency to expand causes it to flow to the combustion space when the by-pass port is uncovered1 and in entering it strikes a ledge on the piston so that it is deflected to the top of the combustion space instead of being able to shoot across the cylinder and out the open exhaust port4 ,the inward stroke of the piston covers these two ports and compresses the mixture1 ignition occurring in the regular manner4 ,the pressure developed by the combustion drives the piston outward1 and as soon as the exhaust port is uncovered 7which is slightly before the uncovering of the by-pass port71 the gases1 which are still expanding1 begin to escape1 and are further expelled by the fresh charge that enters and drives them before it4 ,thus the five events of the cycle are performed during an inward and an outward stroke of the piston1 the crank case end of the piston drawing a charge of fresh mixture into the crank case and forcing it into the combustion space1 and the combustion chamber end compressing it and being acted on by the pressure from the combustion4 ,at slow speeds1 two-cycle engines have advantages over the four-cycle type in the production of a power stroke at every revolution of the crank shaft1 and the absence of valves and valve mechanism with their weight and possibility of giving trouble4 ,this simplicity makes the two-cycle engine popular for motor boats1 where they are run at slow and constant speed1 but for higher and changing speeds these advantages are outweighed by disadvantages that show little sign of being overcome4 ,with the engine running at a thousand revolutions a minute1 it can be understood that the ports will be open for only a brief period during each stroke1 and that the faster the engine runs the shorter will be the period during which the gases may enter or leave the combustion space4 ,the inefficiency of two-cycle engines as compared with engines of the four-cycle type is due entirely to the fact that the burned gases have not sufficient time in which to escape from the combustion space1 nor the fresh charge time to enter4 ,the fresh charge that does enter being incomplete1 and being contaminated by the portion of the burned gases that has not been able to escape1 result in the 8choking up0 of the engine1 and in the production of lower power than the dimensions and weight of the engine should warrant4 ,,chapter ,v ,,carburetion ,,and ,,gasoline ,,feeds ,pure gasoline vapor will not burn1 and in order to render it inflammable it must be combined with oxygen4 ,the simplest manner of effecting this is to mix air with it1 and when the correct proportions are obtained1 the oxygen supplied by the air will be sufficient to result in the complete combustion of the gasoline vapor1 without a surplus of either of the ingredients4 ,this mixing is called carburetion1 the air being said to be carbureted4 ,a correct proportion of gasoline vapor and air results in rapid combustion2 an excess of air makes combustion slower1 and excess of gasoline vapor prevents the combustion from being complete1 a residue of carbon remaining4 ,the correct proportions of air and gasoline vapor are obtained by the use of a device called a carburetor1 which is connected to the combustion chamber by the inlet pipe1 and in such a manner that everything entering the combustion space by the inlet valve must first pass through it4 ,liquid gasoline is led to the carburetor from the supply tank1 and the air enters it when the pressure in the combustion space is reduced by the piston in making the inlet stroke4 ,the speed with which the air flows through the carburetor depends on the extent to which the pressure is reduced1 and the gasoline vapor that is required to form a mixture of the correct proportion must be maintained in accordance with it4 ,while there are various classes of carburetors1 practically all that are used for automobile engines are of the float-feed type2 that is1 the supply of gasoline is maintained by a float1 just as water tanks are kept filled to a desired depth by a hollow metal ball that floats on the liquid and controls the valve by which the water enters4 ,illustration3 ,,fig4 #ai4--;,,carburetor ,,principles4 ,the principal parts of a float-feed carburetor are the float chamber and the mixing chamber1 the gasoline flowing from the supply tank to the float chamber1 and from there to the mixing chamber1 where it is combined with the air4 ,the gasoline flows out of the float chamber through a small pipe1 the end of which1 called the spray nozzle1 projects into the mixing chamber so that the current of air rushes past its tip 7,fig4 #ai74 ,when the inlet stroke is not being performed1 and there is no air passing through the mixing chamber1 the float in the float chamber keeps the gasoline at such a level that it stands just below the tip of the spray nozzle4 ,in this condition the gasoline in both the float chamber and the spray nozzle is under atmospheric pressure2 but when the pressure in the combustion space is reduced as the piston makes the inlet stroke1 the pressure in the inlet pipe and mixing chamber is also reduced1 and the gasoline will be forced out of the spray nozzle by the higher pressure in the float chamber4 ,the passage in the tip of the spray nozzle is small1 and the gasoline is broken up into fine drops as it spurts out1 and in this condition is partly absorbed by the air and partly carried into the cylinder4 ,by regulating the amount of gasoline that may pass out of the spray nozzle1 it may be adjusted to the volume of air flowing through the mixing chamber1 so that any desired proportion may be obtained4 ,if the engine were to be run at a constant speed1 the relative pressures on the gasoline in the float chamber and spray nozzle1 and the quantity of gasoline forced out of the spray nozzle1 would remain in correct proportion to the volume of air2 but as the engine of an automobile is run at greatly varying speeds1 the pressure in the mixing chamber is not constant1 but varies to correspond4 ,if the piston makes fifty inlet strokes a minute1 the reduction of the pressure in the mixing chamber is more gradual than would be the case with the piston making two hundred inlet strokes a minute4 ,the more rapidly the pressure is reduced1 the greater will be the effect of the unchanging atmospheric pressure in the float chamber1 and the more gasoline will be forced out of the spray nozzle4 ,this will result in the presence of too much gasoline in proportion to the air1 giving a mixture that is too rich4 ,it is therefore necessary to provide an arrangement by which the pressure in the mixing chamber will not be changed as the speed of the engine varies1 and this is accomplished by the auxiliary air inlet1 which is closed when the engine runs slowly1 but opens to correspond with increasing speed 7,fig4 #ai74 ,the faster the engine runs1 the more the auxiliary air inlet will open1 to admit a correspondingly greater amount of air to prevent the pressure in the mixing chamber from being reduced below the point at which the required amount of gasoline is forced out of the spray nozzle4 ,the most rapid combination of the gasoline and air is secured by breaking the gasoline up into fine spray as it leaves the nozzle4 ,in order to break the gasoline into fine particles1 the tip of the spray nozzle is made with a fine opening1 and often forms the seat for the gasoline adjusting valve1 which is a needle-pointed rod that is screwed in or out to reduce or enlarge the opening2 a further breaking up results from the placing of a metal cone1 or the end of a rod1 in such a position as to be struck by the gasoline as it flows out4 ,a carburetor with an auxiliary air inlet is provided with two points of adjustment1 to control the flow of gasoline from the float chamber to the spray nozzle1 and to govern the admission of the auxiliary air4 ,the flow of gasoline must be just sufficient to carburet thoroughly the air passing through the mixing chamber when the engine runs at low speed1 and the auxiliary air inlet must open to correspond with increasing speed1 to admit sufficient air to keep the pressure reduced to proper proportions4 ,the auxiliary air inlet may be operated either by the reduced pressure that permits the atmospheric pressure to open a valve1 or by the governor of the engine1 which opens the inlet as the speed increases1 and closes it on slowing down4 ,the first of these two types1 called an automatic carburetor1 is in most general use for automobiles1 and is sufficiently satisfactory1 but is not as accurate as the mechanically controlled type1 which acts independently of pressure1 and exactly according to the speed of the engine4 ,illustration3 ,,fig4 #bj4--;,,automatic ,,carburetors4 ,carburetors may be divided into two types1 according to design3 those in which the float and mixing chambers are side by side1 and those in which the mixing chamber passes through the center of the float chamber 7,fig4 #bj74 ,the former is along the lines of the first forms of float-feed carburetors1 and the latter is of more recent design1 its object being a more compact device1 and one that is not affected by a change of level when the car is on a hill4 ,both have advantages and disadvantages1 and the use of one as against the other is optional and a matter of opinion4 ,the carburetors illustrated are not of any particular makes1 and are intended to show principles rather than construction4 ,in carburetors with a side mixing chamber the float is usually a metal box1 the joints of which are as far as possible proof against leakage4 ,guides prevent it from having any but an up-and-down motion1 and in thus moving it controls the gasoline inlet valve by a rod attached to it1 or by a separate valve stem4 ,in this carburetor a separate valve stem is used1 and it is moved through the action of a rocker arm controlled by the float4 ,this construction is usual when the gasoline enters the float chamber from the bottom1 the flow being permitted or checked by a needle valve4 ,when the level in the float chamber drops as the gasoline runs out of the spray nozzle1 the float sinks1 and lifts the valve point from its seat4 ,this admits gasoline from the supply tank1 and the float in rising on it depresses the valve point1 shutting off the flow4 ,the gasoline adjusting valve is in the passage between the float and mixing chambers4 ,the main or initial air inlet is in the side1 the air being drawn through the mixing chamber1 and past the spray nozzle4 ,the auxiliary air inlet is a simple valve1 opening inward1 and held against its seat by a coil spring1 the tension of which is adjustable4 ,the pressure in the mixing chamber being reduced in accordance with the increasing speed of the engine1 the valve is opened more and more as the atmospheric pressure against the outer surface of the valve overcomes the tension of the spring4 ,in carburetors with central mixing chamber the float is ring- or horseshoe-shaped1 and usually made of cork1 well varnished to prevent the absorption of the gasoline4 ,the air enters at the bottom1 passing directly to the mixing chamber4 ,the auxiliary air inlet is at the top1 and is of the arrangement already described4 ,the mixture passes out at the side1 and may be controlled by a throttle1 which may be a damper arrangement1 as shown1 or other device by which the quantity passing to the combustion space is at the will of the operator4 ,the float and mixing chambers of a mechanically operated carburetor are the same as in the side-float chamber type1 the difference being in the control of the auxiliary air inlet 7,fig4 #ba74 ,this consists of a tube attached to the mixture outlet1 within it sliding another tube moved by the governor as that expands or contracts with the speed of the engine4 ,there are openings in the sides of both tubes1 but when the sliding tube is at its inmost position these are not in line1 and consequently are closed4 ,when the governor acts with increased engine speed1 the sliding tube is drawn out1 and one or more openings come into line1 air entering through them to the mixing chamber4 ,the faster the engine runs1 the larger become the openings1 and in consequence the greater is the amount of air that they admit4 ,the illustration shows the ball type of gasoline valve1 the ball on the end of the valve stem being drawn against its seat as the float rises4 ,illustration3 ,,fig4 #ba4--,,mechanically ,,controlled ,,carburetor4 ,while these types are in practically universal use for automobile engines1 there are other methods by which the proportions of the mixture may be maintained4 ,in one form the gasoline drops on a funnel made of fine wire gauze1 which is placed in the mixing chamber in such a manner that the air in entering passes through it4 ,the liquid forms a film over the gauze1 and is picked up by the air1 as it is in a condition that permits it to evaporate rapidly4 ,in surface carburetors air is forced through the gasoline tank1 or through an absorbent material soaked with gasoline1 and becomes thoroughly saturated4 ,this mixture is then thinned with pure air until the desired proportion is obtained1 when it passes to the combustion space4 ,the objections to these forms arise from the clogging of the parts with the impurities present in gasoline1 and while they give excellent results when new1 they deteriorate rapidly and present such resistance to the flow of the air current that they become useless4 ,illustration3 ,fig4 #bb4--;,,float ,,feed ,,carburetor ,,with ,,gravity ,,gasoline ,,feed4 #a1 ,filling cap2 #b1 tank2 #c1 gasoline valve2 #e1 trap and strainer2 #f1 carburetor2 #g1 float chamber2 #h1 float2 #i1 float valve2 #aj1 spray nozzle2 #aa1 gasoline adjustment2 #ab1 air adjustment2 #ac1 throttle2 #ad1 mixing chamber2 #ae1 initial air inlet2 #af1 primer4 ,there are two methods of supplying the carburetor with gasoline4 ,of these the most usual is the gravity feed1 in which the tank is placed at a higher level than the carburetor1 so that the gasoline flows down to it4 ,the tank is usually placed under the seat1 and the piping so arranged that the carburetor is the lowest point of the system4 ,this method of feeding is satisfactory if the tank can be placed sufficiently above the carburetor to have the flow unaffected by an ordinary hill1 but if it is not so placed1 a steep ascent may tilt the car to such an extent that the carburetor is above the level of the gasoline in the tank1 in which case the flow of course ceases4 ,the pressure feed1 which has been adopted on all high-grade cars1 operates through the maintenance of pressure in the supply tank1 the gasoline being forced out without regard to gravity4 ,the tank is tight1 so that the pressure cannot escape1 and is connected by a long pipe of small diameter either with the combustion space of one of the cylinders or with the exhaust pipe1 so that the pressure of the burned gases is maintained in it4 ,as the pressure cannot exist until the engine is running1 a hand air pump is usually provided1 by which a sufficient pressure may be produced in the tank to force out enough gasoline for starting4 ,it is necessary to use as long a pressure pipe as possible1 in order to prevent the possibility of flame passing through it to the supply of fuel1 a long pipe1 exposed to the air1 cooling the gases to such an extent that they cannot ignite the gasoline4 ,illustration3 ,,fig4 #bc4--,,pressure ,,feed ,,gasoline ,,system4 #a1 ,filling cap2 #b1 tank2 #c1 pressure pipe2 #d and #e1 check and relief valves2 #f1 hand pump2 #g1 check valve2 #h1 pressure gauge2 #i1 feed pipe2 #aj1 carburetor4 ,the pressure pipe is always fitted with a check and relief valve1 which acts as a safety valve in preventing the pressure in the tank from reaching a point at which the joints might be strained1 and also retains the pressure which would otherwise escape when the engine stops4 ,in some cars an auxiliary gasoline tank is provided on the dash1 being fed by pressure from the main tank1 and from which gasoline flows to the carburetor by gravity4 ,the short distance of this tank from the carburetor and its elevation prevent the possibility of the flow being stopped by any tilting of the car short of an upset4 ,illustration3 ,,fig4 #bc;,a4--,,types ,,of ,,float ,,valves4 ,because of the liability of the presence of water in the gasoline1 as well as dirt and grit1 the gasoline line should be fitted with a strainer1 or trap4 ,this may be in any position1 but it is usual to have it close to the carburetor1 if not built into it4 ,the simplest strainer consists of a number of thicknesses of fine wire gauze1 so arranged that it may be easily taken out for cleaning4 ,this will separate the dirt from the gasoline1 and water may be caught in a trap1 which is a pocket where the water1 being heavier than the gasoline1 may settle and be drawn off4 ,,carburetor ,,parts ,practically all the carburetors on the market are combinations of a few forms of float valves1 auxiliary air inlets1 and spray nozzles4 ,in addition to the forms shown in ,figs4 #bj and #ba1 the most usual float valves may be seen in ,fig4 #bc;,a4 ,in the first two types shown in this diagram1 the float valve stems are separate from the floats1 and are sufficiently heavy to shut off the flow of gasoline by their weight4 ,in the third type1 the gasoline enters the float chamber from the top1 and as the valve stem is attached to the float1 the rising of the float results in the shutting off of the gasoline4 ,the fourth type is in use on carburetors with central mixing chambers1 the float being hinged to one wall of the float chamber4 ,the loose valve stem is supported by the hinge1 and rises to a seat in the valve when the gasoline is at the proper depth on the float chamber4 ,illustration3 ,,fig4 #bc;,b4--,,types ,,of ,,auxiliary ,,air ,,inlets4 ,fig4 #bc;,b illustrates the most usual forms of auxiliary air inlets4 ,in the first type1 the valve disk slides on the valve stem1 and enlarges the size of the main air inlet4 ,all of the air thus passes the spray nozzle4 ,in the second type1 the inlet for the auxiliary air is separate from the main air inlet1 the two currents meeting in the mixing chamber1 and the extra air diluting the rich mixture that is formed at the spray nozzle4 ,this action is more correct in theory than that of the preceding type1 and better practical results are obtained from it4 ,these air valves are defective in opening and closing too abruptly1 and in tending to vibrate rather than to remain open a fixed distance4 ,the air inlet illustrated in the fourth diagram was designed to overcome these faults4 ,when the engine is not operating1 the air inlets are closed by a hollow piston that is held up by a spring4 ,the upper part of the piston rod carries a metal disk that is attached by a flexible leather washer to the walls of an upper chamber4 ,the portion of the chamber above the disk is tightly closed1 except for a small hole in the cover that provides the only communication between the atmosphere and the air confined in the chamber4 ,when the engine runs at speed1 the atmospheric pressure against the upper side of the disk is greater than the pressure against the lower side1 and the disk is therefore forced downward against the action of the spring4 ,the movement of the disk moves the piston1 and as this latter slides downward it uncovers the openings and admits air4 ,the small size of the opening in the cover prevents air from entering or leaving the chamber above the disk rapidly1 and the movement of the piston is therefore steady and free from jerks4 ,the third diagram illustrates two positions of a mechanically operated auxiliary air inlet1 controlled by a governor4 ,,chapter ,,vi ,,ignition ,the charge of explosive mixture in the combustion space is ignited1 or set on fire1 by an electric spark1 and the apparatus for producing and controlling this spark is called the ignition system4 ,it is with this part of the mechanism of an automobile that a novice has the greatest difficulty1 for an electric current is usually regarded as being surrounded by an air of mystery4 ,it does its work silently and without visible reason1 and when it fails the average man is under the necessity of beginning at the beginning and examining all of the parts of the system because he has so little understanding of the why of it that he is unable to locate trouble in any but a rule-of-thumb method4 ,the principles of electricity may be involved1 but the production of a current1 its handling1 and the uses to which it may be put are not difficult to understand4 ,speaking broadly1 the parts of the ignition system are the source of current1 the arrangement in the combustion space at which the spark is produced1 the device by which the instant when the spark passes may be controlled1 and the circuit by which these parts are connected4 ,before going into a description of these1 however1 it is necessary to understand something of the nature and action of an electric current4 ,every generator of electricity has two terminals1 or poles1 and the flow of current from one to the other is due to what may be explained as a difference in pressure between them4 ,this difference in pressure is similar to that existing when two tanks1 one full of water and the other empty1 are connected by a pipe4 ,the water will flow from the full to the empty tank as long as there is a difference in level1 which is the same thing as a difference in pressure1 the flow ceasing when the water in one tank is level with that in the other4 ,when a path is provided between the two poles of the generator1 the current will flow from one to the other1 always in the same direction1 leaving by the positive pole and returning by the negative4 ,because of this tendency to flow1 the current may be made to perform work1 for it will light a lamp1 ring a bell1 or do anything else within its power in order that it may flow from the positive pole of the generator to the negative4 ,in this there is also a similarity to the two tanks1 for if a water wheel is placed in the pipe connecting them1 the flow of water from one to the other will operate it4 ,the path over which the current flows may be formed of any conductor of electricity1 such as carbon or any metal2 substances by which the current will not flow are called nonconductors or insulators1 and those in most common use are rubber1 china and glass1 wood1 wood fiber1 mica1 etc4 ,while all metals are conductors1 some are better than others1 the difference being in the resistance that they offer4 ,a comparison illustrating resistance may be made between the friction presented to the flow of water by a small pipe and by a larger one1 the water flowing more easily through the latter than the former4 ,in flowing1 the current must overcome the resistance of the conductor1 and in so doing will lose part of its strength and will heat the conductor1 there being more loss of current and greater heat as the resistance increases4 ,it is obvious that in order to obtain a current of the greatest strength the conductor by which it flows must present the least possible resistance1 and for this reason copper is used almost universally to convey the current from one place to another4 ,a copper wire will carry safely a current that would heat an iron wire of the same size to the melting point4 ,the resistance of a small conductor is much greater than that of a large one1 so that the size of a conductor must always be considered in relation to the current that is to be conveyed4 ,a current of electricity may be measured1 just as water flowing through a pipe may be measured1 and by the same measurements of pressure and volume4 ,the pressure under which the current flows is measured in volts1 and the quantity that passes in amperes2 there is also a term for resistance1 that being measured in ohms4 ,because of the desire of the current to flow from the positive to the negative pole1 the circuit must be so guarded that there may be no leakage1 for if it can return to the generator without doing its work it will do so1 taking any path that offers less resistance to its passage4 ,leakage is prevented by insulating the wires1 which may be done by wrapping them with silk or cotton thread1 or by coating them with rubber4 ,the wire by which the current flows from the generator to its work is called the lead 7pronounced leed71 and the conductor by which it flows back1 the return4 ,the greatest care must be taken that there is no leakage from the lead wire in order that there may be enough current to perform the work2 but when the current has done what was expected of it1 any conductor that does not present too much resistance will serve to return it to its source4 ,while wire is sometimes used on ignition circuits for the return as well as the lead1 the most usual method is to utilize the metal of the engine to return the current to its source4 ,the engine being made of iron1 it is a conductor1 and while this metal is not so good a conductor as copper1 yet there is so much of it in an engine that its resistance need not be considered4 ,this method is called grounding the return1 the term coming from telegraphy1 in which the dampness of the earth forms one of the conductors4 ,a grounded circuit requires careful insulation of the lead wire1 for as it is very likely to come into contact with the metal of the engine1 a break in the insulation would permit the current to leak and to return to the generator without doing its work1 this condition being called a short circuit4 ,grounding the circuit saves wire and reduces complication2 simplicity is important in automobile work1 and a reduction of the parts much to be desired4 ,in the foregoing the word flow has been used in describing the action of an electric current in a wire1 and there are so many points of similarity with the flow of water in a pipe that the term conveys a better idea than would technical expressions4 ,electricity1 however1 has neither substance nor weight1 and cannot be said to flow or to move in the strict sense of the words2 but as flow is in general use1 and is the most descriptive of the commonly understood words that are applied to it1 it is made use of here4 ,a current of electricity may be generated either chemically or mechanically1 and always at the expense of something else4 ,a chemical generator produces a current at the expense of a metal1 usually zinc1 which is eaten by the chemicals in proportion to the amount of current delivered2 a mechanical generator produces a current at the expense of the power that drives it4 ,chemical generators are of two kinds1 primary and secondary cells4 ,while primary cells are of many forms1 that called the dry cell is universally used for the ignition of automobile engines1 being adapted to the purpose because there is nothing to spill1 and may be used in any position4 ,it consists of a zinc cup lined with some material of the nature of blotting paper1 in which1 but not touching it1 is a stick of carbon1 the space between being filled with absorbent material and broken bits of carbon moistened with the proper chemical solution4 ,the top of the cell is sealed to prevent evaporation1 and thumb nuts on the projecting end of the carbon stick and the zinc cup form the terminals to which the wires are attached4 ,the carbon being the positive pole and the zinc the negative1 the current flows in that direction whenever a circuit is provided4 ,the dry cell gives a current at a pressure of about one and a half volts when new1 the voltage dropping as the cell is used until it is exhausted1 when the trifling cost of a new cell should not be considered in replacing it4 ,a better source of current than the dry cell is the secondary or storage cell1 which is a reservoir rather than a generator4 ,when a current of electricity is passed to it1 usually from a lighting circuit1 a chemical change takes place1 the action being called the charging of the cell4 ,when the change is complete1 the cell is disconnected1 and will then deliver a current because the parts of the cell that underwent a chemical change tend to return to their previous condition4 ,the current that it gives off is practically equal to that by which it was charged1 and may be used steadily or intermittently until the cell is exhausted4 ,it is made of prepared lead plates1 which are placed in a hard-rubber or celluloid jar1 with a cover to prevent the spilling of the solution with which the plates are covered4 ,the charging of storage cells must be done by an expert1 for mishandling will ruin them1 and it is far better to put this matter1 as well as repairs1 in the hands of a man who knows his business than to attempt it without the proper knowledge and appliances4 ,one point that the automobilist must watch1 however1 is the position and quality of the solution in the cells1 called the electrolyte4 ,the cells should always be full enough to have the plates well covered1 and any loss by leakage or splashing should be made up1 for the plates must not be exposed to the air4 ,electrolyte is made by adding one part of chemically pure sulphuric acid to from three to four parts of distilled or rain water1 adding the acid slowly and stirring constantly4 ,the combination of acid and water generates heat1 and care must be taken not to pour the water into the acid1 for the generation of heat would then be so sudden that the mixture would boil and splash1 burning whatever it touched4 ,by means of an instrument called a hydrometer1 the density of the mixture may be ascertained1 and when the proportions are correct the scale should read #a1bjj4 ,hydrometers are made with the instrument inside of a glass tube1 one end of which has a spout1 the other being fitted with a rubber bulb4 ,by inserting the spout in the vent hole of the cell cover1 the tube may be filled with electrolyte1 the hydrometer showing whether or not it is of the correct density4 ,the cells should be tested every little while1 and if the density is not correct acid or water should be added to make it so4 ,never probe inside of the cells with anything but a glass or hard-rubber rod1 for metal would cause a short circuit between the two plates it touched1 and probably ruin the cell4 ,the terminals of a storage cell are marked in order to distinguish them1 the symbols being the plus 77 sign for the positive pole and minus 7-7 for the negative1 these being universally used in this way on all electrical work4 ,in some makes of storage cells the positive pole in addition is painted red and the negative black4 ,a storage cell when fully charged gives a current at a pressure of about two and a half volts2 the voltage drops as the cell is used1 and when it gets down to #a4 #h volts it must be recharged4 ,when a storage cell is discharged1 it should be recharged immediately1 for otherwise it will deteriorate4 ,one dry or storage cell does not give a sufficient current to supply the required spark1 and several must therefore be used4 ,the most usual method of connecting dry cells1 and the only method of connecting storage cells1 to form a battery1 is to connect the negative pole of the first cell to the positive pole of the second1 using a short length of insulated wire of sufficient size1 the negative of the second to the positive of the third1 and so on1 until all of the cells necessary to supply the required current are used4 ,this leaves the positive pole of the first cell and the negative pole of the last cell free to be connected into the circuit4 ,the current obtained will have a pressure that is as much greater than the pressure of one cell as there are cells in the battery2 for instance1 if there are four cells in the battery1 of one and a half volts each1 the voltage of the battery will be six volts4 ,this method is called connecting in series 7,fig4 #bd74 ,illustration3 ,,fig4 #bd4--;,,battery ,,connections4 ,when the voltage of one cell is sufficient1 and it is desired to increase the volume1 or amperage1 of the current1 the cells may be connected in parallel1 which is done by connecting together all of the negative poles by one wire1 and all of the positive poles by another1 the two wires leading to the circuit4 ,this increases the amperage as many times as there are cells4 ,if it is desired to connect the cells so that both the voltage and amperage are increased1 the cells may be divided into two or more groups1 with the same number of cells in each4 ,the cells of each group are connected in series1 and the free poles of the groups connected in parallel1 which is called connecting in series-multiple 7,fig4 #bd74 ,this is a most satisfactory method of connecting the cells for an ignition circuit1 for it gives a uniform current1 and increases the life of the cells4 ,the voltage of the current is equal to the voltage of one cell multiplied by the number of cells in one group1 and the amperage that of one cell multiplied by the number of groups4 ,the action of a mechanical generator1 which when driven produces a current of electricity1 is due to magnetism1 that being understood to be the power sometimes possessed by iron or steel to attract other pieces of iron or steel4 ,magnetism may be manifested either by permanent or electro-magnets4 ,if a piece of steel is magnetized--that is1 made a magnet--it continues to be a magnet1 for steel retains that property1 while iron does not4 ,a magnet made of steel is called a permanent magnet4 ,if a piece of iron is wound with insulated wire through which an electric current passes1 the iron will become a magnet1 and will remain so as long as the current flows4 ,this is called an electro-magnet4 ,the two ends of a magnet are the positive and negative poles1 and the positive pole of one magnet will repel the positive pole and attract the negative pole of another magnet4 ,between the two poles of a magnet there is a constant flow of what are known as magnetic lines of force1 which may be made visible by laying a piece of paper over the two poles and scattering iron filings on it4 ,the filings will form into curves from one pole to the other1 showing the presence of these lines4 ,if a wire is moved across these lines of force1 so that it cuts them1 a current of electricity will be set up in it1 and if the wire is wound into a coil and moved across the lines1 the current will be as much stronger as there are turns of wire cutting them4 ,a mechanical generator consists of a coil of insulated wire1 arranged so that as it revolves in the magnetic field each turn of wire cuts across the lines of magnetic force4 ,the magnet producing the lines of force that compose the magnetic field is called the field1 and the revolving coil of wire the armature4 ,mechanical generators for producing the current for an ignition circuit are of two types1 magnetos and dynamos1 the former being in much more general use than the latter4 ,in a magneto the field is a permanent magnet1 and in a dynamo it is an electro-magnet4 ,the magnets forming the field of a magneto are bent into horseshoe shape1 so that the poles are close together1 and the armature revolves between them4 ,the field of a dynamo is of similar shape1 wound with insulated wire1 the current that flows through it being generated by the dynamo itself2 the field is strongly magnetized only when the dynamo is running4 ,the armature of either type is a piece of soft iron1 with grooves cut in it lengthways1 in which the wire is wound2 the winding thus being contrary to that of thread on a spool4 ,the current generated in the wire of the armature is taken off by means of brushes1 and connection is made through binding posts set in the base4 ,as the care of a mechanical generator requires a knowledge of electrical engineering1 it is better to return it to the makers in case of injury1 rather than to attempt to repair it without the necessary experience4 7,see ,appendix47 ,practically all ignition circuits are provided with two sources of current1 so that in case of the failure of one the other will be available1 and either may be connected into the circuit by means of a switch4 ,the simplest form of switch is a piece of flat spring brass1 pivoted at one end so that the other may be swung from side to side to make contact with one or the other of two brass knobs1 or switch points4 ,one pole of each generator1 usually the negative1 is grounded1 and the other connected to one of the points4 ,the flat spring1 or switch blade1 is connected to the ignition circuit1 so that when it is in contact with one of the points the corresponding source is called on to supply the current4 ,the blade may rest between the points1 not touching either1 in which case the circuit is broken1 and no current flows4 ,,chapter ,,vii ,,ignition--7,continued7 ,while there are various methods by which an electric spark may be produced1 but two are in use for automobile work1 one being the high-tension or jump-spark system1 and the other the low-tension or make-and-break system4 ,the difference between these is in the pressure of the current1 which in the first is great enough to enable it to jump from one terminal to another a short distance away1 forming a spark as it passes4 ,the pressure of the current of the low-tension system is not sufficient to permit it to do this1 but when two terminals of the system are brought into contact so that the current may flow1 a spark will form as they are separated4 ,,make-,,and-,,break ,,system ,in the make-and-break system1 the igniter1 which is the device in the combustion space at which the spark occurs1 is made with two metal points1 one of which is stationary and the other movable1 the latter being acted on by a cam1 through a tappet4 ,as the cam revolves1 the tappet is lifted and the movable point brought into contact with the stationary2 when the nose of the cam passes from under the tappet1 the movable point is snapped away from the stationary through the action of a spring 7,fig4 #be74 ,these points are so connected into the circuit that when they are in contact the current flows1 the circuit being broken when they separate4 ,shortly before the spark is desired the movable point is brought into contact with the other so that the circuit is completed and the current flows1 and they are separated at the instant when the spark is required to ignite the mixture1 this occurring as they separate and break the circuit4 ,illustration3 ,,fig4 #be4--,,make-,,and-,,break ,,ignition4 ,the current that is supplied by the battery is not capable of producing this spark1 for it flows with large volume and small pressure--i4e41 high amperage and low voltage--and it is necessary to transform it to a current of higher voltage and lower amperage1 which is done by means of a primary induction coil4 ,a coil of this description consists of a core made of a bundle of soft iron wires1 around which is the primary winding1 formed by winding several layers of insulated copper wire on it4 ,the core becomes a magnet when a current of electricity flows through the winding1 and ceases to be a magnet when the flow ceases1 the magnetization occurring slowly on the completion of the circuit1 and demagnetization instantly on the breaking of the circuit4 ,the influence of a magnet1 as1 for instance1 its attraction for a piece of iron1 is felt throughout a field the extent of which depends on the strength of the magnetization4 ,when a loop of wire forming a closed circuit is placed in the magnetic field1 a current of electricity will be set up in it whenever the strength of the field changes4 ,if the strength of the field does not change1 no current will be set up2 but the greater the change in strength1 whether from strong to weak or from weak to strong1 the greater will be the strength of the current4 ,this principle is applied in the case of a coil1 for the wire that forms the winding is in the magnetic field of the core1 and a current is set up in it whenever the strength of the field changes4 ,the strongest current will be set up1 or induced1 when the strength of the field changes from no magnetism to a degree when the core is magnetized to its fullest capacity or the reverse1 and when the change occurs in the least possible time4 ,the current that is set up will last only during the time when the change in strength occurs1 ceasing to exist when the strength of the field is uniformly strong or weak4 ,the more rapid the change1 the greater will be the pressure of the current1 but the shorter the period of its existence4 ,it is this induced current that forms the spark in the combustion space1 the battery current serving only to establish the condition that will produce it4 ,when the two points of the igniter come into contact and complete the circuit1 the flow of the battery current through the winding of the coil will gradually magnetize the core1 and on the igniter points being separated1 this flow through the winding will cease1 the strength of the magnetic field dropping instantly from full intensity to practically nothing4 ,this change induces a powerful current in the winding1 which current in passing over the circuit causes a spark between the points of the igniter as they separate4 ,the induced current is set up so instantaneously on the breaking of the battery circuit that the spark is usually considered as being that of the battery current1 but1 as stated1 the battery current serves only to magnetize the core1 the spark resulting from the current induced by its demagnetization on the breaking of the circuit4 ,a magneto is a machine that when driven generates an electric current1 and is in almost universal use for this system of ignition4 ,in many cars the system is so arranged that the driver has his choice between ignition by battery and coil1 as described1 and ignition by magneto1 but the mechanical production of a current is so reliable that many automobile builders rely on the magneto alone4 ,magnetos of the type used for ignition are described in the appendix4 ,,jump-,,spark ,,system ,the jump-spark or high-tension system of ignition depends on the production of a current at such a pressure that it can jump from one point to another through high resistance1 such as is presented by air at ordinary or low temperature1 and especially when compressed1 the spark occurring as it passes4 ,this high pressure is obtained through the use of a secondary induction coil1 which consists of a core and primary winding similar to those of the primary induction coil already described1 and in addition has a secondary winding1 formed by a great length of insulated copper wire1 which to save bulk and weight is very fine1 wound over the primary winding4 ,the change in the strength of the magnetic field produced by the core affects this secondary winding1 just as it affects the primary winding2 that is1 a current is set up in it at every change in the strength of the magnetic field1 the pressure of the current depending on the greater or less extent of the change1 and the rapidity with which it occurs4 ,the magnetization of the core takes place but slowly1 for the particles of iron must absorb it one from the other1 but the demagnetization occurs instantly2 the current that is induced during the demagnetization is therefore the greater1 and is the current that has sufficient pressure to jump across the gap4 ,the ignition system employing this coil consists of two distinct parts3 the primary circuit1 which magnetizes the core1 and the secondary circuit1 which leads to the combustion space the current that is induced in the secondary winding4 ,the primary circuit includes the battery or generator that supplies the current1 the primary winding of the coil1 a timer1 and a vibrator4 ,,the ,,timer ,the spark must occur in the combustion space only at the instant when the mixture is in a condition to be ignited1 and it is obvious that only then is the secondary current required4 ,as the secondary current results from the flow of the primary current through the primary winding1 a device must be included in the primary circuit to permit the current to flow and magnetize the core at this instant4 ,this device is called a timer1 or commutator1 and is nothing more than a revolving switch operated by the engine1 that completes the primary circuit at such times as the secondary current is required1 and breaks the circuit when the secondary current has done its work in the production of the spark4 ,because ignition occurs but once in each cylinder during two revolutions of the crank shaft1 the timer completes the circuit but once in that interval1 and is placed on the half-time shaft that operates the exhaust valves4 ,in its simplest form1 a timer consists of a disk of hard rubber1 wood fiber1 or other insulating material in which is set a metal plate1 mounted on the half-time shaft and revolving with it4 ,a flat spring carried on a plate of hard insulating material bears against the edge of the disk1 and during one revolution of the latter the metal plate set in it will be brought into contact with the spring 7,fig4 #bf1 first diagram74 ,if one wire of the primary circuit is connected to the metal plate of the disk and the other wire to the spring1 it will be seen that the circuit will be complete when the revolution of the disk brings the two together1 and broken when the further revolution of the disk separates them4 ,illustration3 ,,one ,,cylinder ,,two ,,cylinder ,,four ,,cylinder ,,fig4 #bf4--,,types ,,of ,,timers4 ,there is a great variety in the methods by which this result is secured1 the chief essential being that the contact must be made as positively as possible in order that the resistance to the current in passing from one part of the timer to the other may be as low as possible1 and broken equally positively4 ,the number of contacts that the timer makes during one revolution depends on the number of cylinders of the engine1 the revolving part touching two1 three1 four1 or more springs or contact points on the stationary part as it turns4 ,a timer for a two-cylinder engine is shown in the second diagram on ,fig4 #bf1 the third diagram being of a form of timer in which the revolving part is not connected into the circuit1 but serves to bring together a spring and a contact point1 the circuit being completed when they touch4 ,a modern form of timer consists of a ring of hard rubber on the inside face of which are set the metal plates1 while the moving part revolves within it1 and may be a flat spring1 or a plunger1 or a roller1 contact being maintained by a coil spring4 ,the difficulty of attaching a wire to the moving part of the timer is overcome by having its contact in connection with the half-time shaft1 the current flowing from the contact on the stationary part to that on the moving part1 and from there flowing by the half-time shaft to the ground connection of the battery1 for1 as all parts are of metal1 the current can pass from the shaft to the ground connection through the bearings and the engine4 ,if the spark were always required to pass in the combustion space at the same point in the stroke of the piston1 this could be secured by setting the stationary part of the timer in such relation to the moving part that contact would be made when the half-time shaft reached any desired point in its revolution4 ,as it is necessary to change the point at which ignition occurs1 however1 the timer must be so arranged that it closes the circuit earlier or later1 according to conditions4 ,to effect this1 the stationary part of the timer is so made that it may rotate around the shaft for about a half turn1 and it is controlled by a lever on the steering column1 which holds it in any desired position4 ,if the stationary part is rotated in the direction opposite to that in which the half-time shaft revolves1 contact will be made and the circuit closed at an earlier point in its revolution than if it is rotated in the same direction4 ,it must be remembered that the revolution of the half-time shaft1 in operating the exhaust valve1 revolves exactly in accordance with the crank shaft and the movement of the piston1 and that as the moving part of the timer is attached to it1 contact can be made at any desired point in the stroke of the piston by the position in which the stationary part is placed4 ,,the ,,vibrator ,the secondary current occurs whenever the core is magnetized and demagnetized1 and it is clear that the oftener the magnetization occurs the more constant will be its presence4 ,the timer closes and opens the primary circuit1 which results in the production of but two impulses of the secondary current1 and as these are not sufficient to produce the necessary spark1 additional means are employed to make and break the circuit while the timer makes contact4 ,this is accomplished by means of a vibrator1 or trembler1 which consists of a flat steel spring secured at one end1 so that it may vibrate after the manner of a tuning fork4 ,about midway between its ends the point of an adjusting screw touches it1 and when the flat spring1 or blade1 vibrates1 it springs away from this screw and returns to it1 both screw and blade being tipped with platinum to offset corrosion4 ,if one wire of the circuit is attached to the blade and the other to the screw1 the circuit will be complete when the blade touches the screw1 and broken when it springs away from it4 ,in the early type of vibrator the blade was set in vibration by mechanical means4 ,at the end of the blade was a weight1 which rested on the edge of a cam1 the blade then being out of contact with the adjusting screw 7,fig4 #bg74 ,during the revolution of the cam the weight dropped into a deep notch1 thus setting the blade into vibration and the circuit being made and broken4 ,this type has been almost entirely superseded by the magnetic vibrator1 which is more rapid and accurate4 ,in this the blade is so placed that its free end is close to the end of the core of the coil 7,fig4 #bh74 ,when the timer makes contact and the current passes through the primary winding1 the core becomes magnetized and attracts to it the free end of the steel blade1 this movement drawing the blade away from the adjusting screw with which it was in contact4 ,the vibrator is so connected into the primary circuit that the current flows from the battery to the adjusting screw1 thence to the blade and through the primary winding2 when the attraction of the blade by the core draws it away from the adjusting screw1 the circuit is broken1 and the magnetism then ceasing to exist1 the elasticity of the blade causes it to spring back to the screw1 to make contact1 and to be again attracted by the magnetism4 ,illustration3 ,,fig4 #bg4--,,mechanical ,,vibrator4 ,when the weight drops into the notch on the cam1 the flat spring touches the adjusting screw and the current passes4 ,illustration3 ,,fig4 #bh4--,,magnetic ,,vibrator4 ,when the magnetism of the core attracts the vibrator the contact is broken at the adjusting screw4 ,this action continues as long as the timer holds the circuit closed1 and a wave of secondary current is set up in the secondary winding for every make and break that results4 ,by means of the adjusting screw1 the vibrations may be made long and slow1 or short and quick1 with a corresponding difference in the secondary current4 ,as the object to be attained is the production of a spark that will ignite the mixture rapidly1 the vibrator must be adjusted with this end in view2 but it is also advisable to obtain the spark with the least possible expenditure of current1 and with the least wear of the parts4 ,the passing of the battery current through the primary winding establishes the condition that exists in the make-and-break ignition system1 and the demagnetization of the core will set up an induced current that will result in a spark at the points where the circuit is broken2 that is1 at the vibrator and timer contacts4 ,this spark can be greatly overcome in the timer by packing it with vaseline1 which1 being an insulator1 breaks down the spark in flowing between the contacts of the stationary and moving parts as they separate4 ,if the vibrator contacts presented no resistance--an impossible condition--there would be no spark1 but as they will always be slightly burned and corroded1 the spark must be kept as small as the requirements of the secondary current will justify by the adjustment of the screw4 ,in other words1 adjust the vibrator so that it gives the best results in the production of the secondary spark with as little sparking as possible at the vibrator contacts4 ,,the ,,spark ,,plug ,the secondary circuit includes the secondary winding of the coil and the spark plug1 which is the device in the combustion space at which the spark occurs4 ,the spark plug provides two points of metal at a fixed distance apart1 which are so connected into the circuit that the current must jump from one to the other in order to complete its circuit4 ,the secondary current1 as well as the primary1 may make use of the metal of the engine as a ground return1 and one of the points of the spark plug is therefore in contact with the metal1 being supported on a metal sleeve that is screwed into the cylinder4 ,the other point must of course be insulated from it1 for if it were not the current could pass from one to the other without jumping the space between them4 ,the insulation is secured by a tube of porcelain or mica set in the sleeve1 the lower end of a metal rod that passes through it being the required distance from the wire or projection on the sleeve 7,fig4 #bi74 ,this device must be strong enough to resist the pressure in the combustion space during the compression and power strokes1 and must be unaffected by the intense heat4 ,illustration3 ,,fig4 #bi4--;,a1 ,spark plug2 ,b1 spark plug in section4 ,,the ,,circuit ,fig4 #cj shows the primary and secondary circuits of the jump-spark system1 as applied to a one-cylinder engine1 the light lines representing the primary circuit and the heavy lines the secondary4 ,each circuit forms a complete path by which the current passing over it may return to the point at which it started4 ,in practice the wiring is simplified by the use of but one ground return for both circuits1 the primary and secondary windings of the coil being connected at one point1 and the secondary current returning either through the timer as it makes contact or through the battery4 ,illustration3 ,,fig4 #cj4--;,,ignition ,,circuit4 ,wiring diagram for one-cylinder engine1 with coil1 timer1 and two batteries2 coil with magnetic vibrator4 ,the flow of the primary circuit is from the battery to the switch1 to the vibrator1 which is built into the coil1 through the primary winding and the timer contacts1 whence it passes by the metal of the engine and ground wire back to the battery4 ,the secondary circuit consists of a wire from the secondary winding of the coil to the spark plug1 and back to its winding by the metal of the engine and a ground wire1 which1 as has been explained1 may be the separate ground wire shown in the diagram1 or the return that is common to both circuits4 ,the timer makes contact as the half-time shaft revolves1 and the vibrator operates as long as the circuit is closed2 while this occurs1 the secondary current is set up1 and the spark passes4 ,included in the primary circuit and built into the base of the coil is a condenser which1 while of such delicate construction that it is most inadvisable for the automobilist to attempt to examine or repair it1 is of such advantage that it should be understood4 ,a current flowing in a circuit possesses momentum1 and if the circuit is broken1 the momentum will cause the current to flow across the break for a greater or less time1 according to the pressure4 ,this will produce a spark1 and a spark at the vibrator as it breaks the circuit will not only burn away the contacts1 but will prevent the instant demagnetization of the core4 ,the passing of a spark between the vibrator contacts indicates that the current is still flowing through the primary winding1 and that the core is still magnetized4 ,the function of the condenser is to prevent sparking at the vibrator by absorbing the momentum of the current1 and1 what is more important1 to cause the instant demagnetization of the core by the instant breaking of the circuit4 ,while it is usual to provide a multicylinder engine with one coil for each cylinder1 it is possible to equip it with but one1 in such a case a secondary distributer being used4 ,this consists of two parts3 a primary timer1 and a somewhat similar device by which the secondary current induced in the coil is switched from cylinder to cylinder as it is required4 ,for a four-cylinder engine the timer has four contacts1 as in the usual type2 but the primary winding is connected to all of them1 so that as the moving part of the timer revolves1 the core of the single coil is magnetized four times to two revolutions of the crank shaft4 ,a single wire leads the secondary current that is thus induced to the distributer1 by which it is switched to the several cylinders4 ,the moving part of the distributer rotates in unison with the moving part of the timer1 making contact as it does so with contact pieces1 each of which is connected to one of the spark plugs4 ,when the timer makes its contact the distributer is in position to pass the induced current to the proper cylinder1 the connections being made in accordance with the firing order of the engine4 ,while this system has advantages in that there is but one vibrator to adjust1 the fact that the coil is operating for the greater part of the time makes it more liable to injury through heating and the consequent breaking down of its insulation4 ,,chapter ,,viii ,,transmission ,the transmission of an automobile consists of those parts that transmit to the driving wheels the power developed by the engine4 ,,the ,,clutch ,because a gasoline engine must be in operation before it can deliver power1 a clutch is provided by means of which it may run free or be so connected that it drives the car1 one of its two chief parts being attached to the engine and the other to the transmission4 ,when the two parts are in contact1 the transmission is driven1 and when separated1 the engine and transmission are independent of each other1 and may be stationary or in motion4 ,a clutch must be of such a nature that it does not apply the power of the engine instantly1 but gradually1 so that the car starts slowly and without jerking4 ,if the power were to be applied suddenly1 the effort of starting the stationary car would either overcome the momentum of the engine and stop it1 or would jerk the car into such sudden motion that it might be badly wrenched4 ,by making the clutch so that it is permitted to slip when first applied1 the part that is driven is gradually brought to the speed of the part that drives1 when slipping ceases and the two make firm contact4 ,the most usual form of clutch is the friction cone1 in which the fly wheel of the engine is utilized as the driving part1 the rim being broad and thick1 with its inner side funnel-shaped1 or beveled4 ,a metal cone that fits the bevel is carried on the end of a shaft of the transmission1 the shaft at this point being square1 to fit a square hole in the hub of the cone4 ,this arrangement permits the cone to slide along the shaft while always revolving with it4 ,when the cone is pressed to a seat in the fly wheel1 which is accomplished by means of a heavy coil spring1 the friction between its leather-covered surface and the surface of the fly wheel causes the two parts to revolve together1 and by its fit on the square shaft the transmission is set in motion1 and through that the car4 ,the clutch is thrown out of contact by means of a foot pedal that acts on a ring fitting in a groove around the hub of the cone2 when the pedal is released1 the spring forces the cone to its seat 7,fig4 #ca74 ,in order to support it1 the end of the shaft carrying the cone projects into the hub of the fly wheel1 where it rests in a bearing1 this arrangement in no manner preventing the two parts from acting independently of each other4 ,in the reversed type of friction-cone clutch a funnel-shaped ring is bolted to the rim of the fly wheel and forms the seat1 the cone fitting inside of it 7,fig4 #ca74 ,depressing the pedal moves the cone toward the fly wheel instead of away from it1 as in the regular type1 and while there is no difference in the effect of one as against the other1 the reversed type is more compact4 ,illustration3 ,,friction ,,cone ,,clutch ,,reversed ,,friction ,,cone ,,clutch ,,fig4 #ca4--;,,friction ,,cone ,,clutches4 ,the multiple-disk clutch1 which is rapidly coming into use1 depends on the friction between the flat surfaces of metal when pressed together4 ,an experiment illustrating this is to place a silver dollar between two half dollars1 and to press them together between the thumb and finger4 ,it will be found that a light pressure is sufficient to produce friction that will make it difficult to revolve the large coin between the smaller ones4 ,the parts of a simple form of multiple-disk clutch1 as shown in ,fig4 #cb1 are a flange on the engine shaft1 a smaller flange with a square-hole1 square-shaft arrangement on the transmission shaft1 and large and small rings placed alternately4 ,the large rings are driven by the large flange1 fitting loosely on pins1 or studs1 projecting from it1 and the small rings are similarly attached to the transmission shaft4 ,the openings in the large or driving rings are large enough to contain the studs carrying the small rings1 so that when the parts are assembled the outer surfaces of the small or driven rings are in contact with the inner surfaces of the driving rings4 ,a heavy coil spring is arranged to press the small flange toward the flange on the engine shaft1 binding the rings that it carries between the driving rings1 and the latter are often faced with leather to increase the friction between them4 ,when the small flange is released from the pressure of the spring by depressing the pedal1 the driving and driven flanges with their rings are independent of each other1 and the engine may run free while the transmission shaft is stationary or revolving4 ,a clutch of this type is incased and runs in oil1 which prevents the rings from gripping suddenly2 when the pressure of the spring is applied1 the oil is gradually squeezed out from between them1 and the slipping of the driving and driven rings is reduced as they are forced into contact4 ,illustration3 ,,parts ,,of ,,multiple ,,disk ,,clutch ,,multiple ,,disk ,,clutch ,,assembled ,,fig4 #cb4--,,multiple ,,disk ,,clutch4 ,an internal-expanding clutch consists of a broad ring1 or drum1 against the inner surface of which bear two pieces of metal shaped to fit4 ,the pieces of metal1 or shoes1 are pivoted together at one end so that they may be moved in or out1 after the manner of the handles of a pair of scissors2 when open they bear against the inside surface of the drum1 and when closed they are free from it4 ,the drum is attached to the engine shaft and the shoes to the transmission shaft1 the friction between them being so great that the transmission shaft is carried around as the drum revolves4 ,the shoes are kept in contact with the drum by a coil spring1 the depression of a pedal releasing them from its pressure4 ,,change-,,speed ,,mechanism ,the change-speed mechanism1 to which the clutch transmits the power of the engine1 is to the engine what a block and tackle is to a man who lifts a heavy weight1 and is necessary because of the varying resistance to the movement of the car in traversing steep1 rough hills and smooth avenues4 ,a change-speed mechanism may be defined as an arrangement by which the relative number of revolutions of the crank shaft and driving wheels may be altered to suit conditions4 ,if the driving wheels revolve but once while the crank shaft makes twelve revolutions1 the car will move at one sixth the speed that it would have if the wheels revolved once to every two revolutions of the crank shaft1 but it will have six times the ability to overcome the resistance presented by a hill or sandy road4 ,if a gasoline engine were so connected that the relative number of revolutions of the crank shaft and wheels could not be changed1 a slowing down of the car through the resistance presented by a rough hill would slow the engine to correspond1 and as speed is an important factor in the power that the engine delivers1 it would be prevented from doing the work of which it is capable at the time when it was most necessary4 ,by means of the change-speed mechanisms in most general use1 the relative number of revolutions of the crank shaft to one of the wheels may be varied to from two to eighteen1 the former giving the car high speed over a smooth road1 and the latter slow speed1 but greater ability to overcome hills and heavy roads4 ,to attain this result1 gears are used4 ,if two gears having the same number of teeth are in mesh1 they will make the same number of revolutions1 and the force with which the driven gear will revolve will be the same as that of the driving gear1 less the friction of the teeth4 ,if the driven gear has twice the number of teeth of the driving gear1 it will revolve at half the speed1 but with twice the force4 ,the forms of change-speed mechanism most largely used are based on this principle1 which is so applied that the gear driven by the engine may be in mesh with a gear that has many more teeth and revolves much slower in consequence1 or a gear that has possibly one and a half times the number of teeth1 or a gear that has the same number of teeth1 and therefore revolves at the same speed4 ,the sliding-gear mechanism takes its name from the arrangement by which the changes in the combination of gears is effected by sliding them along a shaft1 to mesh with other gears on a shaft driven by the engine4 ,illustration3 ,,neutral ,,slow ,,speed ,,second ,,speed ,,high ,,speed ,,reverse ,,fig4 #cc4--,,sliding ,,gear--,,progressive ,,type4 ,a1 ,sleeve driven by engine2 ,b1 gear on sleeve2 ,c1 gear on countershaft2 ,d1 low-speed gears2 ,e1 second-speed gears2 ,f1 idler for reverse2 ,g1 clutch for high speed2 ,h1 connected to rear wheels2 ,j1 gears sliding on square shaft4 ,the driver changes the gears by moving a lever that in the progressive type moves forward by degrees to move the car on the slow speed1 the intermediate speeds1 and the high4 ,a typical arrangement of the progressive type of sliding change-speed mechanism is shown in ,fig4 #cc4 ,the power of the engine is transmitted to a short1 hollow shaft1 called a sleeve 7,a71 which carries a gear 7,b7 that is in permanent mesh with a gear 7,c7 on the end of the countershaft4 ,parallel to the countershaft is another shaft1 one end of which is held in a bearing in the hollow sleeve2 while the sleeve supports this shaft1 the two may revolve independently of each other4 ,the second shaft is square1 or of such a construction that while the two gears that it carries may slide along1 they revolve with it4 ,the gears on the square shaft are of different sizes1 and in sliding on it come successively into mesh with gears carried on the countershaft4 ,because of the gears between them1 the countershaft revolves when the engine revolves the sleeve2 but the speed of the square shaft depends on the combination of gears in mesh between it and the countershaft4 ,when the sliding gears are in such a position that they are not in mesh with the countershaft gears1 the square shaft is independent of the countershaft1 and may revolve or be stationary1 the gears then being in the neutral position4 ,when the sliding part is moved so that its largest gear is in mesh with the smallest of the countershaft gears 7,d71 the square shaft will revolve at a slower speed than the countershaft1 because its gear is larger than the one driving it4 ,again sliding the moving part will separate these gears1 and bring the next pair 7,e7 into mesh1 the square shaft then moving at a higher speed1 but still slower than the countershaft because of the difference in the size of the gears4 ,sliding the moving part still farther along the shaft will disengage the second-speed gears and engage the high speed1 in which the square shaft revolves at the speed of the sleeve and crank shaft1 this being effected by locking the moving part to the sleeve by means of a clutch 7,g74 ,this clutch consists of several fingers projecting from the moving part1 corresponding to the spaces between similar fingers on the end of the sleeve4 ,the locking together of the square shaft and sleeve gives what is known as the direct drive1 which is of comparatively recent development2 many designs of sliding gears still use a third pair of gears which1 being of the same size1 give the square shaft the speed of the crank shaft4 ,by the use of the direct drive1 the power of the engine is directly applied to the square shaft1 avoiding the loss that occurs through the friction of the teeth of the gears4 ,the revolution of the square shaft is transmitted to the driving wheels1 the speed of the car therefore corresponding to the speed at which the square shaft is driven by the gear combinations between it and the countershaft4 ,to obtain the reverse1 which enables the car to be backed without reversing the engine1 a third gear is introduced between the low-speed gears of the square shaft and countershaft4 ,when two gears are in mesh1 they revolve in opposite directions1 but when one of them is in addition meshed with a third gear1 the first and third will revolve in the same direction1 and opposite to the direction in which the middle gear revolves4 ,when the car is going forward1 the square shaft and countershaft revolve in opposite directions1 but when the reverse gear is introduced between them1 the square shaft is revolved in the same direction as the countershaft1 reversing the rotation of the driving wheels4 ,the ends of the teeth of the gears are chisel-shaped1 instead of being flat1 as in ordinary gears1 so that they will go into mesh easily4 ,the greatest economy in the operation of a gasoline engine results from its running at as nearly constant a speed as possible1 and the gear is therefore changed when the resistance of the road to the movement of the car decreases the speed of the engine1 or permits it to increase4 ,the selective type of sliding change-speed mechanism as shown on ,fig4 #cd is in use on many of the high-grade cars1 and its control differs from that of the progressive type described in that the lever has only a short movement forward and back1 and in addition may slide sideways4 ,to the lower end of the lever is attached a shaft that rocks in its bearings as the lever is moved forward or back1 and slides lengthways when the lever is moved toward or away from the car4 ,illustration3 ,,fig4 #cd4--,,selective ,,type4 ,a1 ,sleeve driven by engine2 ,b1 fixed gear on sleeve2 ,c1 fixed gear on countershaft2 ,d1 low-speed gears2 ,e1 second-speed gears2 ,f1 third-speed gears2 ,g1 clutch for direct drive2 ,h1 rod and arm for third-speed and direct drive2 ,j1 rod and arm for low and second speeds2 ,k1 rod and arm for reverse1 ,l1 rocking-shaft finger in groove2 ,m1 guide plate and control lever2 ,n1 bevel gears on square shaft and jack shaft2 ,o1 idler gear for reverse4 ,the arrangement of the countershaft and square shaft is the same as in the progressive type1 but there are two sets of sliding gears instead of one1 and these are moved by means of arms that extend from rods sliding in bearings at the side of the gear case4 ,when these rods are slid endways1 the gears attached to their arms slide on the square shaft to correspond1 and go in or out of mesh with the countershaft gears4 ,across the ends of these rods are grooves1 which when the gears are in the neutral position are in line with the rocking shaft attached to the control lever4 ,from the inward end of the rocking shaft a finger 7,l7 projects downward into the groove2 when the grooves are in line1 the rocking shaft may be slid endways1 the finger passing from one groove to the next without affecting the rods4 ,when the shaft is rocked1 however1 the finger in engaging one of the grooves slides the rod endways1 shifting the gears controlled by its arm4 ,moving the control lever into such a position that it may enter the middle slots of the guide plate 7,m7 slides the rocking shaft so that its finger projects into the groove of the central sliding rod 7,j71 and if the control lever is then pushed forward so that it enters the front half of the slot1 the sliding rod will be moved by the finger in the opposite direction1 and the low-speed gears 7,d7 will be brought into mesh4 ,bringing the lever back to the central position will separate the gears1 and moving it to the back half of the slot will slide the same gears in the opposite direction1 meshing the second-speed combination 7,e74 ,moving the control lever outward so that it is in line with the outside slot brings the finger into the groove of the sliding rod 7,h7 that moves the third and high speeds 7,f and ,g71 the latter being direct drive1 and the reverse is obtained through the movement of the sliding rod 7,k7 that is engaged by the finger when the control lever is in the inside slot4 ,the movement of this rod brings a third gear 7,o7 into mesh with the low-speed gears on the square shaft and countershaft1 and the rotation of the countershaft is reversed4 ,while this type is in general use1 the gears are often so arranged that the direct drive combination is reached when the control lever is in the third-speed position1 the gears meshed by the fourth-speed position driving the square shaft at a still higher speed4 ,this high speed can only be used for running under the best road conditions4 ,the advantages of the selective type over the progressive are the shorter movements of the control lever and the ability to pass from one speed to any other without the necessity of first meshing and unmeshing those between1 or1 in other words1 there is a neutral position between every combination of gears1 and from neutral any desired combination may be obtained directly without reference to the others4 ,in starting up a car fitted with either of these types of change-speed mechanism1 it is necessary to withdraw the clutch before sliding the gears1 and this is also necessary in changing from one combination to another4 ,the square or corresponding shaft of a change-speed mechanism is always connected with the driving wheels1 and is at rest when the car is standing4 ,with the engine running1 the countershaft will be revolving1 and it will obviously be difficult to slide the stationary gear into mesh with a gear that is revolving4 ,when the clutch is withdrawn1 the countershaft moves only through momentum1 and will be brought to a stop by the contact of the teeth of the sliding gear as that is moved against it1 the two then easily going into mesh4 ,the clutch is then thrown in slowly1 and will bring the speed of the countershaft to the speed of the crank shaft4 ,when the car is moving1 sliding the gears without first withdrawing the clutch will bring together two gears that are revolving at different speeds1 and as it is necessary for them to be rotating equally in order that they may mesh1 either the speed of the car must be changed to bring the speed of the gear on the square shaft to that of the countershaft gear1 or the speed of the engine must be changed to bring the countershaft gear to the speed of the gear on the square shaft4 ,if the change is from a low to a higher speed1 the countershaft will be moving much faster than the square shaft1 and their gears being brought into contact will result in the slowing of one and speeding up of the other until the speeds are the same1 but in so doing the ends of the teeth will grind against each other1 resulting in the wear of the chisel-pointed ends1 if not in the breaking of the teeth4 ,withdrawing the clutch obviates this difficulty1 for it frees the countershaft1 permitting its gear to take the speed of the square-shaft gear without wear or damage1 and when the change is made1 the slow engagement of the clutch brings the speed of both to that required by the crank shaft4 ,,chapter ,,ix ,,transmission--7,continued7 ,while the planetary type of change-speed mechanism1 which is in extensive use for runabouts and light commercial wagons1 also employs gears1 their arrangement is along different lines4 ,the first three diagrams in ,fig4 #ce serve to illustrate the principle4 ,illustration3 ,,reverse ,,slow ,,speed ,,high ,,speed ,,principles ,,of ,,planetary ,,gear ,,transmission ,,section ,,planetary ,,gear ,,transmission ,,fig4 #ce4--,,planetary ,,type4 ,the gear ,a in these diagrams is attached directly to the crank shaft1 and in mesh with it are four other gears 7,b7 of the same size4 ,surrounding them is an internal gear 7,c71 this being a ring with teeth cut on its inner face1 the four gears meshing with it4 ,the shafts1 or studs1 on which the four gears revolve are supported by a metal ring 7,d71 which maintains the gears at equal distances from each other4 ,the first diagram shows the mechanism in the reverse position1 for driving the car backward1 the car being driven by the internal gear4 ,to have the internal gear revolve in the direction opposite to that of the crank shaft1 as is necessary1 the ring supporting the four gears is held stationary1 with the result that as the crank-shaft gear revolves the four gears are revolved on their studs4 ,as these gears are in mesh with the internal gear1 that is revolved1 and moves in the same direction as the four gears and in the opposite direction to the crank shaft4 ,for the low-speed forward1 the ring is released and the internal gear held stationary1 the car now being driven by the ring instead of by the internal gear4 ,if the four gears were free from the internal gear1 they and their ring would revolve with the crank-shaft gear without rotating on their studs1 but being in mesh with the internal gear1 they roll around it as a wheel rolls along the ground1 rotating on their studs4 ,a simple experiment that will illustrate this motion is to crook the forefinger around a napkin ring or similar object1 placing a pencil between it and the finger1 and revolving the ring with the other hand4 ,the finger being stationary1 the pencil1 which is revolved in the opposite direction to the ring1 will roll along it4 ,in this the napkin ring represents the crank-shaft gear1 the pencil one of the four gears1 and the finger the internal gear4 ,as the four gears roll around1 the ring moves also1 for it is carried by the studs on which the four gears revolve4 ,if each of the four gears has fifty teeth1 and the internal gear two hundred teeth1 each gear must make four revolutions in order to roll around the internal gear to the point where it started4 ,the crank-shaft gear also having fifty teeth1 it revolves at the same speed1 and as four revolutions of the four gears are necessary in order that they may roll completely around the internal gear1 the crank-shaft gear will make four revolutions in the same time4 ,the ring moves with the four gears1 and revolves once around the crank shaft in the same time4 ,as the car moves according to the rotation of this ring1 it will go at one quarter the speed that it would make if the wheels were directly connected with the crank shaft instead of with the ring4 ,for the high speed1 the internal gear and the ring are locked to the crank shaft so that all revolve together1 the wheels being driven by either the ring or the internal gear4 ,in these diagrams the drive of the wheels is supposed to be shifted from the internal gear to the ring1 which is not a practical arrangement1 and the planetary change-speed mechanism as applied to an automobile is shown in the lower diagram in ,fig4 #ce4 ,in this there are two sets of crank-shaft gears1 gears and rings1 and internal gears1 one set being for the reverse and the other for low and high speeds4 ,between the two crank-shaft gears is a loose sleeve1 one end of which forms the internal gear for the reverse1 and the other end the ring supporting the studs on which revolve the four gears for the low speed4 ,the sprocket for the chain drive to the rear axle is carried on this sleeve4 ,two more loose sleeves are on the shaft1 one forming the ring on which revolve the four gears for the reverse1 and being extended to form a brake drum outside of the internal gear1 and the other carrying the internal gear for the low-speed combination1 its outside face serving as a brake drum4 ,to obtain the reverse1 a brake band is tightened on the drum of the reverse combination1 which holds stationary the ring supporting the four gears1 giving the result shown on the first diagram of the four gears revolving on their studs1 and rotating the internal gear in the direction opposite to that of the crank shaft4 ,the sleeve bearing the sprocket is thus revolved1 and the car backs4 ,for the low speed1 the reverse brake band is loosened1 and the internal gear of the low-speed combination held stationary by the tightening of the brake band surrounding its drum4 ,the revolution of the crank-shaft gear causes the four gears to revolve on their studs and to roll around the internal gear1 revolving the ring and the sleeve bearing the sprocket1 which now turns in the direction opposite to that resulting to the application of the reverse1 or in the same direction as the crank shaft4 ,for the high speed1 a clutch is engaged that locks the internal gear to the crank shaft1 and the four gears then being held between these two are carried around with them1 and the sprocket rotates accordingly4 ,when this combination is used1 none of the gears are in motion1 all revolving with the crank shaft but not on their studs4 ,the planetary change-speed mechanism gives excellent results for light work1 but having only two speeds forward is not adapted to high-powered cars4 ,as the speeds result from the tightening of brake bands on the drums1 there is no danger of damaging the gears by mishandling1 for the brakes will slip before the teeth will give way4 ,the brakes1 which are leather-lined strips of steel1 require attention from the wearing of the leather1 and the slipping that results from oil working in between them and their drums4 ,no foot clutch is necessary1 for the tightening and loosening of the brake bands is controlled by a lever2 in some designs1 the reverse is applied by means of a foot pedal1 and this may be used in braking the car4 ,illustration3 ,,neutral--,,individual ,,clutch ,,drive--,,low ,,speed ,,high ,,speed ,,low ,,speed ,,reverse ,,single ,,friction ,,drive ,,high ,,speed ,,low ,,speed ,,double ,,friction ,,drive ,,fig4 #cf4--;,,individual ,,clutch ,,and ,,friction ,,drive4 ,the individual-clutch type of change-speed mechanism consists of two shafts1 one being an extension of the crank shaft1 and the other parallel to it 7,fig4 #cf74 ,on the crank shaft is a sleeve bearing the sprocket and a gear1 this sleeve being so arranged that it may revolve loosely1 or be locked to the crank shaft and made to revolve with it by a clutch4 ,the crank shaft in addition bears two fixed gears1 one being for the low speed and the other for the reverse4 ,on the countershaft is a fixed gear in mesh with the gear carried on the sleeve on the crank shaft1 and two loose sleeves bearing gears that are in mesh with the fixed low-speed and reverse gears on the crank shaft4 ,these sleeves are provided with clutches by which they may be locked to the countershaft to revolve with it1 or disconnected from it4 ,when the three clutches are disengaged1 the crank shaft in revolving carries with it the fixed low-speed and reverse gears1 the sleeve bearing the sprocket and gear remaining stationary4 ,the sleeves on the countershaft revolve because their gears are in mesh with the fixed crank-shaft gears1 but the countershaft remains stationary4 ,in engaging the low speed1 the clutch is thrown in1 forcing the countershaft to revolve with the fixed gear1 the fixed gear on the countershaft then revolving the gear and driving sprocket carried on the sleeve on the crank shaft4 ,because of the difference in the size of the gears1 the countershaft will revolve at a slower speed than the crank shaft1 and the driving sprocket will make but one revolution while the crank shaft makes several4 ,this it is free to do1 for the sleeve carrying the sprocket is in no way connected with the crank shaft4 ,for the high speed1 the low-speed clutch is withdrawn1 and the driving-sprocket clutch engaged1 causing the sprocket to revolve with the crank shaft4 ,the reverse is caused by the introduction of an idler gear between the gears of the crank shaft and countershaft1 by which the movement of the latter is reversed4 ,the application of the friction type of change-speed mechanism to automobiles is recent1 and is giving good results for light work4 ,it consists in its simplest form of a heavy disk carried on the engine shaft1 on the face of which runs a wheel sliding on a square shaft1 so that the two may be in contact at any point from the edge to the center of the disk 7,fig4 #cf74 ,when the wheel is at the center of the disk it is not moved1 and the number of speeds at which the square shaft may be driven in relation to that of the disk varies from nothing to the limit1 which is obtained when the wheel is in contact with the outer edge of the disk4 ,for the reverse1 the wheel is moved across the center of the disk1 where it is revolved in the opposite direction4 ,another form of friction drive provides two driving disks1 the wheel bearing against both1 so that its movement is more positive1 and there is less chance for slipping4 ,,final ,,drive ,from the change-speed mechanism the power is passed to the driving wheels by the final drive4 ,illustration3 ,,fig4 #cg4--;,a1 ,propeller or driving-shaft drive2 ,b1 single-chain drive4 ,in the most usual construction the engine is so placed that the crank shaft is at right angles to the axle1 and it is therefore necessary to change the direction in which the power acts1 which is done by means of bevel gears4 ,in ordinary spur gears the teeth are parallel to the shaft1 and the two shafts that carry them are parallel1 while in bevel gears the teeth are at an angle1 and the shafts may be at right angles to each other4 ,in ,fig4 #cg the diagram of the single-chain drive illustrates a car in which the engine is in the center of the frame1 and as the crank shaft is parallel to the axle1 the power may be directly applied4 ,in the illustration of the propeller or driving-shaft drive the crank shaft is at right angles to the axle1 and the power is turned by means of the bevel gears at the rear axle4 ,the single-chain drive can only be used for light cars1 and is usually applied in connection with a change-speed mechanism of the planetary type4 ,illustration3 ,,fig4 #ch4--,,typical ,,universal ,,joint4 ,the propeller-shaft drive requires the use of universal joints1 which are devices that permit one shaft to drive another1 even though they are at an angle with each other4 ,a typical universal joint is illustrated in ,fig4 #ch4 ,the ends of the shafts bear yokes1 the ends of which are pivoted to a block of metal of shape4 ,when the two shafts are in line1 the joint will force one to rotate with the other1 and this will not be prevented if the two are out of line1 for then the pivots will act1 the swinging on its pivots in the yokes4 ,illustration3 ,,fig4 #ch;,a4--,,types ,,of ,,shaft ,,drives4 ,,drive ,,through ,,universal ,,joints 8,,straight ,,line0 ,,drive ,,gear ,,box ,,on ,,rear ,,axle ,the change-speed mechanism is carried on the frame of the car1 and is therefore supported by the springs1 but the axle end of the driving shaft follows the axle as that follows the inequalities of the road4 ,one end of the propeller shaft is therefore comparatively stationary1 while the other is in constant motion1 and if the shaft were inflexible it would be jammed in its bearings and twisted out of line4 ,this is prevented by the universal joints with which the shaft is provided1 there being one and often two in the shaft1 and usually one between the clutch and change-speed mechanism4 ,illustration3 ,,fig4 #ci4--,,live ,,axle--,,non-,,floating ,,type4 ,illustration3 ,,fig4 #dj4--,,live ,,axle--,,full ,,floating ,,type4 ,the single-chain and driving-shaft drives require the use of a live axle1 which is an axle that revolves with the wheels4 ,the simple type of live axle consists of the shaft to which the wheels are attached1 and the housing that contains and supports it 7,fig4 #ci74 ,this axle is continuous1 and usually has square ends that fit into the square hubs of the wheels so there may be no slipping4 ,the second diagram in ,fig4 #dj shows a live axle of the floating type1 in which the revolving part serves only to turn the wheels4 ,the housing is extended1 and the wheels run on its ends1 the driving part projecting beyond the housing and having square ends that are secured to the outside of the hubs by square caps4 ,the wheels thus run on the housing1 which takes the weight of the car from the driving part4 ,a live axle must be divided into two parts in order that a differential gear may be fitted1 and the housing must therefore be strong enough to support the weight and prevent sagging4 ,the efficiency of a bevel gear is greatly reduced if the teeth are not in their exact mesh1 and sagging of the axle will throw them out to such an extent that they will be noisy1 and wear rapidly4 ,the floating type of live axle1 in relieving the driving part of the weight1 has a great advantage over the simple type1 and is in general use4 ,illustration3 ,,fig4 #dj;,a4--,,dead ,,axle ,,with ,,driving ,,shaft4 ,axle supports ,bevel ,gear and ,differential4 ,the ,driving ,shaft is supported in ,bearings at the ,differential end1 and drives the wheels through clutches in the hubs4 ,with the driving-shaft drive it is necessary to use a torsion rod1 which extends from the gear case1 or a crosspiece of the frame1 to the rear axle4 ,the necessity for this is the tendency of the driving bevel gear to roll around on the driven bevel gear rather than to revolve it4 ,if it were not for the torsion rod1 there would be a continual strain on the parts because of the tendency of the axle housing to revolve around the axle1 instead of the axle being revolved inside of the housing4 ,the torsion rod has a flexible joint at one end1 that permits it to give as the axle follows an uneven road surface1 but it retains the housing in the correct position1 preventing the bevel gears from getting out of line 7,fig4 #da74 ,illustration3 ,,fig4 #da4--,,torsion ,,rod4 ,illustration3 ,,fig4 #db4--;,,double ,,side-,,chain ,,drive4 ,in ,fig4 #db is shown a car with double-chain drive1 in which the bevel gears that change the direction in which the power is applied are contained within the gear case that incloses the change-speed mechanism4 ,as will be seen from ,fig4 #cd1 the bevel gears connect the square shaft with the jack shaft1 which is a shaft passing across the car1 and bearing on its ends the sprockets by which the wheels are driven4 ,this type of drive requires the use of a dead axle1 which is stationary with the wheels running loose on its ends1 like the axle and wheels of a coach4 ,an axle of this type may have great strength with light weight1 and is usually a manganese-bronze or steel forging4 ,the sprockets on the rear wheels are bolted to the spokes1 and should be1 of course1 exactly in line with the sprockets on the jack shaft in order that the chains may run true4 ,,differential ,when a car takes a corner1 the outside wheels make a larger curve than the inside1 and cover a longer distance4 ,as the front wheels are loose on the axle1 they accommodate themselves to this2 but as both rear wheels are driven by the engine1 it is necessary to apply a device that will permit them to rotate at different speeds without interfering with their driving the car4 ,this is accomplished by means of a compensating and differential gear4 ,to understand the necessity for a differential1 stand behind a wagon1 with one hand on each tire2 push1 and if the vehicle is steered straight ahead1 the hands will move ahead equally2 but if the vehicle turns1 the hand on the outside wheel will move ahead faster than the other4 ,now take a stick1 and run it through the rear wheels so that it bears against the spokes2 press it forward from its center1 and if the vehicle moves straight ahead1 the stick will go forward equally2 but if the vehicle turns1 the outside end of the stick will go ahead faster and farther than the other1 although the pressure is being applied to its center4 ,illustration3 ,,bevel ,,gear ,,type ,,spur ,,gear ,,type ,,fig4 #dc4--;,,differentials4 ,in applying a simple form of differential the axle is divided into two parts1 to the inner ends of which are fitted bevel gears1 these being held at a fixed distance apart by the construction of the housing 7,fig4 #dc74 ,between the bevel gears and in mesh with both of them are small bevel gears1 or pinions1 which may revolve on short studs carried on a ring so that they are a fixed distance apart4 ,when the ring is revolved it carries with it the studs and pinions4 ,the ring forms a housing that incloses the differential1 and is driven by the single chain or driving shaft4 ,to understand the action of the differential1 imagine the rear wheels of a car to be jacked up clear of the ground so that they are free to revolve1 and the housing to be revolved by hand4 ,as it turns1 the driving wheels will turn also1 for the resistance to each is the same1 and the pinions1 being in mesh with both bevel gears1 cannot revolve on their studs4 ,if one of the wheels is now held stationary and the housing revolved1 the bevel pinions will revolve on their studs1 and roll around on the stationary gear2 this will drive the gear of the free wheel at twice the speed of the housing4 ,the revolving of the housing in the first instance caused the wheels to turn equally at the speed of the ring1 and in the second permitted one to remain stationary while the other turned at twice the speed of the housing1 the speed of the latter being unchanged4 ,the first is the effect when the car moves straight ahead1 and the second the result if the car could make so short a turn that it would pivot on one wheel4 ,with the wheels jacked up1 hold one hand lightly against one of the wheels1 so that while it may turn1 there is more resistance to it than to the other4 ,if the housing is now revolved1 the bevel pinions will revolve on their studs1 and roll slowly around the gear of the wheel that presents the resistance1 the free wheel being revolved at a higher speed than the housing4 ,this is the condition when the car takes a corner1 for there is then more resistance to the inside than to the outside wheel1 and it slows down2 this will start the pinions revolving on their studs1 and they will drive the outside wheel correspondingly faster4 ,with the housing revolving at a fixed speed1 the outside wheel will revolve as much faster as the inner wheel is revolving slower2 for an illustration1 if the housing makes fifty revolutions a minute1 and the inner wheel is slowed to forty1 the outer will be driven at sixty revolutions4 ,if one wheel of a jacked-up car is revolved by hand1 the other wheel will revolve in the opposite direction4 ,this is caused by the housing remaining stationary and the pinions being revolved on their studs by the turning of the wheel1 the movement being transmitted to the free bevel gear and wheel in the reverse direction4 ,the bevel gear differential described was the early type1 but a more recent design employs spur gears4 ,the axle ends carry spur instead of bevel gears1 these being in mesh with other spur gears that are long1 but of small diameter4 ,these small gears are in pairs1 as shown in ,fig4 #dc1 being in mesh with each other at their inner ends1 and each member of a pair meshing with one of the axle gears4 ,the small gears revolve on studs supported by the housing that is revolved by the drive1 the studs in this case being parallel with the axle instead of at right angles to it1 as are the studs in the bevel-gear type4 ,if the small gears meshed only with the axle gears1 and not with each other1 revolving the housing would cause them to roll around the axle gears1 all rotating on their studs in the same direction1 and the axle gears remaining stationary4 ,being in mesh with each other1 they cannot revolve in the same direction1 for when two gears are in mesh they must revolve in opposite directions4 ,thus the small gears cannot roll around on the axle gears when the housing is revolved1 and if there is equal resistance to the turning of the wheels1 the small gears will not revolve on their studs1 but will carry the axle gears with them4 ,if the car is turning a corner1 the greater resistance to the inner wheel will cause the small gears to revolve on their studs1 rolling around the resisting gear and driving the other correspondingly faster4 ,on cars with double-chain drive1 the differential is fitted to the jack shaft1 and of course receives the drive from the change-speed mechanism through its housing4 ,both the driving-shaft and double-chain drive have points of advantage and of weakness1 and each type has its advocates4 ,for the double chain1 great strength can be claimed with light weight1 as the axle is in one piece1 and perfectly adapted to support the car4 ,against it is the difficulty of keeping the chains properly lubricated1 and their consequent wear and stretching4 ,the driving-shaft type has the advantage of the perfect lubrication of the parts1 for all may be inclosed and running in oil or grease2 the rear axle must be divided1 however1 which requires it to be heavily braced in order that the weight imposed on it may not bend or spring it out of line4 ,where a bent dead axle can be straightened by a blacksmith1 a similar condition in a live axle requires the services of an expert mechanic2 on the other hand1 bevel gears make less noise than chains4 ,,driving-,,gear ,,ratios ,even when on the direct drive1 the crank shaft makes more revolutions than the rear wheels1 in order that the momentum of the moving parts of the engine may be sufficient to keep the car in motion4 ,on shaft-driven cars1 the bevel on the driving shaft has fewer teeth than that on the axle1 so that it revolves more than once to one revolution of the axle4 ,on chain-driven cars1 the driving sprockets are smaller than those driven4 ,this driving-gear ratio1 as it is called1 varies from one and a half to three and a half1 or1 in other words1 the wheels revolve once while the driving shaft or sprocket makes from one and a half to three and a half revolutions4 ,other conditions remaining equal1 a higher driving gear gives the car lower speed1 but greater ability in hill-climbing and the traversing of heavy roads4 ,,chapter ,x ,,running ,,gear ,the steering of a motor car1 or the change in the direction of its movement1 is effected by changing the position of its steering wheels1 usually those in front1 in relation to the rear wheels4 ,in a horse-drawn vehicle1 the axles are parallel when it is moving straight1 as are also the planes of its front and rear wheels4 ,to turn the vehicle to one side or the other the front axle is swung so that it is out of parallel with the rear axles1 the vehicle turning to the side on which the axles would meet if they were extended4 ,this construction requires the wheels to run loose on the axle1 and the axle to be permitted to swing on the pivot by which it is attached to the body of the vehicle4 ,such a construction would be impracticable for an automobile1 because the weight resting on the front axle would require the pivot to be of greater strength and stiffness than could be conveniently obtained1 and because of the effort that would be necessary to swing the axle in steering4 ,the front axle of an automobile is stationary1 and the steering effect is obtained by pivoting short pieces to its ends1 these carrying the wheels4 ,from these pivoted ends1 called knuckles1 extend short steering arms1 which are connected by a drag link1 so that moving the drag link moves the pivoted ends of the axle and the wheels to correspond 7,fig4 #dd74 ,illustration3 ,,fig4 #dd4--,,two ,,arrangements ,,of ,,the ,,drag ,,link4 ,illustration3 ,,fig4 #de4--,,steering ,,principles4 ,for a wheel to follow a curved path without slipping1 it must be at all times tangent to the path1 and will be perpendicular to a radius of the curve at that point4 ,the front axle of a horse-drawn vehicle points toward the center of the circle on which the vehicle may be turning and forms part of the radius1 the wheels1 of course1 being perpendicular to it 7,fig4 #de74 ,as the main part of the front axle of an automobile is stationary1 only its pivoted ends may point to the center of the circle1 and this must occur in order that the wheels may be tangent to the curve 7,fig4 #de74 ,both axle ends point to the center1 but along different radii2 if both pointed along the same radius1 it would necessitate their being in line with the stationary part of the axle1 which then also would be part of the radius4 ,as the axle ends are in line with different radii of the same curve1 it follows that the wheels are perpendicular to different radii1 and not parallel with each other1 a condition impossible in horse-drawn vehicles4 ,the front wheels of an automobile are parallel with each other when the axle ends are in line with the stationary part1 but go out of parallel as soon as they are at an angle with it1 as is the case when the car takes a curve4 ,if the steering arms projected from the knuckles at right angles to the axle ends on which the wheels revolve1 moving the drag link would move each knuckle through an equal angle1 and the wheels would be parallel at all times2 this is prevented by so constructing the knuckles that the steering arms incline toward each other1 with the result that when the drag link is moved1 one of the wheels swings through a greater angle than the other1 the difference between the angle of each steering arm and the stationary part of the axle increasing with a greater movement of the drag link4 ,the control of the drag link is obtained either by a steering lever or wheel4 ,when the steering lever is moved by the driver1 the drag link is moved to correspond by a connecting rod1 and this type is usual in small cars4 ,it is impracticable for heavy cars because it is reversible2 that is1 the moving of the steering wheels moves the lever1 and a firm grasp is required to prevent the shock of striking a stone or rut from tearing the lever from the hand and changing the course of the car4 ,the irreversible type is used for all but the lightest cars1 and while it permits the driver to change the direction of the front wheels it prevents any movement from being transmitted from the wheels to the steering wheel or lever4 ,the screw-and-nut type of irreversible steering mechanism 7,fig4 #df1 ,b7 consists of a heavy screw attached to the lower end of the shaft that revolves when the driver turns the steering wheel4 ,the screw passes through a nut that is held in guides so that it cannot revolve1 and is therefore moved up or down when the screw is turned by the steering wheel4 ,from the nut extends an arm that is connected to the drag link1 so that its movement is transmitted to the wheels4 ,the turning of the steering wheel thus moves the nut and the front wheels1 but a movement of the front wheels from any other cause is prevented1 because no pressure on the nut can revolve the screw4 ,another type is the worm-and-worm wheel1 or worm-and-segment 7,fig4 #df1 ,a71 which1 while of different construction1 depends on the same principle that the movement of the worm or screw can move a worm wheel or nut in mesh with it1 but the movement cannot be reversed4 ,illustration3 ,a ,b ,,fig4 #df4--,,steering ,,mechanisms4 ,a1 ,worm and worm-wheel steering gear2 ,b1 nut and screw steering gear4 ,the stationary part of the front axle of an automobile is usually a forging1 and must be of considerable strength in order to support the weight imposed upon it by the engine4 ,it is usually bent down in the center1 in order that it may be the lowest point of the mechanism1 thus to receive possible blows of stones or other high points of the road that would cause serious damage should they strike the crank case or fly wheel4 ,,brakes ,the brakes used in controlling the speed of an automobile may be as many as four in number1 and there should be at least two1 for on them depends the safety of the car4 ,brakes are of two types1 expanding and contracting1 and usually operate through the friction between a drum and a band that surrounds it1 or blocks that press against its inner surface4 ,the band or contracting brake may be either single- or double-acting1 the latter being by far the better4 ,in a single-acting band brake 7,fig4 #dg7 a flexible steel band surrounds the drum1 one end being made fast to the frame of the car or some other stationary part1 and pressure applied by drawing the free end4 ,the friction caused by the binding of the leather or fiber lining of the band on the drum restrains the movement if the drum is revolving in the opposite direction to the pull1 but there is little effect if the revolution is in the same direction as the pull4 ,in the double-acting type1 both ends of the band are pulled1 and the drum is prevented from revolving in either direction4 ,the single-acting type would be satisfactory when the car moves forward1 but will not hold it from running downhill backward1 while the double-acting brake holds it in either direction4 ,the expanding brake usually consists of two bronze shoes1 of such shape that they fit the interior surface of the drum4 ,the shoes are pivoted together at one end1 and so arranged that the pull of the brake pedal or lever expands them1 binding them against the drum 7,fig4 #dg74 ,when pressure is not being exerted1 a coil spring1 not shown in the diagram1 holds them together and out of contact with the drum4 ,illustration3 ,,single ,,acting ,,band ,,brake ,,double ,,acting ,,band ,,brake ,,internal ,,expanding ,,brake ,,fig4 #dg4--,,three ,,varieties ,,of ,,brakes4 ,brake drums are usually attached to the spokes of the rear wheels1 and one drum often serves for both an expanding and a contracting brake4 ,brake drums are also applied to the jack shaft1 or to an extension of the countershaft of the change-speed mechanism4 ,it is usual to have one set of brakes controlled by a foot pedal1 and another1 called the emergency brake1 by a lever at the side of the car4 ,the foot brake1 or running brake1 is always connected to the clutch1 so that applying it throws out the clutch4 ,the emergency brake is also connected in the same manner in some makes of automobiles1 but this is not recommended1 for if it is necessary to stop the car when going uphill1 the brakes must be released before the clutch can be thrown in1 and the possibility of the car starting downhill backward before power can be applied1 the chance of stalling the engine through this1 and the danger of the combination to any but an experienced driver1 make it advisable to have the emergency brake separate from any connection with the clutch4 ,band brakes are usually lined with leather1 to increase the friction between the band and the drum1 and this often gives rise to troubles in the burning of the leather when the brake is applied for a considerable period1 as in the descent of a long hill4 ,the emergency brake has advantages in that it operates through the friction of metal against metal1 but excessive heat from continued application may be enough to melt the metal and fuse together the shoe and drum4 ,for long descents1 it is well to use the motor as a brake1 for it is logical to consider that the means of propulsion may also be the means of retarding1 as the wind that urges a sailboat forward may also bring it to a stop4 ,it is obviously impossible to reverse the motor or gears1 but by switching off the ignition circuit and throttling down1 the forward movement of the car is caused to operate the motor1 and the work necessary in driving the motor as an air compressor is sufficient to check the speed4 ,the effect is so great that if the low-speed gears are engaged1 the car will be brought to a stop even on a steep hill4 ,another advantage of this course is that it gives the motor an opportunity to cool1 which is often necessary after a long ascent4 ,in case of the failure of the brakes to operate1 which may result from poor adjustment or worn bands and shoes1 the speed may be checked by throwing out the clutch1 switching off the ignition1 engaging the intermediate speed gears1 and letting in the clutch very slowly4 ,great care must be taken that the clutch is not permitted to bind suddenly1 for that would probably result in the stripping of the gears4 ,if the low-speed gears are engaged1 the checking would be so sudden1 no matter how slowly the clutch might be engaged1 that the shock would probably throw the passengers from their seats4 ,the failure of the brakes when descending a hill produces a condition that requires skill and coolness1 and danger can only be averted by a steady hand and a clear head4 ,brakes applied to the rear wheels must have an equal grip on each1 for if one binds more tightly than the other1 the car will have a tendency to skid1 or slide sideways4 ,in the best cars this is taken care of by an equalizer1 in which the pull of the lever or pedal is not applied directly to the brakes1 but to the center of a bar1 each end of which is connected to one of the bands or shoes4 ,the lever action of this bar distributes the pull equally between the two brakes1 and unless there is a great difference in the grip on the two drums1 as might be the case if one were oily and the other dry1 the effect will be the same on both sides4 ,,tires ,for low speeds1 solid tires give good results in traction and the absorption of jolts from small obstacles1 but for anything above six or eight miles an hour1 pneumatic tires are a necessity in preventing the rapid shaking to pieces of the mechanism4 ,a hard tire touches the ground at but one point1 and its grip on the road will be much less than that of a pneumatic tire which1 being slightly flattened by the weight it bears1 presents an oval or elliptical surface to the road4 ,while a pebble will force a solid tire to roll over it1 it will sink into a pneumatic tire1 and the jolt that it might cause will be entirely absorbed4 ,pneumatic tires are formed of alternate layers of heavy canvaslike fabric and soft rubber1 and the processes through which they are put in manufacture are supposed to effect their perfect combination2 but as it is not the nature of rubber to be absorbed by the fabric1 the layers are only bound together by its tenacity4 ,the bending of the sides of the tire under the weight of the car tends to separate these layers1 and water or dirt entering between them through cuts quickly brings ruin2 it is obvious that the less the sides bend1 the smaller will be the opportunity for the layers to work apart4 ,a pneumatic tire should always be pumped as hard as possible1 so that it stands up practically round under a loaded car4 ,while the car will ride a little harder under these conditions than when the tires are soft1 there will be greater resistance to punctures1 and the life of the tires will be increased4 ,the normal wear to a tire should give it a smooth surface1 but if it is noticed that the tread is rough and uneven1 it may be taken for granted that the wheels do not run true4 ,rear wheels will be thrown out of true by the springing or bending of the axle1 and front wheels also from this cause1 but more probably from faulty adjustment of the steering mechanism or the bending of the drag link or steering arms4 ,the grip of the tire on the road is much affected by the nature of the surface1 the traction on dry macadam being much greater than on wet asphalt4 ,when the pull of the engine on the wheel exceeds the grip of the tire on the road1 there will be a slip1 and the wheel will revolve without moving the car4 ,this will wear the tread of the tire far more rapidly than will ordinary running4 ,the better the traction of the tires on the road surface1 the less will be the tendency of the car to skid or slide sideways1 and less power will be lost through the slipping of the wheels4 ,to reduce the chance of slipping1 because of wet asphalt or muddy roads1 various devices are in use1 all of which encircle the tread of the tire1 and present a rough surface4 ,the form in most general use consists of chains that fit across the tread1 these being detachable and used only in case of necessity4 ,while it is often done1 it is nevertheless bad practice to apply chains or other antiskid devices to only one of the rear wheels instead of to both1 for it increases the diameter of the wheel and makes a difference in the resistance against the wheel1 causing the differential to operate at all times4 ,the differential is not constructed to operate steadily1 and will wear rapidly if forced to do so4 ,,springs ,illustration3 ,,fig4 #dh4--;,a1 ,full elliptic spring2 ,b1 half elliptic spring4 ,in addition to tires1 an automobile is fitted with springs1 which are necessary to absorb the shocks and jolts that are too great to be taken up by the tires4 ,these are usually full or half elliptic 7,fig4 #dh71 and made of flat plates1 or leaves1 of different lengths1 the small being placed on the large1 and all bound together at the center4 ,the combined action of the springs and tires permits the frame and body of the car to move in a nearly straight line1 while the wheels and axles follow the inequalities of the road4 ,when springs break1 as is frequently the case1 it is from the rebound of the body that results when the wheels drop into a deep hole1 the upward movement separating the leaves1 and the entire strain coming on the long leaves alone4 ,to prevent this1 shock absorbers are recommended1 which permit the springs to have a certain amount of action1 but check them if they tend to expand or compress to too great an extent4 ,they act either by the friction between metal plates and washers1 or by air or oil in a cylinder that permits a piston to move freely to a certain degree1 but presents resistance to a greater motion4 ,shock absorbers are placed between the axles and frame1 and there should be four1 two to each axle4 ,,distance ,,rods ,as the springs are placed between the axles and body and are flexible1 it is necessary to provide some method of preventing an obstruction in the road from twisting the axle1 as might result if one wheel struck heavy sand or a stone while its mate was on good surface4 ,a twist of this sort would throw the axle out of line with the drive and bind the chain or driving shaft4 ,illustration3 ,,fig4 #di4--;,,distance ,,or ,,radius ,,rods4 ,to prevent this1 radius or distance rods are attached to the axle1 one on each side1 extending to a point well forward on the frame 7,fig4 #di74 ,these rods are pivoted to the frame1 and have a loose joint on the axle1 so that the latter is free to move up and down1 but prevented from moving forward or back4 ,distance rods are adjustable1 and on chain-driven cars serve to adjust the chains1 which are tightened by lengthening the rods and slackened by shortening them4 ,,chapter ,,xi ,,troubles ,practice and experience are the best instructors in keeping the car running1 and the operator quickly acquires the ability to recognize the source of trouble from the action of the engine in failing to deliver power1 or from the manner in which it stops4 ,each part of the mechanism may be counted on to give trouble1 and the possibilities are numerous1 but in general it may be said that an interference with the proper operation of the engine may be laid to the failure of the ignition system or gasoline supply1 a defect of the combustion space in not retaining the pressure1 or the overheating of the engine4 ,,ignition ,,troubles ,the ignition system is the greatest producer of trouble1 and the reason is usually difficult to locate4 ,any interference with the flow of the current1 or leaks by which it evades passing over the entire circuit1 will cause irregular running or the stopping of the engine1 and the circuit must be maintained in the best possible condition in order to prevent these as much as possible4 ,the wires should be well insulated1 the insulation of the secondary circuit being heavier than that of the primary because of the higher pressure of the current that must be retained4 ,the constant vibration to which the wires are subjected requires the use of cable composed of a number of strands of fine wire rather than a single heavy wire1 for the latter is much more liable to be broken2 but in securing the end of a cable under a nut1 great care must be exercised that all of the strands are bound4 ,a single strand is hardly noticeable1 but if it comes into contact with uninsulated metal1 it will permit the current to leak4 ,in making connections1 the best plan is to solder the end of the cable to a copper or brass terminal which holds the strands secure1 and gives a firm bearing for the nut4 ,before making connections the terminals should be scraped bright1 and after running the nuts down firmly1 covered with vaseline to prevent corrosion4 ,corrosion of copper or brass produces a greenish deposit 7copper sulphate7 which is an insulator1 and when it forms between the terminals of the conductor it produces high resistance1 cutting down or even preventing the flow of current4 ,a worse effect of corrosion is to bind the nuts on the screws1 preventing their removal4 ,a loose connection presents resistance to the flow of current1 and the current will flow irregularly1 as the vibrations bring the terminals together or separate them4 ,a wire broken at a terminal is easily seen1 but when a break occurs inside of the insulation1 it is more difficult to detect4 ,when a broken wire is suspected1 its circuit may be located by testing1 and new wires laid1 one length at a time1 until the faulty one is replaced4 ,it is poor economy to use cheap wire1 for the best is none too good for the hard use to which it is put4 ,the wearing away of insulation by chafing will produce a short circuit1 and the wires should be prevented from coming into contact with any part of the car or engine in such a manner as to give this result4 ,,the ,,battery ,when a battery is exhausted1 or nearly so1 it will not magnetize the core of the coil sufficiently to induce a current that will give a strong enough spark to ignite the mixture4 ,the length of time that a battery should last1 or the mileage that it should give1 is learned from experience1 and when it is exhausted in less time there is evidence that it has either been short-circuited or that the current has been used too extravagantly4 ,the extra source of current that should be provided should not be switched into circuit until the short circuit that exhausted the regular source has been located and removed1 or there will be a further waste of current4 ,it occasionally happens that through carelessness the battery is so connected that one of the cells is reversed1 in which case the current will be reduced by the loss of the current from two cells1 for the energy of the reversed cell will neutralize that of another4 ,if both sets of battery have become exhausted by short circuit1 current for further running may be obtained by connecting the two sets together in multiple1 supposing that each set is1 as is usual1 connected in series4 ,an apparently exhausted dry battery will recuperate1 or pick up1 if allowed to stand1 but a storage battery that shows #a4h volts or less for each cell should be immediately recharged1 for further use will cause fatal injury4 ,,the ,,magneto ,the principal troubles that come to magnetos are due to lack of lubrication and the weakening of the permanent magnets4 ,the clearance between the armature and the pole pieces between which it revolves is very small1 and even slight wear of the bearings through insufficient lubrication will permit the armature to touch4 ,the oil cups with which the bearings are provided must be kept filled1 or if the parts are connected to a mechanical lubricator1 the proper adjustment must be maintained4 ,when a magnet is permitted to stand without a piece of iron connecting the poles1 the magnetism will dissipate2 to prevent this1 a bar of soft iron1 called a keeper1 is placed across the poles1 the magnetic lines of force flowing through it from one pole to the other1 and the strength being retained4 ,the permanent magnets forming the field of a magneto are very strongly magnetized1 and the proportion of the strength lost through misuse will be large1 resulting in their being weakened to such an extent that the current produced will not be sufficient for ignition purposes4 ,these magnets can be re-magnetized by the makers when this occurs1 the magneto regaining its current-producing ability4 ,the strength of the magnets will be retained for a much longer period if1 when the car is standing1 the armature is in such a position that it acts as a keeper2 this will occur when its iron core is horizontal4 ,as the armature will be in this position when the current is being produced1 it is only necessary to bring the engine to a stop at the point when one of the pistons is approaching the end of a compression stroke4 ,on leaving the car1 the low speed should be engaged and the clutch withdrawn2 the engine may be cranked slowly1 and the armature held in position by throwing in the clutch to hold the crank shaft when compression is nearly complete4 ,it is most inadvisable to take a magneto to pieces without an exact knowledge of its construction4 ,except for lubricating the bearings1 it is best to leave it entirely alone4 ,in setting a magneto1 it must be remembered that it is not delivering current continuously1 and that when the iron core of the armature is parallel to the poles of the magnets no current is produced4 ,the greatest strength of current is delivered as the core moves into a vertical position1 and revolving the armature by the fingers will show this1 for during part of a revolution it will turn easily1 and during the rest of the revolution there will be resistance4 ,the engine should be cranked until a piston is near the top of a compression stroke2 holding it there1 the magneto gear may be meshed with that on the half-time or crank shaft in such a manner that the armature core has moved a trifle past the vertical position4 ,this will result in the production of a current at the instant that it is necessary for the ignition of the charge4 7,see ,appendix47 ,,the ,,coil ,there is always a small spark between the vibrator contacts of a coil1 and in time the platinum will be burned and corroded1 the oxide that forms being an insulator and preventing the flow of the current4 ,in such a case the points may be smoothed with a fine flat file and polished on a strip of leather1 or if too far gone for this1 may be renewed by soldering a short length of platinum wire to the adjusting screw and a plate of the same metal to the blade4 ,while this job is a delicate one1 it is not beyond the range of a careful amateur4 ,when the insulation of the coil or condenser breaks down1 as may result from overwork or long use1 it should be returned to the maker1 for the construction of a coil is exceedingly delicate1 and repairs on it require expert workmanship4 ,it is not advisable to take the coil apart in any way1 beyond the vibrator parts1 for inexperienced handling may injure it beyond repair4 ,,the ,,spark ,,plug ,the spark plug is a frequent source of trouble1 for the insulation may break down1 or a carbon deposit may form between the points1 either fault permitting the current to pass without jumping the gap4 ,plugs should be so made that when the parts are screwed together the strain will not come against the insulation4 ,porcelain insulation is brittle1 and may be cracked inside the sleeve1 the damage not showing on handling and inspection1 but being sufficient to permit the spark to pass inside of the sleeve instead of between the points4 ,mica insulation is usually formed of a large number of washers squeezed together under great pressure1 but the action of the heat and the presence of oil will frequently cause the layers to separate1 permitting a short circuit4 ,the carbon deposit that fouls and short-circuits spark plugs results from a rich mixture1 or overlubrication1 and this should be prevented by proper adjustments4 ,under the intense heat the carbon bakes hard1 and can be removed only by scraping or by the action of strong ammonia or gasoline4 ,as in scraping the smooth surface of the insulation may be scratched 7which would give a rough surface to which a fresh carbon deposit would cling more tightly71 the removal of the deposit by ammonia or gasoline1 applied with a stiff brush1 is recommended4 ,the points between which the spark passes should be about one thirty-second of an inch apart4 ,after long use1 the corrosion due to the heat of the spark will increase this distance1 when the points should be bent together4 ,the high compression through which the spark is required to pass presents greater resistance than air at atmospheric pressure1 practically in proportion to the pressure1 and a current that will produce a spark outside of the cylinder may not have sufficient pressure to give a like result when the engine is running4 ,if the pressure of the compression is four times that of the atmosphere1 the current should be able to produce a spark four thirty-seconds1 or one eighth1 of an inch long outside of the cylinder1 and for safety this should be increased four-fold4 ,,the ,,igniter ,the stationary point of the igniter is carried on the end of a screw that passes through the cylinder head or wall1 and by means of this screw its position in relation to the moving point may be altered as desired4 ,the distance between the points when they are separated should be about one sixteenth of an inch2 more than this will result in the formation of a longer spark between them1 and as the passage of the spark through the high resistance of the compressed charge will produce great heat1 the igniter points will be burned and corroded more than need be4 ,the adjustment may be made by loosening the lock nut on the stationary point1 and running the screw down until the stationary point is in contact with the movable when the latter is acted on by the cam4 ,the lock nut should be run down until it bears lightly against the cylinder and the point then unscrewed1 the lock nut being carried with it1 until the latter is about one sixteenth of an inch away from the cylinder4 ,this gives a corresponding distance between the igniter points1 and running the lock nut down firmly will secure it4 ,the tappet spring should be of considerable strength in order to snap the movable point from the stationary when the tappet ceases to act4 ,too great strength will bring the movable point against the stationary with such force that the platinum plate that it carries will be battered out of place4 ,the principal difficulty that is encountered is the corrosion of these points1 the flow of the current being decreased or stopped by the insulating film that covers them4 ,the blow with which the two come together tends to knock this off and to keep the surfaces flat1 but when they become badly worn and pitted they must be filed smooth4 ,the bearing in the cylinder wall in which the movable point rocks is made after the manner of a valve2 the opening must be tight in order to prevent the leakage of compression1 but sufficiently free to move as the cam acts on the tappet4 ,this joint cannot be lubricated with oil because of the heat1 and the two parts must therefore be kept as smooth as possible4 ,to attain this result they are ground together as engine valves are ground4 ,,the ,,timer ,the spring that keeps the revolving part of a timer in contact with the stationary part must be of sufficient strength to squeeze out the vaseline with which the timer is packed1 as otherwise the grease will form an insulating film between them1 preventing the flow of the current4 ,the timer must be securely attached to its shaft1 for if it is loose the contacts will be made at the wrong time1 and the sparks will not occur in the combustion space at the correct intervals4 ,all of its parts and connections should be as firm as possible4 ,the rods with which the stationary part is connected to the control lever on the steering column should be provided with adjustments by which lost motion due to wear may be taken up4 ,there are usually several joints in these rods1 all of which may wear loose1 and if there are no means by which they may be kept tight1 the lever will move a considerable distance before the timer will respond4 ,it is often possible to remedy this by placing coil springs in such positions that they take up the lost motion4 ,a timer should be so set on the half-time shaft that the revolving contact is just touching the stationary contact when the piston is at its highest point in the cylinder on the compression stroke1 the control lever being in nearly its most retarded position4 ,as dirt will interfere with the action of a timer1 the cover should always be in place and tightly secured4 ,,the ,,secondary ,,distributer ,a secondary distributer will give trouble through loose contacts1 dirt1 or the splitting of the spark1 the effect of the last being the passing of the spark from the revolving part to two or more contact points instead of but one4 ,particles from the carbon brush in wearing off may stick to the insulating ring between the contacts and form a path1 or a strand of wire may project1 producing the same result4 ,,the ,,switch ,loose switch parts will prevent the flow of the current or give a vibrating contact1 and should be frequently looked after4 ,if the switch is mounted on metal1 as is occasionally the case1 a loosening of the parts or the wearing of the insulation will result in a short circuit that is difficult to locate because the good condition of the switch is usually taken for granted4 ,,gasoline ,,troubles ,commercial gasoline is frequently dirty1 carrying particles of matter that will stop the fine passages and openings of the carburetor1 or containing water1 the presence of which will prevent the proper operation of the engine4 ,dirt may be removed by the use of a strainer made of fine wire gauze1 and water may be separated by filtering the liquid through chamois skin1 the gasoline passing through and the water remaining4 ,it is advisable to have a strainer and trap placed in the piping that connects the tank with the carburetor to form the lowest point of the system1 the gasoline passing through it and being cleansed of dirt and water4 ,,the ,,tank ,the tank of a gravity feed system is always provided with a small hole or vent1 usually drilled through the filling cap1 through which air may enter to replace the gasoline that is drawn off in the running of the engine4 ,if this hole becomes plugged with dirt1 the escape of the gasoline will reduce the pressure in the tank to such an extent that further flow will be prevented1 and the engine will stop with all of the symptoms of a lack of gasoline4 ,on opening the tank for the purpose of investigation1 the air supply will be renewed1 and the engine will again run1 to stop slowly as before4 ,clearing the hole will relieve the condition4 ,this vent may also cause trouble in permitting water to enter and contaminate the gasoline1 this being liable to happen when the car is washed4 ,the pipe by which the gasoline flows from the tank to the carburetor should project slightly above the bottom of the tank1 to prevent sediment from being drawn into it4 ,as gasoline rots rubber rapidly1 hose should never be used to conduct it1 nor should joints be packed with rubber4 ,copper and brass are attacked by gasoline less than other metals1 and should always be used in preference to iron1 which is corroded by the liquid4 ,joints may be made tight by the use of shellac or soap4 ,,the ,,carburetor ,besides the possibility of getting out of adjustment1 the greatest trouble with a carburetor comes from the clogging of the passages and openings with dirt4 ,when dirt enters1 it clogs the gasoline inlet valve and prevents it from seating properly1 the float chamber being flooded as a result4 ,when the level in the float chamber is raised1 more than the required amount of gasoline flows out of the spray nozzle1 and the mixture that is produced is too rich4 ,this will also result from the bending of the valve stem or the wearing of the seat1 either of which will prevent the proper shutting-off of the flow when the correct level in the float is reached4 ,a flooding float chamber may also be caused by a float that is out of adjustment on its stem or too heavy4 ,in the course of time the gasoline will cut a hole through the metal of a float and leak in1 and leakage will also occur if the soldered joints open1 the float then becoming too heavy and not closing the gasoline inlet valve at the correct time4 ,these holes will be too small to permit the gasoline to be poured out1 but by placing the float in hot water1 the gasoline will be evaporated and driven out as a gas4 ,in repairing a float1 as little solder as possible should be used in order that the weight of the float may not be greatly altered4 ,a cork float will become soggy and heavy if the varnish coating is damaged and the gasoline soaks in4 ,carburetors are built so that the float valve and spray nozzle may be easily cleaned1 for by withdrawing plugs fine wire may be run through them4 ,when a carburetor is taken apart for more thorough cleaning1 the position of the gasoline and air adjustments should be remembered1 in order that they may be replaced in approximately the correct positions1 thus saving time in making the adjustments that will be necessary4 ,the main air intake should be kept clean1 especially when it is covered with a wire gauze screen4 ,dirt will reduce the size of the opening1 and the air that enters will not be sufficient to give a mixture of the correct proportion4 ,the screen should be kept clean and free from oil1 for the latter is a dust collector4 ,,compression ,,troubles ,a leak in the combustion space will reduce the compression by permitting the fresh mixture to escape during the compression stroke1 and will also give an escape for the pressure resulting from the combustion1 the pressure on the piston being reduced in consequence4 ,the most frequent cause of leakage is worn valves1 the intense heat tending to warp the disks and to roughen their surfaces1 the exhaust valve being especially liable to this as it is surrounded by the hot gases during the time that it is open4 ,a badly fitting spark plug1 igniter stem1 relief cock1 or other opening into the combustion space will produce the same result4 ,whenever possible1 these parts should be fitted with copper asbestos washers1 which are soft enough to squeeze into the inequalities of the surface1 at the same time resisting the heat and pressure4 ,when piston rings or cylinder walls are cut or scratched by running without oil1 the pressure will escape into the crank case1 which1 while warm when the engine is running properly1 will be heated to a very noticeable degree under these circumstances4 ,the only remedy is the use of new piston rings and the reboring of the cylinder4 ,piston rings1 being of cast iron1 are brittle1 and must be handled carefully4 ,to place them in position in their grooves1 thin strips of steel1 like pieces of a hack-saw blade1 should be bound to the piston1 covering all but the lower groove4 ,the ring for this groove can then be slipped on1 and when it is in position the steel strips moved upward to expose the upper grooves1 one at a time4 ,piston rings are usually prevented from revolving around the piston by pins driven into the piston between their ends2 if these are not provided1 the turning of the rings will bring their ends into line1 and the pressure will leak through them4 ,the appearance of the rings is the best indication as to whether they are permitting leakage2 if they are tight1 they will be smooth and polished all around1 but if there is leakage1 they will be streaked with black carbon deposit4 ,other losses of compression may be due to a cracked piston1 cylinder head or wall1 the former being indicated by a hot crank case and the latter by the presence of water in the cylinder and crank case4 ,,cooling ,,troubles ,the failing of the cooling or lubrication systems will permit the engine to heat1 and if continued will produce disastrous results4 ,the radiator of a water-cooled engine should begin to heat shortly after the engine has started1 and will rapidly become warm all over1 thus showing that the water is circulating properly4 ,a failure of the circulation may be due to a clogged pump or passage1 and the cause should be located and removed without delay4 ,dirt in the water is the most usual cause of the failure of the pump1 and also of the stopping of the circulation in the gravity system4 ,a strainer should be fitted to the filling cap of the radiator to remove bits of wood1 leaves1 sand1 etc4 ,the connections of the water system are frequently made of rubber hose1 and this in rotting will free bits of rubber that will prevent the flow4 ,a difficulty occurring at the clamps that attach the hose to the metal pipes is the tearing off of a strip of the rubber lining1 which closes the passage after the manner of a valve4 ,the fan must be kept running correctly1 and if belt-driven1 the belt must be kept tight and the pulleys free from oil that would permit slipping4 ,water that has been heated freezes much more readily than water that has not1 and therefore the water system of an automobile must be carefully guarded against low temperatures4 ,a freeze of the water may crack the water jackets or split the radiator1 either of which will require the laying up of the car for repairs4 ,the best protection is to draw off the water if there is the slightest danger of freezing1 drain cocks being provided at the low points of the system for this purpose4 ,if this is not practicable1 a solution of four pounds of calcium chloride to the gallon of water1 mixed hot and allowed to cool1 may be used1 and it will stand a temperature of #ae ,f4 below zero without freezing4 ,the flanges or corresponding parts of an air-cooled motor should be kept clean1 for dirt will prevent the free radiation of heat4 ,a lack of lubricating oil1 either through the failure of the supply or the clogging of the pipes1 will cause the engine to heat and the piston to stick or seize4 ,when the car is new1 it is better to supply too much oil than too little1 but when the bearings have smoothed down the supply may be reduced4 ,the operation of the engine is the only indication as to whether it is receiving a proper amount of oil1 and rather than run the risk of underlubricating the piston rings and cylinder walls1 it is better to have enough to produce a faint smoke at the exhaust pipe4 ,this will show that the engine is receiving a little more than is necessary4 ,too much oil in the cylinder will foul the spark plug1 and as this would prevent the passing of the spark1 it is to be as much avoided as too little4 ,when the lubricator pipes are clogged1 the easiest method of clearing out the obstruction is to force air through them by means of a foot pump4 ,,chapter ,,xii ,,locating ,,trouble ,any interference with the regular running of an automobile is usually due to engine trouble1 and the nature of the irregularity or the unfamiliar noise will often give a clew to the experienced driver by which the fault may be located4 ,when the engine shows that something is wrong1 it is of little use to guess at the cause1 for changing an adjustment without being sure that it is the right thing to do will probably add to the difficulty instead of remove it4 ,the laying out of a system for the location of a fault is not difficult1 and its application simplifies matters when trouble is encountered4 ,by following a process of elimination1 the condition of the different parts of the mechanism can be learned1 and if on test the ignition system proves to be operating correctly1 the production of the mixture may be considered to be guilty until that in turn is shown to be innocent4 ,,make-,,and-,,break ,,ignition ,an engine equipped with the make-and-break ignition system is always provided with a conducting bar across the top or side of the cylinders1 called a bus bar1 connected with the source of current1 and each igniter is connected to it through a switch4 ,if one of the cylinders fires regularly1 it is an indication that the current is being generated properly1 and that no time need be wasted in examining the generator4 ,by means of the switches1 the igniters may be tested individually by cranking the engine with one switch closed and the others open4 ,when the clutch is disengaged the engine should run on one cylinder1 and if this is the case1 the igniter on the line of the closed switch is shown to be in good condition4 ,the opening of this switch and the closing of the next will give a comparison when the engine is again cranked1 and if explosions occur1 the igniter points may be adjusted until the two cylinders work equally well4 ,if the cylinder does not operate1 the stationary igniter point should be withdrawn and its contact examined2 this should be bright and clean4 ,the movable point should be worked by hand1 to determine whether the joint is stuck or the spring weak or broken4 ,if none of the cylinders show signs of explosions1 the connections should be examined to make sure that they are secure4 ,on systems employing a magneto alone1 the wiring consists of a single wire from the magneto to the bus bar1 and the shorter wires from there to the igniters4 ,these wires are clearly visible1 and any loose connections or broken wires may be detected without difficulty4 ,if the connections and wiring are in good condition1 the fault may be located in the magneto1 or1 if it has recently been dismounted1 its incorrect setting in relation to the crank shaft4 7,see ,appendix47 ,if the ignition system proves to be in proper working order1 attention may be paid to the carburetor and its connections4 ,,jump-,,spark ,,ignition ,in testing an engine fitted with the jump-spark ignition system1 the circuit should be closed and the crank shaft revolved twice1 attention being paid to the sound of the vibrators4 ,on a four-cylinder engine1 the timer makes four contacts in two revolutions of the crank shaft1 and if all of the vibrators are heard it is proof that the primary circuit is in good condition1 and not the seat of the trouble4 ,if only one of the vibrators buzzes1 the battery circuit may be considered to be working properly1 for otherwise no current could have passed to the coil box4 ,the trouble may then be identified as being in part if not altogether in the adjustment of the vibrators of the dead coils1 their connections with the timer1 or in the timer itself4 ,one end of a short piece of wire should be touched to the timer binding post of one of the dead coils1 and the other to any metal part of the engine1 the lubricator1 for instance1 to form a short circuit through the primary circuit with the exception of the timer and its connections4 ,if the vibrator buzzes1 the trouble is not in the coil1 but in that part of the circuit cut out by the short-circuiting wire4 ,the same piece of wire may be used to bridge across to any metal part of the engine from the binding post on the timer at which the wire from the coil is connected1 and if the wire from the coil to the timer is in good condition1 the vibrator will again buzz1 showing that the fault must be in the timer1 for all other parts of the primary circuit of that particular coil have been proven to be working correctly4 ,a dirty or faulty contact in the timer1 or a loose connection1 will probably be the cause4 ,if the primary circuit is shown to be in good order1 attention may at once be given to the gasoline feed1 for while the secondary circuits have not been tested1 it is extremely unlikely that the spark plugs or their connections will prove defective on all four cylinders at the same time4 ,,the ,,carburetor ,touching the primer of the carburetor will show whether the gasoline flows to the float chamber1 for if it is present it will spurt out of the opening through which the priming stem passes4 ,if the air inlet is so arranged as to permit it1 gasoline dropping out of it when the carburetor is primed excessively indicates that the liquid flows out of the spray nozzle1 this part thus being shown to be clear4 ,if no gasoline shows around the priming stem1 the feed pipe or float valve may be suspected of being clogged1 it being taken for granted that there is gasoline in the tank and that the supply cock is open4 ,if it is found that gasoline is present in the air inlet1 and that the carburetor is damp with it when the primer has not been touched1 it indicates that the float chamber is flooded2 the carburetor should be taken apart for inspection and thorough cleaning4 ,,engine ,,will ,,not ,,start ,when the engine will not start on cranking it eight times or so1 it is useless to continue to crank it1 for there is every reason to believe that something is wrong4 ,too often the difficulty is in forgetting to switch on the ignition circuit or to open the gasoline feed4 ,cranking the engine slowly will not reduce the pressure in the inlet pipe sufficiently to draw out of the spray nozzle the quantity of gasoline required to form an inflammable mixture2 quick cranking is necessary4 ,too much priming will result in the formation of a rich mixture2 the gasoline should be permitted to evaporate1 or the carburetor drained1 and then primed gently4 ,the failure of an engine to start on a cold day may be due to the slowness with which gasoline evaporates when chilled4 ,as it is obviously most unwise to heat the carburetor with a flame1 the best thing to do in such a case is to pack it with cloths soaked with hot water4 ,a little gasoline squirted into the air inlet1 or cotton waste soaked with gasoline and held over the same opening1 will almost always permit the engine to be started2 another method is to squirt a few drops of gasoline into the cylinders through the relief cocks4 ,,engine ,,does ,,not ,,deliver ,,full ,,power ,regularly occurring explosions indicate that the cylinders are receiving the proper quantity of mixture1 and that the ignition is operating correctly4 ,if under these conditions the engine fails to deliver full power1 which is shown by the sluggish running of the car1 the trouble may be identified as the result of a condition by which power is absorbed between the engine and wheels4 ,this may be from a slipping clutch1 binding brakes1 or tight bearings1 these more probably on the wheels than on the change-speed mechanism or drive4 ,the brake rods may get out of adjustment1 or the spring stick1 with the result that the bands or shoes are in continual contact with the drums4 ,a simple test for the condition of the brakes is to push the car across the floor by hand2 it is not difficult to recognize unusual stiffness4 ,this test also applies to the wheel bearings4 ,engine or transmission bearings that are too tight will heat1 and a touch of the hand will show the presence of this condition4 ,a tight bearing should be permitted to cool before readjusting it and proceeding4 ,,weak ,,explosions ,regular but weak explosions may be due to too rich or too poor a mixture1 or to the escape of compression4 ,cranking the engine twice will produce a compression stroke in each of the four cylinders1 and if there is a leak1 the ease with which the piston in which it occurs may be pulled over dead center will show its presence4 ,a little soapy water around the spark plug1 relief cock1 or other opening into the combustion space will show the escape of compression in the formation of bubbles4 ,a hiss inside of the cylinder indicates a leaky piston ring1 or that the openings of the rings are in line1 and when this sound is sharp and clear1 the presence of a broken ring4 ,an additional proof of this is the undue heating of the crank case4 ,if the compression is correct1 the carburetor may be readjusted to improve the quality of the mixture4 ,a poor mixture may be due to the partial clogging of the spray nozzle or its passages1 and a rich mixture to the choking of the air inlet by dirt or dust1 this being especially liable to occur when the part is oily4 ,,missing ,,explosions ,the missing of explosions is a common failing of automobile engines1 and while it may be due to a variety of causes1 the most usual is that the spark does not pass4 ,it is not always an easy matter to determine which of the cylinders is missing2 if the missing is constant1 the coolness of the exhaust pipe of one as compared to the others locates the fault4 ,if the missing is not constant1 the difference in temperature will not be noticeable1 but the one at fault may be located by holding down all of the vibrators but one4 ,if the cylinder corresponding to the free vibrator runs steadily1 its vibrator may be held down and another released1 this being continued until the faulty cylinder is located4 ,the condition of the secondary circuit of this cylinder may be ascertained by disconnecting the secondary wire from the plug1 and holding it about a half inch away from the plug terminal while the engine is cranked4 ,if no spark passes when the timer makes contact1 the trouble is in either the wire or the coil2 if a spark shows1 it should be of good strength1 for a current that will produce a fair spark in the open may not have sufficient strength to produce a like result when under compression4 ,if a good spark shows1 the spark plug may be suspected of being fouled and thus short-circuited1 of having a breakdown in its insulation1 or of there being too great a distance between its points4 ,the threads wear a little each time that a spark plug is removed from the cylinder1 and in order to retain a gas-tight joint it is best not to unscrew the plug unless it is necessary4 ,if the secondary circuit is proven to be in good condition1 attention should be paid to the carburetor1 for a poor mixture1 or water in the gasoline1 will cause the engine to miss4 ,a badly fitting exhaust valve will permit the burned gases to be drawn back into the cylinder1 the fresh charge thus being weakened1 and as the valve will shift around on its seat1 this may happen irregularly4 ,missing will also be caused by a weak or broken inlet-valve spring1 or by the sticking of the inlet valve1 these conditions resulting in failure to retain the mixture in the combustion space during the compression stroke4 ,this pushing back into the inlet pipe of the charge will usually produce a popping or gurgling noise that is easily recognized4 ,,missing ,,at ,,high ,,speed ,if an engine runs well at low speed1 but misses when speeded up1 the trouble may be due to weak battery1 stuck vibrator blade1 or loose connections4 ,a battery that will produce a good spark at low engine speed may not be able to respond to the greatly increased demands of high speed1 and similarly1 at low speed the period during which the timer holds the circuit closed is longer than at high speed1 and the vibrator has more time to get into action before the circuit is broken4 ,a loose connection may be so shaken by the vibrations of high speed as to break the circuit4 ,,engine ,,starts ,,well1 ,,but ,,comes ,,to ,a ,,stop ,if the battery is nearly exhausted1 it will recuperate during a rest to such an extent that it will produce good sparks1 but as its condition of strength is only temporary1 the engine will slow down and come to a stop as the current fails4 ,this action of the engine may also be due to carburetor defects by which the vibrations of running either cause the flooding of the float chamber or the clogging of the spray nozzle1 the mixture in both cases becoming noninflammable2 the condition will also result from an air-bound supply tank4 ,,overheating ,it sometimes happens that the engine will continue to run after the ignition circuit is opened4 ,this may be due to a failure of the water circulation1 which is indicated by the low temperature of the radiator1 or by the low speed or stopping of the fan from a slipping or broken belt4 ,if the cooling system is working properly1 the lubrication must be investigated4 ,if the oil is flowing as it should1 the cause will be found in the formation of a carbon deposit in the combustion space1 fine points of which will become incandescent and ignite the mixture as it passes into the cylinder or as it is compressed4 ,a more unlikely fault may be that the points of the spark plug are fine enough to become heated in a similar manner2 modern plugs are made with points of such size that this possibility need hardly be considered4 ,this ignition of the mixture by other cause than the proper spark is termed preignition4 ,,engine ,,comes ,,to ,a ,,stop ,if the engine stops suddenly1 the fault will be found in the accidental opening of the switch1 or the breaking of a wire or connection4 ,an abrupt stop cannot be caused by anything but an interruption of the ignition circuit1 for the cessation of the gasoline feed will bring the engine to a stop slowly1 the gasoline in the float chamber and spray nozzle being sufficient to permit weakened explosions before the supply entirely fails4 ,a slow stopping of the engine from causes other than those previously mentioned may be laid to defective gasoline feed1 the emptying of the tank1 the clogging of the supply pipe1 float valve1 or spray nozzle1 or the closing of the supply cock from jolts and vibrations4 ,if the engine comes to a stop when there appears to be no fault with the explosions1 the cooling or lubricating systems may be at fault1 resulting in the heating of the cylinder to such an extent that the piston sticks or seizes4 ,excessive heat is proof of this1 the burning or 8frying0 of excess oil on the outside of the cylinder being an early warning4 ,a seized piston may be freed by injecting kerosene into the cylinder1 and cranking1 the cylinder first being given time to cool4 ,,noises ,the noises made by the engine when operating properly become so familiar to the careful automobilist that any other sound is recognized more by instinct than by attention4 ,faults will often make themselves known by noises1 and these may be broadly classified as pounds or knocks1 hisses1 squeaks1 and rattles4 ,a pound that occurs regularly may be due to a loose connecting rod or wrist-pin bearing1 and in this case will be heard once to every two revolutions of the crank shaft4 ,a pound that occurs oftener than this may be set down as a loose crank-shaft bearing1 or a loose or cracked fly wheel4 ,if often happens that a fly wheel in this condition will make itself heard1 while sufficiently tight to show no sign of the defect on casual inspection4 ,a hard metallic pound is caused by the combustion of the charge before the completion of the compression stroke2 this condition may result from preignition or from the spark being too far advanced4 ,if the latter is the case1 retarding the spark will stop the pounding4 ,hisses are due to leaks in the combustion space1 as already described4 ,squeaks indicate a dry bearing1 or a lack of lubrication in one of the moving parts4 ,the bearing may be detected by its heat4 ,a squeak of the leaves of a spring will often be difficult to trace and locate1 because of its irregularity4 ,rattles indicate that something is loose1 and should be located without loss of time4 ,all nuts and bolts should not only be tight1 but in addition secured in position by the use of lock nuts or cotter pins4 ,backfiring1 which is an explosion of the mixture in the inlet pipe or carburetor1 may be due to a stuck inlet valve that permits flame to pass and ignite the mixture before it reaches the combustion space1 but more probably either to ignition occurring so late that combustion is still occurring when the inlet valve opens1 or to preignition4 ,explosions in the exhaust pipe or muffler are due to the presence of unburned mixture1 which is passed out of the exhaust valve after ignition has failed1 and ignited by the heat of the exhaust pipe1 or by the hot gases from the next explosion4 ,,chapter ,,xiii ,,maintenance ,,and ,,construction ,in order that an automobile may be maintained at its highest efficiency1 a constant watch must be kept over all of its parts1 and repairs and replacements made as soon as the necessity is apparent4 ,a worn bearing or loose part may continue to operate1 but the wear will be far greater than would occur under normal conditions1 and may result in serious breakage4 ,a system of inspection to be gone through every time that the car is used will keep the driver informed as to its condition1 and it is best to form the habit of doing this at the end of a run rather than before1 for then the necessity for making readjustments or repairs will be fresh on the mind4 ,,inspection ,the condition of the ignition circuit and of the compression will be shown in revolving the crank shaft twice1 and the action of the carburetor may be ascertained at the same time4 ,pushing the car across the floor will show the presence of tight brakes or wheel bearings1 and the tires may then be examined for cuts4 ,beginning at the front of the car1 every bearing not fed by the lubricator should be oiled1 and all grease cups given a slight turn1 those that are empty or nearly so being filled4 ,while this is being done1 a watch may be kept for nuts and bolts that may have been loosened by the vibrations4 ,,washing ,the car should be washed with clear1 cold water only1 and mud floated off2 to remove mud by rubbing or any other method than sluicing it away by the action of a gentle stream of water will scratch the varnish and ruin the appearance of the car4 ,when clean1 the varnished parts may be dried with chamois or wash leather1 and the finish retained by a light coating of a good furniture polish1 which is to be immediately dried by rubbing4 ,the tires may be cleaned by sponging1 but water should not be allowed to settle in the bead4 ,on cars having the gravity system of gasoline feed1 the water should not be permitted to splash on the tank1 for it will enter through the vent4 ,water should also be kept from the upholstery1 for if it enters the folds and buttonholes it will cause rotting4 ,,the ,,tires ,light and heat are the worst enemies of rubber2 spare tires should be kept in a cool1 dark place1 and protected from dust and moisture4 ,french chalk1 or some similar preparation1 should be well dusted over the shoes and tubes1 and if the tubes are folded1 they should occasionally be opened and refolded in fresh places1 to prevent the formation of creases4 ,the spare tire that is carried on the car should be kept in a casing1 and because a dark surface will absorb more heat than a light1 the casing should be tan1 gray1 or white rather than black4 ,the casing should be as proof as possible against moisture1 but for safety should occasionally be removed and aired4 ,the position of the shoe in the holders should be changed every little while1 in order that the straps may not cut into the bead4 ,the tires on the wheels should receive care1 and when the car is left standing1 it should be in the shade whenever possible1 to protect them from the deleterious action of the sunlight in hardening the rubber4 ,they should frequently be examined1 and any cuts filled with strong cement1 for otherwise water and sand will work in to form blisters and to separate the layers of fabric from the rubber4 ,the cutting of tires can be reduced by withdrawing the clutch when crossing broken stones1 the car coasting over them2 driving the car over such a surface will force the tires against the sharp edges1 and cutting will result more surely than when the tire rolls over them4 ,,care ,,of ,,the ,,engine ,the carbon deposits that will form in the combustion space will in time tend to stick the piston rings in their grooves1 and this may be prevented by squirting a few drops of kerosene oil into the cylinders and cranking the engine to distribute it4 ,this should be done at the end of a run1 and the engine permitted to stand in that condition4 ,the first explosions will vaporize the kerosene and drive it off unless too much has been used1 when there will be a tendency to foul the spark plugs4 ,the lubricating oil should be drained out of the crank case every five hundred miles1 and the case washed out with kerosene before refilling it with fresh oil4 ,gasoline has too great a cutting action to warrant its use for this1 as it cleans down to the bare metal1 while kerosene removes the dirt and grease1 leaving a good surface4 ,the case should be filled with oil to such a depth that the connecting rods will dip into it from a half-inch to an inch4 ,the same should be done with the change-speed gear case every thousand to fifteen hundred miles1 for the particles of metal that will be ground from the gears will injure the teeth and bearings4 ,in refilling1 the smallest gear should project about an inch into the oil4 ,if the differential is packed in grease1 it will run for an entire season with one filling1 but if it runs in oil it should be cleaned and washed two or three times a year4 ,the bevel gear case of a shaft-driven car should receive the same attention4 ,,care ,,of ,,chains ,properly lubricated chains should run for at least a thousand miles without attention4 ,because of their exposed position they should be protected against undue wear1 and this is best attained by soaking them1 when thoroughly cleaned1 in melted tallow1 working each joint in order that the liquid may penetrate4 ,the chain should be hung up to cool and dry1 the surplus tallow being wiped off4 ,the hardened tallow in the joints will prevent grit from working in1 and is a lubricant as well4 ,to clean a chain1 soak it in kerosene1 working each joint to remove the grit4 ,the stretching of the chain may be taken up by lengthening the radius rods1 but when the stretching reaches a point that permits it1 the chain should be shortened by the removal of a link1 and the rods readjusted4 ,if a complete chain is not carried as a spare part1 the kit should always include a few extra links for emergency repairs4 ,these are not difficult to apply1 being secured in position by nuts instead of by burring over the ends of the rivets4 ,,valve ,,grinding ,to grind a pitted or worn mechanically operated valve1 the pressure should be released by compressing the spring and removing the key or other device by which it is held in place4 ,on removing the plug over the valve pocket1 the upper surface of the valve disk will be exposed1 and it will be found to be provided with a slot4 ,while many grinding pastes may be purchased1 good results will be obtained by mixing machine oil with flour of emery until it is thick4 ,plugging the opening from the valve pocket to the combustion space with cotton waste to prevent the paste from entering the cylinder1 spread it on the valve disk and seat1 and rotate the disk on its seat with a screwdriver1 preferably by means of a bit brace4 ,every little while the disk should be lifted and replaced on the seat in a new position1 in order to distribute the wear evenly1 and the grinding continued until a smooth surface shows all around both disk and seat4 ,it is not necessary to smooth the entire surface of the disk and seat1 for the pressure will be retained by a narrower surface4 ,an automatic valve may be removed from the cylinder by unscrewing or unbolting its cage1 and after releasing the spring the cage may be held in a vise while the grinding is performed4 ,after grinding1 all traces of the paste should be removed by washing with gasoline1 for any particles that remain will cause rapid wear4 ,when replacing the spring1 that of the mechanically operated valve will be found difficult to compress to the point at which the key or washer may be slipped into position1 and to simplify this many engines are built with a knob or boss on the cylinder to serve as a fulcrum by which a forked lever may be used4 ,if this is not the case1 the spring may be sufficiently compressed in a vise1 and bound endwise with wire to retain it1 the wire being cut when the spring and key are in position4 ,,care ,,of ,,steering ,,mechanism ,a failure of the steering mechanism will cause a wreck more surely and quickly than the breakdown of any other part of the car1 and the best protection is absolute knowledge that it is in perfect condition4 ,all joints should be kept well lubricated1 and protected from dust2 the leather protectors that are furnished do not accomplish this any too well1 but they are much better than nothing1 and if the joints are packed with grease before applying them1 the results will be good4 ,while guarding against stiffness1 there should be very little play or lost motion in the mechanism1 and the parts should be frequently examined for bent rods and loose joints4 ,a bend in the drag link or steering knuckles will throw the front wheels out of true1 in which case the tires will be badly worn4 ,when going straight ahead1 the wheels should be parallel2 if this is the case1 the angles of the steering arms will give the proper track when making a turn4 ,,care ,,of ,,springs ,the springs of an automobile are in constant motion1 and should be as carefully lubricated as the other parts of a car4 ,the spring hangers by which the two halves of a full elliptic spring are joined1 or by which a half elliptic spring is attached to the frame1 are often provided with grease cups1 but in the absence of these the parts should be frequently oiled4 ,once a season fresh lubricant should be applied to them4 ,the leaves of a spring may usually be separated enough for this by jacking up the body1 applying the jack to the frame2 the springs will thus be relieved of the weight1 and the leaves will separate sufficiently to permit heavy grease or graphite to be introduced between them by means of a table knife4 ,if the springs are too heavy to permit this1 they must be taken apart1 which may be done by removing them from the car and releasing the clips by which they are held together4 ,in reassembling a spring1 it may be clamped in a vise1 when the clip may easily be secured4 ,,adjusting ,,vibrators ,in adjusting the vibrators1 the best guide is the running of the engine4 ,the musical tone that they make is misleading1 for a difference in the steel of which the blades are made1 or in the quality of the core1 will produce a difference in the tone1 and because two vibrators sound alike is not proof that they are producing equal secondary sparks4 ,with a one-cylinder engine1 the adjusting screw may be turned until the engine is running at its best1 while at the same time there is the smallest spark between the vibrator contacts4 ,the adjustment of the vibrators of a multicylinder engine is proceeded with along similar lines1 all of the blades but one being held down1 while the free blade is adjusted until the best results are obtained in the operation of the cylinder to which it corresponds1 and the smallness of the spark between the vibrator contacts4 ,when one is correct1 it is held down and another released1 this process being continued until all are adjusted4 ,,matching ,,coils ,when coil boxes are so built that the units may be removed conveniently1 as is usually the case1 it often happens that the running of an engine may be improved by matching the coils and cylinders4 ,a difference in the compression in one cylinder will often cause it to run better on one coil than on another1 for no two coils will give identical results4 ,taking each cylinder in turn1 and transposing the coil units in the box1 the effect of each coil may be noted1 and a combination found that will improve the operation of the engine4 ,,adjusting ,,the ,,carburetor ,when adjusting a carburetor1 it must be remembered that the proportion of liquid gasoline to air in a correct mixture is very small2 because this is not well understood1 a rich mixture is present far more commonly than a poor one4 ,to begin at the beginning1 close both the gasoline and auxiliary air inlets1 and opening the gasoline adjustment a very little at a time1 crank the engine with the relief cocks open until combustion is secured1 the spark being retarded and the throttle nearly closed4 ,when the engine runs1 note the color of the flame that shoots out of the relief cocks4 ,a poor mixture will produce a yellow flame1 and a rich mixture a red and smoky flame1 with black smoke at the exhaust and a smell of gasoline4 ,the flame of a correct mixture is blue and hardly visible4 ,on securing a correct mixture at low speed1 advance the spark and open the throttle to speed up the engine1 and the mixture will at once become too rich4 ,adjusting the auxiliary air inlet by weakening the tension of its spring will bring the mixture to approximately correct proportions4 ,a more careful adjustment under road conditions can be obtained by adjusting the air inlet while the car is being operated1 for the position of the carburetor is usually such that this may be done while standing or kneeling on the running board4 ,faulty adjustment of the carburetor is often suspected when the real source is in the throttle or governor connections4 ,the bending of a rod connecting the throttle with either the foot1 hand1 or governor control1 or the wear of the joints1 will throw the carburetor out1 and the possible failure of these parts must be borne in mind accordingly4 ,,setting ,,the ,,valves ,in setting or timing the valves of a gasoline engine1 the point to be considered is the closing of the exhaust valve1 for upon this good results depend4 ,if this valve is held open too long1 the burned gases driven out will be drawn back into the cylinder1 and if it closes too soon the greatest possible quantity of burned gases will not have been expelled4 ,the many experiments carried on by the manufacturers1 and the attention that they must pay to this point1 result in the delivery of cars with valves correctly timed1 and usually with marks made on the two-to-one gears to guide in resetting them4 ,in the absence of these guides1 the setting of valves need not be difficult1 although experimenting is required to secure the best results4 ,the first step is to locate the position of the piston in the cylinder4 ,there is always an opening in the cylinder head--a relief valve1 the spark-plug opening1 or other--and a stiff wire may be dropped through it1 with its lower end resting on the piston and its upper end projecting4 ,as the piston is moved by cranking the engine1 the wire will move with it1 and is to be marked with a file at its highest and lowest positions4 ,while no fixed rule can be laid down1 it may be said that in general the exhaust valve should close when the piston has made from #a_/fd to #a_/cb inch of its outward stroke4 ,the two-to-one gears having been unmeshed1 the cam shaft may be revolved in its bearings by hand2 cranking slowly1 move the piston down from its highest point to that at which the exhaust should close1 and hold it there4 ,revolve the cam shaft until the nose of the cam is passing from under the roller of the valve-lifter rod1 and the valve just closed4 ,this point may be accurately ascertained by placing a strip of thin paper between the valve-lifter rod and valve stem2 when the cam is acting on the valve-lifter rod1 the paper will be pinched1 but the seating of the valve will release it4 ,when the paper can be pulled out1 mesh the two-to-one gears1 and the relations thus established between the crank and the cam shafts will be maintained4 ,cranking the engine a few times1 using the strip of paper1 will verify results1 and the engine may then be started and the effect noted4 ,if the running is not satisfactory1 unmesh the gears1 and mesh them with a difference of one tooth1 first one way and then the other1 noting results1 and retaining the most satisfactory position4 ,cams are often cut in one piece with the cam shaft1 and the gear keyed on the end2 there is therefore no chance to make a finer adjustment than what is permitted by shifting the gears one tooth at a time4 ,on multicylinder engines1 one cam shaft operates all of the exhaust valves1 and the setting of one valve sets all4 ,when inlet valves are of the mechanically operated type1 but controlled by a separate cam shaft1 this must be set in a similar manner4 ,the nose of the cam should just be coming into contact with the push rod roller at the instant when the exhaust valve is completely closed4 ,this should occur as the piston begins to move outward on the inlet stroke1 the exact position being determined by experiment4 ,when the cams are so badly worn that if they are set to open correctly they close too soon1 the best remedy is a set of new cams2 for while the brazing of a strip of brass to the sides of the cams can be resorted to1 the result is only temporary at best1 and not as accurate as that secured by the use of new cams4 ,while the tension of the spring of an automatic valve is sometimes controlled by a nut1 its adjustment usually depends on the stretching of the spring to strengthen it1 or the cutting off of part of a turn to weaken it4 ,the tension should be adjusted1 one cylinder at a time1 until the best results from each are secured4 ,,the ,,wiring ,illustration3 ,,fig4 #ej4--;,,jump ,,spark ,,wiring ,,diagrams4 ,in laying the wires for the ignition system1 only the best wire should be used1 and all contacts should be bright and clean4 ,connections should be tight1 and covered with vaseline to prevent corrosion1 additional protection being secured by binding all exposed places with so-called electric tape4 ,there should be the fullest protection against chafing and moisture1 and no sagging of the wires4 ,beginning with the battery1 the cells should be placed in a box that holds them securely1 so that there may be no jolting1 for this in working the wires will tend to loosen the connections4 ,in connecting the cells1 the wires should be cut to correct length1 but not so short that they will be drawn tight when connected4 ,the insulation should be cut off cleanly1 and the paraffin that will cling to the metal scraped off4 ,the ground wire may then be run1 after which the wires from the two batteries may be connected to the switch4 7,fig4 #ej74 ,on multicylinder engines1 one circuit should be completed and tested before another is started1 as this obviates the danger of confusing the wires4 ,the primary wire should be run from a coil unit to its timer contact1 making sure by the buzzing of the vibrator that the current flows when the switch is closed4 ,a buzz of the vibrator when the timer is not making contact indicates a short circuit4 ,the primary circuit for the coil having been correctly arranged1 the secondary connection should be made and tested before laying the primary of the next coil unit4 ,in making the timer contacts of a four-cylinder engine the firing order as established by the opening of the exhaust valves must be kept in mind4 ,with the spark control lever in the retarded position1 the timer should be set so that it is just beginning to make a contact when the piston in cylinder ,no4 #a is at top dead center of the compression stroke4 ,this contact should then be connected to the primary terminal of the first coil1 and the secondary of that coil connected to the spark plug4 ,if the firing order is #a1 #b1 #d1 #c1 7,fig4 #ea71 cylinder ,no4 #b will be the next to fire1 and the primary of coil #b should be connected to the next timer contact in the direction of rotation4 ,as the next cylinder to fire will be ,no4 #d1 the timer contact that will next be reached should be connected to coil ,no4 #d1 the remaining contact point being connected to coil ,no4 #b4 ,in the diagram the timer is supposed to be moving in the same direction as the hands of a watch4 ,illustration3 ,,fig4 #ea4--;,,jump ,,spark ,,wiring ,,diagrams4 ,there is no difference in the wiring of a horizontal double-opposed and a two-cylinder vertical #ahj crank-shaft engine1 as shown in ,fig4 #ej1 except that the timers are so built that in the first the two contacts are a quarter revolution apart1 and in the second a half revolution4 ,in wiring a car with a single coil and secondary distributer the four contacts of the timer all lead to the primary terminal of the coil1 the firing order being according to the manner in which the secondary terminals of the distributer are connected to the cylinders 7,fig4 #ea74 ,wiring for the make-and-break system is much simpler than that of the jump-spark1 and when a magneto alone is used1 it consists1 as will be seen from ,fig4 #eb1 of only a wire from the magneto to the igniters1 the other terminal of the magneto being attached to its metal base in such a manner that the ground connection is made when the magneto is secured in position on the engine4 ,the firing order is according to the setting of the cams that operate the igniter tappets4 ,illustration3 ,,fig4 #eb4--,,make-,,and-,,break ,,wiring ,,diagram4 ,magneto and coil4 ,battery for starting4 ,illustration3 ,,fig4 #ec4--,,make-,,and-,,break ,,wiring ,,diagram4 ,magneto ignition without coil4 ,starting on magneto4 ,,lubrication ,,table4 ,,part4 ,,lubricant4 ,,quantity4 ---------------------------------------- ---------------------------------------- ---------------------------------------- ------------------ ,engine cylinder ,cylinder oil #f-ab drops per minute4 ,engine bearings ,cylinder oil #h drops per minute4 ,require ,fan bearings ,cylinder oil #a drop every #b constant minutes4 attention4 ,magneto1 plain bearing ,cylinder oil ,keep pockets full4 ,wash out with kerosene once a season4 ,clutch leather 7,vegetable71 ,if clutch castor oil1 slips or neatsfoot oil leather gets hard1 keep off machine oil4 ---------------------------------------- ---------------------------------------- ---------------------------------------- ------------------ ,valve lifters ,cylinder oil ,with oil-can4 ,timer-shaft ,cylinder oil ,with oil-can4 ,pump shaft drive ,cylinder oil ,with oil-can4 ,magneto drive ,cylinder oil ,with oil-can4 ,lubricator shaft ,cylinder oil ,with oil-can4 ,require ,clutch release ,cylinder oil ,with oil-can4 attention ,lever bearing ,cylinder oil ,with oil-can4 daily4 ,steering knuckle ,grease ,one turn4 ,water pump ,grease ,one turn4 ,clutch-shifting collar ,grease ,one turn4 ,transmission bearings ,grease ,two turns4 ,outer bearing live ,grease or oil ,two turns4 rear axle ---------------------------------------- ---------------------------------------- ---------------------------------------- ------------------ ,starting-crank bracket ,cylinder oil ,few drops4 ,spring shackles ,cylinder oil ,few drops4 ,make and break tappets ,cylinder oil ,few drops4 ,pedal-shaft brackets ,cylinder oil ,few drops4 ,speed-change lever ,cylinder oil ,few drops4 ,emergency lever ,cylinder oil ,few drops4 ,require ,brake supports ,cylinder oil ,few drops4 attention ,brake equalizers ,cylinder oil ,few drops4 weekly4 ,control levers and ,cylinder oil ,few drops4 joints ,spring hangers ,cylinder oil ,few drops4 ,clutch2 multiple disk1 ,spindle oil and steel on steel kerosene1 or kerosene and little graphite ,clutch2 multiple disk1 ,no oil1 little leather on steel graphite ,internal expanding ,thin oil clutch ,,part4 ,,lubricant4 ,,quantity4 ,engine crank case4 ,cylinder oil4 ,steering gear case4 ,grease4 #c turns or gunful4 ,transmission-case1 ,gear case sliding compound or heavy gear system4 oils1 or either ,require mixed with about attention ten per cent4 of every two graphite4 ,let gears dip4 weeks or ,transmission case1 ,light motor oil and every #cjj individual little graphite4 miles4 clutch type4 ,planetary ,non-fluid oil1 or ,fill up no transmissions4 oil and graphite4 higher than shaft bearing4 ,live rear axle ,non-fluid oil or heavy steam engine housing4 cylinder oil2 grease and oil4 ,one quart4 ---------------------------------------- ---------------------------------------- ---------------------------------------- ------------------ ,magneto1 ball bearing4 ,cylinder oil4 ,small amount4 ,front and rear wheel-hubs2 ball or roller bearing4 ,grease4 ,require ,front and rear attention wheel-hubs2 monthly plain bearing4 ,graphite and oil4 or every ,leather boots of #ejj miles4 steer-rod joints and steer drag-rod joints4 ,grease4 ,universal joints4 ,grease4 ,remove covering1 inspect and repack4 ,torsion and distance rods4 ,oil4 ,timing gears4 ,non-fluid oil2 graphite if exposed4 ---------------------------------------- ---------------------------------------- ---------------------------------------- ------------------ ,friction disk ,keep oil off transmission4 friction surfaces1 ,renew friction ,require wash off with compost every attention gasoline1 dress #a1jjj miles4 at greater with belt dressing periods4 or ,french chalk4 ,chains4 ,chain graphite4 ,twice a year boil in graphite and grease after washing well in kerosene4 ,,appendix ,,operation ,,and ,,care ,,of ,,low ,,and ,,high ,,tension ,,magnetos ,,and ,,magneto ,,ignition ,,systems ,,general ,,principles ,the red-painted toy magnet that is one of the properties of childhood and with which everyone is familiar1 may well be used as the beginning of a study of the magneto1 for with it the characteristics of magnetism may be observed4 ,a little experimenting will show that the magnet will attract1 or 8pick up01 iron and steel objects only1 having no effect on copper1 brass1 lead1 wood1 or1 for practical purposes1 any other substance4 ,furthermore1 it illustrates the fact that when iron and steel are in contact with it1 they in turn become magnetic1 able also to attract tacks and other bits of the same metals4 ,iron1 however1 is shown by experiment to be magnetic only when in actual contact with the magnet1 losing its magnetism as soon as the contact is broken1 while when steel is magnetized by touching it to a magnet it remains magnetic4 ,this fact is illustrated by the magnet itself1 which is of steel and therefore capable of retaining its power for a greater or less time1 depending on its quality and hardness4 ,illustration3 ,,fig4 #a4 ,,magnetic ,,lines ,,of ,,force4 ,if iron filings are scattered on a piece of paper laid over a magnet they will not fall evenly and regularly1 but will collect most thickly at the ends1 or poles1 of the magnet1 showing that there the magnetic attraction is stronger than at any other points4 ,if the filings are examined closely it will be seen that they have taken up definite positions1 forming lines and curves extending between the two poles 7,fig4 #a74 ,this is the simplest method by which the magnetism may be made visible1 and it illustrates the fact that the power of a magnet acts in a series of lines passing from one pole to the other4 ,if a piece of iron or steel is placed across the poles of a magnet these lines1 or as many of them as possible1 will use it as a bridge or conductor1 because they can pass through it more easily than through air4 ,such a piece of iron or steel is called a keeper1 and by its use the magnet will retain its strength for a much greater time than if the lines are obliged to make their way through the far greater resistance that the air presents to their passage4 ,these lines1 which are known as magnetic lines of force1 always move in the same direction1 passing through the air or the keeper from the north pole of the magnet to the south pole1 and passing through the metal of the magnet itself from the south pole to the north pole4 ,the strength of a magnet depends on the number of these lines of magnetic force that it possesses4 ,if two magnets1 one strong and the other weak1 are placed under sheets of paper on which iron filings are scattered1 their comparative strengths are clearly shown by the difference in the number of lines of force that the filings show them to possess4 ,the space through which a magnet makes itself felt is known as the magnetic field1 and this is large or small1 according to the number of lines of force4 ,the stronger the magnet1 the larger will be the sweep of the curves of its lines of force1 and the greater will be the field that they form4 ,when a piece of iron or steel is placed in contact with a magnet1 the lines of force flow into it1 and it becomes magnetized1 throwing out lines of force and forming its own magnetic field1 which is quite distinct from the magnetic field of the original magnet4 ,if the piece is of iron1 its lines of force and its field die away as soon as it is separated from the magnet1 but a piece of steel once magnetized will retain its magnetism and1 of course1 its lines of force4 ,a wire of nonmagnetic metal1 such as copper1 for instance1 will not have the slightest attraction for iron filings1 but when an electric current is passed through it the filings will act as if the copper were a magnet1 clinging to it as long as the current passes1 and dropping as soon as the circuit is broken4 ,as a matter of fact1 an electric current sets up lines of magnetic force exactly similar to those of a permanent magnet1 their number being in proportion to the strength of the current4 ,as has been stated1 iron becomes magnetized when magnetic lines of force flow into it4 ,if1 therefore1 a wire through which an electric current passes is wound around an iron rod1 the lines of force set up by the current will pass into the rod and magnetize it1 so that it sets up its own magnetic field4 ,this magnetic field is created when the electric current starts flowing in the wire and dies out when the flow of the current is stopped1 for then the lines of force due to the current die out1 and the iron1 which depends on them for its magnetism and which has not the ability to retain its lines of force1 returns to its original nonmagnetic condition4 ,an arrangement of this sort1 consisting of a soft iron core1 around which is wound a number of layers of insulated wire1 forms an electro-magnet1 and will produce a magnetic field whenever an electric current passes through the wire4 ,the action is practically instantaneous1 the magnetic field appearing and dying out on the making and breaking of the electric circuit4 ,a magnetic field may thus be produced by the action of an electric current1 and an electric current in turn may be produced by the action of a magnetic field4 ,to generate a current by this method it is only necessary to place a conductor forming a closed circuit in a magnetic field1 and to change the strength of the field1 making it stronger or weaker4 ,for an example1 a length of insulated wire may be wound on an iron bar1 and the bar then touched with a magnet4 ,as soon as the lines of force flow into the bar it becomes magnetized and sets up a magnetic field in which the lines of force follow the law and flow from one pole to the other through the air4 ,the formation of this field is exceedingly rapid1 but during the time that the field is forming and increasing to its full strength1 an electric current will flow in the wire winding4 ,when the field has reached its full strength1 the flow of the current ceases4 ,on separating the bar from the magnet it loses its magnetism1 and the field set up by it dies away2 or in other words1 its strength undergoes another change1 now growing weaker as the bar returns to a nonmagnetic condition4 ,this dying out of the field generates another momentary flow of current in the wire1 which moves in the direction opposite to the flow of the current generated while the strength of the field was increasing4 ,the current generated is called an induced current1 and the method of producing it is called induction4 ,the intensity of the induced current in any given winding depends on the extent of the change in the strength of the field and upon the rapidity with which it occurs4 ,a bar of iron is limited as to the strength to which it can be magnetized2 or in other words1 it can only set up a limited number of lines of force4 ,increasing the strength of the field from nothing to this point1 or reducing its strength from this point to nothing1 gives the greatest change in strength possible to obtain1 and if this change occurs in the shortest possible time1 then the current induced will be of the greatest intensity that can be obtained from a conductor of the size and length used4 ,for an understanding of the action of a magneto it is necessary to bear in mind the following points3 ,first4 ,that a magnetic field is composed of lines of magnetic force that flow from one pole of the magnet to the other4 ,second4 ,that the lines of force will take the path that presents the least resistance4 ,third4 ,that an electric current will be generated1 or induced1 in a conductor placed in a magnetic field whenever the strength of the field changes4 ,fourth4 ,that the current flows only while the change in strength is taking place1 ceasing to exist when the field becomes uniformly strong or weak4 ,to make a practical application of the laws governing the production of an induced current1 a conductor forming a closed circuit is placed in a magnetic field1 and the strength of the field caused to change1 alternately becoming strong and weak4 ,in magnetos1 the magnetic field is due to two or more powerful steel magnets1 and the conductor1 a length of insulated copper wire1 is wound on a soft iron core and revolved between the poles of the magnets where the field is strongest4 ,the magnets are known as the field of the magneto1 and the wire on its core the armature4 ,the shape of the iron armature core is shown in ,fig4 #b1 the winding being indicated by heavy black lines4 ,on the inside of the poles of the field are pole pieces1 which are blocks of soft iron hollowed out to receive the armature4 ,as the successful operation of the magneto requires the lines of force to have as easy a path as possible1 the air space between the armature heads and pole pieces is very small1 being in the neighborhood of #a_/ajj of an inch4 ,illustration3 ,,fig4 #b4--;,,armature4 ,illustration3 ,,fig4 #c4 ,when the armature is not in position1 the lines of force will be required to pass from one pole piece to the other through the air1 and as they will seek the path of lowest resistance1 most of them will pass between the lower points of the pole pieces1 where the air gap is short1 and where the lines of force are present in the greatest number 7,fig4 #c74 ,when the armature is placed between the pole pieces1 however1 it gives the lines of force a path of still lower resistance1 and they will therefore follow it1 whatever its position may be4 ,if the armature is free to turn1 it will take a horizontal position1 as shown in ,fig4 #d1 for then the heads are entirely in contact with the pole pieces1 and the greatest possible number of lines of force can take the path offered by the neck of the armature4 ,illustration3 ,,fig4 #d4 ,illustration3 ,,fig4 #e4 ,when the armature is in this position1 the neck is magnetized by the flow of lines of force through it and sets up a powerful magnetic field which is quite distinct from the field thrown out by the field magnets4 ,if the armature is revolved1 it takes the lines of force1 or most of them1 with it1 and they continue to flow through the neck as long as one head of the armature is in contact with the north pole piece and the other head in contact with the south pole piece1 for even this long and distorted path1 as shown in ,fig4 #e1 is of less resistance than the air gap4 ,the lines of force1 however1 resist this lengthening of their path1 and tend to hold the armature with the neck horizontal1 when their passage is easiest4 ,if the armature is turned by hand1 it will be noticed that it becomes harder to turn as the neck approaches the vertical position1 and if the magnets are sufficiently powerful1 a great effort will be necessary4 ,once vertical1 however1 the armature hangs1 and a still greater effort is required to continue the revolution1 for the lines of force have found new paths of low resistance 7,fig4 #f74 ,each armature head now forms a bridge between the pole pieces1 and the lines of force divide1 some going through the upper head and some through the lower4 ,the lines entirely abandon the neck1 and in consequence its magnetic field dies out4 ,when these paths are broken by continuing the revolution of the armature1 the lines of force again flow through the neck1 and its magnetic field is again established 7,fig4 #g74 ,this action occurs twice during each complete revolution of the armature1 and if the armature is revolved by hand1 the two points when the neck is horizontal and the movement easy will be very distinct from the hard points when the neck is going over the vertical position4 ,illustration3 ,,fig4 #f4 ,illustration3 ,,fig4 #g4 ,in one revolution the neck is twice magnetized and demagnetized2 or in other words1 the magnetic field set up by the neck as the lines of force pass through it twice changes its strength1 being strong when the neck is horizontal and weak when it is vertical4 ,the winding on the armature is affected by this magnetic field1 and electric currents are induced in it by these changes in its strength4 ,the greatest change in the strength of the field occurs as the armature moves into the vertical position1 when its heads form bridges between the two pole pieces 7,fig4 #f74 ,up to this point the armature neck is strongly magnetized1 but its magnetic field dies out as the neck becomes vertical4 ,it is at this point then that the induced current is at its greatest intensity and becomes sufficient for ignition purposes4 ,in making an armature the channels are wound full of wire1 and this is retained against the action of centrifugal force by two or three short lengths of wire bound around the armature and lying in grooves cut in the heads for that purpose4 ,disks of brass are also screwed to the ends of the armature core1 and assist in making it dust and water proof4 ,the magneto must have a base1 and this must be of some nonmagnetic metal1 like brass1 for if it were made of iron it would provide a convenient path for the lines of force1 and they would have no interest in passing through the armature4 ,there must also be bearings for the armature shaft1 and these are either plain or ball1 set in brass plates screwed to the ends of the pole pieces4 ,a zinc or aluminum plate covers the space over the armature and between the upper edges of the pole pieces1 so that the armature revolves in a tunnel that is proof against the entrance of dust and water4 ,there are1 of course1 two ends to the wire wound on the armature1 but the simplicity of a magneto is increased by grounding one end on the metal of the armature1 the other end being brought to the single terminal 7,fig4 #b74 ,the circuit is therefore complete when this terminal is connected to any metal part of the magneto2 or1 as the magneto is mounted directly on the metal of the engine1 to any metal part of the engine or frame of the car4 ,the live end of the armature winding is brought out by means of a metal rod passing lengthways through the shaft of the armature1 the rod being insulated from the shaft by means of a hard rubber bushing or tube4 ,the terminal of the winding is therefore found at one end of the armature shaft1 and the current flows from this revolving part to the stationary binding post by means of a carbon or steel spring that is kept pressed against the end of this rod4 ,magnetos are classified as ,l4 ,t4 7low tension7 and ,h4 ,t4 7high tension7 according to the current that they deliver1 the word tension being used to indicate the pressure or voltage of the current1 but more accurate expressions would be primary and secondary magnetos4 ,the magneto already described is of the low-tension type1 and is used for the make-and-break ignition system1 its winding being so proportioned that at maximum speed it delivers a current of from #ajj to #aej volts4 ,what is often spoken of as a high-tension magneto is employed for the jump spark system1 a magneto of the type described delivering a current that flows through the primary winding of a secondary induction coil2 but this use of the term is erroneous1 for while the system delivers a high-tension spark1 this is from the coil4 ,the magneto itself is not only of the low-tension type1 but its current must be so feeble that the danger of burning out the coil is obviated4 ,a true high-tension magneto has two windings on the armature2 one1 the primary1 consisting of a few layers of coarse wire1 over which the very great number of layers of fine wire forming the secondary is wound4 ,this may give a current of from #aj1jjj to #bj1jjj volts1 and is used for the jump spark ignition system4 ,these types and their applications will be discussed in the succeeding chapters4 ,,magnetos ,,in ,,general ,one of the great advantages resulting from the use of a magneto is that for ordinary running it does away with the necessity for the hand advance of the spark4 ,the greater the speed at which a magneto runs1 the more abrupt is the change in the strength of the magnetic field1 and in consequence the greater is the intensity of the current delivered4 ,when running at slow speed1 the spark produced in the cylinder will be weak and thin2 it will be sufficient to ignite the mixture1 but the ignition will occur slowly4 ,at high speeds1 on the contrary1 the intensity of the current produced will be such that a flame rather than a spark will be produced1 and ignition will occur much more rapidly and positively4 ,when starting an engine on the magneto1 the spark control lever must be advanced more than is necessary for ignition by battery1 and the engine must be cranked at such a speed that the magneto will produce a current sufficient for ignition4 ,once started1 it is rarely necessary to move the spark control lever1 except for high speeds1 for speeding the engine up by opening the throttle will increase the speed of the magneto1 and the flaming spark will result in a quicker ignition of the mixture4 ,because a magneto does not deliver a continuous current1 it cannot be driven by a belt or by friction1 for a slight slip would throw it out of time with the engine4 ,the best drive is by gears1 for this is positive1 and there is a minimum of lost motion4 ,in some cases the magneto is driven by chain and sprocket1 and while this prevents slipping1 there is considerable lost motion when the chain is loose enough to run smoothly1 and the magneto cannot be timed as accurately as is possible with gears4 ,,magneto ,,troubles ,if the ignition fails1 and the question arises as to the reason1 the condition of the magneto may be tested quickly and in a most satisfactory manner4 ,it either gives a current or it does not1 and to learn its condition it is only necessary to disconnect it from the ignition system1 and to connect one end of a length of wire to its terminal4 ,holding the free end of this wire in the bare fingers of one hand1 and cranking the engine with the other hand1 also bare1 a shock will be felt as the armature revolves1 if it is in good condition4 ,if this test is too strenuous1 the free end of the wire may be held lightly against the teeth of a gear while an assistant cranks the engine briskly4 ,as the wire falls from tooth to tooth1 a time will come when the point of maximum current coincides with the breaking of the circuit at the gear1 and if the magneto is in good condition1 a flaming spark will appear4 ,there is little about a magneto of the type described to get out of order4 ,oil or dirt between the spring or brush and the end of the conducting rod may prevent the flow of current1 or1 what is more unlikely1 the wire of the armature may be broken4 ,the last trouble is of rare occurrence1 for when winding the wire on the armature it is shellacked1 and for all practical purposes the whole becomes a solid mass4 ,the only point where the wire can break is the half-inch of it that is connected to the inside end of the conducting rod that passes through the shaft1 and the condition of this may be learned by removing the dust cover and looking4 ,if broken1 a drop of solder1 carefully applied1 will repair the damage4 ,a question that is frequently asked is regarding the liability of the field magnets to lose their magnetism4 ,if made of the proper material1 and handled and used under proper conditions1 they should hold their magnetism indefinitely4 ,the strength of a toy magnet may be increased by tearing its keeper sharply away from the poles1 and as sharply replacing it1 the operation being repeated4 ,when the armature of a magneto revolves1 it performs the same office for the field magnets1 and it has the effect of keeping them up to strength indefinitely4 ,if the magneto is mishandled1 however1 it is another story1 and an inquisitive or careless worker can almost instantly weaken a field by removing the armature without taking the proper precautions4 ,the armature1 when in position1 acts as a keeper1 and provides a path of low resistance for the passage of the lines of magnetic force4 ,if the keeper is taken away1 the lines of force are required to traverse the higher resistance of the air1 and many of them then being overcome1 their number decreases and the field becomes greatly weakened4 ,this takes place instantly on the removal of the armature4 ,it is rarely necessary for a chauffeur to remove the armature of a magneto1 but when it is required1 the first step is the placing of a heavy plate of iron under the arch of the magnets1 and in close metallic contact with the pole pieces1 the dust plate being removed4 ,this will act as a keeper1 and the armature may then be removed4 ,if such a plate of iron is not at hand1 both of the end plates may be unscrewed and one of them removed1 and then1 as the armature is drawn out slowly1 small steel tools1 or short lengths of iron rod1 well cleaned1 may be fed in after it1 so that the cavity is well filled4 ,if these precautions are taken the armature may be removed with safety1 but it is better not to attempt this1 and it is never advisable to detach the magnets from the base or pole pieces4 ,so much damage may be done to a magneto by an unskilled man1 that some of the manufacturers go to the length of equipping their magnetos with seals1 the breaking of which is evidence that the machine has been tampered with1 and that someone is directly to blame if it does not deliver current4 ,when an engine is equipped with a double system of ignition1 or when there are two sources of current1 one being a magneto1 the greatest care must be taken to prevent even the momentary flow of the battery current through the armature winding1 for this will result in the demagnetization of the field4 ,the same trouble will result if the magneto current is led through the winding of a primary induction coil in the hope of intensifying the current4 ,should the battery current flow through the armature winding1 the core would be magnetized1 for it would then be an electro-magnet1 and the magnetic field set up by the armature under such conditions would overcome the less powerful field set up by the field magnets and their strength would instantly be reduced4 ,it is very essential to keep the armature bearings thoroughly lubricated in order that there may be as little wear as possible4 ,the clearance between the armature heads and the pole pieces is so slight that a trifling amount of wear in the bearings would permit the two to rub or strike4 ,the best magnetos are equipped with ball bearings1 provided with wick feeds that keep them lubricated1 but even with these the lubrication must be watched4 ,oil cups are provided1 which must be kept filled1 but it must be remembered that an excess of oil may make trouble in working its way into the armature winding and destroying the insulation4 ,in some cases the oil cups are provided with an overflow1 which prevents excessive oiling and the collection of surplus oil around the bearings4 ,,low-,,tension ,,ignition ,,system ,in utilizing the current of a magneto for ignition purposes1 the circuit is so arranged that it is first closed and then opened1 the closing of the circuit permitting the current to flow1 and the breaking of the circuit resulting in a spark at the break4 ,the closing and opening of the circuit is due to the action of the igniter1 which is a device located in the cylinder wall1 one end projecting into the combustion space and the outside end bearing the parts by which it is operated4 ,the two chief parts of an igniter are the stationary and movable electrodes1 so arranged and connected that when the movable electrode comes into contact with the stationary electrode the circuit is closed1 and when it moves out of contact the circuit is broken4 ,the stationary electrode is a steel pin or screw passing through the cylinder wall1 and carefully insulated from it by a tube or bushing of mica or other insulant that is proof against the heat and pressure produced in the combustion space4 ,the current developed by the magneto is led to this stationary electrode4 ,the movable electrode rocks in a bearing in the cylinder wall1 the inside end of its short shaft carrying a finger that touches or separates from the stationary electrode as the shaft is rocked4 ,the outer end of the short shaft carries one or two short arms by which the shaft is moved4 ,the operation of the igniter is due to the action of a cam on the half-time shaft1 which moves a tappet rod that in turn acts on the arm controlling the movable electrode4 ,when the cam is not acting on the tappet1 the movable electrode is held out of contact with the stationary electrode1 and there is consequently no circuit for the current4 ,as the tappet is moved by the revolution of the cam1 the movable electrode is freed and is brought into contact with the stationary electrode by the action of a light spring4 ,this closes the circuit1 and the current flows4 ,the further revolution of the cam separates the movable electrode from the stationary1 and the sudden breaking of the circuit results in the production of a spark between the two4 ,there is a great variety in the construction of igniters1 but the operation is the same in all4 ,once in its revolution the cam operates the movable arm of the igniter1 permitting it to touch the stationary electrode1 and this establishment of the circuit is followed by its rupture as the continued movement of the cam causes the tappet again to operate the movable electrode4 ,a better spark for ignition purposes is obtained when the movable electrode is moved out of contact with the stationary electrode sharply than when it is moved slowly1 and for this reason the parts are so arranged that the tappet strikes the movable electrode a blow instead of pushing or pressing it4 ,this construction is shown in ,fig4 #h4 ,when the cam is not acting on the tappet1 the head on the tappet holds the movable electrode away from the stationary1 against the action of a light spring4 ,as the cam lifts the tappet1 the tappet head releases the movable electrode1 and the light spring draws it upward and against the stationary electrode1 establishing the circuit4 ,when the tappet drops off the cam1 it is brought down sharply by the tappet spring1 and its head strikes the movable electrode a sharp blow that results in the sudden breaking of the circuit4 ,illustration3 ,,fig4 #h4--,,make-,,and-,,break ,,system4 ,in some types1 the movable electrode comes into contact with the end of the stationary electrode1 which is then a screw1 and the distance between them may be adjusted by screwing it in or out4 ,in other types1 contact is made with the side of the stationary electrode1 in which case the adjustment of the distance is provided for on the movable electrode4 ,this distance should be about one sixteenth of an inch1 for this is ample for the production of a satisfactory spark1 and a greater distance will result in the more rapid burning of the contact points4 ,in multicylinder engines1 the current from the live end of the armature winding is led to a bus-bar of conducting material that serves to distribute it to the igniters4 ,the stationary and insulated electrode of each igniter is connected to this bus-bar by a short length of wire that either leads through a switch of ordinary construction1 or is provided with a plug on its end that fits into a socket on the bus-bar and serves the purpose of a switch by which the igniters may be thrown out of circuit when it is desirable4 ,as the magneto is grounded when it is placed on the engine1 and as the movable electrode of the igniter is also grounded on the engine1 a circuit for the current is provided only when a movable electrode is in contact with a stationary electrode4 ,the construction of the cam shaft is such that only one igniter at a time makes contact1 which occurs during the compression stroke1 so that the rupturing of the circuit will occur at the point in the compression stroke when the spark is required for ignition4 ,to cut off the ignition circuit for the purpose of stopping the engine1 it would be bad practice to break the contact between the magneto and the bus-bar1 for while this would bring the desired result it might result in the injury of the magneto1 as there would then be no circuit for the current that the magneto would still be developing4 ,the best practice is to short-circuit the magneto1 and this is provided for by means of a simple switch1 one point of which is grounded1 and the other connected to any insulated part of the ignition system2 the magneto terminal1 bus-bar1 or other4 ,when this switch is closed1 a circuit is provided for the magneto current1 which1 in the arrangement shown in ,fig4 #h1 flows from the magneto to the bus-bar1 to the switch 7when closed71 to ground1 and back to the magneto4 ,if this circuit is provided1 the current will follow it1 abandoning the paths across the igniters as they operate1 and the production of sparks ceasing1 the engine will come to a stop4 ,,setting ,,up ,,the ,l4 ,t4 ,,system ,to obtain successful results1 the spark must be produced at the correct point in the compression stroke1 and this requires such adjustment of the igniters that the movable electrode breaks the circuit at this point4 ,because the magneto delivers a fluctuating current1 it is clear that the most satisfactory spark will be produced when it is so set that it will be delivering its maximum current at the instant that the igniters separate4 ,as most of the running of a car is done on an advanced spark1 the point of maximum advance must be determined in order to set or adjust a low-tension ignition system4 ,this point varies with different engines2 in a large proportion the piston has a 8lead0 of one half inch1 while in a smaller number the 8lead0 varies from this to three quarters of an inch4 ,by this it is meant that when advanced1 the spark occurs when the piston still has one half inch to travel to reach top dead center of the compression stroke1 or anything up to three quarters of an inch1 as the case may be4 ,inquiry of the manufacturers regarding this point will secure the information1 but if this is not possible1 the point may be found by experiment4 ,the first step is to bring one of the pistons to within one half inch of top dead center of the compression stroke4 ,this position may be determined by dropping a stiff wire through a compression relief cock or other opening in the cylinder head1 so that it rests on the piston and is moved by it4 ,the crank shaft of a four-cycle engine must make two revolutions to complete the cycle in one of the cylinders1 and during these two revolutions the piston will twice pass top dead center1 as will be shown by the movements of the wire4 ,it is necessary1 however1 to distinguish between top dead center of the compression stroke and top dead center of the exhaust stroke1 and this may be accomplished by watching the stem of the exhaust valve4 ,when the wire shows that the piston is moving toward top dead center1 and the exhaust valve stem shows the valve to be open1 the piston is known to be making the exhaust stroke1 and to get it to top dead center of the compression stroke it is necessary to continue the revolution of the crank shaft while the piston moves downward on the inlet stroke1 and again upward on the compression stroke4 ,during this second upward stroke the exhaust valve stem will not move1 showing the valve to be closed4 ,cranking must stop when the lack of movement of the wire shows the piston to be at top dead center1 and then the crank shaft must be turned backward by means of the flywheel until the piston has moved down one half inch4 ,this may be determined by making a mark on the wire and holding a rule firmly in such a position that as the wire follows the piston the mark will move along the graduations4 ,when the mark has moved down one half inch below top dead center1 the movement of the crank shaft must be stopped so that the piston is held in that position4 ,place the spark control lever in the advanced position1 when the nose of the cam should be just ceasing to act on the tappet4 ,the movable electrode must then be adjusted so that it is in the act of separating from the stationary electrode1 and this is performed by shortening or lengthening the tappet1 or otherwise setting the parts so that the tappet head is in contact with the outside arm of the movable electrode and beginning to move it away from the stationary electrode4 ,this point may be accurately determined by the use of an electric bell circuit4 ,connect a bell with three or four dry cells1 grounding the free terminal of the battery on the engine4 ,then breaking any connection between the igniter terminal and the ignition system1 connect the free terminal of the bell to the igniter4 ,the circuit will then consist of battery1 bell1 igniter1 and ground return1 and the bell will ring when the movable electrode is making contact with the stationary4 ,having adjusted the movable electrode so that it is approximately correct1 it may be tested by cranking the engine4 ,the bell should begin to ring during the compression stroke1 and should stop ringing when the marks of the wire show the piston to be one half inch from top dead center4 ,the igniter of each cylinder must be adjusted separately1 and when tests have shown them to be correct1 the lock nuts must be set up to hold them in position4 ,in attaching the magneto to the engine1 means must be provided for driving it at the proper speed4 ,in a four-cylinder engine1 two revolutions of the crank shaft are necessary for the production of a cycle in each of the cylinders1 two power strokes occurring in each revolution4 ,as the magneto delivers its maximum current twice in each revolution of the armature1 it must be driven at the speed of the crank shaft1 and as the drive is usually taken from the cam shaft1 the gear on the magneto must have half as many teeth as the gear on the half-time shaft with which it meshes4 ,to set the magneto1 the crank shaft should be revolved until one of the pistons 7it makes no difference which7 is in the firing position2 that is1 the position for which the igniter is set to open4 ,the armature should then be revolved by hand until it is just past the vertical position of ,fig4 #f1 with about one sixty-fourth of an inch of space showing between its rear edge and the edge of the pole piece from which it is moving4 ,this can most easily be accomplished by removing the dust cover and reaching under the arch of the field with the fingers4 ,holding the armature in this position1 its driving gear should be slipped into mesh with the gear on the half-time shaft4 ,in some makes of magnetos the gear is keyed to the armature shaft1 which determines its position in relation to the armature4 ,in this case1 the gears must be meshed as close to the indicated position as possible4 ,in other designs the magneto is driven by a positive clutch1 so that it is impossible to mesh it in any but the correct position4 ,in ,bosch magnetos there is no key1 but the shaft is tapered to fit a tapered hole in the gear1 so that a very exact setting of the magneto is possible4 ,when the gear is keyed to the armature shaft1 the closeness of the setting depends on the thickness of the teeth2 the thinner the teeth1 the closer it is possible to adjust the magneto4 ,if the armature gear has an uneven number of teeth1 however1 it is possible to make the setting by one half the thickness of a tooth4 ,if it is found that the thickness of the teeth is such that the armature cannot be set correctly1 give the armature and its gear a half turn1 when1 if the number of teeth is odd1 it will be found that a tooth on one side corresponds to the space between two teeth on the opposite side4 ,having set the magneto and drawn up the nut securing the gear to the armature shaft1 the system may be wired by running a wire from the terminal of the magneto to the bus-bar1 and other wires from the bus-bar to each of the igniter terminals4 ,the short circuiting switch should also be connected up1 the running of its wires depending on convenience4 ,the system installed1 it should be tested4 ,with the system adjusted as indicated1 the engine should start1 and a very short run will show if it is correct4 ,if it does not respond to advancing the spark1 or if its operation is not satisfactory1 a readjustment should be made1 giving the piston a lead of one eighth of an inch more1 or five eighths of an inch in all1 with the spark advanced4 ,if this shows an improvement1 but the engine still does not develop its full power1 the operation may be repeated1 the piston being given more lead by one sixteenth of an inch4 ,if the compression is not the same in all of the cylinders1 a closer adjustment of the igniters may be made that will improve the operation of the engine1 the tappet of the high compression cylinder being adjusted to operate the movable electrode slightly before the others1 so that the larger volume of mixture will have more time in which to burn4 ,the switches through which the igniters are connected to the bus-bar may now be brought into use1 and when three of them are open the engine should run on the single cylinder of which the circuit is complete4 ,testing the cylinders in this way1 running one at a time1 gives an opportunity for comparing their action1 and for noting those in which the power is weak4 ,if the weakness is due to ignition trouble1 it may be corrected by a further adjustment of the tappet4 ,,troubles ,failure of ignition due to magneto trouble has already been described4 ,any short circuit of the system will prevent ignition1 for the current will not flow across the igniters if another path is open to it4 ,short circuiting may be due to the chafing of the insulation of the wires1 to a frayed end of a stranded cable making contact with the metal of the engine1 to the carbonization or breaking of the insulation around a stationary electrode1 or to the sticking of a movable electrode in contact with a stationary4 ,operating the igniters by hand will show the presence of this last named condition1 and inspection of the insulation and terminals the presence of any defects4 ,loss of power is frequently due to the leakage of compression around the plate carrying the igniter1 around the stationary electrode1 or through the bearing in which the movable electrode rocks4 ,the side of the bearing toward the combustion space is built like a valve1 and when worn may be ground to a seat4 ,if the engine runs well at low speed1 but misses at high speed1 the fault may be located in faulty insulation of one of the stationary electrodes1 which holds the low-pressure current developed by the magneto at low speed1 but fails to retain the higher pressure developed when the speed is increased4 ,the faulty igniter may be located by running the engine one cylinder at a time4 ,the heat developed by the spark is very great1 and provisions must be made to preserve the contact points from undue corrosion4 ,these points are usually made of platinum1 or of an alloy of platinum and iridium1 and must be kept clean and smooth4 ,the spring that draws the movable electrode against the stationary must not be too strong or it will bring the contacts together with sufficient force to batter them out of shape4 ,this spring should be of sufficient strength to bring them together promptly1 but without undue force4 ,the tappet spring should be of considerable strength1 in order that the separation of the electrodes may be quick and positive4 ,after long running the contacts will become worn to such an extent that the spark occurs too late in the stroke to permit the engine to develop its full power4 ,this may be corrected by readjustment of the tappets1 so that ignition takes place earlier4 ,a wearing of the outside arm of the movable electrode1 or of the tappet head1 will have the same effect4 ,another cause of failure will be the weakness of the spring of the movable electrode1 which is so weakened that it will not do its work at high speed4 ,l4 ,t4 ,,magneto ,,with ,,secondary ,,coil ,the advantages of a magneto as a current producer for the low-tension system pointed the way to its adoption for the jump spark system also1 but it was at once recognized that it would be impossible to lead the current direct to the primary winding1 as the current from a battery is used4 ,the reason for this is that while the battery delivers a current of constant value1 the current obtained from a magneto is fluctuating1 its intensity depending on the positions of the armature as it revolves1 and the speed at which it is driven4 ,a current is induced in the secondary winding of the coil as the magnetic field set up by the core changes its strength1 and as has been explained1 the induced current is strongest when the greatest change in the strength of the field occurs in the shortest possible time4 ,the effect of the flow of the magneto current through the primary winding of the coil would be to magnetize and demagnetize the core slowly1 as the magneto current increased to its maximum and died away to the minimum1 and these gradual changes in the magnetic field of the core would induce currents in the secondary that would be too feeble to produce ignition of the charge4 ,when a battery is used with a coil1 the operation of the vibrator produces rapid magnetizations and demagnetizations of the core1 but as the field set up by the core dies away more rapidly than it is established1 the greatest current is induced by the breaking of the circuit4 ,in the best known method of applying a magneto to the operation of a secondary coil1 the magnetization of the core is caused to occur with exceeding rapidity1 and the current induced in the secondary winding as this occurs is sufficient for ignition4 ,this is known as the ,eisemann system1 and is in very general use4 ,a diagram illustrating the connections is shown in ,fig4 #i4 ,illustration3 ,,fig4 #i4--;,,eisemann ,,ignition ,,system4 ,the magneto is of the usual type1 but the winding is so proportioned that the current is of lower voltage than is delivered by what has been described as the low-tension type of magneto4 ,one end of the winding is grounded on the metal of the armature1 and the live end is carried to a contact screw4 ,the current flows to this screw1 and from there two paths are presented by which it may flow back and complete its circuit4 ,one of these paths leads through the primary winding of a secondary coil1 and the other through a lever that for the greater part of the revolution of the armature touches the contact screw4 ,the lever is grounded on the metal of the magneto1 and when it touches the contact the circuit that is then completed is short and of low resistance1 and the current follows it in preference to the circuit of higher resistance through the primary winding of the coil4 ,the flow of current is thus from the armature winding to the contact screw1 which is insulated from the metal of the magneto1 to the lever1 and by the ground back to the winding4 ,attached to the end of the armature shaft1 and so placed that it operates the lever1 is a cam with two projections1 these projections being arranged to move the lever away from the contact screw4 ,this arrangement is called the interruptor1 and by its operation it closes and opens the low-resistance circuit by which the magneto current may flow4 ,when the armature is horizontal1 and during the time that it is approaching the vertical1 the circuit is closed through the interruptor1 but when the armature reaches the position in which it gives its maximum current1 the interrupted is opened by the cam1 and the current1 losing its low-resistance circuit1 is required to flow through the primary winding of the coil1 for that is the only path by which it can return to the armature winding4 ,the sudden flow of this current through the primary winding results in the production of a powerful magnetic field around the core1 and this rapid growth in the strength of its field induces a current in the secondary winding that is sufficient for the ignition of the charge4 ,as the magneto current is at its maximum twice during each revolution of the armature1 the cam is arranged to open the low-resistance circuit at such periods that each maximum is required to flow through the primary of the coil4 ,in applying this system to a multicylinder engine1 it is necessary to distribute the secondary current to the different cylinders1 so that a spark will be produced in each as it is required4 ,this is accomplished by means of a secondary distributor1 consisting of a revolving conductor to which the secondary current is led1 and a stationary contact for each cylinder arranged in a circle1 to be touched as it revolves4 ,these stationary contacts are connected with the spark plugs1 according to the firing order of the engine4 ,during one revolution of the distributor1 a spark is produced in each of the cylinders1 and as two revolutions of the crank shaft are necessary in order to have power strokes occur in all of the cylinders1 the distributor must revolve at half the speed of the crank shaft4 ,the magneto produces a current that is sufficient for ignition twice during each revolution of the armature1 and therefore1 for four cylinder engines1 must run at the speed of the crank shaft4 ,for the sake of compactness1 the distributor is built into the magneto1 its shaft being carried in bearings that support it above the armature and under the arch of the field magnets4 ,it is geared to the armature so that the two revolve in a fixed relation to each other1 and in order that the distributor may run at half the speed of the armature1 its gear has twice the number of teeth of the gear on the armature shaft that drives it4 ,the secondary induction coil used is similar in construction to the coils used for ignition by battery1 except that it is heavier1 and has no vibrator4 ,the period during which the magneto is delivering its maximum current is so brief that there would hardly be time for a vibrator to get into action1 and even if this were not the case1 the making and breaking of the circuit by the vibrator is not necessary1 as the single change in the strength of the magnetic field set up by the core is so abrupt that the current induced by it is sufficient for the purpose4 ,the strength of this secondary current is such that it is necessary to provide a circuit for it if by any accident or oversight the circuit through the distributor or spark plugs is interrupted1 as would be the case should one of the secondary wires become disconnected4 ,this is taken care of by what is known as the safety spark gap1 which is a gap provided between the secondary terminals of the coil1 or between the live end of the secondary winding and the ground4 ,this safety spark gap1 in the case of the coil furnished by the ,eisemann company1 takes the form of two flat pieces of brass1 each in contact with one of the secondary terminals of the coil1 their pointed ends being separated by a distance of about half an inch4 ,when there is no interruption of the secondary circuit1 and the parts of the secondary system do not present undue resistance to the flow of the current1 the higher resistance of the air space between the points of the safety spark gap prevents the current from jumping between them1 but should one of the secondary cables become disconnected1 the pressure of the current will rise to a point that will enable it to jump the gap between the two points4 ,if it were not for this safety gap1 an interruption of the secondary circuit would make the pressure of the current rise to such an extent that there would be great danger of a spark passing inside of the coil1 rupturing the insulation4 ,as the magneto is received from the makers1 the parts will be in a fixed relation to each other2 when the armature is vertical1 and held in that position by the lines of force1 the cam is in the act of opening the primary interruptor1 and the revolving part of the secondary distributor has moved into contact with one of the stationary contacts about one thirty-second of an inch4 ,the interruptor of the magneto can be utilized as the timer for an ignition system by battery and coil1 the secondary current being distributed to the cylinders by the distributor4 ,a better arrangement1 however1 requires the use of two coils1 and a timer which is carried on the rear end of the distributor shaft4 ,the coil for the battery system is provided with a vibrator1 and connections are made in the manner usual with a system composed of these parts4 ,the coil is in a case that also contains the non-vibrator coil for the magneto system1 and the two wirings are separate and distinct with the exception of the secondary connection between the coil box and the revolving parts of the distributor1 which is common to both4 ,while little change in the position of the spark is required for this system1 provisions are made by which it may be advanced or retarded4 ,in one system1 the interruptor is operated by a groove in the face of the cam disk1 a pin on the end of the interruptor lever following the groove and being moved by the irregularities4 ,in this case1 the advance and retard of the spark is obtained by rotating a plate carrying the interruptor in one direction or the other1 so that the lever is moved earlier or later in the revolution of the cam4 ,in another type the gear driving the armature is not attached direct to the armature shaft1 but to a sleeve surrounding the shaft1 and the pulling out of a second sleeve between the two alters the position of the armature in relation to the driving gear1 resulting in the advancing or delaying of the moment when the maximum current is produced4 ,,setting ,,up ,,the ,,system ,in setting up a system of this description1 the firing order of the engine must be ascertained1 and this may be done by watching the order in which the exhaust valve stems move as the engine is slowly cranked4 ,piston ,no4 #a must then be brought to top dead center of the compression stroke1 and about one thirty-second of an inch down on the power stroke1 being stopped in this position4 ,with the magneto screwed into place1 the covers of the interruptor and distributor may be removed1 and the armature revolved by hand in the direction in which it will be driven1 until the interruptor opens1 the spark control being in the most retarded position4 ,a mark on the interruptor will come into line with a mark on the casing at the instant that the interruptor breaks contact4 ,the magneto gear should then be meshed with the gear that drives it1 and the lock nut set up4 ,the connection between the live end of the armature winding and the interruptor is arranged by the maker1 but it is necessary to make connections between the magneto and the coil4 ,a terminal will be found in the casing close to the stationary contact screw1 and this is to be connected with one of the primary terminals of the coil1 the other primary terminal either being grounded on the engine or the magneto1 according to the construction4 ,the moving part of the secondary distributor may then be connected with the secondary terminal of the coil4 ,if the coil has but three terminals1 two primary and one secondary1 there are no further coil connections to be made1 but if1 as is sometimes the case1 there are two secondary terminals1 the free one is to be grounded on the engine4 ,an inspection of the distributor will show that the revolving part is beginning to make contact with one of the stationary points1 and this point is to be connected to the spark plug of the cylinder in which the piston is at top dead center of the compression stroke4 ,the next distributor point in the direction of rotation is to be connected with the spark plug of the next cylinder to fire1 the remaining distributor points and spark plugs being connected in the order of firing4 ,magnetos of this type are built to run in either clockwise or counter clockwise1 and the two are not interchangeable4 ,the direction in which the magneto is to be driven is indicated by an arrow stamped on the gear casing or end plate4 ,when the system is properly installed1 the motor should start on a quarter-turn of the crank shaft1 the crank being given a quick upward jerk4 ,if it does not1 the setting is incorrect1 the connections are improperly made1 or there is too great a distance between the points of the spark plugs4 ,this distance should be one sixty-fourth of an inch4 ,,care ,the bearings of the armature and secondary shafts must be kept well lubricated1 as well as the parts of the interruptor that require it4 ,every few weeks1 depending on the use1 the carbon or steel brush bearing against the live end of the armature shaft must be wiped off with gasoline1 and the same care must be given to the distributor contacts and to the platinum contacts of the interruptor4 ,when the platinum contacts of the interruptor become worn down after long use1 or if for any other reason they require readjustment1 they must be set so that the distance between them at the moment that the cam holds them apart is not more than one one-hundredth of an inch4 ,this space may appear to be very small for the work that is to be performed1 but it will be sufficient1 and a greater distance will result in sparking that will burn down the contacts4 ,in the ,eisemann magneto1 the adjustable contact is held by two nuts1 and small open end wrenches are provided to fit4 ,a wrench should be applied to each of these nuts1 and the lower or lock nut loosened4 ,this will free the upper nut by which the adjustment may be made1 and the lock nut may then be tightened4 ,the contact faces of the platinums should be kept flat and smooth1 and true to each other1 so that they come together squarely4 ,if they are pitted after long use they may be faced off with a dead smooth file1 but this is a job that requires great care1 and must only be done under the most favorable conditions4 ,when completely worn down they should be replaced with new ones4 ,,troubles ,should the engine show a tendency to miss1 the first suspicion1 if the magneto contacts are known to be correct1 should fall on the spark plugs1 and the easiest method of testing them out is to replace them with new ones4 ,after considerable use1 the spark plug points will burn off1 and the size of the gap will increase to such an extent that the spark will find less resistance in traversing the safety spark gap than the gap in the plug4 ,in order that the ignition may be cut off for the purpose of stopping the engine1 a switch is always provided by which the magneto may be short circuited1 one pole of the switch being connected to the magneto terminal1 or live wire1 and the other pole grounded1 as shown in ,fig4 #i4 ,when this switch is closed1 the magneto current flows through it in a closed circuit1 and as it abandons its path through the interruptor there will be no further action in the coil1 the ignition of course ceasing4 ,this switch is often located in the rim or arm of the steering wheel1 so arranged that pressing on a button closes the circuit and diverts the magneto current from the coil4 ,any accidental short circuit of the magneto current will produce the same effect1 and in case of the abrupt cessation of ignition1 this is one of the probable causes4 ,a short circuit in the secondary will usually make itself known by the snapping of the sparks as they pass through broken insulation or from a frayed cable end4 ,the remarks on general magneto troubles and care already made on page #bed also apply to a magneto of this type1 and the same rules regarding the protecting of the circuit of the lines of the field must be borne in mind4 ,h4-,t4 ,,magneto ,,systems ,a high-tension magneto differs from the types described in that the armature has a double winding2 one1 the primary winding1 consisting of a few layers of coarse wire1 and the secondary winding1 placed over the primary1 consisting of many layers of very fine wire4 ,as the armature revolves1 a current is induced in the primary winding1 the circuit of which is kept closed until the armature reaches the position in which the induced current is at its greatest value4 ,an interruptor operated by a cam then opens the primary circuit1 and the sudden demagnetization of the armature core that results induces in the secondary winding a current of high pressure that is quite sufficient to jump the gap in the spark plug and to cause ignition of the mixture4 ,the construction of the armature is more delicate than is the case with a low-tension magneto1 for the secondary winding must have a large number of layers1 and to permit this in the limited space1 the wire must be fine4 ,in addition1 it must be insulated with the greatest care1 for the intensity of the current produced will enable it to seek out and to break down any weakness that exists4 ,there must also be two brushes1 one for the primary current and one for the secondary1 which complicates the construction4 ,illustration3 ,,fig4 #aj4--,,wiring ,,diagram1 ,h4-,t4 ,,magneto ,,interchangeable ,,with ,,secondary ,,coil4 ,a magneto of this type is shown in diagram in ,fig4 #aj4 ,in this case1 the inner ends of both the primary and secondary windings are grounded1 the live end of the primary being connected with the insulated contact of the interruptor1 and the live end of the secondary leading to the rotating part of a secondary distributor4 ,for the greater part of the revolution of the armature1 the cam on the armature shaft permits the interruptor to maintain a closed circuit1 but as the current reaches a maximum the cam breaks the circuit1 and the flow of the primary current ceases4 ,during this time1 the secondary circuit has been open1 the moving part of the distributor being out of contact with the stationary points4 ,under the law of induction1 a current will only be induced in a closed circuit1 and there is therefore no action in the secondary winding4 ,when the primary current is at its maximum and its circuit is broken1 another condition exists1 for then the secondary distributor is making contact1 the only gap being in the spark plug1 but the sudden demagnetization of the armature core as the primary circuit is broken1 and the additional effect as the armature passes the vertical position1 induces in the secondary winding a current of great intensity that passes to the spark plug by way of the distributor1 returning to the winding by the ground4 ,the parts of the interruptor are carried on one of the end plates of the magneto1 and the secondary distributor revolves in bearings that support it under the arch of the magnets4 ,in the diagram shown provisions are made for a double ignition system1 the operator having his choice of ignition by high-tension magneto direct or by battery1 timer and coil4 ,in practice1 the three switches shown operate together4 ,when magneto ignition is desired1 the switch between the battery and ground is opened1 and the switch at the secondary distributor thrown into contact with the point connected with the secondary terminal of the magneto4 ,the third switch is thrown to make contact between the primary terminal of the magneto and the interruptor4 ,if battery ignition is desired1 the switch on the magneto primary is thrown to the point through which it is grounded1 and the primary and secondary switches of the battery circuit closed4 ,the upper contact points of the interruptor are then utilized to close primary circuit of battery1 and the secondary current induced in coil is led to distributor4 ,this complication of switches is necessary to prevent possibility of the battery current flowing through the armature winding1 and to provide a short circuit for the primary of the magneto4 ,if the engine is running on magneto ignition1 it is stopped by throwing the primary switch to the point by which the primary is grounded4 ,if running on battery1 the circuit is broken in the usual way4 ,the current from a high-tension magneto is of such intensity that the small points of an ordinary spark plug would quickly be burned1 and it is necessary to provide plugs with heavy points1 which will stand the work4 ,the distance between the points should be about one sixty-fourth of an inch4 ,the ,bosch magnetos1 which are perhaps in more general use than any other1 are built on similar lines to the magneto just described1 except that the grounded end of the secondary winding1 instead of being attached to the metal of the armature1 is connected to the live end of the primary winding1 as shown in ,fig4 #aa4 ,the live end of the primary is brought out through a conducting rod passing lengthways through one end of the armature shaft1 from which the current flows to the stationary contact of the interruptor4 ,while in other magnetos the interruptor parts are stationary and operated by a moving cam1 in this type the interruptor parts revolve with the armature1 and the moving arm is operated by two fiber wheels as it drags around the inside of a stationary ring4 ,by rotating the ring and the two wheels the interruptor is caused to operate sooner or later in its revolution1 this giving the advance and retard of the spark4 ,illustration3 ,,fig4 #aa4--,,wiring ,,diagram1 ,,two-,,spark ,,magneto4 ,the other end of the armature shaft carries the collecting ring for the secondary current1 this consisting of a hard rubber disk around the surface of which is a metal ring to which the live end of the secondary winding is connected4 ,a carbon brush is kept pressed against this metal ring by a light spring1 and the current is thus led off to the revolving part of a secondary distributor4 ,the interruptor keeps the primary circuit closed until the current induced in the primary winding is at its maximum1 when the opening of this circuit causes the rapid demagnetization of the core1 and a powerful current is induced in the secondary1 which flows to the spark plug with which the distributor is making contact4 ,a safety spark gap is applied between the brass strip that conducts the secondary current from the collecting brush to the distributor1 and the metal of the magneto4 ,the necessity for this device has already been explained1 and it is essential that a magneto of this type should be so provided1 because of the intensity of the current4 ,,setting ,illustration3 ,,fig4 #ab4--,,timing ,,diagram1 ,,two-,,spark ,,magneto4 ,in setting up a system of ignition with a magneto of this type1 the firing order of the engine must be observed1 and then one of the pistons brought to the point in the compression stroke that it will occupy when the spark is at the greatest advance4 ,as has been explained in the case of engines equipped for the make and break system1 this point will usually be from one-half to three-quarters of an inch before top dead center1 the greater proportion of designs placing it at one-half an inch4 ,the driving gear of a ,bosch magneto is not keyed to the armature shaft1 but shaft and gear are tapered1 so that when the nut is drawn up tight there is no possibility of slipping4 ,after the magneto is secured in position its gear may be meshed with the gear that is to drive it1 but without drawing up the nut4 ,the armature may then be turned by hand until it is in the vertical position1 where it will be retained by the lines of force 7,fig4 #ab71 and the gear nut drawn up tight4 ,if this position of the armature cannot be obtained by the sense of touch1 it may be exposed to sight by the removal of the bridge that carries the safety spark gap1 and of the dust cover that protects the space between the upper sides of the pole pieces4 ,the loosening of the three-armed frame on the front of the magneto will permit the removal of the covers of the interruptor and timer1 and it will be seen that the moving part of the distributor is beginning to make contact with one of the stationary pieces2 this should be connected to the spark plug of the cylinder that is in the firing position4 ,the other contacts of the distributor should then be connected to the remaining spark plugs in the order of firing4 ,ignition is cut out by short-circuiting the primary winding1 and a binding post will be found on the front of the magneto under the three-pronged frame to which is connected the wire that leads to a switch making a ground connection when closed4 ,,care ,the armature and distributor shafts run on ball bearings1 and these require the application of a few drops of oil twice a month4 ,the interruptor is designed to operate without oil1 and there is therefore little danger of oil working its way into the winding4 ,the carbon brushes must be wiped off with a little gasoline occasionally1 and these are arranged in such a manner that they are easy of access4 ,the platinum contacts of the interruptor must be kept free from dirt and oil1 and when1 after long use1 they become worn and uneven1 they must be faced off by the use of a dead smooth file4 ,the distance between them when separated by the action of the fiber rollers must not be more than one sixty-fourth of an inch1 and this may be adjusted by means of the nuts4 ,accompanying each magneto is a small open end wrench for this purpose1 to which is pivoted a leaf of steel that is to be used as a gauge for this distance4 ,this same measurement applies to the spark plugs1 the points of which must provide a gap of not more than one sixty-fourth of an inch4 ,,troubles ,if there is an abrupt failure of ignition1 it is probable that the primary is short-circuited1 and this can only occur on the wire that leads to the short-circuiting switch1 for the other parts of the primary circuit are inclosed and protected against injury4 ,in case of the missing of one cylinder only1 the trouble will usually be found in the plug1 which may be short-circuited by a carbon deposit1 or because the intense heat of the spark has fused the metal1 resulting in the formation of a globule of metal between the spark points4 ,too great a distance between the points1 more than one sixty-fourth of an inch1 will prevent the passing of the spark1 which will then be seen in the safety spark gap4 ,a miss in different cylinders may be due to defective insulation of the wires1 but if these are in good condition the fault may be looked for in the magneto4 ,the place where trouble is usually experienced is in the interruptor1 which may become dirty1 or the contacts may be worn down or loosened from the vibration4 ,fouled contacts in the distributor may also lead to a miss-fire1 and this will be corrected by wiping the parts with gasoline4 ,if all of these parts have been examined and found correct1 it is inadvisable to examine further into the magneto1 for inexperienced handling will be likely to injure the delicate parts4 ,it is better to place it in the hands of a man whose shop is equipped for the work4 ,,four-,,spark ,,magneto ,all of the magnetos described have been of the type in which the armature revolves1 and two ignitions are secured per revolution4 ,these are known as two-spark magnetos1 or crank-shaft speed magnetos1 from the fact that for four cylinder engines the magneto runs at the speed of the crank shaft4 ,this is in distinction to the ,bosch four-spark1 or cam-shaft speed1 magnetos1 in which the armature as well as the field is stationary4 ,this magneto for its simplicity1 freedom from trouble1 and workmanship1 has few equals for the high-tension ignition of an internal combustion engine4 ,the armature in this magneto is of the usual type1 and is stationary1 with the armature neck in a vertical position4 ,around the armature1 and between it and the pole pieces1 revolves a soft iron shield in two sections1 these being the length of the armature and the same width as the heads4 ,as it revolves1 it forms bridges between the pole pieces and the core of the armature1 the lines of force flowing through it as well as through the armature4 ,the diagrams of ,fig4 #ac show the positions of the shield as it revolves about the armature4 ,in the first position1 one segment of the shield forms a bridge between the pole piece and the upper armature head1 while the other segment is bridging the space between the lower head and the other pole piece4 ,when in this position1 the lines of force flow through the neck of the armature and magnetize it so that it sets up its own field4 ,when the shield revolves so that it covers the heads1 the lines of force abandon the neck and flow between the pole pieces by the segments1 the field established by the neck dying out4 ,in the third position1 the lines of force again flow through the neck1 while in the fourth position1 with the shield completing a half revolution1 the lines of force again pass directly across4 ,in this half revolution there are therefore two periods when a magnetic field forms around the armature neck and dies out1 which will result in the induction of two currents in the winding of the armature4 ,if the revolution is continued it will be seen that the same conditions are repeated1 the positions of the two segments of the shield being reversed1 and that one revolution of the shield about the armature will produce four waves of current in the winding4 ,the magneto may therefore be driven at cam shaft speed for a four cylinder engine1 and in addition has the advantage of the wire windings being stationary4 ,the action of the magneto is the same as that of the two-spark type already described1 but the construction is simplified because the slow speed of the shield will permit the secondary distributor to be attached directly to the armature shaft1 the secondary shaft being done away with4 ,illustration3 ,,fig4 #ac4--;,,diagrams ,,showing ,,position ,,of ,,shield ,,revolving ,,about ,,armature4 ,a diagram of the wiring is shown in ,fig4 #ad4 ,the primary wiring is grounded1 and the live end brought out to the stationary contact point of the interruptor4 ,the moving part of the interruptor is pivoted in the center1 and the lower end1 a polished steel knob1 bears against the face of a disk that has four ribs running from center to edge4 ,when the knob is on the space between two of the ribs1 the interruptor closes the circuit1 but as the disk revolves and a rib touches the knob1 the arm moves on its pivot1 and the circuit is broken4 ,illustration3 ,,fig4 #ad4--,,wiring ,,diagram1 ,,four-,,spark ,,magneto4 ,the grounded end of the secondary winding is attached to the live end of the primary winding1 and its other terminal passes to a contact point carried on a hard rubber disk placed on the revolving shaft immediately in front of the interruptor4 ,the diagram shows a face view of this distributor1 as well as a side view4 ,a ring-shaped plate is set on one side of this disk1 and is in connection with a contact piece carried on the edge of the disk4 ,a carbon brush to which the live end of the secondary winding is attached is kept pressed against the ring-shaped plate1 and the secondary current is thus led to the contact piece on the edge of the disk4 ,as the disk revolves with the shaft of the shield the contact piece comes into successive contact with four carbon brushes1 which are connected to the spark plugs4 ,when the shield is in such a position that the lines of force flow through the neck of the armature1 the interruptor is closed1 but when the intensity of the current increases to the maximum the interruptor opens1 breaking the primary circuit1 and producing a rapid demagnetization of the armature core4 ,this dying out of the field induces a powerful current in the secondary winding1 which is led by the distributor to one of the spark plugs1 where it jumps the gap and returns to the winding by the ground connection4 ,,setting ,in setting the magneto the firing order of the engine is noted1 as has been explained1 and the magneto secured in position with its gear in mesh1 but loose on the shaft4 ,the cover over the space between the pole pieces will be found to be in the form of a shallow aluminum box1 which is held in position by a single screw with a large head1 and when this is removed the stationary armature and revolving shield will be exposed to view4 ,one of the pistons must then be brought into the position it will take with a fully advanced spark1 and the shield then revolved until it is in the position shown in ,fig4 #ae4 ,the nut securing the gear to the shaft may then be drawn up tight4 ,it will be noticed that one of the segments of the shield has a deep notch at each edge4 ,remembering the direction in which the shield will be driven1 the notch at the rear edge of the shield will indicate the position of the contact piece of the distributor which will then be coming into contact with the carbon brush of one of the stationary distributor contacts4 ,the spark plug of the cylinder that is in the firing position should be connected to the brush that the notch indicates as making contact1 and the remaining spark plugs and brushes connected according to the firing order4 ,illustration3 ,,fig4 #ae4--,,timing ,,diagram1 ,,four-,,spark ,,magneto4 ,,care ,the proper operation of the magneto requires the free and perfect action of the interruptor1 and this may be observed by means of a brass slide that operates on the arm or the spark control lever4 ,when this slide is raised1 the action of the interruptor may be watched4 ,like the two-spark ,bosch magneto1 the distance between these points when the disk separates them should be one sixty-fourth of an inch1 and contact should be made and broken without undue sparking4 ,the condenser that will be found in the shallow aluminum box covering the space between the pole pieces prevents sparking at the interrupter1 and is thrown into circuit automatically when it is placed in position4 ,the four-spark magneto is provided with a safety spark gap1 and when the points of one of the spark plugs are separated too far1 or when there is any interruption of the secondary circuit1 a spark will show there4 ,sparks should not be permitted to pass in the safety gap for any considerable period1 as damage will be done1 and when they indicate by their presence that something is wrong1 the trouble should be located and repaired without delay4 ,the regulation and care of the four-spark magneto is the same as has been described for the two-spark machine4 ,,dual ,,ignition ,,systems ,it has been the custom to equip jump-spark engines with two complete systems of ignition1 one operated by a magneto and the other by coil and battery4 ,each system has its own spark plugs1 timing device1 wiring1 etc41 the two being connected only at the switch4 ,many of these duplicate parts have been eliminated by the introduction of dual ignition systems1 and the mechanism is correspondingly simplified4 ,the ,bosch dual system is a good example of the principles involved1 and a diagram of the connections is shown on ,fig4 #af4 ,the magneto used is of the usual two-spark type1 except that the secondary current1 instead of being led from the collecting ring direct to the distributer1 is taken to the switch that is located in the coil box on the dash4 ,in addition to the regulation interrupter illustrated on ,fig4 #aa1 the magneto is provided with a second interrupter or circuit breaker that controls the flow of the battery current1 and takes the place of a timer4 ,while the magneto interrupter revolves with the armature1 and is operated by stationary cams1 the battery circuit breaker is stationary1 and is operated by a two-nose cam that revolves with the armature shaft4 ,the stationary and revolving cams are so set that the interrupter and circuit breaker break their circuits at the same instant4 ,the coil is contained in a brass case on the dash1 and in design and construction is a duplicate of the magneto armature4 ,attached to the coil is a handle that projects through a slot in the case1 by means of which the coil may be turned partly around in the case4 ,the terminals of the coil windings are attached to metal knobs located on the under side of a fiber plate that forms the bottom of the coil1 and turning the coil by the handle moves these knobs in and out of contact with corresponding knobs on the bottom of the case4 ,these knobs form the switch that cuts off all current1 or permits the engine to be run on magneto or battery4 ,when the switch is in such a position that the magneto produces secondary current1 this flows from terminal #c of the magneto to terminal #c of the switch2 thence by the switch connection to terminal #d and to the secondary distributer4 ,when the battery is switched in1 the magneto primary is grounded1 and secondary current from the coil flows over wire #d to the secondary distributer4 ,illustration3 ,,fig4 #af4--;,,bosch ,,jump-,,spark ,,dual ,,system4 ,by pressing a button on top of the coil case1 a vibrator is cut into the circuit to permit starting the engine on the spark4 ,when the engine starts the button is released1 and ignition is produced by the single spark that results from the demagnetizing of the core that follows the breaking of the battery circuit by the circuit breaker4 ,throwing the switch breaks the battery circuit and cuts in the magneto4 ,,inductor ,,magnetos ,in types of magnetos that have recently been produced1 the winding is stationary and surrounds a moving core that is magnetized and demagnetized during its revolution between the poles of the field magnets4 ,the ,remy magneto is of this type1 and ,fig4 #ag is a diagram of the revolving core1 or inductor1 with the coil surrounding it4 ,as the inductor revolves1 the magnetism flows from one pole of the field magnets into the wing of the inductor nearest to it1 through the central cylindrical part1 and by the second wing to the other pole1 the central part of the inductor then being magnetized4 ,the magnetism of this portion dies away when the wings are in such a position that they bridge across from one pole to the other1 but reappears when the central cylindrical part again becomes the only path by which the magnetism may flow4 ,the constant changes in the magnetic strength of the central part affect the coil1 and currents are induced in it4 ,these currents1 which are of low voltage1 are led to the primary winding of a secondary induction coil similar to that used in the ,eisemann system1 the secondary current flowing to the plugs through a distributer located on the magneto4 ,in the ,remy system1 the interrupter does not short circuit the magneto winding1 as is the case with the ,eisemann1 but the flow of current is from the magneto winding to the grounded side of the interrupter1 to the insulated screw1 to the primary winding of the coil1 and back to the magneto4 ,the interrupter is closed and the current flows in this circuit while the strength of the current is increasing1 but when the current is at a maximum the interrupter breaks the circuit1 the core of the coil loses its magnetism1 and a secondary current is induced4 ,the current reaches a maximum twice in each revolution4 ,illustration3 ,,fig4 #ag4--,,remy ,,inductor4 ,illustration3 ,,fig4 #ah4--;,,inductor ,,giving ,,six ,,waves4 ,in other magnetos1 the form of the inductor is such that six or more waves of current are produced during each revolution4 ,an inductor of this type is shown in ,fig4 #ah4 ,there are six arms radiating from the central cylindrical portion1 three at each end1 and equally spaced4 ,the coil is usually made of flat copper ribbon instead of wire1 and it surrounds the central cylindrical part between the two sets of arms4 ,in the inductor shown1 the magnetism of the central part will change strength six times to each revolution4 ,magnetos of this type are used to replace batteries in jump spark systems using vibrator coils4 ,they are driven by belt1 or by friction against the fly wheel1 and are given a speed at least three times that of the crank shaft4 ,by this means the waves of current follow one another at such brief intervals that the flow is practically continuous1 and it is therefore unnecessary to time the magneto to the engine4 ,these magnetos have no interrupters1 and the wiring consists of one wire leading to the switch on the coil box1 the usual connections between the coil box and timer1 and a wire from the second magneto terminal to ground4 ,,magnetic ,,make-,,and-,,break ,,system ,the flaming spark produced by the make-and-break system has many advantages for ignition over the jump spark produced by the high-tension system1 but these are largely offset by the mechanical complication of cams1 tappets1 springs1 etc4 ,a make-and-break system in which the igniters are operated by magnetism has been perfected by the ,bosch company1 and is giving good results4 ,the magneto used is of the ordinary low-tension type1 equipped with an interrupter1 while all of the igniter parts are contained in a plug that screws into the cylinder wall like a jump-spark plug4 ,the plug is shown in diagram in ,fig4 #ai4 ,the sleeve that screws into the cylinder supports an iron core1 the two being thoroughly insulated by blocks and washers of heat-proof insulating material4 ,the upper portion of the core has a flat side1 on which is formed a projection that serves as a pivot4 ,a hammer bar is balanced on this pivot1 its long end passing through the plug and coming into contact with an anvil attached to the screwed sleeve4 ,a long horseshoe-shaped spring holds the two in light contact1 and the hammer bar then forms the only path by which an electric current may pass from the core to the screwed sleeve and to the engine ground4 ,when the hammer bar is moved on its pivot this connection is broken4 ,surrounding the core is a coil consisting of a few layers of wire covered with heat-proof insulation4 ,the upper part of the plug is incased in a light iron casing screwed to the core1 which completely incloses the core1 hammer bar1 spring and coil1 and in which there is no opening that would permit the escape of compression from the combustion chamber4 ,one terminal of the coil is connected to the binding post1 and the other is grounded on the iron casing4 ,the current generated in the magneto passes to a distributer and thence to the binding post of the plug1 as shown in ,fig4 #bj4 ,it flows through the coil to the core1 and thence by the hammer bar to the engine ground and back to the magneto4 ,as the current establishes itself in the coil1 the core becomes magnetized1 and attracts to it the flat end of the hammer bar4 ,when the hammer bar moves on its pivot1 its connection with the anvil is broken1 and this break in the circuit produces a flaming spark that is in every way identical with the spark of the ordinary mechanical make-and-break igniter4 ,the casing that contains the coil may be unscrewed from the core without disturbing the screwed sleeve1 and this makes it an easy matter to give the moving parts the inspection and cleaning that they should receive every few weeks4 ,the spark occurs in the plug at the instant that the interrupter operates1 and the setting up of the system is identical with that of the high-tension magneto systems4 ,illustration3 ,,fig4 #ai4--,,magnetic ,,igniter4 ,illustration3 ,,fig4 #bj4--,,wiring ,,diagram ,,of ,,magnetic ,,igniter ,,system4 ,a ,,handy ,,testing ,,chart99 ,,what ,,to ,,do ,,when ,,the ,,engine ,,stops ,arranged for the ,scientific ,american 7,copyright1 #aiji1 by ,munn ,co47 ,,effects ,,of ,,trouble ,engine ,test ,ignition and will carbureter4 not ,slow cranking or cold weather will interfere with start4 the proper formation or the mixture4 ,prime cylinders with gasoline in cold weather to obtain mixture for starting4 ,to increase suction in carbureter1 prevent operation of air-valve4 ,engine starts1 but will not ,fuel does not flow freely to carbureter4 continue ,weak battery4 running4 ,explosions ,break in ground wire1 battery cease connections1 switch lead4 abruptly4 ,engine runs ,worn timer4 well slowly1 ,weak battery4 but misses ,faulty vibrator adjustment4 when speeded ,faulty carbureter adjustment4 up4 ,fuel does not flow freely to carbureter4 ,engine will ,preignition4 not stop4 ,glowing carbon or metal point in cylinder4 ,engine too hot 7see ,cooling trouble74 ,engine does ,faulty setting of valves4 not deliver ,tight bearings or broken balls4 full power4 ,indicated by excessive heating4 ,back pressure4 ,fouled muffler4 ,dragging brakes4 ,friction in transmission4 ,faulty carburetion4 ,weak ignition4 ,weak compression4 ,overheating4 ,slipping timer4 ,loose half-time shaft4 ,sticking air-valve4 ,irregular ,intermittent obstruction in spray nozzle4 miss4 ,sticking valve4 ,broken or weak valve-spring4 ,loose connection4 ,short circuit4 ,engine noises4 ,knocking4 ,too much retard of spark4 ,preignition4 ,worn bearings4 ,loose or cracked flywheel4 ,hissing4 ,broken piston rings4 ,leaking air inlet pipe or gasket4 8,popping0 in carbureter4 ,leaking inlet valve4 ,weak mixture4 ,excessive retard of spark4 ,explosions weaken and ,carbureter or fuel trouble4 cease4 ,engine will ,weak magneto4 not run ,faulty carbureter adjustment4 slowly4 ,steady miss in one or more cylinders1 ,vibrator1 timer1 secondary circuit4 7other cylinders firing normally74 ,,ignition4 ,test primary circuit ,jump spark1 as described for with single system using coils coil1 battery and timer4 secondary ,secondary may distributor4 short circuit from ,fouled or worn distributor4 ,defective insulation4 ,,ignition4 ,to test1 revolve crank-shaft ,jump spark1 twice1 listening with battery1 for vibrators4 timer and coils4 ,,test #a4 ,alternate test1 prime cylinders with a few drops of gasoline1 close relief cocks1 and crank4 ,explosions show ignition to be ,o4 ,k4 ,all vibrators sound normal1 primary circuits ,o4 ,k4 unless timer has slipped on shaft4 ,vibrator should begin to operate as a piston gets to top center of compression1 with spark lever retarded4 ,one or more vibrators sound normal1 ,to test coils1 short showing that circuit the timer battery connections1 by making contact lead and between primary ground wires1 and terminal of battery are ,o4 ,k4 coil and ground4 ,vibrator normal1 coil is ,o4 ,k41 look for ,interruption in timer circuit4 ,blade moves1 but will not vibrate4 ,punctured condenser 7#a74 ,short circuit at vibrator4 ,vibrator does not operate4 ,faulty adjustment4 ,too stiff4 ,will operate only with strong battery4 ,excessive sparking at vibrator1 and battery exhausts rapidly4 ,too weak4 ,feeble secondary spark2 misfiring with slightly corroded contacts4 ,contacts corroded4 ,contacts stuck4 ,vibrators do not operate4 ,open switch2 vibrator trouble4 ,trouble in battery or in primary circuit4 ,to test1 make momentary contact from switch terminal to ground4 ,bright spark1 battery lead and ground wire ,o4 ,k4 ,weak or no spark4 ,break in battery connections1 lead or ground wire4 ,battery exhausted or dry cells polarized4 ,to test secondary1 disconnect spark plug leads1 support them inch from engine ground and crank4 ,good spark1 ,o4 ,k4 ,weak spark4 ,no spark4 ,vibrator trouble4 ,plug short circuited1 fouled1 oily4 ,points too far apart--should be #a_/cb inch4 ,short circuit in secondary4 ,broken condenser connection 7#a74 ,shown by brilliant sparking at vibrator4 ,explosions4 ,ignition ,o4,k4 unless ,,ignition4 ,magneto is out of time and igniters incorrectly adjusted4 ,make and break1 ,should break circuit at top center with low of compression when spark is retarded4 tension magneto4 ,no explosions4 ,short circuit4 ,use ,test #a1 ,insulated bridge on magneto4 cranking ,switch or switch lead4 briskly4 ,bus-bar or bus-bar lead4 ,igniter insulator broken4 ,igniter stuck closed4 ,broken spring4 ,tappet stuck in guide4 ,to test operate by hand4 ,open circuit4 ,magneto broken down4 ,to test magneto1 disconnect magneto lead from bus-bar and hold free end in bare fingers1 or ,,test #b4 ,hold free end against teeth of metal gear and crank briskly4 ,shock or spark4 ,magneto ,o4 ,k4 ,no shock or spark4 ,fouled collecting brush4 ,armature burned out #a4 ,fields demagnetized #a4 ,to test1 unmesh gear1 revolve armature by hand4 ,if fields are ,o4 ,k41 armature should turn perceptibly hard twice in each revolution4 ,,carbureter4 ,mixture ignites4 ,proving that carbureter is doing its duty4 ,to test1 hold ,mixture does not ignite4 ,operate primer to flood lighted match float chamber4 over open relief ,gasoline drips from spray nozzle4 cocks while ,mixture too rich4 engine is ,insufficient air4 cranked briskly4 ,faulty adjustment of air valve4 ,clogged inlet pipe4 ,dust on inlet pipe screen4 ,leaking float valve4 ,float too heavy4 ,soggy 7if of cork7 7#b74 ,punctured 7if of metal7 7#c74 ,faulty adjustment of float4 ,mixture too poor4 ,too much air4 ,water in gasoline4 ,faulty adjustment of air-valve4 ,leaks in inlet pipe4 ,faulty adjustment of float4 ,no drip from spray nozzle4 ,clogged spray nozzle4 ,clogged float valve4 ,clogged fuel feed4 ,no gasoline4 ,empty tank4 ,closed supply cock4 ,,ignition4 ,proceed as in ,test #a1 cranking briskly4 ,explosions4 ,jump spark with ,ignition ,o4 ,k4 unless magneto is out of time4 low tension ,should be reset4 magneto and coil ,sparks in safety spark gap4 7,eisemann1 ,remy1 ,interruption in secondary circuit4 ,splitdorf1 etc47 ,too wide a gap at plugs 7should be from #a_/fd to #a_/cb inch74 ,no explosions4 ,primary circuit open4 ,primary short circuit4 ,magneto broken down4 ,to test magneto1 disconnect primary lead to coil and proceed as in test #b4 ,shock 7or spark71 magneto ,o4 ,k4 ,no shock 7or spark74 ,interrupter short circuited1 wet or oily4 ,field demagnetized 7#a74 ,condenser broken down 7shown by brilliant spark at interrupter7 7#a74 ,coil broken down4 ,to test primary winding of coil disconnect ground wire and proceed as in second part of test #b4 ,spark1 winding ,o4 ,k4 ,no spark4 ,winding broken 7#a7 down or short or open circuited4 ,to test secondary winding of coil1 disconnect spark plug leads from magneto and crank briskly1 watching for sparks at safety spark gap4 ,sparks1 look for ,plugs short circuited4 ,fouled4 ,insulation broken down4 ,fused metal bead at points4 ,secondary short circuit 7#a74 ,leads short circuited4 ,ground circuit open4 ,no sparks1 winding broken down4 ,,ignition4 ,proceed as in ,test #a1 cranking briskly4 ,explosions4 ,high tension ,ignition ,o4 ,k4 unless magneto is out of time4 magneto 7,bosch1 ,should be reset4 ,u4 ,h4 ,lacoste1 ,sparks in safety spark gap4 ,witherbee1 etc47 ,break in secondary circuit4 ,too wide a gap at plugs 7should be from #a_/fd to #a_/cb inch74 ,no explosions4 ,to test magneto1 disconnect spark plug leads from distributor and crank briskly1 watching for sparks at safety spark gap4 ,sparks4 ,magneto ,o4 ,k4 ,look for short circuits in ,spark plugs4 ,fouled4 ,insulation broken down4 ,bead of fused metal between points4 ,switch lead4 ,switch4 ,no sparks4 ,corroded interrupter contacts4 ,interrupter stuck4 ,armature burned out 7#a74 ,condenser broken down 7#a74 ,field demagnetized 7#a74 ,,fuel ,,feed ,to test1 open drain cock at carbureter4 ,,system4 ,gasoline flows4 ,system is ,o4 ,k4 ,gasoline does not flow4 ,gravity feed4 ,clogged vent hole in filling cap4 ,clogged piping 7#d74 ,pressure feed4 ,sufficient pressure in tank4 ,clogged piping 7#d74 ,insufficient pressure in tank4 ,leaking tank or piping4 ,leaking filling cap4 ,stuck relief valve4 ,to test1 crank engine slowly1 noting resistance1 which should be the same in all cylinders4 ,,compression4 7,do not confuse constant mechanical resistance with intermittent resistance of compression74 ,inject oil into faulty cylinder4 ,improved compression indicates ,stuck piston rings4 ,douse cylinder with kerosene and alcohol and to cut carbon4 ,worn or scored piston rings4 ,scored cylinder walls4 ,no improvement in compression indicates ,worn or pitted valves4 ,leaking spark plug1 igniter plate1 relief cock1 etc4 ,test by running oil around these and cranking4 ,leak indicated by bubbles4 ,piston ring splits in line4 ,broken piston rings4 ,crank case will be abnormally warm4 ,cracked walls or head4 ,indicated by water in cylinder4 ,sticking valves4 ,insufficient space between valve stem and push rod4 ,radiator should heat evenly shortly ,,cooling4 after engine is started4 ,radiator does not heat4 7,water47 ,clogged circulation system4 ,empty tank4 ,clogged piping4 ,defective pump4 ,test by opening pet cocks4 ,radiator steams4 ,failure of lubrication4 ,indicated by groans from cylinders affected4 ,supply should be just sufficient to produce faint whiff of blue smoke at exhaust4 ,defect in circulation4 ,too much running on retarded spark or on low speed4 ,slipping fan drive4 99 ,it is taken for granted that the engine is capable of running properly1 that the tanks are filled1 and that the switch is correctly thrown4 #a ,return to makers for repair4 #b ,dry in oven1 and coat with shellac4 #c ,plunge in hot water to expel gasoline and to locate leak4 ,repair with solder4 #d ,may be cleared with blast from foot pump4 ,,index ,adjusting screw for vibrator1 #ajc4 ,advance of ignition1 #ac4 ,advancing ignition by moving timer1 #aja4 too far1 #ac4 ,air cooling1 #cd4 requisites for1 #ce4 ,air inlet1 auxiliary1 adjustment of1 #bca4 ,air intake trouble1 #aig4 ,amperes1 #gg4 ,antifreezing mixture1 #bjj4 ,antiskid devices1 use of1 #agd4 ,armature of generator1 #hh1 #bef4 ,assembling springs1 #bbi4 ,automatic carburetor1 #eh4 ,automatic valve1 #be4 action of1 #bf4 adjustment of1 #bcc4 spring of1 #bg4 ,auxiliary air1 necessity for1 #ef4 ,auxiliary air inlet1 action of1 #eg4 adjustment of1 #bca4 ,axle1 dead rear1 #aeb4 live rear1 #adf4 necessity for fixed front1 #afb4 rear1 floating1 #adh4 sprung1 effect of1 #adh4 ,back pressure1 #ah4 ,backfiring1 causes of1 #bah4 ,balance of engines1 #cg4 ,band brake1 #afg4 ,battery1 causes of trouble in1 #ahb4 cross-connected1 #ahb4 nearly exhausted1 #ahc4 recuperation of1 #ahc4 weak1 effect of1 #bac4 ,battery connections1 #hd4 ,bearings1 tight1 effect of1 #baj4 tight1 testing for1 #bba4 ,bevel gears1 necessity for1 #adb4 ,bosch magnetos1 #cja1 #cjh1 #cag1 #cbc4 ,brake1 motor as1 #agj4 ,brake equalizer1 #agb4 ,brakes1 #afg4 emergency and running1 #afi4 tight1 effect of1 #baj4 testing for1 #bba4 ,broken wire1 #aha4 ,bus bar1 #bjd4 ,cam1 #bf4 action of1 #bf4 parts of1 #bf4 worn1 effect of1 #bce4 ,cam shaft1 #bh4 ,carbon deposit from burned oil1 #ca4 ,carburetion1 #eb4 ,carburetor1 action of1 #ee4 adjustment of1 #bca4 automatic1 #eh4 cleaning of1 #aif4 dirt and water in1 #aie4 effect of varying speed on1 #ef4 float feed1 #ec4 flooding of1 #aie4 mechanically controlled1 #eh4 necessity for1 #ec4 necessity for auxiliary air in1 #ef4 parts of1 #ec4 principle of1 #ec4 surface1 #fd4 testing of1 #bjg4 trouble in1 causes of1 #aie4 types of1 #eh4 with central mixing chamber1 #fa4 with side mixing chamber1 #fj4 ,carburetor adjustments1 #eh4 ,chains1 care of1 #bbe4 cleaning and lubricating of1 #bbe4 driving1 adjusting of1 #bbe4 ,change speed mechanism1 friction type of1 #ada4 individual clutch type of1 #ach4 necessity for1 #aai4 planetary type of1 #acb4 sliding gear type of1 #abj4 ,changing gear1 principle of1 #abe4 ,charging of storage battery1 #hb4 ,check and relief valves1 #gb4 ,chemical generators1 #hj4 ,circuit breaker1 magneto1 #bhf4 ,circuit1 jump spark system1 #ajh4 primary1 testing of1 #bjf4 primary and secondary1 #aji4 parts of1 #ig4 secondary1 testing of1 #bab4 ,circulation1 failures of1 #aii4 ,circulation connections1 troubles of1 #aii4 ,circulation of water1 forced and gravity1 #cb4 ,classes of gasoline engines1 #e4 ,cleaning1 use of kerosene for1 #bbd4 ,cleaning carburetor1 #aif4 chains1 #bbe4 combustion space1 #bbc4 crank case1 #bbd4 differential1 #bbd4 gear case1 #bbd4 lubricator pipes1 #bjb4 spark plug1 #ahg4 tires1 #bbb4 ,clearance1 #ag4 ,closing of exhaust valve1 #ag4 of inlet valve1 #h4 ,clutch1 action of1 #aac4 friction cone1 #aac4 internal expanding1 #aah4 multiple disk1 #aad4 parts of1 #aaf4 necessity for1 #aab4 reversed friction cone1 #aad4 slipping of1 effect of1 #baj4 withdrawing of1 when changing gear1 #aac4 ,coil trouble1 causes of1 #ahf4 ,coils1 matching of1 to cylinders1 #bcj4 testing of1 #bjf4 ,cold1 effect of1 on starting engine1 #bji4 ,combustion1 pressure from1 #d4 ,combustion and explosion1 #d4 ,combustion space1 #h4 carbonized1 effect of1 #bae4 cleaning of1 #bbc4 ,commutator1 #ig4 ,compensating gear 7see ,differential74 ,compression1 during exhaust stroke1 #af4 effect of1 #aj4 on spark1 #ahh4 necessity for1 #aj4 ,compression leaks1 #aig4 testing for1 #baa4 ,compression limit1 #ad4 ,compression trouble1 causes of1 #aig4 ,compression-combustion stroke1 #h4 ,condenser1 action of1 #aji4 ,conductors and insulators1 #gf4 ,cone clutch1 friction1 #aac4 ,connecting rod1 #bc4 ,connections1 battery1 #hd4 loose1 effect of1 #bab1 #bac4 making1 #ahj4 of secondary distributer1 #aaa4 ,construction of bevel gear differential1 #aec4 of primary induction coil1 #ic4 of secondary induction coil1 #if4 of spark plug1 #ajg4 of spur gear differential1 #aeg4 of switch1 #hi4 ,contracting brake1 #afg4 ,control of steering1 #afd4 ,coolers1 #cb4 ,cooling1 air1 #cd4 requisites for1 #ce4 failure in1 effect of1 #bae4 water1 #ca4 ,cooling cylinder1 necessity for1 #cj4 ,cooling system freezing1 #bjj4 ,cooling systems1 #ca4 ,cooling trouble1 causes of1 #aii4 ,cooling water1 flow of1 #ca4 ,corrosion1 effect of1 #aha4 ,crank case1 cleaning of1 #bbd4 depth of oil in1 #bbd4 ,crank pin1 #bc4 ,crank shaft1 #bj4 four-cylinder engine1 #dc4 #ahj-1 effect of1 #ci4 #cfj-1 effect of1 #da4 ,crank shaft points1 #bb4 ,crank shaft throws1 #ch4 ,cranks1 relative positions of1 #bb4 ,current1 flow of1 #ge4 induced1 #id4 secondary1 #ig4 ,cycle1 #d4 events of1 #f4 strokes of1 #f4 ,cylinder1 #be4 faulty1 testing for1 #bab4 matching coils1 to1 #bcj4 necessity for cooling1 #cj4 ,cylinder head1 #e4 ,defects of surface carburetors1 #fd4 ,deposit from burned oil1 #ca4 ,differential1 bevel gear1 construction of1 #aec4 cleaning of1 #bbd4 location of1 #aeh4 necessity for1 #aeb4 operation of1 #afe4 spur gear1 construction of1 #aeg4 ,direct drive1 #abd4 ,disk1 valve1 #be4 ,disk clutch1 #aad4 ,distance rods1 necessity for1 #agf4 ,distributer1 causes of trouble in1 #aib4 secondary1 #aaj4 ,double-acting brake1 #afg4 ,double-chain drive1 #aej4 ,double-opposed engine1 #ch4 ,drag link1 #afb4 bent1 effect of1 #bbh4 ,drive1 double chain1 #aej4 driving shaft1 #add4 final1 #adb4 propeller or driving shaft1 #add4 single chain1 #adb4 ,drives1 advantages of different types of1 #aeh4 ,driving chains1 adjusting of1 #bbe4 ,driving gear ratios1 #aei4 ,dry cells1 #hj4 voltage of1 #ha4 ,dynamo1 action of1 #hh4 ,eisemann system1 #bhc et seq4 ,electric current1 generation of1 by magnetism1 #hg1 #bed4 production of1 #hj4 ,electrical measurements1 #gg4 ,electrolyte1 #hb4 ,electro-magnet1 #hg1 #bec4 ,emergency brake1 #afi4 ,engine1 care of1 #bbc4 distinction between two-cycle and four-cycle1 #e4 effect of cold on starting1 #bji4 failure of1 to deliver full power1 #bji4 to start1 #bjh4 four-cycle1 #e4 missing of1 at high speed1 #bac4 parts of1 #bj4 starting1 then stopping of1 #bad4 stopping of1 #baf4 timing of1 #bcb4 two-cycle1 #dg4 two-cycle1 action of1 #di4 vibration of1 #cg4 ,engine as a brake1 #agj4 ,engine balance1 #cg4 four-cylinder1 #da1 #dc4 ,h4 ,d4 ,o41 #ch4 three- and six-cylinder1 #dd4 two-cylinder1 #ch4 ,engine types1 advantages and disadvantages of1 #de4 ,epicyclic gears 7see ,planetary74 ,equalizer1 brake1 #agb4 ,events of cycle1 #f4 ,exhaust stroke1 #af4 compression during1 #af4 ,exhaust valve1 closing of1 #ag4 opening of1 #ae4 ,expanding brake1 #afg4 ,expanding clutch1 #aah4 ,explosion and combustion1 #d4 ,explosions1 missing1 #baa4 weak1 #baj4 ,field1 magnetic1 #hh1 #bea4 of generator1 #hh4 ,final drive1 #adb4 ,firing order1 #dd4 ,float1 punctured1 #aif4 ,float and float chamber1 carburetor1 #ec4 ,float feed carburetor1 #ec4 ,floating rear axle1 #adh4 ,flow of cooling water1 #ca4 of current1 #ge4 of electricity1 definition of1 #gi4 ,fly wheel1 necessity for1 #h4 vibration absorbed by1 #cg4 weight of1 #db4 ,force circulation of water1 #cb4 ,fouled spark plug1 causes of1 #ahg4 ,four-cycle engine1 #e4 ,four-cylinder engine balance1 #dc4 ,four-cylinder engine crank shaft1 #dc4 ,four-cylinder engines1 #dc4 ,freezing of water1 #bjj4 ,friction transmission1 #ada4 ,gases1 properties of1 #a4 ,gasoline1 dirt and water in1 #aic4 separating water from1 #aic4 spraying1 necessity for1 #eg4 ,gasoline engine1 action of1 #d4 classes of1 #e4 functions of 7see ,cycle74 not self-starting1 #ah4 power of1 #ah4 without reserve power1 #ai4 ,gasoline feed pipe trouble1 causes of1 #aie4 ,gasoline feeds1 gravity and pressure1 #ff4 ,gasoline line1 trap on1 #gc4 ,gasoline strainer1 #gc4 ,gasoline trouble1 causes of1 #aic4 ,gasoline vapor1 #eb4 ,gear case1 cleaning of1 #bbd4 ,gears1 two-to-one1 #bh4 ,generator field and armature1 #hh4 ,generator terminals or poles1 #ge4 ,generators of electric current1 #ha4 ,governor-controlled carburetor1 #fb4 ,gravity feed of gasoline1 #ff4 ,gravity system of water cooling1 #cd4 ,grinding valves1 #bbf4 ,grounding the return1 #gi4 the secondary circuit1 #ajh4 the timer1 #aja4 ,gudgeon pin 7see ,wrist ,pin74 ,half time shaft1 #bh4 ,heat1 #a4 excessive1 result of1 #cj4 losses1 #ae4 produced through resistance1 #gg4 ,horizontal double-opposed engine1 #ch4 ,hydrometer1 #hc4 ,igniter1 #ia1 #bfh4 adjustment of1 #bgf4 magnetic1 #cbc4 ,igniter bearing1 #aij4 ,igniter contacts1 #aij4 ,igniter points1 setting1 #ahi1 #bgf4 ,igniter tappet1 #ib4 spring of1 strength of1 #aij4 ,igniter trouble1 causes of1 #ahi4 ,ignition1 affected by improper mixture1 #ab4 affected by speed1 #ab4 necessity for1 #h4 necessity for early1 #aa4 speed controlled by1 #ad4 too far advanced1 #ac4 too far retarded1 #ac4 ,ignition advance1 #ac4 ,ignition lead 7see ,necessity for ,early ,ignition74 ,ignition retard1 #ac4 ,ignition system1 parts of1 #ge4 purpose of1 #gd4 ,ignition systems1 #ia4 ,ignition testing1 #bjc4 ,ignition timing1 #aib4 ,ignition trouble1 causes of1 #agi4 ,ignition wiring1 #bcf4 ,imperfect combustion of mixture1 #aj4 ,improper mixture1 ignition affected by1 #ab4 ,individual clutch1 #ach4 ,induced current1 #id1 #bed4 ,induction and magnetism1 #ic1 #bed4 ,inductor magnetos1 #cai4 ,inflation of tires1 #agc4 ,inlet pipe1 #ec4 ,inlet stroke1 #h4 ,inlet valve1 closing of1 #h4 ,inspection of car1 #bbj4 ,insulators1 #gf4 ,interrupter points1 smoothing1 #bie4 ,irreversible steering mechanism1 #afe4 ,jack shaft1 #aeb4 ,jackets1 water1 #ca4 ,joints universal1 necessity for1 #add4 ,jump spark system1 action of1 #if4 circuit of1 #ajh4 ,jump spark trouble1 location of1 #bje4 ,jump spark wiring1 #bch4 ,kerosene1 use of1 for cleaning1 #bbd4 ,knocks1 #bag4 ,lead and return wires1 #gh4 ,leaks of compression1 #aig4 ,limit of compression1 #ad4 ,lines of force1 magnetic1 #hg1 #bea4 ,live rear axle1 #adf4 ,losses of heat1 #ae4 ,low tension system1 action of1 #ia1 #bgj4 ,lubrication1 #cd1 #ce4 of chains1 #bbe4 of springs1 #bbi4 ,lubrication systems1 #cf4 ,lubrication table1 #bdd4 ,lubrication troubles1 #bja4 ,lubricator failure1 effect of1 #bae4 ,lubricator pipes1 cleaning of1 #bjb4 ,magnetic field1 #hh1 #bea4 ,magnetic lines of force1 #hg4 ,magnetic make-and-break system1 #cbc4 ,magnetic vibrator1 #ajc4 ,magnetism1 #hf1 #bde4 electric current generated by1 #hg4 test for1 #bfe4 ,magnetism and induction1 #ic1 #bed4 ,magneto1 action of1 #hh1 #ie4 classification1 #bfa4 drives1 #bfc4 dual systems1 #cjj1 #caf4 effect of changing speed1 #bfb4 ,eisemann1 care of1 #bid4 high tension1 four spark1 #cjh4 interrupter1 #bhf4 low tension1 ignition by1 #beh4 wiring of1 #bgb4 with secondary coil1 #bhc4 parts1 #bef4 preserving magnetism of1 #bff4 principles1 #bee et seq4 removing armature of1 #ahc1 #bff4 ,remy1 #cbj4 retention of magnetism of1 #ahd1 #bff4 safety spark gap1 #bhi4 starting engine with1 #bfc4 testing1 #bfd4 ,magneto setting1 #ahe1 #bgd1 #cjf4 ,magneto troubles1 causes of1 #ahc1 #bfd4 ,magnetos1 ,bosch1 #cja1 #cjh1 #cag1 #cbc4 high tension1 care of1 #cje4 principles of1 #big4 setting1 #cjc4 high tension1 troubles of1 #cjf4 inductor type1 #cai4 magnetic make-and-break1 #cbc4 ,magnets1 permanent and electro-1 #hg1 #bdi1 #bec4 ,maintenance and construction1 #bbj4 ,make-and-break ignition1 action of1 #ia1 #bgj4 ,make-and-break trouble1 location of1 #bjf4 ,make-and-break wiring1 #bdj4 ,measurements1 electrical1 #gg4 ,mechanical generator1 action of1 #hf4 care of1 #hh1 #hi4 ,mechanical vibrator1 #ajc4 ,mechanically-controlled carburetor1 #eh4 construction of1 #fb4 ,mechanically operated valve1 action of1 #bf4 ,mixing chamber1 carburetor1 #ec4 central1 #fj4 side1 #fj4 ,mixture1 imperfect combustion of1 #aj4 ,muffler1 necessity for1 #cj4 ,muffler explosions1 causes of1 #bai4 ,multiple connection of battery1 #he4 ,multiple disk clutch1 #aad4 parts of1 #aaf4 ,necessity for auxiliary air in carburetor1 #ef4 for bevel gears1 #adb4 for carburetor1 #ec4 for change-speed mechanism1 #aai4 for clutch1 #aab4 for compression1 #aj4 for cooling cylinder1 #cj4 for differential1 #aeb4 for distance or radius rods1 #agf4 for early ignition1 #aa4 for fixed-front axle1 #afb4 for fly wheel1 #h4 for ignition1 #h4 for muffler1 #cj4 for spraying the gasoline1 #eg4 for switch1 #hi4 for timer1 #ih4 for torsion rod1 #adh4 for universal joints1 #add4 for valves1 #h4 for vibrator1 #ajb4 for withdrawing clutch when changing gear1 #acj4 ,negative pole1 #gf4 ,noises1 #bag4 ,nonconductors1 #gf4 ,ohms1 #gh4 ,oil1 burned1 deposit from1 #ca4 depth of1 in crank case1 #bbd4 ,opening of exhaust valve1 #ae4 ,operation of differential1 #aee4 ,overheating1 #bae4 ,overheating1 causes of1 #aii4 warning of1 #baf4 ,parallel connection of battery1 #he4 ,parts of engine1 #bj4 of cam1 #bf4 of carburetor1 #ec4 of ignition system1 #ge4 of magneto1 #bef4 of multiple disk clutch1 #aaf4 of primary circuit1 #ig4 of secondary circuit1 #ig4 ,permanent magnet1 #hg4 ,piston1 #bc4 stuck1 #baf4 ,piston pin 7see ,wrist ,pin74 ,piston rings1 #bd4 care of1 #bbc4 setting of1 #aih4 trouble of1 #aih4 ,planetary gear action1 #acf4 ,planetary type of change-speed mechanism1 #acb4 ,points1 crank shaft1 #bb4 ,poles1 positive and negative1 #gf4 ,poles of generator1 #ge4 ,ports of two-cycle engine1 #dg4 ,positive pole1 #gf4 ,power of gasoline engine1 #ah4 of steam engine1 #ah4 ,power stroke1 #ae4 ,preignition1 causes of1 #bae4 ,pressure circulation of water1 #cb4 ,pressure feed of gasoline1 #ff4 ,pressure from combustion1 #d4 ,primary circuit1 #aji4 parts of1 #ig4 testing of1 #bjf4 ,primary generators1 #hj4 ,primary induction coil1 use of1 #ic4 ,production of electric current1 #hj4 ,progressive type sliding gear1 #aba4 ,propeller-shaft drive1 #add4 ,properties of gases1 #a4 ,protection of tires1 #bbb4 ,pumps1 water1 #cb4 ,purpose of ignition system1 #gd4 ,push rod1 #bh4 ,radiators1 #cb4 ,radius rods1 necessity for1 #agf4 ,ratios1 driving gear1 #aei4 ,rear axle1 dead1 #aeb4 ,reason for skidding1 #agd4 ,recuperation of battery1 #ahc4 ,relative positions of cranks1 #bb4 ,remy magneto1 #cbj4 ,renewing vibrator contacts1 #ahf4 ,replacing valve springs1 #bbg4 ,requisites for air cooling1 #ce4 ,resistance1 #gf4 heat produced by1 #gg4 ,retard of ignition1 #ac4 too far1 #ac4 ,return1 grounding the1 #gi4 ,return wire1 #gh4 ,reverse1 action of1 #abe4 ,reversible steering mechanism1 #afd4 ,revolution and stroke1 #e4 ,rings1 piston1 #bd4 ,rod1 radius1 necessity for1 #agf4 torsion1 necessity for1 #adh4 valve lifter1 #bh4 ,running brake1 #afi4 ,running gear1 #afa4 ,seat1 valve1 #be4 ,secondary cells1 #hj4 ,secondary circuit1 #aji4 grounding of1 #ajh4 parts of1 #ig4 testing of1 #bab4 ,secondary current1 #ig4 ,secondary distributer1 #aaj1 #bhg4 causes of trouble in1 #aib4 ,secondary induction coil1 use of1 #if4 ,secondary shaft1 #bh4 ,selective type1 advantages of1 #abi4 of sliding gear1 #abf4 ,series connection of battery1 #he4 ,setting igniter points1 #ahi4 ,setting magneto1 #ahe4 ,setting piston rings1 #aih4 ,shaft1 cam1 #bh4 jack1 #aeb4 ,shock absorbers1 #agf4 ,short circuit1 definition of1 #gi4 causes of1 #ahg4 ,side chain drive1 #aej4 ,silencer1 #cj4 ,single-acting brake1 #afg4 ,single chain drive1 #adb4 ,six-cylinder engine balance1 #dd4 ,skidding1 reason for1 #agd4 ,sliding gear1 action of1 #abj4 progressive type of1 #aba4 selective type of1 #abf4 ,spark1 effect of compression on1 #ahh4 ,spark gap1 size of1 #ahh4 ,spark plug1 #ajf4 cleaning of1 #ahi4 distance between points of1 #ahh4 fouled1 effect of1 #bab4 trouble in1 causes of1 #ahg4 ,sparking in timer1 #ajh4 ,speed1 control of1 by ignition1 #ad4 effect of varying1 on carburetor1 #ef4 excessive1 results of1 #ai4 ignition affected by1 #ab4 ,spray nozzle1 carburetor1 #ee4 ,spraying gasoline1 necessity for1 #eg4 ,springs1 assembling1 #bbi4 automatic valve1 #bg4 care of1 #bbh4 lubrication of1 #bbi4 vehicle1 action of1 #age4 ,steam engine1 action of1 #b4 power of1 #ah4 ,steering1 #afa4 control of1 #afd4 principle of1 #afc4 ,steering arm1 bent1 effect of1 #bbh4 ,steering knuckles1 #afb4 ,steering mechanism1 care of1 #bbg4 irreversible1 #afe4 reversible1 #afd4 ,stem1 valve1 #be4 ,storage battery1 charging of1 #hb4 ,storage cell1 action of1 #ha4 terminals of1 #hc4 voltage of1 #hd4 ,strainer1 gasoline1 #gj4 ,stratified mixture 7see ,imperfect ,combustion of ,mixture74 ,stroke and revolution1 #e4 ,strokes of cycles1 #f4 ,sun and planet gears 7see ,planetary74 ,surface carburetors1 #fd4 ,switch1 necessity for1 #hi4 ,switch trouble1 causes of1 #aic4 ,systems1 cooling1 #ca4 ,tank1 air-bound1 #aid4 ,tank trouble1 causes of1 #aid4 ,tappet1 igniter1 #ib4 spring of1 #ib4 strength of1 #aij4 ,terminals of generator1 #ge4 of storage cells1 #hc4 ,testing carburetor1 #bjg4 coils1 #bjf4 electrolyte1 #hc4 for compression leaks1 #baa4 for faulty cylinder1 #bab4 for tight bearings and brakes1 #bba4 ignition1 #bjc4 ,testing1 make-and-break1 #bjd4 primary circuit1 #bjf4 secondary circuit1 #bab1 #bac4 ,thermosiphon system of water cooling1 #cd4 ,three-cylinder engine balance1 #dd4 ,throttle1 #fb4 worn connections of1 effect of1 #bcb4 ,throws1 crank shaft1 #ch4 ,timer1 #ig4 control rods of1 effect of wear on1 #aia4 grounding of1 #aja4 loose on shaft1 #aia4 moving of1 to advance ignition1 #aja4 necessity for1 #ih4 setting of1 #aib4 sparking in1 #ajf4 trouble of1 causes of1 #aia4 ,timers1 types of1 #ih4 ,timing magneto1 #ahe4 ,tires1 #agb4 cleaning of1 #bbb4 protection of1 #bbb4 reducing the cutting of1 #bbc4 unevenly worn1 cause of1 #bbh4 ,torsion rod1 necessity for1 #adh4 ,transmission1 parts of1 #aab4 ,trap on gasoline line1 #gc4 ,trembler 7see ,vibrator74 ,trouble1 air intake1 #aig4 battery1 causes of1 #ahb4 carburetor1 causes of1 #aie4 circulation connections1 #aii4 coil1 causes of1 #ahf4 compression1 causes of1 #aig4 cooling1 causes of1 #aii4 engine failing to deliver full power1 #bji4 engine failing to start1 #bjh4 engine missing at high speed1 #bac4 engine starting1 then stopping1 #bad4 engine stopping1 #baf4 freezing of water1 #bjj4 gasoline1 causes of1 #aic4 gasoline feed pipe1 causes of1 #aie4 igniter1 causes of1 #ahi1 #bhb4 ignition1 causes of1 #agi4 location of1 #bjc4 lubrication1 #bja4 magneto1 ,bosch1 #bif4 causes of1 #ahc1 #bfd1 #cjf4 ,eisemann1 #bie4 in general1 #bfd4 low tension1 #bha4 missing explosions1 #baa4 noises1 #bag4 overheating1 #bae4 piston ring1 #aih4 secondary distributer1 causes of1 #aib4 spark plug1 causes of1 #ahg4 switch1 causes of1 #aic4 tank1 causes of1 #aid4 timer1 causes of1 #aia4 weak explosions1 #baj4 ,two-cycle engine1 #dg1 action of1 #di4 advantages and disadvantages of1 #ej4 efficiency of1 #ea4 ,two-cylinder engine balance1 #ch4 ,two-cylinder vertical engine1 disadvantages of1 #db4 ,two-to-one gears1 #bh4 ,types of carburetors1 #eh4 of timers1 #ih4 ,universal joints1 action of1 #add4 necessity for1 #add4 ,use of antiskid devices1 #agd4 ,valve1 automatic1 #be4 action of1 #bf4 adjustment of1 #bce4 spring of1 #bg4 check and relief1 #fh4 grinding of1 #bbf4 leaking of1 effect of1 #bac4 lifter rod of1 #bh4 mechanically operated1 action of1 #bf4 parts of1 #be4 setting of1 #bcb4 spring of1 replacing of1 #bbg4 ,valves1 location of1 #bi4 necessity for1 #h4 ,vapor of gasoline1 #eb4 ,vehicle springs1 action of1 #age4 ,vibration absorbed by fly wheel1 #cg4 ,vibration of engines1 #cg4 ,vibrator1 #ajc4 ,vibrator1 adjustment of1 #bbi4 principle of1 #aje4 contacts of1 renewing of1 #ahf4 necessity for1 #ajb4 parts of1 #ajc4 slow1 effect of1 #bac4 ,vibrators1 mechanical and magnetic1 #ajc4 action of1 #ajc4 ,voltage of storage cell1 #hd4 ,volts1 #gg4 ,warning of overheating1 #baf4 ,washing the car1 #bba4 ,water1 cooling1 flow of1 #ca4 dirt in1 #aii4 forced circulation of1 #cb4 gravity system of1 #cd4 ,water cooling1 #ca4 ,water jackets1 #ca4 ,water pumps1 #cb4 ,wear of tires1 #agc4 ,weight of fly wheel1 #db4 ,winding of primary induction coil1 #ic4 of secondary induction coil1 #if4 ,wires1 broken1 #aha4 causes of breaking1 #ahj4 ,wiring1 #bcf4 for jump spark1 #bch4 for make-and-break1 #bdj4 ,wrist pin1 #bc4 ,,the ,,end ,a ,,motor-,,boat ,,story4 ,across ,europe in a ,motor-,boat4 ,by ,,henry ,c4 ,,rowland1 author of 8,in the ,shadow10 etc4 ,illustrated by upward of fifty sketches4 #abmo4 ,decorated cloth1 gilt top1 #b4jj net4 ,this is a delightful narrative of an absolutely unique trip4 ,mr4 ,rowland and his two friends had a motor-boat constructed in ,london for a seven-thousand-mile inland voyage which should circle ,europe by way of the ,seine1 the ,rhine1 the ,danube1 and the ,black ,sea4 ,the struggles with the motor1 which develops a degree of perversity almost human1 the innumerable humorous and exciting incidents1 and the final terrific adventure which ends the narrative with a shipwreck in the ,black ,sea1 make it the most novel and entertaining book of travel of recent years4 ,the talented author is well known through half a dozen books and many magazine stories4 ,the style of the volume is very attractive4 ,some fifty sketches are sprinkled through the text4 ,d4 ,,appleton ,,and ,,company1 ,,new ,,york4 ,,an ,,extraordinary ,,book4 ,the ,unofficial ,letters of an ,official's ,wife4 ,by ,,edith ,,moses4 #abmo4 ,cloth1 gilt top1 #a4ej net4 ,this is a volume of actual letters which ,mrs4 ,moses1 the wife of ,professor ,moses1 wrote from the ,philippines to her relatives here in the ,united ,states4 ,professor ,moses1 who is connected with the ,university of ,california1 was one of the five members of the first commission1 of which ,secretary ,taft was the head1 sent out by the ,u4 ,s4 ,government to organize the government of the ,philippine ,islands4 ,the members of this commission were practically the first important ,americans to go to the ,philippines in a peaceful and a civil capacity4 ,mrs4 ,moses1 therefore1 saw the social1 political1 and home life in ,manila as well as in the provinces and the different islands before ,american civilization had entered there to any extent4 ,her letters1 while descriptive1 have a very definite connection one with the other4 ,they describe the arrival at the ,philippines1 the beginning of life there1 housekeeping1 the seemingly strange methods of daily life1 servant problems1 and so on1 in ,manila4 ,nothing like these letters has appeared in regard to the ,philippine ,islands at any time4 ,it should be borne in mind1 furthermore1 that these letters are not in any way technical or having to do with the organization of the ,philippine government4 ,they are1 as the title suggests1 quite 8unofficial0 letters of a lady who1 because of her connection with official circles1 saw many things which an ordinary traveler never could see4 ,d4 ,,appleton ,,and ,,company1 ,,new ,,york4 ,transcriber's ,notes pg #ca ,changed3 thermo-siphon circulation to3 thermosiphon pg #adb ,changed3 there is less change to3 chance pg #age ,changed3 chains or other anti-skid to3 antiskid pg #bgb ,changed3 ,in multi-cylinder engines to3 multicylinder pg #bgb ,changed3 illustration text to3 ,make-and-,break pg #bhj ,changed3 period to comma after3 be brought into use pg #cbf ,added period after3 ,indicated by excessive heating pg #cbf ,added period after3 ,defective insulation pg #cbf ,added period after3 ,mixture ignites pg #cbf ,added period after3 ,faulty adjustment of float pg #cbf ,added period after3 ,seconday short circuit 7#a7 pg #cbf ,added period after3 should be from #a_/fd to #a_/acb inch pg #cbf ,changed3 ,dose cylinder with to3 ,douse pg #ccg ,changed3 ,thermo-siphon system to3 ,thermosiphon ,distributor and distributer both used in text4 ,many hyphenated and non-hyphenated word combinations left as written4