,transcriber's ,notes3 ,underscores 80 before and after a word or phrase indicate italics in the original text4 ,equal signs 80 before and after a word or phrase indicate bold in the original text4 ,small capitals have been converted to ,,solid capitals4 ,illustrations have been moved so they do not break up paragraphs4 ,typographical and punctuation errors have been silently corrected4 ,,tractor ,,principles ,,the ,,action1 ,,mechanism1 ,,handling1 ,,care1 ,,maintenance ,,and ,,repair ,,of ,,the ,,gas ,,engine ,,tractor ,,by ,,roger ,b4 ,,whitman ,,author ,,of 8,,motor ,,car ,,principles10 8,,gas ,,engine ,,principles10 8,,motor-,,cycle ,,principles10 ,,etc4 ,illustration ,,fully ,,illustrated ,d4 ,,appleton ,,and ,,company ,,new ,,york ,,london #aibj ,,copyright1 #aibj1 ,,by ,d4 ,,appleton ,,and ,,company ,,printed ,,in ,,the ,,united ,,states ,,of ,,america ,,foreword ,the tractor of to-day is built in almost as many types and designs as there are tractor makers1 and is far from being as standard as the automobile4 ,there are tractors with one driving wheel1 with two driving wheels1 with three and with four1 as well as three arrangements of the crawler principle2 there are two-wheelers1 three-wheelers and four-wheelers2 tractors that are controlled by pedals and levers and tractors that are driven by reins4 ,thus if a man who is competent to handle and care for one make is given another make to run1 he may be entirely at a loss as to how it works and how it should be handled4 ,it is the purpose of this book to explain and describe all of the mechanisms that are in common use in tractor construction1 to the end that the reader may be able to identify and understand the parts of whatever make he may see or handle4 ,,contents ,,page ,,chapter ,i ,,tractor ,,principles ,comparison between tractors and automobiles--,what is required for each--,advantage of understanding the mechanism--,no standard tractor design--,principal parts of a tractor--,necessity for each #a ,,chapter ,,ii ,,engine ,,principles ,power attained from heat--,combustible mixture--,principle of engine operation--,combustion space--,gas engine cycle--,dead strokes--,flywheel--,starting an engine--,inlet stroke--,compression stroke--,importance of compression--,ignition--,advance and retard of ignition--,power stroke--,exhaust stroke--,production of power--,vertical and horizontal engines--,firing order #i ,,chapter ,,iii ,,engine ,,parts ,base--,bearings--,cylinders--,crankshaf t--,piston--,connecting rod--,wrist pin--,piston rings--,valves--,cam--,valve mechanisms--,cooling system #cj ,,chapter ,,iv ,,fuels ,,and ,,carburetion ,oxygen necessary for combustion--,forming a mixture--,rich and poor mixtures--,carbon--,preignition-- ,carbureter--,spray nozzle--,evaporation of fuels--,carbureter principles-- ,extra air inlet--,effect of heat on mixture--,loading-- ,strangler #eb ,,chapter ,v ,,carbureters ,carbureter parts--,manifold--,action of carbureter--,float feed--,kerosene and gasoline--,descriptions of carbureters--,pump feed--,use of water in the mixture--,application of heat--,fuel pumps--,air cleaners--,governors #gj ,,chapter ,,vi ,,ignition ,principle of ignition--,point of ignition--,preignition--,advance and retard--,parts of ignition system--,magnetism--,induction--,magneto --,action of armature--,armature windings--,circuit breaker--,circuit--,shuttle and inductor armatures--,sparking current--,grounded circuit-- ,magneto parts--,impulse starter #ajb ,,chapter ,,vii ,,battery ,,ignition ,,systems ,principle of spark coil--,windings--,timer--,atwater-,kent system--,vibrator--,spark plugs #aca ,,chapter ,,viii ,,transmission ,transmission parts--,clutches--,necessity for change speed gear--,high and low gear--,types of change speed gears--,necessity for differential--,principle of differential--,drives--,worm #adc ,,chapter ,,ix ,,tractor ,,arrangement ,tractor requirements--,tractor types--,engine position-- ,front axles--,spring supports #afg ,,chapter ,x ,,lubrication ,importance of lubrication--,effect of oil--,kinds of oil--,effect of temperature on oil--,using the right kind of oil--,burning point--,viscosity--,lubrication charts--,oiling systems--,oil pumps--,mechanical oiler-- ,oil cup--,grease cup #age ,,chapter ,,xi ,,tractor ,,operation ,using a new tractor--,breaking in--,daily inspection--,driving--,shifting gears--,driving on hills--,using the engine as a brake--,cold weather conditions--,starting in cold weather--,protection against freezing--,starting a tractor #bja ,,chapter ,,xii ,,engine ,,maintenance ,fuel system and carbureter--,carbureter adjustment--,dirt in the fuel--,running on kerosene--,care--,magneto and ignition system--,care of magneto--,smoothing platinum points--,adjustment--,timing a magneto--,testing a magneto--,ignition trouble--,compression--,testing for compression leaks--,valve grinding--,valve timing--,carbon--,removing carbon #bac ,,chapter ,,xiii ,,locating ,,trouble ,engine will not start--,engine loses power--,engine stops--,engine misses--,engine starts2 but stops--,engine overheats--,engine smokes #bde ,,chapter ,,xiv ,,causes ,,of ,,trouble ,troubles and their causes in tabular form #bei ,,index #bfa ,,illustrations ,,fig4 ,,page #a ,the ,gas ,engine ,cycle #ae #b #a-;cylinder power diagram #ba #c #b-;cylinder power diagram #bb #d #b-;cylinder power diagram1 #ahj shaft #bd #e ,h4 ,d4 ,o4 power diagram #bf #f #d-;cylinder power diagram #bg #g #b-;cylinder crank shaft #ca #h #d-;cylinder crank shaft #cb #i ,half of a plain bearing #cb #aj ,connecting rod bearings #cc #aa ,piston complete and in section #cd #ab ,wrist pin fastenings #cf #ac ,valve #ch #ad ,action of cam #ci #ae 8,twin ,city0 tractor engine #da #af 8,hart-,parr0 valve mechanism #dc #ag 8,hart-,parr0 engine #de #ah 8,oil-,pull0 engine #dg #ai ,horizontal double opposed engine #di #bj 8,monarch0 engine #ea #ba ,principle of carburetor #ei #bb ,principle of extra air inlet #fd #bc 8,kingston0 carburetor1 model ,l #gb #bd 8,kingston0 carburetor1 model ,e #ge #be 8,kingston0 carburetor1 dual model #gg #bf 8,e-,b0 carburetor #gi #bg 8,e-,b0 carburetor1 side view #ha #bh ,pump-fed carburetor #hb #bi 8,titan0 carburetor #hd #cj ,pump-fed carburetor with two fuel nozzles #he #ca 8,hart-,parr0 mixture heater #hg #cb 8,twin ,city0 manifold #hh #cc ,fuel pump #ij #cd 8,avery0 fuel connections #ib #ce 8,oil-,pull0 fuel system #ic #cf ,air washer #ie #cg ,air strainer #if #ch 8,e-,b0 governor #ig #ci 8,case0 governor #ih #dj 8,hart-,parr0 governor #ii #da ,vertical governor #aja #db ,armature #ajg #dc ,flow of magnetism through armature core #ajh #dd ,one complete revolution of the armature #aaa #de ,connections of ,bosch magneto #aab #df 8,k-,w0 inductor #aae #dg 8,k-,w0 inductor in three positions #aag #dh 8,dixie0 inductor #aah #di ,three positions of 8,dixie0 inductor #abj #ej 8,bosch0 circuit breaker #aba #ea 8,k-,w0 circuit breaker #abb #eb 8,bosch0 magneto in section #abf #ec 8,k-,w0 magneto in section #abi #ed ,magnetism in a copper wire #acb #ee ,magnetism from electricity #acc #ef ,principle of spark coil #acd #eg 8,atwater-,kent0 ignition system #acf #eh ,vibrator coil ignition system #aci #ei ,spark plug #ada #fj ,internal clutch #add #fa ,plate clutch #adg #fb ,principle of sliding gear #aee #fc ,principle of jaw clutch change speed gear #aeg #fd 8,i4 ,h4 ,c40 chain drive1 showing differential #afb #fe 8,case0 rear axle #afc #ff 8,oil-,pull0 rear axle #afd #fg ,driving worm #afe #fh ,tractor arrangement #afh #fi ,tractor arrangement #afi #gj 8,gray0 tractor #aga #ga ,types of front axles #agb #gb ,spring support #agc #gc 8,mogul0 oiling diagram #ahj #gd 8,illinois0 oiling diagram #ahc #ge ,end of 8,twin ,city0 connecting rod #ahe #gf ,wrist pin lubrication #ahf #gg ,force feed oiling system of 8,gray0 engine #ahg #gh ,oil pump #ahh #gi 8,e-,b0 oil pump #ahi #hj ,oil pump with hollow plunger #aij #ha ,methods of preventing oil leaks #aia #hb 8,titan0 lubricator #aib #hc 8,i4 ,h4 ,c40 method of oiling crank pins #aic #hd 8,hart-,parr0 oiling system #aid #he ,oil cup #aie #hf ,proper use of a grease cup #aif #hg 8,titan0 #aj-bj oiling diagram #aih #hh 8,international0 oiling diagram #aii #hi ,grinding valve in engine with fixed head #bca #ij ,grinding valve in detachable head #bcc #ia ,grinding valve in detachable seat #bcd #ib ,valve seat cutter #bce #ic 8,holt0 valve arrangement #bcf #id ,valve timing1 using marks on flywheel #bch #ie ,valve timing #bci ,,tractor ,,principles ,,chapter ,i ,,tractor ,,principles ,while tractors and automobiles are the same in general principles1 there is a wide difference between them in design1 construction1 and handling1 due to the differences in the work that they do and in the conditions under which they do it4 ,an automobile is required to move only itself and the load that it carries4 ,while it can run over rough roads1 these must be hard enough to support it2 on soft ground it will sink in and be unable to get itself out4 ,it can make great speed over smooth1 level roads2 but only rarely do road and police conditions permit it to run its fastest for more than a few minutes at a time4 ,for the greater part of its life it develops only a portion of the power of which it is capable4 ,a tractor1 on the other hand1 is intended not to carry1 but to haul4 ,it must run and do its work on rough hillsides1 soft bottoms1 or any other land where it is required to go4 ,instead of developing speed it develops pulling power1 and must be able to develop its full power continuously4 ,appearance and comfort count for a great deal in an automobile1 and much attention is devoted to making it noiseless and simple to manage4 ,these things do not apply in a tractor1 which is a labor-saving and money-making machine1 valuable only for the work that it can do4 ,there is no question of upholstery or nickel-plating2 all that is wanted is a machine that will do the required work with the least possible cost of operation4 ,as is the case with any kind of machine that is purchased as a money-maker1 its cost should be as low as is consistent with its ability to do its work4 ,any extra cost for accessories1 or finish1 or other detail1 is wasted unless it permits the machine to do more work1 or1 by making the operator more comfortable1 allows him to run the machine for a longer stretch of time or with greater efficiency4 ,it may be taken for granted that any tractor will run and will do its work with satisfaction1 provided it is sensibly handled and cared for4 ,far more troubles and breakdowns come from careless handling and from neglect than from faulty design and material4 ,a tractor that is running and doing its work is earning a return on the money invested in it2 when it is laid up for repairs there is not only a loss of interest on the investment1 but a loss of the value of the work that it might be doing4 ,to keep a tractor running is a matter only of understanding and of common sense2 common sense to realize that any piece of machinery needs some degree of care and attention1 and understanding of where the care and attention should be applied4 ,the more thoroughly a tractor operator understands his machine1 the more work he will be able to get out of it1 and the more continuously it will run4 ,this is only another way of saying that understanding and knowledge pay a direct return in work done and money earned4 ,in the early days of the automobile there were as many types of cars as there were manufacturers4 ,as time has gone on1 the unsatisfactory ideas have been weeded out1 and automobiles have approached what may be called a standard design4 ,at the present time1 tractor designs are varied1 and it is hardly possible to speak of any type as standard4 ,the reason for this lies in the fact that many manufacturers start with a design for one special part1 and build the tractor around it4 ,for example1 a manufacturer may develop a method of driving the wheels that he feels is especially good for tractor work4 ,in applying it he may find that the engine must be so placed on the frame that when the power pulley is in position the belt will interfere with the front wheels unless they are small2 he therefore uses small front wheels1 and advocates them for tractors4 ,another manufacturer with a patent steering gear may be able to place the power pulley so that there is ample clearance for the belt2 he finds that by using high front wheels he can get a better support for the frame1 and therefore claims that high front wheels are an advantage4 ,other designs may be based on having three wheels1 or two2 advantages are claimed for each type1 and each type undoubtedly has them4 ,the selection of a tractor is based on one's own experience or on that of neighbors1 or on the ability of the salesman to bring out the advantages of the make that he sells2 but when the tractor is bought and delivered1 its ability to do the work promised for it depends solely on the care with which it is handled and looked after4 ,whatever the design of a tractor may be1 there are certain parts that it must have in order to do the work required of it4 ,these parts1 or groups of parts1 are as follows3 ,engine4--,this furnishes the power by which the tractor operates4 ,clutch4--,by means of a clutch the engine may be connected with the mechanism1 so that the tractor moves1 or it may be disconnected1 so that it may run without moving the tractor4 ,change ,speed ,gear4--,as will be explained in later chapters1 an engine1 in order to work most efficiently1 should run at a fixed speed2 the tractor should be able to run fast or slow1 according to conditions4 ,a change speed gear is therefore provided1 by which the speed of the tractor may be changed1 although there is no change in the speed of the engine4 ,drive4--,the drive is the mechanism that applies the power of the engine to the wheels1 and makes them turn4 ,differential4--,when a tractor makes a turn1 the outside wheels cover a larger circle than the inside wheels1 and therefore must run faster in order to get around in the same time4 ,it is usually the case that the power of the engine is applied to both driving wheels2 if both were solid on the axle1 like the wheels of a railroad car1 one would be forced to slip when making a turn1 which would waste power4 ,by applying a differential1 the engine can drive both wheels1 but the wheels may run at different speeds when conditions require it4 ,the clutch1 change speed gear1 drive and differential form the transmission4 ,steering gear4--,by means of the steering gear the direction in which the tractor moves may be changed4 ,supports4--,a tractor moves on broad-tired wheels1 or on crawlers1 which are so formed that they grip the ground and do not slip4 ,they give so broad a support that even on soft ground the weight of the tractor will not pack the soil sufficiently to injure it as a seed bed4 ,frame4--,the frame is the foundation of the tractor1 and holds the parts in the proper relation to each other4 ,it is usually made of channel steel1 the parts being bolted to it2 in some tractors1 however1 the parts are so attached to each other that they form their own support1 and no other frame is needed4 ,tractor manufacturers make these parts in different ways2 all accomplish the same result1 but do it by different methods4 ,the main principles are much the same1 and should be known and understood4 ,they are described and explained in the succeeding chapters4 ,,chapter ,,ii ,,engine ,,principles ,the working part of a tractor is the engine2 it is this that furnishes the power that makes the machine go4 ,the engine gets its power from the burning of a mixture of fuel vapor and air4 ,when this mixture burns1 it becomes heated1 and1 as is usual with hot things1 it tries to expand1 or to occupy more room4 ,the mixture is placed in a cylinder1 between the closed end and the piston2 it is then heated by being burned1 and1 in struggling to expand1 it forces the piston to slide down the cylinder4 ,this movement of the piston makes the crank shaft revolve1 which in turn drives the tractor4 ,the first step in making the engine run is to put a charge of mixture into the cylinder1 and it is clear that if the burning of the charge is to move the piston1 the piston must be in such a position that it is able to move4 ,when the mixture is burned1 the piston must therefore be at the closed end of the cylinder4 ,after the charge of mixture has been burned1 the cylinder must be cleared of the dead and useless gases that remain1 in order to make room for a fresh charge4 ,the charge of mixture is drawn into the cylinder just as a pump sucks in water4 ,at a time when the piston is at the closed end of the cylinder1 a valve is opened connecting the space above the piston with the device that forms the mixture2 then by moving the piston outward1 mixture is sucked into the space above it4 ,when the piston reaches the end of its stroke the cylinder has been filled with mixture1 and the valve then closes4 ,it would be useless to set fire to the mixture at that time1 for the piston is as far down the cylinder as it can be1 and pressure could not move it any farther4 ,to get the piston into such a position that the expanding mixture can move it1 it is forced back to the closed end of the cylinder4 ,this squeezes or compresses1 the cylinderful of mixture into the small space1 called the combustion chamber1 between the piston and the cylinder head4 ,if the mixture is now burned1 the piston can move the length of the cylinder1 and in so doing it develops power4 ,the cylinder is cleared of the burned and useless gases by opening a valve and pushing them out by moving the piston back to the inner end of the cylinder4 ,when this has been done1 the valve is closed1 and1 by opening the inlet valve and moving the piston outward1 a fresh charge is sucked in1 and the several steps of the gas engine cycle are repeated4 ,the name cycle is given to any series of steps or events that must be gone through in order that a thing may happen4 ,thus the empty shell must be taken out of a gun and a fresh cartridge put in before the gun can be fired again1 and that series of steps might be called the gun cycle4 ,the gas engine cycle requires the piston to make four strokes4 ,an outward stroke sucks in a charge of mixture1 and an inward stroke returns the piston to the firing position and compresses the charge4 ,then comes the outward stroke when the piston moves under power1 followed by the inward stroke that clears the cylinder of the burned gases4 ,for every stroke of the piston the crank shaft makes a half-revolution2 the crank shaft therefore makes two revolutions to four strokes of the piston and to each repetition of the gas engine cycle4 ,of these four strokes of the piston only one produces power4 ,the other three strokes1 called the dead strokes1 are required to prepare for another power stroke4 ,a gas engine cylinder thus produces power for only one quarter of the time that it runs4 ,this is one of the striking differences between the gas engine and the steam engine1 for the piston of a steam engine moves under power all of the time that the engine runs4 ,a one-cylinder gas engine must have something to make the piston go through the dead strokes1 for otherwise the piston would stop at the end of the power stroke2 the piston is kept in motion by heavy flywheels attached to the crank shaft4 ,these1 like any object1 try to continue in motion when once they are started2 a power stroke starts the crank shaft revolving and its flywheels keep it going4 ,thus1 the piston drives the crank shaft during the power stroke1 and the crank shaft drives the piston during the dead strokes4 ,to start an engine1 the crank shaft is revolved to make the piston suck in a charge of mixture and compress it2 then the charge is burned1 the power stroke takes place1 and the engine runs4 ,a clear idea of what goes on inside of the cylinder is quite necessary in order to take proper care of an engine and to get the best work out of it4 ,the following description applies to any cylinder1 for the action in all cylinders of an engine is the same4 ,inlet ,stroke4--,during the inlet stroke 7,no4 #a1 ,fig4 #a71 the piston moves outward2 the inlet valve is open1 and the exhaust valve is closed4 ,this movement of the piston creates suction1 and if there are leaks in the cylinder1 air will be sucked in and will spoil the proportions of the charge4 ,this will prevent the proper burning of the mixture1 and the engine will lose power4 ,the piston moves at such high speed that the mixture cannot enter fast enough to keep up with it2 mixture is still flowing in when the piston reaches the end of its stroke1 and even when it begins to move inward on the next stroke4 ,the more mixture there is in the cylinder1 the more powerfully the engine will run2 the inlet valve is therefore held open for as long a time as the mixture continues to enter4 ,illustration ,illustration3 ,,fig4 #a4--,,the ,,gas ,,engine ,,cycle ,in slow-speed #a-;cylinder and #b-;cylinder engines the valve closes when the piston reaches the end of its stroke2 on high-speed engines the valve does not close until the piston has moved inch or inch on the compression stroke4 ,compression ,stroke4--,during the compression stroke 7,no4 #b1 ,fig4 #a7 the piston moves inward1 and both valves are closed4 ,this movement places the piston in position to move outward on the power stroke4 ,as the outlets to the cylinder are closed1 the charge of mixture cannot escape1 and is therefore compressed into the space between the piston and the cylinder head when the piston is at the inner end of its stroke4 ,this space is usually about one quarter the volume of the cylinder2 the charge is therefore compressed to about one quarter of its original volume4 ,this compression of the charge is very important in the operation of the gas engine1 and any interference with it will make the engine run poorly4 ,in the first place1 it improves the quality of the charge1 and makes it burn very much better4 ,when the charge enters the cylinder1 the fuel vapor and air are not thoroughly mixed2 much of the fuel is not turned into vapor4 ,by compressing the charge it becomes heated2 this vaporizes the fuel1 and vapor and air become thoroughly mixed4 ,compression also increases the power4 ,suppose that the cylinder contains a quart of mixture which1 when heated1 will expand to a gallon4 ,if this quart of mixture is compressed to a half pint1 it will not lose its ability to expand to a gallon1 and will exert more pressure in expanding from a half pint to a gallon than from a quart to a gallon4 ,a leaky cylinder will cause a further loss of power because some of the charge will escape during the compression stroke1 which will leave less to be burned and to develop power4 ,ignition4--,setting fire to the charge of mixture is called the ignition of the charge1 and it takes place close to the end of the compression stroke4 ,to get the greatest power1 all of the mixture should be on fire and heated most intensely as the piston begins the power stroke4 ,when the mixture is set on fire1 it does not explode like gunpowder1 but burns comparatively slowly2 the charge is ignited by an electric spark1 and the flame spreads from that point until it is all on fire4 ,in order to give the flame time to spread1 the spark passes sufficiently before the end of the compression stroke to have the entire charge on fire as the power stroke begins4 ,this is called the advance of the ignition4 ,the flame takes the same time to spread through the charge when the engine is running fast as when it is running slow4 ,therefore if the engine is speeded up1 the spark must be advanced1 for otherwise the piston would be on the power stroke before the flame would have time to spread all through the mixture4 ,when the engine is slowed down1 the spark must have less advance1 or must be retarded1 for1 if it were not1 the charge would all be in flame1 and exerting its full pressure1 before the piston reached the end of its compression stroke4 ,the subject of ignition1 which is of great importance1 is covered more fully in ,chapter ,,vi4 ,power ,stroke4--,during the power stroke 7,no4 #c1 ,fig4 #a7 the piston moves outward1 and both valves are closed4 ,as it begins1 the mixture is all on fire1 and great pressure is exerted against the piston4 ,as the piston moves outward the combustion space becomes larger1 and the gases obtain the room for expansion that they seek4 ,as they expand1 the pressure that they exert becomes less4 ,by the time the piston is three quarters the way down the power stroke1 the pressure is so reduced that it has little or no effect2 the gases are still trying to expand1 however1 so the exhaust valve is opened at that point1 and they begin to escape4 ,exhaust ,stroke4--,during the exhaust stroke 7,no4 #d1 ,fig4 #a7 the piston moves inward and the exhaust valve is open4 ,this movement of the piston pushes the burned gases out of the cylinder1 and it is clear that the more thoroughly the cylinder is emptied of them1 the more room there will be for a fresh charge4 ,in high-speed engines the gases cannot escape as fast as the piston moves2 they are still flowing out when the end of the stroke is reached4 ,therefore the valve is closed1 not at the end of the stroke1 but when the piston has moved about inch outward on the inlet stroke4 ,the inlet valve opens as the exhaust valve closes4 ,it can be seen that through the inlet and compression strokes a leak will reduce the charge and so interfere with the production of full power4 ,the piston must make a tight fit in the cylinder1 the valves must seat tightly1 and gaskets and other parts must be in proper condition4 ,illustration3 ,,fig4 #b4--a-;,,cylinder ,,power ,,diagram ,figure #b shows a power diagram for a #a-;cylinder engine1 in which the crank shaft moves under power during one stroke out of every four4 ,an engine with two cylinders can be built so that first one cylinder applies power and then the other1 in which case the crank shaft moves under power during two strokes out of every four4 ,illustration3 ,,fig4 #c4--b-;,,cylinder ,,power ,,diagram ,figure #c is a power diagram of an engine of this sort4 ,if piston #a is moving down under power1 piston #b is also moving down1 but on the inlet stroke4 ,the following stroke is exhaust in cylinder #a and compression in cylinder #b1 and cylinder #b will then deliver a power stroke while cylinder #a is on inlet4 ,thus the crank shaft will receive a power stroke1 followed by a dead stroke2 then another power stroke and another dead stroke1 and so on4 ,there will be the disadvantage1 however1 that the pistons1 moving up and down together1 will cause vibration1 which in the course of time will be likely to give trouble4 ,to overcome this1 a #b-;cylinder engine can be built as indicated in ,figure #d4 ,in this engine the cranks project on opposite sides of the crank shaft instead of on the same side1 as in ,figure #c2 the pistons thus move in opposite directions1 and produce no vibration4 ,power will be unevenly applied1 however1 for both power strokes occur in one revolution1 with two dead strokes in the succeeding revolution4 ,illustration ,illustration3 ,,fig4 #d4--b-;,,cylinder ,,power ,,diagram1 #ahj ,,shaft ,with piston #a moving down on power1 piston #b1 moving upward1 can only be performing compression or exhaust4 ,if it is on compression1 its power stroke will follow the power stroke of piston #a1 while if it is on exhaust its power stroke will have occurred immediately before the power stroke of piston #a4 ,in either case one power stroke follows the other1 taking place in one revolution of the crank shaft1 while in the following revolution both pistons will be performing dead strokes4 ,while there is no vibration from the movement of the pistons in this engine1 the uneven production of power will produce vibration of another kind4 ,these two types may be built with the cylinders standing up or lying down2 that is1 they may be either vertical engines or horizontal engines4 ,the double opposed engine1 which is built only in horizontal form1 is free from either kind of vibration1 but has the disadvantage of occupying more room than the others4 ,the cylinders1 instead of being side by side1 and on the same side of the crank shaft1 are placed end to end1 with the crank shaft between them1 as shown in ,figure #e4 ,the pistons make their inward and outward strokes together1 but in so doing they move in opposite directions4 ,thus every power stroke is followed by a dead stroke1 as in the engine shown in ,figure #c1 while the movement of one piston balances that of the other1 as is the case with the engine shown in ,figure #d4 ,illustration3 ,,fig4 #e4--;,h4 ,d4 ,o4 ,,power ,,diagram ,illustration ,illustration3 ,,fig4 #f4--d-;,,cylinder ,,power ,,diagram ,in a #d-;cylinder engine one power stroke follows another without any dead stroke intervals1 which1 of course1 makes the crank shaft revolve more smoothly and with a steadier application of power4 ,the power diagram is shown in ,figure #f2 in studying this it should be remembered that if two pistons move in opposite directions1 as in ,figure #d1 one power stroke follows another1 while if they move in the same direction1 as in ,figure #c1 there is an interval of one stroke between their power strokes4 ,the crank shaft of a #d-;cylinder engine is so made that the middle pistons move in the same direction1 and opposite to the end pistons4 ,this construction has been found to make a smoother running engine than if pistons #a and #c moved one way while pistons #b and #d moved the other4 ,if piston #a is on the power stroke1 either piston #b or piston #c can follow1 for they are moving in the opposite direction4 ,if we say that piston #b is the next1 then piston #d must be the third to give a power stroke1 for it is the only one left that is moving in the opposite direction to piston #b4 ,piston #c is thus the fourth to move under power1 and it is followed by another power stroke by piston #a2 the firing order is then said to be #a1 #b1 #d1 #c4 ,if it is piston #c that follows piston #a1 piston #d will again be the third to produce power1 and piston #b will be the fourth4 ,the firing order will then be #a1 #c1 #d1 #b4 ,there is no other order in which a #d-;cylinder engine can produce power1 and there is no choice between them4 ,the firing order of an engine is established by the manufacturer1 and depends on the order in which the valves are operated4 ,,chapter ,,iii ,,engine ,,parts ,the foundation of an engine is the base1 which supports the bearings in which the crank shaft revolves1 and to which the cylinders are attached4 ,the cylinders of tractor engines are made of cast-iron1 and the cylinder heads1 which close the upper ends of the cylinders1 are usually in a separate piece1 bolted on4 ,the joint between the cylinders and the cylinder head is made tight by placing between them a gasket of asbestos and thin sheet metal4 ,the crank shaft has as many cranks1 or throws1 as the engine has cylinders4 ,crank shafts for #b-;cylinder engines are shown in ,figure #g2 the upper one is for an engine of the type shown in ,figure #c1 with pistons moving in the same direction4 ,with both cranks projecting from one side the shaft is out of balance1 so balance weights are attached to the opposite side4 ,illustration3 ,,fig4 #g4--b-;,,cylinder ,,crank ,,shaft ,the other shaft shown in ,figure #g does not need balance weights1 for one crank balances the other4 ,a four-cylinder crank shaft1 ,figure #h1 is also in balance4 ,illustration3 ,,fig4 #h4--d-;,,cylinder ,,crank ,,shaft ,illustration3 ,,fig4 #i4--;,,half ,,of ,a ,,plain ,,bearing ,crank shafts revolve in main bearings1 which are set in the engine base4 ,in tractor engines these are usually plain bearings1 a half of such a bearing being shown in ,figure #i4 ,this is a bronze shell lined with a softer metal1 making an exact fit on the shaft2 with the two halves in place1 the shaft should turn freely1 but without looseness or side play4 ,the grooves shown are to admit lubricating oil4 ,illustration3 ,,fig4 #aj4--;,,connecting ,,rod ,,bearings ,illustration3 ,,fig4 #aa4--,,piston ,,complete ,,and ,,in ,,section ,the piston is attached to the crank shaft by a connecting rod1 which is illustrated in ,figure #aj4 ,pistons are shown in ,figures #aa and #ab2 they are made as light as is consistent with the pressure that they must bear1 and are hollow1 and open at the lower end4 ,the piston is attached to the connecting rod by a wrist pin1 or piston pin1 which is a shaft passing through it from side to side1 and also through the bearing in the upper end of the connecting rod4 ,the connecting rod swings on the wrist pin in following the rotation of the crank shaft1 and its attachment to the wrist pin must permit this without being loose4 ,the bearings at the two ends of a connecting rod are usually adjustable1 so that wear can be taken up2 some of the methods of doing this are illustrated in ,figure #aj4 ,in ,a1 the wrist pin bearing is a plain tube1 ground to an exact fit2 when it is worn it must be replaced4 ,in ,b1 the bearing is split1 and the ends are drawn together by a bolt to the correct fit4 ,the bearing in ,c is in two parts1 held together by a ,u-shaped bolt1 while in ,d the two parts are held together by a cap bolted to the end of the connecting rod4 ,in ,e1 the end of the connecting rod is a square loop enclosing the two parts of the bearing2 the parts are held in the proper position by a wedge adjusted by screws4 ,the crank shaft bearing of the connecting rod shown in ,f is in two parts which are hinged together4 ,g1 ,h1 and ,k show the forms usually used in tractor engines1 which consist of two parts bolted together4 ,illustration3 ,,fig4 #ab4--,,wrist ,,pin ,,fastenings ,the wrist pin is usually firmly attached to the piston1 so that the connecting rod swings on it2 methods of securing the wrist pin are shown in ,figure #ab1 the wrist pin being held in supports cast in the piston4 ,in ,a1 the wrist pin is held by two set screws1 and in ,b1 by pins passing through it4 ,the wrist pin shown in ,d is hollow1 as is very common1 and a bolt passes through part of the piston and into the wrist pin4 ,in the construction shown in ,c the wrist pin is secured to the connecting rod and moves in bearings in the piston4 ,in ,e1 a ring fitting in a groove around the piston prevents the wrist pin from moving endways4 ,the engine must usually be taken to pieces in order to get at the wrist pin2 lock nuts1 lock washers or cotter pins are always used to prevent the trouble that would be caused if the wrist pin worked loose4 ,a leak-proof joint between the piston and the cylinder is made by means of piston rings that fit in grooves around the piston1 as shown in ,e1 ,figure #ab4 ,piston ring grooves are shown in ,figure #aa4 ,piston rings are not solid1 but are split so that they are elastic2 they fit snugly in their grooves1 and tend to spring open to a greater size than the cylinder4 ,this causes them to maintain a close fit against the cylinder1 and the gases are prevented from leaking past4 ,illustration3 ,,fig4 #ac4--,,valve ,each cylinder is provided with two valves3 the inlet valve that admits fresh mixture and the exhaust valve through which the burned gases escape4 ,these valves are metal disks with funnel-shaped edges fitting into funnel holes4 ,a valve and its stem are shown in ,figure #ac and also in ,figure #ae4 ,illustration3 ,,fig4 #ad4--;,,action ,,of ,a ,,cam ,a valve is opened at the proper time by a cam1 and closed by a spring4 ,a cam is a wheel with a bulge on one side1 so that its rim is eccentric to its shaft1 as illustrated in ,figure #ad1 which shows a cam in three positions of a revolution4 ,a rod resting on the rim of the cam is moved endways as the bulge passes under it1 and the valve is operated by connecting it with the rod4 ,a valve is opened once during two revolutions of the crank shaft2 therefore the cam cannot be placed on the crank shaft1 for1 if it were1 the valve would be opened every revolution4 ,the cam is placed on a separate shaft which is driven by the crank shaft at half its speed4 ,this is usually done with gears1 a gear on the crank shaft meshing with a gear on the cam shaft having twice as many teeth2 the crank shaft gear must make two revolutions in turning the cam shaft gear once4 ,the valve in ,figure #ac is held on its seat by a spring4 ,the cam bears against the end of the valve stem1 and as it revolves its bulge forces the valve stem and valve to move endways and thus to uncover the valve opening4 ,as the movement of the piston depends on the crank shaft1 the valve can be made to open at the right time by a proper setting of the gears that drive the cam shaft4 ,the length of time that the cam will hold the valve open depends on the shape of the bulge of the cam4 ,it can be seen that the pointed cam of ,figure #ac will not hold the valve open for as long a time as the flat-end cam of ,figure #ad4 ,illustration3 ,,fig4 #ae4--8,,twin ,,city0 ,,tractor ,,engine ,in the design shown in ,figure #ac the cam bears directly against the end of the valve stem1 the cam shaft in this case lying along the cylinder head4 ,in the construction shown in ,figure #ae the valves are not placed in the cylinder head1 but are in an extension or valve pocket projecting from the combustion chamber2 this cam shaft is near the crank shaft4 ,it would not be practicable to make the valve stem long enough to reach down to the cam1 so a length of rod1 called a push rod1 or tappet1 is placed between them2 the cam moves the push rod and the push rod in turn moves the valve4 ,this is a construction frequently used for automobile engines4 ,illustration3 ,,fig4 #af4--8;,,hart-,,parr0 ,,valve ,,mechanism ,in tractor engines the cam shaft is usually placed near the crank shaft1 as in ,figure #ae1 and the valves are in the head1 so that a valve moves in the opposite direction to the movement of the push rod4 ,this requires still another part to be used1 called the rocker arm4 ,it is shown in ,figure #af4 ,it is a short bar1 pivoted at or near the center1 with one end at the push rod and the other at the valve stem4 ,when it is moved by the push rod it in turn moves the valve4 ,valves operated by push rods and rocker arms are also shown in ,figures #ag1 #ah and #ai2 ,figure #ah is a single-cylinder horizontal engine1 while ,figure #ai is a horizontal double opposed engine1 in which one cam operates a valve in each cylinder4 ,figure #bj shows the valve mechanism of a vertical engine in which all parts1 including the rocker arm1 are enclosed to protect them from dust1 and so they can run in oil4 ,a small space is always left somewhere between the cam and the valve stem1 to give the valve stem room to lengthen1 which it will do when it gets hot4 ,if this space were not left1 the valve stem1 in lengthening as it became hot1 would strike the part next to it1 and the valve would be lifted from its seat4 ,this would cause the engine to lose power4 ,this space must be kept properly adjusted1 and instructions for this will be found in ,chapter ,,xii4 ,illustration3 ,,fig4 #ag4--8;,,hart-,,parr0 ,,engine ,a valve is held against its seat by a spring1 which must be compressed when the valve is opened4 ,if this spring is too weak1 it will not hold the valve tightly on its seat1 while if it is too stiff1 the cam shaft and other parts will be needlessly strained in compressing it4 ,friction between the cam and the end of the valve stem or push rod would cause rapid wear if these parts were not of hardened steel1 and kept well oiled4 ,still further to reduce wear1 there is usually a roller on the end of the push rod1 as shown in ,figure #af and some of the other illustrations4 ,figure #ae shows a construction in which the end of the push rod is a flat disk1 which rotates as the cam comes into contact with it4 ,illustration3 ,,fig4 #ah4--8,,oil-,,pull0 ,,engine ,when the mixture burns1 the top of the piston1 the cylinder head1 and the walls of the combustion chamber become heated1 and if it is not prevented they will get so hot that they will expand sufficiently to cause the piston to stick1 or seize4 ,the upper part of the cylinder is1 therefore1 provided with a cooling system that keeps these parts from getting overheated4 ,channels are provided through which water is circulated2 the water takes the heat from the metal parts1 becoming heated itself1 and then passes to a cooler1 or radiator1 where it gives up the heat to currents of air4 ,in addition to the channels1 or water jackets1 around the cylinder1 a cooling system includes the radiator1 the connections1 and usually a pump that keeps the water in motion4 ,illustration3 ,,fig4 #ai4--;,,horizontal ,,double ,,opposed ,,engine ,in some tractors1 notably the ,fordson1 no pump is used2 the water circulates because it is heated4 ,this is called a thermo-syphon system4 ,when the engine runs1 the water in the cylinder jackets becomes heated2 as hot water is lighter than cold water1 it rises and flows out of the jackets to the radiator1 its place being taken by cool water from the bottom of the radiator4 ,this circulation continues as long as the water in one part of the system is hotter than the water in some other part of the system4 ,the lubrication of an engine is described and explained in ,chapter ,x4 ,illustration3 ,,fig4 #bj4--8,,monarch0 ,,engine ,,chapter ,,iv ,,fuels ,,and ,,carburetion ,in order that a thing may burn1 it must be provided with oxygen4 ,oxygen is found in air1 so it is usual to say that air is necessary in order that anything may burn4 ,to prove this1 light a candle and place an empty bottle over it1 upside down2 in a very short time the oxygen in the bottle will be used up1 and the flame will flicker and get smoky1 and finally die out4 ,if a card is laid on the chimney of a coal-oil lamp so that it covers the opening1 that flame also will flicker1 get smoky and go out4 ,in order to deaden the fire in a stove1 the dampers are closed to prevent air from entering2 the fire is kept alight by the very small quantity of air that leaks in below the fire-box4 ,when the drafts are opened the fire will burn up brightly because a plentiful volume of air can then enter4 ,in a similar way1 air must be used in a gas engine in order that the fuel may burn4 ,it is not possible to mix air with a liquid2 the first step in making a gas that will burn is1 therefore1 to turn the fuel1 whether it is gasoline1 kerosene1 distillate1 or other oil1 into a vapor2 this vapor is then mixed with air4 ,for good results it is very necessary that the vapor and air be in proper proportions4 ,in the experiment with the candle and the bottle it was seen that as the air was used up1 the candle flame became yellow and smoky3 this is the effect of insufficient air4 ,if there is not enough air in the mixture1 part of the vapor will not be able to burn1 and will only smoke4 ,if1 on the other hand1 there is too much air1 the mixture1 if it will burn at all1 will burn slowly1 and the extra volume of air will reduce the heat4 ,in a mixture of the proper proportions of air and fuel vapor1 the burning1 or combustion1 will be very rapid1 resulting in the sudden production of the greatest possible amount of heat4 ,this1 of course1 is what is necessary if the engine is to produce its fullest power4 ,with such a mixture1 combustion will be complete before the piston has done more than start outward on the power stroke1 and the greatest possible1 or maximum1 pressure will then be produced4 ,when a mixture burns slowly1 the piston will have gone through much of the power stroke before combustion is complete1 in which case a considerable part of the pressure that should have been applied at the beginning of the stroke will be wasted4 ,a mixture that is not correct will burn unevenly2 it may burn better during one power stroke than during another1 which will make the engine run unsteadily4 ,if the mixture has too much air in proportion to the amount of vapor1 it is known as a thin mixture1 or a lean or poor mixture4 ,it burns so slowly that it is quite possible for the mixture that started burning before the beginning of the power stroke to continue burning through the exhaust stroke1 and for enough flame to remain in the cylinder to set fire to the fresh charge that enters during the next inlet stroke4 ,this will produce what is known as a backfire2 that is1 the mixture entering the cylinder will catch fire1 and in burning will blow back through the open inlet valve4 ,this is a dangerous condition1 for the flame might spread to fuel dripping from the carburetor1 or to the fuel tank4 ,a mixture that has not enough air is called a rich mixture2 the air that is present will burn part of the vapor1 while the rest will go out of the exhaust unburned1 or will work past the piston into the oil in the crank case4 ,this is wasteful of fuel4 ,the most serious result of a rich mixture1 however1 is in the production of carbon1 and the carbonization of the engine4 ,the flame of a rich mixture is smoky2 the smoke of this flame1 as is the case with smoke from all other sources1 is composed of fine particles of carbon1 or soot4 ,these particles of carbon will deposit on all parts of the combustion space3 on the top of the piston1 on the valves1 on the spark plugs1 and on the inner wall of the cylinder head4 ,at first it is gummy1 but it rapidly hardens and forms a crust that must be scraped off with a steel tool4 ,carbon in an engine will reduce the power through causing preignition1 or1 in other words1 by setting fire to the fresh charge before the proper point in the stroke4 ,the heat of the combustion will cause the carbon deposit to become so heated that it will glow1 these glowing particles being sufficient to ignite the incoming fresh charge4 ,the remedy for this condition is to remove the carbon1 which is usually done by taking off the cylinder head and scraping away the deposit4 ,it may be added that carbon is also formed by the use of too much lubricating oil1 as will be explained in the chapter on lubrication4 ,thus it is seen that if the engine is to run properly1 and is to be kept in good condition1 the proportions of the mixture must be very carefully maintained4 ,the mixture is formed in a carburetor1 or mixer4 ,this is1 roughly1 in the form of a tube through which air is sucked during the inlet stroke2 projecting into it is a fine tube called a spray nozzle through which the fuel enters4 ,in action it is somewhat similar to the atomizer that is used for spraying the nose and throat4 ,by forcing the fuel to flow rapidly through this small tube it comes out in the form of spray1 and the tiny drops are picked up by the current of air and are carried into the cylinder4 ,it is much easier to form a mixture of gasoline than of kerosene or distillate1 because gasoline vaporizes more readily at ordinary temperatures4 ,if saucers of gasoline and kerosene are placed in the sun1 the gasoline will evaporate rapidly and completely1 leaving only a faint oily deposit4 ,the kerosene1 on the other hand1 will evaporate slowly1 and much of it will not evaporate at all4 ,to make kerosene and distillate evaporate completely1 they must be heated1 just as water must be heated to make it evaporate4 ,in the case of a carburetor for gasoline1 the current of air needs only to be warmed2 the spray of gasoline will evaporate on coming into contact with the warmed air1 and much of it will enter the cylinder as vapor4 ,in order to evaporate kerosene and distillate much more heat must be provided1 and it is usually considered necessary to heat not only the current of air1 but the liquid fuel as well4 ,methods of doing this will be explained in the next chapter4 ,illustration ,illustration3 ,,fig4 #ba4--,,principle ,,of ,,carburetor ,when kerosene or distillate is used1 there are conditions that make it necessary to add water vapor to the mixture1 which prevents the overheating of the cylinder and reduces the deposit of carbon4 ,the difficulty of making a complete vapor of kerosene and distillate results in a tendency on the part of these fuels to carbonize the cylinders2 the use of water aids in keeping the cylinders clean4 ,the general principle of a carburetor is shown in ,figure #ba1 one drawing illustrating conditions when the inlet valve is closed and the other when it is open4 ,it shows an engine cylinder connected with an inlet pipe or mixing chamber1 through which there is a swift flow of air during an inlet stroke4 ,projecting into the intake pipe is the spray nozzle1 which is connected with a small chamber containing fuel2 inside of this chamber is a float1 usually made of cork1 although it is sometimes a light metal box4 ,the fuel is intended to fill the chamber to a certain height1 at which the valve will be closed by the float rising on the fuel4 ,this level is such that the fuel does not quite reach the tip of the spray nozzle4 ,during the compression1 power1 and exhaust strokes1 the fuel stands at this level1 for it cannot run out of the spray nozzle1 and the float holds the valve closed4 ,as soon as the inlet valve opens1 air rushes through the intake pipe and sucks fuel out of the spray nozzle4 ,this1 of course1 takes fuel out of the float chamber2 the float in sinking opens the valve1 and enough fuel enters to restore the level4 ,the fuel comes out of the nozzle in the form of fine spray2 it is in such small drops that it evaporates quickly1 and the resulting mixture of fuel vapor and air passes into the cylinder4 ,by using a spray nozzle of the proper size1 any desired proportion of fuel and air may be obtained4 ,if an engine runs at a single speed1 a carburetor as simple as this one would be satisfactory1 for if the suction is always the same1 there will be little or no change in the proportions of the mixture that is formed4 ,to get the best results1 the proportions of fuel vapor and air should be the same for all running speeds of the engine4 ,the proportions of the mixture1 however1 depend on the violence of the suction1 which changes as the engine speed changes1 becoming greater as the speed increases4 ,the simple carburetor illustrated in ,figure #ba can be adjusted to give a correct mixture for any particular speed1 but will be out of adjustment for any other speed4 ,the speed of a #a-;cylinder engine does not change very greatly2 it is built to run at practically a constant speed1 and a simple carburetor is satisfactory for it4 ,the speed of engines with a greater number of cylinders may be greatly changed1 and the carburetor must be so made that it will give the same proportions of vapor and air at low speed as at high4 ,in the simple carburetor described1 the speeding-up of the engine will result in a greater rush of air through the intake pipe1 which in turn will suck out a much greater quantity of fuel4 ,if the carburetor is adjusted to give the proper quantity of fuel for the air that passes at low speed1 at high speed it will give far more fuel than will be required by the quantity of air that then passes4 ,thus at high speed the mixture will be too rich4 ,if1 on the other hand1 this carburetor is adjusted to give a proper mixture at high speed1 too little fuel will be sucked out when the engine runs slowly1 and the mixture will be too lean4 ,a carburetor must thus have an additional device that will keep the mixture correct1 regardless of the speed at which the engine runs4 ,this is sometimes done by changing the size of the spray nozzle so that a greater or less quantity of fuel flows out1 but more usually by permitting an extra quantity of air to enter the carburetor as the engine speeds up4 ,this is done with an extra air intake1 the principle of which is illustrated in ,figure #bb4 ,as will be seen1 this carburetor has two openings for air1 one being the main air inlet and the other the extra air inlet4 ,the latter is an opening provided with a valve which is held on its seat by a spring4 ,the suction created by an inlet stroke is exerted in the carburetor1 but at low speed is not sufficient to suck the extra air valve from its seat4 ,air then enters only through the main air inlet1 and the spray nozzle is adjusted to give the proper proportion of fuel4 ,illustration3 ,,fig4 #bb4--,,principle ,,of ,,extra ,,air ,,inlet ,as the engine speed increases the mixture becomes richer2 but there is also an increase in suction1 which becomes strong enough to pull the extra air valve from its seat4 ,this provides another opening into the carburetor1 through which enough air enters to keep the mixture in proper proportion4 ,the higher the speed of the engine the more the valve will open1 and the greater will be the quantity of air admitted4 ,in order to get the fullest power from an engine1 the carburetor is built to give its most perfect mixture at the usual working speed4 ,this will be the speed at which the engine will run under ordinary conditions4 ,as the engine will run at this speed most of the time1 the carburetor should then deliver its best mixture on the least possible quantity of fuel4 ,as an engine is run at low speed so little of the time1 it is not necessary that the mixture should then be so perfect or that the fuel should be used so economically4 ,the design of a carburetor is a complicated matter1 because the production of mixture is due to the flow of air1 which is a very changeable thing4 ,on a cold1 damp day1 the air will be heavier and denser than on a day that is hot and dry1 and different quantities of fuel will be necessary for the formation of the mixture4 ,the carburetor manufacturer cannot make a commercial carburetor that will take care of such a difference as this2 he strikes an average that gives good general results1 and expects the user to change the adjustments when weather and temperature make it necessary4 ,the formation of the mixture is affected by the condition of the engine4 ,when all of the parts of the engine are tight1 the suction in the carburetor is more violent than when there is a leakage of air past the piston rings1 or through a leaky valve or spark plug4 ,on a dry1 hot day the fuel evaporates much more readily than on a day that is cold and damp2 more of the fuel that flows out of the spray nozzle will be vaporized and the formation of the mixture will be easier4 ,on a cold1 damp day the fuel will not vaporize in the carburetor to any extent1 and much of it will pass to the cylinder in drops that even there will not vaporize in time to form a mixture4 ,in order to assure the vaporization of enough fuel to form a mixture under such conditions1 the fuel and the air must be heated to a greater degree4 ,as the engine becomes heated up1 more and more of the fuel will vaporize1 and the amount flowing out of the spray nozzle may therefore be cut down4 ,with fuels like kerosene and distillate1 which do not vaporize as readily as gasoline1 it is not unusual to have them condense on the walls of the inlet pipe1 which produces a condition known as loading4 ,this condensation is similar to the sweating of an ice-water pitcher on a hot day4 ,if an engine is running at a constant speed1 loading does not make much difference1 because the carburetor is so adjusted that it gives a proper mixture4 ,if the engine is suddenly speeded up1 however1 the greater rush of air will pick up the condensed fuel1 and the mixture will instantly become too rich1 continuing so until this extra supply of fuel is used up4 ,the result will be to choke the engine and make it lose power just at the time when extra power is needed4 ,loading can be prevented by heating the inlet pipe to such an extent that the fuel will not condense on it4 ,the speed of a tractor engine is practically always controlled by a throttle1 which is a valve set in the passage of the carburetor4 ,it operates exactly the same as a damper in a stovepipe2 when it is closed1 it shuts the passage and prevents the flow of mixture to the engine4 ,as it is opened1 it permits a greater quantity of mixture to flow1 and it follows1 of course1 that as the charges of mixture become larger1 the engine runs with more power4 ,a tractor carburetor usually has two throttles1 one being operated by hand and the other by the governor4 ,it is usual for a carburetor to be fitted with a strangler1 or choke1 which makes it easier to form a mixture at slow starting speed4 ,when an engine is cold1 the fuel evaporates slowly2 and1 furthermore1 when an engine is cranked by hand its speed is so low that the suction in the carburetor is not sufficient to draw out enough fuel to form a mixture4 ,the strangler is a valve similar in every way to the throttle1 but placed between the main air inlet and the spray nozzle4 ,when it is closed and the engine is cranked1 very little air can enter the carburetor2 the suction is therefore very great4 ,far more fuel than usual is then sucked out of the spray nozzle1 and of this greater amount enough reaches the cylinder to form a combustible mixture4 ,the engine will start1 but as soon as it does so1 the strangler must be opened so that the normal amount of air enters4 ,if this is not done1 the excessive suction will draw so much fuel out of the spray nozzle that the mixture formed will be too rich to burn4 ,,chapter ,v ,,carburetors ,the apparatus that forms the mixture is in two parts1 one being the carburetor that proportions the fuel to the quantity of air drawn into the cylinder1 and the other the mixing chamber1 or manifold1 that connects the carburetor with the valve chamber4 ,the mixing chamber has no adjustments2 it is a passage1 often a pipe1 that is shaped to fit the conditions1 and according to the ideas of the manufacturer4 ,when kerosene and distillate are used1 the mixing chamber must be heated1 so it is frequently built into the exhaust manifold1 which is the pipe that conducts the burned gases away from the engine4 ,in some cases it gets heat from the water jacket of the engine1 a water jacket formed around it being connected with the cooling system4 ,the carburetor1 on the other hand1 has adjustments that must be understood in order to run the engine economically4 ,the understanding of these adjustments is simplified if it is remembered that the object of the carburetor is to maintain a correct proportion of fuel to the volume of air that passes through it4 ,all tractor carburetors operate on the same principles1 and the principles are applied in much the same way4 ,if these principles are understood1 and there is an understanding of what the parts of a carburetor are for and what they do1 there should be no difficulty in adjusting and caring for any kind of a carburetor that may be offered4 ,the main body of the carburetor is the tube through which the air passes4 ,this is a casting1 and cannot be adjusted or altered4 ,into this passage projects the spray nozzle1 which is usually provided with an adjustment to control the amount of liquid that may flow out of it4 ,when no adjustment is provided1 the spray nozzle is made removable1 so that a nozzle with an opening of any desired size may be inserted4 ,illustration3 ,,fig4 #bc4--8,,kingston0 ,,carburetor1 ,,model ,l ,on some carburetors the extra air valve is set by the manufacturers1 while on others it is adjustable by controlling the strength of the spring that holds it against its seat4 ,the carburetor shown in ,figure #bc has a spray nozzle adjustment of a very usual type4 ,a rod is so arranged that its pointed end projects into the opening of the spray nozzle2 by screwing it up or down the opening may be made larger or smaller1 so that more or less fuel may flow out4 ,the extra air valve is a flap valve that closes the air passage until the suction is great enough to lift it from its seat4 ,around the spray nozzle is a tube that connects the passage below the extra air valve with the passage above it2 when the suction is too low to lift the extra air valve from its seat1 any air flowing through the carburetor passes through this tube4 ,the tube is so small that even a little air passing through it is enough to suck fuel out of the spray nozzle1 and the spray nozzle is so adjusted that enough fuel comes out to make a proper mixture with that volume of air4 ,this is the low-speed adjustment1 which gives a mixture on which the engine will start and will run at its lowest or idling speed4 ,at this speed the engine produces just enough power to keep itself going4 ,when the engine speeds up1 and suction increases1 the extra air valve is lifted off its seat1 and a greater volume of air flows through the carburetor4 ,the increased suction also draws more fuel out of the spray nozzle4 ,if the greater amount of fuel were in proportion to the greater volume of air1 there would be no change in the mixture1 but this is not the case4 ,as suction increases1 the proportion of fuel drawn out of the spray nozzle becomes too great for the air1 and the mixture becomes too rich4 ,to overcome this1 the extra air valve permits a still greater volume of air to pass1 so that the proportions of fuel and air do not change4 ,the chamber below the air passage in ,figure #bb is the fuel cup1 into which fuel flows from the tank4 ,inside the fuel cup is a ring of cork attached to a pivoted lever1 on the other end of which is a needle valve that can close the opening through which the fuel enters the cup4 ,as the cup fills1 the cork floats on it1 and in rising it moves the lever on its pivot4 ,when the fuel reaches such a level that it is near the tip of the spray nozzle1 the valve closes the opening and prevents more fuel from entering4 ,illustration3 ,,fig4 #bd4--8,,kingston0 ,,carburetor1 ,,model ,e ,in the carburetor shown in ,figure #bd1 the principal air passage is past the spray nozzle1 and all air goes by this passage when the engine is running at low speed4 ,the extra air inlet consists of a number of holes through which air can pass without going past the spray nozzle4 ,on each of these holes is a ball2 when the suction is low the balls completely close the holes4 ,when speed increases1 the suction becomes great enough to lift the balls off the holes1 and the extra volume of air that is necessary is permitted to enter4 ,by making the balls of different weights1 it can be seen that the volume of air admitted for any speed is under good control4 ,like the carburetor shown in ,figure #bc1 this carburetor is of the float feed type2 that is1 the flow of fuel to it is controlled by a valve that is operated by a float4 ,either of these two carburetors may be adjusted for gasoline or for kerosene1 but the adjustment that is right for one is wrong for the other4 ,thus1 if an engine is started on gasoline1 with the intention of running on kerosene1 the carburetor must be readjusted when the change is made4 ,this is unsatisfactory1 so a double carburetor is sometimes used1 as shown in ,figure #be4 ,this consists of two carburetors of the kind shown in ,figure #bd1 having a single mixture outlet1 one being adjusted for gasoline and the other for kerosene4 ,either of them can be connected with the mixture outlet by means of a switch valve4 ,illustration3 ,,fig4 #be4--8,,kingston0 ,,carburetor1 ,,dual ,,model ,in order to run on kerosene or distillate it is necessary to apply heat for the reason that these oils do not evaporate readily at ordinary temperatures4 ,gasoline1 on the other hand1 evaporates readily1 and a cold engine can be started on it4 ,tractors that run on kerosene or distillate are therefore started on gasoline and run on it until they are hot enough to vaporize the heavier oil4 ,a carburetor that will run on either gasoline or kerosene is shown in ,figure #bf4 ,the main air inlet is at ,e1 which leads the air around the spray nozzle and into the chamber ,g4 ,the mixture flows to the cylinder by the passage ,b4 ,the control of the fuel at working speeds is by the high-speed adjustment1 which is a needle valve screwing into the spray nozzle4 ,above this is another needle valve that adjusts the flow of fuel for slow speed4 ,extra air enters through the opening ,a1 which is closed at slow speed by a valve held against it by a spring4 ,this valve bears against one end of a pivoted lever1 the other end of which is attached to the slow-speed needle valve2 when the extra air valve opens it moves the lever and the slow-speed needle valve is lifted to permit the flow of a greater volume of fuel from the spray nozzle4 ,illustration3 ,,fig4 #bf4--8;,e-,b0 ,,carburetor ,this carburetor is started on gasoline4 ,when the engine is hot1 a switch valve is operated to permit the burned gases from the engine to flow through the carburetor2 they pass through the pipe ,c1 ,d1 and as the chamber ,g is directly in their path it becomes intensely heated4 ,the carburetor can then be switched to kerosene4 ,a side view of this carburetor is shown in ,figure #bg4 ,these carburetors are all of the float feed type1 and are used on engines of which the speed is variable4 ,a carburetor that is fed by a pump is shown in ,figure #bh4 ,this is a simple tube with a fuel cup cast on one side of it4 ,fuel is pumped to the bowl1 and the proper level is maintained by an overflow through which excess fuel passes back to the tank4 ,this carburetor is intended for an engine of which the speed does not change greatly4 ,its only adjustment is the spray nozzle1 and this is altered to correspond with changes in engine speed4 ,illustration3 ,,fig4 #bg4--8;,e-,b0 ,,carburetor1 ,,side ,,view ,illustration3 ,,fig4 #bh4--,,pump-,,fed ,,carburetor ,if an engine is clean and in good condition1 it will run as well on kerosene as on gasoline1 although the heating effect of kerosene is greater4 ,when an engine is carbonized1 as is usually the case1 a condition known as preignition will occur unless it is prevented4 ,carbon from unburned fuel or from lubricating oil will deposit on the piston head and the parts of the combustion chamber1 and particles will become heated to the glowing point1 when they will set fire to the fresh mixture during the compression stroke and before the proper time4 ,the effect is to make the engine lose power1 and it also gives rise to a sharp metallic knocking4 ,by reducing the temperature in the cylinder during the compression stroke this condition can be prevented4 ,this can be done by adding water vapor to the mixture1 and kerosene carburetors are therefore built with a water attachment4 ,as can be seen in ,figure #bh1 this is a water cup and spray nozzle like those for the fuel4 ,when the engine knocks1 and shows that preignition is occurring1 water is turned on1 and1 being carried into the cylinder1 keeps the mixture from being heated to the point of ignition before the proper time4 ,figure #bi shows the attachment of this carburetor to an engine which1 in this case1 is horizontal4 ,to start the engine1 gasoline is injected into the carburetor1 as shown2 this will give a sufficiently good mixture for the purpose1 and enough heat for running on kerosene is thus obtained4 ,illustration3 ,,fig4 #bi4--8,,titan0 ,,carburetor ,illustration3 ,,fig4 #cj4--,,pump-,,fed ,,carburetor ,,with ,,two ,,fuel ,,nozzles ,the carburetor shown in ,figure #cj is similar1 but has a bowl and spray nozzle for gasoline1 to use in starting4 ,it is also provided with a heating jacket through which hot water or hot gases may circulate4 ,in many cases the fuel is heated before reaching the carburetor4 ,this is done by coiling the feed pipe around the exhaust pipe or putting it in a jacket through which hot water circulates4 ,another device sends the mixture through a chamber heated by the exhaust1 as shown in ,figure #ca4 ,figure #cb shows an arrangement in which the mixture passes through a jacket around one branch of the exhaust pipe4 ,by means of a switch valve1 ,a1 more or less of the exhaust gases may be permitted to flow through this branch1 so that the mixture may be heated to any desired degree4 ,illustration ,illustration3 ,,fig4 #ca4--8;,,hart-,,parr0 ,,mixture ,,heater ,all of these heating devices are so arranged that the heat is under the control of the driver1 which permits him to heat the mixture as much as he judges to be necessary4 ,enough heat must be used to prevent the fuel from condensing2 but too much heat will cut down the efficiency of the engine because it will cause so much expansion of the mixture that a cylinderful of it will not produce the maximum power4 ,illustration3 ,,fig4 #cb4--8,,twin ,,city0 ,,manifold ,figure #cc shows the pump that is used in a force feed carburetor of the type shown in ,figure #bh4 ,its plunger is forced through an inward stroke by a cam1 and makes an outward stroke as its spring returns it to position4 ,the inlet and outlet openings of the cylinder are closed by ball check valves1 the inlet check being open on the outward strokes1 and the outlet check being open on the inward strokes4 ,a pump of this sort requires no attention beyond seeing that the check valves work properly1 and that there are no leaks4 ,figure #cd shows the connections between the fuel tank and the carburetor4 ,under the tank1 #a1 is a chamber containing a fine wire strainer1 #d1 through which the fuel must pass to reach the carburetor2 any dirt that may be present is strained out1 and collects in the cup1 #b4 ,water in the fuel also settles here1 and the cup is cleaned out by unscrewing the plug1 #c4 #e is the shut-off cock2 it should always be closed when the tractor is not working4 ,illustration3 ,,fig4 #cc4--;,,fuel ,,pump ,a complete fuel system is illustrated in ,figure #ce1 showing the connections of the tanks1 pumps1 and carburetor4 ,as dirt is injurious to an engine1 the air that forms the mixture must be clean1 so when a tractor works in a dusty field1 it should be equipped with an air cleaner1 of which there are three kinds4 ,in one of these the air is required to pass through water1 which washes it4 ,a cleaner of this type is shown in ,figure #cf4 ,the dusty air enters the central passage1 and is forced to pass through the water in order to reach the outlet4 ,passage through the water and through the baffle plates frees the air of all its dust4 ,in the cleaner shown in ,figure #cg1 the air is passed through loose wool1 which filters out the dust4 ,another type of cleaner works on the same principle as a cream separator2 the air is given a whirling motion1 which throws the dirt out at the sides1 and it is collected in a glass jar4 ,illustration3 ,,fig4 #cd4--8;,,avery0 ,,fuel ,,connections ,illustration3 ,,fig4 #ce4--8,,oil-,,pull0 ,,fuel ,,system ,these air cleaners must be emptied frequently1 for if they are not kept clean it cannot be expected that they will do their work4 ,a tractor engine is built to develop its maximum power at a certain speed2 if it runs at greater speed1 it will not operate efficiently1 and there will be unnecessary wear of its parts4 ,these engines are therefore usually fitted with governors which hold them at their most efficient speed4 ,a governor operates by centrifugal force4 ,anything in motion tries to move in a straight line2 if it is forced to move in a circle1 it will exert force in trying to move away from its center4 ,it is this that is called centrifugal force4 ,it is centrifugal force that holds water in a pail that is being swung around the head1 and that makes the pail fly off if it is released4 ,illustration3 ,,fig4 #cf4--;,,air ,,washer ,in applying this principle to a governor1 weights are attached to a plate and made to revolve2 springs hold them together1 but in spite of this1 centrifugal force throws them outward4 ,in moving1 they act on a rod that operates the throttle2 as the speed increases1 the move outward more and more1 and it is a simple matter of adjustment to cause them to close the throttle when the speed reaches a desired point4 ,illustration3 ,,fig4 #cg4--;,,air ,,strainer ,illustration3 ,,fig4 #ch4--8;,e-,b0 ,,governor ,a governor and its connections are shown in ,figure #ch4 ,the weights1 ,r1 are ,l-shaped1 and pivoted at the angle to a plate driven by the engine4 ,the shaft that drives the plate also supports a collar1 ,p1 that is loose on it and can slide endways2 the collar rests against the short bar of the ,l-shaped weights4 ,the other end of the collar touches the lever1 ,e1 which is moved when the collar moves4 ,as the lever is connected with the throttle1 a movement of the collar will control the position of the throttle4 ,illustration3 ,,fig4 #ci4--8;,,case0 ,,governor ,when the shaft revolves1 the long arms of the ,l-shaped weights tend to fly outward2 this moves them on their pivots1 and the short arms thereupon force the collar to slide on the shaft1 which moves the lever and operates the throttle4 ,the speed at which the throttle will begin to close is determined by the setting of the spring that holds the weights in4 ,illustration3 ,,fig4 #dj4--8;,,hart-,,parr0 ,,governor ,governors and governor connections are shown in ,figures #ci and #dj4 ,the governor shown in ,figure #da is enclosed in a housing that can be locked or sealed4 ,this prevents the unauthorized changing of the adjustment4 ,illustration3 ,,fig4 #da4--,,vertical ,,governor ,,chapter ,,vi ,,ignition ,in order that a gas engine may run properly1 the mixture must be set on fire1 or ignited1 at exactly the right time2 if ignition occurs too early or too late1 there will be a loss of power4 ,the greatest pressure will be obtained at the instant when all of the mixture is burning1 and this should take place just as the piston begins to move outward on the power stroke4 ,a little time is required for the mixture to burn2 there is a brief interval between the instant when it is set on fire and the instant when it is all in flame4 ,thus it is clear that if the mixture is all to be burning as the piston starts the power stroke1 it must be set on fire before that time1 or1 in other words1 toward the end of the compression stroke4 ,the point at which ignition should occur depends on the speed of the engine and should change when the speed changes4 ,the time required for the flame to spread throughout the mixture does not change2 let us say that1 with the engine running at #abjj revolutions a minute1 the mixture can be ignited when the piston is inch from the end of the compression stroke1 and will all be in flame by the time the piston starts on the power stroke4 ,if the engine is slowed down to #fjj revolutions a minute and no change is made in the ignition1 the mixture will all be in flame before the piston reaches the end of the compression stroke2 pressure will then be produced before the piston is in position to perform the power stroke4 ,the pressure will try to make the engine run backwards2 it will sometimes be sufficient to make the engine stop4 ,if the momentum of the flywheel is sufficient to force the piston to the end of the stroke against the pressure1 this condition will cause a loss of power4 ,this is called preignition1 or ignition that occurs too soon4 ,one effect of it is to produce a hard1 metallic knocking1 due to the oil being squeezed out of the bearings by the great pressure1 which permits the bearing and shaft to strike4 ,the remedy is to make ignition occur later in the stroke4 ,if the engine is speeded up above #abjj revolutions1 the piston will have had time to move some distance on the power stroke before the mixture is all in flame2 the combustion space will then be too large to permit the mixture to produce its greatest pressure1 and again there will be a loss of power4 ,the remedy in this case is to make ignition occur earlier in the compression stroke4 ,when ignition is made to occur early in the compression stroke1 it is said to be advanced2 when it is made to occur late in the stroke1 it is said to be retarded4 ,to get the best results1 the engine should be run with ignition advanced as far as is possible without causing knocking4 ,the charge of mixture is always set on fire by an electric spark1 and the parts that produce and control this spark are called the ignition system4 ,an ignition system consists of3 ,first1 the apparatus that produces the electric current1 which is usually a magneto2 second1 a timer1 which controls the instant at which the spark occurs2 third1 the spark plugs1 which project into the cylinders1 and at which the sparks take place2 fourth1 a switch1 by which the sparking current can be turned on or off1 and fifth1 the wires1 or cables1 by which the parts are connected4 ,the electric current that gives the spark is always produced by magnetism4 ,in a magneto1 magnetism is obtained from the heavy steel magnets that are part of it2 there is a constant flow of magnetism from one end of these to the other4 ,to obtain an electric current1 a coil of wire is placed in the magnetism1 and the strength of the magnetism is made to change2 it alternately becomes weak and strong4 ,whenever a change in strength takes place1 an electric current flows in the wire1 and it continues to flow as long as the magnetism continues to change in strength4 ,when the change in strength is very great1 that is1 when the magnetism changes from very weak to very strong1 or from very strong to very weak1 the electric current is more powerful than when there is only a little change in strength4 ,a more powerful current is also produced by a change that takes place suddenly than by a change that takes place slowly4 ,the electrical principle that produces a current in this manner is called induction2 the current produced is known as an induced current4 ,a magneto has two or more magnets1 and between their ends1 or poles1 there revolves a piece of iron called the armature4 ,a piece of iron placed between the poles of a magnet becomes a magnet itself2 the armature is so shaped that1 as it revolves1 its magnetism continually changes in strength1 and it is the changes in the strength of the magnetism of the armature that produce the sparking current4 ,illustration3 ,,fig4 #db4--;,,armature ,the iron armature of the ,bosch magneto1 which is the best known type1 is shown in ,figure #db4 ,it has a central bar with two heads1 the wire being wound around the central bar1 or core4 ,the shafts on which it revolves are attached to the ends of the heads4 ,figure #dc shows different positions of the armature between the poles of the magnet1 and illustrates the changes in the magnetism of the central bar4 ,there is a continual flow of magnetism from one pole of a magnet to the other2 if a piece of iron lies between them the magnetism will use it as a bridge1 but often its easiest path will be through the air4 ,in ,a1 ,figure #dc1 the armature lies crossways1 and its central bar or core forms a perfect bridge for the magnetism4 ,practically all of the magnetism flows through it1 and it then becomes a powerful magnet itself4 ,it sets up its own flow of magnetism1 which flows through the core to one head1 through the air to the other head1 and so back to the core4 ,illustration3 ,,fig4 #dc4--;,,flow ,,of ,,magnetism ,,through ,,armature ,,core ,in ,b1 the armature has revolved a little4 ,most of the magnetism is still flowing through the core1 but some of it is finding an easier path by flowing through the heads and across the air space to the other pole4 ,the magnetism of the core is1 therefore1 a little weaker than it is in ,a4 ,in ,c1 the heads alone form bridges between the poles1 and none of the magnetism flows by the core because that no longer forms a path4 ,the core is no longer producing magnetism2 in moving from ,a to ,c there has thus been a complete change in the strength of the magnetism of the core1 for from full strength it has died away to nothing4 ,by a further movement1 as in ,d1 the core again acts as a bridge1 and another change in strength occurs1 this time from nothing to full strength again4 ,in moving from ,d to ,b1 there are slight changes in strength1 but not enough to produce a sparking current2 it is only in passing from ,b to ,d that a sparking current can be produced4 ,in this type of magneto the space between the heads is wound full of wire1 which of course revolves with the armature2 the more turns of wire there are1 the more intense will be the current1 so very fine wire is used to get the greatest possible number of turns4 ,in the ,bosch magneto the first few layers are of coarse wire1 and are the primary winding4 ,the remainder1 called the secondary winding1 is very fine wire1 and the two are connected so that one forms an extension of the other4 ,it has been explained that it is most important to have the spark occur at exactly the right instant in the stroke4 ,on a magneto the instant of sparking is controlled by a timer1 or circuit breaker1 which is a switch that is automatically operated at the time when the magneto is producing a current sufficiently intense to form a spark4 ,figure #dd illustrates one complete revolution of the armature1 and it will be seen that it passes twice from position ,b to position ,d4 ,this shows that it gives a sparking current twice during each revolution4 ,the circuit breaker must therefore operate twice during each revolution4 ,it is placed at the end of the magneto2 in some makes it revolves with the armature and is operated by stationary cams1 while in others it is stationary1 and is operated by a cam on the armature shaft4 ,in either case the effect is the same4 ,illustration3 ,,fig4 #dd4--,,one ,,complete ,,revolution ,,of ,,the ,,armature ,illustration3 ,,fig4 #de4--;,,connections ,,of ,,bosch ,,magneto ,figure #de shows the way in which the winding on the armature of a ,bosch magneto is connected with the circuit breaker and with the armature4 ,the circuit breaker shown is not the kind used on the ,bosch1 and serves only to illustrate the principle4 ,it consists of a lever pivoted at one end1 with the other end resting against the tip of a screw4 ,a cam bears against the lever and can move it to break the contact with the screw4 ,the cam is so set that it moves the lever at the time when the current is most intense4 ,the coarse wire1 or primary winding1 on the armature is connected with the lever and with the screw of the circuit breaker2 when the lever is touching the screw1 any current produced in the primary winding has a complete path1 or circuit1 in which to flow4 ,the fine wire1 or secondary winding1 is wound on top of the primary1 and its inmost end is connected to the outmost end of the primary so that one forms a continuation of the other4 ,the outmost end of the secondary leads to the spark plug2 any current produced in the secondary winding flows to the spark plug1 and1 if intense enough1 will jump across the small gap in the plug1 and return to the secondary by way of the primary4 ,referring to ,figure #dc1 a weak current is produced in the primary while the armature revolves from ,d to ,b2 at that time the circuit breaker is closed1 so the current can flow in the path thus provided for it4 ,a current also tries to flow in the secondary1 but is too weak to jump across the gap in the spark plug4 ,as the armature comes closer to the point ,c1 ,figure #dc1 the primary current becomes more intense1 and the electricity in the secondary increases its endeavor to jump the gap in the spark plug1 but is still unable to do so4 ,as the armature passes over the point ,c1 the circuit breaker opens4 ,the primary current1 which is then most intense1 finds its path taken away from it1 and it seeks another1 which it finds by flowing into the secondary winding4 ,this flow of primary current1 added to the pressure already existing in the secondary1 forms a current sufficiently intense to jump across the gap in the spark plug1 and in so jumping it produces the ignition spark4 ,as the armature passes to position ,d1 ,figure #dc1 the circuit breaker closes1 and the action is repeated4 ,illustration3 ,,fig4 #df4--8,k-,w0 ,,inductor ,a magneto of this type is thus seen to give two sparks to every revolution of the armature4 ,k-,w and ,dixie magnetos operate on the same general principle as the ,bosch1 with the difference that the wire windings are separate from the armature1 and do not revolve4 ,the revolving part1 which is called an inductor1 consists of blocks of iron1 so shaped that1 as they revolve1 they alternately lead the magnetism to the core of the winding and then away from it4 ,the result is that the core gains magnetism and then loses it1 and these continual changes in strength produce sparking currents in the winding4 ,the inductor of a ,k-,w magneto is shown in ,figure #df4 ,it consists of a shaft on which are mounted two blocks of iron at right angles4 ,the section of shaft that joins them is the core of the winding2 the wire is wound on it just as thread is wound on a spool1 but with a space between1 so that the shaft may revolve inside of the coil4 ,figure #dg shows the inductor in three positions of its revolution between the poles of the magnet4 ,when it is in the first position1 magnetism can flow from one pole of the magnet to the other by going into one end1 ,a1 of one block1 through the core1 and out of one end1 ,c1 of the other block4 ,this makes a magnet of the core and it forms magnetism of its own4 ,when the inductor turns to the second position magnetism can get across without flowing through the core1 for the blocks now give it a path4 ,as the flow through the core ceases1 the core's magnetism dies away1 which gives the change in strength that is needed to produce a sparking current4 ,illustration3 ,,fig4 #dg4--8,k-,w0 ,,inductor ,,in ,,three ,,positions ,when the inductor is in the third position1 the core again becomes the path for the magnetism and is magnetized2 these changes continue as long as the inductor turns4 ,illustration3 ,,fig4 #dh4--8;,,dixie0 ,,inductor ,while an armature type of magneto1 like the ,bosch1 produces two sparks to every revolution1 the ,k-,w produces four1 for there are four periods during every revolution when there is sufficient change in the strength of the magnetism of the core to produce a sparking current4 ,in these magnetos the revolving shaft is parallel to the ends of the magnets1 but in the ,dixie magneto it is at a right angle1 as shown in ,figure #dh4 ,the shaft is of some metal1 such as brass or bronze1 through which magnetism will not flow2 otherwise the shaft would form a continuous path4 ,the inductor blocks are mounted on the shaft1 and act as extensions of the poles of the magnet4 ,the core on which the wire is wound is a separate piece1 placed under the arch of the magnets1 with ends that extend down and form a tunnel in which the inductor revolves4 ,figure #di shows an end view of the inductor1 the magnets being cut away so that the core may be seen4 ,as inductor block ,a is an extension of one pole of the magnet1 magnetism tries to flow from it to block ,b1 which is an extension of the other pole of the magnet4 ,when the inductor is in position #a1 ,figure #di1 magnetism can flow from block ,a through the core to block ,b1 the core then being magnetized4 ,in position #b1 magnetism can flow from one block to the other by going through the ends of the core instead of through the core itself2 the core then loses its magnetism1 but regains it when the inductor moves to position #c4 ,illustration3 ,,fig4 #di4--,,three ,,positions ,,of 8,,dixie0 ,,inductor ,in practically all makes of magnetos the circuit breaker is at the end of the armature or inductor shaft1 and is operated by it4 ,the ,bosch circuit breaker is illustrated in ,figure #ej1 the parts being mounted on a plate attached to the shaft and revolving with it4 ,the lever is ,l-shaped1 pivoted at the angle1 with one end resting on the tip of a screw4 ,when the shaft revolves1 the other end of the lever is dragged over a block of metal that acts as a cam2 this makes it move on its pivot and separates it from the screw4 ,by turning the screw the distance of separation may be adjusted4 ,illustration3 ,,fig4 #ej4--8;,,bosch0 ,,circuit ,,breaker ,in the circuit breaker of the ,k-,w magneto it is the cam that revolves1 while the lever is stationary1 as shown in ,figure #ea4 ,it will be noticed that the cam will move the lever only twice during each revolution2 the magneto can produce four sparks during a revolution1 but with this arrangement of the cam only two of them are used4 ,illustration3 ,,fig4 #ea4--8,k-,w0 ,,circuit ,,breaker ,it has been said that an intense sparking current is produced when there is a great change in the strength of the magnetism1 and when the change in strength occurs suddenly4 ,there cannot be any alteration in the change in strength1 for the greatest magnetic strength of the core is what is given it by the magnet1 and changing from this to nothing is the greatest change possible4 ,the suddenness with which the change takes place1 however1 depends on the speed at which the magneto runs4 ,a #d-;cylinder engine requires two sparks to each revolution of the crank shaft2 the armature of a ,bosch magneto for this engine will therefore run at the same speed as the crank shaft4 ,the ,k-,w magneto1 giving four sparks to the revolution1 could run at half of the speed of the crank shaft1 but then the change in the strength of the magnetism would take place slowly1 and the sparking current would not be sufficiently intense4 ,by using only two of the sparks the magneto is run at the same speed as the crank shaft2 the change in strength then takes place more suddenly1 and a more intense sparking current is produced4 ,the circuit breaker of a magneto for a #a-;cylinder engine has only one cam1 so that a single spark is produced during each revolution of the armature2 the armature makes one revolution to every two revolutions of the crank shaft4 ,however many cylinders an engine may have1 the magneto must be revolved from one point of sparking to the next in the interval between ignition in one cylinder and ignition in the next cylinder to fire4 ,a magneto is driven by the crank shaft through gears or by a chain1 which are so proportioned and set that the magneto is at a point of sparking at the instant when a piston is in position for ignition4 ,a magneto for an engine with more than one cylinder is provided with a distributor1 which passes the sparking current to the particular cylinder that is ready for ignition4 ,a distributor is a revolving switch built into the magneto1 with as many points1 or contacts1 as the engine has cylinders4 ,at the instant when the magneto produces a sparking current1 the revolving distributor arm is in position to pass the current to one of the contacts1 and the current flows to the spark plug with which it is connected4 ,an electric current must have a complete path1 or circuit1 in order to be able to flow4 ,in a magneto ignition system this path is partly of wire and partly of the metal of the engine4 ,the diagram in ,figure #de indicates that the current returns to the magneto from the circuit breaker lever and the spark plug by wire1 but in actual construction it returns by the metal of the engine4 ,this is called a ground return2 the circuit is said to be grounded4 ,illustration3 ,,fig4 #eb4--8;,,bosch0 ,,magneto ,,in ,,section ,figure #eb is a side view of a ,bosch magneto1 partly broken away to show the interior4 ,as can be seen1 one end of the primary winding is screwed to the armature1 and is thereby connected with the metal of the magneto2 as the magneto is attached to the engine the primary winding is thus in contact with that also4 ,the other end of the primary winding leads to the insulated block of the circuit breaker1 ,figure #ej4 ,this block is insulated from the disk2 that is1 while it is attached to the disk1 it is kept from touching it by means of pieces of hard rubber or mica4 ,through these an electric current cannot pass4 ,the lever is grounded2 that is1 it is in contact with the metal of the magneto4 ,when the lever touches the screw of the insulated block1 current can flow2 when they are separated1 the circuit is broken4 ,one end of the secondary winding1 ,figure #eb1 is attached to the outer end of the primary4 ,the other end leads to the slip ring1 which is a metal rim on a hard rubber wheel attached to the armature and revolving with it4 ,sparking current flowing to the slip ring is led off by a carbon brush and passed to the distributor4 ,should a spark plug wire fall off while the engine is running1 the current would lose its path and would seek another2 it is quite powerful enough to make a path for itself by breaking through the windings4 ,as this would injure the magneto1 such a thing is prevented by providing a safety spark gap1 which acts like a safety valve in giving the current a path when the regular path is interrupted4 ,it consists of two points of metal1 one attached to the metal of the magneto and the other connected with the slip ring brush2 it is a more difficult path than the one through the spark plug1 but easier than breaking down the windings4 ,figure #ec is a section of the ,k-,w magneto4 ,as the coil does not revolve1 no slip ring is necessary2 the sparking current flows directly to the distributor4 ,illustration3 ,,fig4 #ec4--8,k-,w0 ,,magneto ,,in ,,section ,to start an engine1 the crank shaft must be turned at sufficient speed to drive the magneto fast enough to produce a spark4 ,with large engines this is often a difficult matter1 so it is very usual to equip a magneto with an impulse starter4 ,one part of this is attached to the magneto shaft and the other to the engine shaft that drives the magneto2 the two are connected by a spring4 ,when starting1 a catch holds the armature and prevents it from turning4 ,the drive shaft turns1 however1 and in so doing winds up the spring4 ,at a certain point the catch is automatically released1 and the spring then throws the armature over at a speed that gives a good spark4 ,a spark is thus assured1 even though the engine is being cranked very slowly4 ,,chapter ,,vii ,,battery ,,ignition ,,systems ,while the greater number of tractor engines use magneto ignition1 many use battery and coil systems1 which are the same in general principle as magneto systems1 but produce magnetism in a different manner4 ,copper is a nonmagnetic metal2 that is1 magnetism will not flow through it1 nor can it be magnetized4 ,if a pile of iron filings is stirred with a copper wire there will be no effect1 as might be expected2 but if a current of electricity flows through the wire1 the iron filings will cling to it1 as shown in ,figure #ed1 as if it were a real magnet4 ,illustration3 ,,fig4 #ed4--,,magnetism ,,in ,a ,,copper ,,wire ,it is one of the principles of electricity that when a current flows through a wire1 the wire is surrounded by magnetism1 which continues as long as the current flows2 when the circuit is broken and the current stops flowing1 the magnetism dies away4 ,the magnetism produced is feeble and can be very greatly increased by winding the wire around an iron bar4 ,the magnetism produced by the current then flows into the bar1 and that1 like the core of the winding of a magneto1 throws out magnetism of its own4 ,this is indicated in ,figure #ee4 ,by changing the intensity of the electric current1 or by cutting it off1 the strength of the magnetism can be made to change1 and this change of strength can produce a sparking current4 ,illustration3 ,,fig4 #ee4--,,magnetism ,,from ,,electricity ,the principle employed is illustrated in ,figure #ef4 ,a is a coil of wire wound around one end of an iron bar and connected with a battery2 ,b is an entirely separate coil of wire wound around the other end of the bar1 with its ends separated by a short distance4 ,by closing the battery switch the current will be permitted to flow in coil ,a1 and the bar will become magnetized2 the magnetism that it throws out will be felt by coil ,b4 ,when the switch is opened the current stops flowing and the magnetism dies out of the bar2 these changes in strength will create an electric current in coil ,b1 which will form a spark as it passes across the space between the ends4 ,illustration3 ,,fig4 #ef4--,,principle ,,of ,,spark ,,coil ,in ignition coils1 coil ,b is wound on top of coil ,a4 ,coil ,a1 called the primary winding1 consists of a few layers of coarse wire4 ,the more turns of wire there are in coil ,b1 called the secondary winding1 the more intense will be the current that it produces1 and the intensity is also increased by keeping the windings close to the iron core4 ,the secondary winding is1 therefore1 made of exceedingly fine wire1 and has a very great number of turns4 ,to obtain a spark1 a current is permitted to flow through the primary winding to create magnetism1 and the flow is then stopped to cause the magnetism to die away4 ,the secondary winding is affected by each of these changes in magnetic strength4 ,the bar loses magnetism more rapidly than it gains it1 however2 it is therefore the dying out of the magnetism that has the greater effect on the secondary winding1 and that causes it to produce a sparking current4 ,to use this principle for ignition1 the engine is fitted with a revolving switch1 which closes the circuit as a piston is on the compression stroke1 and then breaks the circuit at the instant when a spark is desired4 ,combined with the revolving switch1 or timer1 is a distributor like the distributor of a magneto1 which passes the sparking current to the cylinder that is ready to receive it4 ,illustration3 ,,fig4 #eg4--8;,,atwater-,,kent0 ,,ignition ,,system ,to produce an intense sparking current1 it is necessary to break the circuit as abruptly as possible1 in order to cause the magnetism to die away suddenly4 ,figure #eg shows how this is done in the ,atwater-,kent system4 ,the parts of the circuit breaker are carried on a plate1 in the center of which revolves a shaft with a notch in it4 ,against the side of this shaft rests the hooked end of the sliding catch2 as the notch comes under this hooked end1 the sliding catch is drawn forward1 only to be snapped back by its spring as the notch moves from under it4 ,the lifter is a bit of metal1 pivoted at one end1 with its free end lying between the sliding catch and the flat steel spring that carries one of the contact points4 ,a1 ,figure #eg1 is a diagram of the system4 ,b shows the position of the parts as the notch carries the sliding catch forward1 and ,c shows their positions as the spring snaps the sliding catch back to its place4 ,it will be seen that in thus moving back it strikes the lifter1 which in turn moves the contact spring1 and so closes the circuit2 but the circuit is instantly broken as the parts spring back to position4 ,the movement of the parts is so rapid that to the eye they seem to be standing still4 ,the circuit is closed only for an instant1 but that is sufficient to magnetize and demagnetize the coil1 and to produce a sparking current4 ,the operation of this system depends on the very great swiftness with which the circuit is made and broken2 there is not sufficient time for the core to get thoroughly magnetized1 but such magnetism as is produced changes strength so quickly that it gives a sufficiently intense current to create an ignition spark4 ,in other battery systems of like principle1 the circuit is closed for a long enough time to allow the core to become fully magnetized1 the circuit then being suddenly broken4 ,in some of these systems the timer breaks the circuit1 while in others it is broken by the magnetism1 through a vibrator4 ,a vibrator coil system is illustrated in ,figure #eh4 ,the timer is a ring made of some kind of insulating material1 with a plate of metal set in it and forming one of the timer contacts4 ,the other contact is the revolving brush1 driven by the engine2 the circuit is closed when the brush touches the metal plate4 ,illustration3 ,,fig4 #eh4--,,vibrator ,,coil ,,ignition ,,system ,opposite the end of the core is a flat steel spring1 or vibrator blade1 resting against the tip of a screw2 when the core is magnetized it draws the end of the blade to it1 and separates it from the screw4 ,the battery current flows from the timer contact to the screw1 then to the vibrator blade and to the primary winding of the coil4 ,the core then becomes magnetized1 and draws the blade away from the screw1 which breaks the circuit2 this causes the magnetism to die away1 and a sparking current is produced in the secondary winding of the coil4 ,the vibrator blade1 no longer held down by the magnetism1 springs back against the screw2 the circuit is again made1 and the action is repeated4 ,the movement of the vibrator blade is very rapid1 being some hundreds of vibrations a second4 ,illustration3 ,,fig4 #ei4--,,spark ,,plug ,a spark plug is illustrated in ,figure #ei4 ,it consists of a metal shell screwed into the cylinder1 enclosing an insulator of porcelain1 mica1 or some similar material4 ,through the insulator passes the center electrode1 which is a rod of metal1 with its lower end separated by a short distance from the shell or from a wire attached to the shell4 ,this separation is the gap across which the sparking current passes1 and at which the spark occurs4 ,spark plugs receive the pressure of the power stroke1 and must be strongly made in order to withstand it4 ,a leaky spark plug will cut down the power of the engine1 just as a leaky valve will4 ,,chapter ,,viii ,,transmission ,the parts of a tractor by which the power of the engine is applied to the driving wheels are called the transmission1 and include the clutch1 the change speed gear1 the differential and the drive4 ,it has been shown that a gas engine delivers power only when it is running at speed2 it cannot run until some outside power drives it through the inlet and compression strokes4 ,the tractor cannot move until the engine is running and delivering power1 and it follows1 therefore1 that it must be possible to disconnect the engine from the driving mechanism in order that it may run independently4 ,this is done by means of a clutch1 which is a device that connects two shafts1 or disconnects them4 ,illustration3 ,,fig4 #fj4--;,,internal ,,clutch ,a clutch must be so made that when it is engaged it takes hold1 not suddenly1 but gradually4 ,if it took hold suddenly1 the tractor would be required to jump at once into full motion2 this would cause a severe straining of the parts and probable breakage4 ,the alternative would be the abrupt stopping of the engine1 and this would also strain things4 ,by making the clutch in such a way that it slips1 and takes hold little by little1 the tractor starts slowly1 and gradually comes up to speed2 the slipping of the clutch then ceases1 and it takes hold firmly4 ,all clutches operate by the friction of one surface against another2 in some1 the surfaces are curved and in others flat1 while in still others the clutch is a band around a wheel1 or drum4 ,a clutch is operated by a hand lever or by a foot pedal4 ,figure #fj shows a type of clutch that operates inside a drum1 which is often the overhanging rim of the flywheel4 ,the shaft in the center is independent of the flywheel1 and it is the purpose of the clutch1 which is attached to the shaft1 to lock the shaft and flywheel together when the tractor is to be started4 ,the brake shoes1 which bear against the drum1 form the ends of pivoted levers1 and are lined with an asbestos material that resists the heat caused by the friction against the drum4 ,a cone-shaped block of steel slides lengthways on the shaft2 when it is pushed into position1 it forces out the yokes1 and thus presses the brake shoes against the drum4 ,a plate clutch1 or disk clutch1 is shown in ,figure #fa4 ,the principle of a plate clutch may be illustrated by placing a half-dollar between two quarters and pinching them with the thumb and forefinger4 ,if they are held loosely1 the half-dollar may be turned between the quarters1 but if they are pinched tightly1 the friction between the coins will be so great that one cannot be turned without turning the others4 ,illustration3 ,,fig4 #fa4--,,plate ,,clutch ,attached to the flywheel are studs1 which support a disk1 or plate2 this plate revolves with the flywheel1 and is practically a part of it4 ,on either side of this plate are other plates that are supported on the drive shaft2 they revolve with it1 but can slide along it4 ,the end of the shaft is square and fits a square hole in a collar1 so that while the collar may slide along the shaft1 the two must turn together4 ,cams are mounted on the hub of one of the plates in such a position that they can press the outside plates together and pinch the flywheel plate between4 ,the cams are operated by pressing the collar against them4 ,the first drawing shows the clutch out1 or released2 the flywheel may then turn without turning the shaft1 for the plates are not in contact4 ,the second drawing shows the clutch in1 or engaged4 ,the collar is pressed against the cams1 and the plates in turn are drawn together1 pinching the flywheel plate between them4 ,the flywheel and the drive shaft then revolve together4 ,plate clutches are often made with more than three plates2 some makes run in a bath of oil1 and some are intended to work dry4 ,in a cone clutch1 the overhanging rim of the flywheel is funnel-shaped1 and into it fits a cone-shaped disk carried on the end of the drive shaft4 ,to engage the clutch1 the disk is slid along the shaft against the flywheel1 the friction between the two being sufficient to drive the shaft4 ,when a clutch is thrown in it should take hold gradually1 slipping at first1 but finally having a firm grip4 ,when it is thrown out1 it should release instantly and completely4 ,the power delivered by an engine depends on the bore and stroke of the cylinder1 and on the speed4 ,the greater the bore1 or diameter of the cylinder1 and the greater the stroke1 or distance the piston moves in a half-revolution of the crank shaft1 the larger will be the combustion space1 and the larger will be the charge of mixture that it can take in2 the larger the charge1 the greater will be the power produced when the charge burns4 ,each cylinder produces power once during every two revolutions of the crank shaft2 if the engine runs at #a1jjj revolutions per minute there will be twice as many power strokes as there would be if it ran at #ejj revolutions per minute1 and during that minute it will produce twice as much power4 ,a traction engine is intended to run at a certain speed1 at which it will produce its greatest power without overstraining its parts4 ,this normal speed for any particular engine depends on the number of cylinders1 their size and design1 and other details established by the manufacturer4 ,to get the best from the engine1 this is the speed at which it should always be run4 ,the power required to move the tractor depends on various things2 the hardness and smoothness of the ground1 the grade1 the load it is pulling1 and so on4 ,the tractor might be running on level ground1 pulling so great a load that the engine is called on for all of the power that it can deliver4 ,on coming to a hill1 still more power will be required1 for now the tractor and its load must be lifted as well as moved forward4 ,the engine1 already working at its limit1 cannot deliver the extra power needed1 and will slow down and stop unless something is done to aid it4 ,in such a case1 the change speed gear is used to give the engine a greater leverage on its work1 just as a block and tackle gives a greater leverage or purchase to a man who must lift a heavy weight4 ,let us say that the normal speed of the engine is #a1jjj revolutions per minute1 and that it is so connected that it makes #dj revolutions while the driving wheels make #a1 the speed of the tractor being #c miles per hour4 ,if it is a #d-;cylinder engine there will thus be #hj power strokes to every revolution of the driving wheels4 ,the engine is delivering its full power and cannot do more should the tractor be called on for an extra exertion1 such as climbing a hill or crossing rough ground4 ,by changing the connections between the engine and the driving wheels1 the engine can be made to run twice as many revolutions to one turn of the driving wheels1 which will give double the number of power strokes2 the wheels will thus be turned with twice the force4 ,as no change is made in the speed of the engine1 the wheels will now turn at half their former speed1 and the tractor will run at #a miles per hour4 ,it will1 however1 have twice the ability to overcome obstacles4 ,this change in the connections between the engine and the drive is performed by the change speed gear1 which is driven by the engine and which in turn drives the wheels4 ,there are many varieties of change speed gears1 but the main principle in them all is the same1 for they depend on the action of cog-wheels1 or gears4 ,when two gears running together1 or in mesh1 have the same number of teeth1 they will revolve at the same speed4 ,if one has half as many teeth as the other--#aj teeth and #bj1 let us say--the #aj-tooth gear will make two revolutions while the #bj-tooth gear is making one4 ,there are two shafts in a change speed gear1 one driven by the engine and the other driving the wheels2 each carries gears that mesh with gears on the other shaft4 ,these pairs of gears are of different sizes1 and any pair may be used2 the shaft driven by the engine runs as the engine runs1 while the speed of the other shaft depends on the pair of gears that is being used4 ,by changing from one pair of gears to another1 the driven shaft1 and1 consequently1 the wheels1 may be run at a greater or less number of revolutions1 while the speed of the engine and the driving shaft do not change4 ,the number of power strokes that occur during one revolution of the wheels is thus changed1 and they turn with more force or with less4 ,high speed1 or high gear1 means the combination of gears that gives the greatest speed to the wheels1 but the fewest power strokes to each revolution4 ,the combination that gives the slowest speed to the wheels1 but the greatest number of power strokes1 is called low speed1 or low gear4 ,many tractors have but two speeds1 a low and a high2 but others have an intermediate combination for conditions too severe for running on high gear but too easy for low4 ,the change speed gear mechanism also provides for reversing or backing the tractor4 ,two gears running together turn in opposite directions1 while in a train of three gears the outside gears turn in the same direction4 ,the usual combination in a change speed gear uses two gears for going ahead2 to run the driven shaft the other way1 which will make the tractor back1 a third gear is meshed between the two4 ,the differences between various makes of change speed gears are in the methods used to put into action the desired pair of gears4 ,illustration3 ,,fig4 #fb4--,,principle ,,of ,,sliding ,,gear ,two general plans are used4 ,in one of them1 a gear of each pair can slide endways on its shaft1 but must revolve with it2 thus it can be slid into mesh or out4 ,in the other1 the gears of a pair are always in mesh1 but one of them is loose on its shaft1 so that shaft and gear can revolve independently4 ,to make the pair of gears operate1 the loose gear is locked to its shaft4 ,figure #fb shows the principle of the sliding gear type4 ,one part of the shaft driven by the engine is square1 and fits into square holes in its gears1 which may thus slide along it1 but must revolve with it4 ,each sliding gear is moved by a shifter block1 which is operated by a shift lever4 ,there is a shifter block for each gear1 and the shift lever may be moved sideways to operate either one of them4 ,figure #fc shows the jaw clutch type of change speed gear1 in which the gears are in mesh all of the time1 but run loose on their shaft when they are not working4 ,the drawing shows bevel gears1 which are used when the driving and driven shafts are at a right angle4 ,the same principle is used for spur gears on shafts that are parallel1 as in ,figure #fb4 ,illustration3 ,,fig4 #fc4--,,principle ,,of ,,jaw ,,clutch ,,change ,,speed ,,gear ,the center of the shaft is square1 and fits a block that can slide endways1 but that must revolve with it4 ,the ends of the block have heavy teeth that can mesh with teeth on the hubs of the loose gears2 meshing the block with one of the gears forces that gear to revolve with the shaft4 ,the drawing shows only one speed forward2 the reverse is obtained by a second gear on the same shaft1 which is placed on the opposite side of the center of the driven gear1 and turns it in the opposite direction4 ,when a tractor turns1 the outside wheel makes a larger circle than the inside wheel1 and has a longer path to travel4 ,both wheels travel their paths in the same time1 so it follows that the outside wheel must move faster than the inside wheel1 although both are being driven by the engine4 ,this is allowed for by the differential1 which is driven by the change speed gear1 and which in turn drives the wheels2 it operates automatically by the difference in the resistance to the rolling of the wheels4 ,the action of the differential is illustrated by an experiment that requires a pair of wheels on an axle1 like buggy wheels1 and a stick long enough to reach from one to the other4 ,with the wheels on smooth ground1 put the ends of the stick through the wheels at the top1 each end pressing against a spoke4 ,hold the stick at its center and push it forward2 the stick will transmit the pressure to the spokes1 and the wheels will turn4 ,the wheels being on smooth ground1 there is equal resistance to their movement1 and they will run straight forward4 ,now repeat the experiment with the wheels so placed that one is on a smooth roadway and the other on sand2 as the wheel on the smooth surface meets with less resistance than the other does1 it moves faster1 and the pair of wheels circles1 although the stick applies equal pressure to both4 ,the power developed by the engine is transmitted by the differential to both rear wheels2 when the wheels meet with equal resistance1 they turn equally1 but when one wheel meets with greater resistance than the other1 it slows down1 while the other speeds up to correspond4 ,a tractor with two driving wheels must use a differential in order to make turns easily4 ,without a differential1 the wheels would run always at equal speed1 and in making a turn one would be obliged to slip4 ,the use of a differential has a disadvantage1 however4 ,if one wheel is in a mudhole and the other is on hard ground1 the wheel in the mud meets with little resistance1 and all of the power of the engine goes to it2 it spins without moving the tractor1 while the other wheel remains stationary4 ,in such a case all of the power should be applied to the wheel that has traction in order to move the tractor1 but this the differential fails to allow4 ,in some tractors the differential is so made that the parts may be locked together4 ,this lock is used when one wheel is in a mud hole1 and as by its use power is transmitted equally to both wheels1 the tractor moves4 ,great care must be taken to unlock the differential as soon as the need for the lock has passed1 for otherwise the wheels would slip on a turn1 and the parts of the transmission might be strained or broken4 ,a differential is usually made with two bevel gears placed face to face2 between them is a frame holding three or more small bevel gears that are in mesh with them both4 ,the engine revolves the frame with its small gears2 each of the large bevel gears revolves a driving wheel4 ,when the tractor moves straight ahead the differential turns as if it were one solid piece4 ,when there is less resistance to one driving wheel than to the other1 the small bevel gears1 in addition to revolving with the frame that carries them1 turn on their shafts4 ,this transmits the power of the engine to one wheel more than the other1 according to the resistance of the wheels4 ,illustration3 ,,fig4 #fd4--8;,i4 ,h4 ,c40 ,,chain ,,drive1 ,,showing ,,the ,,differential ,figure #fd shows one of the large bevel gears of a differential1 with the three small gears1 the other large bevel gear being removed4 ,a differential in section is shown in ,figure #fe4 ,a tractor with only one driving wheel has no differential4 ,such tractors usually have two wheels1 but one of them runs loose on the axle1 and serves only to support the tractor4 ,the rear axle construction of a tractor with a #a-wheel drive is shown in ,figure #ff1 which should be compared with the #b-wheel rear construction shown in ,figure #fe4 ,illustration3 ,,fig4 #fe4--8;,,case0 ,,rear ,,axle ,there are a number of methods used for transmitting power to the driving wheels4 ,in ,figure #fd a chain is used2 there are tractors with but one chain1 and others with a chain for each driving wheel4 ,illustration3 ,,fig4 #ff4--8,,oil-,,pull0 ,,rear ,,axle ,the most usual method is by a master gear1 or bull gear1 which is a large and heavy gear attached to the driving wheel1 as shown in ,figures #fe and #ff4 ,in some tractors this gear is nearly the size of the wheel1 and is fully exposed2 in others it is smaller1 and enclosed in an oil-tight housing4 ,illustration3 ,,fig4 #fg4--;,,driving ,,worm ,the small gears that drive the bull gears are on the ends of the cross shaft1 called the jack shaft1 that carries the differential4 ,in the ,fordson tractor the differential is built into the axle1 as it is in an automobile1 and power is applied by a worm4 ,the worm is driven by the change speed gear1 and is a screw meshing with a gear on the differential1 whose teeth are cut at the proper angle to make them fit the threads of the worm4 ,a worm1 which is shown in ,figure #fg1 is always enclosed1 and runs in oil4 ,,chapter ,,ix ,,tractor ,,arrangement ,the uneven ground over which tractors must work requires the weight to be kept low1 to prevent capsizing1 and they are also built wide1 for the narrower they are the more easily they tip over4 ,they cannot be broad in front1 however1 for if they are the steering wheels cannot be swung enough to permit them to turn in the small circle that is desirable4 ,to give a small turning circle some tractors are built with the front of the frame raised enough to permit the wheels to cut under4 ,others use small steering wheels1 but this is not desirable because small wheels will not run over rough ground as readily as large ones1 and steering is difficult4 ,illustration ,illustration3 ,,fig4 #fh4--,,tractor ,,arrangement ,illustration ,illustration3 ,,fig4 #fi4--,,tractor ,,arrangement ,types of tractors are indicated in ,figures #fh and #fi4 ,a has a #d-;cylinder vertical engine in front1 driving both wheels by bull gears1 while ,b is a #b-;cylinder horizontal engine in the center1 driving both wheels by chains4 ,c has a #d-;cylinder vertical engine set across the frame4 ,these three types have riveted steel frames1 to which the parts are attached4 ,in ,d1 the drive is entirely enclosed within the rear axle housing1 and the rear part of the frame is formed by the axle housing and the housing of the change speed gear4 ,e has a #a-;cylinder horizontal engine with a single chain drive1 while ,f has a similar engine but drives to both wheels4 ,g has no frame1 its place being taken by the crank case of the engine and the housings of the parts of the transmission4 ,g and ,h have #d-;cylinder vertical engines1 ,g driving through an enclosed rear axle and ,h through bull gears4 ,illustration3 ,,fig4 #gj4--8;,,gray0 ,,tractor ,figure #gj has one broad wheel instead of two narrower ones1 this being placed inside of the frame instead of outside4 ,it has a #d-;cylinder vertical engine placed across the frame1 and drives through two chains4 ,illustration ,illustration3 ,,fig4 #ga4--,,types ,,of ,,front ,,axles ,the front axle of a tractor is almost always attached to the frame by a pivot1 so that the wheels will follow uneven ground4 ,some of the forms of front axles are shown in ,figure #ga4 ,illustration3 ,,fig4 #gb4--,,spring ,,support ,the first is a plain bar1 while the second is arched to raise the front of the frame in order to permit the steering wheels to cut under4 ,in the third the wheel axles are mounted on springs1 which take up some of the vibration and act as shock absorbers4 ,the fourth axle shown is built of steel bars riveted together to form a truss1 and the fifth is similar1 with the frame pivot carried on springs4 ,the sketches at the bottom indicate the extent to which the pivoted front axle may swing4 ,figure #gb shows a spring support for the axles1 front and rear4 ,the axle bearing is in a block sliding in guides1 the weight being supported by a heavy spring4 ,,chapter ,x ,,lubrication ,the most important thing in the care of a tractor is to oil it2 every moving part should be lubricated1 and the greatest care should be taken to assure a never-failing supply of oil and grease4 ,carelessness in lubrication is the principal cause of tractor trouble4 ,there is nothing complicated or difficult about keeping a tractor properly oiled2 yet more tractors break down from careless lubrication than from any other cause4 ,every tractor-maker issues an oiling diagram and oiling instructions1 and there is no excuse for an operator whose machine does not get the right kind of lubricant in the right quantity at each place where lubrication is necessary4 ,the cause of wear is friction2 oil reduces friction and so reduces wear4 ,no matter how smooth and highly polished two pieces of steel may be1 there will be friction between them if they are rubbed together1 and they will wear each other4 ,if they are oiled1 the particles of oil will keep the pieces from touching each other1 and there will be no wear4 ,other substances than oil can be used2 there are some kinds of machinery that are lubricated with water1 for instance4 ,for general use1 however1 oil and grease are the best1 and are practically always used4 ,the object of a lubricant is to keep two pieces of metal from touching2 it must therefore be able to get between them1 and must stay there4 ,if the pieces are large and heavy1 there will be much greater pressure on the oil than if they are small and light1 and the oil must be able to withstand this pressure and resist being squeezed out4 ,the oil that would keep the small1 light pieces apart might not be able to stand the pressure of a greater weight1 and might be squeezed out from between two heavy pieces4 ,oil has a tendency to cling to whatever it touches1 and thick oil or grease has more of this tendency than a thin1 or 8runny0 oil4 ,if a thick oil or grease is used on light machinery1 such as a sewing machine1 this clinging tendency would make the machine run hard1 and might even prevent its operation4 ,when oil is heated1 it becomes thinner1 or more 8runny40 ,through this1 an oil used in a hot place might get so thin that it would not lubricate2 and on the other hand1 an oil that works all right in the heat of summer might get so thick on a cold winter day as to be useless4 ,a slow-moving part of a machine uses a thick oil or a grease2 a thin oil must be used for a part that moves at high speed4 ,some of the parts of a tractor move slowly and some at high speed2 some are cool and some are hot4 ,different kinds of lubricants are therefore required1 and it is a grave mistake to use a lubricant that is not suitable to the work that it is required to do4 ,the engine is the most difficult part of a tractor to lubricate1 and the part that suffers most if the supply fails or if the wrong kind of lubricant is used4 ,in the first place1 it is so hot that any oil will burn1 being turned to carbon2 the best that can be expected of an oil is that it will resist burning until it has done its work of lubricating the piston and cylinder4 ,a tractor engine is more difficult to oil than an automobile or truck engine for the reason that it works harder and more steadily4 ,an automobile engine is rarely driven to the limit of its power2 it has frequent opportunities to cool when running down hill4 ,a tractor engine1 on the other hand1 works at its full power all day long with no opportunities to cool off4 ,an oil that gives good satisfaction on an automobile might ruin a tractor engine through its inability to withstand the greater heat4 ,the makers of tractors understand the importance of using proper oils1 and recommend certain brands and grades2 these recommendations should be followed in order to get the best possible results4 ,all makers specify at least two kinds of lubricants1 and most of them three2 one specifies six1 which range from a light sewing machine oil to a grease so thick that it is nearly solid4 ,whatever the recommendations may be1 they should be followed4 ,in general1 lubricants are classified according to their thickness1 and they range from the light oil used for typewriters and sewing machines to grease so thick that it may be cut like butter4 ,the thinnest oil is used for the circuit breaker pivot2 this part is usually moved in one direction by a cam and in the other by a light spring4 ,a thick oil would gum the bearing to such an extent that the spring might not be able to move the lever4 ,illustration3 ,,fig4 #gc4--8,,mogul0 ,,oiling ,,diagram ---------------------------------------- ------------------------- ,,key ,,description ,,quantity ,,lubrication ---------------------------------------- ------------------------- ,,once ,,every ,,hour ---------------------------------------- ------------------------- ,l ,rear axle bearing ,two complete turns ,cup ,grease ---------------------------------------- ------------------------- ,,once ,,every ,,two ,,hours ---------------------------------------- ------------------------- ,a ,differential hub ,one complete turn ,cup ,grease ,b ,rear wheel hub ,one complete turn ,cup ,grease ,c ,differential pinion ,one complete turn ,cup ,grease ,h ,front wheel hub ,two complete turns ,cup ,grease ,t ,governor and cam ,two complete turns ,cup ,grease shaft bearing ---------------------------------------- ------------------------- ,,twice ,,every ,,day ---------------------------------------- ------------------------- ,e ,governor ,oil ,cylinder oil ,f ,outboard bearing ,two complete turns when ,cup ,grease grease cups plowing ,g ,transmission ,one pint ,see note below ,magneto trip ,grease every #e hours ,cup ,grease ,n ,magneto roller and ,oil every #e hours ,oil slide ,j ,steering worm ,keep covered ,cup ,grease ,w ,steering hub grease ,one complete turn ,cup ,grease cups ,v ,steering worm shaft ,oil every #e hours ,r ,lubricator eccentric ,oil every #e hours 7keep wool in pocket7 ,p ,cam roller slide ,oil every #e hours ,k ,valve levers ,fill with oil every #e hours 7keep wool in pockets7 ---------------------------------------- ------------------------- ,,once ,,every ,,day ,,tractor ,,is ,,in ,,use ---------------------------------------- ------------------------- ,u ,steering sector shaft ,one complete turn ,cup ,grease ---------------------------------------- ------------------------- ,d ,,mechanical ,,lubricator ,fill with a good grade of heavy gas engine cylinder oil4 ,turn the crank on the mechanical oiler #dj to #ej times when starting the engine4 ,,important ,in cool or cold weather the oil in lubricator tank must be warmed as it will not flow readily unless of the right temperature4 ---------------------------------------- --------------------------- ,g ,,transmission ,in warm weather1 use heavy oil such as 8#fjj0 transmission or ,polarine transmission oil2 in cold weather1 use a good light oil4 ,s ,,governor ,cylinder oil in governor should cover shoe4 ,m ,,magneto ,oil magneto bearings once a week with sewing machine or cream separator oil4 ---------------------------------------- --------------------------- ,the oil used in an engine is thicker1 and has a high burning point and high viscosity2 that is1 it should be able to resist burning1 and should not get so thin when it is heated that it will be squeezed out of the bearings4 ,the same kind of oil that is used in the engine can be used in many other parts of the tractor4 ,grease is usually used for the gears of the transmission and drive4 ,there is very great pressure between the teeth of two meshing gears1 and only thick oil and grease have sufficient viscosity to resist being squeezed out4 ,the thickest grease is used on the tracks of caterpillar-type tractors4 ,before operating a tractor1 the lubrication chart supplied by the manufacturer should be studied with great care1 and all of its requirements should be observed4 ,this chart is usually in the form of a diagram accompanied by a table1 as shown in ,figure #gc1 which is the lubrication chart of one of the ,international ,harvester tractors4 ,this figure illustrates the constant attention that is demanded by this most important part of tractor operation4 ,illustration3 ,,fig4 #gd4--8;,,illinois0 ,,oiling ,,diagram ,the table calls for four lubricants1 these being sewing machine oil1 which is very thin and liquid2 gas engine cylinder oil2 transmission oil1 which is as thick as molasses2 and cup grease1 which is like butter4 ,the engine is oiled automatically1 the only requirements being to keep the oil tank filled1 and to be sure that the oiler is working4 ,the other parts of the tractor are oiled or greased by hand4 ,figure #gd is the oiling chart of the ,illinois tractor4 ,there are three systems used for engine lubrication3 splash1 force feed1 and by a mechanical oiler4 ,in the splash system1 a pool of oil is maintained in the crank case1 of such a depth that the ends of the connecting rods just dip into it4 ,they strike it with sufficient force to splash it to all parts of the crank case1 the oil that strikes the pistons being carried up into the cylinders and lubricating the walls4 ,the end of the connecting rod is often fitted with a dipper1 as shown in ,figure #ge1 to strike into the oil1 as well as an oil catcher1 shown in the same drawing1 which is a little trough that catches the splashing oil and guides it to the connecting rod bearing4 ,illustration3 ,,fig4 #ge4--;,,end ,,of 8,,twin ,,city0 ,,connecting ,,rod ,to oil the wrist pin bearing there is an oil groove around the piston that collects oil from the cylinder walls2 a hole connects this groove with the hollow wrist pin1 from which other oil holes lead to the bearing4 ,this is shown in ,figure #gf4 ,illustration3 ,,fig4 #gf4--,,wrist ,,pin ,,lubrication ,in the force feed system a pump driven by the engine forces oil through pipes and channels to all of the bearing surfaces4 ,oil collects in a pocket in the crank case1 called the sump1 and is drawn from it by the pump4 ,the sump is usually provided with a wire mesh strainer that separates out any dirt4 ,illustration3 ,,fig4 #gg4--;,,force ,,feed ,,oiling ,,system ,,of 8,,gray0 ,,engine ,from the oil pump the oil is forced to the bearings by pipes and by holes drilled in the crank shaft and other parts1 as shown in ,figure #gg4 ,illustration3 ,,fig4 #gh4--,,oil ,,pump ,an oil pump is illustrated in ,figure #gh4 ,it consists of a plunger driven by the engine1 working in a cylinder provided with two ball check valves1 one for inlet and the other for outlet4 ,on an upward stroke of the plunger the cylinder fills with oil1 which is forced to the engine bearings by the following inward stroke4 ,illustration3 ,,fig4 #gi4--8;,e4,b40 ,,oil ,,pump ,figure #gi shows a similar pump with a strainer over the intake1 the outlet being through the holes ,l in the pipe ,h4 ,in the pump illustrated in ,figure #hj the plunger is hollow1 and fills with oil during an inward stroke2 the oil is forced out to a passage around the plunger1 and passes to the bearings by the holes ,h4 ,illustration3 ,,fig4 #hj4--,,oil ,,pump ,,with ,,hollow ,,plunger ,figure #ha shows two methods of preventing oil from leaking out around the plunger4 ,in the first of these1 a channel is formed in the upper part of the pump cylinder1 leading to the crank case2 any oil that leaks past the plunger flows to the crank case by this drain pipe and is not wasted4 ,in the second method a packing of soft material1 such as cotton or asbestos1 is placed around the plunger1 and is pressed against it by a gland1 which is like a thick washer4 ,a packing nut screws against the gland1 and thus squeezes the packing against the plunger4 ,illustration3 ,,fig4 #ha4--,,methods ,,of ,,preventing ,,oil ,,leaks ,illustration3 ,,fig4 #hb4--8,,titan0 ,,lubricator ,a mechanical lubricator1 or oiler1 consists of several small oil pumps placed in an oil tank1 each pump feeding one special bearing1 and all driven by the engine4 ,figure #hb is a top view of a #b-;cylinder horizontal engine oiled by a six-feed oiler4 ,the bearings that it oils are the two ends of the crank shaft1 the two ends of the cam shaft1 and the two cylinders2 the gears and other bearings are oiled by splash4 ,an oiler is adjustable1 so that it will feed any desired quantity of oil4 ,illustration3 ,,fig4 #hc4--8;,i4,h4,c40 ,,method ,,of ,,oiling ,,crank ,,pins ,figure #hc shows a side view and an end view of the crank shaft of a #b-;cylinder horizontal engine4 ,to each end of the crank is attached a ring1 ,b1 formed into a channel2 oil splashing into this ring is thrown into the channel by centrifugal force1 and flows by holes1 ,a1 to the crank pin bearings4 ,the oil forced to the cylinders from the oiler1 ,figure #hb1 reaches the wrist pin by grooves and holes1 ,a1 ,figure #hc4 ,a #f-;feed oiler is also shown in ,figure #hd4 ,illustration3 ,,fig4 #hd4--8;,,hart-,,parr0 ,,oiling ,,system ,illustration3 ,,fig4 #he4--,,oil ,,cup ,illustration ,illustration ,illustration3 ,,fig4 #hf4--,,proper ,,use ,,of ,a ,,grease ,,cup ,figure #he is an oil cup1 which is used to feed an individual bearing4 ,it is a glass cup holding oil with an opening at the bottom into which fits a needle valve4 ,when the engine is at rest1 the needle valve handle at the top is turned down1 which allows a spring to close the needle valve2 on starting the engine the needle valve is raised1 and the oil flows out by gravity4 ,the dripping oil may be seen through a sight glass at the bottom4 ,in the force feed and oiler systems the oil feeds only when the engine is running1 but with an oil cup the oil feeds all of the time that the needle valve is raised4 ,care must therefore be taken to turn on the oil cup when starting the engine1 and to turn it off when the engine is stopped4 ,change speed gears and differentials are usually enclosed in oil-tight housings that contain a supply of oil or grease4 ,the only attention that is required is to see that they have the necessary amount1 and that the lubricant is of the right kind4 ,illustration3 ,,fig4 #hg4--8,,titan0 #aj-bj ,,oiling ,,diagram ,illustration3 ,,fig4 #hh4--8;,,international0 ,,oiling ,,diagram ,the bearings of wheels and of many other parts of a tractor are lubricated with grease fed by grease cups2 a grease cup has a cover that1 when screwed down1 forces the grease out of a hole in the bottom of the cup4 ,in using a grease cup it is not sufficient simply to give the cover a turn or two2 the cover should be screwed down enough to force an ample supply of grease to the bearing4 ,this is illustrated in ,figure #hf4 ,figures #hg and #hh are oiling diagrams4 ,they show the many points at which a tractor must be lubricated1 and it should be remembered that the failure to maintain a plentiful supply of lubricant at any one of these points will mean the wear and breakdown of that particular part4 ,,chapter ,,xi ,,tractor ,,operation ,before running a new tractor it should be given a careful examination to make sure that all nuts and bolts are tight1 and not secured only by paint2 that all grease cups are in position and filled2 that all parts of the mechanism are properly lubricated2 that oil holes are free from grit1 and that nothing is cracked1 broken or missing4 ,it should be cleaned of cinders and mud that may have collected in shipment1 and in general it should be seen to be in proper condition4 ,a tractor1 like any other piece of machinery1 requires breaking in1 and for the first few days it should be run slowly and with light loads4 ,all parts should be plentifully oiled1 for there will be rough and uneven places on the bearings that must be worn smooth1 and without oil these would heat and be injured4 ,a continual watch should be kept for loose nuts and bolts1 which should be tightened without delay4 ,readjustments of the clutch and brake will be found necessary1 for their linings when new may be lumpy2 as these lumps wear down through use the clutch or brake will begin to slip and must be tightened4 ,when the linings are worn in1 this trouble will disappear1 and readjustments will be necessary only at considerable intervals4 ,special care should be taken to keep the filler caps of the fuel and oil tanks clean and free from dirt4 ,if these are dirty1 the dirt will be carried into the tank when filling1 and will sooner or later cause trouble4 ,the vent holes in the filler caps should be kept clear4 ,if they are plugged with dirt1 air cannot enter the tank to take the place of the fuel that flows out1 and the feed of fuel will stop4 ,beginning when the tractor is new1 a system of daily inspection should be started1 and should be continued for the working season4 ,big trouble starts with small trouble1 and if small trouble is cured without delay1 big trouble will be avoided4 ,trouble usually begins with looseness1 which may be due to a slack nut or bolt1 or may come with wear4 ,if the loose part is not tightened1 it will begin to shift its position2 it will wear1 and will rapidly lead to a breakdown4 ,every day1 without fail1 all parts of the tractor should be inspected for loose nuts1 bolts1 pipe and electrical connections1 petcocks1 drain plugs1 steering connections1 etc4 ,this is also the time for wiping off the working parts1 and cleaning mud and grit from rods1 shafts1 joints1 and other places at which dirt could make its way into bearings4 ,the change speed gears of a tractor should not be shifted while in motion1 this being one of the differences between a tractor and an automobile4 ,in the sliding gear type of change speed mechanism1 the gears slide into mesh sideways1 a tooth of one being opposite a space between two teeth of the other4 ,if the gears are not in the right position for this1 one tooth will strike another1 and the gears cannot be meshed4 ,in such a case the clutch is let in for a slight touch to move one gear1 not for a dozen or twenty revolutions1 but enough to bring a space between two teeth of one gear opposite a tooth of the other4 ,if an attempt is made to shift the gears while they are in motion1 the result will be that one will grind against the other1 and there will be rapid wear and probable breakage4 ,it is because gears cannot be shifted while they are moving that manufacturers instruct users not to attempt to shift on a hill without first blocking the wheels4 ,the reason for this is that the brakes may not hold the tractor1 and if the gears are pulled out of mesh1 the machine may start to run down hill2 as another speed cannot then be engaged because the gears are moving1 there will be no control over the tractor4 ,never coast down hill2 always run with one of the speeds engaged4 ,by switching off the ignition the motion of the tractor will drive the engine1 and this provides the best possible brake4 ,on low gear1 the engine will turn in the neighborhood of eighty revolutions to one turn of the driving wheels1 and the work required to do this will check the tractor on the steepest of practicable grades4 ,a tractor is not built for as accurate and delicate steering as an automobile and should always be slowed in making a turn2 this is especially true when hauling plows or other loads in the field4 ,it is difficult to control the tractor if a turn is made at high speed1 and the machine is liable to tip over4 ,in steering and in engaging the clutch1 the action should not be jerky and abrupt1 but gradual and smooth4 ,letting in the clutch suddenly will start the tractor with a jerk that will strain it from end to end1 and an abrupt swing of the steering wheel will have the same effect4 ,making these motions smoothly and steadily will cause the tractor to change its direction or pace with the least possible strain and effort4 ,this1 of course1 increases the tractor's life4 ,in much of the work done by the tractor1 the varying conditions of field and soil make a continual change in the load1 and the tractor must be handled accordingly4 ,the change from an uphill to a downhill haul1 and from sand or light loam to gumbo1 will require the gears to be shifted in order that the engine may neither labor nor race in keeping the outfit at its work4 ,there should be no hesitation in coming down to low speed when the engine shows by its laboring that the effort of working on high gear is becoming too great4 ,the engine cannot deliver its full power unless its speed is maintained1 and low gear is provided for those times when the load is too great to be handled on high4 ,use high speed whenever it is possible1 but trying to force the tractor to run on high with too great a load will lead to a breakdown4 ,high speed should be used for light work or for moving from place to place1 but the engine should never be run at a greater number of revolutions than that specified by the manufacturers4 ,it is very poor policy to run the tractor fast over rough roads1 as the pounding will inevitably injure it4 ,cold weather changes conditions in the handling and operation of a tractor2 there is difficulty in starting1 lubrication is likely to be faulty1 and there is danger of breakage in engine1 radiator1 and air washer through freezing4 ,difficulty in starting comes from the use of the usual medium grade of gasoline1 which is satisfactory in mild weather1 but will not vaporize at low temperatures4 ,cold gasoline will not vaporize in a cold engine2 to form a mixture it is necessary to use high test gasoline1 which will vaporize at low temperatures1 or to warm the engine to a temperature at which medium grade gasoline will vaporize4 ,it is advisable to keep on hand a few gallons of high test gasoline to use in starting1 or even a mixture of high test gasoline and ether1 half-and-half1 for extreme cold weather4 ,the engine may be warmed by pouring a bucket of hot water into the cooling system1 cranking the engine to get it into the water jackets of the cylinders4 ,another plan is to wrap cloth around the intake manifold and carburetor1 soaking it with hot water1 being careful not to get water into the air intake4 ,a drop of liquid gasoline on the points of the spark plug will short-circuit them and prevent the formation of a spark2 the points should be dry1 and it is an advantage to heat the plugs1 screwing them hot into the engine at the last moment before trying to start4 ,kerosene is thicker when cold than when warm2 it will not flow so freely1 and the needle valve of the carburetor must be opened more in winter than in summer to obtain a proper mixture4 ,lubricating oil also thickens in cold weather1 and flows much more sluggishly4 ,the lubrication adjustments that are correct for summer will therefore be incorrect for winter4 ,this may be provided for to a great extent by using a thinner oil in winter than the oil used in summer4 ,a cold snap is likely to result in burned bearings if the change in lubrication that it brings is not allowed for4 ,grease thickens in cold weather more than oil does1 and some kinds freeze solid4 ,in winter a light1 soft grease should be used1 and the grease cups should be turned down several more turns than is usual when the weather is warm4 ,while antifreezing compounds can be used in the cooling systems of automobiles1 they are not suitable for tractors because the greater and more continuous heat quickly evaporates them4 ,the danger of freezing is very great1 and must be avoided2 the water in the radiator and jackets is in thin sheets1 and will freeze when a bucket of water standing in the open will not show any signs of ice4 ,the only real protection against freezing is to drain out all the water whenever the tractor is to stand idle for a sufficient time for it to cool off4 ,petcocks are provided for this at the lowest points of the system1 and also in the pump when forced circulation is used4 ,the freezing of even a small pocket of water will be enough to crack a cast-iron water jacket wall1 and the best assurance that the system is thoroughly drained is to open the drain cocks while the engine is still running1 shutting down as the flow stops4 ,when putting up a tractor for the winter it should be thoroughly protected from rust and corrosion4 ,the last time that the tanks are filled a quart of light oil should be added for every five gallons of gasoline or kerosene2 as the tank empties this will leave a coating of oil on the inside walls4 ,fuel tanks and water system should be drained1 and particular care should be taken that all the water is out2 the drain cocks should be left open4 ,a mechanical oiler should be filled full1 to protect the steel parts of the pumps from rust4 ,a half pint of thick oil should be put into each cylinder1 and spread to the cylinder and piston walls by cranking for a few turns4 ,oil should be run between the valves and their seats4 ,all exterior parts should be protected by a coat of thick oil or by paint4 ,the governor rod1 push rods1 and similar parts should be especially looked after4 ,it is advisable to take off the magneto and store it in a safe1 dry place2 spark plugs should be left in position4 ,the tractor should be covered with a tarpaulin and stored in a tight shed4 ,when going over a tractor preparatory to laying it up1 a list should be made of all parts that need renewal4 ,these parts should be procured at once2 they are more readily obtained during the winter than in the operating season1 and will be on hand for the spring overhaul4 ,,chapter ,,xii ,,engine ,,maintenance ,,fuel ,,system ,,and ,,carburetor ,the operation of a carburetor depends on so many things that no exact instructions for its adjustment can be given4 ,the best that can be done is to give a general idea of the requirements1 and to outline a plan by which the adjustment can be arrived at4 ,the many makes and designs of carburetors and vaporizers that are used on tractors have different kinds of adjustments2 on most of them the only adjustment is the needle valve that controls the fuel1 but some also have adjustable air valves4 ,in any case1 the manufacturer's instruction book should be studied for the understanding of the particular carburetor in question4 ,the first step in adjusting a carburetor is to get the engine running4 ,the needle valve should be closed1 and then opened enough to give a mixture on which the engine will start2 on many carburetors this will be about one and one half turns4 ,the engine should then be primed2 that is1 a little gasoline should be put in the cylinder1 which may be done with a squirt can4 ,when the engine is running1 and is well heated1 the needle valve should be gradually closed until the engine begins to miss1 and to send jets of flame out of the carburetor1 or little explosions occur in the carburetor4 ,these are signs of a thin mixture1 and the needle valve should be gradually opened to make the mixture richer4 ,the engine will run more steadily1 and will pick up speed until the mixture becomes too rich1 when it will choke and black smoke will come out of the exhaust4 ,the positions of the needle valve for a mixture that is too thin and one that is too rich have thus been found1 and it remains to set it at that point between at which the engine runs most steadily and at the best speed4 ,with adjustable air valves it is usual to adjust for idling1 that is1 the slowest speed at which the engine will run steadily without load1 and then to make any necessary additional adjustment for full speed and power4 ,if a carburetor cannot be adjusted by following the usual methods1 trouble may be looked for1 and this may be in the carburetor itself1 in the fuel supply1 or in the intake manifold1 taking for granted1 of course1 that the engine is in proper condition and that the ignition system is operating correctly4 ,dirt under the float valve will prevent the valve from seating1 and the level in the float chamber will be too high1 so that the mixture is too rich4 ,lifting the valve from its seat will let fuel rush through1 and loose particles will thus be washed away4 ,if dirt is ground into the valve and seat1 or if these parts are worn1 the valve must be reseated1 which is done by turning the valve against its seat with light pressure1 the end of the valve being gently tapped with a light hammer4 ,under no conditions use a grinding compound1 for the particles would become imbedded in the soft metal and would ruin the valve4 ,other causes of flooding are a bent valve1 the sticking of the float pivot1 and the soaking of fuel into the cork float1 which is thereby made too heavy to float properly4 ,the remedy is to dry it1 and then to give it three coats of shellac4 ,a frequent cause of trouble is dirt in the pipe from the tank to the carburetor4 ,while there may not be enough dirt to prevent the engine from running slowly1 it is sufficient to prevent the flow of sufficient fuel for full power4 ,a strainer is always provided1 and this should be drained every day2 if this is not done frequently1 dirt will work its way through4 ,a grain of sand in the spray nozzle will choke it1 and every precaution should be taken to keep this from happening1 as well as the other troubles that dirt brings4 ,the best precaution is to strain the fuel through chamois leather1 or1 if this is not obtainable1 through a very fine metal wire screen4 ,in fuel systems that use a pump1 the sticking of the check valves1 and the leaking of the pump through poor packing1 will cut down the supply of fuel4 ,if air can leak into the carburetor or intake manifold1 the proportions of the mixture will be altered4 ,to test for leaks1 run the engine1 and with a squirt can squirt gasoline on the joints or other places that are suspected of leaking air4 ,if there is a leak1 the gasoline can be seen being sucked in4 ,air must enter the tank to take the place of the fuel that flows out1 and this is provided for by a small hole drilled in the tank-filling cap4 ,if this hole becomes stopped up1 the fuel will not flow1 and the engine will come to a stop4 ,there is a similar hole in the top of the float bowl of most carburetors1 and this also must be kept open4 ,an engine is always started on gasoline1 for that will form a mixture when it is cold4 ,before switching to kerosene the engine must be hot1 and this will take several minutes of running on gasoline4 ,with a double carburetor1 which has a separate fuel bowl and spray nozzle for each fuel1 nothing more is required than the switching of one or the other into action2 when the two parts have once been adjusted1 they require no further adjustment4 ,carburetors that use the same spray nozzle for both gasoline and kerosene will require a readjustment when the switch is made1 for1 as kerosene is thicker than gasoline1 it will require a larger opening for a sufficient quantity to pass4 ,this readjustment is a slight opening of the needle valve on switching to kerosene1 and an equal closing when gasoline is again used4 ,a few minutes before the engine is stopped the carburetor should be switched from kerosene to gasoline1 so that when it is shut down the fuel bowl will contain gasoline and the cylinders gasoline mixture4 ,this is done to make it possible to start the engine4 ,if the engine is stopped on kerosene1 it cannot be started if it has had time to cool4 ,in such a case the fuel bowl must be drained of kerosene and filled with gasoline1 and the engine must be cranked until the cylinders receive a clean gasoline mixture4 ,when an engine is working at full power on kerosene1 it gets much hotter than would be the case with a gasoline mixture4 ,carbon particles in the cylinder1 and projecting bits of metal1 such as thin spark plug points or the edge of a screw thread1 become so hot that they glow1 with the result that they ignite the incoming fresh charge and cause preignition4 ,the effect of this is to cause a pounding or knocking that is very noticeable4 ,it is then necessary to use water1 which is provided for in the carburetor4 ,water has the effect of cooling the intensely heated parts1 and only enough should be used to prevent preignition4 ,when the knocking is heard1 water should gradually be turned on1 using no more than is necessary to stop the noise4 ,too much water will cause the engine to miss by collecting on the spark plug points1 thereby preventing the passing of the ignition spark4 ,hard water should not be used1 for it will form scale1 which will interfere with the action of the carburetor4 ,only soft water should be used1 and preferably rain water4 ,whenever the engine is stopped1 the fuel valve at the tank should be closed to shut off the carburetor supply4 ,if this is not done1 the float valve will be the only thing that prevents the fuel from running out1 and should the float valve leak1 the fuel will be wasted4 ,,magneto ,,and ,,ignition ,,system ,a magneto that is kept clean and properly oiled rarely gives trouble1 and it is a mistake to blame it whenever the engine runs irregularly or will not start4 ,its adjustments should be changed only when the other parts of the engine have been proved to be in good condition4 ,the working parts of a magneto are enclosed1 and practically proof against dust4 ,it should be wiped off frequently1 and dust and grit should not be allowed to collect around the oil holes1 for otherwise it will work into the bearings and damage them4 ,dust and dirt are especially injurious to the circuit breaker1 which should be frequently inspected and cleaned4 ,very little oil should be used on it1 and this should be the light oil used for typewriters and sewing machines4 ,a thicker oil will become gummy1 and will prevent the free action of the lever4 ,if there is much sparking at the platinum points1 so that they become corroded and rough1 it is an indication that the condenser of the magneto is not operating as it should1 for the object of the condenser is to prevent such sparking4 ,the only remedy is to renew the condenser4 ,rough points will spark more than smooth ones2 should they get into this condition1 they should be lightly filed with a file of the cut known as 8dead smooth40 ,if this file cannot be obtained1 pinch a strip of the finest sand paper--not emery paper--between the points1 and draw it gently back and forth1 smoothing down first one point and then the other4 ,in smoothing platinum points the greatest care should be taken to make them flat and true to each other4 ,after smoothing the points they should be readjusted so that when they are separated by the cam they are from _/ to _/ inch apart4 ,a distributor made with a carbon brush that slides across the contacts will require wiping off at least once a month4 ,carbon dust will rub off the brush and collect on the face of the distributor2 in the course of time this will cause a short-circuit4 ,the distributor is always made so that it can easily be cleaned4 ,a magneto is timed to an engine so that when the spark control is fully retarded1 the circuit breaker points are just separating as a piston goes over top center4 ,the engine is cranked until one of the pistons is at top center2 the magneto should be in position1 but its coupling should be loose1 so that the armature can be revolved4 ,the spark control is retarded2 that is1 it is moved as far as possible in the direction in which the armature turns4 ,the armature is then revolved in the direction in which it will be driven by the engine until it is seen that the contact points are beginning to separate2 holding the armature1 the coupling is then made fast4 ,it will now be found that the distributor brush is touching one of the contacts2 that contact is to be connected with the spark plug of the cylinder that is at top center of the compression stroke4 ,the following distributor contacts are connected to the remaining spark plugs in the order in which their cylinders fire4 ,should the magneto be suspected of being out of order1 the first test is to disconnect a wire from its spark plug1 and support the tip inch from the metal of the engine while the engine is cranked briskly2 if a spark appears1 it is evidence that the magneto is operating and that the trouble is elsewhere4 ,if there is no spark1 repeat the test with the switch wire disconnected from the magneto4 ,this wire and the switch form a circuit from the metal of the engine to the insulated part of the circuit breaker2 when the switch is closed1 or in the 8off0 position1 this circuit is completed1 and as the magneto current flows over it instead of over the regular sparking circuit1 no spark is produced at the plug4 ,it sometimes happens that the switch or wire is defective1 and allows the current to take that circuit even when the switch is in the open or 8run0 position4 ,if this is the case it will be shown by a spark on cranking the engine with the switch wire disconnected at the magneto1 and no spark when it is connected4 ,if the switch and wire are all right1 examine the circuit breaker to see whether the contact points are clean1 and that they touch when the cam allows them to2 touch the circuit breaker lever to see that it is free to move and that its spring is not broken4 ,in some tractors the magneto is in such a position that the circuit breaker cannot easily be seen2 in such a case hold a small mirror in front of the circuit breaker and examine the reflection4 ,if the circuit breaker is in good condition1 examine the distributor to see whether it is dirty1 or the brush broken2 if these parts are all right1 the trouble is of such a character as requires the magneto to be returned for repair4 ,ignition trouble is usually in the spark plugs4 ,the insulator cracks easily in many makes1 which will permit the current to leak across without forming a spark2 it is frequently the case that the crack does not show1 and the best test is to replace the suspected plug with a plug that is known to be good4 ,if the cylinder fires with one plug and not with the other1 there is no question as to the cause of the trouble4 ,the insulator of the plug must be kept clean1 for a deposit of carbon on it will form a path by which the current can pass without forming a spark4 ,a dirty plug can best be cleaned by brushing it with a stiff toothbrush dipped in gasoline4 ,a carbon deposit can be softened by soaking the plug in gasoline for a few hours1 and can then be brushed off more easily4 ,the spark gap of a plug should be from _/ to _/ inch4 ,after considerable use the points will be burned off1 and the gap will become too wide2 the points should then be bent to form a proper gap4 ,oil and grease will rot rubber1 and the ignition wires should therefore be wiped clean4 ,oil-soaked cables will give trouble1 and should be replaced with new ones4 ,it is frequently difficult to locate a leakage of current4 ,if the engine is misfiring and losing power1 and a leakage of current through poor insulation is suspected1 the easiest way to detect it is to run the engine in the dark4 ,leaks will show themselves by sparks1 which are then easily seen4 ,,compression ,in order to deliver its full power a gas engine must have good compression1 and compression should frequently be tested by cranking the engine slowly and steadily with the ignition switched off4 ,if compression is good1 there will be a springy1 elastic resistance that becomes greater as a piston approaches the end of a compression stroke1 and that throws the piston outward as dead center is passed4 ,compression should be the same for all cylinders4 ,if there is a leakage of compression1 the only resistance will be from the bearings1 and it will be the same for all parts of the stroke4 ,a compression leak often makes a hissing noise that can be distinctly heard1 and by which it can be located1 but more often it makes no sound1 and its location must be found by testing4 ,the leak may be at any of the openings into the combustion space2 at the valves1 around the spark plugs or piston rings1 or at the cylinder head gasket4 ,to discover whether the gasket leaks1 run gasoline along the line of the gasket joint with a squirt can while the engine is being cranked briskly2 at a leaky place it will be sucked in or blown out4 ,the same test should be made around the spark plug4 ,the remedy is to reset the cylinder head1 using a new gasket1 and being sure that the surfaces are clean and free from grit4 ,piston ring leaks are usually caused by the rings sticking in their grooves through the formation of carbon4 ,to test for piston ring leaks1 pour a half pint of cylinder oil into each cylinder1 and crank the engine slowly4 ,the oil will form a seal around the pistons1 and if compression is then improved1 the rings are shown to be at fault4 ,to free the rings1 pour a few tablespoonfuls of kerosene into each cylinder1 and spread it by giving the engine a few turns2 after standing for an hour or so the carbon should be sufficiently softened to free the rings4 ,if the leakage of compression is due to the rings being worn and loose in their grooves1 they must be replaced4 ,the most usual cause of compression loss is leaking valves4 ,with its continual pounding against its seat1 and the heat to which it is exposed1 a valve and its seat will become rough and pitted1 and will leak2 when in this condition the valve must be ground4 ,a valve is ground by spreading grinding compound on the seat1 and turning the valve against it4 ,this requires the valve spring to be taken off2 the exact method of doing this depends on how these parts are made4 ,if the valves are in a removable cylinder head1 valve grinding is most easily done by taking the cylinder head to a bench4 ,in many designs the valve seats are part of the cylinder casting1 and the job is done on the tractor4 ,in grinding a valve the valve is not turned around in one direction only1 for this would cut grooves in the valve and seat4 ,to obtain smooth surfaces the valve should be given part of a turn in one direction1 and then turned equally in the other direction2 after every few turns the valve should be lifted and dropped to another position on the seat4 ,in this way the grinding is made even all around4 ,illustration3 ,,fig4 #hi4--;,,grinding ,,valve ,,in ,,engine ,,with ,,fixed ,,head ,the best tool for valve grinding is a carpenter's brace with a screw driver blade fitting the slot in the valve1 as shown in ,figure #hi4 ,this drawing illustrates a cylinder with a fixed head2 the valve is reached by unscrewing the plug from the opening directly above it4 ,when grinding valves in an engine of this design the opening between the valve pocket and the combustion space should be plugged with a rag or waste to prevent the grinding compound from getting into the cylinder4 ,with the valve grinding tool in position1 swing the handle back and forth ten or twelve times2 then lift the valve1 place it in a new position1 and repeat4 ,the valve is lifted most easily by a light spring placed under the valve disk1 as shown in ,figure #hi4 ,from time to time the valve disk and seat should be cleaned off and examined to see whether they are smooth and free from pits and scores4 ,if they appear to be1 make marks around the valve disk with a lead pencil1 replace the valve1 and give it a complete turn4 ,if this wipes off the pencil marks all around the valve1 the grinding is complete1 and the valve may be replaced with its spring and spring retainer4 ,it is not necessary to grind until the entire thickness of the valve disk and seat are smooth2 a narrow band all around will make the valve tight4 ,after grinding1 and before replacing the valve1 all traces of the grinding compound should be wiped off1 and great care taken that none of it gets into the cylinder1 valve stem guide1 or other working part4 ,illustration3 ,,fig4 #ij4--;,,grinding ,,valve ,,in ,,detachable ,,head ,on an engine with a removable head containing the valves1 the head may be taken to a work bench1 which makes grinding easier4 ,this is illustrated in ,figure #ij4 ,on an engine in which the valve and its seat may be taken out1 the seat may be clamped in a vise1 as shown in ,figure #ia4 ,with valves of either of these types1 the grinding may be tested by turning the head or the seat so that the disk is down1 and pouring in gasoline4 ,if the valve is not tight1 the gasoline will leak through1 and grinding must be continued4 ,illustration3 ,,fig4 #ia4--;,,grinding ,,valve ,,in ,,detachable ,,seat ,when a valve seat is very badly worn it must be redressed1 which is done with a cutting tool to be obtained from the maker of the tractor1 and illustrated in ,figure #ib4 ,this has a stem fitting the valve stem guide which centers the tool and assures a true cut4 ,if a seat is so worn as to need redressing1 the valve will be in such bad condition that it must be discarded and a new one used4 ,this must be ground in before the engine is run4 ,grinding a valve lowers it in its seat1 and usually makes it necessary to readjust the push rod4 ,when an engine is cold there is a space of about _/ inch somewhere between the cam and the valve stem2 in ,figure #ic1 this space is shown to be between the valve stem and the rocker arm4 ,as the engine heats up the valve stem lengthens1 and this space permits it to do so4 ,illustration3 ,,fig4 #ib4--,,valve ,,seat ,,cutter ,if the space is too small1 the stem will come against the rocker arm or the push rod1 and the valve will be held off its seat1 causing a compression leak4 ,if the space is too great1 the valve will open too late and close too early4 ,the space must therefore be carefully adjusted1 and this is arranged for on practically all makes of tractor engines4 ,illustration3 ,,fig4 #ic4--8;,,holt0 ,,valve ,,arrangement ,one-thirty-second of an inch is the thickness of a #aj-;cent piece2 it should just be possible to slip a slightly worn dime into the space when the engine is cold4 ,,valve ,,timing ,by timing the valves is meant the setting of the cam shaft in such a position that the valves are opened at the correct point in the stroke4 ,it is necessary to time the valves only when the cam shaft has been taken out and must be replaced4 ,the principle of valve timing should be understood1 however1 in order to be able to tell whether an engine is timed correctly4 ,it will usually be found that the face of the flywheel bears letters and figures that are indicators of the timing of the valves4 ,this arrangement on the ,e-,b engines is shown in ,figure #id4 ,two lines are cut in the face of the flywheel1 one marked ex4 cl4 #a-d1 which means exhaust valve closes1 cylinders #a and #d1 and the other marked ,,center #a-d1 to indicate that the pistons in those cylinders are on center4 ,a straight-edge is held against the finished surface of the housing and the crank shaft is turned to bring one of the marks in line with it2 at that point the valves or pistons are as indicated by the lettering4 ,illustration3 ,,fig4 #id4--,,valve ,,timing1 ,,using ,,marks ,,on ,,flywheel ,illustration3 ,,fig4 #ie4--,,valve ,,timing ,the flywheel is also marked with a dot to indicate the firing point4 ,when the dot is in line with the straight-edge1 ignition should occur with the spark control fully advanced4 ,figure #ie shows the valve arrangement of the same engine1 with the exhaust valve just closing2 the point of the cam has passed under the lifter or push rod1 and has permitted the valve to come to its seat1 but is still holding the lifter against the valve stem4 ,to check the valve setting1 hold a slip of tissue paper1 such as a cigarette paper1 in the space between the lifter and the valve stem1 while the engine is cranked slowly4 ,while the cam is holding the valve off its seat the paper will be pinched between the lifter and the valve stem and held firmly4 ,at the instant when the paper is freed and can be moved1 the valve is seated and the point of the cam is just passing from under2 the proper mark on the flywheel should then be in line with the straight-edge4 ,as the cams for all valves are in one piece with the cam shaft1 setting one valve sets them all and checking the setting of one checks the setting of all4 ,before taking out a cam shaft1 two adjoining teeth of its gear should be marked with a prick punch or a small cold chisel1 and a similar mark should be made on the tooth of the crank shaft gear that comes between them4 ,in replacing the cam shaft it is then necessary only to return the teeth to the same position4 ,timing gears are usually marked in this way by the manufacturers4 ,,carbon ,a kerosene lamp that is turned too high gives a dense black smoke that is composed of fine particles of carbon4 ,a piece of paper held in the smoke is quickly covered with a deposit of carbon1 commonly called soot1 or lamp-black4 ,all fuel oils and lubricating oils contain carbon4 ,when these oils burn in the cylinder1 they produce carbon1 much of which passes out of the exhaust1 while the rest deposits on the valves and on all parts of the combustion space4 ,this deposit hardens1 and eventually makes trouble through causing preignition4 ,the deposit is rough1 and the heat in the cylinder is sufficient to make the outstanding particles glow2 they ignite the incoming charge1 and cause preignition4 ,the sign of carbon trouble is a sharp knocking in the cylinder1 especially when the engine is under a heavy load4 ,the sound is the same as that caused by too great an advance of the spark4 ,carbon deposit can be greatly reduced by pouring a few tablespoonfuls of kerosene into each cylinder and cranking for a few turns to spread it to all parts of the combustion space4 ,this will soften the carbon and much of it will be blown out when the engine is next started4 ,best results will be obtained if the kerosene is poured in after a run1 when the engine is hot4 ,if the carbon deposit is too hard to be softened by kerosene1 it can be removed by scraping4 ,this requires the cylinder head to be taken off1 when the deposit can be scraped and chipped with a screwdriver4 ,care should be taken to keep the carbon crumbs from getting into the cylinders1 valve stem guides1 or other places where it would cause wear4 ,in taking off the cylinder head the gasket should be handled carefully1 and protected from denting and bending4 ,a battered or bent gasket is a sure cause of compression leaks4 ,in replacing a metal gasket1 give it a coat of cylinder oil on both sides to improve its seating4 ,when replacing the cylinder head1 set all of the bolts up a little at a time1 instead of screwing some of them tight while others are loose4 ,one bolt drawn tight may tilt the cylinder head slightly1 and there will be a distortion when another bolt is tightened4 ,this is avoided by setting up all of the bolts a little at a time4 ,running on too rich a mixture1 giving the engine too much oil1 and not using an air cleaner in dusty work will carbonize an engine rapidly4 ,blue smoke at the exhaust is a sign that too much lubricating oil is being used2 black smoke indicates too rich a mixture4 ,carbonizing can be greatly reduced by careful adjustment of the lubricator and carburetor4 ,,chapter ,,xiii ,,locating ,,trouble ,there are many ways in which an engine can give trouble1 but these are not serious to an operator who understands the action of an engine1 and who works with his brain as well as with his hands4 ,each of these troubles has a distinct cause2 proper care will avoid them1 but if they come the reasons for them can be determined by simple tests4 ,in order to develop full power1 an engine must be in good mechanical condition2 that is1 the bearings must be free without being loose1 the gears must run well1 the pistons and their rings must not bind or be too free1 and so on4 ,it must be properly lubricated and cooled1 compression must be correct1 it must get a good mixture1 and ignition must take place at the right time4 ,if an engine gives trouble1 it is because one of these systems is not working properly1 and it is not at all difficult to locate the cause and to correct it4 ,if an engine gets a good mixture1 which is ignited properly1 it will run2 if it will not give any explosions it is because one or the other of these systems is not working properly4 ,an inspection or a simple test will show which one is at fault4 ,,engine ,,will ,,not ,,start ,if an engine will not start after being cranked a dozen or twenty times1 it is useless to continue to crank it4 ,it is not getting either a proper mixture or an ignition spark1 and it saves time and energy to find out where the trouble is1 rather than to keep on cranking in the hope that something may happen4 ,when a tractor engine refuses to start1 the trouble is usually with the mixture1 and1 more often than not1 this is due to carelessness or to forgetfulness4 ,the tank may be empty1 or the fuel valve may be closed1 so that the carburetor is dry2 see if there is fuel in the carburetor bowl4 ,the engine may have been shut down while running on kerosene1 instead of having been switched to gasoline for the last few minutes of its run1 so that the carburetor1 intake manifold and cylinders contain kerosene1 which will not vaporize without heat1 instead of gasoline1 which will4 ,in this case the engine must be primed with gasoline4 ,if too much gasoline has been used for priming1 the cylinders may contain a mixture that is too rich to ignite2 the engine should then be cranked briskly with the fuel shut off and the compression relief cocks open1 to clear out the rich mixture and fill the cylinders with air4 ,water in the fuel will make starting difficult or impossible4 ,it is easy to forget to shut off the water valve of the carburetor when stopping the engine1 and when starting1 water from this valve will prevent the forming of a mixture and will also interfere with the ignition4 ,if the mixture is apparently all right1 the fault may be in the ignition4 ,a drop of liquid fuel or of water1 for instance1 may be on the spark plug points2 this will short-circuit them and no spark will be formed1 although the sparking current is passing4 ,if there is a suspicion that the ignition system is at fault1 and that the magneto is not producing a sparking current1 it should be tested1 as explained in ,chapter ,,xii4 ,starting in cold weather is always more difficult than starting when it is warm4 ,helps in cold weather starting are given in ,chapter ,,xi4 ,a leaky inlet manifold will admit an extra amount of air that will completely alter the proportions of a mixture4 ,thus the mixture will be wrong1 although the carburetor adjustment seems to be correct4 ,manifold leaks are usually at the joints1 but occasionally a manifold is found with a hole in it due to poor casting or material1 or a crack may develop4 ,difficulty in starting due to poor compression caused by stuck valves or rings will show its cause by the ease with which the engine can be cranked4 ,if an engine is free enough to turn over1 poor lubrication or cooling will not interfere with starting it4 ,faults in these systems show themselves only when an engine is running4 ,,engine ,,loses ,,power ,an engine will lose power through a defect of compression1 carburetion1 ignition1 cooling or lubrication1 or because of a mechanical fault4 ,if the trouble comes from cooling or lubrication1 the engine will overheat and thus make the cause known4 ,a bearing that binds will become very hot1 while if the cooling system fails1 the engine will be hot all over4 ,when the engine is excessively hot1 the pistons will expand1 and much of the power of the engine will be used up in forcing them to move4 ,an engine that is not hotter than usual1 and is having regular and even explosions1 probably loses power through a loss of compression4 ,this is the most usual cause of this trouble1 and it is located and remedied as explained in ,chapter ,,xii4 ,if compression is good1 the loss of power may be due to a clogged muffler or exhaust pipe1 which will not permit the free escape of the burned gases4 ,this condition will prevent full charges of fresh mixture from entering the cylinders1 and the engine then cannot be expected to deliver full power4 ,another possible cause of a loss of power with the engine apparently in proper condition is the sticking or poor adjustment of the governor4 ,the factory adjustment of the governor should not be changed1 however1 until it is definitely proved that that is where the trouble lies4 ,if the engine misses fire1 or runs irregularly1 the loss of power will be due to faulty carburetion or ignition4 ,the mixture may be too rich or too lean2 in either case the trouble will be remedied by readjusting the carburetor4 ,a mixture that is very much too lean will make itself known by backfiring2 there will be little explosions at the carburetor4 ,this should be remedied at once1 for the danger of fire from it is very great4 ,black smoke at the exhaust is a sign of a mixture that is too rich4 ,an engine will not deliver full power if it is run on a retarded spark4 ,a loss of power from this cause will be accompanied by general overheating of the engine4 ,,engine ,,stops ,the manner in which an engine stops will indicate the reason for it4 ,a failure of the ignition system that stops the formation of current1 like the sticking of the circuit breaker lever1 will cut off all explosions instantly2 the engine will stop abruptly4 ,an engine will not stop abruptly from any fault with the mixture2 with mixture trouble the explosions will become weaker and weaker until they cease4 ,if an engine stops through a failure of the lubrication or cooling systems it will be intensely hot1 which will not be the case if the fault is with carburetion or ignition4 ,a running engine will not be brought to a stop by a loss of compression4 ,,engine ,,misses ,a steady or irregular miss in one cylinder is usually due to the spark plug's being cracked or dirty4 ,carburetor trouble will affect all the cylinders2 it cannot affect one cylinder only1 and missing in one cylinder may be put down as ignition trouble4 ,in this case ignition trouble does not mean magneto trouble1 for if the magneto produces sparking current for one cylinder it will produce it for all4 ,therefore ignition trouble in only one cylinder is in those parts of the ignition system supplying that cylinder2 that is1 in the spark plug or in the spark plug cable4 ,a less likely cause for missing in one cylinder only is poor compression4 ,it is usually the case that if compression is poor in one cylinder it is poor in them all1 but a broken valve or piston ring or a weak valve spring will weaken compression in one and not in the others4 ,a cylinder that misses is cooler than the others1 and can be located by feeling4 ,it can also be located by short-circuiting the spark plugs one at a time2 this will make no difference in the dead cylinder1 but when the spark plug of an active cylinder is short-circuited the speed of the engine will drop4 ,to short-circuit a spark plug1 take a wooden-handled screwdriver or other tool and rest the blade on the engine near the spark plug2 then tilt until its shank is close to the spark plug terminal4 ,the spark current will then pass to the metal of the engine by way of the tool instead of by the spark plug points4 ,this is also a test of ignition1 for a spark will pass between the terminal and the tool4 ,irregular missing in all cylinders may be due to a fault at one of the parts of the ignition system that supplies them all2 a dirty distributor1 for instance1 or a sticking circuit breaker lever1 or rough platinum points4 ,it may also be due to a clogged fuel line1 which prevents the carburetor from getting a regular and sufficient flow4 ,irregular missing will also be caused by loose ignition connections1 and by loose switch parts4 ,,engine ,,starts2 ,,but ,,stops ,when an engine starts readily but quickly slows down and stops1 the reason is almost always an insufficient supply of fuel4 ,an obstruction in the pipe may prevent the fuel from flowing fast enough to keep the carburetor bowl filled when the engine is running2 when the engine starts1 the fuel is sucked out of the spray nozzle faster than it comes in through the float valve1 so the carburetor is soon drained and the engine stops4 ,the bowl then fills1 only to be sucked dry again when the engine is next started4 ,this difficulty is caused by dirt in the fuel1 which collects in the strainer or the fuel pipe4 ,the strainer is so arranged that it may be easily drained and cleaned2 to clear out the pipe1 shut off the fuel at the tank1 disconnect the pipe at both ends1 and blow through it4 ,the strainer should be drained every day2 it is sufficient to open the strainer drain cock for two or three seconds4 ,most of the troubles due to dirt in the fuel will be avoided if the fuel is strained when filling the tank4 ,another thing that will bring an engine to a stop is the clogging of the vent holes in the tank filler cap and in the top of the carburetor bowl4 ,these holes should be clear1 so that air can enter to replace the fuel that is used2 if air cannot enter the fuel will not flow1 and the tank is then said to be air-bound4 ,,engine ,,overheats ,an engine may overheat either because it produces more heat than the cooling system can take care of1 or because the cooling system is not taking off all of the heat that it should4 ,running an engine with the spark retarded will cause it to overheat2 so will a failure of the lubrication and an obstruction to the passage of the exhaust gases4 ,if an engine has been taken down and overheats when it is reassembled1 it may be that the magneto has been wrongly timed1 and produces its spark too late4 ,if an engine has been running properly but begins to overheat1 the ignition cause will be the faulty setting of the spark control1 or the slipping of the spark control rod4 ,when an engine is run on kerosene1 the oil in the crankcase must be frequently drained off and replaced with fresh oil4 ,the reason for this is that part of the kerosene that goes to the cylinders does not vaporize and burn1 but works its way past the pistons and into the crankcase1 where it thins the lubricating oil4 ,as the oil thins1 it loses its ability to lubricate1 and the engine begins to overheat4 ,anything that produces extra friction will cause overheating1 as1 for example1 a wrist pin that works endways and rubs against the cylinder wall1 or a tight bearing4 ,for a cooling system to work properly it must contain a full supply of water1 the passages must be clear1 sufficient air must pass through the radiator1 and the pump must be in proper condition4 ,hose connections will rot1 and a strip of rubber may peel off the inside and be drawn across the passage2 or if dirty water is used1 the dirt may choke the fine radiator passages or other channels4 ,if the radiator is covered with mud1 air cannot get at the tubes to take the heat from the water that they contain4 ,a very usual cause of overheating is a slipping fan belt2 an adjustment is provided by which the belt can be tightened when it works loose4 ,,engine ,,smokes ,black smoke indicates that the mixture is too rich2 blue smoke is a sign of too plentiful lubrication4 ,oil that is too thin1 or that is of a poor grade1 will cause smoking2 good quality oil of the grade recommended by the manufacturer should always be used4 ,broken piston rings1 or rings stuck in their grooves1 will be the cause of smoking because they will permit an excess of oil to pass by them4 ,,chapter ,,xiv ,,causes ,,of ,,trouble ,engine will not start4 ,no mixture4 ,no ignition4 ,no compression4 ,engine starts1 ,clogged fuel pipe or strainer4 but will not ,air-bound tank or carburetor4 continue running4 ,clogged exhaust4 ,wet spark plugs4 ,governor out of adjustment4 ,engine loses power4 ,retarded spark4 ,poor compression4 ,overheating4 ,clogged exhaust4 ,incorrect mixture4 ,governor out of adjustment4 ,tight bearings4 ,dragging brake4 ,slipping clutch4 ,overloaded4 ,engine stops suddenly4 ,ignition trouble4 ,engine slows down ,clogged fuel supply4 and stops4 ,incorrect mixture4 ,overheated4 ,regular miss in one cylinder4 ,defective spark plug or wire4 ,irregular miss in all ,sticking contact breaker4 cylinders4 ,defective distributor4 ,clogged fuel line4 ,irregular fuel feed4 ,water in fuel4 ,faulty ignition connections4 ,engine runs unevenly4 ,incorrect spark plug gap4 ,incorrect mixture4 ,binding carburetor float4 ,sticking valves4 ,sticking governor4 ,engine overheats4 ,spark retarded4 ,faulty cooling4 ,faulty lubrication4 ,engine smokes4 ,black smoke2 mixture too rich4 ,blue smoke2 too much oil4 ,broken or stuck piston rings4 ,poor oil4 ,engine backfires ,mixture too lean4 through carburetor4 ,sticking inlet valve or weak inlet valve spring4 ,explosions in exhaust ,missing spark4 pipe4 ,mixture too rich4 ,sticking exhaust valve4 ,,index ,adjusting a carburetor1 #bac ,advance of ignition2 theory of1 #ah ,air cleaner or washer1 #ga ,air inlet2 extra1 #fc ,armature1 #ajf ,atwater-,kent ignition system1 #acf ,automatic carburetor1 #fc ,automobiles and tractors compared1 #a ,axles2 types of front1 #agb ,backfire1 #ee ,balance weights1 #ca ,bearings1 #ca ,bosch magneto2 theory of1 #aaj ,bosch magneto circuit1 #aaa ,bosch magneto windings1 #aaj ,bull gear drive1 #afe ,burning point of oil1 #ahb ,cam1 #ci ,carbon2 formation of1 #ef ,carbonization1 #ef ,carbon2 removing1 #bdb ,carburetor1 #eg ,carburetor action1 #fj ,carburetor adjustment1 #bac ,carburetor adjustment for two fuels1 #bah ,carburetor2 compensating1 #fc ,carburetor connections1 #hi ,carburetor2 description of1 #gb ,carburetor2 float feed1 #gf ,carburetor2 heating the1 #gj ,carburetor2 parts of1 #gj ,carburetor2 pump feed1 #hj ,carburetor2 stopping on gasoline1 #bah ,carburetor strainer1 #hi ,carburetor2 trouble with1 #bae ,carburetor2 using water in1 #bai ,causes of trouble1 #bei ,centrifugal force1 #id ,change speed gear2 action of1 #aeb ,change speed gear2 jaw clutch1 #aef ,change speed gear2 purpose of1 #f ,change speed gear2 shifting1 #bjc ,change speed gear2 sliding1 #aed ,change speed gear2 theory of1 #adi ,choke1 #fg ,circuit2 ,bosch magneto1 #aaa ,circuit breaker2 magneto1 #aaj ,cleaner2 air1 #ia ,clutch2 action of1 #add ,clutch2 expanding1 #ade ,clutch2 how to use1 #bje ,clutch2 plate or disk1 #adf ,clutch2 purpose of1 #f ,cold weather care of tractor1 #bjg ,cold weather starting1 #bjg ,combustion space1 #aa ,combustion2 theory of1 #eb ,compression2 importance of1 #af ,compression leaks2 locating1 #bbh ,compression stroke1 #af ,compression2 testing the1 #bbg ,connecting rod1 #ce ,cooling system1 #df ,crank shaft1 #cj ,cycle2 gas engine1 #aa ,dead strokes1 #ab ,differential2 action of1 #afa ,differential2 purpose of1 #g ,differential2 theory of1 #aeh ,dirt in the fuel1 #bae ,disk clutch1 #adf ,distributor2 magneto1 #abd ,dixie magneto action1 #aai ,double bowl carburetor2 adjustment of1 #bah ,double opposed engine1 #be ,drive2 master gear or bull gear1 #afe ,drive2 purpose of1 #f ,drive2 worm1 #aff ,engine base1 #cj ,engine2 double opposed1 #be ,engine2 horizontal1 #be ,engine2 how power is delivered by1 #ba ,engine loses power1 #bdi ,engine misses1 #beb ,engine overheats1 #bef ,engine2 priming1 #bad ,engine2 principle of1 #i ,engine2 purpose of1 #f ,engine smokes1 #beh ,engine starts2 but stops1 #bed ,engine stops1 #bea ,engine trouble2 locating1 #bdf ,engine2 vertical1 #be ,engine will not start1 #bdf ,exhaust stroke1 #bj ,exhaust valve1 #ch ,expanding clutch1 #ade ,extra air inlet1 #fc ,firing order1 #bh ,float feed carburetor1 #gf ,force feed oiling system1 #ahf ,frame2 purpose of1 #h ,freezing2 to prevent1 #bji ,front axles2 types of1 #agb ,fuel2 dirt in the1 #bae ,fuel2 straining the1 #hi ,gas engine cycle1 #aa ,gasket1 #cj ,gasoline mixture1 #eg ,governor1 #id ,grease cup1 #aig ,grease2 when used1 #ahb ,grinding valves1 #bbi ,grounded circuit or ground return1 #abe ,heat2 action of1 #i ,heat2 effect on oil of1 #agg ,heat necessary in forming mixture1 #eh ,heating the carburetor1 #gj ,heating the mixture1 #hf ,horizontal engine1 #be ,ignition point2 changing the1 #ajc ,ignition system2 ,atwater-,kent1 #acf ,ignition system2 parts of1 #aje ,ignition2 theory of1 #ag1 #ajb ,impulse starter1 #abh ,induction and induced current1 #ajf ,inductor magneto1 #aae ,inlet stroke1 #ad ,inlet valve1 #ch ,jack shaft1 #afe ,jaw clutch change speed gear1 #aef ,k-,w magneto action1 #aae ,kerosene mixture1 #eg ,leaks of compression2 locating1 #bbh ,lean mixture1 #ed ,loading1 #fg ,lubricating systems1 #ahd ,lubrication chart2 use of1 #ahb ,lubrication2 importance of1 #age ,magnetism1 #aje ,magnet2 poles of1 #ajf ,magneto action2 ,bosch1 #aaj ,magneto action2 ,dixie1 #aai ,magneto action2 ,k-,w1 #aae ,magneto distributor1 #abd ,magneto distributor2 cleaning1 #bbb ,magneto inductor1 #aae ,magneto2 oiling a1 #bba ,magneto platinum points2 care of1 #bba ,magneto safety spark gap1 #abg ,magneto spark2 theory of1 #aje ,magneto2 theory of ,bosch1 #aaj ,magneto timer or circuit breaker1 #aaj ,magneto timing1 #bbc ,magneto trouble2 testing for1 #bbd ,manifold1 #gj ,master gear drive1 #afe ,mechanical oiler1 #aib ,mixer1 #eg ,mixing chamber1 #gj ,mixture changes with engine speed1 #fb ,mixture2 formation of1 #ec ,mixture2 gasoline and kerosene1 #eg ,mixture2 heating the1 #hf ,mixture2 heat necessary to form1 #eh ,mixture2 rich1 #ee ,mixture2 theory of1 #i ,mixture2 thin1 or lean1 #ed ,oil affected by heat1 #agg ,oil2 burning point and viscosity1 #ahb ,oil cup1 #aic ,oiler2 mechanical1 #aib ,oiling chart2 use of1 #ahb ,oiling2 importance of1 #age ,oiling systems1 #ahd ,oil pump1 #ahh ,oil2 varieties used on tractors1 #agi ,piston1 #cd ,piston pin1 #cd ,piston rings1 #cg ,piston rings2 care of1 #bbh ,plate clutch1 #adf ,poles of magnet1 #ajf ,power diagram1 #ba ,power production1 #ab ,power stroke1 #ai ,preignition1 #ef1 #hc1 #ajd ,priming the engine1 #bad ,pump feed carburetor1 #hj ,push rod1 #db ,push rod adjustment1 #bcd ,radiator1 #dh ,retard of ignition2 theory of1 #ai ,rich mixture1 #ee ,rocker arm1 #db ,safety spark gap1 #abg ,shuttle armature1 #ajg ,sliding change speed gear1 #aed ,spark coil2 principle of1 #acc ,spark coil2 vibrator1 #ach ,spark coil2 windings of1 #acd ,spark plug1 #adj ,spark plug gap1 #bbf ,spark plugs2 trouble with1 #bbe ,splash oiling system1 #ahd ,spray 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