,illu/ration3 ,,int]ior ,,( #afj-,,ton ,b4 ,,& ,o4 ,,electric ,,locomotive4 ,g5]al ,electric ,company4 ,electric ,railways ,a ,treatise on ! ,,mod]n ,,developm5t ,,( ,,electric ,,traction1 ,,includ+ ,,practical ,,in/ruction ,,9 ,,! ,,late/ ,,approv$ ,,me?ods ,,( ,,electric ,,railroad ,,equipm5t ,,& ,,op]ation ,,electric ,,railways ,by ,james ,r4 ,crava? ,we/]n ,editor 8,! ,/reet ,railway ,j\rnal0 ,,! ,,s+le-,,phase ,,electric ,,railway ,by ,h>ris ,c4 ,tr[1 ,s4,b4 ,am]ican ,in/itute ( ,electrical ,eng9e]s4 ,editor ,textbook ,dep>tm5t1 ,am]ican ,s*ool ( ,correspond5ce ,,illu/rat$ ,,*icago ,,am]ican ,,s*ool ,,( ,,correspond5ce #aijh ,copyright #aijg by ,am]ican ,s*ool ( ,correspond5ce ,ent]$ at ,/ation]s' ,hall1 ,london ,all ,rights ,res]v$ ,=eword ,9 rec5t ye>s1 su* m>vel\s advances h be5 made 9 ! eng9e]+ & sci5tific fields1 & s rapid has be5 ! evolution ( me*anical & con/ructive processes & me?ods1 t a di/9ct ne$ has be5 creat$ = a s]ies ( practical work+ guides1 ( conv5i5t size & l[ co/1 embody+ ! accumulat$ results ( exp]i5ce & ! mo/ approv$ mod]n practice along a great v>iety ( l9es4 ,to fill ?is ackn[l$g$ ne$1 is ! special purpose ( ! s]ies ( h&books to :i* ?is volume belongs4 ,9 ! prep>ation ( ?is s]ies1 x has be5 ! aim ( ! publi%]s to lay special /ress on ! practical side ( ea* subject1 z di/+ui%$ f m]e !oretical or academic discussion4 ,ea* volume is writt5 by a well-kn[n exp]t ( ackn[l$g$ au?ority 9 8 special l9e1 & is bas$ on a mo/ c>eful /udy ( practical ne$s & up-to-date me?ods z develop$ "u ! conditions ( actual practice 9 ! field1 ! %op1 ! mill1 ! p[] h\se1 ! draft+ room1 ! eng9e room1 etc4 ,^! volumes are especially adapt$ = purposes ( self-in/ruction & home /udy4 ,! utmo/ c>e has be5 us$ to br+ ! treatm5t ( ea* subject )9 ! range ( ! common und]/&+1 s t ! "w w appeal n only to ! te*nically tra9$ exp]t1 b also to ! beg9n] & ! self-taught practical man :o wi%es to keep abrea/ ( mod]n progress4 ,! language is simple & cle>2 heavy te*nical t]ms & ! =mul ( ! high] ma!matics h be5 avoid$1 yet )\t sacrific+ any ( ! requirem5ts ( practical in/ruction2 ! arrangem5t ( matt] is su* z to c>ry ! read] along by easy /eps to complete ma/]y ( ea* subject2 frequ5t examples = practice are giv51 to enable ! read] to te/ 8 k & make x a p]man5t possession2 & ! illu/rations are select$ ) ! greate/ c>e to supplem5t & make cle> ! ref]5ces 9 ! text4 ,! me?od adopt$ 9 ! prep>ation ( ^! volumes is t :i* ! ,am]ican ,s*ool ( ,correspond5ce has develop$ & employ$ s successfully = _m ye>s4 ,x is n an exp]im5t1 b has /ood ! sev]e/ ( all te/s--t ( practical use--:i* has demon/rat$ x to be ! be/ me?od yet devis$ = ! education ( ! busy work+ man4 ,= purposes ( ready ref]5ce & timely in=mation :5 ne$$1 x is believ$ t ?is s]ies ( h&books w be f\nd to meet e requirem5t4 ,illu/ration ,table ( ,cont5ts ,c> ,equipm5t ,page #c ,classification ( ,electric ,railways -- ,motors -- ,armature ,w9d+ -- ,armature & ,field ,coils -- ,armature & ,motor ,leads -- ,bru%es & ,bru%-,hold]s -- ,ge>+ -- ,lubrication -- ,be>+s -- ,motor ,susp5sion -- ,electric ,locomotive ,motors -- ,controll]s -- ,rheo/at & ,s]ies-,p>allel ,control -- ,controll] ,con/ruction -- ,multiple-,unit ,control 7,sprague1 ,g5]al ,electric1 ,we/+h\se ,electro-,pneumatic7 -- ,c>-,heat]s -- ,c> ,wir+ -- ,electric-,c> ,accessories 7,canopy ,swit*es2 ,circuit-,break]s2 ,fuses2 ,lightn+ ,arre/]s2 ,lamp ,circuits2 ,trolley-,base2 ,trolley-,poles1 ,:eels1 & ,h>p2 ,contact ,%oes2 ,sleet ,:eels7 -- ,s+le ,trucks -- ,swivel ,trucks -- ,maximum-,traction ,trucks -- ,c> ,:eels -- ,brake ,rigg+ -- ,air-,brakes 7,compressor1 ,automatic ,gov]nor1 ,/orage ,tanks7 -- ,mom5tum ,brakes -- ,g4 ,e4 ,electric ,brake -- ,we/+h\se ,electromagnetic ,brake -- ,track ,brakes -- ,motors z ,em]g5cy ,brakes -- ,brake ,%oes -- ,track ,s&]s -- ,drawb>s & ,c\pl]s4 ,c> ,con/ruction ,page #fg ,c> ,bodies -- ,/eel ,c> ,fram+ -- ,c> ,weights -- ,c> ,pa9t+4 ,l9e ,con/ruction ,page #gc ,ov]head ,con/ruction -- ,trolley-,wire -- ,clamps & ,e>s -- ,span ,wires -- ,brackets -- ,fe$]s -- ,section ,insulators -- ,high-,t5sion ,l9es -- ,?ird-,rail ,sy/em -- ,conduit ,sy/ems -- ,contact ,pl[ -- ,curr5t ,leakage -- ,track ,con/ruction -- ,gird] ,rail -- ,trilby ,groove ,rail -- ,%anghai ,t-,rail -- ,common ,t-,rail -- ,track ,support -- ,balla/ -- ,jo9ts 7,weld$1 ,ca/-,weld$1 ,electrically ,weld$1 ,!rmit-,weld$7 -- ,bond+ & ,return ,circuits -- ,fe$] ,sy/ems -- ,block ,signals -- ,electrolysis & ,its ,prev5tion4 ,p[] ,supply & ,di/ribution ,page #ih ,direct-,curr5t ,fe$+ -- ,boo/] ,fe$+ -- ,alt]nat+-,curr5t ,transmission -- ,int]urban ,di/ribution -- ,p[]-,h\se ,location -- ,alt]nat+-,curr5t ,g5]ators -- ,d\ble-,curr5t ,g5]ators -- ,g5]al ,plan ( ,p[] ,/ations -- ,swit*bo>ds -- ,g5]ator ,d4 ,c4 ,panels -- ,/>t+ ,up a ,g5]ator -- ,fe$] ,panel -- ,alt]nat+-,curr5t ,swit*bo>ds -- ,high-,t5sion ,oil-,swit*es -- ,/orage ,batt]ies 9 ,/ations -- ,?ree-,phase ,motors -- ,s+le-,phase ,motors4 ,op]ation ( ,electric ,railways ,page #aae ,p[] ,tak5 by ,c>s -- ,road ,te/s ( ,c>s -- ,economy 9 ,p[] -- ,slid+ & ,sp9n+ ,:eels -- ,te/+ = ,faults -- ,bond ,te/+ -- ,motor-,coil ,te/+ -- ,gr\nds -- ,burn-,outs -- ,defects ( ,armature ,w9d+s -- ,sp>k+ at ,commutator -- ,failure ( ,c> to ,/>t -- ,op5-,circuit ,te/s -- ,%ort-,circuit ,te/s -- ,fuse-,bl[s -- ,armature & ,field ,te/s = ,gr\nds -- ,rev]s$ ,fields -- ,c> ,repair ,%ops4 ,! ,s+le-,phase ,electric ,railway ,page #acg ,commutator ,type ,s+le-,phase ,motor -- ,advantages & ,disadvantages ( ,s+le-,phase ,sy/em -- ,l9es 9 ,op]ation4 ,index ,page #adi ,illu/ration3 ,,heavy-,,duty ,,cross-,,comp\nd ,,cond5s+ ,,eng9e1 ,,direct ,,connect$ ,,to #a1ejj ,k4,w4 ,,railway ,,g5]ator4 ,/4 ,l\is ,transit ,company's ,p[] ,h\se4 ,fulton ,iron ,works4 ,,electric ,,railways4 ,,"p ,i4 ,! g5]al "n 8electric railway0 is appli$ to all railways employ+ electric motors to supply p[] = ! propulsion ( c>s4 ,on all electric railways 9 comm]cial use to-day1 ! electric motor is us$ to furni% p[] to ! driv+ :eels ( ! c> or locomotive1 ! electric motor be+ ! mo/ effici5t kn[n means ( trans=m+ electrical into me*anical en]gy4 ,electric railways are usually classifi$ accord+ to ! me?ods by :i* curr5t is suppli$ to ! mov+ c>4 ,?us1 :]e an ov]head trolley wire is us$1 z on ! great majority ( electric railways1 ! t]m trolley road is appli$4 ,:]e an insulat$ /eel rail is laid alongside ! track rail = supply+ curr5t1 z on ! 8elevat$0 roads 9 ,am]ica & on a few int]urban roads1 ! t]m ?ird-rail road is us$4 ,:]e1 z on ! /reet railways ( a few l>ge cities1 ! conductors are plac$ 9 a conduit und]nea? ! surface ( ! /reet1 & curr5t is tak5 by means ( a pl[ or %oe runn+ 9 ! conduit1 ! "n electric-conduit railway is mo/ commonly appli$4 ,!re are also a few sy/ems us+ conductors buri$ b5ea? ! pavem5t1 & hav+ contact buttons or sections ( conductor rail on ! /reet surface1 :i* sections are suppli$ ) curr5t by automatic electromagnetic swit*+ app>atus z ! c> passes1 b :i* are normally dead & h>mless4 ,! ov]head trolley & ! ?ird-rail sy/ems are by f> ! mo/ common4 ,a fur!r g5]al classification ( electric railways has rec5tly be5 made because ( ! introduction ( alt]nat+-curr5t railway motors4 ,! great majority ( electric railways employ direct-curr5t motors4 ,:]e alt]nat+-curr5t motors are us$1 ! road is spok5 ( z "o us+ s+le-phase alt]nat+-curr5t motors or ?ree-phase alt]nat+-curr5t motors1 z ! case may be4 ,all electric railway sy/ems 9 comm]cial use are op]at$ on an approximately con/ant pot5tial or voltage1 & ! v>i\s electric motor c>s op]at+ on ! sy/em are connect$ across ! l9es 9 p>allel4 ,! mo/ common practice is to utilize ! rails & gr\nd z "o side ( ! circuit1 & ! ov]head trolley wire or 8?ird rail0 z ! o!r side1 z 9 ,fig4 #a4 ,! trolley wire or ?ird rail is1 ( c\rse1 ?or\ghly insulat$ f ! gr\nd4 ,! positive poles ( ! g5]ators at ! p[] h\se are usually connect$ to ! trolley wire1 & ! negative poles to ! rails & gr\nd4 ,! v>i\s electric motor c>s1 be+ connect$ 9 p>allel or multiple betwe5 ! trolley wire & ! gr\nd1 draw :atev] curr5t is necess>y = _! op]ation4 ,:]e ! conduit sy/em is us$1 bo? sides ( ! circuit are insulat$ f ! gr\nd1 & ! contact %oe or pl[ collects curr5t f two conduct+ rails 9 ! conduit1 "o ( ^! conduct+ rails be+ positive & ! o!r negative4 ,a d\ble-trolley sy/em is also 9 use to a limit$ ext5t4 ,9 ?is sy/em1 bo? ! positive & ! negative sides ( ! circuit are insulat$ f ! gr\nd1 "o trolley wire be+ positive & ! o!r negative4 ,illu/ration3 ,fig4 #a4 ,illu/ration3 ,fig4 #b4 ,railway ,motor4 ,fur!r discussion ( ! matt]s j outl9$ w be tak5 up 9 ! succe$+ pages4 ,,c> ,,equipm5t4 ,,motors4 ,! voltage mo/ commonly employ$ by electric railways is #ejj to #fjj2 & ! motors are #ejj-volt direct-curr5t s]ies-w\nd motors1 design$ especially = railway s]vice4 ,! electric railway motor mu/ be du/pro( & wat]pro( because ( ! position x occupies "u ! c>4 ,= ?is reason electric railway motors are made 9 ! =m ( a /eel case 7,fig4 #b71 :i* entirely surr\nds ! field-magnet poles & takes ! place ( ! yokes or frames t support ! fields on /ation>y motors4 ,ca/ /eel is ! mat]ial n[ usually employ$ = railway motor cases & fields1 on acc\nt ( its me*anical /r5g? & its high magnetic p]meability4 ,! f\r poles project inw>dly f ! case1 z se5 9 ! op5 motor case1 ,fig4 #c1 :i* is t ( a ,we/+h\se ,no4 #fi motor4 ,illu/ration3 ,fig4 #c4 ,railway ,motor4 ,upp] ,field ,rais$4 ,railway motors h usually f\r poles because ?is p]mits ( a symmetrical & economical arrangem5t ( mat]ial ar\nd ! armature1 & h5ce p]mits ! motor to be plac$ 9 ! small space available on ! c> truck4 ,two-pole motors h be5 us$ 9 ! pa/1 b !y 7 n z compact z ! f\r-pole type4 ,*>act]i/ics ( ,railway ,motors4 ,! curve %eet1 ,fig4 #d1 = ! ,we/+h\se ,no4 #fi motor repres5ts 9 g5]al ! *>act]i/ics ( all direct-curr5t railway motors4 ,! figures = ea* curve are f\nd ) names correspond+ to ! curve to :i* !y apply1 at ea* side repres5t$ by v]tical di/ance on ! %eet4 ,! amp]es1 repres5t$ by ! horizontal di/ance1 are m>k$ at ! bottom1 & apply 9 common to all ! curves4 ,! tractive ef=t at diff]5t curr5t consumption is repres5t$ by a l9e curv+ upw>ds some:at4 ,?is %[s t ! tractive ef=t increases1 9 a proportion great] ?an directly1 z ! curr5t increases4 ,! torque requir$ 9 />t+ may be _m times great] ?an t necess>y to ma9ta9 ! c> at full spe$4 ,! s]ies-w\nd motor1 !re=e1 furni%es ?is great />t+ torque m economically ?an a %unt-w\nd motor ! torque ( :i* is proportion$ to ! curr5t4 ,?is feature ( ! s]ies-w\nd motor makes x especially adapt$ to /reet railway "w4 ,illu/ration3 ,,we/+h\se ,no4 #fi ,,railway ,,motor #ejj ,,volts ,,ge> ,,ratio1 #ad ,,to #fh4 ,,:eels1 #cc ,,cont9u\s ,,capacity1 #be ,,amp]es ,,at #cjj ,,volts1 ,,or #bc ,,amp]es ,,at #djj ,,volts4 ,fig4 #d4 ,*>act]i/ic ,curves ( ,railway ,motor4 ,! effici5cy curve %[s ! motor to h an effici5cy ( ab\t #hc p] c5t ) ge>s4 ,mu* o!r in=mation may be obta9$ by a prop] /udy ( ! curves4 ,! fields are work$ ne> ! po9t ( magnetic saturation4 ,?is economizes metal & space & is also an advantage because ( ! fact t :5 s work$ ! armature reactions h v little effect on ! fields4 ,! neutral po9ts betwe5 fields are consequ5tly %ift$ v little & x is !re=e n necess>y to %ift ! bru%es :5 ! motor is rev]s$4 ,illu/ration3 ,fig4 #e4 ,armature ,w9d+4 ,g5]al ,data on ,/reet ,railway ,motors4 ,armature ,w9d+4 ,! armature w9d+ is :at is commonly kn[n z ! s]ies or wave w9d+1 %[n develop$ 9 ! pap] on ,direct-,curr5t ,dynamos4 ,?is w9d+ is %[n 9 ,fig4 #e1 :i* is an end view ( an armature & commutator4 ,9 ! figure1 h[ev]1 ! armature is %[n ) a mu* small] numb] ( slots ?an a railway armature %\ld h 9 practice4 ,"o reason = ! employm5t ( ! wave or s]ies w9d+ on railway motor armatures1 is t ) ?is w9d+ no cross-connections are necess>y :5 only two bru%es are us$1 & ^! two bru%es may be plac$ #ij ap>t 9 a conv5i5t & accessible position4 ,ano!r reason is t ! curr5t1 9 fl[+ f "o bru% on ! commutator to ano!r1 mu/ always pass ?r\gh ! magnetic field ( all f\r ( ! motor poles4 ,?is makes x impossible = any unbalanc+ ( ! magnetic circuit to cause m curr5t to fl[ ?r\gh "o portion ( ! armature ?an is fl[+ ?r\gh ano!r portion4 ,9 a railway motor x has be5 f\nd q possible to h "o pole or pair ( poles ex]t+ a great] magnetic attraction on ! armature ?an ano!r pair1 ow+ to diff]5ces 9 ! iron & diff]5ces 9 ! cle>ance betwe5 ! armature & pole pieces1 :i* diff]5ces cause m magnetic l9es ( =ce to fl[ f "s pole pieces ?an f o!rs4 ,) ! lap-armature or ! r+-armature w9d+1 s9ce ! v>i\s portions ( ! armature "u diff]5t poles are 9 p>allel ) "o ano!r1 any diff]5ce 9 ! magnetic flux betwe5 diff]5t poles w cause a diff]5t am\nt ( curr5t to fl[ 9 ! v>i\s pa?s ?r\gh ! armature4 ,type ( ,horse ,amp- ,spe$,total ,slots4,cond- ,commu- ,weight ,armature ,ge>s ,commutator ,p9ion ,dia- ,l5g?4 ,motor4 ,p[]4eres4,full ,field uctorstator complete,complete4 & ,be>+4 ,be>+4 met] ,load4,turns4 p] ,b>s4 ) ,cas+4 ,arma- slot ,ge>s4 ,in*es4 ,in*es4 ture4 ---------------------------------------- ---------------------------------------- --------------------- ,g5]al ,electric #ea #hb #fdj #ef #cg #ab #aaa #chge #iec #cch #c #e #c #h #af #aj #eb #bg #fdj #aee4e #bi #bd #hg #agbe #ceg #bfe #b #f #b #g #aa #i #eg #eb #dgj #aaj #cc #ah #ii #bigb #gjd #cdj #b #f #c #h #ad #ab #ee #afj #dg #f #ada #edae #aeej #dij #c #g #c #aa #fg #dj #aaj #cg #ah #aaa #bche #eie #che #b #f #c #h #ed #be #aae #ahca #cie #bhe #b #f #b #g #gd #fe #aac #gj4e #cecd #hde #dae #c #f #c #h ---------------------------------------- ---------------------------------------- --------------------- ---------------------------------------- ---------------------------------------- --------------------- ,we/+- h\se #fh #dj #ee #ab #aji #bbhj #eje #ccj #b #f #c #g #ad #h #fi #cj #ce #aje #aiej #che #ccj #b #f #b #g #ac #f #gf #ge #ci #aag #chdj #eje #hfj #c #h #c #i #af #ef #ee #ci #aag #cjjj #cae #gbj #c #g #c #h #ad #ab #ej;c #aej #add #ee #f #aae #eeej #aejj #di #ce #aad #ei #aag #aibe #dch #cbg #b #f #b #g #ac #f ---------------------------------------- ---------------------------------------- --------------------- ,by ref]5ce to ! w9d+ diagram giv5 9 ,fig4 #e1 x may be not$ t a complete circuit ?r\gh two coils ends at ! segm5t adjac5t to ! "o f :i* ! />t 0 made4 ,x may also be not$ 9 ! table ( motor data t all ( ! armatures h an odd numb] ( segm5ts & an odd numb] ( slots4 ,x is absolutely necess>y 9 a wave w9d+ to h an odd numb] ( segm5ts4 ,o!rwise ! w9d+ c\ld n be made symmetrical & ! circuit ?r\gh two coils be made to return to a segm5t adjac5t to t f :i* ! />t 0 made4 ,) equal spac+ betwe5 ! top & bottom leads ( ! two coils1 an ev5 numb] ( segm5ts w\ld make ! circuit return ei!r on ! segm5t f :i* ! />t 0 made or two segm5ts f x4 ,! fir/ drum-w\nd /reet railway motor armatures _h z _m slots 9 ! armature z !re 7 coils & segm5ts4 ,! great numb] ( slots necess>ily made ! tee? v ?9 & consequ5tly weak4 ,?is is v objectionable z sometimes ! armature be>+s we> away1 all[+ ! face ( ! armature to drag on ! pole pieces & ?9 tee? are b5t out ( %ape4 ,armatures are n[ almo/ entirely con/ruct$ ) ei!r two or ?ree coils to a slot4 ,:5 two coils are us$ 9 ea* slot ) an odd numb] ( slots an ev5 numb] ( coils results4 ,if ^! 7 all connect$ to ! commutator an ev5 numb] ( segm5ts w\ld be necess>y4 ,z ?is is n possible ) a wave w9d+1 "o ( ! coils is 8cut out40 ,! ends are cut %ort & tap$ & x is t]m$ a 8dead0 coil4 ,?is makes ! w9d+ some:at unsymmetrical1 all ! coils n be>+ ! same angul> relation to ! commutator segm5ts to :i* !y are connect$4 ,?is diff]5ce is1 h[ev]1 n great en\gh to affect ! op]ation ( ! ma*9e4 ,! ,we/+h\se #di motor is an example ( an armature ) a dead coil4 ,by ref]5ce to ! table ( motor data x w be se5 t ?is armature has #ei slots4 ,two coils 9 ea* slot w\ld make #aah coils4 ,"o ( ^!1 h[ev]1 is cut out1 giv+ #aag segm5ts4 ,cutt+ out a coil c be avoid$ by putt+ ?ree coils 9 ea* slot4 ,an odd numb] ( coils results !n no matt] :at ! numb] ( slots may be4 ,9 ! majority ( examples giv5 9 ! table !re are ?ree times z _m segm5ts z slots4 ,! sides ( ! slots ( mod]n /reet railway armatures are /raight4 ,! coils are prev5t$ f fly+ out by b&s ( wire ext5d+ ov] ! tops ( ! coils ar\nd ! armature4 ,/eel or silicon bronze wire ( ab\t ,no4 #ad gauge is us$4 ,recesses are made 9 ! armature tee? = ! reception ( ^! b&s s t ! wire :5 w\nd w come flu% ) ! face ( ! armature4 ,! b&s are usually to #a in*es wide4 ,! wires are well sold]$ toge!r to secure !m 9 place4 ,"o tr\ble exp]i5c$ ) armatures is ! slipp+ (f ( ^! b&s4 ,! heat$ armature exp&s & /ret*es !m4 ,:5 ! armature cools ! b&s are loose & !n (t5 slip (f4 ,:5 !y d s ! coils fly out by c5trifugal =ce1 /rike ! pole pieces & gr\nd ! motor4 ,illu/ration3 ,fig4 #f4 ,armature ,coil4 ,armature ,coils4 ,railway motor armatures are to-day univ]sally con/ruct$ ) =m-w\nd coils1 :i* are w\nd on a =m ( prop] %ape & c>efully insulat$ be=e be+ plac$ 9 ! armature4 ,! coils ( ! small] motors 7^? up to #dj or #ej horsep[]7 are usually w\nd ) r\nd wire4 ,! cotton cov]+ ( ! wire is dep5d$ ^u = insulation4 ,to /r5g!n ?is1 h[ev]1 ! coils aft] be+ w\nd are imm]s$ 9 an insulat+ comp\nd & !n bak$ 9 an ov54 ,! :ole coil is usually wrapp$ ) insulat+ tape 7,see ,fig4 #f74 ,! armatures ( l>g] motors h coils made ( copp] b>s4 ,mica is (t5 plac$ betwe5 & ar\nd ! b>s = insulation1 ?\gh oil$ l95 clo? tape cut bias is also employ$1 especially 9 repair "w4 ,field ,coils4 ,field coils are s con/ruct$ t !y may be readily remov$ %\ld !y become gr\nd$ or %ort-circuit$4 ,"s mak]s w9d !m on a brass %ell or =m :i* is slipp$ ov] ! pole piece4 ,9 "s motors ! field coils are compos$ ( copp] ribbon1 w\nd b>e1 ) ribbons ( insulat+ mat]ial betwe5 ! turns4 ,field coils ( wire = ! small] motors1 if n w\nd on %ells1 are w\nd on =ms & be=e completion are tap$ 9 su* a mann] t !y w hold _! %ape )\t be+ enclos$ 9 a spool4 ,! t]m9als are br\ght out :]e !y w be ( easy access :5 ! field is 9 place 7,see ,fig4 #g74 ,illu/ration3 ,fig4 #g4 ,field ,coil4 ,armature ,leads4 ,9 ,fig4 #c is se5 a complet$ armature 9 ! motor cas+ ( a ,we/+h\se ,no4 #fi motor4 ,s9ce ! motors are f\r-pole1 ! two sides ( any "o coil occupy slots #ij ap>t 9 ! armature coil1 z indicat$ 9 ,fig4 #e4 ,! ends ( ! coils are connect$ to commutator b>s #ahj ap>t4 ,! relative position ( ! commutator connections ( any armature coil c1 ( c\rse1 be v>i$ s z to br+ ! bru%es 9 ! mo/ conv5i5t position 9 ! motor cas+4 ,bru%es are always ( c>bon1 & are plac$ :]e !y c be easily rea*$ f ! op5+ 9 ! motor cas+ ov] ! commutator4 ,motor ,leads4 ,! rev]s+ ( ! curr5t ?r\gh ! armature1 indep5d5t ( ! field curr5t1 to secure rev]sal ( direction ( rotation ( ! armature1 makes x necess>y t f\r wires ent] ! motor4 ,! portions ( ^! wires connect$ p]man5tly to ! motor are t]m$ ! motor leads because !y 8lead out0 ! curr5t4 ,sometimes an ord9>y two-way connector is us$ 9 connect+ ^! leads to ! wires ( ! cable1 b (t5 a jack-knife connector is employ$ to facilitate connect+ & disconnect+4 ,consid]able difficulty has be5 exp]i5c$ by ! we>+ away ( ! insulation ( ! leads :]e !y re/ on ! motor %ell4 ,to avoid ?is !re has rec5tly come into use a lead protect$ by a spiral metal cov]+4 ,bru%es4 ,t ! motor may op]ate 9 ei!r direction equally well1 ! c>bon bru%es are plac$ radially or ne>ly s4 ,no provision is made = %ift+ _! position relative to ! fields4 ,!y usually occupy a position equidi/ant betwe5 pole tips4 ,! common types are ei!r or -in* ?ick & f #b to #d in*es wide4 ,illu/ration3 ,fig4 #h4 ,bru% ,hold]4 ,bru% ,hold]s4 ,two me?ods ( secur+ ! bru% hold]s are employ$4 ,9 ,fig4 #c1 ! bru% hold]s may be se5 to be secur$ 9 position by be+ bolt$ ?r\gh ! end ( ! motor %ell4 ,fig4 #h %[s ! bru%es m\nt$ on a yoke :i* is secur$ to ! motor %ell4 ,! yoke is ( wood & provides ! necess>y insulation4 ,:]e ! hold]s are fa/5$ directly to ! %ell a block & wa%]s ( vulcabe/on or o!r insulat+ mat]ial int]v5e to furni% ! insulation betwe5 ! %ell & ! hold]4 ,9 practice ! greate/ difficulty exp]i5c$ ) bru% hold]s is prev5t+ !m f becom+ gr\nd$ by dirt & c>bon du/ :i* collects on ! insulation4 ,op5+ ,cases = ,inspection4 ,accessibility = inspection & repairs is ess5tial 9 all railway motors4 ,a lid is always provid$ directly ov] ! commutator to facilitate inspection ( ! commutator & bru%es4 ,to op5 up ! motor cas+ = m ext5sive inspection or repairs1 ?ree g5]al s*emes are employ$4 ,"o is to h ! l[] half ( ! cas+ sw+ d[nw>d on a h+e z 9 ,fig4 #i1 :i* illu/rates ! ,we/+h\se ,no4 #ch ,b motor4 ,! armature may be plac$ ei!r 9 ! l[] half1 z %[n 9 ,fig4 #i1 or 9 ! upp] half4 ,:5 a motor ( ?is type is to be op5$ ! c> is run ov] a pit1 & ! repair m5 "w entirely f bel[4 ,(t5 ! h+e p9s are remov$ & ! l[] %ell conta9+ ! armature is dropp$ d[n by means ( a jack plac$ und]nea?4 ,two h&holes are usually provid$ 9 ! bottom %ell = obs]v+ ! cle>ance betwe5 ! armature & ! pole pieces & also = remov+ dirt t may collect 9 ! bottom ( ! %ell4 ,ano!r s*eme is to h motors op5 f ! top1 ei!r by h++ ! upp] "p ( ! motor cas+1 z 9 ,fig4 #c1 or by hav+ ! top "p ( ! cas+ lift (f4 ,:]e ?is =m ( motor is us$1 ! c> body is hoi/$ cle> ( ! truck1 & ! trucks are run out f "u ! c> body be=e "w is done on ! motors4 ,9 ?is case1 all ! "w c be done f above )\t ! use ( pits4 ,illu/ration3 ,fig4 #i4 ,railway ,motor4 ,l[] ,half ( ,cas+ ,swung ,d[n4 ,a ?ird design is ! box-frame motor cas+1 f :i* ! armature c be remov$ endwise only4 ,su* an arrangem5t is %[n 9 ,fig4 #aj1 :i* is a view ( a ,no4 #ff motor ( ! ,g5]al ,electric ,company4 ,9 ?is motor a suffici5tly l>ge op5+ is provid$ 9 ! ends ( ! motor cas+ to p]mit ( ! armature be+ remov$ endwise4 ,a plate or head1 :i* accurately fits into ?is op5+1 c>ries ! armature be>+4 ,9 remov+ armatures f motors ( ?is k9d1 ! usual me?od is to take ! motor out ( ! trucks & /& x on end ) ! p9ion up4 ,! bolts be+ remov$ f ! end plate1 ! armature c !n be hoi/$ out ( ! case by means ( a special hook atta*$ to ! p9ion4 ,ano!r plan t has be5 us$ 9 remov+ armatures f su* motors1 is to place ! motor 9 an app>atus :]e ! armature %aft c be held betwe5 c5t]s1 z 9 a l>ge la!4 ,! motor cas+ is !n mov$ along 9 a direction p>allel to ! armature %aft1 until ! armature is expos$4 ,?is latt] box-frame type ( motor is v compact2 a /rong] cas+ c be made = a giv5 weight & space ?an if x 7 divid$ horizontally4 ,moreov]1 ! magnetic circuit _c be di/urb$ by imp]fect contact betwe5 two p>ts ( ! cas+4 ,:]e ?is type ( motor is us$1 ! be>+s project inw>d "u ! commutator & armature1 ?us gett+ long be>+s ) a %ort motor1 :i* is important :]e ! room is limit$1 z1 = example1 9 ! case ( a l>ge motor m\nt$ on a /&>d-gauge truck4 ,illu/ration3 ,fig4 #aj4 ,box-,frame ,motor4 ,ge>+4 ,9 mo/ cases1 spur ge>+ is us$ to transmit p[] f ! armature %aft to ! c> axle1 al?\gh a few motors ) armatures m\nt$ directly on ! c> axle are 9 use4 ,v>i\s ge>+s o!r ?an ! simple spur ge> h be5 tri$1 su* z worm ge>s1 *a9 & bevel ge>s4 ,practically all h be5 ab&on$ 9 favor ( ! s+le-r$uction spur ge>+1 :i* is ! mo/ satisfactory f ! /&po9t ( we> & effici5cy4 ,?is ge>+ is %[n 9 ,figs4 #c & #i4 ,! ge>+ is cov]$ ) a ge> case 7,fig4 #i71 :i* is usually ( /eel1 ?\gh ge> cases ( ?9 %eet metal & wood are sometimes us$4 ,a solid ge> is %[n 9 ,fig4 #aa1 & a split ge> 9 ,fig4 #ab4 ,! ge> ratios 9 common use v>y f #e to #a to #b to #a1 ! l>g] ratio be+ common on ! small] motors4 ,a ratio (t5 us$ on motors ( #cj to #ej horsep[] is #d4gh to #a1 ! ge> hav+ #fg tee?1 ! p9ion #ad tee?4 ,/reet c> :eels are usually #cc in*es 9 diamet]4 ,?is makes necess>y #fab revolutions p] mile4 ,) a ge> ratio ( #d4gh ! armature revolves #b1ibe times p] mile4 ,at #ae miles p] h\r1 ?is gives #gca r4p4m4 ,illu/ration3 ,fig4 #aa4 ,solid ,ge>4 ,illu/ration3 ,fig4 #ab4 ,split ,ge>4 ,lubrication4 ,! lubrication ( railway motors 0 = a numb] ( ye>s c>ri$ on almo/ exclusively ) grease1 :i* x 0 cu/om>y to place 9 ! ge> cas+ & 9 grease boxes ov] ! armature & c>-axle be>+s4 ,grease becomes mo/ effici5t z a lubricant only :5 ! be>+ is heat$ suffici5tly to make ! grease run l oil4 ,oil is n[ be+ us$ to a consid]able ext5t1 especially = l>g] motors4 ,x is f$ to ! be>+s by v>i\s devices t all[ a v sl[ fe$1 su* z wicks & lubricators adju/$ to pass a small am\nt ( oil p] h\r4 ,be>+s4 ,railway motor be>+s are usually ( ,babbitt metal1 :i* metal is ca/ into a /eel %ell4 ,?is %ell fits into receptacles 9 ! motor cas+1 :i* c be se5 9 ,figs4 #c & #i4 ,a /eel %ell is us$ s t ! worn-out be>+s c be easily r5ew$ & ! %ells tak5 to a ,babbitt melt+ furnace to h new ,babbitt p\r$ into !m4 ,! motor has two sets ( be>+s1 ^? = ! armature & ^? = ! axle ^u :i* ! motor is m\nt$4 ,! axle be>+s are always split diametrically to avoid remov+ a :eel :5 a be>+ is replac$4 ,on ! lat] designs ( motors ^! are ( brass1 no ,babbitt metal be+ us$4 ,! armature be>+s are di/+ui%$ by ! t]ms 8ge> end0 & 8commutator end0 be>+s4 ,! ge> end be>+ is usually ( l>g] diamet] & ( great] l5g? because ( ! ?ru/ ( ! ge>s x mu/ take 9 addition to ! weight ( ! armature4 ,?is be>+ is split s t x may be remov$ & replac$ )\t ! removal ( ! ge>4 ,! commutator end be>+ is 9 "o piece4 ,armature be>+s are %[n 9 ,fig4 #ac4 ,illu/ration3 ,fig4 #ac4 ,armature ,be>+s4 ,motor ,susp5sion4 ,two me?ods ( susp5d+ motors flexibly on trucks are 9 common use4 ,t end ( ! motor :i* has be>+s on ! c> axle _c1 ( c\rse1 be flexibly susp5d$ ) reg>d to ! axle2 b ! o!r end ( ! motor c be plac$ on spr+s1 or re/ on a b> support$ on spr+s1 z %[n 9 ,fig4 #ad4 ,?is susp5sion is commonly call$ nose susp5sion4 ,in/ead ( hav+ a special b> & special spr+s = ! nose ( ! motor1 ! nose may re/ ^u "s "p ( ! truck t is c>ri$ ^u spr+s4 ,?us1 on ! ,m4 ,c4 ,b4 type ( swivel truck1 ! nose usually re/s on ! truck bol/]1 & ?us gets ! b5efit bo? ( ! bol/] spr+s & ( ! equaliz] spr+s ( ! truck4 ,ano!r g5]al plan ( susp5sion is t kn[n 9 "o =m z cradle susp5sion1 & 9 ano!r =m z side-b> susp5sion4 ,a side-b> susp5sion is %[n 9 ,fig4 #ae4 ,"h a l>g] p]c5tage ( ! weight ( ! motor is evid5tly tak5 by ! spr+s ?an 9 ! case ( nose susp5sion4 ,x is desirable to relieve ! c> axle ( z mu* dead weight z possible4 ,by dead weight is meant weight re/+ ^u x )\t ! int]v5tion ( spr+s4 ,illu/ration3 ,fig4 #ad4 ,nose ,susp5sion4 ,illu/ration3 ,fig4 #ae4 ,side-b> ,susp5sion4 ,motors ( ! ,new ,york ,c5tral ,electric ,locomotive4 ,^! motors are a radical dep>ture f ! usual type ( railway motors4 ,! locomotive on :i* !y are m\nt$ has f\r driv+ axles1 ^u ea* ( :i* is m\nt$ an armature1 direct1 no ge>s be+ us$1 ,figs4 #af & #ag4 ,! motors are rem>kable = ?ree special features3 ,! me?od ( m\nt+ ! armature1 ! %ape ( ! pole pieces1 & ! pa? ( ! magnetic flux4 ,illu/ration3 ,fig4 #af4 ,longitud9al ,section ( ,new ,york ,c5tral ,locomotive4 ,illu/ration3 #ie ,,ton ,,electric ,,locomotive ,,= ,,new ,,york ,,c5tral ,,railroad4 ,g5]al ,electric ,company4 ,! m\nt+ ( ! armature ^u ! driv+ axle & ! motor fields on ! truck frame makes x necess>y to h flat pole pieces 9 ord] t ! armature may play up & d[n z ! j\rnal box & axle slide 9 ! guides ( ! truck frame4 ,! %ape ( ! pole pieces may be obs]v$ 9 ! draw+ ,fig4 #af4 ,:5 9 ! c5tral position !re is a -in* air gap betwe5 ! armature & pole pieces4 ,! magnetic flux is cont9u\s ?r\gh ! fields ( all f\r ( ! motors4 ,x returns ?r\gh ! ca/ /eel side frames ( ! truck & two b>s plac$ 9 ! pa?4 ,! bru% hold]s are s m\nt$ t ! bru%es occupy a fix$ position relative to ! armature4 ,! armature is remov$ by l[]+ x ) ! :eels & axle ^u :i* x is m\nt$4 ,?is c be done )\t di/urb+ ! fields ( ! motor4 ,,controll]s4 ,9 an ord9>y electric c>1 curr5t is tak5 f ! wire ?r\gh ! trolley :eel & pole1 & is fir/ l$ f ! trolley base ?r\gh ov]head swit*es or a circuit break]1 & !n to ! controll]1 f :i* x passes ?r\gh ! motors & !nce ?r\gh ! motor frames1 c> truck1 & :eels to ! rails & gr\nd4 ,if ! c> is design$ to be op]at$ f ei!r end1 an ov]head swit* or circuit break] is plac$ ov] ea* plat=m ( ! c> s t curr5t c in/antly be cut (f entirely f ! controll]s by ?r[+ ! swit* or circuit break] at ei!r end ( ! c>4 ,illu/ration3 ,fig4 #ag4 ,armature ,axle & ,:eels4 ,! light+ circuit is run f ! trolley base indep5d5tly ( ! motor circuit1 & has its own swit* & fuse box4 ,curr5t = ! lights is tak5 f ! trolley circuit be=e x rea*es ! ma9 swit*es or circuit break]s4 ,curr5t = electric heat]s1 if su* are us$1 is likewise tak5 f a sep>ate circuit4 ,on a #ejj-volt sy/em five #ajj-volt lamps are usually connect$ 9 s]ies = c> light+4 ,z _m multiples ( five c be employ$ z are necess>y to light ! c>4 ,rheo/at ,control4 ,! simple/ =m ( controll] is t employ$ :]e only "o motor is us$ on a c>4 ,a rheo/at is plac$ 9 s]ies ) ! motor :5 />t$1 j z on a /ation>y motor2 & ! function ( ! controll] is to %ort-circuit ?is resi/ance gradually until x is entirely cut out & ! motor op]ates ) ! full voltage4 ,! controll] also has a rev]s+ swit* by means ( :i* ! relative connections ( ! armature & fields are rev]s$1 :i*1 ( c\rse1 *anges ! direction ( rotation ( ! motor armature4 ,su* a simple equipm5t z ?is1 h[ev]1 is r>ely to be f\nd 9 practice4 ,s]ies-,p>allel ,control4 ,s+le-truck c>s usually h two motors1 "o on ea* axle2 & on su* c>s a s]ies-p>allel controll] is ! k9d usually employ$4 ,diagrams ( connections on ! v>i\s po9ts ( a s]ies-p>allel controll] 7,type ,k#f7 ( ! ,g5]al ,electric ,company1 are giv5 9 ,fig4 #ah4 ,illu/ration3 ,fig4 #ah4 ,diagram ( ,k#f ,controll] ,comb9ations4 ,f ^! diagrams x is se5 t ! motors are fir/ op]at$ 9 s]ies until all ! resi/ance is %ort-circuit$ by ! controll]4 ,:5 ?is has occurr$1 ! c>s are runn+ at ab\t half spe$4 ,! next po9t on ! controll] puts ! two motors 9 multiple1 ) "s resi/ance 9 ! circuit1 :i* resi/ance is cut out ^u ! foll[+ po9ts1 until at full spe$ ! two motors are 9 multiple1 )\t any resi/ance 9 ! circuit4 ,f\r ,motors4 ,:]e f\r motors are us$ on a c>1 z is frequ5tly ! case ) d\ble-truck c>s1 ! motors on ea* truck are usually controll$ j z 9 case ( ! two-motor equipm5t t has be5 describ$2 b ea* pair ( motors is op]at$ 9 multiple4 ,t is1 on ! fir/ po9ts ( ! controll]1 ! two motors ( a pair are 9 s]ies1 z 9 ,fig4 #ai1 & ! two pairs are 9 p>allel2 & on ! la/ po9ts ( ! controll]1 all ! motors are 9 p>allel1 z 9 ,fig4 #bj4 ,illu/ration3 ,fig4 #ai4 ,motor 9 ,s]ies4 ,illu/ration3 ,fig4 #bj4 ,motor 9 ,p>allel4 ,controll] ,con/ruction4 ,! controll] 7,type ,k7 %[n op5 9 ,fig4 #ba1 :i* 9 its v>i\s =ms is ! type mo/ commonly us$ on /reet c>s 9 ! ,unit$ ,/ates1 has a contact cyl9d] or drum m\nt$ ^u ! ma9 %aft ( ! controll]4 ,?is contact drum c>ries contact r+s insulat$ f ! drum1 & is suitably int]connect$1 z indicat$ 9 ,fig4 #bb1 :i* %[s ! contact r+s ( ! controll] z !y w\ld appe> if roll$ out flat4 ,contact f+]s are plac$ along ! left side ( ! controll]1 z se5 9 ,fig4 #ba1 "o = ea* r+ on ! drum2 & z ! controll] h&le is turn$ to revolve ?is drum1 ! contact f+]s make contact ) ! r+s on ! drum & give ! v>i\s connections4 ,alongside ! ma9 controll] drum is a rev]se drum :i* simply rev]ses ! armature connections ( ! two motors4 ,controll] ,wir+4 ,! connection betwe5 motors1 controll]s1 & resi/ances1 ) two motors & a ,k#f controll] is %[n 9 ,fig4 #bb4 ,a c>eful /udy ( ?is w %[ ! comb9ations to be ! same z indicat$ 9 ! diagram1 ,fig4 #ah4 ,! wir+ is r complicat$2 & 9 practice1 to avoid confusion1 ! ends ( ea* wire are label$ ) tags %[+ ! t]m9als to :i* !y belong4 ,illu/ration3 ,fig4 #ba4 ,controll]4 ,illu/ration3 ,c> ,wir+ = ,k-#f ,controll]s ) two ,motors ,fig4 #bb ,illu/ration3 ,fig4 #bc4 ,motors 9 ,s]ies4 ,illu/ration3 ,fig4 #bd4 ,motors 9 ,p>allel4 ,) ! aid ( ,figs4 #bb1 #bc & #bd1 ! wir+ ( a type ,k#f controll] ) two motors may be foll[$4 ,figs4 #bc & #bd are = a diff]5t controll] b c be us$ to assi/ 9 an und]/&+ ( ! complicat$ diagram #bb4 ,! curr5t leaves ! *oke or kick+ coil ( ! lightn+ arre/] & passes ?r\gh ! bl[ out coil ( ! controll]4 ,x !n goes to ! top f+] ,t ( ! controll]4 ,on ! fir/ po9t ! circuit is z %[n 9 ,fig4 #bc4 ,! top segm5t ,a makes contact ) ! top or trolley f+]4 ,all b ! l[] five segm5ts ( ! cyl9d] are electrically connect$ toge!r by means ( ! iron cyl9d] ^u :i* !y are m\nt$4 ,on ! fir/ po9t !n ! curr5t passes f ! cyl9d] ov] ,r1 & ) /raight s]ies connections ( ! resi/ances1 x goes ?r\gh all ( ! rheo/ats "u ! c>1 & returns to ! controll] ov] ! la/ resi/ance lead1 ,r4 ,beh9d ! motor cut-out swit*es at ! base ( ! controll] ?is lead is tapp$ into a wire "o end ( :i* leads to f+] #ai ( ! controll]1 & ! o!r end ?r\gh ! cut-out swit* & rev]se cyl9d] to ,no4 #a armature4 ,! curr5t takes ! latt] pa?1 passes ?r\gh ! armature ( ! motor & returns by way ( ! rev]se cyl9d]1 !nce ?r\gh ! fields ( ,no4 #a motor & !n ?r\gh ! cut-out swit* ( ,no4 #a motor & to f+] ,e1 ( ! controll]4 ,segm5ts ,o1 ,m1 ,n & ,l1 %[n 9 ,fig4 #bc1 & correspond+ segm5ts ( ,figs4 #bb & #bd1 are insulat$ f ! rema9d] ( ! controll] cyl9d]4 ,f f+] ,e & segm5t ,o 7,fig4 #bc7 ! curr5t passes ov] f+] #ae ?r\gh ,no4 #b cut-out swit* & ! rev]se cyl9d] to ! armature ( ,no4 #b motor4 ,return+ x passes ?r\gh ! rev]se cyl9d]1 !n back ?r\gh ! fields ( ,no4 #b motor & to ! gr\nd1 :i* is usually ?r\gh a connection on ! motor cas+4 ,on po9ts #b1 #c1 #d & #e1 ! successive s]ies po9ts ( ! controll] ,r1 ,r1 etc41 make contact ) segm5ts ,b1 ,c1 etc41 ,figs4 #bc & #bd1 until f9ally f+] #ai re/s on segm5ts ,j1 ! resi/ance is all cut out & ! motors are connect$ 9 s]ies directly across ! l9e4 ,a fur!r movem5t ( ! controll] h&le *anges ! motors f s]ies to multiple connection & ins]ts 9 ! circuit a portion ( ! ext]nal resi/ance4 ,!re are f\r sep>ate /ages 9 mak+ ?is *ange4 ,fir/1 ! resi/ance f+]s slide (f _! segm5ts & ! resi/ance is ins]t$ 9 ! l9e4 ,second1 f+]s ,e & ,g make contact ) segm5ts ,p & ,q4 ,motor ,no4 #a is !n across ! l9e 9 s]ies ) ! resi/ance2 ! circuit be+ f ,e to gr\nd ov] ,g4 ,:5 ! l[] f+] ,e makes contact ) ,p1 ! upp] "o has n yet left segm5t ,o4 ,?is %ort-circuits ,no4 #b motor1 ! pa? be+ f ! gr\nd1 up wire ,g1 !nce by way ( segm5ts ,p & ,q & ?r\gh connect+ clip ,v1 betwe5 ! two ,e f+]s back ?r\gh f+] #ae to ! motor4 ,a fur!r movem5t ( ! controll] h&le causes ! f+]s to leave segm5ts ,m & ,o & ,no4 #b motor is op5-circuit$ until f+] #ae makes contact ) segm5t ,n4 ,:5 ?is takes place ! motors are 9 multiple4 ,on ! successive po9ts aft] ?is ! ext]nal resi/ance is cut out 9 ! same mann] z previ\sly describ$4 ,by ref]5ce to ,fig4 #bb1 x w be notic$ t ! leads to ! motors & ! resi/ances are tapp$ on wires ( ! cables connect+ ! two controll]s on ! ends ( ! c>4 ,! two ends ( ^! wires1 ) ! exception ( ! armature wires1 lead to simil> b9d+ po/s on ! two controll]s4 ,! armature wires are int]*ang$ connect+ at "o controll] into b9d+ po/ ,a ,a1 :ile ! o!r end connects into b9d+ po/ ,a4 ,?is *ange ( connection is necess>y 9 ord] t ! rev]se h&les be =w>d = =w>d direction ( movem5t ( ! c>4 ,illu/ration3 ,fig4 #be4 ,=w>d ,position ( ,rev]se4 ,to rev]se a s]ies motor x is simply necess>y to rev]se ! direction ( fl[ ( ! curr5t 9 ei!r ! armature or field4 ,= sev]al reasons1 x is advantage\s 9 ! case ( ! /reet railway motor to rev]se ! curr5t 9 ! armature r ?an 9 ! field4 ,figs4 #be & #bf %[ h[ ?is is accompli%$4 ,! squ>es %[n 9 ! figures repres5t ! lugs on ! rev]se cyl9d] z %[n 9 ,fig4 #ba4 ,) ! rev]se h&le 9 "o position 7,fig4 #be71 ! l>ge lugs are "u ! rev]se f+]s1 & curr5t passes f f+] #ai to f+] ,a1 & f f+] #ae to f+] ,a4 ,fig4 #bf %[s ! relative position ( rev]se f+]s & lugs = ! rev]se position ( ! controll] h&le4 ,9 ?is case ! curr5t passes f f+] #ai to ,a ,a1 & f f+] #ae to f+] ,a ,a4 ,! effect is to *ange ! direction ( fl[ 9 ! armatures :ile t 9 ! fields rema9s ! same z may be obs]v$ by ! arr[s4 ,illu/ration3 ,fig4 #bf4 ,rev]se ,position ( ,rev]se4 ,wir+ ( ,type ,l ,controll]s4 ,! type ,l controll]1 %[n 9 ,fig4 #bg1 :ile accompli%+ ! same results z ! type ,k1 is wir$ 9 a radically diff]5t mann]4 ,! circuit is op5$ 9 *ang+ f s]ies to multiple connections4 ,! controll] h&le makes two complete revolutions 9 mov+ f ! s]ies to ! multiple position4 ,x is ge>$ to ! rheo/atic cyl9d] 9 su* a mann] t ! fir/ half ( bo? ! fir/ & second revolutions gives ?is cyl9d] "o complete turn4 ,dur+ ! second half ( ! revolution ! cyl9d] is return$ to its orig9al position4 ,! controll] h&le is s connect$ to ! commutat+ arm t ?is /&s 9 a c5tral position = ! (f position ( ! h&le4 ,at ! beg9n+ ( ! fir/ revolution x is swung to ! left1 ?r[+ ! motors 9 s]ies4 ,at ! beg9n+ ( ! second revolution x is mov$ to ! "r1 putt+ ! motors 9 multiple4 ,! rheo/ats in/ead ( be+ wir$ 9 s]ies are connect$ 9 multiple4 ,curr5t passes f ! bl[-out coil to ! bottom f+]s ( ! controll] ,s1 & !nce to ! rheo/ats4 ,on ! fir/ po9t ! curr5t returns ov] ,r to ! controll] cyl9d]4 ,x passes (f ?r\gh a coll> at ! base ( ! cyl9d] ?r\gh ,no4 #a cut-out1 & ! rev]se1 :i* is %[n 9 ! c5tral position1 to ,no4 #a motor4 ,on return+ to ! controll] ov] ,e x passes to ! upp] section ( ! commutat+ arm4 ,9 ! diagram ?is is %[n 9 ! c5tral position4 ,9 s]ies x is ?r[n to ! left4 ,! curr5t !n passes f ! commutat+ arm to ,no4 #b cut-out1 & to ,no4 #b motor4 ,movem5t ( ! controll] h&le fur!r multiplies ! pa?s ?r\gh ! rheo/ats & f9ally1 :5 f+]s ,s re/ on ! cyl9d]1 ! rheo/ats are %ort-circuit$4 ,if ! controll] h&le is mov$ /ill f>!r1 ! rheo/at cyl9d] is return$ to ! (f position & ! commutat+ arm is ?r[n to ! left4 ,) ! arm 9 ?is position ! curr5t divides1 "o portion pass+ to ,no4 #a motor z be=e & to gr\nd by way ( ! upp] section ( ! commutat+ arm2 :ile ! o!r bran* goes by way ( ! l[] section ( ! commutat+ arm to ! cut-out swit* = ,no4 #b motor & !nce to ! motor4 ,illu/ration3 ,diagram ( ,connections = ,l#b ,controll] ,fig4 #bg4 ,rev]s+ is accompli%$ by "o-qu>t] revolutions to ! "r & left ( ! segm5ts %[n4 ,x is evid5t t ?is w connect ei!r ,a or ,a ,a1 to ! trolley4 ,& likewise connect ! o!r armature leads4 ,rev]sal4 ,! rev]s+ h&le & ! ma9 controll] h&le are made int]lock+ s t ! motors _c be rev]s$ )\t fir/ ?r[+ ! controll] to (f position4 ,?is is to prev5t damage to ! motors ?r\gh c>eless or inadv]t5t ?r[+ ( ! rev]se h&le :5 ! controll] is on "s ( its high] po9ts4 ,su* a rev]sal w\ld cause an enorm\s curr5t to fl[ ?r\gh ! motors1 & w\ld be likely to damage !m & to op5 all ! circuit break]s & fuses 9 t circuit4 ,! reason = ! enorm\s fl[ ( curr5t is1 ( c\rse1 t ! c\nt]-electromotive =ce ( ! motors1 :5 rev]s$ ) ! c> go+ at "s spe$1 w\ld mat]ially add to ! electromotive =ce ( ! trolley l9e1 in/ead ( oppos+ x z :5 ! c>s are 9 op]ation4 ,! curr5t fl[+ ?r\gh ! motor circuit w\ld !n be equal to 7electromotive =ce ( l9e electromotive =ce ( motors7 7resi/ance ( motors71 :i* w\ld result 9 a v l>ge curr5t4 ,magnetic ,bl[-,out4 ,on ! ,type ,k controll] z well z on mo/ o!r successful controll]s1 ! fla%+ or arc+ betwe5 contact r+s & f+]s1 :i* occurs :5 ! circuit is brok51 is mat]ially r$uc$ by a magnet t produces :at is call$ ! magnetic bl[-out to ext+ui% ! arc4 ,?is magnet d]ives its curr5t f ! ma9 circuit1 & is s arrang$ z to create a /rong magnetic field 9 ! neighborhood ( ! place :]e ! arc is =m$4 ,fig4 #ba %[s a ,type ,k controll] op5 ) ! magnetic bl[-out magnet ?r[n back on a h+e4 ,! coil :i* produces ?is magnet is se5 9 ! "r side ( ! controll]4 ,! ma9 contact drum is 9 ! middle1 & ! rev]s+ drum at ! "r h&4 ,!re are 9 use a numb] ( o!r controll]s built ^u ^! same g5]al pr9ciples b diff]+ 9 me*anical arrangem5t4 ,controll] ,not*es4 ,all controll]s are provid$ ) "s device :i* prev5ts ! motorman f /opp+ ! controll] h&le betwe5 ! v>i\s po9ts or not*es1 z ! /opp+ betwe5 po9ts might result 9 draw+ an arc or an imp]fect contact4 ,! mo/ common arrangem5t to prev5t ?is is a not*$ :eel on ! controll] %aft1 aga9/ :i* be>s a small :eel ( j ! "r size to ent] ! not*es4 ,! small :eel is held aga9/ ! not*$ :eel by a /rong spr+4 ,z ! t5d5cy ( ! small :eel is to seek ! bottom ( ! not*es1 x is difficult to /op ! controll] h&le any:]e betwe5 not*es1 & ! motorman is ?us giv5 a guide :i* tells him )\t any ef=t on 8 "p j :]e ! not*es are4 ,to prev5t advanc+ ! controll] h&le too rapidly & avoid ! j]k+ ( pass5g]s1 excessive curr5ts & slipp+ ( :eels dur+ accel]ation1 sev]al devices h be5 plann$4 ,on ! multiple unit control sy/ems1 a limit swit* is usually provid$ :i* prev5ts ! controll] advanc+ :5 ! curr5t exce$s a pr$et]m9$ am\nt4 ,a device to accompli% ! same results on ! ,k type ( controll]s is t]m$ ! ,automotone]4 ,a cam connect$ ) a da% pot prev5ts movem5t ( ! controll] h&le to ! successive not*es fa/] ?an a previ\sly prescrib$ rate4 ,a swit* is usually provid$ 9 a controll]1 = cutt+ out ( s]vice "o motor or a pair ( motors if defective1 & all[+ ! c> to proce$ ) ! good motor or motors4 ,illu/ration3 ,fig4 #bh;a4 ,c> ,wir+ = ,g4 ,e4 ,tra9 ,control ,sy/em4 ,illu/ration3 ,,we/+h\se #cjj ,k4,w4 ,,direct ,,curr5t ,,eng9e ,,type ,,?ree-,,wire ,,g5]ators4 ,pittsburgh1 ,c9c9nati1 ,*icago & ,/4 ,l\is ,railroad1 ,columbus1 ,ohio4 ,,multiple-,,unit ,,control4 ,a sy/em call$ 8multiple-unit control0 or 8tra9 control0 has come into use :]e x is desir$ to op]ate motors "u a numb] ( diff]5t c>s 9 a tra92 all ! motors be+ controll$ f ! head ( ! tra9 or f any o!r po9t on ! tra9 :]e ! motorman may be /ation$4 ,!re are sev]al types ( multiple-unit control4 ,9 all ( !m !re is on ea* c> a controll] ( "s k9d :i* controls ! curr5t fl[+ to ! motors on t c>4 ,?is controll] is op]at$ f a di/ance by means ( electro-magnetic or electro-pneumatic devices controll$ by circuits call$ pilot circuits1 :i* circuits are connect$ to ! motorman's controll]4 ,all ! pilot circuits ( a tra9 are connect$ toge!r by means ( tra9 plugs :i* make ! connections betwe5 ! c>s4 ,! pilot circuits ( ea* c> are connect$ to a motorman's controll] on t c> & ?is makes x possible to op]ate ! tra9 f any controll]4 ,sprague ,multiple-,unit ,sy/em4 ,9 ! e>lie/ =m ( multiple-unit control--:i* 0 t devis$ by ,f4 ,j4 ,sprague--! motors on ea* c> 7 controll$ by an ord9>y ,type ,k controll]1 :i* _h ge>$ to its %aft a small pilot motor4 ,! pilot motor 0 controll$ by ! pilot circuits connect$ ) ! motorman's controll]4 ,9 ! m rec5t =ms ( multiple-unit control1 ! use ( ma9 controll]s hav+ contact cyl9d]s has be5 practically ab&on$4 ,! contacts are made in/ead by a numb] ( electro-magnetic or electro-pneumatic contact devices sometimes call$ contactors4 ,g5]al ,electric ,tra9 ,control4 ,9 ! ,g5]al ,electric tra9-control sy/em ea* contact = ! motor circuits is made by a sol5oid magnet :i* draws toge!r two heavy copp] contact f+]s to e/abli% ! circuit4 ,a magnetic bl[-out coil 9 s]ies ) ! contact is also provid$4 ,! contactors make contact only :5 en]giz$ by a small am\nt ( curr5t f ! ma/] or motorman's controll]4 ,9 ,fig4 #bh;a is a diagram ( ! c> wir+ = a motor c> equipp$ ) ?is sy/em4 ,! motorman's controll] is a drum controll]1 b is comp>atively small s9ce x has to h&le only ! small am\nt ( curr5t necess>y to op]ate ! sol5oid magnets ( ! contactors4 ,x is evid5t t by connect+ toge!r ! pilot circuits1 :i* are connect$ to ! motorman's controll]1 s t ! pilot circuits w be cont9u\s = ! entire l5g? ( ! tra91 any numb] ( c>s equipp$ ) ! tra9-control sy/em c be op]at$2 & simil> contacts w be made by ! contactors "u all ! c>s simultane\sly1 by virtue ( ! circuits e/abli%$ by ! ma/] controll] at any plat=m4 ,besides controll+ ! contactors1 ! ma/] or motorman's controll] mu/ control an electro-magnetic rev]s+ swit*1 or rev]s]1 to *ange ! direction ( c> travel4 ,! h&le ( ! motorman's controll] is provid$ ) a pu% button1 :i* mu/ be depress$ :ile ! curr5t is turn$ on4 ,%\ld ! motorman release ?is pu%1 ! circuit ?r\gh ! controll] w be op5$ & all ! contactors w fall op54 ,?is h&le is call$ ! dead man's h&le because x is put !re to provide = cutt+ (f ! curr5t %\ld ! motorman fall dead or 9 a fa9t at 8 po/4 ,! fl[ ( ! curr5t 9 ! control circuits1 :i* op]ates ! rev]s] & picks up ! contactors on ! sev]al po9ts may be foll[$ 9 ! diagram ,fig4 #bh;a4 ,) ! rev]se h&le 9 ! =w>d position & ! controll] on ! fir/ po9t1 curr5t passes f ! ma9 circuit ?r\gh a s+le-pole fus$ swit* call$ ! control swit* & ?r\gh ! auxili>y bl[-out coil to a f+] be>+ on ! upp] section ( ! ma/] controll] cyl9d] by :i* connection is e/abli%$ to ! adjac5t f+] & !nce to ! rev]se cyl9d]4 ,x leaves ?is ov] wire ,no4 #h1 pass+ by way ( ! connection bo>d & control cut-out swit* to ! =w>d op]at+ coil ( ! rev]s]1 !nce ?r\gh ! =w>d bl[-out coil & ov] wire #ha1 ?r\gh ! swit* und]nea? contactor ,no4 #b & to gr\nd ,g1 by way ( wire ,b #b aft] pass+ ?r\gh ! fuse %[n4 ,! curr5t ?r\gh ! op]at+ coil ( ! rev]s]1 hav+ ?r[n ?is1 ! pa? is *ang$ some:at4 ,! curr5t !n in/ead ( pass+ f ! rev]s] ov] wire #ha1 is conduct$ ?r\gh wire #ae1 ?r\gh ! op]at+ coils ( contactors ,no4 #a1 #b1 #c1 & #aa 9 s]ies1 ?r\gh ! swit* "u contactor ,no4 #ab1 & to gr\nd ?r\gh f+] #a ( ! controll]4 ,contactors #a & #b are 9 multiple & :5 rais$ connect ! trolley ) ! contactors controll+ ! resi/ance leads4 ,contactor #c connects ,r to ! l9e :ile contactor #aa places ! two motors 9 s]ies4 ,! motors !n op]ate ) all ( ! resi/ance 9 circuit4 ,:5 contactor #b raises1 x op5s ! swit* imm$iately bel[ x1 mak+ x impossible = ! rev]se to op]ate :ile curr5t is fl[+ ?r\gh ! motors4 ,on ! second not* ( ! controll] an additional pa? is op5$ by way ( f+] #c ( ! controll]4 ,?is pa? leads f f+] #c ?r\gh f\r ( ! control circuit rheo/at coils1 ?r\gh contactor ,no4 #e & to gr\nd ov] #cb4 ,on ! #crd1 #d? & #e? po9ts contactors #f1 #g & #i respectively are rais$4 ,! motors are !n 9 full s]ies4 ,betwe5 ! #e? & #f? po9ts all ! control circuits are brok5 prep>atory to />t+ ! multiple connections ( motors4 ,on ! #f? or ! fir/ multiple po9t ! gr\nd ?r\gh f+] #a ( ! ma/] controll] is op5$ :ile a gr\nd ?r\gh f+] #c is e/abli%$4 ,! curr5t f ! rev]s] !n1 aft] rais+ contactors #a & #b z be=e1 in/ead ( pass+ ?r\gh contactors #c & #aa1 passes ?r\gh ! coils ( #d1 #ab & #ac1 ?r\gh ! swit* "u contactor #aa & to gr\nd ov] f+] #b4 ,contactor #ab connects motor ,no4 #b to ,r1 :ile contactor #ac gr\nds ,no4 #a motor4 ,! motors n[ op]ate 9 p>allel & on successive not*es ( ! controll]1 contactors #f1 #g1 #h1 & #i are rais$1 cutt+ out all ( ! resi/ance4 ,! swit*es und]nea? contactors #aa & #ab make x impossible = #aa to raise ) #ab & #ac or vice v]sa4 ,! reason = ?is arrangem5t is v evid5t1 z a direct gr\nd = ,r w\ld result4 ,! ,we/+h\se ,electro-,pneumatic ,sy/em ( ,control4 ,9 ?is sy/em ( multiple unit or tra9 control1 ! curr5t to ! motors is suppli$ ?r\gh a set ( unit swit*es or circuit break]s :i* are sometimes plac$ 9 a circul> case or turret und]nea? ! c> & 9 o!r cases are rang$ 9 a r[ "u ! c>4 ,! op5+ & clos+ ( ^! unit swit*es is done ) compress$ air act+ on a pi/on 9 an air cyl9d]4 ,:5 ! circuit is to be clos$1 compress$ air is admitt$ beh9d ! pi/on & =ces x d[n aga9/ ! t5sion ( a sev5ty-p\nd spr+1 & ! contacts are br\ght toge!r4 ,:5 ! swit* is to be op5$1 ! air is let out ( ! cyl9d] & ! spr+ =ces ! pi/on back4 ,! air supply is obta9$ f ! /orage tanks ( ! air brake sy/em4 ,! valve controll+ ! air supply to ! cyl9d] ( ea* unit swit* is op]at$ by electromagnets :i* d]ive curr5t f a sev5 cell1 f\rte5-volt1 /orage batt]y4 ,! small ma/] controll] op]at$ by ! motorman1 makes & breaks ! batt]y connections to ! magnets controll+ ! air valves4 ,illu/ration3 ,fig4 #bh;b4 ,c> ,wir+ = ,we/+h\se ,control ,sy/em4 ,an advantage ( ?is ov] o!r multiple-unit sy/ems is t by ! use ( batt]y curr5t ! control sy/em is n di/urb$ by int]ruptions ( ! ma9 supply ( curr5t4 ,! *ief advantage ( ?is is t x makes x possible to rev]se ! motors & op]ate !m z brakes 9 em]g5cies at all times4 ,! batt]y is *>g$ f ! ma9 l9e ?r\gh lamps z resi/ance1 or may be *>g$ by be+ connect$ 9 s]ies ) ! air compressor motor4 ,9 ! accompany+ diagram1 ,fig4 #bh;b1 !re are two batt]ies %[n :i* are *>g$ 9 s]ies ) ! compressor motor4 ,by means ( two d\ble-pole1 d\ble-?r[ swit*es1 fir/ "o & !n ! o!r batt]y is connect$ = *>g+ & = s]vice4 ,! batt]y is *>g$ 9 %unt ) a resi/ance & a relay is connect$ 9 ! circuit z %[n1 s z to op5 ! batt]y circuit :5ev] ! curr5t ?r\gh ! motor /ops1 & ?us prev5t ! batt]y dis*>g+ ?r\gh ! resi/ance4 ,! ma/] controll] has a d\ble set ( segm5ts 9 ord] to decrease ! l5g? ( ! %aft4 ,! h&le1 !re=e1 is mov$ only "o-six? ( a revolution f (f to full spe$4 ,! v>i\s circuits c be trac$ by ! lett]s & numb]s ea* wire be>s1 s t ! circuits w n be gone ov] 9 detail4 ,! fir/ position ( ! ma/] controll] ?r[s ! rev]s] swit* 9 ! prop] direction & also closes ! ma9 circuit break]4 ,on ! second po9t ! motors are connect$ 9 s]ies ) all resi/ance 9 circuit1 & ^! resi/ances are automatically cut out "o by "o4 ,on ! next po9t ( ! controll] ! motors are 9 multiple & ! resi/ances are automatically cut out 9 a simil> mann]4 ,! automatic cutt+ out ( resi/ances is accompli%$ by a limit swit* 9 conjunction ) op]at+ & hold+ coils on ! electro-pneumatic valves4 ,?is limit swit* is a k9d ( a relay :i* has ! curr5t f "o ( ! motors fl[+ ?r\gh its coil & :i* acts to op5 a c]ta9 batt]y circuit :i* op]ates ! electro-pneumatic valves :5ev] ! curr5t 9 ! motor circuit 9 "q exce$s ! am\nt = :i* ! limit swit* is set4 ,! automatic accel]ation or cutt+ out ( resi/ance is accompli%$ z foll[s3 ,ea* electro-pneumatic valve has two magnet coils1 "o ( :i* is an op]at+ coil & ! o!r a hold+ coil = hold+ ! valve op5 aft] x is op]at$4 ,:5 fir/ ! curr5t fl[s ?r\gh a circuit to "o ( ! electro-pneumatic valves1 x fl[s ?r\gh ! op]at+ coil & op]ates ! valve to close ! correspond+ swit* or swit*es ( ! ma9 circuit by turn+ ! air into ! cyl9d]s4 ,z soon z ! ma9 swit* is clos$1 x cuts into circuit ! hold+ coil ( its correspond+ electro-pneumatic valve & ?is coil w1 ) ! batt]y curr5t1 hold ! swit* clos$ ev5 ?\gh ! circuit to ! op]at+ coil may be op5$ mom5t>ily by ! limit swit* z ea* /ep ( resi/ance is cut out4 ,?is prev5ts ! swit*es f op5+ :5 !y are once clos$ & all[s ! op]at+ coils to op5 an air valve ea* "t ! curr5t ?r\gh ! limit swit* coil falls bel[ ! am\nt = :i* x is set4 ,! contacts :i* close ! hold+ coil circuit on ea* valve :5ev] a ma9 swit* is clos$1 are call$ int]locks & are indicat$ on ! diagram4 ,illu/ration3 ,fig4 #bi4 ,diagram ( ,electric ,heat]s4 ,! ma9 l9e circuit break]1 :i* is electro-pneumatically op]at$1 w op5 automatically on ov]load & c be reset by ! motorman on all ! c>s ( a tra9 by clos+ a swit* locat$ beside ea* controll]4 ,,c> ,,heat]s4 ,electric ,heat]s = w>m+ c>s 9 w9t]1 consi/ ( iron wire coils :i* are w>m$ by ! passage ( electric curr5t ?r\gh !m4 ,! heat s evolv$ v>ies z ! resi/ance multipli$ by ! squ>e ( ! curr5t4 ,! iron wire coils ( ! heat] are m\nt$ on non-combu/ible insulat+ supports1 & are arrang$ s t !re is a free circulation ( air ?r\gh !m4 ,! coils are surr\nd$ ) a p]=at$ metal case1 ! object ( :i* is to prev5t injury to ! coils & to prev5t p]sons or clo?+ com+ 9 contact ) ! hot1 live wires ( ! coils4 ,heat]s are sometimes arrang$ s t !y c be connect$ 9 s]ies or p>allel to give diff]5t degrees ( heat4 ,! diagram1 ,fig4 #bi1 %[s ! mo/ common arrangem5t ( electric heat]s rec5tly4 ,! tap f ! trolley %\ld be tak5 (f on ! trolley side ( ! circuit break]4 ,aft] pass+ ?r\gh a fuse ! circuit goes to ! swit*4 ,ea* ( ! heat]s conta9s two coils1 "o ( high] resi/ance ?an ! o!r4 ,two indep5d5t circuits are run f ! swit*1 ?r\gh ! heat]s & to ! gr\nd4 ,"o circuit passes ?r\gh ! high resi/ance coils ( ! sev]al heat]s :ile ! o!r goes ?r\gh ! l[ resi/ance coils4 ,! swit* has ?ree po9ts4 ,on ! fir/ po9t a circuit is made ?r\gh ! high resi/ance coils4 ,! second po9t connects ! l[ resi/ance coils :ile ! ?ird po9t puts bo? circuits 9 s]vice4 ,) ?is arrangem5t ?ree gradations ( heat may be obta9$4 ,to avoid complicat$ wir+ sometimes b "o circuit is employ$4 ,9 su* a case ! heat mu/ ei!r be all on or (f1 no gradations be+ possible4 ,! *ief difficulty enc\nt]$ ) electric heat]s is ! break+ ( ! wires because ( ! scale ( oxide t =ms gradually :5 !y are run at a high temp]ature or because ( wat] /rik+ !m f pass5g]s' clo?+ on wet days1 :i* causes ! wires to snap4 ,! ,consolidat$ ,c> ,heat+ ,company gives ! foll[+ data on ! curr5t requir$ to heat c>s3 ,l5g? ( ,c> ,amp]es4 ,body4 ----------------- ,swit* ,positions4 ----------------- #a #b #c ---------------------------------------- -------------- #ad to #bj feet #c #d #g ,av]age conditions #bj to #bh 0 #c #f #i #bh to #cd 0 #d #g #aa ,sev]e/ conditions #ah to #bd feet #d #g #aa #bh to #cd 0 #f #h #ad ---------------------------------------- -------------- ,9 8 ,electrical ,eng9e]s' ,h& ,book1 ,mr4 ,fo/] gives results ( te/s made on ,brooklyn c>s z foll[s3 ,c>s4 ,temp]ature ,f4 ,consumption4 ---------------------------------------- ------------------- ,doors4 ,w9d[s4,cont5ts,outside4,av]age,watts4 ,amp]es cu4 ft4 9 c>4 at #ejj volts4 ---------------------------------------- ----------------- #b #ab #hej #bh #ee #bbie #d4f #b #ab #hej #g #ci #bcbe #d4f #b #ab #hjh #bh #di #bahj #d4c #b #ab #iac #ce #eb #bgde #d4e #d #af #ajab #g #df #cjch #f4 #d #af #ajab #bh #ed #cafj #f4c ---------------------------------------- ----------------- ,:5 n wat*$ c>efully consid]able curr5t may be wa/$ by all[+ ! heat]s to rema9 turn$ on :5 n ne$$4 ,_m companies hang out signs :]e motorm5 may obs]ve !m1 indicat+ :5 ! heat]s %all be turn$ on & to :at po9t4 ,illu/ration3 ,fig4 #cj4 ,electric ,heat]4 ,! be/ practice 9 electric heat+ is to h pl5ty ( heat]s & run ! wire at a l[ temp]ature1 r ?an attempt to heat ) a few at high temp]ature4 ,! great] ! numb] ( heat]s ! l>g] ! radiat+ surface ar\nd :i* ! air c circulate & a giv5 am\nt ( c> heat+ c be accompli%$ ) less curr5t ?an ) a few high temp]ature heat]s4 ,! depreciation ( ! heat] wires is less ! l[] ! temp]ature at :i* !y are op]at$4 ,an electric heat] is %[n 9 ,fig4 #cj4 ,hot-,wat] ,heat]s are frequ5tly us$ on l>ge electric c>s4 ,hot-wat] pipes are plac$ along ! sides ( ! c>1 & connect$ ) a /ove conta9+ hot-wat] coils at "o end ( ! c>4 ,! wat]1 z x is heat$ 9 ! /ove or heat]1 exp&s1 & consequ5tly becomes light] p] cubic in* or o!r unit ( volume2 x !re=e t5ds to rise :5 balanc$ aga9/ ! cold] wat] 9 ! c> pipes4 ,hot wat] leaves ! top ( ! heat]1 fl[s up to an expansion tank & !n d[n ?r\gh ! c> pip+1 & back to ! bottom ( ! heat]4 ,! c> pip+ slopes cont9u\sly d[n f ! top connection to ! bottom connection ( ! heat]4 ,at ! top1 an op5+ to ! atmosph]e is provid$ ?r\gh a small wat] tank1 call$ an expansion tank4 ,?is prev5ts wat] pressure bur/+ ! pipes z !y become heat$1 & all[s any /eam t may h =m$ to escape4 ,! mo/ mod]n hot-wat] heat]s = c>s are completely clos$ except z to ! a% pit at ! bottom & a small fe$ door 9 ! top4 ,! latt] is lock$ s t ! fire _c come out ev5 if ! c> is tipp$ ov] 9 a wreck4 ,fig4 #ca %[s ! pipes ( a hot-wat] heat+ in/allation4 ,illu/ration3 ,fig4 #ca4 ,pipes = ,hot-,wat] ,heat+4 ,,c> ,,wir+4 ,! wires f motors to controll]s1 :5 plac$ 9 expos$ position "u ! c>1 are bun*$ 9 cables or cov]$ ) hose4 ,9 "s cases special runways are provid$ 9 ! bottom ( ! c> to accommodate ! c> wir+4 ,all ! wir+ 9 a c> %\ld be heavily insulat$ ) moi/ure-pro( rubb]-cov]$ wire1 & fur!r protect$ f me*anical abrasion by a t\gh out] cov]+4 ,/r&$ rubb] insulat$ wire is us$ almo/ exclusively = wir+ all p>ts ( ! c>4 ,a g5]al idea ( ! pa? ( ! motor circuit wir+ may be obta9$ by ref]5ce to ,fig4 #bb4 ,! ma9 lead aft] leav+ ! trolley /& is cleat$ to ! trolley bo>d on top ( ! c>4 ,at ! end ( ! c> x passes ?r\gh ! ro( & to ! circuit break]4 ,on leav+ ! break] x is l$ d[n a po/1 ?r\gh ! floor & to ! *oke coil & lightn+ arre/] und]nea? ! c>4 ,x !n passes to ! trolley t]m9al ( ! controll]4 ,! tap = ! light wir+ 7al?\gh %[n o!rwise 9 ! draw+7 is usually tak5 (f ! ma9 circuit be=e ! circuit break] is rea*$4 ,?is arrangem5t all[s ! lamps to be burn$ :5 ! circuit break] is op54 ,aft] pass+ ?r\gh fuses & swit*es 9 ! motorman's cab ! circuit = ! lights is l$ ?r\gh ! c> 9 m\ld+ conceal+ x4 ,! wires runn+ betwe5 ! motors1 controll]s & resi/ance frames und]nea? ! c>1 z has be5 /at$1 are (t5 c>ri$ 9 canvas hose4 ,usually two cables are made up1 = %\ld all ! wires necess>y be plac$ 9 "o cable ?is w\ld become too bulky to be prop]ly cleat$ up4 ,to make ! canvas hose wat]pro( & to prolong its life x is usually giv5 sev]al coats ( asphaltum pa9t4 ,! wir+ ( ! new c>s ( ! ,new ,york subway is an example ( ! mo/ advanc$ practice4 ,all ! wires "u ! c>s are c>ri$ 9 8loricat$0 conduit1 :i* consi/s ( a wr\ght-iron tube heavily enamel$ bo? inside & out4 ,! motor leads & ! o!r l>g] wires are c>ri$ 9 sep>ate conduits4 ,! conduits are usually hung to ! /eel beams ( ! floor fram+ by /rap bolts4 ,?is me?od ( wir+ gives a reasonable assurance t x w n become defective4 ,moreov]1 x less5s fire risk4 ,! conduits are all gr\nd$ & %\ld "o ( ! wires come 9 contact ) ! conduit c>ry+ x1 ! dead gr\nd result+ w\ld cause ! fuse to bl[ in/antly1 & all dang] w\ld cease4 ,,resi/ances4 ,! type ( resi/ance n[ mo/ common = heavy motor equipm5t is 9 ! =m ( ca/-iron grids1 :i* are assembl$ toge!r & connect$ 9 s]ies4 ,^! grids are suffici5tly /iff to r5d] unnecess>y any solid insulation betwe5 !m1 & h5ce !y c radiate heat to ! be/ advantage4 ,! only difficulty exp]i5c$ ) !m is f ! w>p+ or crack+4 ,resi/ances = light] equipm5t are compos$ ( %eet-/eel ribbons w\nd 9 coils4 ,ea* turn ( a coil is insulat$ f ! next by asbe/os4 ,o!r =ms ( %eet-/eel resi/ance ) asbe/os insulation betwe5 ! turns1 h also be5 us$4 ,9 ,fig4 #cb is %[n a ,we/+h\se grid type div]t] = /reet railway equipm5t4 ,,electric ,,c> ,,accessories4 ,canopy ,swit*4 ,an ov]head swit*1 sometimes call$ a 8canopy swit*10 is commonly plac$ ov] ea* /reet-c> plat=m :]e a controll] is locat$1 usually 9 ! deck or canopy above ! motorman's head4 ,?is is simply a s+le-po9t swit* t may be us$ by ! motorman to cut ! trolley curr5t (f f ! controll] wir+ s t ! controll]s w be absolutely dead4 ,:5 two su* swit*es are us$1 "o on ea* end ( ! c>1 !y are connect$ 9 s]ies4 ,illu/ration3 ,fig4 #cb4 ,grid ,type ( ,resi/ance4 ,c> ,circuit ,break]4 ,frequ5tly on l>ge equipm5ts an automatic circuit break] is provid$ in/ead ( ?is ov]head swit*4 ,?is circuit break] c be tripp$ by h& to op5 ! circuit :5ev] desir$2 & is also equipp$ ) a sol5oid magnet1 :i* c be adju/$ s t x w trip or op5 ! circuit break] at approximately :atev] curr5t x is set =4 ,?is circuit break] protects ! motor & c> wir+ f excessive curr5t1 su* z w\ld occur 9 case ( a %ort circuit 9 motors or c> wir+1 or 9 case ! motorman turn$ on curr5t s rapidly z to endang] ! w9d+s ( ! motors4 ,circuit break]s1 h[ev]1 are mo/ commonly us$ on c>s hav+ controll]s locat$ at only "o end 9 a motorman's cab4 ,wir+ ( ,circuit ,break]s & ,canopy ,swit*es4 ,figs4 #cc1 #cd1 & #ce %[ ! me?ods ( wir+ circuit break]s & canopy swit*es = d\ble-end c>s4 ,illu/ration3 ,fig4 #cc4 ,9 ! p>allel connection z %[n 9 ,fig4 #cc1 ! trolley leads aft] pass+ ?r\gh ! *oke coils g directly to ! bl[-out coil ( ! controll]s4 ,aside f ! fact t two lightn+ arre/]s & *oke coils are requir$1 ?is me?od is pref]able = automatic circuit break]s4 ,illu/ration3 ,fig4 #cd4 ,fig4 #cd %[s ! h&-op]at$ circuit break]s connect$ 9 s]ies4 ,?is me?od is us$ :]e non-automatic break]s are employ$1 b = automatic break]s x has ! objection t an ov]load w\ld ?r[ ! break] set at ! l[e/ po9t4 ,?is might be ! break] on ! opposite end to t occupi$ by ! motorman & 9 su* an ev5t w\ld necessitate a trip to ! o!r end to set ! break]4 ,fig4 #ce %[s a me?od ( p>allel connection requir+ b "o lightn+ arre/]4 ,?is me?od has ! objection t ! motorman on ! front end w\ld h no assurance t by ?r[+ ! break] ov] him ! p[] w\ld be cut (f4 ,! re> break] might h be5 c>elessly left set4 ,illu/ration3 ,fig4 #ce4 ,illu/ration3 ,fig4 #cf4 ,fuses4 ,a fuse is plac$ 9 s]ies ) ! motor circuit be=e x ent]s ! controll] wir+1 b :]e circuit break]s are us$ in/ead ( canopy swit*es1 ! fuse box may sometimes be disp5s$ )4 ,! fuse box on /reet c>s is usually locat$ und]nea? "o side ( ! c> body :]e x is accessible = replac+ fuses1 b :]e a motorman's cab is us$1 ! fuse may be plac$ 9 ! cab4 ,! fuse may be ( any ( ! types 9 common use1 ei!r op5 or enclos$4 ,9 ! ,we/+h\se fuse box x is necess>y only to op5 ! box & drop 9 a piece ( /raight copp] wire ( ! "r l5g? & size4 ,! clos+ ( ! box clamps ?is wire to ! t]m9als & e/abli%es a circuit ?r\gh ! copp] wire z a fuse4 ,( c\rse ?is copp] wire is ( small en\gh size to be fus$ by a dang]\sly heavy curr5t4 ,lightn+ ,arre/]s4 ,a lightn+ arre/] is us$ on all c>s tak+ curr5t f ov]head l9es4 ,! lightn+ arre/] is connect$ to ! ma9 circuit z x comes f ! trolley base1 be=e x rea*es any ( ! o!r electrical devices on ! c>1 s t x may af=d !m protection4 ,a common type ( lightn+ arre/] is %[n 9 ,fig4 #cf4 ,"o t]m9al ( ! lightn+ arre/] is connect$ to ! motor frame s z to gr\nd x1 & ! o!r is connect$ ) ! trolley4 ,9 mo/ =ms ( lightn+ arre/]1 a small air gap is provid$1 n su* z to p]mit ! #ejj-volt curr5t to jump across1 b across :i* ! lightn+ w jump on acc\nt ( its high pot5tial4 ,to prev5t an arc be+ e/abli%$ across ! air gap by ! p[] h\se curr5t aft] ! lightn+ dis*>ge has tak5 place & />t$ ! arc1 "s means ( ext+ui%+ ! arc is provid$4 ,9 ! ,g5]al ,electric ,company's lightn+ arre/]1 ! arc is ext+ui%$ by a magnetic bl[-out1 :i* is en]giz$ by ! curr5t t fl[s ?r\gh ! lightn+ arre/]4 ,! in/ant ! dis*>ge takes place ! curr5t fl[s across ! air gap4 ,! magnetic bl[-out ext+ui%es ! arc1 & ?is op5s ! circuit1 leav+ ! arre/] ready = ano!r dis*>ge4 ,9 ! ,g>ton-,daniels lightn+ arre/] a plung] contact op]at$ by a sol5oid op5s ! circuit z soon z curr5t beg9s to fl[ ?r\gh ! arre/]4 ,?is plung] op]ates 9 a magnetic field1 :i* ext+ui%es ! arc4 ,a *oke coil1 consi/+ ( a few turns ( wire ar\nd a wood5 drum1 is plac$ 9 ! circuit lead+ to ! motors at a po9t j aft] x has pass$ ! lightn+ arre/] tap4 ,?is *oke coil is = ! purpose ( plac+ self-induction 9 ! circuit1 s t ! lightn+ w t5d to bran* (f ?r\gh ! lightn+ arre/] & to gr\nd1 r ?an to seek a pa? ?r\gh ! motor insulation to gr\nd4 ,illu/ration3 ,fig #cg4 ,diagram ( ,light ,circuit4 ,(t51 h[ev]1 ! *oke coil is omitt$1 ! coils 9 ! circuit break] & ! bl[-out coil 9 ! controll] be+ dep5d$ ^u to prev5t ! lightn+ *>ge f pass+4 ,lamp ,circuits4 ,! lamp circuit ( a c> is protect$ by its sep>ate fuse box1 & usually ea* lamp circuit has a swit*4 ,z expla9$ be=e1 five #ajj-volt or #aaj-volt lamps are plac$ 9 s]ies betwe5 ! trolley wire side ( ! circuit & gr\nd4 ,if "o lamp 9 ! s]ies burns out1 ( c\rse1 all five are ext+ui%$ until ! defective lamp is replac$ ) a new "o4 ,enclos$ arc lamps are sometimes us$ = c> light+4 ,c>s to be op]at$ f ei!r end are (t5 wir$ s t by turn+ a swit* ! plat=m light on ! front end1 a light = ! sign & ano!r = ! headlight on ! re> end w be ext+ui%$ & correspond+ lights on ! re> & front ends light$4 ,?is is accompli%$ by ! me?od ( wir+ %[n 9 ,fig4 #cg4 ,! int]ior ( ! c> is light$ by six lights4 ,headlights ( #cb c&le p[] are us$4 ,?is me?od requires ! use ( two swit*es4 ,9 all light wir+ s*emes a swit* %\ld be plac$ on ! trolley side ( ! lights4 ,?is p]mits ! curr5t to be cut (f 9 ! ev5t ( a gr\nd occurr+ 9 ! sy/em4 ,on int]urban c>s arc headlights are almo/ inv>iably us$4 ,! circuit = ! headlight aft] pass+ ?r\gh a swit* 9 ! motorman's cab goes ?r\gh a resi/ance frame usually und]nea? ! c> & t]m9ates 9 a socket ne> ! c> bump]4 ,! brackets on :i* ! lamp is hung are gr\nd$ s t :5ev] ! plug f ! lamp is ins]t$ 9 ! socket & ! swit* 9 ! cab is turn$ on1 ! circuit is made4 ,usually !re is a pressure ( ab\t #fj to #gj volts at ! t]m9als ( ! lamp4 ,! rema9d] ( ! voltage drop1 f #ejj or #fjj volts 7or :atev] ! l9e may be71 is 9 ! resi/ance "u ! c>4 ,! curr5t ?r\gh ! lamp is usually ab\t f\r amp]es4 ,) #fj volts at ! arc & #ejj volts on ! l9e1 ?is gives a consumption 9 ! lamp ( #bdj watts & a loss 9 ! resi/ance "u ! c> ( #b1jjj watts1 or ab\t #ij p] c5t4 ,! use ( ! headlight resi/ance to cut ! voltage d[n is !re=e a v ineffici5t me?od4 ,"s s*emes ( wir+ use ! inc&esc5t lamps us$ 9 light+ ! c> z resi/ance = ! headlight4 ,ano!r way is to light ! int]ior ( ! c> ) arc lamps plac$ 9 s]ies ) ! arc headlight4 ,trolley ,base4 ,! trolley base ^u :i* ! trolley pole swivels1 & :i* furni%es ! t5sion t holds ! trolley :eel aga9/ ! wire1 is design$ to ma9ta91 by means ( spr+s1 an approximately ev5 t5sion aga9/ ! trolley wire1 :e!r ! trolley wire is high above ! track or ne> ! c> ro(4 ,?is is done by *ang+ ! relative lev]age :i* ! spr+s ( ! trolley base h on ! trolley pole accord+ to ! height ( ! trolley pole4 ,illu/ration3 ,fig4 #ch4 ,trolley ,base4 ,illu/ration3 ,fig4 #ci4 ,trolley ,:eel4 ,fig4 #ch %[s "o =m ( trolley base4 ,! trolley base is bolt$ to a plat=m con/ruct$ = x on ! ro( ( ! c>2 & ! supply wire to ! motors & o!r electrical devices on ! c>1 except 9 cases :]e a wood5 trolley pole is us$ = c]ta9 special reasons1 is connect$ directly to ! trolley base4 ,an insulat$ trolley wire is run d[n ! wood5 trolley pole1 & connect$ ?r\gh a flexible lead to ! c> wir+4 ,trolley ,poles4 ,! trolley poles 9 g5]al use are ( tubul> /eel1 :i* gives ! greate/ /r5g? = a giv5 weight1 & :i* c usually be /raight5$ if ! pole has be5 b5t by /rik+ ov]head "w :5 ! trolley :eel leaves ! wire4 ,trolley ,:eels4 ,trolley :eels are f f\r to six in*es 9 diamet] ov] all1 ! small :eels be+ us$ 9 ! city s]vice1 & ! l>ge :eels 9 high spe$ int]urban s]vice4 ,a typical trolley :eel is %[n 9 ,fig4 #ci4 ,v>i\s companies use v>i\s =ms ( groove 9 ! trolley :eels1 "s adopt+ a groove approximately ,v-%ap$4 ,! ,u-%ap$ groove1 h[ev]1 is ! mo/ common4 ,! trolley :eel is made ( a brass composition select$ = its t\ghness & we>+ qualities4 ,illu/ration3 ,fig4 #dj4 ,trolley ,h>p4 ,trolley ,h>p4 ,! trolley h>p1 :i* is plac$ on ! end ( ! trolley pole & 9 :i* ! trolley :eel revolves1 usually has "s means = mak+ electrical contact ) ! :eel 9 addition to ! j\rnal be>+4 ,9 ! h>p illu/rat$ 9 ,fig4 #dj1 :i* is a typical =m1 ?is additional contact is secur$ by a spr+ be>+ aga9/ ! side ( ! hub ( ! :eel4 ,illu/ration3 ,fig4 #da4 ,?ird ,rail ,%oe4 ,s9ce trolley :eels revolve at a v high spe$1 "s unusual means ( lubrication mu/ be provid$1 s9ce !re is no opportunity = ord9>y oil or grease lubrication4 ,graphite1 9 ! %ape ( :at is call$ a 8graphite bu%+10 is mo/ commonly us$4 ,?is is a brass bu%+1 :i* is press$ into ! hub ( ! trolley :eel4 ,9 ?is bu%+ is a spiral groove fill$ ) graphite :i* is suppos$ to furni% suffici5t lubrication z ! bu%+ we>s4 ,roll]-be>+ trolley :eels h be5 us$ to a limit$ ext5t1 ) consid]able success 9 "s cases4 ,"s companies h done away ) ! graphite bu%+1 & h provid$ a v long j\rnal = ! trolley :eel in/ead ( ! usual %ort bu%+4 ,contact ,%oes4 ,! contact %oe mo/ commonly us$ on roads employ+ ! ?ird rail is %[n 9 ,fig4 #da4 ,?is is simply a %oe ( ca/ iron hung loosely by l9ks4 ,! weight ( ! %oe is suffici5t to give contact4 ,! motion ( ! l9ks p]mits ! %oe to accommodate itself to unusual ob/ructions & v>iations 9 ! height ( ! ?ird rail4 ,! %oe is fa/5$ to ! truck frame by means ( a wood5 plank :i* furni%es ! necess>y insulation4 ,illu/ration3 ,fig4 #db4 ,sleet ,:eel4 ,! ,pott] ?ird-rail %oe :i* has be5 us$ to a limit$ ext5t1 employs a spr+ = giv+ ! necess>y t5sion to make electrical contact betwe5 ! %oe & ! ?ird rail4 ,9 "s ways ?is is sup]ior1 because a spr+ t5sion is quick] 9 its action ?an gravity1 & ! %oe accommodates itself bett] to v>iations 9 ! height ( ! ?ird rail at v high spe$4 ,! we> on ! %oe1 h[ev]1 is likely to be great]4 ,sleet on ,trolleys & ,?ird ,rails4 ,! deposit ( sleet on trolleys & ?ird rails h9d]s greatly ! op]ation ( c>s4 ,(t5 sleet :eels ( ! type %[n 9 ,fig4 #db are us$ z a trolley :eel4 ,^! cut ! sleet (f in/ead ( roll+ ov] x4 ,on ! ?ird rail1 scrap]s & bru%es 9 advance ( ! contact %oe are usually effective :]e tra9s are frequ5t4 ,sev]al roads are n[ melt+ ! sleet on ! rails by ! use ( a solution ( calcium *loride4 ,! solution is /or$ 9 a tank on ! c> & is l$ ?r\gh small pipes to ! rail imm$iately 9 front ( ! collect+ %oe4 ,ab\t "o gallon ( solution is us$ p] mile1 mak+ ! co/ ab\t #g c5ts p] mile4 ,! effects ( "o treatm5t la/ = two or ?ree h\rs dur+ ! cont9uance ( a /orm4 ,solutions ( common salt h be5 us$ 9 ! same mann]1 b x is claim$ t ! corrod+ action on ! iron ( ! calcium *loride is n z great z t ( a salt solution4 ,,trucks4 ,electric railway c>s are classifi$ g5]ally z d\ble-truck & s+le-truck c>s4 ,d\ble-truck c>s are ^? t h a truck t swivels at ea* end ( ! c>4 ,a s+le-truck c> is "o hav+ f\r :eels4 ,illu/ration3 ,fig4 #dc4 ,brill #ba-;,e ,c> ,truck4 ,s+le ,trucks4 ,a great _m types ( s+le trucks h be5 design$4 ,x w\ld be out ( ! "q to discuss !m all "h4 ,9 g5]al1 h[ev]1 x may be said t truck build]s h aim$ to make a truck frame 9 itself a complete unit indep5d5tly ( ! c> body1 s t ! c> body w simply re/ ^u ! trucks & !re w be no /ra9 on ! c> body 9 ma9ta9+ ! alignm5t ( ! truck4 ,mo/ s+le trucks1 !re=e1 consi/ ( a rectangul> /eel frame1 ei!r ca/ or =g$1 rivet$ or bolt$ toge!r4 ,?is frame holds ! j\rnal boxes 9 rigid alignm5t4 ,usually a spr+ is plac$ betwe5 ea* j\rnal box & ! truck frame4 ,?is spr+ may be ei!r spiral or elliptic4 ,! pr9cipal spr+s1 h[ev]1 are betwe5 ! truck frame & ! c> body4 ,mo/ truck build]s h us$ a comb9ation ( spiral & elliptic spr+s betwe5 ! c> body & truck frame1 z ?is comb9ation is consid]$ to give bett] rid+ qualities & great] fre$om f teet]+ or gallop+ ?an ei!r spiral or elliptic spr+s alone4 ,fig4 #dc %[s a ,brill s+le truck1 :i* illu/rates all ( ! features enum]at$4 ,swivel ,trucks4 ,swivel trucks1 commonly call$ d\ble trucks1 are made 9 _m =ms1 b ! mo/ common is t kn[n z ! ,m4 ,c4 ,b4 type ( truck4 ,?is truck is simil> to ! /&>d truck :i* is 9 univ]sal use on /eam railroad pass5g] c>s 9 ! ,unit$ ,/ates4 ,diff]5t truck build]s h introduc$ _m v>iations 9 ?is g5]al type ( truck1 9 adapt+ x to electric s]vice4 ,"s modifications f ! /eam railroad /&>d truck 7 necess>y to accommodate ! electric motors & to p]mit 9 "s cases a l[-hung c> body4 ,su* trucks are made 9 a great v>iety ( sizes4 ,illu/ration3 ,fig4 #dd4 ,/4 ,l\is ,c> ,company ,truck4 ,fig4 #dd %[s "o ( ^! trucks built by ! ,/4 ,l\is ,c> ,company4 ,9 ?is type ( truck ! c> body is fa/5$ to ! truck only by ! k+bolt on :i* ! truck swivels4 ,?is k+bolt is plac$ 9 ! c5t] ( ! truck bol/]4 ,!re are also side be>+s betwe5 ! c> body & ! ends ( ! bol/]1 to prev5t tipp+ ( ! c> body :5 x is unbalanc$4 ,! arrangem5t ( ?is "p ( ! truck is %[n 9 ,fig4 #de4 ,"u ?is bol/] are elliptic spr+s :i* re/ on :at is call$ ! spr+ plank4 ,?is spr+ plank is hung f ! rectangul> frame ( ! truck by l9ks :i* all[ a side motion4 ,?is side motion gives easi] rid+1 especially ^u ent]+ & leav+ curves4 ,all trucks hav+ ?is feature are kn[n z sw+ bol/] trucks4 ,! weight1 be+ transmitt$ to ! transom & truck frame ?r\gh ! sw++ l9ks j ref]r$ to1 is !n tak5 by ! equaliz] spr+s t support ! rectangul> truck frame on equaliz+ b>s1 :i* equaliz+ b>s re/ on ! j\rnal box at ei!r end & are b5t d[n to accommodate ! spr+s locat$ betwe5 !m & ! truck frame4 ,! truck frame holds ! j\rnal boxes 9 alignm5t by means ( guides :i* p]mit an up-&-d[n movem5t )\t movem5t 9 any o!r direction1 j z on all o!r types ( truck4 ,x is ?us se5 t !re are two sets ( spr+s betwe5 ! c> body & c> j\rnals2 "o set ( spiral spr+s betwe5 ! equaliz+ b> & truck frame2 & "o set ( elliptic spr+s betwe5 ! spr+ plank & ! bol/]4 ,all %ocks mu/ be transmitt$ fir/ ?r\gh ! spiral spr+s & !n ?r\gh ! elliptic spr+s4 ,! motors us$ on ?is type ( truck usually h nose susp5sion1 ! nose ( ! motor re/+ ei!r on ! bol/] ( ! truck or on ! truck frame4 ,illu/ration3 ,fig4 #de4 ,bol/]1 ,l9ks & ,spr+ ,plank4 ,illu/ration3 ,fig4 #df4 ,/eel ,tire ,:eel4 ,!re are a numb] ( swivel trucks made :i* h dep>t$ consid]ably f ,m4 ,c4 ,b4 l9es1 b ne>ly all reta9 ! features ( a bol/] m\nt$ by spr+s on a spr+ plank1 a spr+ plank hung f a transom1 a transom rigidly fa/5$ to ! rectangul> truck frame ( :i* x =ms a "p2 & a truck frame ) "o or m sets ( spiral spr+s betwe5 x & ! j\rnal boxes4 ,maximum ,traction ,trucks4 ,a type ( swivel truck t once 0 v popul> b has l>gely be5 sup]s$$ by ! type j describ$ is ! 8maximum traction truck40 ,?is truck has two l>ge :eels on an axle :i* c>ries #fj to #gj p] c5t ( ! weight on ! truck1 & two small :eels c>ry+ ! balance ( ! weight4 ,! motors are on ! l>ge :eels4 ,c> ,:eels4 ,! c> :eels mo/ commonly us$ are ( ca/ iron4 ,9 ord] to make a tread & flange ^u :i* ! we> comes1 h>d en\gh to give a good mileage1 ! tread & flange are *ill$ 9 ! process ( ca/+4 ,ar\nd ! p]iph]y ( ! m\ld 9 :i* ! :eels are ca/1 is a r+ ( iron in/ead ( ! usual s&4 ,:5 ! molt5 ca/ iron comes 9 contact ) ?is r+ ( iron1 :i* is call$ a 8*ill10 ! iron is cool$ s sudd5ly t x becomes extremely h>d4 ,! balance ( ! :eel1 cool+ m sl[ly s9ce x is surr\nd$ by s&1 has ! h>dness ( ord9>y ca/ iron4 ,a /eel tire :eel is %[n 9 ,fig4 #df4 ,illu/ration3 ,fig4 #dg4 ,elevat$ ,c> ,axle4 ,:eels ) /eel tires are com+ into use = elevat$ & int]urban c>s because _! flanges are n s brittle z ^? ( ca/-iron :eels4 ,9 :eels ( ca/ metal !re is always a liability t ! flanges & tread w *ip & crack4 ,on high-spe$ c>s ! fall+-out ( pieces ( flange may be a s]i\s matt] & result 9 a wreck4 ,/eel-tir$ :eels h a hub & spokes ei!r ( ca/ or =g$ /eel or iron4 ,on to ?is :eel a /eel tire is %runk4 ,! tire is heat$ 9 a furnace built = ! purpose1 & is !n slipp$ ov] ! :eel4 ,x is made j su* a size t x w slip ov] ! :eel :5 hot1 & :5 x is cool x w %r9k en\gh to make a v tight fit4 ,:5 ! tire is to be remov$ aft] x is worn out1 x is heat$ until x has exp&$ suffici5tly to drop (f4 ,an axle = elevat$ c> is %[n 9 ,fig4 #dg4 ,:5 ca/-iron :eels are worn to an improp] %ape or h flat spots ^u !m1 due to ! slid+ ( ! :eels ) ! brakes set1 an em]y :eel gr9d] mu/ be us$ to gr9d !m d[n1 z no?+ else is h>d en\gh to h any effect on ! iron4 ,illu/ration3 ,fig4 #dh4 ,/&>d ,m4 ,c4 ,b4 ,flange4 ,:5 /eel-tir$ :eels are worn1 !y c be put 9 a la! & ! surface ( ! tire turn$ (f1 z ?is surface is ( metal s(t en\gh to be workable ) ord9>y tools4 ,illu/ration3 ,fig4 #di4 ,brake ,%oes & ,lev]s4 ,! types ( :eel tread & :eel flange 9 use v>y greatly among diff]5t electric railways4 ,!re is a /&>d ,ma/] ,c> ,build]s' :eel tread us$ on /eam railroads1 :i* is %[n 9 ,fig4 #dh4 ,electric railways1 h[ev]1 are usually oblig$ to use a small] flange & n>r[] tread4 ,/reet railway special "w1 su* z swit*es & cross+s1 usually has too %all[ a flange way to p]mit a /&>d ,m4 ,c4 ,b4 flange to pass ?r\gh4 ,"s /reet railways use flanges z %all[ z -in*1 al?\gh -in* is mo/ common on city "w4 ,! wid? ( ! tread on /reet railway c>s1 t is1 ! wid? ( ! :eel :]e x be>s on ! rail1 is usually f #a in*es to #b in*es4 ,!re is a t5d5cy1 h[ev]1 on electric railways1 on acc\nt ( ! increas+ numb] ( int]urban c>s :i* mu/ use city tracks1 to build tracks t w accommodate :eels approa*+ ! ,m4 ,c4 ,b4 /&>d ( /eam roads4 ,a few roads h adopt$ :eel treads & flanges v ne> to ! ,m4 ,c4 ,b4 /&>d4 ,illu/ration3 ,,automatic ,,air ,,brake ,,cab ,,equipm5t4 ,we/+h\se ,air ,brake ,co4 ,brake ,rigg+4 ,! brake rigg+ on a s+le-truck c> may be arrang$ 9 a v>iety ( ways1 b %\ld be su* t a ne>ly equal pressure w be br\ght to be> on ! brake %oes on all f\r :eels4 ,a typical arrangem5t ( brake %oes & lev]s = s+le-truck c>s is %[n 9 ,fig4 #di4 ,! rods ,r t]m9ate 9 *a9s w9d+ ar\nd ! brake /aff ^u :i* ! motorman's h&le or h& :eel is m\nt$4 ,illu/ration3 ,fig4 #ej4 ,brake ,lev]s & ,air ,brake4 ,= d\ble-truck c>s ! brake rigg+ is necess>ily m complicat$1 z x mu/ be arrang$ to give an equal pressure on all eight :eels ( ! c>4 ,brake %oes are sometimes plac$ betwe5 ! :eels ( a truck & sometimes outside4 ,! arrangem5t ( brake %oes betwe5 :eels is app>5tly f9d+ mo/ favor1 z :5 ! %oes are appli$ 9 ?is position !re is less t5d5cy to tilt ! truck frame :5 ! brakes are appli$1 & ?is adds to ! com=t ( pass5g]s 9 rid+4 ,fig4 #ej %[s "o =m ( arrangem5t ( brake lev]s common on a d\ble-truck c> equipp$ ) air brakes1 ) inside-hung brake %oes4 ,brake ,lev]ages & ,%oe ,pressure4 ,! lev]s betwe5 ! air cyl9d] & ! brake %oes are usually s proportion$ t ) an air pressure ( #gj lbs4 p] sq4 94 9 ! brake cyl9d]s ! total ( ! brake %oe pressures on ! :eels w be equal to ab\t #ij p] c5t ( ! weight ( ! c>4 ,! diagram ,fig4 #ea has %oe pressures & /ra9s 9 ! sev]al rods m>k$ on %oes & rods4 ,! foll[+ example1 bas$ on ! diagram1 w expla9 ! lev] proportion+4 ,only r\nd numb]s are giv5 on ! diagram4 ,assume a f\r-motor c> weigh+ #dj1jjj p\nds4 ,a brake cyl9d] #g in*es 9 diamet] is us$4 ,?is gives #ch4e squ>e in*es & at #gj p\nds air pressure a total =ce on ! pi/on rod ( #b1fie p\nds4 ,! weight ( ! c> is #dj1jjj p\nds4 ,tak+ #ij p] c5t ( ?is gives a total ( #cf1jjj p\nds to be ex]t$ by ! brake %oe :5 an em]g5cy /op is made4 ,ea* ( ! eight %oes w press aga9/ ! :eels ) a =ce ( #d1ejj p\nds4 ,! dim5sions ( ! truck are su* t ! 8dead lev]s10 ^? fix$ at "o end & :i* c>ry %oes1 _c be ov] #ac in*es long4 ,! %oe w be hung ?ree in*es f "o end1 mak+ ! proportions #aj to #c1 & ! pressure on ! /rut rod betwe5 %oes w be #d1ejj or #c1dfa p\nds4 ,to cle> ! truck frame ! live lev] ext5ds #ad in*es above ! po9t ( application ( ! brake %oe4 ,to obta9 #d1ejj p\nds pressure on ! %oe1 ! di/ance betwe5 ! brake %oe & ! /rut rod1 :i* we w call 8x10 w be f\nd by reg>d+ ! upp] end ( ! lev] z fix$ & ! p[] appli$ at ! l[] end4 #ad x #dejj #cdfa ---------------- or #ad x #d4b in*es4 ,n[ to obta9 ! =ce requir$ 9 ! rod to ! truck quadrant1 ! bottom end ( ! live lev] mu/ be reg>d$ z ! fulcrum4 ,! equation is #d4b x #dejj -------- #ajch p\nds4 #ah4b ,z ! pull rods f ea* side ( ! truck are atta*$ to ! truck quadrant1 ! /resses 9 ! brake rods are d\ble ?is1 or #b1jgf p\nds4 ,illu/ration3 ,fig4 #ea4 ,diagram ( ,brake ,%oe ,pressures & ,/ra9s4 ,! position ( ! brake cyl9d] "u ! c> re/ricts ! l5g? ( ! 8live0 & 8dead0 cyl9d] lev]s to #af in*es4 ,to obta9 #b1jgf p\nds pull on "o end ( ! lev]s ) ! previ\sly comput$ #b1fie #bjgf x p\nds on ! o!r1 ! proportions mu/ be -------- ------1 s9ce #bjgf #dgga #af #bfie #dgga4 ,!n x #g in*es1 ! di/ance f ! brake pi/on to ! pivotal po9t4 ,s9ce #b1fie p\nds pressure is ex]t$ & #cf1jjj p\nds results ! proportion ( ! :ole sy/em ( lev]s is #cf1jjj to #b1fie or #ac4c to #a4 ,9 o!r words ! travel ( ! pi/on 9 ! cyl9d] w be #ac4c times t ( ! %oes if !re 7 no lo/ motion to be tak5 up4 ,! pi/on travel %\ld be f #d to #e in*es4 ,?is gives ab\t -in* travel ( ! brake %oes4 ,increas$ travel ( ! brake %oes necess>y to set !m z !y we> away causes increas$ travel ( ! pi/on ( ! air cyl9d]4 ,n only is m air us$ at ea* application ( ! brakes b ! brakes are sl[] 9 act+4 ,x is !re=e necess>y to adju/ ! brakes frequ5tly4 ,?is is done 9 ! sy/em %[n 9 ! diagram by ! use ( a turnbuckle 9 ! connect+ rod betwe5 ! live & dead lev]s ( ! truck4 ,:5 two motors are on "o truck & none on ! o!r1 all[ance mu/ be made 9 ! lev]s = ! increas$ weight ( ! motor truck & ! in]tia ( ! armature4 ,! lev]age on ! motor truck mu/ be great] ?an on ! o!r4 ,air ,brakes4 ,air brakes us$ on electric railway c>s are usually ( :at is call$ ! /raight air brake type 9 di/9ction to ! ,we/+h\se automatic air brake4 ,a /raight air brake is "o 9 :i* ! air is /or$ 9 a res]voir2 &1 :5 ! brakes are to be appli$1 air f ?is res]voir is turn$ directly into ! brake cyl9d]1 9 :i* works a pi/on op]at+ ! brake lev]s4 ,air admitt$ beh9d ! pi/on =ces x out ) a pressure :i* applies ! brakes4 ,:5 ! air is let out ( ! brake cyl9d]1 a spiral spr+ =ces ! pi/on back to its orig9al position & ! brakes are releas$4 ,! motorman's valve by :i* he applies ! brakes1 !re=e1 provides1 fir/1 = turn+ air f ! /orage res]voir to ! brake cyl9d] to apply ! brakes1 &1 second1 = clos+ ! op5+ to ! /orage res]voir & op5+ an exhau/ passage f ! brake cyl9d] s t ! air c escape f ! brake cyl9d] to release ! brakes4 ,/raight air brakes ( ?is k9d w\ld n be suit$ to ! op]ation ( long tra9s1 because1 if ! air-brake hose connection betwe5 c>s %\ld be brok51 ! brakes w\ld be useless2 b = tra9s ( "o or two c>s1 su* z are common 9 electric railway practice1 ! simplicity ( ! /raight air brake outweighs its disadvantages & ?is is ! type ( brake usually employ$4 7,see ,fig4 #eb47 ,! ,we/+h\se & o!r =ms ( automatic air brake are us$ on electric railways :]e c>s are op]at$ 9 long tra9s2 b x is out ( ! prov9ce ( ?is pap] to describe ^! brake sy/ems fully1 z !y are r complicat$4 ,x may be said 9 g5]al1 h[ev]1 t ! ,we/+h\se automatic air brake is s arrang$ t1 %\ld ! hose connection betwe5 c>s be brok51 %\ld ! tra9 pull 9 two1 or %\ld any?+ happ5 to r$uce ! pressure :i* is ma9ta9$ 9 ! tra9 pipe t runs ! l5g? ( ! tra91 ! brakes w\ld imm$iately be appli$ on ! entire tra94 ,illu/ration3 ,fig4 #eb4 ,diagram ( ,/raight ,air ,equipm5t4 ,compressors4 ,a small air compressor driv5 by an electric motor is frequ5tly employ$ on electric c>s to keep ! /orage res]voir ( ! c> suppli$ ) air4 ,^! air compressors are c>ri$ "u ! c> or 9 ! motorman's cab4 ,!y are g5]ally arrang$ ) an automatic device :i* closes ! motor circuit & />ts ! motor z soon z ! air pressure falls bel[ a c]ta9 am\nt2 & ! motor w cont9ue 9 op]ation pump+ air until ! pressure rises to ! am\nt = :i* ! automatic device is set4 ,! pressure c>ri$ 9 ! /orage res]voir is usually f #fj to #ij p\nds p] squ>e in*1 :i*1 z a g5]al ?+1 is consid]ably m ?an is requir$ to apply ! brakes h>d en\gh to slide ! :eels4 ,automatic ,gov]nor = ,air ,compressors4 ,automatic gov]nors are (t5 in/all$ 9 connection ) air compressors 9 ord] t a fairly ev5 air pressure may be ma9ta9$ 9 ! /orage res]voir4 ,9 ^! ! fall & rise ( ! air pressure )9 c]ta9 limits closes & op5s ! circuits to ! motor4 ,9 "s /yles ! air act+ on a pi/on op]ates ! circuit break]4 ,! diagram %[n 9 ,fig4 #ec %[s ! pr9ciple ( ! ,*ri/5s5 gov]nor1 9 :i* ! air pressure is employ$ to make & break a second>y circuit4 ,:5 ! pressure 9 ! /orage res]voir falls bel[ a pr$et]m9$ value1 ! h& ( ! air gauge makes contact ) lug ,a4 ,?is closes ! circuit ?r\gh sol5oid ,no4 #a4 ,lug ,d1 me*anically connect$ to ! armature ( ! sol5oids is pull$ 9 contact ) lug ,c1 & ?is closes ! circuit to ! motor1 & %unts ! w9d+ ( sol5oid ,no4 #a4 ,:5 ! air pressure rises to a pr$et]m9$ value ! h& ( ! air gauge is ?r[n 9 contact ) lug ,b4 ,?is en]gizes sol5oid #b by connect+ x across ! motor t]m9als4 ,! armature is pull$ to ! "r & ! circuit to ! motor is brok54 ,:5 ?is is done x is evid5t t ! curr5t ?r\gh ! en]giz$ sol5oid is brok54 ,x is evid5t f ! description t curr5t passes ?r\gh ! sol5oids only dur+ ! %ort p]iods t ! armature is mov+ f "o position to ! o!r & ! air gauge nev] has to break a circuit 9 :i* !re is an appreciable voltage s t !re is no arc+ at lugs ,a & ,b4 ,illu/ration3 ,fig4 #ec4 ,a bl[-out coil 9 s]ies ) ! motor is provid$ imm$iately "u lug ,c :i* ext+ui%es ! arc at t po9t :5 ! motor circuit is brok54 ,a ,we/+h\se air compressor is %[n 9 ,fig4 #ed4 ,/orage ,air ,brakes4 ,! /orage air-brake sy/em does n h a small indep5d5t compressor on ea* c>1 b is equipp$ ) a l>ge /orage tank1 9 :i* air is c>ri$ "u high pressure--#bej to #cjj p\nds p] squ>e in*4 ,?is /orage tank is fill$ at regul> int]vals :5 ! c> passes "s po9t on its r\te at :i* a compressor is locat$4 ,9 ?is case ! c> is oblig$ to /op long en\gh to make connection to ! tank ( ! compressor plant1 & to all[ ! c> /orage tank to be fill$4 ,?is op]ation1 h[ev]1 does n take long4 ,! advantages ( ! sy/em are a sav+ ( ! weight & a sav+ 9 ! ma9t5ance ( a small compressor on ea* c>4 ,f ! ma9 /orage tank "u ! c>1 air is l$ ?r\gh a r$uc+ valve to an auxili>y /orage tank4 ,?is r$uc+ valve all[s en\gh air to pass ?r\gh to ma9ta9 a pressure ( ab\t #ej p\nds p] squ>e in* 9 ! auxili>y /orage tank4 ,! auxili>y /orage tank corresponds to ! regul> /orage tank on a sy/em employ+ compressors on ea* c>4 ,! me?od ( op]ation aft] ! air has ent]$ ! auxili>y /orage tank is ! same z ) any air-brake sy/em4 ,illu/ration3 ,fig4 #ed4 ,we/+h\se ,air ,compressor4 ,fig4 #ee %[s ! arrangem5t ( ! app>atus "u ! c>s ( ! ,/4 ,l\is ,transit ,company4 ,! two /orage tanks are ea* #f feet long by #ah in*es 9 diamet] & are m\nt$ "o on ea* side ( ! c>4 ,_! comb9$ capacity is equival5t to ab\t #ajj cubic feet at #de lbs4 pressure4 ,! tanks are *>g$ ?r\gh an outlet ne> "o side ( ! c>4 ,?is outlet conta9s a *eck valve & cock to prev5t leakage4 ,! s]vice or l[ pressure res]voir has a capacity ( ab\t #b cubic feet4 ,! position ( ! r$uc+ valve betwe5 ! high & l[ pressure valves may be not$ 9 ! illu/ration4 ,mom5tum ,brakes4 ,mom5tum or friction brakes h be5 us$ to "s ext5t bo? on s+le-truck & on d\ble-truck c>s1 b p>ticul>ly on s+le-truck c>s4 ,!y d]ive ! p[] to op]ate ! brakes f ! mom5tum ( ! c> by means ( a friction clut* on ! c> axle4 ,! diff]5ce 9 v>i\s k9ds ( mom5tum brakes lies *iefly 9 ! design ( ! clut* me*anism4 ,! clut* mu/ evid5tly be arrang$ to act v smoo?ly1 & mu/ be "u v accurate control1 z ! =ce ) :i* ! brakes are appli$ dep5ds directly ^u ! pull ex]t$ by ! clut*4 ,illu/ration3 ,fig4 #ee4 ,arrangem5t ( ,/orage ,air ,brake ,app>atus4 ,9 ! ,price mom5tum brake a flat disc is ca/ on ! c> :eel1 :i* is turn$ (f to a smoo? surface4 ,aga9/ ?is disc a friction clut* acts1 :i* has a lea!r face4 ,! clut* is op]at$ by a motorman's lev] ?r\gh a set ( lev]s4 ,a small movem5t 9 ! motorman's lev] =ces ! clut* aga9/ ! disc on ! c> axle4 ,! clut* w9ds up ! brake *a91 & ?us supplies p[] to apply ! brakes4 ,o!r mom5tum or friction clut* brakes h be5 devis$1 mo/ ( :i* also use an application ( lea!r on iron = ! clut*1 z ?is has be5 f\nd to be mo/ reliable1 & to be lea/ affect$ by ! grease & dirt t is liable to "w 9 betwe5 ! clut* surfaces4 ,g4 ,e4 ,electric ,brake4 ,! ,g5]al ,electric ,company's electric brake makes use ( curr5t g5]at$ by ! motors act+ z dynamos1 to /op ! c>4 ,9 ord] to accompli% ?is1 a brake controll] is provid$ :i* rev]ses ! armature connections ( ! motors1 & s connects !m to op]ate z dynamos s5d+ curr5t ?r\gh a resi/ance 9 ! circuit2 ! am\nt ( curr5t fl[+ & ! brak+ effect dep5d+ on ! c> spe$ & ! resi/ance4 ,9 "s =ms ( brake controll]1 ! two controll]s are comb9$ 9 "o cyl9d]1 s t ! motorman1 to apply ! electric brake1 simply cont9ues ! movem5t ( ! h&le pa/ ! 8(f0 position4 ,9 o!rs1 ! brake-controll] drum is sep>ate1 b is int]lock$ ) ! ma9 controll] s t x c be us$ only :5 ! ma9 controll] is (f4 ,h[ev] ! controll] may be arrang$1 ! pr9ciple involv$ is t :5 ! motors are revolv+ by ! motion ( ! c>1 & ! armature connections are rev]s$ z !y w\ld be to rev]se ! direction ( motion ( ! c>1 ! motors beg9 to g5]ate curr5t z s]ies-w\nd dynamos4 ,! am\nt ( curr5t g5]at$ & ! ret>d+ effect w dep5d on two ?+s--namely1 ! spe$ ( ! c>1 ) ! consequ5t electromotive =ce 9 ! motors1 & ! am\nt ( resi/ance 9 ! circuit4 ,! am\nt ( resi/ance is regulat$ by ! motorman by means ( 8 electric brake controll]4 ,! function ( ! electric brake controll] is to rev]se ! motors & to ins]t en\gh resi/ance 9 ! circuit to make a com=table /op4 ,?is curr5t 9 ! motors act+ z dynamos1 9 itself acts z a p[]ful brake to ret>d ! motion ( ! c>4 ,9 ! ,g5]al ,electric type ( electric brake1 ! curr5t g5]at$ 9 ! motors1 9 addition to hav+ ?is ret>d+ effect 9 ! motors !mselves1 is conduct$ to brake discs t act z magnetic clut*es aga9/ "o ( ! c> :eels on ea* axle4 ,! c> :eel has a disc ca/ ^u x1 & aga9/ ?is ! magnetic disc acts4 ,! magnetic disc conta9s a coil :i* is 9 s]ies 9 ! brake circuit4 ,9 apply+ an electric brake ( ?is k9d ! motorman fir/ puts ! controll] on a po9t t ins]ts consid]able resi/ance 9 ! circuit4 ,:5 ! motors h sl[$ d[n1 ! electromotive =ce1 ( c\rse1 drops1 s t to ma9ta9 ! same brak+ curr5t !re mu/ be a r$uction ( ! am\nt ( resi/ance1 until1 :5 ! c> is almo/ at a /&/ill1 ! resi/ance is ne>ly all cut out4 ,x might seem at fir/ t ! curr5t w\ld die d[n be=e ! c> came to a /op1 b x is f\nd t !re is en\gh induction 9 ! motor fields to cause curr5t to fl[ = a %ort "t aft] ! c> has /opp$4 ,! residual magnetism 9 ! /eel 9 ! fields ( ! motor is suffici5t to cause ! motors to beg9 to g5]ate curr5t :5 ! electric-brake controll] is fir/ turn$ on4 ,! greate/ advantage ( an electric brake us+ motors z g5]ators is 9 ! fact t ! brak+ curr5t in/antly falls 9 value z soon z ! :eels beg9 to slide1 & releases ! brake until ! :eels aga9 revolve4 ,9 fact1 x is almo/ impossible to skid ! :eels z !y are sometimes skidd$ by be+ lock$ by brake %oes4 ,?is n only prev5ts flat :eels b insures a quick /op1 because :5 ! :eels are lock$ & slid+1 ! brak+ or ret>d+ p[] is only ab\t "o-?ird :at x 0 be=e ! :eels began to slide4 ,! electric brake requires extra l>ge motors because ( ! heat+ caus$ by ! curr5t g5]at$ :ile brak+4 ,illu/ration3 ,fig4 #ef4 ,magnetic ,brake ,%oe4 ,we/+h\se ,electromagnetic ,brake4 ,! ,we/+h\se magnetic brake is 9 pr9ciple simil> to ! ,g5]al ,electric brake z f> z ! use ( motors z g5]ators is conc]n$2 b1 in/ead ( assi/+ ! motors by means ( a magnetic brake disc act+ aga9/ ! c> :eel1 a magnetic brake %oe is us$ 7see ,fig4 #ef71 :i* acts aga9/ bo? c> :eel & track4 ,?is n only ret>ds ?r\gh ! m$ium ( ! :eels b acts directly on ! track4 ,x is n dep5d5t ^u ! coeffici5t ( friction betwe5 ! :eels & track2 & x %\ld1 !re=e1 be possible to /op mu* m quickly ?an ) any =m ( brake dep5d+ ^u ! coeffici5t ( friction betwe5 ! :eels & track4 ,illu/ration3 ,,magnetic ,,brake ,,%[+ ,,me?od ,,( ,,atta*+ ,,to ,,c> ,,frame ,,& ,,trucks4 ,we/+h\se ,air ,brake ,co4 ,track ,brakes4 ,track brakes h be5 us$ to "s ext5t on v hilly electric roads4 ,^! h a %oe fa/5$ to ! truck frame1 :i* acts directly on ! track4 ,motors z ,em]g5cy ,brakes4 ,! motors c ( c\rse be us$ to brake ! c> by simply rev]s+ !m if curr5t is appli$ to !m f ! l9e4 ,b 9 case ! trolley flies (f or if ! circuit break] or ! fuse op5s ! circuit1 or ! supply ( curr5t is int]rupt$ = any o!r reason1 !y may be us$ z brakes by ?r[+ ! rev]se lev] & mov+ ! controll] h&le to ! multiple position ( a two-motor equipm5t or by simply ?r[+ ! rev]se lev] ( a f\r-motor equipm5t4 ,^! movem5ts ?r[ ! motors 9 multiple & connect ! fields & armatures ( ! motor 9 su* relation t !y c g5]ate curr5t4 ,"o ( ! motors !n acts simil>ly to a g5]ator 9 a p[] h\se1 d]iv+ its p[] f ! mom5tum ( ! mov+ c> in/ead ( f an eng9e1 & s5ds curr5t ?r\gh ! o!r motor ( ! pair :i* acts l any auxili>y motor try+ to revolve its :eels 9 ! opposite direction f t 9 :i* !y are revolv+4 ,! motors ( a f\r-motor equipm5t are p]man5tly connect$ 9 two multiple gr\ps z long z ! rev]se is n 9 ! c5tral position4 ,9 ! two motor equipm5t su* connections are n made until ! controll] h&le is turn$ to ! multiple position4 ,z ! ext]nal resi/ance is beyond ! junction ( ! two motor circuits1 ! brak+ effect is n increas$ by cutt+ out ! resi/ance4 ,! diff]5ce 9 ! residual magnetism ( ! fields or 9 ! magnetic qualities ( ! fields ( ! two motors is prim>ily ! cause ( ! g5]ation ( ! curr5t4 ,! motors at fir/ act 9 opposition1 b "o ( !m g5]ates ! high] voltage & =ces a curr5t ?r\gh ! o!r4 ,?is curr5t ov]comes ! residual magnetism ( ! second motor1 !reby *ang+ its pol>ity & bo? motors !n act 9 s]ies to s5d ! curr5t ?r\gh ! l[ resi/ance pa? af=d$ by ! w9d+s4 ,any curr5t pass+ increases ! /r5g? ( ! fields & consequ5tly ! voltages1 s t abnormal curr5ts are g5]at$ & ! brak+ action is consequ5tly sev]e4 ,?is g5]at+ action does n take place be=e ! rev]se lev] is ?r[n because ! connections ( ! armatures & fields are su* t any curr5t g5]at$ by reason ( ! residual magnetism ( ! fields1 fl[s 9 su* a direction ?r\gh ^! t ?is magnetism is de/roy$4 ,! curr5t !n ceases to fl[4 ,?is expla9s :y curr5t is n g5]at$ 9 ,no4 #b motor ) a ,k type ( controll] dur+ ! *ange-ov] p]iod :5 x is %ort-circuit$1 or 9 equipm5ts :5 ! trolley flies (f & ! controll] is turn$ on4 ,illu/ration3 ,fig4 #eg4 ,pneumatic ,s&]4 ,brake ,%oes4 ,! subject ( brake %oes is ( v little importance on ! small] c>s travel+ at sl[ spe$s & controll$ alone by h& brakes4 ,on ! l>g] high spe$ int]urban c>s1 ! brake %oe "q becomes an important item because ( ! rapidity ) :i* !y are worn away4 ,on su* c>s %oes sometimes la/ b ab\t "o week4 ,?is means eight %oes p] week p] c> or an exp5se ( ab\t #d4jj p] c> p] week4 ,brake %oes are usually ( s(t gray ca/ iron ) ins]ts ( /eel1 al?\gh "s companies use v h>d iron4 ,!y are usually fa/5$ by means ( a key to a brake %oe head p]man5tly atta*$ to ! brake rigg+4 ,! brake lev]s are s adju/$ t ! %oes cle> ! :eels ab\t -in* :5 ! brakes are releas$4 ,?is di/ance increases z ! %oes we>1 s t ! brakes mu/ be adju/$ frequ5tly to take up ! slack & prev5t wa/e ( air4 ,track ,s&]s4 ,a spr9kl+ ( s& on ! rail increases wond]fully ! adhesion ( ! rail & :eel4 ,!re is usually on c>s "s provision made = scatt]+ s& on ! rails imm$iately 9 front ( ! lead+ :eels4 ,f s& boxes plac$ "u ! seats 9 ! small] c>s1 or on ! truck ( ! l>g] ones1 flexible hose or pipes drop )9 an in* or two ( ! rail 9 front ( ! lead+ :eels4 ,a valve "u ! control ( ! motorman regulates ! fl[ ( s& to ! rail4 ,sometimes air pressure is us$ to bl[ ! s& out ( ! s& box into ! hose4 ,9 ?is case air pressure is obta9$ f ! air brake sy/em1 & an air valve lead+ to ! s& box is plac$ 9 ! motorman's cab4 ,a section ?r\gh a pneumatic s&] ( ?is k9d is %[n 9 ,fig4 #eg4 ,illu/ration3 ,fig4 #eh4 ,curves ( ,brak+ ,te/s4 ,coeffici5t ( ,friction4 ,x has be5 f\nd by exp]im5t t ! coeffici5t ( friction betwe5 ! c> :eel & rail is ab\t #be p] c5t ( ! weight on ! :eel :5 ! rails are dry2 t is1 a c> :eel hav+ a weight ( #b1jjj p\nds ^u x w\ld n be able to ex]t ei!r an accel]at+ or a ret>d+ =ce exce$+ #be p] c5t ( ?is1 or #ejj p\nds4 ,?is is :5 ! :eel is roll+4 ,!re is app>5tly a k9d ( lock+ or int]-me%+ ( ! r\gh surfaces ( :eel & rail :5 ! :eel is roll+1 because x is f\nd t :5 a :eel beg9s to skid or slide1 ! coeffici5t ( friction falls (f ab\t two-?irds4 ,! maximum brak+ or ret>d+ =ce t c be obta9$1 !re=e1 9 a dry rail1 am\nts to #be p] c5t ( ! weight ( ! c>4 ,if ! rail is slipp]y ?is is mu* r$uc$2 or if ! :eels are all[$ to slide x is also mu* r$uc$4 ,if m ret>d+ =ce ?an c be obta9$ ?r\gh ! m$ium ( a :eel roll+ on ! rail is desir$1 x mu/ be obta9$ ei!r by ! track brakes or by magnetism4 ,illu/ration3 ,fig4 #ei4 ,automatic ,c\pl]4 ,rate ( ,ret>dation 9 ,brak+4 ,! rate ( ret>dation ( c>s 9 brak+ is usually #a to #b miles p] h\r p] second4 ,9 o!r words a c> go+ at a spe$ ( #dj miles an h\r w usually be /opp$ 9 #dj to #bj seconds4 ,! plott$ results ( "s brak+ te/s 7,fig4 #eh7 %[ a high] rate ( accel]ation4 ,^! te/s 7 made on an int]urban c> weigh+ ab\t #fc1jjj p\nds1 equipp$ ) /raight air brakes4 ,( ! six curves %[n1 t giv+ ! highe/ rate ( ret>dation is ,no4 #d4 ,?is %[s a /op f a spe$ ( #ch miles p] h\r 9 #i seconds or a rate ( ret>dation ( ab\t #d miles p] h\r p] second4 ,all ( ! curves %[n are = em]g5cy /ops4 ,!y %[ ab\t ! highe/ rate ( ret>dation t c\ld be made ) ! equipm5t4 ,drawb>s & ,c\pl]s4 ,= small surface c>s a crude drawb> is usually provid$ consi/+ simply ( a /raight iron b> pivot$ "u ! c> & provid$ ) a ca/-iron pocket ne> ! end4 ,a c\pl+ p9 pass+ ?r\gh ! pocket ( "o c\pl] & ?r\gh a hole 9 ! end ( ! b> ( ! o!r1 holds ! two c>s toge!r4 ,! requirem5ts ( a c\pl] = heavi] c>s su* z ^? us$ on int]urban & elevat$ roads are m exact+4 ,! ends ( ! b>s are usually pivot$ "u ! c> ab\t five feet back f ! bump]4 ,a spr+ cu%ion int]v5es betwe5 ! pivot po9t & ! drawb> head4 ,! illu/rations1 ,figs4 #ei & #fj1 %[ ! action ( ! ,van ,dorn ,automatic c\pl]1 :i* is ! "o us$ by all ! elevat$ l9es 9 ! ,unit$ ,/ates4 ,! l9k is plac$ 9 "o ( ! drawb> heads & ! p9 9 ! o!r4 ,z ! c>s come toge!r ! w$ge-%ap$ end ( ! l9k =ces its way betwe5 ! p9 & a spr+4 ,:5 ! faces ( ! drawb> heads meet1 ! spr+ =ces ! l9k to engage ! p94 ,! me*anism is design$ especially to prev5t lo/ motion betwe5 c\pl] heads because1 unlike /eam railroad drawb>s1 electric c> drawb>s mu/ swivel to r\nd curves & a great am\nt ( play at ! po9t ( c\pl+ ) swivel+ drawb>s w\ld all[ ! c\pl]s to b5d "u a pu%+ /ra94 ,illu/ration3 ,fig4 #fj4 ,,c> ,,con/ruction4 ,c> ,bodies4 ,9 cities !re are ?ree g5]al types 9 common use2 namely1 box c>s1 suit$ = w9t] use only2 op5 c>s1 suit$ = summ] use only2 & semi-conv]tible c>s1 :i* c be adapt$ to ei!r summ] or w9t] use4 ,! op5 & box c>s are ! old] types4 ,! semi-conv]tible c> is usually provid$ ) a c5t] aisle1 & cross seats on ea* side ( ?is aisle4 ,illu/ration3 ,fig4 #fa4 ,side ,elevation & ,plan ( ,c>4 ,! w9d[s are l>ge1 s t !y c be l[]$ or rais$ 9 summ] to make some?+ approa*+ ! "* ( an op5 c>4 ,! c> bottom1 :i* =ms ! basis = ! entire c> /ructure1 is con/ruct$ ) longitud9al sills ei!r ( /eel or ( wood comb9$ ) /eel4 ,"o =m ( con/ruction employs z ! ma9 supports two /eel *annel b>s ext5d+ ! full l5g? ( ! c>4 ,/eel ,i-beams are sometimes us$4 ,:]e wood is us$ 9 comb9ation ) /eel = longitud9al sills1 ! /eel is usually 9 ! =m ( flat /eel plates betwe5 ! timb]s4 ,mo/ c>s seat ab\t "o pass5g] p] foot ( l5g? ov] all4 ,illu/ration3 ,fig4 #fb4 ,cross-,section ( ,c> ,body4 ,_m m difficulties are met 9 ! con/ruction ( pass5g] c>s = electric railways ?an 9 /eam coa* con/ruction4 ,! electric c> mu/ h l[ /eps & plat=ms & turn %ort curves4 ,! difficulties are l>gely 9 ! floor fram+ ( ! c>4 ,! plat=ms at ea* end are usually eight to t5 in*es l[] ?an ! floor ( ! int]ior4 ,z ! c> mu/ frequ5tly be design$ to pass ar\nd curves ( small radius1 (t5 ( only ?irty or =ty feet1 suffici5t cle>ance mu/ be provid$ = ! sw+ ( ! trucks4 ,?is necessitates t ! trucks ( a d\ble truck c> be set f> en\gh back t[>ds ! c5t] ( ! c> to cle> ! dropp$ plat=m timb]s1 %[n 9 ,fig4 #fc4 ,9 ! illu/ration %[n1 ,fig4 #fa1 ! truck c5t]s are b #ba feet #h in*es ap>t1 :ile ! ends ov]hang ! truck c5t]s #aa feet #d in*es4 ,x is difficult to support ?is ov]hang+ weight prop]ly4 ,! difficulty is increas$ by ! fact t ! re> plat=m is (t5 cr[d$ ) pass5g]s hav+ an aggregate weight ( "o ton or m4 ,trusses manife/ly _c be employ$ to give rigidity to ! long plat=m4 ,?is is usually giv5 9 c>s ( wood con/ruction by re9=c+ ! plat=m timb]s ) /eel plates z %[n 9 ! figure4 ,9 ord] t ! dropp+ t5d5cy ( ! plat=m %all n b[ up ! body ( ! c> betwe5 ! trucks ?is portion mu/ be brac$ rigidly4 ,! space bel[ ! w9d[s & above ! side sill is utiliz$ = ?is purpose4 ,! side sill is moreov] /r5g!n$ by hav+ /eel plates bolt$ to x4 ,illu/ration3 ,fig4 #fc4 ,re9=c+ ,plates4 ,! longitud9al memb]s ( ! body fram+ are t]m$ sills4 ,^! are usually ( long leaf yell[ p9e4 ,v>i\s comb9ations ( wood & /eel are employ$ = sills1 an example ( :i* is se5 9 ,figs4 #fa & #fb4 ,! sills are kept ! prop] di/ance ap>t by 8bridg+s0 or cross sills mortis$ into !m at int]vals & by 8end sills40 ,! :ole fram+ is ti$ toge!r by ! rods runn+ p>allel to ! bridg+4 ,^! tie rods are (t5 provid$ ) turn buckles = tight5+ :5 occasion may require4 ,! out] sills are t]m$ side sills2 ^? ne>e/ ! c5t] ( ! c>1 ! c5t] sills or draft timb]s2 :ile ^? betwe5 are call$ int]m$iate timb]s4 ,! rema9+ portion ( ! c> is con/ruct$ mu* aft] ! mann] ( a /eam coa*4 ,! po/s betwe5 ! w9d[s are mortis$ into ! side sill at ! bottom & into a top sill at _! upp] end4 ,!y are lat]ally brac$ by a belt rail imm$iately "u ! w9d[ op5+1 bo? ! belt rail & ! po/s be+ ga9$ out s t ! rail fits flu% ) ! po/s4 ,a wide lett] bo>d ga9$ into ! po/ j bel[ ! side plate adds to ! brac+ ( ! side ( ! c>1 z does also an iron truss usually "o-f\r? to "o-half in* ?ick & two to ?ree in*es wide :i* is ga9$ into ! po/s on ! inside runn+ j "u ! w9d[s betwe5 ! truck c5t]s1 & !n desc5ds to pass ?r\gh ! side sills & fa/5 by a bolt und]nea?4 ,! ro( consi/s ( ! upp] & l[] decks4 ,t portion ov] ! plat=m or ve/ibule is t]m$ ! hood4 ,rigidity is giv5 to ! :ole upp] portion ( ! c> by ! end plates re/+ on ! corn] po/s & ext5d+ betwe5 ! side plates at ei!r end ( ! c> body prop]1 & by /eel c>l9s :i* con=m to ! peculi> %ape ( ! ro( & ext5d betwe5 ! side plates4 ,! /eel c>l9s are usually plac$ ov] alt]nate side po/s4 ,bolt$ on ei!r side ( !m & plac$ at int]vals ( ab\t twelve in*es betwe5 are wood c>l9s4 ,! wood c>l9s ( ! l[] deck ext5d f ! side plate1 to :i* !y are fa/5$ by screws1 to ! top sill1 :i* is imm$iately bel[ ! w9d[s ( ! upp] deck4 ,above ^! w9d[s is ! top plate1 support+ ! c>l9s ( ! upp] deck1 :i* ext5d betwe5 & a few in*es beyond ! two top plates4 ,popl> %ea?+ ?ree-eigh?s or "o-half in* is nail$ ov] c>l9s & on ?is heavy canvas usually ( six or eight ounce duck is /ret*$ tightly4 ,sev]al coats ( heavy pa9t on ! canvas & a trolley bo>d = support+ ! trolley /& complete ! ro(4 ,on ! und]side ( ! c>l9s ! headl9+1 usually ( bir* or birdseye maple1 is secur$4 ,?is =ms ! int]ior f9i% ( ! ceil+ ( ! c>4 ,/eel ,c> ,fram+4 ,z a result ( ! dem&s ( ! (ficials ( ! ,new ,york ,subway = c>s ( great] /r5g? & less subject to dang] f fire1 mu* progress has be5 made 9 ! la/ few ye>s 9 ! con/ruction ( c>s ) /eel fram+4 ,/eel con/ruction is mu* m exp5sive ?an t 9 :i* ! fram+ is ( wood & is consid]ably heavi]4 ,! advantages lie p>tly 9 ! fact t x is m durable1 b ! great reason = ! int]e/ ) :i* ! new /yle ( con/ruction has be5 receiv$ is t ! dang] ( collapse & consequ5t injury to pass5g]s1 9 case ( accid5t1 is greatly dim9i%$4 ,c> ,weights4 ,! total weight ( a /reet c> ) a body #af feet long ov] corn] po/s m\nt$ on a s+le truck ) two motors is approximately #ad1jjj p\nds4 ,( ?is ! body weighs ab\t #d1ejj p\nds1 ! truck #d1djj p\nds1 & ! motors & ! electrical equipm5t ! rema9+ #e1ajj p\nds4 ,! weights ( ! sep>ate p>ts ( a c]ta9 int]urban c> measur+ #eb feet #f in*es ov] ! bump]s m\nt$ on d\ble trucks1 "o ( :i* c>ri$ two motors1 is body #cd1jfe1 motor truck #i1efe1 trail truck #f1fgj1 electrical equipm5t #ab1hjj2 total #fc1ajj4 ,an int]urban c> ( ab\t ! same size z ! "o j m5tion$ b equipp$ ) f\r motors gave ! foll[+ weights3 ,body ) controll] & resi/ance grids #ci1jjj p\nds1 trucks #ai1acj p\nds1 motors #ae1dbj p\nds2 total #gc1eej p\nds4 ,c> ,pa9t+4 ,a great deal ( att5tion is giv5 to ! prop] pa9t+ ( c>s4 ,a c> pa9t$ ) c>e & prop] mat]ials always pres5ts an attractive appe>ance1 :ile "o c>elessly pa9t$ is readily noticeable4 ,new c>s g ?r\gh an elaborate pa9t+ process4 ,! "t requir$ is f two to ?ree weeks4 ,! foll[+ s*eme may be reg>d$ z an example ( a good process3 ,a coat ( prim] is giv5 ! c> ! fir/ day4 ,on ! ?ird day all irregul>ities are putti$ up smoo?4 ,on ! f\r? & fif? days a heavy prim] is appli$1 "o coat on ea* day4 ,a coat ( fill] is giv5 on ! six? day & all[$ to h>d5 ! foll[+ day4 ,! next pa9t appli$ is t]m$ a guide coat4 ,?is is ( a color diff]5t f ! prec$+ ones & s]ves z a guide = ! rubb]s1 :o on ! foll[+ day g ov] ! c> ) m9]al wool1 f9e s&pap]1 or pumice /one1 & rub x until ! guide coat is worn away4 ,?is assures an ev5 & smoo? surface4 ,on ! t5? day ! c> is all[$ to /&4 ,a coat ( ! color desir$ is appli$1 "o on ea* ( ! foll[+ ?ree days4 ,on ! f\rte5? & fifte5? days ! c> is /rip$ ) ! desir$ ornam5ts & lett]$4 ,?is is usually done 9 alum9um or gold leaf4 ,! c> is !n giv5 ?ree coats ( v>ni% on alt]nate days1 & ! "w is complet$4 ,! be/ practice br+s ! c>s 9 once ea* ye> to be rev>ni%$4 ,illu/ration3 ,,typical ,,high ,,grade ,,track ,,con/ruction ,j4 ,g4 ,:ite ,co4 ,,electric ,,railways4 ,,"p ,,ii4 ,,ov]head ,,con/ruction4 ,illu/ration3 ,fig4 #fd4 ,trolley ,wire4 ,! trolley wire is susp5d$ f ! span wires or brackets 9 su* a way z to p]mit ( an un9t]rupt$ passage ( an upw>d press+ trolley :eel und]nea? x4 ,! trolley wire itself may be ei!r r\nd1 groov$1 or figure #h 9 section4 ,:]e a r\nd wire is us$1 ,no4 #jj ,b4 ,s4 gauge is ! mo/ common size4 ,figure #h wire1 s call$ f its section1 :i* is %[n 9 ,fig4 #fd1 is design$ to pres5t a smoo? "u surface to ! trolley :eel1 :i* w n be int]rupt$ by ! clamps or e>s us$ to support x4 ,clamps are fa/5$ to ! upp] "p ( ! figure #h4 ,! groov$ wire is roll$ ) grooves into :i* ! support+ clamps fa/54 ,?is wire also pres5ts a smoo? "u surface to ! trolley :eel4 ,illu/ration3 ,fig4 #fe4 ,trolley ,wire ,clamp & ,e>4 ,trolley-,wire ,clamps & ,e>s4 ,! trolley is support$ ei!r by clamps or by sold]$ e>s4 ,"o type ( clamp grasps ! wire by virtue ( screw pressure4 ,a sold]$ e> is %[n at ,e1 ,fig4 #fe4 ,?is e> has small projections at ea* end1 :i* are b5t ar\nd ! wire to assi/ ! sold] 9 hold+ ! wire to ! e>4 ,ano!r =m ( e>1 us$ to "s ext5t1 holds ! wire by virtue ( hav+ ! edges ( ! groove (fset or rivet$ ar\nd ! wire4 ,! e> or clamp screws to a bolt :i* is insulat$ f ! metal e> ?r\gh :i* passes ! span wire4 ,a cross-section ?r\gh a common type ( trolley-wire hang] is %[n 9 ,fig4 #ff4 ,"h !re is an out] %ell ( metal1 :i* is adapt$ to hook to ! span wire4 ,9 ?is %ell is an insulat+ bolt1 t is1 a bolt surr\nd$ ) "s =m ( insulat+ mat]ial :i* is v /rong me*anically & n likely to be crack$ by ! hamm]+ action ( ! pass+ trolley :eel4 ,mo/ ( ! insulat+ comp\nds us$ 9 mak+ trolley-wire insulators are trade secrets4 ,ano!r k9d ( insulator call$ ! 8cap & cone0 type is %[n at ,c1 ,fig4 #fe4 ,9 ^! insulators1 ! metal "p ,b :i* fa/5s to ! span wire does n completely surr\nd ! insulation ,c4 ,wood has sometimes be5 us$ = ! insulation ( trolley-wire hang]s4 ,illu/ration3 ,fig4 #ff4 ,cross-,section ,trolley ,wire ,hang]4 ,span ,wires4 ,9 city /reets1 ! trolley wire is commonly susp5d$ f span wires /ret*$ betwe5 poles locat$ on bo? sides ( ! /reet4 ,^! span wires are ( -in* or -in* galvaniz$ /r&$ /eel cable4 ,9 ord] to add to ! insulation betwe5 ! trolley wire & ! poles at ! side ( ! /reet1 :at is call$ a /ra9 insulator is plac$ 9 ! span wire4 ,?is is an insulator adapt$ to )/& ! great t5sion put ^u x by ! span wire4 ,"o ( ^! is %[n 9 ,fig4 #fg4 ,means are usually provid$ = tight5+ ! span wires z !y /ret* & z ! poles give "u ! /ra94 ,! insulator 9 ,fig4 #fg has a screw eye = t purpose4 ,illu/ration3 ,fig4 #fg4 ,/ra9 ,insulator4 ,illu/ration3 ,fig4 #fh4 ,ov]head ,con/ruction4 ,brackets4 ,9 ! bracket type ( ov]head con/ruction1 a trolley wire is fa/5$ to brackets plac$ on poles ne> ! track4 ,?is con/ruction is us$ on suburban & int]urban l9es :]e ! pres5ce ( poles ne> ! track is n objectionable4 ,x has be5 f\nd t a rigid connection ( ! trolley wire to a bracket is likely to result 9 ! break+ ( ! trolley-wire insulators4 ,= ?is reason ! brackets n[ commonly us$ provide = a flexible susp5sion ( ! trolley-wire hang] f ! bracket4 ,a bracket employ+ su* flexible con/ruction1 made by ! ,ohio ,brass ,company1 is illu/rat$ 9 ,fig4 #fh4 ,an example ( /&>d /raight-l9e bracket con/ruction is %[n 9 ,fig4 #fi4 ,fe$]s4 ,:]e additional conductivity is ne$$ beyond t furni%$ by ! trolley wire itself1 fe$]s are run on insulators along ! poles at ! side ( ! track4 ,su* fe$]s are connect$ to ! trolley wire at regul> int]vals4 ,:]e span-wire con/ruction is us$1 ! fe$ wire may be sub/itut$ = ! span wire at ! pole :]e ! connection betwe5 fe$ wire & trolley wire is made4 ,9 su* a case1 ( c\rse1 a trolley-wire hang] is us$ :i* has no insulator1 s t ! curr5t fe$s directly ?r\gh ! hang]4 ,ano!r me?od is to run ! fe$ connection p>allel ) a span wire & a %ort di/ance f x4 ,illu/ration3 ,fig4 #fi4 ,/&>d ,/raight ,l9e ,con/ruction4 ,section ,insulators4 ,section insulators are usually plac$ 9 ! trolley wire at regul> int]vals4 ,su* a section insulator is %[n 9 ,fig4 #gj4 ,its purpose is to insulate "o section ( trolley wire f ! next1 s t 9 case ! trolley wire ( "o section breaks1 or is gr\nd$ 9 any o!r mann]1 t section c be disconnect$ & ! o!r sections on ei!r side kept 9 op]ation4 ,9 l>ge city /reet-railway sy/ems1 ea* section ( trolley wire usually has its own fe$] or fe$]s1 indep5d5t ( ! o!r sections4 ,?is fe$] is suppli$ ?r\gh an automatic circuit break] at ! p[] h\se4 ,9 case a c]ta9 section ( trolley wire is gr\nd$ ! l>ge curr5t t imm$iately fl[s w op5 ! circuit break] supply+ t section2 b1 unless ! gr\nd contact is ( an extremely l[ resi/ance1 x w n affect ! op]ation ( ! o!r fe$]s4 ,%\ld x be ( suffici5tly l[ resi/ance to cause all ! g5]ator circuit break]s to op51 x w\ld1 ( c\rse1 int]rupt ! entire s]vice tempor>ily2 b usually ! circuit break] on any individual fe$] w cut t fe$] out be=e all ! circuit break]s w op54 ,illu/ration3 ,fig4 #gj4 ,section ,insulator4 ,high-,t5sion ,l9es4 ,:]e high-t5sion alt]nat+-curr5t wires are run1 z 9 ! case :]e ! road is ( su* l5g? z to require ! e/abli%m5t ( sev]al sub/ations1 ^! high-t5sion circuits are usually c>ri$ "s di/ance above ! #ejj-volt direct-curr5t trolley & fe$]s4 ,an example ( int]urban ov]head con/ruction is %[n 9 ,fig4 #fi4 ,"h ! high-t5sion wires are c>ri$ on l>ge porcela9 insulators ( a size necess>y = #bf1jjj volts4 ,^! insulators are plac$ #ce in*es ap>t4 ,high-t5sion wires are kept s f> ap>t because ( ! dang] t arcs w 9 "s way be />t$ betwe5 ! l9es1 z ! high-t5sion curr5t w ma9ta9 an extremely long arc4 ,! bl[+ ( gre5 twigs across ! l9es1 or birds ( suffici5t size fly+ into ! l9es1 is likely to e/abli% arcs :i* w tempor>ily %ort-circuit ! l9e4 ,! great] ! di/ance ap>t ( ! wires1 ! less dang] t su* ?+s w occur4 ,bo? glass & porcela9 insulators are successfully us$ on l9es ( v high t5sion4 ,glass is ! *eap] & porcela9 has ! great] me*anical /r5g?4 ,high-t5sion wires are usually ( h>d-drawn copp] or ( alum9um made up 9 ! =m ( a cable ( sev]al /r&s4 ,alum9um is light] = a giv5 conductivity ?an copp]2 &1 at ! m>ket price controll+ at ! pres5t "t1 is *eap]4 ,x is1 h[ev]1 m subject to unev5ness ( composition1 :i* leaves weak spots at c]ta9 po9ts 9 ! wire2 & t is ! reason :y alum9um is n[ always us$ 9 ! =m ( a /r&$ cable r ?an z a s+le conductor4 ,alum9um1 be+ consid]ably s(t] ?an copp] & melt+ at a l[] temp]ature1 is m likely to be worn ?r\gh z a result ( abrasions or to be melt$ (f by a tempor>y arc4 ,^! slight objections are balanc$ aga9/ its small] fir/ co/ z comp>$ ) ! co/ ( copp]4 ,! calculation ( ! prop] am\nt ( fe$ wire = a giv5 section ( road is some:at simil> to ! calculation ( electric light & p[] wir+ z already outl9$4 ,x is fir/ necess>y to e/imate approximately ! am\nt ( curr5t requir$ at diff]5t portions ( ! l9e4 ,! am\nt ( drop to be all[$ betwe5 ! p[] h\se & c>s mu/ be decid$ arbitr>ily by ! eng9e]4 ,a drop ( #aj p] c5t is probably ! "o mo/ commonly figur$ ^u 9 design+ fe$+ sy/ems4 ,! resi/ance 9 ohms ( ! copp] fe$]s requir$ to conduct a giv5 curr5t ) a giv5 loss 9 volts1 c be calculat$ by divid+ ! volts lo/ by ! curr5t1 accord+ to ,ohm's law4 ,by ! aid ( a table :i* gives ! conductivity ( v>i\s sizes ( wire accord+ to ! me?ods outl9$ 9 connection ) 8,electric ,wir+10 ! prop] numb] & size ( ! fe$]s c be det]m9$4 ,! mo/ difficult ?+ to det]m9e is ! load t w be plac$ ^u any section ( ! l9e4 ,( c\rse1 !re w be times :5 c>s are bun*$ toge!r ow+ to blockades4 ,x is out ( ! "q to provide en\gh fe$] copp] to keep ! loss 9 voltage )9 reasonable limits at su* times4 ,! ord9>y load ^u any fe$] is us$ z ! basis ( calculation 9 mo/ cases4 ,! am\nt ( curr5t requir$ p] c> dep5ds on ! weight ( ! c> & ! "* ( ! s]vice4 ,?is w be tak5 up lat] "u ! head ( 8,op]ation40 ,,?ird ,,rail4 ,illu/ration3 ,fig4 #ga4 ,?ird-,rail ,insulator4 ,location4 ,! ?ird-rail sy/em ( conduct+ curr5t to electric c>s1 z mo/ commonly employ$ 9 ! ,unit$ ,/ates1 foll[s ! example set by ! ,metropolitan ,we/ ,side ,elevat$ ,railway ( ,*icago4 ,all ! elevat$ roads 9 ! ,unit$ ,/ates are n[ op]at$ by means ( ?ird rails locat$ at "o side ( ! track4 ,! ?ird rail is an ord9>y ,t-rail & is locat$ ) ! c5t] ( its head #bj in*es outside ( ! gauge l9e ( ! ne>e/ track rail1 & #f in*es above ! top ( ! track rail4 ,on a few int]urban roads ?is di/ance has be5 increas$ 9 ord] to accommodate c]ta9 /eam railroad roll+ /ock :i* mu/ at times be op]at$ ov] ! l9e4 ,insulators4 ,! ?ird rail is support$ e fif? tie on an insulator4 ,^! insulators on fir/ con/ruction 7 made ( wood5 blocks boil$ 9 p>aff9e1 b at ! pres5t "t m sub/antial =ms ( insulation are be+ us$4 ,"o =m ( ?ird-rail insulator1 kn[n z ! 8,gonz5ba*10 has a base ( ca/ iron re/+ on ! tie4 ,ov] ?is is plac$ a cap ( insulat+ mat]ial simil> to t us$ 9 /ra9 & trolley-wire insulators4 ,ov] ?is insulat+ mat]ial is ano!r ca/-iron cap ^u :i* ! ?ird rail re/s4 ,! weight ( ! ?ird rail holds x 9 position1 & !re is no clamp+ toge!r ( ! v>i\s p>ts ( ! insulator4 ,ano!r =m ( ?ird-rail insulator is made ( :at is call$ 8recon/ruct$ granite10 & ano!r ( vitrifi$ clay4 ,fig4 #ga %[s "o ( ! latt]4 ,swit*es4 ,:]e ! ?ird rail is us$1 a contact %oe is plac$ on ea* side ( bo? trucks ( ! motor c>4 ,at swit*es x is necess>y to omit ! ?ird rail = a %ort di/ance on "o side ( ! track1 & place a %ort section ( ?ird rail on ! o!r side ( ! track s t ! curr5t supply to ! c> w be un9t]rupt$4 ,at ,highway ,cross+s4 ,:]e ! ?ird-rail sy/em is employ$ on int]urban surface l9es1 x is necess>y to omit a section ( x at e highway cross+4 ,if ! cross+ is too wide to be bridg$ across by a c>1 ! c> mu/ h suffici5t mom5tum to drift ov] su* cross+s :5 x comes to !m4 ,to connect across ! break 9 ! ?ird rail at su* po9ts1 an und]gr\nd cable is g5]ally us$4 ,?is cable mu/ be ?or\ghly protect$ aga9/ leakage ( moi/ure into ! insulation :]e x comes to ! surface = connection to ! ?ird rail4 ,ano!r =m ( ?ird rail1 laid sev]al ye>s ago on "s ( ! l9es ( ! ,new ,york1 ,new ,hav5 ,h>t=d ,railroad1 0 ( an inv]t$ ,v-%ape1 & 0 laid midway betwe5 ! track rails ) its top #a in* above !m & its bottom only #a in*es above ! ties4 ,x 0 support$ on wood5 blocks4 ,?is location ( ! ?ird rail has nev] be5 popul>1 because ( ! poor insulation ) ! rail locat$ s close to ! ties betwe5 ! rails4 ,conductivity4 ,! conductivity ( a /eel rail v>ies consid]ably4 ,a rail ( ! ord9>y composition us$ on /eam railroads is too high 9 c>bon to give ! be/ conductivity4 ,su* a rail has ab\t "o-t5? ! conductivity ( ! same cross-section ( copp]4 ,/eel c easily be obta9$1 h[ev]1 :i* w h "o-sev5? ! conductivity ( copp]1 & ! additional co/ ( obta9+ su* special /eel is q l[1 s t ! majority ( roads in/all+ ! ?ird-rail sy/em h se5 fit to pay ! extra co/ & !reby secure a s(t] rail ?an t usually employ$ 9 track rails4 ,co/4 ,! co/ ( ! ?ird-rail sy/em is less ?an an ov]head trolley sy/em1 provid$ en\gh copp] is plac$ 9 ! trolley fe$]s to make ! conductivity ( ! trolley sy/em equal to t ( ! ?ird-rail sy/em4 ,x is v seldom1 h[ev]1 t a trolley sy/em is s con/ruct$ on an int]urban road2 & h5ce ! trolley sy/em1 z usually con/ruct$1 is *eap] ?an ! ?ird-rail sy/em1 because x is n ( equal conductivity to a ?ird-rail sy/em4 ,advantages 9 ,op]ation4 ,:]e v heavy c>s or tra9s are to be op]at$1 ! ?ird-rail sy/em is decid$ly an advantage1 = two reasons4 ,9 ! fir/ place1 x af=ds ! *eap] me?od ( conduct+ a giv5 heavy volume ( curr5t2 & 9 ! second place1 ! contact %oes t conduct ! curr5t f ! ?ird rail to ! mov+ c> or tra9 are built to c>ry a mu* l>g] volume ( curr5t ?an ! trolley :eel1 :i* has only a small area ( contact on ! trolley wire4 ,ord9>ily !re are two ( ^! contact %oes 9 multiple = e motor c>4 ,ano!r advantage ( ! ?ird rail ov] ! trolley is t ! trolley may leave ! wire at high spe$s or 9 pass+ swit*es4 ,on well-con/ruct$ roads1 :]e ! trolley wire is kept 9 good alignm5t & ! track is smoo?1 !re is little tr\ble f ?is s\rce2 b x is und\bt$ly a conv5i5ce to be able to op]ate c>s or tra9s )\t giv+ any att5tion to a trolley pole4 ,illu/ration3 ,fig4 #gb4 ,cross-,section ( ,conduit4 ,,conduit ,,sy/ems4 ,! und]gr\nd conduit sy/em1 9 :i* ! conductors convey+ ! curr5t to ! c>s are locat$ 9 a conduit "u ! tracks1 is 9 use 9 two cities ( ! ,unit$ ,/ates--,new ,york ,city & ,wa%+ton1 ,d4 ,c4 ,! co/ ( ?is sy/em1 & ! dang] ( int]ruption ( ! s]vice :]e ! dra9age is n excell5t1 h prev5t$ its m ext5sive adoption4 ,! ,new ,york type ( conduit is a good example ( ?is con/ruction4 ,! conductors consi/ ( ,t-b>s 7,,cc7 ( /eel support$ f porcela9 cup insulators locat$ #ae feet ap>t 9 ! conduit4 ,a cross-section ( ! conduit is %[n 9 ,fig4 #gb4 ,at ea* insulator a h&hole is provid$ 7,fig4 #gc71 s t access may be _h to ! insulator f ! /reet surface4 ,manholes are provid$ at int]vals ( ab\t #aej feet1 s t ! dirt :i* collects 9 ! conduit c be scrap$ into ^! manholes & remov$ at int]vals4 ,! manholes also s]ve z po9ts ( dra9age to ! sew] sy/em4 ,illu/ration3 ,fig4 #gc4 ,h&hole4 ,contact ,pl[4 ,curr5t is conduct$ to ! c> ?r\gh a pair ( contact %oes commonly call$ a pl[ 7,fig4 #gd74 ,?is pl[ has ! two %oes insulat$ f ea* o!r1 & f ! frame ( ! pl[4 ,!y are provid$ ) flat spr+s t hold ! %oes aga9/ ! conduct+ b>s 9 ! conduit4 ,! %ank ( ! pl[ is ?9 en\gh 7 in*7 to ent] ! slot ( ! conduit4 ,! conductors pass up ?r\gh ! middle4 ,^! pl[s c1 ( c\rse1 be remov$ only :5 ! c> is ov] an op5 pit4 ,co/4 ,a conduit sy/em ( ?is k9d is v exp5sive to build because ( ! fact t a v deep excavation mu/ be made 9 ! /reet to accommodate ! conduit4 ,! track rails1 slot rails1 & %eet-/eel conduit l9+ are held 9 alignm5t by ca/-iron yokes plac$ #e feet ap>t4 ,! entire space ar\nd & und]nea? ^! yokes is fill$ ) concrete 9 ord] to give rigidity & a p]man5t track4 ,?ree exp5sive items1 !re=e1 ent] into ! con/ruction ( a conduit road--namely1 ! deep excavation1 :i* may call = ! *ang+ ( o!r und]gr\nd pipes or conduits 9 ! /reet2 ! l>ge am\nt ( iron & /eel ne$$ = ! yokes & slot rails2 & ! l>ge am\nt ( concrete ne$$4 ,on ,am]ican conduit roads ! slot & conduit are plac$ "u ! middle ( ! track4 ,"s ( ^! roads are simply recon/ruct$ cable-conduit roads 9 :i* ! old cable conduit has be5 us$ = electrical conductors4 ,9 ! conduit road at ,buda-,pe/1 ,hung>y1 ! slot is plac$ alongside "o ( ! track rails4 ,curr5t ,leakage4 ,! leakage on an und]gr\nd conduit road is consid]able1 because ! insulators are necess>ily locat$ 9 a damp1 dirty place1 :i* causes leakage ov] ! surface ( ! insulators4 ,?is leakage1 h[ev]1 is n prohibitive s long z ! conductor rails are n "u wat]4 ,if on acc\nt ( poor dra9age ! conductor rails become subm]g$1 ! leakage becomes s great t x is impossible to op]ate ! road4 ,illu/ration3 ,fig4 #gd4 ,contact ,pl[4 ,x w be notic$ t ! conduit sy/em z illu/rat$ "h employs two conductor rails--"o = ! positive side ( ! circuit & ! o!r = ! negative4 ,! track rails1 !re=e1 are n us$ z conductors1 & "o side ( ! circuit is n gr\nd$ z 9 ! ord9>y trolley sy/em1 al?\gh ! leakage to gr\nd may be consid]able f "o or bo? conductor rails4 ,,track ,,con/ruction4 ,gird] ,rail4 ,a great v>iety ( track rails are us$ 9 electric railways4 ,! mo/ common at "o "t 0 ! gird]1 a typical section ( :i*1 ) jo9t1 is illu/rat$ 9 ,fig4 #ge4 ,?is is an outgr[? ( ! old tram rail us$ on horse railways4 ,x has a tram alongside ( ! head1 on :i* vehicles may be driv54 ,its *ief advantage f ! /&po9t ( ! railway company is t !re is pl5ty ( room = dirt & sn[ to be pu%$ away by ! flanges ( ! c>s4 ,if ! company ma9ta9s ! pav+1 x may be to its advantage to h teams use ! /eel track r ?an ! pav+1 al?\gh ?is advantage 9 ma9t5ance is probably m ?an comp5sat$ = by ! delay ( c>s ?r\gh ! regul> use ( ! track by teams4 ,illu/ration3 ,fig4 #ge4 ,gird] ,rail4 ,trilby ,groove ,rail4 ,a modification ( ! gird] rail1 kn[n z ! ,trilby1 & sometimes z ! groov$ gird]1 is %[n 9 ,fig4 #gf4 ,a rail simil> to ?is is us$ 9 sev]al l>ge cities ( ! ,unit$ ,/ates4 ,x has a groove ( su* a %ape t ! flanges ( ! c> :eels w =ce sn[ & dirt out ( x in/ead ( pack+ x into ! bottom ( ! groove1 z 9 ! case ( ! regul> ,european n>r[-groov$ rail4 ,a n>r[-groov$ rail 9 :i* ! grooves correspond closely to ! %ape ( ! c>-:eel flanges is sure to make tr\ble 9 localities :]e !re is sn[ & ice1 z ! grooves become pack$ & d]ail ! c>s4 ,illu/ration3 ,fig4 #gf4 ,groov$ ,rail4 ,%anghai ,t-,rail4 ,9 "s sy/ems a ,t-rail is us$4 ,:]e ! ,t-rail is to be us$ ) pav+1 ! popul> =m is ! ,%anghai ,t1 %[n 9 ,fig4 #gg4 ,?is rail is high en\gh to p]mit ! use ( high pav+ blocks ar\nd x4 ,illu/ration3 ,fig4 #gg4 ,%anghai ,t-,rail & ,jo9t4 ,common ,t-,rail4 ,! ,t-rail us$ by /eam railroads is kn[n z ! ,a4 ,s4 ,c4 ,e4 /&>d ,t-rail1 because x foll[s ! /&>d dim5sions recomm5d$ = ,t-rails by ! ,am]ican ,society ( ,civil ,eng9e]s4 ,a /&>d #fe-p\nd ,t-rail ( ?is k9d is %[n 9 ,fig4 #gh4 ,o!r weights ( ?is rail h ! same relative proportions4 ,su* a rail is us$ = int]urban roads1 & = suburban l9es 9 /reets :]e !re is no block pav+4 ,! high rails are us$ to facilitate pav+ ) high pav+ blocks4 ,illu/ration3 ,fig4 #gh4 ,/&>d ,a4 ,s4 ,c4 ,e4 ,rail & ,"o ,jo9t ,plate4 ,track ,support4 ,! great] portion ( track is laid on wood5 ties4 ,^! ties1 9 ! mo/ sub/antial wood5 tie con/ruction1 are #f in*es by #h in*es 9 section1 & #h feet long4 ,!y are spac$ two feet betwe5 c5t]s4 ,sometimes small] ties1 spac$ f>!r ap>t1 are us$ 9 *eap] =ms ( con/ruction2 b ! =ego+ figures are ^? ( ! be/ con/ruction kn[n 9 ,am]ican railway practice4 ,9 pav$ /reets1 ties are usually employ$1 al?\gh sometimes :at is kn[n z 8concrete /r+]0 con/ruction is us$ in/ead ( ties to support ! rails4 ,a /rip ( concrete ab\t #ab in*es deep is laid "u ea* rail1 & ! rails are held to gauge by ties or tie rods plac$ at frequ5t int]vals4 ,sometimes ! concrete is made a cont9u\s b$ "u ! entire track4 ,9 mo/ l>ge cities ! concrete f\ndation is us$ "u all pav+2 & consequ5tly1 :5 concrete is us$ in/ead ( ties to support ! rails1 ?is concrete is simply a cont9uation ( ! pav+ f\ndation4 ,:]e ties are us$1 !y are laid sometimes 9 gravel1 cru%$ /one1 or s&1 al?\gh frequ5tly1 9 ! l>ge/ cities1 !y are emb$d$ 9 concrete4 ,sometimes ?is concrete is ext5d$ "u ! ties1 & sometimes x is simply put ar\nd ! ties4 ,balla/4 ,a balla/ ( gravel1 brok5 /one1 c9d]s1 or o!r mat]ial :i* is self dra9+ & :i* w pack to =m a solid b$ "u ! ties1 %\ld be us$ to get ! be/ results "u all =ms ( tie con/ruction1 :e!r 9 pav$ /reets or on a private "r ( way1 z on an int]urban road4 ,( c\rse1 if concrete is plac$ "u ! ties1 ! gravel or rock balla/ is n necess>y4 ,if ties are plac$ directly 9 s(t e>?1 :i* =ms mud :5 wet1 !y w "w up & d[n "u ! weight ( pass+ tra9s1 & an insecure f\ndation = ! track w be ! result4 ,jo9ts4 ,! matt] ( secur+ a prop] jo9t = fa/5+ toge!r ! ends ( rails s z to make a smoo? rid+ track )\t appreciable j> or jolt :5 ! :eels pass a jo9t1 has be5 giv5 mu* /udy by electric railway eng9e]s4 ,a section ?r\gh an ord9>y bolt$ angle-b> jo9t is %[n 9 ,fig4 #ge4 ,?is jo9t is =m$ by bolt+ a c\ple ( b>s1 "o on ea* side ( ! rails4 ,! edges ( ^! b>s are made accurately to su* an angle t !y w w$ge 9 betwe5 ! head & base ( ! rail z ! bolts are tight5$2 h5ce ! "n angle b>s4 ,?is is ! =m ( jo9t g5]ally us$ on /eam railroads & on electric roads 9 expos$ track1 or 9 track :]e ! jo9ts are easily accessible1 z 9 dirt /reets4 ,9 pav$ /reets1 ! undesirability ( te>+ up ! pavem5t frequ5tly to tight5 ! bolts on su* jo9ts1 has l$ to ! inv5tion ( sev]al o!r types1 :i* w be describ$ lat]4 ,nev]!less v good results h be5 obta9$ 9 rec5t ye>s ) bolt$ jo9ts laid 9 pav$ /reets :]e c>e has be5 giv5 to details 9 lay+ ! track1 & :]e ! jo9ts h be5 tight5$ sev]al times be=e ! pav+ is f9ally laid ar\nd !m4 ,weld$ ,jo9ts4 ,sev]al =ms ( weld$ jo9ts are 9 use4 ,all ^! weld$ jo9ts fa/5 ! ends ( ! rails toge!r s t ! rail is practically cont9u\s--j z if !re 7 no jo9ts--s f> z ! runn+ surface ( ! rail is conc]n$4 ,x 0 ?\ght at "o "t t a cont9u\s rail w\ld be an impossibility because ( ! contraction & expansion ( ! rail "u heat & cold1 :i*1 x 0 ?\ght1 w\ld t5d to pull ! rails ap>t 9 cold wea!r & to cause !m to b5d & buckle out ( l9e 9 hot wea!r4 ,exp]i5ce has conclusively %[n1 h[ev]1 t contraction & expansion are n to be fe>$ :5 ! track is laid 9 a /reet :]e x is cov]$ ) pav+ mat]ial or dirt4 ,! pav+ t5ds to hold ! track 9 l9e1 & to protect x f extremes ( heat & cold4 ,! reason t contraction & expansion d n "w havoc on track ) weld$ jo9ts1 is probably t ! rails h en\gh ela/icity to provide = ! contraction & expansion )\t break+4 ,x is f\nd t ! be/ results are secur$ by weld+ rail jo9ts dur+ cool wea!r1 s t ! effect ( contraction 9 ! colde/ wea!r w be m9imum4 ,9 ?is case1 ( c\rse1 !re w be consid]able expansion ( ! track 9 ! hotte/ wea!r1 b ?is does n cause s]i\s b5d+ ( ! rails2 :]eas occasionally1 if ! track is weld$ 9 v hot wea!r1 ! contraction 9 w9t] w cause ! jo9t to break4 ,illu/ration3 ,,portable ,,cupola ,,= ,,ca/-,,weld+ ,,jo9ts ,,( ,,/reet ,,c> ,,rails4 ,ca/-,weld$ ,jo9ts4 ,! process ( ca/-weld+ jo9ts consi/s 9 p\r+ v hot ca/ iron into a m\ld plac$ ar\nd ! ends ( ! rails4 ,^! m\lds are ( iron2 & to prev5t _! /ick+ to ! jo9t :5 x is ca/1 !y are pa9t$ inside ) a mixture ( l9se$ oil & graphite4 ,iron is usually p\r$ s hot t1 be=e x cools1 ! base ( ! rail 9 ! c5t] ( ! molt5 jo9t becomes p>tially melt$1 ?us caus+ a true union ( ! /eel rail & ca/-iron jo9t4 ,?is makes ! jo9t solid me*anically & a good electrical conductor4 ,to supply melt$ ca/ iron dur+ ! process ( ca/-weld+ jo9ts on ! /reet1 a small portable cupola on :eels is employ$4 ,fig4 #gi gives an idea ( ! process ( mak+ ca/-weld$ jo9ts4 ,illu/ration3 ,fig4 #gi4 ,process ( ,ca/-,weld+ ,jo9t4 ,electrically ,weld$ ,jo9ts4 ,an electrically weld$ jo9t is made by weld+ /eel blocks to ! rail ends4 ,a /eel block is plac$ on ea* side ( ! jo9t1 & curr5t ( v l>ge volume is pass$ ?r\gh f "o block to ! o!r4 ,?is curr5t is s l>ge t ! electrical resi/ance betwe5 ! rail & /eel block causes t po9t to become molt54 ,curr5t is !n %ut (f1 & ! jo9t all[$ to cool4 ,!re is 9 ?is case a true weld betwe5 ! /eel blocks & ! rails & jo9t4 ,an electric weld+ outfit be+ exp5sive to ma9ta9 & op]ate1 ?is process is us$ only :]e a l>ge am\nt ( weld+ c be done at once4 ,curr5t is tak5 f ! trolley wire4 ,a rot>y conv]t] set takes #ejj-volt direct curr5t f ! trolley wire1 & conv]ts x into alt]nat+ curr5t4 ,?is alt]nat+ curr5t is tak5 to a /atic trans=m] :i* r$uces ! voltage & gives a curr5t ( great quantity at l[ voltage1 ! latt] curr5t be+ pass$ ?r\gh ! blocks & rails 9 ! weld+ process4 ,a massive pair ( clamps is us$ to hold ! blocks aga9/ ! rails1 & to conduct ! curr5t to & f ! jo9t :ile x is be+ weld$4 ,^! clamps are wat]-cool$ by hav+ wat] circulat$ ?r\gh !m s t !y w n become ov]heat$ at ! po9t ( contact ) ! /eel blocks4 ,!rmit ,weld+4 ,a process ( weld+ rail jo9ts :i* 0 develop$ aft] ! ca/-weld+ & electric-weld+ processes1 is kn[n z ! ,golds*midt process1 :i* makes use ( a mat]ial call$ 8!rmit0 = supply+ heat to make ! weld4 ,a m\ld is plac$ ar\nd ! jo9t & ! !rmit is put 9 ?is m\ld & ignit$4 ,! heat produc$ by ! !rmit is s int5se z to r$uce ! iron 9 ! !rmit mixture & make a weld$ jo9t4 ,! !rmit consi/s ( a mixture ( f9ely p[d]$ alum9um & iron oxide4 ,:5 ?is is ignit$1 ! alum9um oxidizes1 t is1 absorbs oxyg5 s rapidly t an int5se heat is ! result4 ,9 ! process ( oxidation1 ! alum9um takes ! oxyg5 f ! oxide ( iron1 leav+ molt5 metallic iron1 :i* metallic iron makes ! weld by union ) ! molt5 rail ends4 ,?is process has ! advantage ov] o!r weld+ processes1 ( n requir+ an elaborate app>atus & a l>ge crew ( m5 to op]ate x2 & consequ5tly x c be us$ :]e b a few jo9ts are to be weld$4 ,illu/ration3 ,fig4 #hj4 ,*annel ,p9 ,bond4 ,bond+ & ,return ,circuits4 ,:5 ! track rails are us$ z ! conductors1 z is usually ! case1 x is necess>y to see t ! electrical conductivity ( ! rail jo9ts does n (f] too high a resi/ance to ! passage ( ! curr5t4 ,= ?is reason1 :5 bolt$ or angle-b> jo9ts are us$1 ! rails are bond$ toge!r by means ( copp] bonds4 ,x 0 soon f\nd aft] electric roads 7 9 use a %ort "t1 t unless ! rail ends 7 s bond$1 ! resi/ance ( ! jo9ts 0 s great z to cause great loss ( p[] 9 ! track4 ,fir/1 small iron bonds 7 us$2 b ^! bonds 7 s insuffici5t t l>ge copp]-wire bonds soon began to be us$2 & at ! pres5t "t1 on l>ge roads1 bonds ( heavy copp] cable are common4 ,! resi/ance ( a /eel rail1 su* z us$ 9 city /reets1 is ab\t elev5 times t ( copp]4 ,9 ord] to secure z great c>ry+ capacity at ! rail jo9t z is af=d$ by ! unbrok5 rail1 x is !re=e necess>y to in/all bonds hav+ a total cross-section t ( ! rail4 ,:]e weld$ jo9ts are us$1 bond+ is unnecess>y1 except at cross+s & swit*es :]e bolt$ jo9ts are employ$4 ,:]e track is weld$1 h[ev]1 cross bonds %\ld be put 9 at frequ5t int]vals f "o rail to ano!r1 &1 if ! track is d\ble1 f "o track to ! o!r1 s t if "o ( ! track rails breaks at a jo9t !re w be a pa? ar\nd ! break = ! curr5t4 ,illu/ration3 ,fig4 #ha4 ,*icago ,rail ,bond4 ,illu/ration3 ,fig4 #hb4 ,rail ,bond4 ,a great _m s*emes h be5 devis$ to insure good contact betwe5 ! copp] bond & ! rail1 z ! t]m9al is ! weak po9t 9 any bond4 ,"o ( ! e>lie/ & mo/ effici5t ( small bonds 0 made by ! use ( *annel p9s1 ,fig4 #hj4 ,?is bond consi/$ ( a piece ( copp] wire hav+ its ends plac$ 9 ! holes 9 ! rail ends4 ,alongside ?is wire1 a *annel p9 0 driv5 94 ,! objection to ! *annel p9 0 ! small area ( contact betwe5 ! copp] bond & rail4 ,next aft] ! *annel p9 came ! ,*icago type ( bond1 ,fig4 #ha1 :i* is a piece ( heavy copp] wire ) ?imbles =g$ on ! ends4 ,^! ?imbles 7 plac$ 9 accurately fitt$ holes 9 ! rail ends1 & a w$ge-%ap$ /eel p9 0 driv5 into ! ?imbles to exp& !m tightly into ! hole 9 ! rail4 ,sev]al o!r bonds us+ modifications ( ?is pr9ciple are 9 use4 ,a type ( bond 9 v common use consi/s ( solid copp] rivet-%ap$ t]m9als1 ,fig4 #hb4 ,betwe5 ^! t]m9als is a piece ( flexible /r&$ copp] cable1 made flat to g "u ! angle b>s4 ,9 "o type ! t]m9al lugs are ca/ ar\nd ! ends ( ! cables1 & 9 ano!r type ! cables are =g$ at _! ends into solid rivet-l t]m9als4 ,^! t]m9al rivets 7 fir/ appli$ z any o!r rivets1 ) ! use ( a rivet+ hamm]4 ,because ( ! difficulty ( ?or\ghly exp&+ su* l>ge rivets into ! holes made = !m 9 ! rails1 x has become cu/om>y to compress ^! rivets ei!r ) a screw press or a portable hydraulic press1 :i* br+s su* great pressure to be> on ! opposite ends ( ! rivet t x is =c$ to exp& itself s z to fill ! hole 9 ! rail completely4 ,?is expansion is made possible by ! ductile "* ( ! copp]4 ,?is great ductility *>act]i/ic ( copp]1 h[ev]1 has be5 ! s\rce ( "o ( ! difficulties 9 connection ) rail bond+1 because ! s(t copp] t]m9al has a t5d5cy to "w loose 9 ! hole made = x 9 ! rail4 ,x is practically impossible to ma9ta9 good bond+ :]e ! rail jo9ts are s loose z to all[ consid]able motion betwe5 ! rail ends4 ,sev]al types ( bonds h be5 introduc$1 9 :i* ! contact betwe5 ! rail & bond is made by an extra piece or ?imble4 ,ano!r me?od ( exp&+ bond t]m9als into ! holes made to receive !m1 is t employ$ 9 ! ,g5]al ,electric ,company's bond4 ,9 x a s(t p9 9 ! c5t] ( ! t]m9al is exp&$ by compression ( ! t]m9al s t x =ces ! copp] surr\nd+ x outw>d4 ,! copp] t]m9al1 9 exp&+ to fill ! hole1 is !re=e back$ by ! /eel c5t] p94 ,all types ( bonds mu/ be in/all$ ) great c>e if !y are to be effici5t4 ,unless ! bond t]m9al ?or\ghly fills ! hole & is tightly exp&$ into x1 moi/ure w creep into ! space betwe5 ! copp] & ! iron1 & ! copp] w become coat$ ) a non-conduct+ scale :i* de/roys ! conductivity ( ! contact4 ,! pla/ic rail bond1 s call$ because x dep5ds = ! contact betwe5 ! rail & ! bond ^u a pla/ic1 putty-l alloy ( m]cury & "s o!r metal1 is appli$ 9 a numb] ( diff]5t ways4 ,"o =m consi/s ( a /rip ( copp] held by a spr+ aga9/ ! rail ends "u ! fi%-plate4 ,! rail ends at ! po9t ( contact ) ?is /rip ( copp] are amalgamat$ & made bright by ! use ( a m]cury comp\nd simil> to ! pla/ic alloy4 ,^! po9ts ( contact are !n daub$ ) pla/ic alloy1 & ! copp] bond plate appli$4 ,x is n necess>y1 ) any =m ( pla/ic bond1 t ! me*anical contact be unyield+1 z ! amalgamat$ surfaces ) ! aid ( ! pla/ic alloy betwe5 !m1 ma9ta9 a good conductivity 9 spite ( any slight motion4 ,! pla/ic alloy c be appli$ 9 a numb] ( o!r ways1 "o ( :i* is to drill a hole =m+ a small cup 9 ! rail base 9 adjac5t rail ends1 fill ^! cups ) pla/ic alloy1 & bridge ! space betwe5 !m ) a %ort copp] bond hav+ its ends project+ d[n into ! cups4 ,resi/ance ( ! ,track4 ,! resi/ance ( ! return circuit is usually mu* high] ?an x %\ld be ow+ to ! bad contact ( ! bonds4 ,! resi/ance ( rails v>ies greatly ) ! proportions ( c>bon1 manganese & phosphorus4 ,! foll[+ figures1 h[ev]1 may be reg>d$ z ! av]age4 ,weight p] ,y>d4 ,resi/ance ,s+le ,rail p] ,mile4 #ej 4#jbec ohms #fj 4#jbaa 0 #gj 4#jahj 0 #hj 4#jaei 0 #ij 4#jad 0 ,a track laid ) cont9u\s rails z 9 ! case ( weld$ jo9ts1 w\ld h "o-half ! resi/ance giv5 s9ce !re are two rails to be consid]$4 ,te/s ( new unbond$ track con/ruct$ ) rails #fj feet long %[ t ! jo9ts cause an increase ( 4#be ohms or m p] mile4 ,sev]al roads 9 te/+ bonds consid] a bond good :5 ! bond & "o foot ( ! rail ov] x h a resi/ance equal to five feet ( ! solid rail4 ,supplem5t>y ,return ,fe$]s4 ,on "s l>ge roads x is necess>y to run additional return fe$]s f ! p[] h\se to v>i\s po9ts on ! sy/em1 to supplem5t ! conductivity ( ! rails4 ,o!rwise ! track rails ne> ! p[] h\se w\ld h to c>ry all ! curr5t1 & 9 "s cases !re are n en\gh su* l9es ( track pass+ ! p[] h\se to d ?is prop]ly4 ,sometimes ^! fe$]s are laid und]gr\nd 9 tr\ghs2 sometimes !y are laid b>e 9 ! gr\nd1 & sometimes on ov]head pole l9es4 ,:5 laid 9 ! gr\nd1 frequ5tly old rails are us$ in/ead ( copp] or alum9um cables4 ,! old rails are1 ( c\rse1 ?or\ghly bond$ toge!r ) bonds giv+ a conductivity ne>ly equal to t ( ! unbrok5 rail4 ,,fe$] ,,sy/ems4 ,illu/ration3 ,fig4 #hc4 ,!re are two g5]al s*emes ( direct curr5t fe$+ 9 common use4 ,"o ( ^! is %[n 9 ,fig4 #hc4 ,"h ! trolley wire is cont9u\s & is f$ into at diff]5t po9ts4 ,! long fe$]s supply+ ! m di/ant portion ( ! road are l>g] ?an ^? supply+ ! trolley ne> by1 s z to ma9ta9 z ne>ly z is feasible ! same pot5tial ! entire l5g? ( ! l9e4 ,) su* a sy/em ( fe$+1 9 ord] to ma9ta9 absolutely ! same voltage at all po9ts1 x w\ld be necess>y to h j "o trolley fe$] & t fe$+ into ! extreme end ( ! l9e f>!/ f ! p[] /ation & fur!r to make ! resi/ance p] #a1jjj ft4 ( trolley & fe$] ! same z ! resi/ance p] #a1jjj ft4 ( ! track return circuit4 ,! plan %[n 9 ,fig4 #hc evid5tly does n fully c>ry out ^! r impracticable requirem5ts b is 9 ! nature ( a compromise1 giv+ a high] pot5tial ne> ! p[] /ation ?an at di/ant po9ts b nev]!less mu* m ev5 pot5tial ?an if ! heavie/ fe$]s 7 fe$+ into ! trolley ne> ! p[] h\se4 ,! o!r plan1 %[n 9 ,fig4 #hd1 divides ! trolley wire into sections & fe$s ea* section ?r\gh a sep>ate fe$] :i* is calculat$ ( su* size z to ma9ta9 ! same voltage on all ! sections ) ! ord9>y load4 ,9 calculat+ a fe$] sy/em a c]ta9 probable load is assum$ at c]ta9 po9ts along ! l9e4 ,?is load w manife/ly dep5d on ! size & numb] ( c>s 9 op]ation1 grades & _m local conditions4 ,illu/ration3 ,fig4 #hd4 ,drop 9 rail section #c4a ,volts #b4a ,volts #a4je ,volts ,total drop 9 rail #c4a 0 #e4b 0 #f4be 0 ,drop 9 trolley #bj4e 0 #bj4e 0 #bj4e 0 ,drop 9 fe$] #cf4d 0 #cd4c 0 #cc4be 0 ,resi/ance fe$] 4#gbh ,ohms 4#fhf ,ohms 4#ffe ,ohms ,feet p] ohm #gbec #bcjjj #cigjj ,size ( wire ,no4 #a #bej1jjj ,c4 ,m4 #dbj1jjj ,c4 ,m4 ,! foll[+ example w %[ ! me?od pursu$4 ,! figures result+ f ! calculations are plac$ imm$iately bel[ ! sections to :i* !y ref] 9 ,fig4 #hd4 ,! rails are assum$ to be #gj p\nd to ! y>d4 ,^! h a resi/ance ( ab\t 4#jah ohms p] mile4 ,add+ "o-six? = additional resi/ance ( bonds gives 4#jba & s9ce ! track is compos$ ( two rails ! resi/ance ( ! track w be "o-half ( ?is or 4#jaje ohms p] mile4 ,! maximum drop 9 any section occurs :5 ! c> is f>!/ f ! p[] h\se4 ,ea* c> is assum$ to take #ej amp]es & ! fe$]s are to be s design$ z to all[ a #aj p] c5t or #fj volts drop4 ,! curr5t 9 ! two miles ( track ne>e/ ! p[] h\se is #aej amp]es1 9 ! next section #ajj amp]es1 & 9 ! la/ section #ej amp]es4 ,! drop 9 ea* section is z %[n4 ,! drop 9 ! trolley :i* is #jj wire is1 9 ea* section1 #bj4e volts4 ,subtract+ f #fj volts ! drop 9 ! return circuit & trolley1 gives ! all[able drop 9 ! fe$]4 ,! resi/ance ( ea* fe$] c be calculat$1 s9ce ! curr5t 9 ea* "o is #ej amp]es4 ,! fir/ fe$] is "o mile long1 ! second #c miles & ! ?ird #e miles1 & ) ^! figures ! feet p] ohm c be comput$4 ,! size ( wire may be obta9$ by ref]5ce to a table ( copp] wire resi/ances4 ,,block ,,signals ,,= ,,electric ,,railways4 ,! simple/ block signal us$ by electric roads is a h&-op]at$ "o con/ruct$ on ! pr9ciple %[n 9 ! diagram ,fig4 #he4 ,a d\ble ?r[ swit* is plac$ at ea* t]m9al ( ! section ( track t is to be protect$4 ,illu/ration3 ,fig4 #he4 ,! swit*es h no c5tral position1 ! knife blade always mak+ contact ) "o or ! o!r ( ! t]m9als %[n4 ,if ! lamps are light$1 ?r[+ ei!r "o ( ! swit*es w put !m out4 ,if !y are n burn+1 !y w be light$ by ?r[+ ei!r "o ( ! swit*es4 ,a motorman on rea*+ a section ( track f9d+ ! lamps n burn+ ?r[s ! swit*4 ,lamps n[ burn 9 ea* swit* box & %[ t ! section is 9 use4 ,on arriv+ at ! o!r t]m9al ( ! block ! swit* is ?r[n1 ext+ui%+ ! lights & %[+ t ! block is cle>4 ,automatic signal sy/ems h be5 devis$ on ! same pr9ciple1 9 :i* magnets1 op]at$ by contacts made by ! passage ( ! trolley :eel1 cause ! lamps to be light$ & ext+ui%$ automatically4 ,,electrolysis4 ,mu* has be5 said ab\t ! possibilities ( electrolysis ( und]gr\nd metal by ! action ( ! return curr5t ( electric railways1 :5 su* railways are op]at$ ) gr\nd$ circuits1 z !y usually are4 ,if electric curr5t is pass$ ?r\gh a liquid f "o metal electrode to ano!r1 electrolysis w take place2 t is1 metal w be deposit$ on ! negative pole1 & ! positive pole or electrode w be dissolv$ by becom+ oxidiz$ f ! action ( ! oxyg5 collect+ at t pole4 ,illu/ration3 ,fig4 #hf4 ,%[+ ,electrolytic ,action4 ,9 an electric-railway return circuit1 !re is necess>ily a diff]5ce ( pot5tial betwe5 ! rails at outly+ p>ts ( ! sy/em & ! rails & o!r buri$ pieces ( metal locat$ ne> ! p[] h\se4 ,j :at ?is total diff]5ce ( pot5tial is1 dep5ds on ! loss ( voltage 9 ! return circuit4 ,?us1 suppose !re is #be volts drop 9 ! return circuit betwe5 a c]ta9 po9t on ! sy/em & ! p[] /ation4 ,!re is1 !re=e1 a pressure ( #be volts t5d+ to =ce ! curr5t ?r\gh ! moi/ e>? f ! rails at di/ant portions ( ! l9e1 to ! rails1 wat] pipes1 & o!r connect$ metallic /ructures locat$ 9 ! e>? ne> ! p[] /ation4 ,! am\nt ( curr5t t w ?us fl[ to e>? 9 pref]5ce to rema9+ 9 ! rails1 dep5ds on ! relative resi/ance ( ! rails1 ! e>?1 & ! o!r pa?s (f]$ to ! curr5t to return to ! p[] h\se4 ,to take a v simple case1 let u suppose a s+le-track road1 ,fig4 #hf1 ) a p[] h\se at "o end1 & a p>allel l9e ( wat] pipe on ! same /reet pass+ ! p[] h\se4 ,if ! positive t]m9als ( ! g5]ators are connect$ to ! trolley wire1 ! curr5t passes1 z indicat$ by ! arr[s1 out ov] ! trolley wire ?r\gh ! c>s & to ! rails4 ,:5 x has rea*$ ! rails x has ! *oice ( two pa?s back to ! p[] h\se4 ,"o is ?r\gh ! rails & bond+2 ! o!r is ?r\gh ! moi/ e>? to ! l9e ( wat] pipe & back to ! p[] h\se1 leav+ ! pipe = ! rails1 at ! p[] h\se4 ,%\ld ! bond+ ( ! rails be v defective1 consid]able curr5t might pass ?r\gh ! e>? to ! wat] pipe4 ,rememb]+ n[ ! pr9ciples ( electrolysis1 we see t ! oxidiz+ action ( ?is fl[ ( curr5t f ! rails to ! wat] pipes at ! di/ant portion ( ! road w t5d to de/roy ! rails1 b w n h>m ! wat] pipe at t po9t1 z x w t5d to deposit metal ^u x4 ,:51 h[ev]1 ! curr5t arrives at ! p[] h\se1 x mu/ 9 "s way leave ?is wat] pipe to get back to ! rails1 & s to ! negative t]m9als ( ! g5]ators4 ,"h we see t !re is a *ance = electrolysis ( ! wat] pipe1 because at ?is po9t ! wat] pipe =ms ! positive electrode1 :i* is ! "o likely to be oxidiz$ & de/roy$4 ,?is v simple case is tak5 m]ely = illu/ration4 ,9 actual practice ! conditions are nev] s simple z ?is1 = !re are v>i\s pipes locat$ 9 ! gr\nd runn+ 9 v>i\s directions1 :i* complicate ! case v mu*2 b we c see f ?is simple example t ! pr9cipal place electrolysis ( wat] pipe is to be fe>$ is at po9ts :]e a l>ge volume ( curr5t is leav+ ! wat] pipe to take to "s o!r conductor4 ,z an indication ( h[ mu* curr5t is likely to be leav+ ! wat] pipes at v>i\s po9ts1 x is cu/om>y to measure ! voltage betwe5 ! wat] pipes & ! electric railway track & rails4 ,:5 ?is voltage is high1 x does n necess>ily mean t a l>ge volume ( curr5t is leav+ ! wat] pipes at ! po9t :]e ^! pipes are sev]al volts positive ) ref]5ce to ! rails2 b su* voltage read+s indicate t1 if !re is a pa? ( suffici5tly l[ resi/ance ?r\gh ! e>?1 & if ! moi/ure 9 ! e>? is suffici5tly impregnat$ ) salts or acids1 !re w be tr\ble f an electrolytic action due to a l>ge fl[ ( curr5t4 ,!re is obvi\sly no me?od ( measur+ exactly ! am\nt ( curr5t leav+ a wat] pipe at any giv5 po9t1 s9ce ! pipe is buri$ 9 ! e>?4 ,voltmet] read+s betwe5 pipes & rails simply s]ve to give an indication z to :]e !re is likely to be tr\ble f electrolysis4 ,! dang] to und]gr\nd pipes & o!r metallic /ructures f electrolysis has be5 mu* ov]e/imat$ by "s p1 z ! tr\ble c be ov]come by prop] c>e & att5tion to ! return circuit4 ,tr\ble f electrolysis1 h[ev]1 is sure to occur unless su* c>e is giv54 ,prev5tion ( ,electrolysis4 ,rem$ies = electrolysis may be classifi$ "u two heads--g5]al & specific4 ,! g5]al rem$y is obvi\sly to make ! resi/ance ( ! circuit ?r\gh ! rails & supplem5t>y return fe$]s s l[ t !re w be b little t5d5cy = ! curr5t to seek o!r conductors1 su* z wat] & gas pipes & ! lead cov]+ ( und]gr\nd cables4 ,?is rem$y consi/s 9 heavy bond+1 9 ample connections1 ar\nd swit*es & special "w :]e ! bond+ is especially liable to injury1 & 9 additional return conductors at po9ts ne> ! p[] h\se to supplem5t ! conductivity ( ! rails4 ,x is important t all rail bonds be te/$ at int]vals ( six mon?s to "o ye> 9 ord] t defective bonds may be locat$ & r5ew$1 z a few defective bonds c greatly l[] ! effici5cy ( an o!rwise l[-resi/ance circuit4 ,! specific rem$y = electrolysis :i* may be appli$ to r$uce electrolytic action at c]ta9 specific po9ts1 consi/s 9 connect+ ! wat] pipe at ! po9t :]e electrolysis is tak+ place1 ) ! rail or o!r conductor to :i* ! curr5t is fl[+4 ,?us1 = example1 if x is f\nd t a l>ge am\nt ( curr5t is leav+ a wat] pipe & fl[+ to ! rails or to ! negative return fe$]s at ! p[] h\se1 ! electrolytic action at ?is po9t c obvi\sly be /opp$ by connect+ ! wat] pipe ) ! rails by means ( a l[-resi/ance copp] wire or cable1 !reby %ort-circuit+ ! po9ts betwe5 :i* electrolytic action is tak+ place4 ,!re are c]ta9 cases 9 :i* x is advisable to adopt su* a specific rem$y4 ,x %\ld be rememb]$1 h[ev]1 t a l[-resi/ance connection ( ?is k9d1 :ile x r$uces electrolysis at po9ts ne> ! p[] h\se1 is an add$ inducem5t to ! curr5t to take to ! wat] pipes at po9ts di/ant f ! p[] h\se1 because ( ! decrease 9 resi/ance ( ! wat]-pipe pa? to ! p[] h\se result+ f ! introduction ( ! connection betwe5 ! wat] pipe & ! negative return fe$] at ! p[] h\se4 ,) ! wat] pipes connect$ to ! return fe$]s 9 ! vic9ity ( ! p[] h\se1 ! curr5t :i* fl[s f ! rails to ! wat] pipes at po9ts di/ant f ! p[] h\se w obvi\sly cause electrolysis ( ! rails b n ( ! wat] pipes1 s9ce ! curr5t is pass+ f ! e>? to ! pipe1 & ! pipe is negative to ! e>?4 ,9 ?is case ! pr9cipal dang] is t ! high resi/ance ( ! jo9ts betwe5 ! l5g?s ( wat] pipe w cause curr5t to fl[ ?r\gh ! e>? ar\nd ea* jo9t1 z indicat$ on "s ( ! jo9ts1 ,fig4 #hf1 & w cause electrolytic action at ea* jo9t4 ,x is evid5t1 h[ev]1 t ! conditions ( ! track circuit & bond+ mu/ be v bad if curr5t w\ld fl[ ov] a l9e ( wat] pipe1 ) its high-resi/ance jo9ts1 9 suffici5t volume to cause electrolysis1 9 pref]5ce to ! rail-return circuit1 especially s9ce ord9>ily ! resi/ance (f]$ to ! fl[ ( curr5t ov] ! wat] pipes back to ! p[] h\se mu/ include ! resi/ance ( ! e>? betwe5 ! tracks & wat] pipes4 ,x is usually consid]$ inadvisable to connect tracks & wat] pipes at po9ts di/ant f ! p[] h\se1 because ( ! dang] ( electrolysis at wat]-pipe jo9ts1 z j expla9$4 ,me?ods ( te/+ rail bonds 9 ! track w be expla9$ "u ! head ( 8,te/s40 ,,p[] ,,supply ,,& ,,di/ribution4 ,direct-,curr5t ,fe$+4 ,z already expla9$1 ! majority ( electric railways are op]at$ on a #ejj-volt con/ant-pot5tial direct-curr5t sy/em ) a gr\nd return4 ,a con/ant pot5tial ( #dej to #eej volts is ma9ta9$ betwe5 ! trolley wire & track4 ,:]e ! trolley wire is n suffici5t1 additional fe$]s are run f ! p[] h\se & connect$ to ! trolley wire1 ! numb] ( fe$]s dep5d+ on ! di/ance f ! p[] h\se & ! traffic4 ,boo/] ,fe$+4 ,boo/]s are sometimes us$ on long fe$] l9es :]e !re is a heavy load only a small portion ( ! "t4 ,^! boo/]s are direct-curr5t dynamos t are connect$ 9 s]ies ) ! fe$] ^u :i* ! voltage is to be rais$ above ! regul> p[]-h\se voltage4 ,! boo/] may be driv5 ei!r by a small /eam eng9e or by an electric motor4 ,! simple/ =m ( boo/] is a s]ies-w\nd dynamo4 ,a boo/] armature mu/1 ( c\rse1 be ( suffici5t curr5t capacity to pass all ! curr5t t w be requir$ on its fe$]4 ,! voltage yield$ by ?is dynamo1 plus ! p[]-/ation voltage1 is ! voltage ( ! boo/$ fe$] z x leaves ! p[] h\se4 ,suppos+ t a s]ies-w\nd boo/] w give #abe volts at full load2 x is obvi\s t be+ s]ies-w\nd x w give no voltage at no load4 ,! voltage w increase approximately z ! load on ! fe$] increases2 & s9ce ! drop 9 voltage on ! fe$] = :i* ! boo/] is to comp5sate also v>ies ) ! load1 ! action ( ! boo/] is simply to add suffici5t voltage to its fe$] at any in/ant to comp5sate = ! l9e loss ^u t fe$] & to ma9ta9 approximately con/ant pot5tial at ! f> end ( ! fe$]4 ,boo/]s rais+ ! p[]-/ation voltage ( a fe$] m ?an #bej volts above ! normal p[]-/ation voltage1 are n common1 ?\gh cases are on record :]e a fe$] has be5 boo/$ z high z #a1ajj volts above ! p[]-/ation voltage4 ,s9ce all ! p[] us$ 9 driv+ a boo/] is wa/$ 9 l9e loss1 ?is me?od ( fe$+ is n economical2 b :]e us$ only a few days out ( ! ye> x is sometimes to be pref]r$ to a heavy inve/m5t 9 fe$]s4 ,! inve/m5t 9 fe$]s might involve m int]e/ *>ges ?an ! co/ ( p[] wa/$ 9 boo/] fe$+ w\ld am\nt to4 ,alt]nat+-,curr5t ,transmission4 ,high-t5sion alt]nat+-curr5t transmission to sub/ations1 ) direct-curr5t di/ribution f sub/ations1 is ext5sively us$ on long int]urban roads1 & on l>ge city /reet-railway sy/ems :]e p[] is to be di/ribut$ ov] a wide area4 ,9 su* cases ! p[] h\se is equipp$ ) alt]nat+-curr5t dynamos supply+ high-t5sion ?ree-phase alt]nat+ curr5t to high-t5sion transmission l9es or fe$]s4 ,^! high-t5sion fe$]s are tak5 to sub/ations locat$ at v>i\s po9ts on ! road1 :]e ! voltage is r$uc$ by /ep-d[n trans=m]s2 & ^! trans=m]s supply curr5t to op]ate rot>y conv]t]s1 :i* conv]t f alt]nat+ to direct curr5t = use on ! trolley4 ,! advantage ( ?is sy/em ( high-t5sion di/ribution is t1 ow+ to ! high transmission voltage1 !re is b a small loss 9 ! high-t5sion l9es1 :i* l9es c be made v small1 & w ?us involve b little copp] inve/m5t4 ,! sub/ations c be locat$ at frequ5t int]vals1 s t ! di/ance ! #ejj-volt direct-curr5t mu/ be conduct$ to supply ! c>s is n great4 ,curr5t f "o p[] h\se c ?us be di/ribut$ ov] a v l>ge sy/em 9 cases :]e1 if ! #ejj-volt direct-curr5t sy/em ( di/ribution 7 us$1 ! co/ ( fe$]s = di/ribut+ su* a l[-voltage curr5t w\ld be prohibitive4 ,7 ! alt]nat+-curr5t high-t5sion s*eme ( di/ribution n us$1 x w\ld be necess>y to h a numb] ( small p[] h\ses at v>i\s po9ts on ! sy/em in/ead ( "o l>ge p[] h\se4 ,! co/ ( op]ation ( sev]al small p[] plants p] kil[att output1 is likely to be mu* great] ?an t ( "o l>ge p[] plant4 ,! fir/ co/ ( ! alt]nat+-curr5t di/ribut+ sy/em1 includ+ p[] h\se & sub/ations1 is likely to be consid]ably high] ?an w\ld be ! co/ ( a numb] ( small p[] h\ses2 b 9 cases :]e alt]nat+-curr5t di/ribution has be5 in/all$1 x has be5 figur$ t ! co/ ( op]ation ( ! c5tral p[] h\se ) alt]nat+-curr5t di/ribution w\ld be suffici5tly l[ z comp>$ ) sev]al small ones to pay m ?an ! int]e/ on ?is extra inve/m5t4 ,illu/ration3 ,fig4 #hg4 ,diagram ( ,di/ribut+ ,sy/em4 ,a ,sy/em ( ,di/ribution = an ,int]urban ,railway4 ,! typical features ( a high t5sion sy/em ( di/ribution = an ext5sive int]urban railway sy/em are %[n 9 ,fig4 #hg1 :i* repres5ts ! electrical transmission & di/ribution sy/em ( ! ,indiana ,union ,traction ,company4 ,! c5tral p[] /ation at ,&]son fe$s into ?irte5 rot>y conv]t] sub/ations f #g to #fe miles di/ant f ! p[] h\se4 ,! sub/ations ea/ ( ,indianapolis are f$ at #af1jjj volts & are plac$ ab\t #aa miles ap>t4 ,! sub/ations due nor? ( ,indianapolis are locat$ at int]vals ( ab\t #ag miles & are f$ at #cj1jjj volts4 ,! p[] /ation at ,&]son has a total capacity ( #e1jjj ,k4 ,w4 ,! sub/ations v>y 9 capacity f #bej to #a1ejj ,k4 ,w4 ,effici5cy ( ,transmission ,sy/ems4 ,! av]age effici5cy ( a high t5sion transmission sy/em = a c]ta9 int]urban electric railway sy/em are giv5 bel[4 ,curr5t 0 g5]at$ at #chj volts4 ,! /ep-up trans=m]s rais$ x to a pot5tial ( #af1jjj volts at :i* pressure x 0 transmitt$ to eight sub/ations at di/ances f #aj to #dj miles f ! p[] /ation4 ,x 0 !n /epp$ d[n to #chj volts & conv]t$ to direct curr5t by a rot>y conv]t]4 ,! te/s ext5d$ ov] a p]iod ( ?ree days4 ,! effici5cy ( ! /ep-up trans=m]s 0 #ie p] c5t2 ( ! high t5sion l9e #ib4i p] c5t2 ( ! /ep-d[n trans=m]s #ie p] c5t2 & ( ! rot>y conv]t]s #hh p] c5t2 giv+ a total effici5cy ( ! transmission sy/em ( #gc4e p] c5t4 ,p[] ,h\se ,location4 ,a p[] h\se is usually locat$ :]e coal & wat] supply c be *eaply obta9$4 ,= ?is reason x is plac$ ei!r on "s l9e ( railroad or :]e coal c be tak5 to x ov] ! electric railway4 ,z x is always desirable to op]ate ! eng9es 9 connection ) cond5s]s1 on acc\nt ( ! sav+ 9 fuel1 :i* is approximately #bj p] c5t ) cond5s]s1 p[] /ations are locat$1 :5 possible1 ne> riv]s & ponds f :i* a l>ge supply ( cold wat] = cond5sation ( exhau/ /eam c be obta9$4 ,:]e no su* natural wat] supply is available1 x has become cu/om>y to provide means = artificially cool+ a suffici5tly l>ge supply ( wat] = cond5sation4 ,"o me?od is to erect a numb] ( t[]s1 s con/ruct$ t ! wat] :5 pump$ to ! top w fall ?r\gh a /ructure t breaks ! wat] up into f9e spray z x falls1 ?us all[+ x to cool by evaporation s t x c be us$ aga9 = ! cond5s]s :5 x arrives at ! bottom ( ! t[]4 ,:]e m room is available1 ponds are sometimes excavat$ ne> ! p[] h\se1 & ! wat] is made to fl[ back & =? ?r\gh a s]ies ( tr\ghs locat$ above ! pond1 & x is ?us cool$4 ,:]e a p[] /ation is ( ! direct-curr5t type1 op]at+ at #ejj to #fjj volts1 x is desirable to h x z ne> ! c5t] ( electrical di/ribution z possible1 9 ord] to keep d[n ! am\nt ( inve/m5t 9 ! fe$ wire2 b x is m important to h x locat$ ne> a *eap coal & wat] supply ?an exactly at ! c5t] ( di/ribution4 ,x is also desirable to h ! /ation locat$ :]e !re is room = coal /orage1 on acc\nt ( ! *ances = int]ruption ( ! coal supply by /rikes1 railroad blockades1 & o!r causes beyond ! company's control4 ,! cont9uity ( ! coal supply is also ano!r argum5t aga9/ plac+ ! /ation :]e dep5d5ce mu/ be plac$ ^u wagons or inadequate railroad facilities4 ,coal h&l+1 aft] ! coal has rea*$ ! /ation1 is done by h& 9 ! small] p[] /ations2 b 9 l>g] p[] /ations x has come to be ! g5]al practice to d z mu* ( ! h&l+ z possible by means ( automatic coal conveyors4 ,! mo/ elaborate p[] /ations h means = dump+ coal f c>s into hopp]s1 f :i* x is convey$ by an endless *a9 provid$ ) buckets1 call$ a coal conveyor1 to /orage b9s4 ,coal conveyors also take ! coal f ! /orage b9s1 & deposit x 9 ! hopp]s ( me*anical /ok]s 9 front ( ! boil]s4 ,a%es are convey$ f "u ! boil]s by ! same k9d ( conveyors1 & are dump$ into hopp]s1 :5ce !y are drawn into c>s or wagons to be haul$ away4 ,! coal1 hav+ be5 deposit$ 9 hopp]s at ! boil] front1 is automatically f$ into ! furnaces by automatic /ok]s4 ,"o type ( automatic /ok] 9 common use is ( ! *a9-grate or l9k-belt type1 :i* is con/ruct$ l an endless sprocket *a91 ) l9ks compos$ ( heavy ca/-iron blocks t s]ve z grate b>s4 ,?is l9k belt or *a9 is kept 9 con/ant1 sl[ motion by a small /ok] eng9e or motor :i* op]ates all ! /ok]s ( a l9e ( boil]s4 ,! coal is f$ f ! hopp] on to ! *a9 grate1 & ! *a9 is sl[ly mov$ "u ! boil]s4 ,z ! coal on t "p ( ! grate "u ! boil]s is on fire1 ! fre% coal z x ent]s ! furnaces is soon ignit$4 ,! grate is run at su* a rate1 & ! ?ickness ( ! coal is s adju/$1 t ! coal is burn$ to an a% by ! "t x has travel$ to ! back ( ! furnace4 ,!re ! grate turns d[n ov] a sprocket :eel1 & ! a%es are dump$ into ! a% pit z ! grate revolves4 ,! boil]s 9 mo/ common use 9 l>ge ,am]ican electric-railway p[] h\ses are ( ! wat]-tube type1 9 :i* wat] is conta9$ inside ( a bank ( tubes1 ! ends ( ^! tubes be+ connect$ to drums or head]s4 ,! horizontal return-tubul> type ( boil] is us$ 9 _m ( ! small] p[] /ations1 & v]tical boil]s are also 9 use4 ,! eng9es 9 ! l>g] & m economical /ations are g5]ally ( ! ,corliss comp\nd-cond5s+ type1 runn+ at spe$s ( f #fj to #abj revolutions p] m9ute1 accord+ to ! size ( ! unit4 ,! small] ! unit1 ! high] ! spe$4 ,9 ! small] & old] /ations1 simple ,corliss eng9es belt$ to g5]ators are frequ5tly f\nd1 & high-spe$ eng9es also are us$4 ,x is ! almo/ univ]sal cu/om n[1 to place ! g5]ator directly on ! eng9e %aft1 mak+ a direct-connect$ unit4 ,/eam turb9es1 9 :i* ! /eam acts 9 jets aga9/ ! blades ( a turb9e :eel1 are beg9n+ to come into use at ! pres5t "t4 ,^! turb9es rotate at v high spe$1 ! l>ge/ & sl[e/ spe$-units runn+ #fjj r4p4m41 & o!rs at high] rates4 ,z ! output ( any g5]ator v>ies directly accord+ to its spe$1 a v mu* small] g5]ator c be us$ :5 c\pl$ to a high-spe$ /eam turb9e1 to obta9 a giv5 output1 ?an if ! g5]ator mu/ be c\pl$ to a ,corliss /eam eng9e :i* revolves at v l[ spe$4 ,! economy ( ! /eam turb9e at full load is ab\t t ( a comp\nd-cond5s+ ,corliss eng9e1 b is bett] on light loads ?an ! eng9e4 ,! turb9e requires less build+ space & a mu* less exp5sive f\ndation4 ,illu/ration3 ,fig4 #hh4 ,plan ( ,p[] ,h\se4 ,railway g5]ators or dynamos = direct curr5t are usually built ) comp\nd-w\nd fields1 s t1 z ! load increases1 !y w automatically raise ! voltage at _! t]m9als to comp5sate = ! drop 9 ! fe$]s & to ma9ta9 a con/ant pot5tial at ! c>s4 ,?us1 if ! l9e loss on a sy/em is #aj p] c5t1 or #ej volts at full load1 ! g5]ators w be provid$ ) %unt fields ( suffici5t /r5g? to give #ejj volts at no load1 & ) s]ies field coils :i* w add to ! field /r5g? en\gh to give #eej volts at full load4 ,! am\nt ( 8comp\nd+0--:i* is ! t]m appli$ to ?is me?od ( increas+ voltage--may be any am\nt )9 reasonable limits4 ,! pressure ma9ta9$ at diff]5t companies' electric-railway p[] h\ses v>ies1 b is usually betwe5 #ejj & #fjj volts4 ,alt]nat+-,curr5t ,g5]ators4 ,alt]nat+-curr5t g5]ators us$ = g5]at+ alt]nat+ curr5t to be di/ribut$ at high t5sion1 are g5]ally con/ruct$ to give a ?ree-phase curr5t at #be cycles p] second4 ,! voltage ( ^! alt]nat+-curr5t g5]ators is sometimes ! voltage at :i* ! p[] is to be transmitt$1 if ! di/ances are n too great4 ,a numb] ( /ations h alt]nat+-curr5t g5]ators giv+ #f1fjj volts at _! t]m9als1 :i* is a voltage well adapt$ to high-t5sion di/ribution )9 ! limits ( a l>ge city4 ,h[ev]1 g5]ators giv+ #aa1jjj volts at _! t]m9als are n[ becom+ common4 ,= high] voltages ?an ?is1 x is consid]$ necess>y to use /ep-up trans=m]s1 9 ord] to raise ! voltage to ! prop] pressure = transmission ov] long di/ances4 ,9 su* cases !re is no object 9 hav+ a high g5]ator voltage4 ,at su* /ations ! voltage ( ! g5]ators adopt$ may be any?+ desir$1 & x v>ies accord+ to ! ideas ( ! con/ruct+ eng9e]4 ,voltages ( #djj1 #a1jjj1 & #b1cjj are among ^? 9 mo/ common use4 ,d\ble-,curr5t ,g5]ators4 ,d\ble-curr5t g5]ators are sometimes us$1 :i* g5]ators w give direct curr5t at a commutator at "o end ( ! armature = use on a #ejj-volt direct-curr5t di/ribution sy/em supply+ ! trolley direct4 ,! o!r end ( ! armature has collector r+s f :i* ! ?ree-phase alt]nat+ curr5t is obta9$1 :i* c be tak5 to /ep-up trans=m]s & rais$ to a suffici5t pressure1 = high-t5sion transmission to sub/ations at di/ant p>ts ( ! road4 ,! same g5]ator c !re=e be us$ on bo? ! direct-curr5t & ! high-t5sion alt]nat+-curr5t di/ribution4 ,g5]al ,plan ( ,p[] ,/ations4 ,! g5]al plan ( an electric-railway p[] /ation is usually su* t ! build+ c be ext5d$ & m boil]s1 eng9es & g5]ators add$ )\t di/urb+ ! symmetrical design ( ! /ation4 ,?us1 ! boil]s & eng9es are plac$ z 9 ,fig4 #hh1 9 p>allel r[s1 al?\gh almo/ inv>iably 9 diff]5t rooms sep>at$ by a fire wall4 ,by add+ to ! r[ ( eng9es & to ! r[ ( boil]s1 ! /ation capacity c be increas$4 ,o!r arrangem5ts are sometimes requir$ by circum/ances2 b ?is is ! mo/ common arrangem5t & gives ! greate/ capacity ) ! m9imum am\nt ( /eam pip+4 ,l>ge /ations are sometimes con/ruct$ ) a boil] room ( sev]al floors & ) boil]s on ea* floor1 9 ord] to save gr\nd space & br+ ! boil]s ne> to ! l>ge eng9e units s t !re w n be an excessive am\nt ( /eam pip+4 ,illu/ration3 ,fig4 #hi;a4 ,g4 ,e4 ,circuit ,break]4 ,swit*bo>ds4 ,direct-curr5t /ations h swit*bo>ds1 :i* may be consid]$ "u two g5]al classes--g5]ator bo>ds & fe$] bo>ds4 ,ea* bo>d consi/s ( panels4 ,g5]ator ,d4 ,c4 ,panels4 ,! g5]ator panel usually conta9s an automatic circuit break] :i* w op5 ! ma9 circuit to ! g5]ator 9 case ( an ov]load due to a %ort circuit4 ,^! circuit break]s consi/ ( a coil 9 ! ma9 circuit1 :i* acts ^u a sol5oid4 ,:5 ! curr5t 9 ! coil exce$s a c]ta9 am\nt1 ! sol5oid is drawn 91 & a trigg] is tripp$ :i* all[s ! circuit break] to fly op5 "u ! pressure ( a spr+4 ,9 ! ,g5]al ,electric circuit break]1 ! ma9 contact is made by heavy copp] jaws1 b ! la/ break+ ( ! contact is made betwe5 po9ts :i* are "u ! influ5ce ( a magnetic field4 ,?is magnetic field bl[s out ! heavy arc t w\ld o!rwise be e/abli%$4 ,on ! ,i-,t-,e1 ! ,we/+h\se & mo/ o!r types ( circuit break]1 ! break+ ( ! contact takes place betwe5 c>bon po9ts1 :i* are n s readily de/roy$ by an arc z are copp] contacts1 & :i* are m *eaply r5ew$4 ,! ma9 contact ?r\gh ! circuit break]1 9 ei!r type1 is made betwe5 copp] jaws ( suffici5t cross-section = c>ry+ ! curr5t )\t heat+4 ,^! jaws op5 be=e ! curr5t is f9ally brok5 by ! small] contacts :i* take ! f9al arc4 ,9 ,fig4 #hi;a is se5 a ,g5]al ,electric circuit break] ) ! magnetic bl[-out coils at ! top1 ! sol5oid at ! left1 & ! h&le = resett+ ! circuit break] at ! bottom4 ,! small h&le = tripp+ ! circuit break]1 :5 x is desir$ to op5 ! circuit by h&1 is %[n j "u ! sol5oid4 ,an ,i-,t-,e circuit break] is %[n 9 ,fig4 #hi;b4 ,?is is ( ! type previ\sly m5tion$1 9 :i* ! break occurs betwe5 c>bon contacts & !re is no magnetic bl[-out4 ,illu/ration3 ,fig4 #hi;b4 ,i-,t-,e ,circuit ,break]4 ,9 addition to ! circuit break] !re is usually an ammet]1 to indicate ! curr5t pass+ f ! g5]ator2 & a rheo/at h&le1 ge>$ to a rheo/at back ( ! bo>d1 = cutt+ 9 & out m or less resi/ance 9 ! %unt field coils ( ! g5]ator s z to r$uce or raise ! voltage4 ,!re is a small swit* = op5+ & clos+ ! circuit ?r\gh ! %unt field coils4 ,! ma9 leads f ! g5]ator pass ?r\gh two s+le-pole quick-break knife swit*es4 ,! mo/ rec5t practice is to h ! swit*es on ! swit*bo>d 9 only ! positive & negative leads f ! g5]ator1 leav+ connection to ! equaliz] to be made by a swit* locat$ on or ne> ! g5]ator4 ,h[ev]1 all ?ree leads may be tak5 to ! swit*bo>d1 & a ?ree-pole knife swit* may be us$ in/ead ( ! positive & negative swit*es spok5 (4 ,9 ,fig4 #ij is giv5 a simple diagram ( ! g5]al relative connection ( g5]ators & fe$]s 9 a direct-curr5t railway p[] /ation4 ,x is se5 t ! g5]ators are connect$ 9 p>allel across ! positive & negative bus b>4 ,!re is a ?ird bus b>--call$ an 8equaliz+ bus0--:i* connects 9 p>allel ! s]ies coils ( all ! g5]ator fields4 ,! object ( ?is equaliz] is to prev5t ! weak5+ ( ! s]ies field ( any "o g5]ator1 s z to all[ x to take curr5t & to act z a motor in/ead ( z a g5]ator4 ,/>t+ ,up a ,g5]ator4 ,suppose t a new g5]ator is to be />t$ up & connect$ to ! bus b>s 9 addition to o!rs already 9 op]ation4 ,! eng9e ( t g5]ator is fir/ br\ght up to spe$4 ,! swit* controll+ ! %unt field circuit is !n clos$1 caus+ curr5t to fl[ ?r\gh ! %unt fields2 & ! g5]ator beg9s to 8build up10 its voltage gradually ris+ until x approximates t ^u ! bus b>s4 ,be=e ! g5]ator is ?r[n 9 p>allel ) ! o!rs by connect+ x ) ! bus b>s1 x is important t its voltage be ne>ly ! same z t ( ! bus b>s4 ,o!rwise1 :5 connect$ to ! bus b>s1 x might take m ?an its %>e ( ! load2 :ile1 on ! o!r h&1 if its voltage 7 too l[1 x might act z a motor1 tak+ curr5t f ! bus b>s4 ,! voltage ( ! bus b>s 9 a railway /ation is con/antly fluctuat+1 ow+ to ! v>y+ load & to ! fact t g5]ators are (t5 comp\nd$1 z be=e m5tion$1 9 ord] to comp5sate = ! l9e loss4 ,illu/ration3 ,fig4 #ij4 ,connection ( ,g5]ators & ,fe$]s4 ,9 ord] t ! voltage ( ! g5]ator to be ?r[n 9 %all v>y 9 accordance ) ! bus b> voltage1 ! next /ep 9 ! op]ation is to close ! positive swit*1 assum+ t ! equaliz] swit* on ! g5]ator has already be5 clos$4 ,?is ?r[s ! s]ies field ( ! new g5]ator 9 p>allel ) ! s]ies fields ( ! o!r g5]ators4 ,! voltage ( ! new g5]ator w !re=e v>y j z ! voltage on ! bus b>s2 &1 by adju/+ ! resi/ance ( ! %unt field1 ?is voltage c be adju/$ s z to be ! same z t on ! bus b>s4 ,! voltages on ! bus b>s & on ! new g5]ator are measur$ usually by a l>ge voltmet] on a bracket at ! end ( ! g5]ator swit*bo>d4 ,by means ( a voltmet] plug or ( a pu% button on ! g5]ator panel1 ! voltmet] c be connect$ ei!r to ! bus b>s or to ! new g5]ator4 ,:5 ! two voltages are ! same1 ! negative swit* ( ! new g5]ator c be clos$1 & x w op]ate 9 p>allel ) ! o!r g5]ators1 tak+ its %>e ( ! load4 ,if ! att5dant sees t any g5]ator is n tak+ its %>e1 he c raise its voltage by cutt+ out "s ( ! resi/ance 9 s]ies ) its %unt field1 & ?is makes t g5]ator take m load4 ,illu/ration3 ,fig4 #ia4 ,railway ,swit*bo>d4 ,fe$] ,panel4 ,! fe$] panel is simpl] ?an ! g5]ator panel1 s9ce x usually h&les only ! positive side ( ! circuit4 ,frequ5tly two fe$]s are run on a s+le panel side by side4 ,! fe$] panel has an automatic circuit break]1 an ammet] = indicat+ ! curr5t on t fe$]1 & a s+le-pole swit* = connect+ ! fe$] to ! bus b>4 ,all g5]ators fe$ into a common set ( bus b>s2 & ! positive bus b> cont9ues back ( ! fe$] panels s t all fe$]s c draw curr5t f ! bus b>s4 ,fig4 #ia %[s a railway swit*bo>d ) #g fe$] panels at ! "r2 #d g5]ator panels at ! left2 &1 9 ! middle1 a panel ) an ammet] & record+ wattmet] = measur+ total output4 ,9 "s /ations two & ev5 ?ree sets ( bus b>s are us$1 z x may be desir$ to op]ate diff]5t p>ts ( ! sy/em at diff]5t voltages or to fe$ a high] voltage to ! long] l9es ?an to ^? ne> ! /ation4 ,9 su* a case d\ble-?r[ swit*es are provid$ = connect+ fe$]s & g5]ators to ei!r set ( bus b>s4 ,alt]nat+-,curr5t ,swit*bo>ds4 ,9 an alt]nat+-curr5t /ation1 g5]ator swit*bo>ds are radically diff]5t f ^? 9 a direct-curr5t /ation4 ,practice 9 alt]nat+-curr5t g5]ator swit*bo>ds has n yet be5 s fully /&>diz$ & is n s uni=m z 9 direct-curr5t railway swit*bo>ds4 ,!re is always1 h[ev]1 a ?ree-pole ma9 swit* = op5+ & clos+ ! ma9 ?ree wires f ! ?ree-phase g5]ator4 ,automatic circuit break]s are usually provid$1 z well z indicat+ ammet]s & wattmet]s to %[ ! output4 ,indicat+ wattmet]s1 record+ ! numb] ( watt h\rs pass+ ?r\gh !m1 are frequ5tly us$ bo? on alt]nat+ & direct-curr5t g5]ator panels4 ,a /ation usually has :at is call$ a 8total load0 panel1 :i* has a record+ wattmet] measur+ ! total output ( ! /ation 9 kil[att h\rs4 ,?is panel also has an ammet] indicat+ ! total /ation load4 ,high-,t5sion ,oil ,swit*es4 ,alt]nat+-curr5t g5]ators = high voltages usually h oil swit*es to int]rupt ! ma9 circuit1 t is1 swit*es 9 :i* ! contact is made & brok5 "u oil4 ,^! swit*es h be5 f\nd v effici5t 9 prev5t+ ! =mation ( a de/ructive arc ^u ! op5+ ( a high-voltage circuit1 on circuits up to #fj1jjj volts4 ,"s ( ! l>g] oil swit*es are op]at$ by electric motors or sol5oids4 ,! ma*9e-type oil swit* ( ! ,g5]al ,electric ,company has ! motive p[] = op]at+ ! swit*es1 /or$ up 9 a spr+4 ,! spr+ is w\nd up by a small electric motor4 ,?is motor op]ates e "t ! swit* is op5$ or clos$1 & w9ds up ! spr+ en\gh to comp5sate = ! am\nt x 0 unw\nd 9 op]at+ ! swit*4 ,ea* circuit is brok5 "u oil 9 a long tube1 & ^! tubes are m\nt$ 9 individual cells1 ea* cell be+ sep>at$ f ! next by a masonry wall s t !re c be no fla%+ across f "o leg ( ! circuit to ano!r 9 case ( any defect 9 ! swit*4 ,all ! high-t5sion wir+ to & f su* swit*es1 is tak5 ei!r 9 lead-cov]$ cables1 or on bus b>s sep>at$ f ea* o!r by masonry walls to prev5t ! spread ( %ort circuits4 ,^! precautions are necess>y because ( ! great l5g? ( arc t may be e/abli%$ betwe5 adjac5t high-t5sion conductors4 ,:]e alt]nat+-curr5t g5]ators ( l[ voltage are us$ 9 connection ) /ep-up trans=m]s1 "o practice is to h ! swit*es = ea* g5]ator directly 9 ! g5]ator leads1 betwe5 ! g5]ators & ! /ep-up trans=m]s1 9 ! l[-voltage circuit4 ,ano!r practice :i* has rec5tly be5 introduc$1 is to consid] ea* g5]ator ) its /ep-up trans=m]s z a unit & to connect ! g5]ator p]man5tly ) its bank ( trans=m]s1 & to control ?is unit by a s+le ?ree-pole ma*9e-op]at$ oil swit*4 ,9 ?is case !re are no swit*bo>d swit*es betwe5 g5]ators & trans=m]s1 & ?is simplifies ! swit*bo>d consid]ably4 ,!re mu/ be swit*es on ! high-t5sion side ( ! trans=m]s 9 any ev5t4 ,! swit*bo>d = rot>y conv]t]s 9 ! sub/ations is1 ( c\rse1 a comb9ation ( alt]nat+ & direct-curr5t app>atus4 ,! direct-curr5t ends ( ! rot>y conv]t]s are treat$ almo/ exactly l direct-curr5t railway g5]ators2 & _! swit*bo>d panels are simil>ly equipp$1 except t usually !re is a rheo/at t c be connect$ 9 s]ies ) ! armature :]eby a rot>y conv]t] c be br\ght up to spe$ f a /ate ( re/ by connect+ x ) ! direct-curr5t bus b>s ( ! sub/ation4 ,! alt]nat+-curr5t end ( ! rot>y conv]t] is suppli$ ?r\gh swit*es 9 ! alt]nat+-curr5t leads f ! /ep-d[n trans=m]s4 ,a rot>y conv]t] c be />t$ f a /ate ( re/ by connect+ x to ! alt]nat+-curr5t leads ?r\gh ! m$ium ( comp5sat+ coils :i* r$uce ! voltage4 ,a v heavy curr5t is requir$ to d ?is1 z ! motor ?us />ts z a v ineffici5t induction motor ) a v l[ p[] factor4 ,illu/ration3 ,fig4 #ib4 ,connection ( ,sub/ations4 ,!re are usually b two direct-curr5t fe$] panels 9 a sub/ation ( an int]urban electric road4 ,"o ( ^! fe$]s is to supply ! trolley or ?ird rail ext5d+ 9 "o direction f ! sub/ation1 & ! o!r fe$s t ext5d+ 9 ! o!r direction f ! sub/ation4 ,! trolley or ?ird rail has a section insulator directly at ! sub/ation4 ,:5 bo? fe$]s are connect$ to ! bus b>s1 x is evid5t t ?is section insulator is %ort-circuit$ ?r\gh ! m$ium ( ! sub/ation bus b>s1 e sub/ation on ! l9e be+ connect$ 9 ?is way1 z indicat$ 9 ,fig4 #ib4 ,x is se5 t1 %\ld a %ort circuit occur on any section1 x w\ld op5 ! circuit break]s at ! sub/ations at bo? ends1 & t section w\ld n int]f]e ) ! balance ( ! road4 ,at ! same "t1 :5 ! road is 9 normal op]ation & !re is an unusually heavy load betwe5 any two sub/ations1 ! o!r sub/ations along ! l9e c help out ^? ne>e/ to ! load by fe$+ ?r\gh ! bus b>s ( ! ne>e/ sub/ation4 ,! high-t5sion app>atus at a sub/ation consi/s usually ( a bank ( high-t5sion lightn+ arre/]s2 high-t5sion swit*es1 = %utt+ (f ! high-t5sion curr5t2 & /ep-d[n trans=m]s1 = r$uc+ f ! high transmission voltage to ! #cgj volts commonly f$ to ! alt]nat+-curr5t end ( railway rot>y conv]t]s4 ,/orage ,batt]ies 9 ,/ations4 ,/orage batt]ies are frequ5tly us$ bo? 9 sub/ations & 9 direct-curr5t p[] /ations4 ,!y may be connect$ directly across ! l9e & all[$ to 8float10 z x is t]m$2 or !y may be us$ 9 connection ) /orage-batt]y boo/]s1 :i* w cause ! /orage batt]y to take ! fluctuations 9 ! load & to give a con/ant load on ! rot>y conv]t]s or p[] /ation4 ,! action ( /orage-batt]y boo/]s :i* cause ! /orage batt]y to be *>g$ automatically at light loads & to dis*>ge & assi/ ! /ation at heavy loads1 is expla9$ 9 ! pap] on 8,/orage ,batt]ies40 ,,alt]nat+-,,curr5t ,,sy/ems4 ,s f> ?is pap] has be5 devot$ almo/ entirely to electric railway sy/ems employ+ #ejj-volt direct-curr5t motors on ! c>s1 s9ce ?is is ! sy/em almo/ univ]sally employ$ on electric railways at ! pres5t "t4 ,!re are1 h[ev]1 sev]al sy/ems employ+ alt]nat+-curr5t motors on c>s1 :i* h already be5 us$ exp]im5tally & to "s ext5t comm]cially4 ,"s ( ^! give promise ( com+ into ext5sive use4 ,?ree-,phase ,motors4 ,on sev]al roads 9 ,europe ?ree-phase induction motors are employ$4 ,^! induction motors are op]at$ by ?ree-phase alt]nat+ curr5t tak5 direct f ! trolley wires4 ,z ?ree conductors are necess>y1 two trolley wires are us$1 ) ! rails z ! ?ird conductor4 ,! two pr9cipal objections to ! sy/em are ! necessity ( two trolley wires1 & ! fact t ! induction motor op]ates v mu* l a direct-curr5t %unt motor 9 t x is a con/ant-spe$ motor & n adapt$ to v>iable-spe$ "w4 ,! p[] factor is l[ 9 />t+2 t is1 a great volume ( curr5t is tak51 al?\gh1 ow+ to ! voltage & ! curr5t n be+ 9 phase1 ! actual en]gy consum$ is small4 ,s+le-,phase ,motors4 ,! ,we/+h\se ,electric ,manufactur+ ,company has br\ght out a railway motor adapt$ to op]ate on s+le-phase alt]nat+-curr5t circuits4 ,?is motor is v simil> 9 con/ruction to ! ord9>y s]ies-w\nd #ejj-volt direct-curr5t railway motor4 ,x has1 h[ev]1 m field poles ?an ! ord9>y direct-curr5t motor2 & ! pole pieces are lam9at$ to avoid heat+ ( ! iron by eddy curr5ts caus$ by ! influ5ce ( ! alt]nat+ curr5t4 ,!re are also o!r special features 9 ! design t r$uce ! sp>k+ at ! commutator1 :i* sp>k+ 0 = sev]al ye>s ! greate/ ob/acle to ! use ( alt]nat+-curr5t motors ( ?is k9d4 ,9 ! ,we/+h\se sy/em ! curr5t is tak5 f ! trolley wire at high pot5tial1 & is r$uc$ by an auto-trans=m] on ! c>4 ,?is auto-trans=m] is connect$ ) an induction regulator s arrang$ t a l[ voltage c be suppli$ to ! motor 9 />t+ or = sl[ runn+1 & ?is voltage increas$ to increase ! spe$4 ,!re is ?us no ne$ to r$uce ! trolley voltage by wa/+ "p ( x 9 a rheo/at1 z is ! case ) direct-curr5t motors2 & ! effici5cy dur+ accel]ation is1 !re=e1 high] ) ?is alt]nat+ sy/em ?an ) ! direct curr5t4 ,sev]al o!r s+le-phase railway motors are also be+ work$ out at ! pres5t "t1 includ+ t ( ! ,g5]al ,electric ,company4 ,alt]nat+-,curr5t ,motor ,advantages4 ,!re are two great advantages secur$ by ! use ( an alt]nat+-curr5t railway motor4 ,! fir/ is a r$uction 9 inve/m5t & op]at+ exp5ses by do+ away ) sub/ations conta9+ rot>y conv]t]s4 ,su* sub/ations are necess>y on long l9es ( railway op]at+ ) direct-curr5t motors4 ,! second advantage is t1 ow+ to ! fact t a high t5sion curr5t c be us$ on ! trolley wire & r$uc$ by a trans=m] on ! c>1 ! difficulties ( collect+ a l>ge am\nt ( en]gy f a trolley wire are mu* r$uc$4 ,fir/1 9 reg>d to ! sub/ations1 x w be se5 t ) ! alt]nat+-curr5t motor sy/em1 high-t5sion curr5t c be conduct$ f ! p[] h\se to sub/ations along ! l9e :i* conta9 no?+ b /atic trans=m]s4 ,s9ce ^! trans=m]s h no revolv+ p>ts !y d n require ! con/ant att5dance t a rot>y conv]t] does4 ,fur!rmore1 ! inve/m5t 9 rot>y conv]t]s is entirely disp5s$ )1 & ?is makes a consid]able r$uction 9 ! total co/ ( ! di/ribution plant4 ,) ! alt]nat+-curr5t sy/em1 curr5t is f$ direct to ! trolley wire f ! second>y t]m9als ( ! trans=m]s at ! sub/ations4 ,z reg>ds ! advantages ( c>ry+ a high voltage on ! trolley wire1 x w readily be se5 t1 s9ce ! am\nt ( p[]1 or ! watts requir$ by a c>1 is equal to ! product ( ! voltage & curr5t1 an increase 9 ! voltage r$uces ! volume ( curr5t necess>y4 ,by hav+ high voltage on ! trolley wire1 ev5 a l>ge c> c be op]at$ ) a small volume ( curr5t1 & ?is curr5t c be tak5 ?r\gh an ord9>y trolley :eel )\t difficulty4 ,:]e #ejj volts is ! pressure us$ on ! trolley wire1 !re is consid]able fla%+ & burn+ ( trolley :eel & wire :5 l>ge c>s & locomotives are run1 ow+ to ! heavy curr5t conduct$2 & ?is has be5 "o ( ! pr9cipal reasons = ! adoption ( ! ?ird rail in/ead ( ! trolley on c]ta9 roads4 ,ev5 ) ! ?ird rail1 ! volume ( curr5t t mu/ be conduct$ to l>ge electric locomotives involves "s difficulties 9 ! way ( heat$ contact %oes & consid]able loss ( en]gy4 ,! use ( high voltage on ! trolley wire1 ) trans=m]s on ! c> to r$uce ! voltage to a safe pressure = use on ! motors1 ov]comes _m ( ! difficulties t w\ld o!rwise be f\nd 9 ! use ( electricity = heavy railroad "w4 ,,op]ation4 ,p[] ,tak5 by ,c>s4 ,! am\nt ( p[] requir$ 9 ! practical op]ation ( a c> dep5ds ^u s _m v>iable elem5ts t _m ( ! calculations sometimes giv5 = det]m9+ ! p[] requir$ by a c> are ( little value4 ,! !oretical horsep[] requir$ to ma9ta9 a c> at a c]ta9 spe$ on a level1 is evid5tly ! tractive ef=t 9 p\nds multipli$ by ! spe$ 9 feet p] m9ute & divid$ by #cc1jjj4 ,:at ! tractive ef=t p] ton ( c> w be1 dep5ds on ! condition ( ! rail & on sev]al o!r unc]ta9 factors4 ,= /reet-railway motor c>s1 #bj p\nds p] ton is ! usual tractive ef=t assum$ z necess>y4 ,a calculation ( ?is k9d1 h[ev]1 takes no acc\nt ( ! losses 9 ! motors & ge>s1 nor ( ! fact t ! great] "p ( ! p[] requir$ to propel a /reet c> 9 practical s]vice is us$ 9 accel]at+ ! c> f a /ate ( re/ to full spe$4 ,9 int]urban s]vice1 ( c\rse1 ! p[] requir$ 9 accel]ation is n s great a proportion ( ! :ole4 ,illu/ration3 ,fig4 #ic4 ,plott$ ,data ( ,road ,te/4 ,! safe/ figures to use 9 eng9e]+ calculations z to ! am\nt ( p[] requir$1 are ^? tak5 f actual results obta9$ 9 ev]yday comm]cial s]vice4 ,! p[] requir$ by an eight-ton c> 9 s]vice 9 a l>ge city l ,*icago1 is 9 ! neighborhood ( "o kil[att h\r p] c>-mile run4 ,on outly+ l9es ?is figure may be r$uc$ to 4#g kil[att h\r1 & 9 ! d[n-t[n di/ricts may run up to #a4e kil[att h\rs p] c> mile4 ,d\ble-truck c>s 9 city s]vice1 weigh+ f #bj to #be tons1 take f #b to #d kil[att h\rs p] c> mile at ! p[] /ation4 ,int]urban c>s ar\nd ,detroit1 weigh+ ab\t #cb tons1 9 int]urban s]vice1 mak+ #be miles p] h\r1 includ+ /ops1 9 level c\ntry1 & ge>$ to #dc miles p] h\r1 take ab\t #c kil[att h\rs p] c> mile at ! p[] /ation4 ,h[ev]1 int]urban railway conditions are extremely v>iable4 ,! reports ( sev]al ,indiana electric railways %[ an av]age p[] consumption ( #a4dh kil[att h\rs p] c> mile = city c>s & #e4ah kil[att h\rs = int]urban c>s1 includ+ l9e & di/ribution losses4 ,an int]urban c> weigh+ #ca tons & equipp$ ) two #aej horsep[] motors1 on a te/ run ( #ej miles at an av]age spe$ ( #ci miles p] h\r consum$ #b4bj kil[att h\rs p] c> mile4 ,?is c> made #ah /ops4 ,a simil> c> "u ! same conditions made ! same run at an av]age spe$ ( #bf miles p] h\r ) #dd /ops1 consum$ #b4dd kil[att h\rs & a ?ird c>1 mak+ #ab /ops & at a spe$ ( #cc miles p] h\r1 consum$ #b4aj kil[att h\rs p] c> mile4 ,^! individual c> te/ figures are f measurem5ts tak5 at ! c> & d n include l9e losses4 ,road ,te/s ( ,electric ,c>s4 ,( late consid]able att5tion has be5 giv5 to mak+ road te/s ( electric c>s4 ,! results ( ! te/s are usually plott$ 9 ! =m %[n 9 ,fig4 #ic4 ,"t is plott$ horizontally 9 seconds1 :ile volts1 amp]es1 spe$ & p] c5t grade are plott$ v]tically4 ,! diagram ref]r$ to is ! result ( a cont9u\s run ( #f m9utes ( a #cb4e ton c> equipp$ ) two motors4 ,! l9e voltage1 motor consumption & o!r read+s may be obta9$ = any in/ant ( "t4 ,! accel]ation 9 miles p] h\r p] second may be obta9$ by not+ ! increase 9 height ( ! spe$ curve 9 "o second4 ,9 mak+ su* a te/ ! necess>y in/rum5ts1 voltmet]s1 ammet]s1 wattmet]s & spe$ indicators are m\nt$ direct on ! c> & are read at int]vals ( a few seconds4 ,! curve ( motor consumption gives an idea ( ! abnormal curr5t requir$ to get ! c> "u headway4 ,economy 9 ,p[]4 ,z already /at$1 a l>ge "p ( ! en]gy tak5 by a c> 9 city s]vice is us$ 9 accel]at+ ! c>4 ,mu* ( ?is en]gy mu/ be de/roy$ or us$ up 9 ! brake %oes at ! next /op4 ,! en]gy /or$ up 9 a c> by process ( accel]ation is repres5t$ by ! =mula3 ,mass 9 lbs4 7,velocity 9 ft4 p] sec47 ,en]gy 9 ft4 lbs4 ---------------------------------------- ---------------------------------------- ----1 :i* #b is ! =mula = k9etic or live en]gy1 ! d]ivation ( :i* is f\nd 9 any ,in/ruction ,pap] on ,me*anics4 ,9 p]=m+ any giv5 s*$ule ) frequ5t /ops1 ! m rapid ! accel]ation ! l[] ! maximum spe$ requir$ to make ! s*$ule1 & ! less ! en]gy requir$ 9 accel]ation4 ,= city /reet & elevat$ s]vice1 !re=e1 rapid accel]ation & l[ maximum spe$s are desirable because n only m economical b saf]4 ,= economical op]ation ) any giv5 equipm5t & s*$ule1 x is important to use z mu* ( ! en]gy /or$ up 9 ! c> z possible1 be=e wa/+ x by apply+ ! brakes4 ,motors are built ( a size to yield ! l>ge horsep[] requir$ 9 accel]ation1 & consequ5tly are lightly load$ :5 op]at+ ! c> at maximum spe$4 ,to economize 9 p[]1 curr5t %\ld be %ut (f z soon z possible aft] ! c> has atta9$ full spe$2 & ! c> %\ld be all[$ to drift )\t curr5t z long z possible be=e ! brakes are appli$4 ,9 ?is way ! en]gy /or$ 9 ! c> w propel x at ne>ly maximum spe$ = a consid]able di/ance betwe5 /ops2 !re w be ! smalle/ possible wa/e ( en]gy 9 ! brake %oes2 & ! losses ( en]gy :i* take place :5 ! curr5t is 9 ! motors w be prev5t$ z f> z possible4 ,practical te/s z well z !oretical calculations %[ a possibility ( v mat]ial sav+ 9 en]gy 9 ! op]ation ( an electric railway c> or tra91 by ! obs]vance ( ?is simple rule ( drift+ z mu* z possible & us+ ! brakes z little z possible4 ,:atev] en]gy is us$ up 9 ! brake %oes is necess>ily wa/$4 ,! small] ?is wa/e c be kept :ile p]=m+ a giv5 s]vice1 ! great] ! economy secur$4 ,co/ ( ,p[]4 ,! reports ( #he p] c5t ( ! railway p[] g5]at+ /ations 9 ,indiana %[ ! av]age co/ at ! /ation p] kil[att h\r to be 4#gee c5t4 ,?is 0 divid$ z foll[s3 ,fuel 4#ebf c5ts1 labor 4#aeh c5ts1 lubricants & miscellane\s supplies 4#jcb c5ts1 repairs 4#jci c5ts4 ,! l[e/ co/ report$ 0 4#eje c5ts4 ,dur+ #aija ! av]age co/ ( p[] g5]at$ at ! p[] h\se ( ! ,indiana ,union ,traction ,company 0 4#ddc c5ts p] kil[att h\r at ! swit*bo>d4 ,di/ribut$ f ! sub/ations x 0 4#gfe c5ts p] kil[att h\r4 ,natural gas 0 us$ = fuel4 ,on occasions :5 ?is fail$1 coal at #a4ej p] ton 0 burn$4 ,slid+ & ,sp9n+ ,:eels4 ,9 accel]at+ a c>1 h[ev]1 !re is no economy 9 turn+ on curr5t s rapidly z to sp9 ! :eels4 ,z m5tion$ 9 ! section on 8,brakes10 ! tractive ef=t betwe5 :eels & rails falls (f ab\t two-?irds :5 ! :eels beg9 to slip2 & ?is slipp+ ( :eels1 !re=e1 r$uces ! *ance ( secur+ ! accel]ation :i* is possible4 ,= ! same reason1 9 mak+ em]g5cy /ops ei!r by ! use ( brakes or by rev]s+ ! motors1 c>e %\ld be tak5 n to slide ! :eels1 z by s do+ ! "t requir$ to /op ! c> is mu* increas$4 ,9 ! ord9>y /raight air-brake equipm5t us$ on heavy electric c>s1 !re is mu* high] pressure c>ri$ 9 ! /orage res]voir ?an x is p]missible to turn into ! brake cyl9d]1 s9ce1 if ! full pressure 7 turn$ into ! brake cyl9d]1 x w\ld result 9 slid+ ( ! :eels--:i*1 x has j be5 %[n1 is some?+ to be avoid$1 n only on acc\nt ( mak+ flat spots on ! :eels1 b also because ( ! r$uction 9 ! brak+ =ce z soon z ! :eels beg9 to slide4 ,an exp]i5c$ motorman c tell f ! feel+ ( ! c> :5 ! :eels are slid+1 & w in/antly release ! brake suffici5tly to all[ ! :eels to beg9 to revolve z soon z he notices t ?is has tak5 place4 ,! friction betwe5 brake %oes & c> :eels decreases z ! spe$ increases4 ,a c]ta9 pressure appli$ to ! brake %oes ^u a c> runn+ #ej miles p] h\r1 !re=e1 ex]ts mu* less ret>d+ =ce ?an ! same pressure at t5 miles p] h\r4 ,9 ord] to give ! same brak+ or ret>d+ =ce at high] spe$s1 ! brakes mu/ be appli$ h>d] ?an at ! l[] spe$s4 ,if !y are appli$ at ! maximum pressure possible )\t slid+ ! :eels at high] spe$s1 x is evid5t t ?is pressure mu/ be r$uc$ z ! spe$ ( ! c> is r$uc$1 or ! :eels w be 8skidd$40 ,9 ! ,we/+h\se high-spe$ automatic air brake us$ on /eam roads1 ?is r$uction ( pressure is automatically accompli%$4 ,,te/+ ,,= ,,faults4 ,illu/ration3 ,fig4 #id4 ,bond ,te/+4 ,bond ,te/+4 ,x is important to te/ ! conductivity ( rail bonds f "t to "t 9 ord] to det]m9e if !y h det]iorat$ s z to r$uce _! conductivity & introduce an unnecess>y am\nt ( resi/ance into ! return circuits4 ,"o way ( do+ ?is is to measure ! drop 9 pot5tial ov] a bond$ jo9t z comp>$ ) ! drop 9 pot5tial ( an equal l5g? ( unbrok5 rail4 ,to d ?is1 an app>atus is employ$ :]eby simultane\s contact w be made bridg+ ?ree or m feet ( rail & an equal l5g? ( rail includ+ ! bond$ jo9t1 z %[n 9 ,fig4 #id1 :i* illu/rates ! connections ( a common =m ( app>atus :]e two milli-voltmet]s are employ$ t measure ! drop 9 voltage ( ! bond$ & unbond$ rail simultane\sly4 ,if ! curr5t fl[+ ?r\gh ! rail due to ! op]ation ( ! c>s 7 con/ant1 ( c\rse "o milli-voltmet] might be us$1 be+ connect$ fir/ to "o circuit & !n to ! o!r4 ,! curr5t 9 ! rail1 h[ev]1 fluctuates rapidly1 s t two in/rum5ts are necess>y = rapid "w4 ,! resi/ance ( ! bond$ jo9t is usually consid]ably m ?an t ( ! unbrok5 rail1 & ! milli-voltmet] us$ to bridge ! jo9t consequ5tly ne$ n be s s5sitive z t bridg+ ! unbrok5 rail4 ,9 ano!r =m ( app>atus1 a telephone receiv] is us$ in/ead ( ! milli-voltmet]1 ! resi/ance ( a long unbrok5 rail be+ balanc$ aga9/ t ( ! bond$ jo9t1 z 9 a ,:eat/one bridge1 until1 ^u clos+ ! circuit1 ^! two resi/ances :5 balanc$ give no s\nd 9 ! telephone receiv]4 ,bond te/s ( ?is k9d c be made ) satisfaction only :5 a consid]able volume ( curr5t is fl[+ ?r\gh ! rails at ! "t ( ! te/1 because ! drop 9 voltage is dep5d5t on ! curr5t fl[+1 & 9 any ev5t is small4 ,x has sometimes be5 f\nd necess>y or advisable to fit up a te/+ c> equipp$ ) a rheo/at :i* w itself use a consid]able volume ( curr5t1 s z to give a curr5t 9 ! rail :i* w give an appreciable drop ( pot5tial across a bond$ jo9t4 ,"s ( ! late/ =ms ( te/+ c>s c>ry motor g5]ators :i* w pass a l>ge curr5t ( kn[n value ?r\gh a bond$ jo9t1 & s cause a drop ( pot5tial across ! jo9t l>ge en\gh to be easily measur$4 ,motor-,coil ,te/+4 ,te/+ = faults 9 ! motor armature & field coils is done 9 a great v>iety ( ways4 ,! resi/ance ( ^! coils c be measur$ by means ( a ,:eat/one bridge employ+ a telephone receiv] 9 place ( ! galvanomet] us$ 9 su* bridges 9 laboratory practice2 b o!r less delicate te/s are also 9 use4 ,ano!r me?od is to pass a kn[n curr5t ?r\gh ! coil to be te/$ & to measure ! drop 9 ! voltage betwe5 ! t]m9als ( ! coil1 ! voltage divid$ by ! curr5t equal+ ! resi/ance4 ,a simple me?od1 & "o :i* involves no delicate in/rum5ts1 has lately be5 introduc$ into railway %op practice v successfully4 ,?is is kn[n z ! trans=m] te/ = %ort-circuit$ coils4 ,x requires an alt]nat+ curr5t :i* c easily be suppli$ ei!r by a regul> motor g5]ator or by putt+ collect+ r+s onto an ord9>y direct-curr5t motor & connect+ ^! r+s to b>s ( opposite pol>ity on ! commutator4 ,! me?od ( te/+ = %ort-circuit$ armature coils employ$ 9 ! %ops ( ! ,/4 ,l\is ,transit ,company is indicat$ 9 diagram 9 ,fig4 #ie4 ,a core built up ( s(t lam9at$ iron is w\nd ) #bh turns ( ,no4 #f copp] wire4 ,?is coil is suppli$ ) alt]nat+ curr5t f a #aaj-volt circuit4 ,! core has pole pieces made to fit ! surface ( ! armature4 ,:5 "o side ( a %ort-circuit$ coil 9 ! armature is br\ght betwe5 ! pole pieces ( ?is te/+ trans=m]1 z 9 ,fig4 #ie1 ! %ort-circuit$ armature coil becomes l ! %ort-circuit$ second>y ( a trans=m]1 & a l>ge curr5t w fl[ 9 x4 ,?is curr5t w 9 "t manife/ itself by heat+ ! coil2 b x is n necess>y to wait = ?is1 z a piece ( iron held ov] t side ( ! coil n enclos$ betwe5 ! pole pieces1 z indicat$ 94 ,fig4 #ie1 w be attract$ to ! face ( ! armature if held directly ov] ! coil1 b w be attract$ at no o!r po9t4 ,illu/ration3 ,fig4 #ie4 ,me?od ( ,te/+ = ,%ort-circuit$ ,armature ,coils4 ,?is te/+ c be done v rapidly1 & does n require delicate in/rum5ts or skill$ op]ators4 ,te/s = %ort circuits 9 field coils c be made 9 a simil> mann]1 by plac+ ! coils on a core :i* is magnetiz$ by alt]nat+ curr5t4 ,! pres5ce ( a %ort circuit1 ev5 ( "o convolution ( a field coil1 w be app>5t f ! increase 9 ! alt]nat+ curr5t requir$ to magnetize ! core ^u :i* ! field coil is be+ te/$4 ,! insulation resi/ance ( armatures & fields is frequ5tly te/$ by means ( alt]nat+ curr5t1 ab\t #b1jjj volts be+ ! common te/+ voltage = #ejj-volt motor coils4 ,"o t]m9al ( ! te/+ circuit is connect$ to ! frame ( ! motor1 & ! o!r to its w9d+s4 ,any weakness 9 ! insulation insuffici5t to )/& #b1jjj volts w1 ( c\rse1 be brok5 d[n by ?is te/4 ,alt]nat+ curr5t is g5]ally us$ = su* te/s because x is usually m easily obta9$ at ! prop] voltage1 z x is a simple matt] to put 9 an alt]nat+ trans=m] :i* w give any desir$ voltage & :i* c be controll$ by a prim>y circuit ( l[ voltage4 ,op5 circuits 9 ! armature c be easily detect$ by plac+ ! armature 9 a frame s t x c be rotat$1 ! frame be+ provid$ ) bru%es re/+ #ij ap>t on ! commutator4 ,if ei!r an alt]nat+ or direct curr5t be pass$ ?r\gh ! armature by means ( ^! bru%es1 & ! armature be rotat$ by h&1 a fla% w occur :5 ! op5-circuit$ coils pass "u ! bru%es4 ,a l>ge curr5t %\ld be us$4 ,! te/s j m5tion$ are among ! be/ ( ! me?ods us$ by electric-railway companies = sy/ematic "w 9 ! location ( c]ta9 classes ( faults4 ,a l>ge numb] ( o!r me?ods ( te/+ h also be5 evolv$4 ,! foll[+ are "s ( ! mo/ common faults exp]i5c$ ) electric railway c> equipm5ts3 ,gr\nds4 ,z "o side ( ! circuit is gr\nd$1 any accid5tal leakage ( curr5t f ! c> wir+ or ! motors to gr\nd w cause a p>tial %ort circuit4 ,su* a gr\nd on a motor w manife/ itself by bl[+ ! fuse or op5+ ! circuit break] :5ev] curr5t is turn$ into ! motor4 ,9 case ! fuse bl[s :5 ! trolley is plac$ on ! wire & ! controll] is (f1 x is a sign t !re is a gr\nd some:]e 9 ! c> wir+ outside ( ! motors4 ,moi/ure & ! abrasion ( wires are ! mo/ common causes ( gr\nds 9 c> wir+4 ,9 motors1 defects are usually due to ov]heat+ & ! *>r+ ( ! insulation4 ,burn-,outs4 ,burn+ out ( motors is due to two g5]al causes3 ,fir/1 a gr\nd on ! motor1 :i*1 by caus+ a p>tial %ort circuit1 causes an excessive curr5t to fl[2 second1 ov]load+ ! motor1 :i* causes a gradual burn+ or c>boniz+ ( ! insulation until x f9ally breaks d[n4 ,%ort-circuit$ field coils hav+ a few ( _! turns %ort-circuit$1 if n promptly discov]$1 are likely to result 9 burn$-out armatures1 z ! weak5+ ( ! field r$uces ! c\nt]-electromotive =ce ( ! motor1 s t an abnormally l>ge curr5t fl[s ?r\gh ! armatures4 ,c>s ) p>tially %ort-circuit$ fields are likely to run above _! prop] spe$1 ?\gh1 if only "o motor on a f\r-motor equipm5t has defective fields1 ! motor armature is likely to burn out be=e ! defect is notic$ f ! increase 9 spe$4 ,illu/ration3 ,fig4 #if4 ,defects ( ,armature ,w9d+s4 ,defects 9 armature w9d+s probably cause "o-?ird ! ma9t5ance exp5ses ( electrical equipm5t ( c>s4 ,almo/ all repair %ops h m5 cont9ually employ$ 9 repair+ !m4 ,! mo/ frequ5t tr\ble ) armatures is ?r\gh failure ( ! insulation ( ! coils & consequ5t 8gr\nd+40 ,?is t]m is us$ 9 connection ) armatures & fields & o!r electrical app>atus :]e a direct pa? exi/s to gr\nd4 ,z ! armature core is electrically connect$ to ! gr\nd ?r\gh its be>+s & ! motor cas+1 a break d[n ( ! insulation ( ! coils 9 ! slots p]mits ! curr5t to pass directly to gr\nd4 ,?is %unts ! curr5t ar\nd ! fields & an abnormal curr5t fl[s because ( _! weakness4 ,! circuit break] or fuse is plac$ 9 circuit to protect ! app>atus 9 su* an em]g5cy1 b usually be=e su* devices break ! circuit1 sev]al ( ! coils ( ! armature are burn$ 9 su* a mann] z to make _! removal necess>y4 ,! coils are s w\nd on top ( "o ano!r t 9 ord] to replace "o coil alone1 "o-f\r? ( ! coils ( ! armature mu/ be lift$4 ,illu/ration3 ,fig4 #ig4 ,) ! armature ( ,no4 #a motor gr\nd$ ! c> w n op]ate & if ! resi/ance po9ts be pass$ ov]1 ! fuse w usually bl[4 ,:5 ,no4 #b motor is gr\nd$ ! action ( ,no4 #a motor is n impair$ & ?is latt] motor w pull ! c> until ! controll] is ?r[n to ! multiple position4 ,b if ! motors are ?r[n 9 multiple1 ! pa? ?r\gh ! gr\nd ( ,no4 #b motor %unts motor ,no4 #a4 ,a /udy ( ,fig4 #ah w make ?is evid5t4 ,illu/ration3 ,fig4 #ih4 ,next to gr\nd+1 op5 circuits are ! mo/ s]i\s defects ( armatures4 ,^! are usually caus$ by burn+ 9 two ( ! wires 9 ! slot1 or :]e !y cross "o ano!r 9 pass+ to ! commutator4 ,sometimes ! connections :]e ! leads are sold]$ to ! commutator become loose4 ,! effect ( an op5 circuit is %[n 9 ,fig4 #if4 ,! circuit is op5 at n4 ,! bru%es are on segm5ts a & d4 ,by trac+ out ! w9d+ x w be f\nd t no curr5t fl[s ?r\gh ! wires m>k$ 9 heavy l9es4 ,:5ev] segm5ts c & d are "u a bru% ! coil ) ! op5 circuit is bridg$ by ! bru% & curr5t fl[s z 9 a normal armature4 ,z segm5t c passes out f "u ! bru% ! op5 circuit int]rupts ! curr5t 9 half ! armature & a long flam+ arc is drawn out4 ,9 ,fig4 #ig is %[n ! result ( a %ort circuit betwe5 two coils4 ,! %ort circuit is at b1 c1 ! two leads com+ 9 contact ) ea* o!r :5 !y cross4 ,! effect is to %ort-circuit all ( ! w9d+ indicat$ by ! heavy l9es4 ,illu/ration3 ,fig4 #ii4 ,mi/akes 9 ,w9d+ ,armatures4 ,! armature w9d] is giv5 v simple rules z to h[ to w9d ! armature1 b ! great numb] ( leads ea* to be connect$ to _! prop] commutator segm5t sometimes s confuse him t misconnections are made4 ,! effect ( gett+ two leads cross$ is %[n 9 ,fig4 #ih4 ,! leads to segm5ts b & c f ! "r are %[n int]*ang$4 ,?is %ort-circuits ! coils %[n 9 heavy l9es4 ,! abnormal curr5t result+ 9 ^! w\ld usually cause !m to burn out4 ,fig4 #ii %[s ! results ( plac+ all ( ! top leads1 or all ( ! bottom leads "o segm5t beyond ! prop] position4 ,?is causes ! circuit />t+ f a & travel+ c\nt] clockwise ar\nd ! armature to return on segm5t m in/ead ( on segm5t b z is ! case 9 ,fig4 #ig4 ,! only result ( su* connections is to *ange ! direction ( rotation ( ! armature4 ,x may be notic$ by comp>+ ! two figures t ) ! positive bru% on segm5ts a ! arr[s %[ ! curr5ts to be 9 opposite directions 9 coils simil>ly locat$ ) ref]5ce to ! position ( ! bru%es4 ,"s armatures are int5d$ to be w\nd z 9 ! la/ case m5tion$4 ,sp>k+ at ! ,commutator4 ,z railway motors are made to op]ate1 & usually d op]ate1 almo/ sp>klessly1 sp>k+ at ! bru%es may be tak5 z a sign t some?+ is radically wrong4 ,! pressure ex]t$ by ! spr+ 9 ! bru% hold] may n hold ! bru% firmly aga9/ ! commutator4 ,if bru%es are burn$ or brok5 s t !y d n make good contact on ! commutator1 !y %\ld be r5ew$ or %\ld be s&pap]$ to fit ! commutator4 ,a dirty commutator w cause sp>k+4 ,a commutator hav+ unev5 surface w cause sp>k+1 & %\ld be poli%$ (f or turn$ d[n4 ,illu/ration3 ,fig4 #ajj4 ,sometimes ! mica segm5ts betwe5 commutator b>s d n we> z fa/ z ! b>s & :5 ?is is ! case1 ! bru%es w be kept f mak+ good contact :5 ! commutator b>s are slightly worn4 ,! rem$y is to take ! armature into ! %op1 & groove out ! mica betwe5 ! commutator b>s = a dep? ( ab\t -in* bel[ ! commutator surface4 ,a gre5i% fla% :i* appe>s to run ar\nd ! commutator1 accompani$ by scor+ or burn+ ( ! commutator at two po9ts1 indicates t !re is an op5-circuit$ coil at ! po9ts at :i* ! scor+ occurs z 9 ,fig4 #ajj4 ,! magnetic field may be weak5$ by a %ort circuit 9 ! field coils1 z be=e expla9$1 & ?is may give rise to sp>k+4 ,%ort circuits 9 ! armature may give rise to sp>k+1 b w also be made evid5t by ! j]k+ motion ( ! c> & ! bl[+ out ( ! fuse4 ,failure ( ,c> to ,/>t4 ,! failure ( ! c> to />t :5 ! controll] is turn$ on may be due to any ( ! foll[+ causes3 ,op5+ ( ! circuit break] at ! p[] h\se4 ,poor contact betwe5 ! :eels & ! rails ow+ to dirt or to a break+ ( ! bond wire connections betwe5 ! rail on :i* ! c> is /&+ & ! adjac5t track4 ,"o controll] may be defective 9 t "o ( ! contact f+]s may n make connection ) ! drum4 ,9 ?is case try ! o!r controll] if !re is ano!r "o on ! c>4 ,! fuse may be bl[n or ! circuit break] op5$4 ,! occurr5ce ( ei!r ( ^!1 h[ev]1 is usually accompani$ by a report :i* leaves little d\bt z to ! cause ( ! int]ruption 9 curr5t4 ,! lamp circuit is always at h& = te/+ ! pres5ce ( curr5t on ! trolley wire or ?ird rail4 ,if ! lamps light :5 ! lamp circuit is turn$ on1 x is a tol]ably sure sign t any defect is some:]e 9 ! controll]s1 motors1 or fuse boxes1 al?\gh 9 case ! c>s are on a v dirty rail en\gh curr5t might leak ?r\gh ! dirt to light ! lamps1 b n suffici5t to op]ate ! c>s4 ,9 su* a case1 ! lamps w imm$iately g out z soon z ! controll] is turn$ on4 ,ice on ! trolley wire or ?ird rail w h ! same effect z dirt on ! tracks4 ,,locat+ ,,defects ,,9 ,,motor ,,& ,,controll] ,,wir+4 ,defects 9 ! wir+s are ^? due to 7#a7 op5 circuits1 7#b7 %ort circuits4 ,op5 circuits make !mselves evid5t by no fl[ ( curr5t1 %ort circuits usually by a bl[+ ( ! fuse or op5+ ( ! break]4 ,! po9t ( ! %ort circuit or 8gr\nd0 c be locat$ r\ghly by not+ on :at po9t ! fuse is bl[n4 ,accurate location c be made by cutt+ out ! motors1 disconnect+1 etc41 accord+ to directions 9 ! foll[+ pages4 ,! te/s outl9$ apply p>ticul>ly to ! ,k type ( controll] ) two-motor equipm5t4 ,,op5-,,circuit ,,te/s4 ,no curr5t3 ,on #a/ po9t1 ,op5 circuit b n locat$4 ,on #a/ po9t multiple1 ,motors mo/ probably ,o4 ,k4 ,on s]ies-resi/ance po9ts aft] try+ #a/ po9t multiple1 ,op5 circuit outside controll] & equipm5t wir+4 ,) an op5 any:]e betwe5 trolley & gr\nd no curr5t w fl[ on ! fir/ po9t4 ,op5s are mo/ likely to occur 9 ! motors & ^! may be te/$ fir/4 ,h[ev]1 z w be expla9$ lat]1 "o op5 9 an armature w n /op ! curr5t4 ,to te/ ! motors op5 ! break] & put ! controll] on ! fir/ po9t multiple4 ,!n fla% ! break] quickly4 ,curr5t fl[+ indicates t "o or ! o!r ( ! motors has an op5 circuit4 ,9 ! s]ies position ?is op5 prev5t$ ! fl[ b 9 multiple ! curr5t fl[s ?r\gh ! o!r motor4 ,:i* "o is at fault c be quickly det]m9$ by return+ ! controll] to ! (f position & cutt+ out "o or ! o!r ( ! motors by means ( ! cut-out swit* & !n try+ = curr5t4 ,! c> c 9 any ev5t be run on ! rema9+ motor4 ,on return+ to ! %op ! op5 c be det]m9$ def9itely by ! use ( ! lamp bank4 ,b %\ld no curr5t fl[ :5 ! break] is fla%$ on ! #f? po9t x is reasonable to presume t ! motors are ,o4 ,k4 & t ! op5 is else:]e4 ,! gr\nd = su* a supposition is t z !re is a pa? ?r\gh ea* motor normally1 !re w\ld necess>ily be an op5 9 ea* "o to /op ! curr5t4 ,x is h>dly probable t su* a co9cid5ce w\ld occur4 ,aft] failure to f9d fault ) ! motors1 d\bt z to ! resi/ance may be remov$4 ,! controll] %\ld be plac$ on progressive s]ies-resi/ance po9ts & ! break] fla%$ on ea* "o4 ,if curr5t is obta9$ on any po9t1 ! op5 is 9 ! resi/ance or ! resi/ance lead j beh9d ! "o be+ us$4 ,special c>e %\ld be us$ to fla% ! break] quickly = o!rwise ! fuse may be bl[n4 ,! te/s indicat$ are suffici5t = ! motors1 controll]s & resi/ance wir+4 ,if no curr5t is obta9$ on ei!r ( !m1 ! tr\ble is evid5tly caus$ by a bad rail contact1 gr\nd wire (f if bo? motors are gr\nd$ ?r\gh ! same wire1 an op5 9 ! bl[-out coil1 at ! lightn+ arre/]1 circuit break] or on top ( ! c>4 ,none ( ! te/s appli$ locate ! op5 def9itely1 b ?is c easily be done 9 ! %op or :]ev] a lamp bank is at h&4 ,connect "o t]m9al ( ! lamp bank to ! trolley j beh9d ! circuit break] & ! controll] on ! #a/ po9t s]ies1 !n ) ! o!r t]m9al beg9 at gr\nd & trace backw>ds up ! circuit until ! lamps fail to light4 ,! pa? 9 a ,k type ( controll] is readily trac$ ) ! help ( ,fig4 #bb4 ,,%ort-,,circuit ,,te/s4 ,! location ( %ort-circuits is mu* m t$i\s4 ,! bl[+ ( ! fuse or op5+ ( ! break] w locate !m z %[n bel[4 ,! sep>ate te/s c !n be foll[$ until location is def9ite4 ,^! te/s x mu/ be kept 9 m9d are m especially adapt$ to cases on ! road or :]e no facilities = te/+ are at h&4 ,r ?an bl[ fuses z frequ5tly z indicat$ x w\ld 9 mo/ cases be bett] to place a lamp bank across ! op5 circuit break] & note ! fl[ ( ! curr5t by ! lights4 ,fuse ,bl[s3 ,i4 ,:5 ov]head is ?r[n on may be due to3 #a4 ,gr\nd$ controll] bl[-out coil4 #b4 ,gr\nd$ trolley wire or cable4 #c4 ,gr\nd$ lightn+ arre/]4 ,,ii4 ,on fir/ po9t3 #a4 ,gr\nd$ resi/ance ne> ,r #a4 #b4 ,gr\nd$ controll] cyl9d]4 #c4 ,bridg+ betwe5 ! insulat$ sections ( cyl9d]4 ,,iii4 ,ne> la/ po9t s]ies3 #a4 ,gr\nd$ resi/ance ne> ,r #c1 ,r #d & ,r #e4 #b4 ,no4 #a motor gr\nd$4 ,,iv4 ,ne> la/ po9t multiple3 #a4 ,no4 #b motor gr\nd$4 #b4 ,bridg+ betwe5 l[] sections ( cyl9d]4 #c4 ,armature defective4 ,,case ,i4 ,fuse ,bl[s :5 ov]head is ?r[n on3 #a4 ,gr\nd$ controll] bl[-out coil4 #b4 ,gr\nd$ trolley wire or cable4 #c4 ,gr\nd$ lightn+ arre/]4 ,! bl[+ ( ! fuse imm$iately on clos+ ! ov]head swit* or circuit break]1 :5 ! controll] is on ! (f position1 indicates t ! fault exi/s some:]e betwe5 ! ov]head & ! upp] or trolley f+] ( ! controll]4 ,%\ld ! defect occur dur+ a ?und]/orm1 x may be presum$ at once t lightn+ has gr\nd$ ! bl[-out coil ( ! controll]4 ,,case ,,ii4 ,fuse ,bl[s on fir/ po9t3 #a4 ,gr\nd$ resi/ance ne> ,r #a4 #b4 ,gr\nd$ controll] cyl9d]4 #c4 ,bridg+ betwe5 sections ( cyl9d]4 ,:5 ! controll] is on ! fir/ po9t all ( ! wir+ ( ! sy/em ) ! exception ( ! gr\nd wire = ,no4 #a motor is connect$ ) trolley4 ,b a defect 9 ! wir+ beyond ! resi/ance w n %[ itself on ! fir/ po9t by an abnormal ru% ( curr5t because ! resi/ance ( ! rheo/ats is suffici5t to prev5t any excessive fl[ ( curr5t4 ,illu/ration3 ,fig4 #aja4 ,illu/ration3 ,fig4 #ajb4 ,! resi/ance & leads & ! controll] cyl9d] are ! only p>ts to be te/$ :5 ! fuse bl[s on ! #a/ po9t4 ,,case ,,iii4 ,fuse ,bl[s on #crd or #d? po9t3 #a4 ,gr\nd$ resi/ance ne> ,r #d or ,r #e4 #b4 ,no4 #a motor gr\nd$4 ,) ei!r ( ! above defects ! c> w mo/ probably refuse to move z ! curr5t is l$ to gr\nd be=e pass+ ?r\gh ! motors4 ,illu/ration3 ,fig4 #ajc4 ,plan ( ,c> ,%op4 ,no4 #a motor may be te/$ by cutt+ x out ( s]vice by means ( its cut-out swit*4 ,if ?is removes ! gr\nd1 ! motor is at fault4 ,,case ,,iv4 ,fuse ,bl[s ne> la/ po9t multiple3 #a4 ,no4 #b motor gr\nd$4 #b4 ,ei!r armature %ort-circuit$4 ,! fact t ! fuse did n bl[ on ! s]ies positions excludes ! resi/ances & ,no4 #a motor f inve/igations = gr\nds4 ,cut out bo? motors4 ,if ! gr\nd /ill exi/s ! controll] is defective4 ,if n1 ! fault may be locat$ 9 ei!r "o ( ! motors by cutt+ out fir/ "o & !n ! o!r4 ,,armature ,,te/s ,,= ,,gr\nds4 ,) a lamp bank at h& te/s = gr\nd$ armature c be made z foll[s3 ,?r[ ! rev]se on c5t]4 ,atta* "o t]m9al ( ! lamp bank to ! trolley4 ,put ! o!r t]m9al on ! commutator ( ! armature to be te/$4 ,no curr5t %[s ! armature ,o4 ,k4 ,if curr5t fl[s remove bru%es & try aga91 to be c]ta9 t ! gr\nd is n 9 ! leads4 ,,field ,,te/s ,,= ,,gr\nds4 ,disconnect field leads & put te/ po9t ( ! lamp bank on "o side ( ! t]m9als4 ,no curr5t indicates t ! fields are ,o4 ,k4 ,,rev]s$ ,,fields4 ,9 plac+ new fields 9 ! %ell x (t5 happ5s t "o or m are wrongly connect$4 ,rev]s$ fields make !mselves kn[n by excessive sp>k+ at ! bru%es 9 ea* case4 ,9 ,fig4 #aja all ( ! fields are connect$ correctly4 ,! fl[ ( magnetism is 9 "o pole & out ( ! adjac5t "o4 ,"s ( ! magnetism leaks out ( ! %ell & affects a compass held ne> ! outside4 ,! direction tak5 by ! compass ne$le 9 ! diff]5t positions is %[n4 ,! ne$le %\ld po9t 9 opposite directions ov] adjac5t coils & %\ld lie p>allel to ! %ell 9 positions half way betwe5 two coils4 ,figure #ajb %[s ! fl[ ( magnetism :5 "o field is rev]s$4 ,9 su* a case ! compass w take ! position %[n4 ,! field m>k$ 8,x0 is ! "o rev]s$4 ,) "o rev]s$ field a ma*9e w usually op]ate1 z ! magnetism 9 ?ree ( ! poles is 9 ! normal direction4 ,b an excessive fl[ ( curr5t t has no effect 9 turn+ ! armature w take place on t side ( ! armature next to ! rev]s$ field4 ,,c> ,,repair ,,%ops4 ,e electric railway sy/em has a repair %op 9 :i* ! c>s are ov]haul$4 ,h>dly two %ops are built alike4 ,9 ^? %ops :]e only a few c>s are c>$ =1 ! "w is sometimes all done 9 "o room4 ,! %op plan %[n 9 ,fig4 #ajc 0 pres5t$ to ! ,am]ican ,railway ,me*anical & ,electrical ,association by ,w4 ,d4 ,wright4 ,x conta9s ! idea ^u :i* ! l>g] %ops are n[ be+ con/ruct$1 hav+ a transf] table betwe5 ! sep>ate dep>tm5ts on ei!r side4 ,9 ! g5]al design ( %ops ! blacksmi? %op1 ma*9e %op & truck %op or equipp+ %op %\ld be close toge!r z a great deal ( heavy mat]ial is c>ri$ betwe5 ^! dep>tm5ts4 ,! pa9t %op %\ld be sep>at$ z mu* z possible f ! o!r dep>tm5ts 9 ord] t fly+ du/ & dirt be avoid$4 ,! wood %op may occupy a position at a consid]able di/ance f ! o!r dep>tm5ts z no heavy mat]ial is c>ri$ f ?is %op to !m4 ,! tracks ( ! motor & truck repair %op are usually provid$ ) pits s t trucks & electrical equipm5t may be repair$ & inspect$ f bel[4 ,! tracks 9 %ops are usually ab\t #ae or #af feet betwe5 c5t]s4 ,?is gives a cle>ance ( ab\t #f or #h feet betwe5 c>s :5 adjac5t tracks are occupi$4 ,a l>ge portion ( ! "w done 9 ! av]age %op consi/s ( ! repair+ ( trucks & ! motors m\nt$ on !m4 ,) ! small] c>1 especially ^? ) s+le trucks1 mu* ( ?is "w is done f ! pit bel[ :ile ! trucks are 9 position "u ! c>s4 ,9 ?is case ! armatures are ei!r remov$ by lett+ !m d[n ) ! l[] half ( ! motor %ell by means ( a pit jack1 or ! l[] half ( ! armature %ell is swung d[n by ! use ( a *a9 & block plac$ 9 ! c> & ! armature roll$ out on a bo>d4 ,! trucks ( d\ble truck c>s are usually tak5 out f "u ! c> body :5 repairs are to be made4 ,9 ?is case ! motor leads1 ! s& box connections & ! brake rigg+ are disconnect$ & ! c> body ei!r rais$ or ! trucks l[]$ f x4 ,sev]al me?ods ( rais+ ! c> body are 9 use4 ,:]e no special app>atus is at h&1 ?is is done by means ( jacks1 hydraulic or me*anical1 plac$ "u ! side sills ( ! c> ne> ! end to be rais$4 ,sometimes an ov]head crane is employ$ to lift ! c> body4 ,a special app>atus to raise ! body is employ$ by ! ,/4 ,l\is ,transit ,company4 ,?is consi/s ( f\r screw jacks locat$ bel[ ! floor ( ! %op4 ,an ,i-beam ext5ds ov] ! tops ( ! two locat$ on ! same side ( ! c>4 ,! jacks are motor driv5 by means ( "o sprocket *a9 s t !y rise at ! same spe$4 ,:5 a c> is to be rais$ x is run on ! track betwe5 ! jacks1 b>s are plac$ "u ! c> re/+ across ! ,i-beams & ! jacks raise ! c> (f ! trucks4 ,! trucks are !n roll$ out f "u ! c> & ! repairs made4 ,sometimes1 z has be5 /at$1 ! trucks are dropp$ f ! c> body4 ,9 ?is case ! c> is s plac$ t ! truck re/s on an elevator or section ( track t drops to ! floor bel[4 ,aft] ! c> is block$ up ! trucks are dropp$ & ! repairs made4 ,?is me?od is also us$ 9 *ang+ :eels 9 small %ops4 ,! old pair ( :eels is dropp$ by a h&-op]at$ drop section ( track4 ,a new pair is !n elevat$ into position4 ,?is saves jack+ up "o end ( ! c>4 ,illu/ration3 ,,"o ,,( ,,! ,,s+le-,,phase ,,locomotives ,,on ,,! ,,new ,,york1 ,,new ,,hav5 ,,h>t=d ,,railroad ,,co4 ,note ! two pantograph b[ trolleys = collect+ ! curr5t4 ,,! ,,s+le-,,phase ,,electric ,,railway4 ,9 no o!r l9e ( electrical activity h developm5ts dur+ ! la/ few ye>s be5 s rapid z 9 t ( electric railway "w1 & f all indications ! limit has n yet be5 rea*$4 ,until rec5t ye>s all electric traction has be5 dep5d5t ^u direct curr5t z a motive p[]4 ,?is is due pr9cipally to ! fact t ! s]ies direct-curr5t motor is admirably adapt$ = su* "w1 & no alt]nat+-curr5t motor _h be5 develop$ :i* c\ld be sub/itut$ = x4 ,"o ( ! great advantages possess$ by ! direct-curr5t s]ies motor is its l>ge />t+ torque1 :i* may be sev]al times great] ?an t requir$ to propel a c> at full spe$4 ,?is type ( motor is also ess5tially a v>iable spe$ ma*9e1 & l5ds itself v well to wide v>iations 9 spe$ control2 consequ5tly1 = _m ye>s1 9 ?is c\ntry at lea/1 all advance 0 made along direct-curr5t l9es4 ,! trolley voltage us$ at fir/ 0 f #dej to #ejj volts1 ?is be+ suppli$ directly to ! c>s by means ( a trolley wire1 ! rails be+ us$ = ! return circuit4 ,x is evid5t f ! outset t ! comp>atively l[ voltage1 necessitat+ z x did a correspond+ly l>ge curr5t = a giv5 am\nt ( p[]1 w\ld place a def9ite limitation on ! use ( su* a sy/em = any?+ o!r ?an purely local di/ribution4 ,to ov]come ?is difficulty z f> z possible1 ! trolley voltage 0 gradually rais$ to #fjj or #fej4 ,?is ( c\rse decreas$ ! requir$ curr5t1 ?us increas+ ! scope ( ! sy/em accord+ly4 ,! limit ( increase ( direct-curr5t voltage on ! trolley 0 rea*$ at ab\t ?is po9t1 & ! fact 0 recogniz$ t "s means mu/ be devis$ = us+ a /ill high] voltage1 s9ce !re are difficulties to increas+ ! trolley voltage beyond #fjj or #gjj1 due to fla%+ ( ! motors1 :i* seems to increase directly ) ! voltage4 ,x may be m5tion$ 9 pass+ t "o prom95t electric traction exp]t has /at$ t a direct-curr5t trolley voltage ( #aejj c be us$1 b x rema9s to be prov5 :e!r or n he is correct4 ,a v satisfactory solution ( ! problem = l>ge city /reet railway sy/ems & long int]urban roads1 consi/s 9 ! use ( a comb9ation alt]nat+-curr5t direct-curr5t sy/em 9 :i* ?ree-phase high t5sion alt]nat+ curr5t is g5]at$ & di/ribut$ on high t5sion l9es to sub/ations along ! road4 ,x is "h /epp$ d[n by means ( trans=m]s1 & !n *ang$ to direct curr5t by rot>y conv]t]s1 & suppli$ to ! trolley wire z direct curr5t at ! usual voltage ( say #fjj4 ,?is sy/em has _m advantages1 z !re is b small loss 9 ! high-t5sion l9es1 & ^! l9es c be made comp>atively small1 ?us effect+ a consid]able sav+ 9 inve/m5t = copp]4 ,! above m5tion$ sy/em ( di/ribution is v g5]ally us$1 & has be5 f\nd q satisfactory4 ,! sub/ations c be locat$ at frequ5t int]vals1 & ! di/ance t ! #fjj-volt curr5t mu/ be conduct$ to supply ! c>s is n great4 ,by ?is means curr5t c be di/ribut$ ov] wide areas ) a small loss1 :]e x w\ld be impossible to use ! /raight direct-curr5t sy/em ( di/ribution4 ,:ile1 z /at$1 ?is furni%es a fairly satisfactory solution ( ! problem1 x is f> f p]fect1 z x necessitates ! int]v5tion ( ! rot>y conv]t] sub/ation1 9 :i* ! inve/m5t mu/ be l>ge2 & moreov] ! co/ ( op]ation is high1 z su* a /ation requires skill$ att5dance on acc\nt ( ! some:at intricate nature ( ! rot>y conv]t]4 ,! ideal sy/em1 !re=e1 is "o :i* does away altoge!r ) ! use ( direct curr5t1 ! p[] be+ g5]at$1 di/ribut$1 & utiliz$ by ! motors1 z alt]nat+ curr5t4 ,?ree-phase induction motors h be5 us$ q ext5sively & ) consid]able success 9 ,europe = _m ye>s pa/4 ,! ?ree-phase motor1 h[ev]1 is n entirely adapt$ = railway "w1 s9ce x possesses ! *>act]i/ics ( ! %unt r ?an ( ! s]ies motor1 be+ a con/ant spe$1 n a v>iable spe$ ma*9e4 ,moreov]1 two trolley wires are necess>y in/ead ( "o1 & /ill ano!r disadvantage consi/s 9 ! l[ p[]-factor ( ! ?ree-phase induction motor at />t+4 ,! rec5t application ( ! s+le-phase alt]nat+ curr5t to railway "w has op5$ up a new field1 :i* bids fair to supplant all o!r =ms ( di/ribution to a great ext5t at lea/1 & x is impossible to pr$ict at ! pres5t "t j :at its limitations may or may n prove to be4 ,?is has be5 made possible by ! developm5t ( a practical comm]cial s+le-phase motor1 :i* p]mits ( ! use ( alt]nat+ curr5t on ! trolley wire ) all its advantages1 & yet sacrifices few1 if any1 ( ! advantages ( ! direct-curr5t s]ies motor on ! c>4 ,illu/ration3 ,,int]ior ,,( ,,sub-,,/ation ,,%[+ ,,rot>y ,,conv]t] ,,& ,,trans=m]s4 ,! ?ree-phase curr5t is deliv]$ to ! trans=m]s :]e x is /epp$ d[n to ! voltage requir$ = ! rot>y conv]t]4 ,9 ?is ma*9e x is trans=m$ to direct curr5t & deliv]$ to ! trolley wire4 ,?is motor1 :i* is ! late/ & mo/ important developm5t 9 ! electric railway field1 is ( ! s]ies commutator type1 & does n diff] 9 pr9ciple f its direct-curr5t contempor>y4 ,x is call$ ! commutator type s+le-phase motor1 & is ! "o type ( alt]nat+-curr5t motor :i* has ! same desirable *>act]i/ics = railway "w z ! direct-curr5t s]ies motor4 ,illu/ration3 ,comp5sat+ ,alt]nat+-,curr5t ,railway ,motor4 ,at fir/ ?\ght x may seem /range t a motor built fundam5tally on ! same l9es z a direct-curr5t ma*9e w\ld op]ate on an alt]nat+ curr5t1 z x might appe> t ! motor w\ld t5d to turn fir/ 9 "o direction & !n 9 ! opposite direction ) no resultant motion4 ,?is1 h[ev]1 is n ! case1 because ! direction ( rotation ( a motor dep5ds ^u ! relative direction ( its field & armature curr5ts4 ,if n[ ! field 7 ma9ta9$ 9 a con/ant direction & ! armature suppli$ ) alt]nat+ curr5t1 !n ! t5d5cy w\ld be to rotate fir/ 9 "o direction & !n 9 ! o!r1 x is true1 b z a matt] ( fact ! alt]nat+ curr5t is suppli$ to ! field 9 s]ies ) ! armature1 s t :5 ! direction ( curr5t 9 ! armature *anges x also rev]ses 9 ! field4 ,! result is t ! relative direction ( curr5t 9 ! field & armature is con/ant & ! motor has1 !re=e1 a t5d5cy to turn cont9u\sly 9 "o direction z long z ! alt]nat+-curr5t p[] is suppli$4 ,?is be+ true1 ! "q may arise z to :y ! s+le-phase motor 0 n br\ght to ! front = railway "w long ago4 ,! answ] is t !re 7 c]ta9 inh]5t difficulties to be ov]come1 & ! developm5t ( ! s+le-phase motor has be5 simply ! removal ( ^! difficulties1 r ?an ! design ( an entirely new type ( ma*9e4 ,! mo/ s]i\s ob/acle to ov]come is ! sp>k+ at ! commutator1 due to ! fact t :5 ! t]m9als ( a coil are bridg$ by a bru%1 ! coil acts l ! %ort circuit$ second>y ( a trans=m] ( :i* ! field w9d+ con/itutes ! prim>y4 ,also !re is an iron loss due to ! alt]nat+ magnetic flux ?r\gh ! magnetic circuit2 :ile ano!r objectionable feature is ! c\nt] ,e4,m4,f4 induc$ 9 ! field coils4 ,illu/ration3 ,alt]nat+-,curr5t ,railway ,motor ,field4 ,9 ord] t x may ov]come ^! difficulties1 to "s ext5t1 at lea/1 ! s+le-phase motor pres5ts c]ta9 modifications f ! direct-curr5t type1 9 t x has m field poles1 & ! entire magnetic circuit ( field frame1 cores1 & pole pieces1 is c>efully lam9at$4 ,! numb] ( commutator segm5ts is also increas$1 ?us r$uc+ ! numb] ( armature turns p] coil1 & !re are special features introduc$ to prev5t sp>k+1 su* z comp5sat+ w9d+s :i* neutralize ! effect ( armature di/ortion2 ! use ( n>r[ bru%es2 a type ( armature w9d+ :i* gives a l[ reactance p] coil2 ! use ( high resi/ance leads betwe5 ! armature coils & commutator segm5ts1 etc4 ,! s+le-phase motor is !n a ref9$ & highly p]fect$ type ( direct-curr5t motor1 & ?is expla9s ! fact t x w op]ate on ei!r alt]nat+- or direct-curr5t circuits4 ,9 fact "s claim t x w op]ate ev5 m effici5tly on direct curr5t ?an ! regulation direct-curr5t motor itself4 ,illu/ration3 ,s+le-,phase ,armature1 ,unm\nt$4 ,! field = :i* ! s+le-phase motor seems p>ticul>ly adapt$ is t ( heavy s]vice & int]urban "w1 :]e x has _m di/9ct advantages1 among :i* may be m5tion$ ! foll[+3 ,! alt]nat+ curr5t on ! trolley all[s ! use ( a high voltage & correspond+ly small] curr5t1 :i* r$uces ! l9e loss & p]mits ( ! use ( small] wire1 :i* ( c\rse means a sav+ 9 ! inve/m5t = copp]4 ,moreov]1 ! difficulty ( collect+ a l>ge curr5t f ! trolley wire is ov]come4 ,rot>y conv]t] sub/ations are elim9at$1 be+ replac$ by simple & *eap trans=m] sub/ations1 :i* require no att5dance4 ,! capacity c be easily increas$ by m]ely increas+ ! numb] ( ^! trans=m] sub/ations4 ,! effici5cy ( spe$ control is a po9t p>ticul>ly wor?y ( m5tion4 ,9 direct-curr5t spe$ control1 ! s]ies-p>allel me?od is us$ almo/ exclusively4 ,?is consi/s ( putt+ ! motors 9 s]ies = l[ spe$ & 9 p>allel = high spe$4 ,?is p]mits ( two1 & only two1 economical runn+ po9ts2 ! "o at full spe$1 & ! o!r at approximately half spe$4 ,all int]m$iate po9ts mu/ be obta9$ by ! ins]tion ( dead resi/ance 9 :i* ! voltage is simply wa/$ z heat1 ?us caus+ a l>ge loss p>ticul>ly at />t+4 ,) ! s+le-phase motor ! curr5t is suppli$ to ! c> ) a voltage ( say #ccjj4 ,x is !n /epp$ d[n by means ( trans=m]s on ! c> to ! voltage ( ! motors1 :i* may be #bjj or #bej volts4 ,! spe$ is1 ( c\rse1 dep5d5t ^u ! voltage appli$ to ! motors1 & ?is voltage is cut d[n f ! maximum1 to obta9 v>i\s gradations1 by means ( an induction controll]1 or by taps f an auto-trans=m]4 ,?us ! motor takes f ! trolley only slightly m p[] ?an is actually requir$ to op]ate x at any giv5 spe$1 in/ead ( tak+ full voltage f ! l9e & absorb+ "p ( x 9 dead resi/ance4 ,illu/ration3 ,auto ,trans=m]4 ,! effect ( electrolysis ^u neighbor+ wat] pipes p>allel+ an electric road1 :i* is ! cause ( s mu* tr\ble ) direct curr5t1 is entirely elim9at$1 z electrolysis evid5tly w n take place ) alt]nat+ curr5t4 ,9 connection ) ?is sy/em a slid+ contact device or b[ trolley has 9 _m cases be5 sub/itut$ ) consid]able success = ! ord9>y curr5t collect+ device1 or trolley :eel1 "o advantage ( ?is be+ t ! c> c be run 9 ei!r direction )\t rev]s+ ! contact device4 ,ano!r v satisfactory =m ( trolley is ( ! pantograph type ) slid+ %oe1 %[n on ! ,new ,york1 ,new ,hav5 & ,h>t=d locomotive4 ,a new =m ( trolley susp5sion kn[n z ! cat5>y has be5 develop$ to meet ! dem& = m sub/antial con/ruction necessitat$ by ! high trolley voltage4 ,?is consi/s ( a /r&$ galvaniz$ /eel mess5g] or support+ cable1 f :i* ! trolley wire is susp5d$ at int]vals ( ab\t #aj feet1 ?us keep+ x at a uni=m di/ance above ! track4 ,illu/ration3 ,ma/] ,controll] ,us$ 9 ,connection ) ! ,multiple-,unit ,sy/em z ,appli$ to ,s+le-,phase ,"w4 ,! multiple-unit sy/em ( control c be us$ 9 connection ) s+le-phase motors1 ?is be+ ! s*eme :i* has be5 9 use = a long "t on elevat$ & o!r roads us+ direct curr5t1 :]eby sev]al c>s c be op]at$ 9 a tra9 f a s+le po9t1 ea* c> be+ equipp$ ) its individual motor & controll+ app>atus4 ,! entire sy/em is !n controll$ z "o unit by a s+le motorman /ation$ usually 9 ! front ( ! fir/ c>4 ,?is me?od ( control has become ( su* trem5d\s importance t any sy/em to :i* x _c be appli$ w\ld be s]i\sly h&icapp$4 ,c>s equipp$ ) s+le-phase motors c be op]at$ on ei!r direct-curr5t or alt]nat+-curr5t l9es1 ) high or l[ t5sion1 ) trolley or ?ird rail4 ,x mu/ n be suppos$1 h[ev]1 t ) all ! above m5tion$ advantages1 ! s+le-phase sy/em has no disadvantages1 z su* is n ! case4 ,! c> equipm5t1 due to ! trans=m]s & ! nature ( ! motors1 is consid]ably heavi]4 ,! motors !mselves are m exp5sive on acc\nt ( _! special con/ruction4 ,! equipm5t is n always adapt$ = op]ation on exi/+ l9es4 ,!re is a slight increas$ 8app>5t0 resi/ance ( ! trolley l9e & a consid]able increas$ 8app>5t0 resi/ance ( ! rails1 due to reactance caus$ by ! alt]nat+ nature ( ! curr5t4 ,!re is also an active electro-motive =ce betwe5 ! field coils1 :i* is objectionable1 & !re is a possibility ( int]f]5ce ) neighbor+ telephone l9es4 ,fur!rmore1 !re is slight loss 9 p[] 9 ! trans=m]s on ! c>1 :ile ! p[]-factor ( ! motors is less ?an unity4 ,summ+ ! matt] up z a :ole1 h[ev]1 ! advantages seem to ov]balance ! disadvantages1 at lea/ = _m k9ds ( "w1 & x is safe to pr$ict t ?is new sy/em ( op]ation w h a v wide & increas+ application 9 ! ne> future4 ,z to ! op]ation ( ! sy/em 9 g5]al1 ! curr5t may be develop$ by s+le-phase1 two-phase1 or ?ree-phase g5]ators1 & suppli$ to ! trans=m] sub/ations j z x 0 =m]ly suppli$ to ! rot>y conv]t] sub/ations4 ,only a s+le phase is us$ on any section ( ! trolley l9e4 ,! voltage on ?is transmission l9e w dep5d ^u ! exi/+ conditions1 & c be figur$ out l any o!r problem 9 p[] transmission4 ,illu/ration3 ,truck ,complete ) ,s+le-,phase ,motors & ,contact ,%oes4 ,?ree-phase g5]ators w\ld ord9>ily be us$1 z less copp] is requir$ to supply a giv5 am\nt ( p[]4 ,! common frequ5cy is #be cycles p] second4 ,at ! trans=m] /ations1 ! voltage is !n /epp$ d[n to t requir$ on ! trolley1 :i* may be #b1jjj1 #c1cjj1 #f1fjj1 or ev5 #aa1jjj volts4 ,:ile we _c speak yet ( a /&>d voltage1 #ccjj seems to be f9d+ consid]able favor4 ,! voltage = :i* ! motors are w\nd is #bjj or #bej1 ! ,g5]al ,electric motors us+ ! =m] voltage1 & ! ,we/+h\se ! latt]4 ,:5 op]at+ on alt]nat+ curr5t ! motors are connect$ 9 p>allel1 & :5 runn+ on direct curr5t !y are connect$ 9 s]ies4 ,motors h be5 con/ruct$ f #ej to #bbe horsep[]1 & !re is no app>5t reason :y l>g] ones c\ld n be made to op]ate ) equal satisfaction4 ,illu/ration3 ,magnetic ,spe$ ,indicator4 ,among ! roads 9 ?is c\ntry :i* are ei!r us+1 or plann+ to use s+le-phase curr5t1 may be m5tion$ ! ,ball/on-,s*5ectady l9e1 :i* 0 "o ( ! fir/ sy/ems to be equipp$ & has be5 9 successful op]ation = "s "t4 ,?is road uses ! alt]nat+-curr5t motor develop$ by ! ,g5]al ,electric ,co4 ,! motors are adapt$ = op]ation on ! #b1jjj-volt alt]nat+-curr5t trolley betwe5 cities1 & on ! /&>d #fjj-volt direct curr5t 9 ,s*5ectady4 ,!y are w\nd = #djj volts1 & are op]at$ 9 s]ies on ! #fjj-volt direct curr5t4 ,! frequ5cy us$ is #be cycles4 ,curr5t is suppli$ by an ov]head trolley1 no fe$]s be+ us$4 ,a second road ( importance is "o 9 ,georgia betwe5 ,atlanta & ,m>ietta1 :i* is #ae miles 9 l5g?4 ,?is uses ! ,we/+h\se equipm5t4 ,! curr5t on ! trolley is #b1bjj volts & #be cycles4 ,x is transmitt$ at a voltage ( #bb1jjj4 ,ano!r road ( importance is ! ,indiana & ,c9c9nati int]urban l9e1 #da miles 9 l5g?1 :i* has be5 9 op]ation on regul> s*$ule s9ce ,july #a/1 #aije4 ,= #cg miles ! road is op]at$ f alt]nat+ curr5t1 & = #d miles1 f direct curr5t4 ,f\r #ge-;horse p[] motors p] c> are us$1 capable ( a maximum spe$ ( #fe miles p] h\r4 ,illu/ration3 ,armature ,quill4 ,! ,bloom+ton1 ,pontiac & ,joliet ,electric ,railway is a s+le-phase road equipp$ ) ,g5]al ,electric app>atus1 & has ma9ta9$ a regul> s*$ule ov] a di/ance ( m ?an #aj miles s9ce ,m>*1 #aije4 ,! plans are n[ be+ laid = a s+le-phase road1 :i* w run s\? f ,spokane1 ,wa%+ton1 a di/ance ( #aej miles4 ,! curr5t on ! transmission l9e is #de1jjj volts1 :i* is /epp$ d[n to #f1fjj on ! trolley4 ,! c> w be capable ( op]at+ on curr5t f a #f1fjj-volt alt]nat+1 a #gjj-volt alt]nat+1 or a #ege-volt direct-curr5t supply4 ,p]haps ! mo/ important move :i* has be5 made 9 ! direction ( s+le-phase traction ?us f> is ! decision ( ! ,new ,york1 ,new ,hav51 & ,h>t=d road to e/abli% a long-di/ance pass5g] traffic on ! s+le-phase sy/em4 ,accord+ to ! late/ plans ?is road w op]ate betwe5 ! ,gr& ,c5tral ,depot & ,woodlawn1 ,n4 ,y41 ov] ! t]m9al tracks ( ! ,new ,york ,c5tral road1 on direct curr5t tak5 f ! trolley4 ,f ,woodlawn1 ,n4 ,y41 to ,/am=d1 ,conn41 ! road w be op]at$ on ! s+le-phase sy/em4 ,illu/ration3 ,a ,pair ( ,driv]s ) ,s+le-,phase ,motor ,m\nt$ ^u ,quill4 ,! equipm5t is be+ suppli$ by ! ,we/+h\se ,co4 ,! curr5t is g5]at$ by revolv+-field type turb9e-driv5 alt]nators4 ,! armatures are design$ = ei!r ?ree-phase or s+le-phase connection4 ,! curr5t is g5]at$ at #be cycles & #aa1jjj volts1 be+ deliv]$ directly to ! trolley1 & !nce to ! c>s1 )\t ! int]v5tion ( any trans=m]s4 ,! d\ble cat5>y susp5sion f mess5g] wires is us$ to support ! trolley4 ,! locomotives are ea* equipp$ ) f\r #bjj-;,h4 ,p4 ge>less motors1 design$ to op]ate on #bce-volt alt]nat+ curr5t & #bge- to #cjj-volt direct curr5t4 ,! armature is n m\nt$ on ! %aft direct1 b is built ^u a quill ?r\gh :i* ! axle passes ) ab\t -in* cle>ance all ar\nd4 ,!re is a flange at ea* end ( ! quill f :i* sev5 p9s project & fit into ! hubs ( ! driv+ :eels4 ,on ! direct-curr5t "p ( ! l9e1 curr5t is deliv]$ to ! c> ?r\gh eight collect+ %oes f a ?ird rail4 ,on ! alt]nat+-curr5t section1 curr5t is deliv]$ ?r\gh two pantograph b[ trolleys4 ,on ! direct-curr5t section ! s]ies-p>allel me?od ( spe$ control is us$1 curr5t be+ f$ directly to ! motors :i* are connect$ two 9 s]ies p]man5tly & ! s]ies-p>allel control is appli$ to ! motors 9 gr\ps ( two4 ,! alt]nat+-curr5t spe$ control is accompli%$ by six taps f an auto-trans=m] = ! correspond+ runn+ po9ts4 ,! c>s weigh #gh tons & are capable ( a spe$ ( #fj to #fe miles p] h\r4 ,! electro-pneumatic unit-swit* type ( control is us$4 ,at ea* end ( ! cab is a ma/] controll] f :i* ! ma9 controll] is op]at$4 ,sev]al locomotives c be op]at$ toge!r on ! multiple-unit sy/em1 if desir$4 ,illu/ration3 ,six-,unit ,swit* ,gr\p1 ,s+le-,phase ,sy/em4 ,! ,wa%+ton1 ,baltimore & ,indiana s+le-phase road is ! late/ 9 ! field1 contracts hav+ be5 plac$ v rec5tly4 ,! curr5t w be transmitt$ at #cc1jjj volts & #be cycles1 !n be+ /epp$ d[n to #f1fjj volts on ! trolley4 ,! road w be #fj miles long & w be equipp$ ) ,g5]al ,electric app>atus4 ,f\r #abe-;,h4 ,p4 motors capable ( op]at+ on ei!r alt]nat+ curr5t or direct curr5t w be us$1 & ! c>s w be capable ( a spe$ ( #fj miles p] h\r4 ,,index ,air brakes1 #ef ,air compressors1 #eg automatic gov]nor =1 #eg ,we/+h\se1 #eh ,alt]nat+-curr5t g5]ators1 #aje ,alt]nat+-curr5t swit*bo>ds1 #aaj ,alt]nat+-curr5t sy/ems1 #aac s+le-phase motors1 #aad ?ree-phase motors1 #aac ,alt]nat+-curr5t transmission1 #ii ,armature coils1 #h ,armature leads1 #i ,armature te/s = gr\nds1 #acc ,armature w9d+1 #e defects (1 #abd mi/akes 91 #abf ,automatic gov]nor = air compressors1 #eg ,balla/1 #he ,be>+s ( railway motors1 #ac ,block signals = electric railways1 #id ,bond te/+1 #abj ,bond+ & return circuits1 #hh ,boo/] fe$]1 #ih ,brackets1 #ge ,brake lev]ages & %oe pressure1 #ed ,brake rigg+1 #ec ,brake %oes1 #fd ,bru% hold]s1 #aj ,bru%es1 #aj ,burn-outs1 #abc ,canopy swit*1 #ci ,c>1 failure ( to />t1 #abg ,c> bodies1 #fg ,c> circuit break]1 #ci ,c> con/ruction1 #fg ,c> equipm5t1 #c ,c> heat]s1 #cd electric1 #cd hot-wat]1 #cf ,c> pa9t+1 #gb ,c> repair %ops1 #acd ,c> weights1 #gb ,c> :eels1 #ea ,c> wir+1 #cg ,ca/-weld$ jo9ts1 #hg ,coeffici5t ( friction1 #fe ,common ,t-rail1 #hd ,commutator type s+le-phase motor1 #aci ,compressors1 #eg ,conductivity ( /eel rail1 #hj ,conduit sy/ems1 #ha contact pl[1 #hb co/ (1 #hb curr5t leakage1 #hc ,contact pl[1 #hb ,contact %oes1 #de ,controll] con/ruction1 #ai ,controll] not*es1 #bg ,controll] wir+1 #bj ,controll]s1 #af ,co/ ( p[]1 #aai ,c\pl]s1 #ff ,curr5t requir$ to heat c>s1 #ce ,curr5t leakage1 #hc ,defects ( armature w9d+s1 #abd ,direct-curr5t fe$+1 #ih ,d\ble-curr5t g5]ators1 #aje ,drawb>s1 #ff ,economy 9 p[]1 #aah ,electric c> accessories1 #ci canopy swit*1 #ci c> circuit break]1 #ci contact %oes1 #de fuses1 #da lamp circuits1 #dc lightn+ arre/]s1 #da trolley base1 #dd trolley poles1 #dd trolley h>p1 #de trolley :eels1 #dd ,electric c>s1 road te/s (1 #aag ,electric heat]s = c>s1 #cd ,electric railway1 #a ,electrically weld$ jo9ts1 #hg ,electrolysis1 #ie prev5tion (1 #ig ,fe$] panel1 #aaj ,fe$] sy/ems1 #ib ,fe$]s1 #ge ,field coils1 #h ,field te/s = gr\nds1 #acc ,f\r motors1 #ai ,fuse bl[s1 #acj ,fuses1 #da ,ge>+1 #ab ,g4 ,e4 electric brake1 #fa ,g4 ,e4 tra9 control1 #bi ,g5]ator1 />t+ up1 #ajh ,g5]ator ,d4 ,c4 panels1 #ajf ,g5]ators1 #aje ,gird] rail1 #hc ,gr\nds1 #abc ,high-t5sion l9es1 #gg ,high-t5sion oil swit*es1 #aaa ,highway cross+s1 #hj ,hot-wat] heat]s = c>s1 #cf ,insulators1 ?ird rail1 #gi ,int]urban railway1 sy/em ( di/ribution =1 #aja ,jo9ts = rails1 #hf ,lamp circuits1 #dc ,lightn+ arre/]s1 #da ,locat+ defects 9 motor & controll] wir+1 #abh ,location ( p[] h\ses1 #aja ?ird rail1 #gi ,lubrication ( railway motors1 #ac ,magnetic bl[-out1 #bf ,maximum traction trucks1 #ea ,mom5tum brakes1 #ei ,motor leads1 #i ,motor susp5sion1 #ad ,motor-coil te/+1 #aba ,motors1 #c z em]g5cy brakes1 #fc ( ! ,new ,york ,c5tral electric locomotive1 #ae ,multiple-unit control1 #bi ,oil swit*es1 high t5sion1 #aaa ,op5-circuit te/s1 #abh ,op5+ cases = inspection1 #aj ,ov]head con/ruction1 #gc brackets1 #ge fe$]s1 #ge high-t5sion l9es1 #gg section insulators1 #gf span wires1 #gd trolley wire1 #gc trolley-wire clamps & e>s1 #gc ,pott] ?ird-rail %oe1 #df ,p[] co/ (1 #aai economy 91 #aah tak5 by c>s1 #aae ,p[] h\se location1 #aja ,p[] /ations1 g5]al plan (1 #aje ,p[] supply & di/ribution1 #ih ,railway motors be>+s1 #ac bru%es1 #aj *>act]i/ics (1 #c ge>+ (1 #ab lubrication (1 #ac ,rate ( ret>dation 9 brak+1 #ff ,resi/ance ( track1 #ia ,resi/ances1 #ch ,return fe$]s1 #ib ,rev]sal ( motor1 #bf ,rev]s$ fields1 #acc ,rheo/at control1 #ag ,road te/s ( electric c>s1 #aag ,sectional insulators1 #gf ,s]ies-p>allel control1 #ag ,%anghai ,t-rail1 #hd ,%ort-circuit te/s1 #acj ,s+le trucks1 #dh ,s+le-phase electric railway1 #acf ,s+le-phase motors1 #aad1 #aci ,sleet on trolleys & ?ird rails1 #df ,slid+ & sp9n+ :eels1 #aai ,span wires1 #gd ,sp>k+ at ! commutator1 #abg ,sprague multiple-unit sy/em ( control1 #bi ,/eel c> fram+1 #ga ,/orage air brakes1 #eh ,/orage batt]ies 9 /ations1 #aac ,/reet railway motors1 g5]al data on1 #f ,supplem5t>y return fe$]s1 #ib ,sw+ bol/] trucks1 #di ,swit*bo>ds1 #ajf alt]nat+-curr5t1 #aaj ,swit*es1 ?ird rail1 #gi ,swivel trucks1 #dh ,t-rail1 #hd ,!rmit weld+1 #hh ,?ird rail1 #gi advantages 9 op]ation1 #hj ,?ird rail conductivity (1 #hj co/ (1 #hj highway cross+s1 #hj insulators =1 #gi location1 #gi swit*es1 #gi ,?ree-phase motors1 #aac ,track brakes1 #fc ,track con/ruction1 #hc ,track resi/ance1 #ia ,track s&]s1 #fe ,track support1 #he ,transmission sy/ems1 effici5cy (1 #aja ,trilby groove rail1 #hd ,trolley base1 #dd ,trolley h>p1 #de ,trolley poles1 #dd ,trolley :eels1 #dd ,trolley wire1 #gc ,trolley-wire clamps & c>s1 #gc ,trucks1 #df maximum traction1 #ea s+le1 #dh sw+ bol/]1 #di swivel1 #dh ,type ,l controll]s1 wir+ (1 #bd ,,ann\ncem5t ,,( ,,com+ ,,books ,,practical ,,& ,,sci5tific ,,c>p5try4 ,by ,g4 ,t[ns5d4 #aej pp41 #bbd illus4 ,a work+ manual = ,c>p5t]s & ,woodwork]s 9 g5]al4 ,n a !oretical treatise1 b a practical work+ guide4 ,price1 #a4jj ,,gas ,,eng9es ,,& ,,produc]s4 ,by ,m>ks & ,wv]4 #aej pp41 #ij illus4 ,late/ in=mation 9 ?is rapidly develop+ field4 ,= ,eng9e]s1 ,ma*9i/s1 ,automobili/s4 ,price #a4jj ,,masonry ,,con/ruction4 ,by ,phillips & ,byrne4 #adj pp41 #dd illus4 ,late/ & be/ ,am]ican me?ods4 ,price #a4jj ,,wat] ,,supply4 ,by ,f4 ,e4 ,turneaure4 #aej pp41 #dj illus4 ,an exhau/ive comp5dium = ,sanit>y & ,wat]works ,eng9e]s & all int]e/$ 9 matt]s affect+ public heal?4 ,price #a4jj ,,highway ,,con/ruction4 ,by ,phillips & ,byrne4 #adj pp41 #hj illus4 ,mod]n me?ods = ,road ,build]s & all int]e/$ 9 bett] ways ( communication4 ,price #a4jj ,,re9=c$ ,,concrete4 ,by ,webb & ,gibson4 #aej pp41 #adj illus4 ,a manual ( practical me?ods = ,ar*itects1 ,build]s4 ,contractors1 ,civil & ,sanit>y ,eng9e]s4 ,in=mation = ! fir/ "t made kn[n to ! _w4 ,bas$ on rec5t con/ruction "w1 special te/s1 etc4 ,price #a4jj ,,managem5t ,,( ,,dynamo-,,electric ,,ma*9]y4 ,by ,f4 ,b4 ,crock]4 #acj pp41 #fe illus4 ,= all :o h to d ) electric light or p[] plants4 ,price #a4jj ,,/eam ,,eng9es4 ,by ,lel& & ,sn[4 #agj pp41 #fc illus4 ,a practical guide4 ,field cov]$ 9 a way anyone c grasp4 ,price #a4jj ,,electric ,,railways4 ,by ,j4 ,r4 ,crava?4 #aej pp41 #ajc illus4 ,trolley & ?ird-rail sy/ems4 ,electric ,locomotive1 etc4 ,price #a4jj ,,e/imat+4 ,by ,edw>d ,ni*ols4 #adj pp41 #ce illus4 ,= all work]s 9 ,build+ trades4 ,tells h[ to e/imate intellig5tly4 ,price #a4jj ,,contracts ,,& ,,specifications4 ,by ,james ,c4 ,plant4 #acj pp41 fully illu/rat$4 ,=ms ( public & private contracts1 specifications1 bonds1 etc41 duties & responsibilities ( ,ar*itects1 ,contractors1 & ,own]s4 ,price #a4jj ,,/air-,,build+ ,,& ,,/eel ,,squ>e4 ,by ,hodgson & ,williams4 #acj pp41 #ahj illus4 ,only up-to-date "w on ^! subjects4 ,price #a4jj ,,valve ,,ge>s ,,& ,,indicators4 ,by ,lel& & ,d[4 #aej pp41 #aje illus4 ,two books 9 "o4 ,types ( valves1 ge>s1 etc41 fully expla9$4 ,price #a4jj ,,/r5g? ,,( ,,mat]ials4 ,by ,e4 ,r4 ,maur]4 #adj pp41 #eh illus4 ,= ,ar*itects1 ,build]s1 ,/eel & ,concrete ,work]s4 ,enables "o to avoid mi/akes4 ,price #a4jj ,,! ,,electric ,,telegraph4 ,by ,?om & ,coll9s4 #aej pp41 #ha illus4 ,c>ries along by easy /eps to complete ma/]y4 ,multiplex & ,wireless telegraph expla9$4 ,price #a4jj ,,me*anical ,,draw+4 ,by ,e4 ,k5ison4 #afj pp41 #adj illus4 ,complete c\rse 9 projections1 %ade l9es1 int]sections & developm5ts1 lett]+1 ) ex]cises & plates4 ,price #a4jj ,,p[] ,,/ations ,,& ,,transmission4 ,by ,g4 ,c4 ,%aad4 #afj pp41 #dc illus4 ,= ,electrical ,work]s4 ,up-to-date practice4 ,price #a4jj ,,patt]n ,,mak+4 ,by ,james ,rit*ey4 #aej pp41 #bej illus4 ,= ,wood & ,metal ,work]s & ,mold]s4 ,me?ods ( build+ up & f9i%+1 fully describ$4 ,price #a4jj ,,survey+4 ,by ,alfr$ ,e4 ,phillips4 #bjj pp41 #acc illus4 ,= ,civil ,eng9e]s & ,/ud5ts4 ,all details ( field "w expla9$4 ,price #a4ej ,,/eel ,,con/ruction4 ,by ,e4 ,a4 ,,tuck]4 #cjj pp41 #bge illus4 ,cov]s e phase ( ! use ( /eel 9 /ructural "w4 ,bas$ on actual exp]i5ce1 special te/s1 etc4 ,= ,ar*itects1 ,bridge ,build]s1 ,contractors1 ,civil ,eng9e]s4 ,price #a4ej ,,build+ ,,sup]9t5d5ce4 ,by ,e4 ,ni*ols4 #bjj pp41 #bej illus4 ,co/ly mi/akes occur ?r\gh lack ( att5tion at prop] "t1 hurtful to ,own] & discr$itable to ,ar*itect & ,build]4 ,gives ?or\gh k ( me?ods & mat]ials4 ,price #a4ej ,,ar*itectural ,,draw+ ,,& ,,lett]+4 ,by ,b\rne1 von ,hol/ & ,br[n4 #bjj pp41 #ee draw+s4 ,complete c\rse 9 mak+ work+ draw+s & arti/ic lett]+ = ar*itectural purposes4 ,price #a4ej ,,ma*9e ,,%op ,,"w4 ,by ,f4 ,w4 ,turn]4 #bjj pp41 #bjj illus4 ,meets e requirem5t ( ! %opman1 f ! simple/ tools to ! mo/ complex turn+ & mill+ ma*9es4 ,price #a4ej ,,tool ,,mak+4 ,by ,e4 ,r4 ,m>kham4 #bjj pp41 #cbe illus4 ,h[ to make1 h[ to use tools4 ,pr(usely illu/rat$4 ,price #a4ej ,,ma*9e ,,design4 ,by ,c4 ,l4 ,griff94 #bjj pp41 #hb designs4 ,writt5 by "o ( ! =emo/ au?orities ( ! day4 ,e illu/ration repres5ts a new device 9 ma*9e %op practice4 ,price #a4ej ,^! volumes are h&somely b\nd 9 r$ art ,vellum de ,luxe1 size #f #i in*es4 ,s5t prepaid to any "p ( ! _w1 on receipt ( price4 ,remit by ,draft1 ,po/al ,ord]1 ,express ,ord]1 or ,regi/]$ ,lett]4 ,,am]ican ,,s*ool ,,( ,,correspond5ce1 ,,*icago ,transcrib]'s ,notes3 ,text enclos$ by und]scores is 9 italics 7italics74 ,text enclos$ by equals is 9 bold 7bold74 ,text enclos$ by pluses is 9 small caps 7small caps74 ,obvi\s typographical errors h be5 sil5tly correct$4