}MtiUH)ii»M(» wtmiittffimimMiitnuttK ^ jMMam^ _ii] WM ^^^^^^^■dSH^^^^iuy^i ^^^^^^H ^^B M ^^BtmwtfWiH}}^ ^H UNIVERSITY OF ILLINOIS LIBRARY Class Book Volume My 08-1 5M The person charging this material is re- sponsible for its return on or before the Latest Date stamped below. Theft, mutilation, and underlining of books are reasons for disciplinary action and may result in dismissal from the University. University of Illinois Library OCT 2 1961 ?ftw '>^ RFC* L161— O-1096 .IBRARY '<- THE >f ILUN > O S o u o a: H U u .J a c4 p. a o o Z o . » OQ ^ Z (D o a s ^ CO O o K bl H 2 Electric Railways A Treatise on the ON, INC MODERN DEVELOPMENT OF ELRCTRIC TRACTION, INCLUDING PRACTICAL INSTRUCTION IN THE LATENT 'A!1'T'!>;0VKI) METHODS OF ELECTRIC RAILROAD R y § 55 < a^ z rt - Q o- 9 a 2 Z ■< '-' o OS o a u ♦i o a s^ a 3 z • 2 ^ O o ri Ou, o »5 S Ifl P o o • o 1 t/5 o *i t/5 H M o « u >« H a Q >< > < H » ELECTRIC RAILWAYS, PART I. The general name "electric railway" is applied to all railways employing electric motors to supply power for the propulsion of cars. On all electric railways in commercial use to-day, the electric motor is used to furnish power to the driving wheels of the car or locomotive, the electric motor being the most efficient known means of transform- ing electrical into mechanical energy. Electric railways are usually classified according to the methods by which current is supplied to the moving car. Thus, where an overhead trolley wire is used, as on the great majority of electric rail- ways, the term trolley road is applied. Where an insulated steel rail is laid alongside the track rail for supplying current, as on the "e:e- vated" roads in America and on a few interurban roads, the term third-rail road is used. Where, as on the street railways of a few large cities, the conductors are })laced in a conduit underneath the surface of the street, and current is taken l)y means of a plow or shoe running in the conduit, the name electric-conduit railway is most com- monly applied. There are also a few systems using conductors buried beneath the pavement, and having contact buttons or sections of conductor rail on the street surface, which sections are supplied with current by automatic electromagnetic switching apparatus as the car passes, but which are normally dead and harmless. The over- head trolley and the third-rail systems are by far the most common. A further general classification of electric railways has recently been made because of the introduction of alternating-current railway motors. The great majority of electric railways em{)loy direct- current motors. Wliere alternating-current motors are used, the ro.ad is sp(jkeii of as one using single-phase alternating-current motors or three-phase alternating-current motors, as the case may be. All electric railway systems in commercud use are operated on an approximately constant j)otential ur voltage, and the various electric motor cars operating on tlu> system are c(mnected across ELECTRIC RAILWAYS the lines in parallel. The most coniuion practice is to utilize the rails and ground as one side of the circuit, and the overhead trolley wire or "third rail" as the other siile, as in Fig. 1. The trolley wire or third rail is, of course, thoroughly insulated from the ground. The positive poles of the generators at the j)o\ver house are usually Tro//ey w/re or 3rd ra// I Generator far Power Sraf/on r nnnnn xz TL nnnnnnnn Track niLZ TTTT connected to the trolley wire, and tlie r.egative ]K)les to the rails and ground. The various electric motor cars, heing connected in parallel or multiple between the trolley wire and the ground, draw whatever current is necessary for their operation. Where the conduit system is used, both sides of the circuit are insulated from the ground, and the contact shoe or plow collects current from two conducting rails in the conduit, one of these conducting rails being positive and Fig. 2. ]i:iiUvay Motor. the other negative. A double-trollev svsteni is also in use to a limited extent. In this system, both the positive and the negative sides of the circuit are msulated from the ground, one trolley wire being positive and the other negative. Further discussion of \\w matters just outlined will be taken up in the succeeding pages. ELECTRIC RAILWAYS CAR EQUIPHENT. MOTORS. The voltage most commonly employed by electric railways is 500 to 600; and the motors are 500-volt direct-current series-wound motors, designed especially for railway service. The electric railway motor must he dustproof and waterproof because of the position it occupies under the car. For this reason electric railway motors are made in the form of a steel case (Fig. 2), which entirely surrounds the field-magnet poles and takes the place of the yokes or frames that support the fields on stationary motors. Cast steel is the material now usually employed for railway motor cases and fields, on account Fig. 3. Kailway Motor. Upper Field Kaised. of its mechanical strength and its high magnetic permeability. The four poles project inwardly from the case, as seen in the open motor case, Fig. 3, which is that of a Westinghouse No. G9 motor. Railway motors have usually four poles because this permits :)f a symmetrical and economical arrangement of material around the armature, and hence permits the motor to be placed in the small space available on the car truck. Two-pole motors have been used in the past, but they were not as compact as the foiu'-pole type Characteristics of Railway Motors. The curve sheet, Fig. 4, for the Westinghouse No. 69 motor represents in general the char- acteristics of all direct-current railway motors. The figures for each curve are found with luunes corresponding to the curve to which they apj)ly,at each side represented by vertical ELECTKIC RAILWAYS (listanc'f dh the slieet. The ainjxTes, ivpreseiited bv the horizontal (Hstance, are marked at the bottom, and apply in common to all the cur^'es. The tractive effort at different current consumption is represented l)v a line curvin<; upwards somewhat. I'his shows that the tractive effort increases, in a proportion greater than directly, as the current increases. The tonjue recpiired in starting may be many times greater than that necessary to maintain the car at full speed. The series-wound i ; , ' M Ml 1 WESTINGHOUSE No.69 RAILWAY MOTOR 500 VOLTS GEAR RATIO. 14 TO 68. WHEELS. 33 " CONTINUOUS CAPACITY, 2S AMPERES AT 300 VOLTS, OR 23 AMPERES AT 400 VOLTS. .; u •s •* e a:' J u Ic / f- 210 ■» 3 o / / A ^ ^ -Ji' 7. /. / lao ' EPFiCiENCy 1 1 1 // « ^ / f^^jji iiL_£|Ass^' iOX MAT£_FCc 30 '/ i rr^T^T^^^ ^ — .f 150 / L.^/j U<^ "■/ A <^ CD V/: ^y 120 \ i V _,.2^L.^:^ M 20 \ \\t 1.^ /^ 1 V f ^/ A" IWW- -QIV Xb'X i/^i ^ /r /^°v: 1 1 nw^ r- i^u lS.^'> Hn 5(i- -» 10 / A* l/i l/l |>^ / XC 1 ^ III .^^^BIS f F ! 1 < 1 1 ) » 3D 40 SO , 60 i TO 1 ep 1 90 { 100 1 Amperes j | | 1 M ' 1 Fi? . 4. Characteristic Curves of Railway Motor. motor, therefore, furni.shes this great .starting torcjue more economically than a .shunt-wound motor the tonpie of which is projM)rtioncer study of the curves. ELECTRIC RAILWAYS 5 The fields are worked near the ])oint of niaji;netic saturation. This economizes metal and space and is also an advantage because of. the fact that when so worked the armature reactions have verv little eli'ect on the fields. 'I'he neutral j)()int.>+ between fields are consequently shifted very little and it is therefore not necessarv to shift the brushes when the motor is reversed. Armature Winding. 'J'he armature v^.! :f ■* «(-x OC l^ 00 T-H CCi l-- 00 CO CI CC CO (TO iM CO c 1^ IH ■? a '^ rtf M|-.C C^y5 r-|*l r-YM ''■'1' >0 O O (- O CO ^ '-['"I t-''/: r-l"* ifr'y; ^;?i ^'^3 CO Ol Ol CO Ol CI CO •S^IS^'0 put! sjtiao cr 'O O O lO lO »-0 CO w ^ C: 'X 'X T-^ CO (M CO -*i CO ca -^ •a^aiclraoo ojinijui.iv CO t^ '^ O >0 lO lO >o >o o '-0 c; c-j ^ O CO t^ lO O CO 00 I— ( lO lO — I 1— * •lots jad s.iojonpiio.) C-1 -^ 00 CO CO T— I CI >— 1 r-^ •siois i^ o CO t^ r^ CO CI CO -f CO saanxmaktlfmox »6 o CO ^^ ^^ lO ^^ >— I •ptjoi n^Ll paads o o o Tt< Tfl t^ CO CO ■* saaacltuv to o CO ■JaAVOd asJOH C^ t^ 0 to GO CI »0 O 'tT CI CO u o o o p. 1— I C^ t^ to t^ •<* "^ »0 tO tO lO CO >o t^ -t-J u c o X CO . ^ ■^ CO CO "^ I— 1 T— < T-H 1-^ CO 1— 1 l^ 1^ Oi X "--1 t^ rt^ r-)CI Htl CO CI CO CO CI O ^O X t^ CO CI CI CO CO CI o o o o CO CO CO CI CO CO X l^ .327 'O 'O lO »o Q X o X o o CO >o CO iO CO 'f o o o o o lO X >o '^ o 1^ CJ CI o X c >o C-. CI i-H CO CO lO 1— t o >o 1^ t^ lO r^ O O ' — I ' — ' 1 — I >— I CI CO lO »0 Oi O lO cj >0 CO CO CO lO 'O O O to 'O O to Tfi CO l^ >0 lO CO X Ci O O O Ci CO CO i^ »o to -^ CD w 3 o r-i fee B *^ -<^ (Zl ELECTRIC RAILWAYS By reference to tlie windiiif]; diagram given in Fig. 5, it may be noted that a complete circuit through two coils ends at the seg- ment adjacent to the one from which the start was made. It may also be noted in the table of motor data that all of the armatures have an odd nimiber of segments and an odd number of slots. It is absolutelv necessarv in a wave windin«jj to have an odd number- of segments. Otherwise the winding could not be made symmetrical and the circuit through two coils be made to return to a segment adjacent to that from which the start was made. ^Yith equal spacing between the top and bottom leads of the two coils, an even number of segments would make the circuit return either on the segment from which the start was made or two segments from it. The first drum-wound street railwav motor armatures had as many slots in the armature as there were coils and segments. The great number of slots necessarily made the teeth very thin and con- secpiently weak. This is very objectionable as sometimes the arma- ture bearings wear away, allowing the face of the armature to drag on the pole pieces and thin teeth are bent out of shape. Armatures are now almost entirely constructed with either two or three coils to a slot. When two coils are used in each slot with an odd number of slots an even number of coils results. If these were all connected to the commutator an even number of segments would be necessary. As this is not possible with a wave winding, one of the coils is "cut out." The ends are cut short and taped and it is termed a "dead" coil. This makes the winding somewhat unsym- metrical, all the coils not bearing the same angular relation to the commutator segments to which they are connected. This difference is, however, not great enough to affect the operation of the machine. The Westinghouse 49 motor is an example of an armature with a dead coil. By reference to the table of motor data it will be seen that this armature has 59 slots. Two coils in each slot would make 118 coils. One of these, however, is cut out, giving 117 segments. Cutting out a coil can be avoided by putting three coils in each slot. An odd number of coils results then no matter what the number of slots may be. In the majority of examples given in the table there are three times as many segments as slots. 8 • ELECTRIC RAILWAYS The sides of the slots of modern street railway armatures are strai<;ht. Tlie coils are prevented from Hyinfj out l)y l)ands of wire extendiufj; over the tops of the coils around the armature. Steel or silicon bronze wire of about No. 14 gauge is used. Recesses are made in the armature teeth for the reception of these bands so that the wire when womid will come flush with the face of the armatiu'e. The bands are usually 4 to 1 \ inches wide. The wires are well soldered together to secure them in ])lace. One trouble experienced with armatures is the slipping off of these bands. The heated armature expands and stretches them. ^Vhen the armature cools ^^^^ Fig. C). ArnKitnvf ( 'oil. the bands are loose and then often slip off. "When they do so the coils lly out by centrifugal force, strike the pole pieces and groimd the motor. Armature Coils. Railway motor armatures are to-day imi- versally constructed with form-wound coils, wiiich are wound on a form of proper shape and carefully insulated before l)eing placed in the armature. The coils of the smaller motors (those \\\) to 40 or .')() h()rsej)ower) are usuallv wound with round wire. 'I'he cotton covering of the wire is de])ended u])on for insulation To strengthen this, however, t!ie coils after being wound are immersed in an insulating compoimd and then baked in an oven. The whole coil is usually wrapped with insulating tape (See Fig. (>). The armatures of larger motors have coils made of copper bars. Mica is often placed between and around the bars for insulation, though oiled linen cloth tape cut bias is also employed, especially in repair work. Field Coils. Field coils are so constructed that they may be readily removed should they become grounded or .short-circuited. ELECTRIC KAILWAWS Some niiikers wind tlieiii on a l)rass shell or form which is slipped over the ])ole j)ie(e. In some motors the field eoils are composed of copper rih!)on, wound hare, with rihhons of insulatini- riotor Suspension, 'J'wo methods (;f suspending motors flex- ibly on trucks are in common use. That end of the motor which has bearings on the car axle cannot, of cour.se, be, flexibly suspended with regard to the axle; but the other end of the motor can be placed on springs, or re.st on a bar suj)ported on sj)rings, as .shown in Fig. 14. This suspension is commonly called no.sc .su.spen.s'tofi. Instead of having a special bar and special s])rings for the nose of the motor, the nose ni ay rest upon some part of the truck that is carried upon springs. Thus, on the IVI. C. B. type of swivel truck, the nose usually rests on the truck bolster, and thus gets the benefit both of the bolster .springs and of the ecpiali'/er .springs of the truck. Another general ])lan of suspension is that known in one form as cradle -fus- 'pensicm, and in another form as sidc-lxir suspension. A si(le-l)ar suspension is shown in Fig. 1"). Here a larger percentage of the weight of the motor is evidently taken by the s])rings than in the case of nose suspension. It is desiral)li> to relieve the car axle of as ELECTRIC RAILWAYS 15 much dead weight as possible. By dead weight is meant weight resting upon it without the intervention of springs. Motors of the New York Central Electric Locomotive. These motors are a radical departure from the usual type of rail- ''^ , ' "T "J tf. / ' * 3 1 0) « i o ( \ Z 1 1 i *^ \ Fig. ''^\'- L^-t- way motors. The locomotive on which they are mounted has four driving axles, upon each of which is mounted an armature, direct, no gears being used. Figs. 16 and 17. The motors are remarkable for three .special features: The method of mounting the armature, the shape of the pole pieces, and the path of the magnetic flux. 16 ELEC'TUIC KAILWAYS The nioiintinfj of the arnmtiire upon the driving axle and tlie motor fields on the tnu-k frame makes it necessary to liave Hat pole pieces in order that the armature may play uj) and down as the journal l)ox and axle slide in the guides of the truck frame. The shape of the pole pieces may be ol)- served in the drawing Fig. IG. When in the central position there is a 3 -inch air gap between ~ the armature and pole § pieces. The magnetic \ flux is continuous through £ the fields of all four of f the motors. It returns t through the cast steel ■;" side frames of the truck 5? and two bars placed in i the path. f The brush holders ^ are so mounted that the .5 brushes ()ccu])y a fixed z position relative to tlie I armature. The arma- ture is removed by low- ~. ering it with the wheels '^ and axle upon which it is mounted. This can be done without disturbing the fields of the motor. CONTROLLERS. In an ordinary electric car, current is taken from tlie wire through the trolley wheel and ])ole, and is first led from the trollev base throui;h overhead switches or a circuit breaker, and then to the controller, from which it passes through the motors and Q <: o a: .J < < EC H Z M U cc ° i ^ a z o cc '^^ o t; u, ^ a w ^ > rt O ^ s y^ o " o o cc H u u z o , H in 01 -HI i^ ABvaan ELECTRIC RAILWAYS 17 thence througli the motor frames, car truck, and wheels to the rails and ground. If the car is designed to be operated from either end, an overhead switch or circuit breaker is placed over each phitform of the car so that current can instantly be cut off entirely from the controllers by throwing the switch or circuit breaker at either end of the car. Fig. 17. Armat nn; Axle ami Wheels. The lighting circuit is run from the trolley base independently of the motor circuit, and has its own switch and fuse box. Current for the lights is taken from the trolley circuit before it reaches the main switches or circuit l)reakers. furrent for electric heaters, if such are used, is likewise taken from a separate circuit. On a oOO- volt system five 100-volt lamps are usually connected in series for car lighting. As many multiples of five can be employed as are necessary to light the car. Rheostat Control. The simplest form of controller is that employed where only one motor is u.sed on a car. A rheostat is placed in series with the motor when started, just as on a stationary motor; and the function of the controller is to short-circuit this resistance gradually until it is entirely cut out and the motor operates with the full voltage. The controller also has a leversing switch by means of which the relative connections of the armature and fields are reversed, which, of course, changes the direction of rotation of the motor armature. Such a simple e(juipment as this, however, is rarely to be found in practice. Series=Parallel Control. Single-truck cars usually have two motors, one on each axle; and on such cars a series-parallel controller 18 ELECTRIC KAIL WAYS is tlu' kind usuallv cuiplinrd. l)iati,rams of coiiiu'ctidiis on the various points of a series-parallel controller (Type K (1) of the (ien- eral Electric Company, are given in Fig. IS. ^Ofnf Res/stance Mo/or f Motor 2 Armafure rie/cf Armature Fie/cf -=-wwvwy p-ijr. 18. Diagram of K6( out rolk'iCombinatious. From these (lia}i!;rams it is seen that the motors are first o|)era.teCVM5 ^Oc/'QM" - ELECTRIC RAILWAYS "*• CfKOUNO Fig. 23. Motors in Series. All Imt the lower \\\v .sctriiic'iit.s of the cvliiider tire electrltallv con- netted togetlu-i' hy mean.s of the iron cylinder upon which they are ir.ounted. On the first point then the current pas.ses from the cylinder over H,, and with ,strai<;ht series connections of the resi.st- ances, it goes through all of the rheostats under the car, and returns to the controller over the last resistance lead, Ilj. Behind the motor cut-out switches at the base of the controller this lead istap- ])cil into a wire one end of which leads to finger 1*.) of the controller, and the other end through the cut-out switch and reverse cylinder to No. 1 armature. The current takes the latter path, pas.ses through the armature of the motor and returns hv wav of the reverse cylinder, thence throuHi the fields of Xo. ] motor and then through the cut-out switch of No. 1 motor and to finger E , , of the controller. Seg- ments (), M, Nand !>, shown in Fig. 2.3, and corre.spond- ing segments of Figs. 22 and 24, are insulated from the remainder of the con- troller cylinder. From finger E, and segment () f Fig. 23) the current pas.ses over finger 1.'3 through No. 2 cut-out switch and the reverse cylinder to the arm- ature of No. 2 luotor. Returning ii passes through the reverse cylinder, then hack through the fields of No. 2 motor and to the Fin. -JJ C/'OUNO. Motors ill Purallel. ELECTRIC RAILWAYS 23 ground, which is usually through a connection on the motor casing. C)n points 2, 3, 4 and 5, the successive series points of the con- troller I{|, K , etc., make contact with segn.ents B, C, etc., Figs. 23 and 24, until finally finger 10 rests on segments J, the resistance is ail cut out and the motors are connccte IS B Vis. Ofi. 'Reverse Position of Reverse. ELECTRIC KAILWAYS. 25 26 ELECTKIC KAIL WAYS first ]K)int the current returns over R, to the controller cylinder. It passes off through a collar at the base of tlie cylinder through No. 1 cut-out, and the reverse, which is shown in the central position, to No. 1 motor. On returning lo the controller over K, it passes to t!;e upper section of the coniniutating arm. In the diagram this is shown in the central position. In series it is thrown to the left. The current then passes from the commutating arm to No. 2 cut-out, and to No. 2 motor. jMovement of the controller handle further nniltiplies the paths through the rheostats and finally, when fingers S rest on the cylinder, the rheostats are short-circuited. If the con- troller handle is moved still farther, the rheostat cylinder is returned to the off position and the commutating arm is thrown to the left. ^Yith the arm in this position the current divides, one portion passing to No. 1 motor as before and to ground by way of the upper section of the commutating arm ; while the other branch goes by way of the lower section of the commutating arm to the cut-out switch for No. 2 motor and thence to the motor. Reversing is accomplished by onc-({uartcr revolutions to the riffht and left of the segments shown. It is evident that this will ccmnect either A, or A A,, to the trolley. And likt-wise connect the other armature leads. Reversal. The reversing handle and the main controller handle are made interlocking so that the motors cannot be reversed without first throwing the controller to off position. This is to pre- vent daiuage to the motors through careless or inadvertent throwing of the reverse handle when the controller is on some of its higher points. Such a reversal would cause an enormous current to flow through the motors, and would l)e likely to damage them and to open all the circuit breakers and fuses in that circuit. The reason for the enormous flow of current is, of course, that the coimter- electromotive force of the motors, when reversed with the car going at some speed, would materially add to the electromotive force of the trollev line, instead of opposing it as when the cars are in opera- tion. The current flowing through the motor circuit would then be e([\\a\ to {clecfromotivc force of line + clcciromotivc force of moiors) -r- {resisiance of .noiors), which would result in a very large current. riagnetic Blow=Out. On the Type K controller as well as on most other successful controllers, the flashing or arcing l>et\veen ELECTRIC RAILWAYS . 27 contact rings and fingers, which occurs when the circuit is broken, is materially reduced by a magnet that produces what is called the magnetic blow-out to extinguish the arc. This magnet derives its current from the main circuit, and is so arranged as to create a stnmg magnetic field in the neighborhood of the place where the arc is formed Fig. 21 shows a Type K controller open with the magnetic blow-out magnet thrown back on a hinge. The coil which produces this magnet is seen in the right side of the con- troller. The main contact drum is in the middle, and the revers- intr drum at the right hand. There are in use a number of other controllers built upon these same general principles but differing in mechanical arrangement. Controller Notches. All controllers are provided with some device which prevents the motorman from stopping the controller handle between the various points or notches, as the stopping be- tween points might result in drawing an arc or an imperfect con- tact. The most common arrangement to prevent this is a notched wheel on the controller shaft, against which bears a small wheel of just the right size to enter the notches. The small wheel is held against the notched wheel by a strong spring. As the tendency of the small wheel is to seek the bottom of the notches, it is diffi- cult to stop the controller handle anywhere between notches, and the motorman is thus given a guide which tells him without any effort on his part just where the notches are. To prevent advancing the controller handle too rapidly and avoid the jerking of passengers, excessive currents and slipping of wheels during acceleration, several devices have l)een planned. On the multiple unit control systems, a limit switch is usually provided which prevents the controller advancing when the current exceeds a predetermined amount. A device to accomplish the same results on the K type of controllers is teriiied the Automotoneer. A cam connected with a dash pot prevents movement of the controller handle to the successive notches faster than a previously prescribed rate. A switcii is usually pnn'ided in a controller, for cutting out of service one motor or a pair of motors if defective, and allowing the car to proceed with the good motor or motors. 28 ELECTRIC llAILWAYS. V ^^ ral [rx jm m\ ' ■nJ5»J11i!_Mt 4^ M. (A if. U) fcC ^ VI en o H < C6 M Z M U O o ^ / 1 U Si u ~ a: ^ o u — " 0. ri >- ^ H ■^ rS U ^^ z ■/; (■5 :2 Z ._> H yi Z •a OS c3 o; o u bl) u cS o H ;a (J ■J M , K •J ^^ rt Q ;] a o ^ d «■ o io o '2 o CO 4^ «A C4 3 O X o z H (/] b] & LIBRARV OF THE ^IVERSITV oflUINQl ELECTRIC RAILWAYS 29 MULTIPLE=UN1T CONTROL. A system called 'Snultij)le-iinit control" or "train control" has come into nse where it is desired to operate motors imder a number of different cars in a train; all the motors being controlled from the head of the train or from any other point on the train where the inotorman may be stationed. There are several types of multiple-unit control, in all of tlieni there is on each car a controller of some kind which controls the current flowing to the motors on that car. This controller is operated from a distance by means of electro-magnetic or electro-pneiunatic devices controlled by circuits called jjilot circuits, which circuits are connected to the motorman's controller. x\ll the pilot circuits of a train are connected together by means of train plugs which make the connections between the cars. The pilot circuits of each car are connected to a motorman's controller on that car and this makes it possil)le to operate the train from any controller. Sprague Multiple=LJnit System. Jn the earliest form of multiple-unit control — which was that devised by F. J. Sprague — the motors on each car were controlled by an ordinary Type K con- troller, which had geared to its shaft a small ])ilot motor. The pilot motor was controlled by the pilot circuits connected with the motorman's controller. In the more recent forms of multiple-imit control, the use of main controllers having contact cylinders has been practically aban- doned. Tlie contacts are made instead by a number of electro-mag- netic or electro-pneumatic contact devices sometimes called coniaciors. General Electric Train Control. In the General Electric train-control system each contact for the motor circuits is made by a solenoid magnet which draws together two heavy copper con- tact fingers to establish the circuit. A magnetic blow-out coil in series with the contact is also provided. The contactors make contact only when energized by a small amoun.t of cm-rent from the master or motorman's controller. In Fig. 2S« is a diagram of the car wiring for a motor car equipped with this system. The motorman's controller is a drum controller, but is comparatively small since it has to handle only the small amount of curreirt necessary to opc'-ate the solenoid magnets of the contactors. It is evident 30 ELECTKIC KAILWAYS that l)_v coiiiuTtiiii;' tc)*;vther the pilot ciix'iit.s, %vhich are eoniiected to the niotornian's controller, so that the pilot circuits will be continu- ous for the entire length of the train, any number of cars ecjuipped with the train-control system can be ojjcrated; aiwi similar contacts will be made by tiic contactors under all the cars simultaneously, by virtue of the circuits established by the master controller at any platform. Besides controlling tlic contactors, the master or niotornian's controller must control an electro-magnetic reversing switch, or reverscr, to change the direction of car travel. The handle of the niotornian's controller is provided with a push button, which must be depressed while the current is turned on. Should the motorman release this push, the circuit through the controller will be opened and all the contactors will fall open. This handle is called the dead nian's handle because it is put the'^e to j)rovi(le for cutting off the current should the motorman fall dead or in a faint at his post. The flow of the ciu'rent in the control circuits, which operates the reverser and picks up the contactors on the several points may be followed in the diagram Fig. 28rt. With the reverse handle in the forward })osition and the controller on the first point, current ])asses fnmi the main circuit through a single-pole fused switch called the control switch and through the auxiliarv blow-out coil to a finger bearing on the upper section of the master controller cylinder by which connection is established to the atljacent finger and thence to the reverse cvlinder. It leaves this over wire Xo. S, passing by way of the connection board and control cut-out switch to the forward operating coil of the reverser, thence through the forward blow-out coil and over wire 81, through the switch under- neath contactor No. 2 and to ground G, by way of wire B 2 after passing through the fuse shown. The current through the operating coil of the reverser, having thrown tliis, the })ath is changed some- what. The current then instead of passing from the rever.ser over wire 81, is conducted through wire 15, through the operating coils of contactors No. 1, 2, 8, and 11 in series, through the switch under contactor No. 12, and to ground through finger 1 of the controller. Contactors 1 and 2 are in multiple and when raised connect the trollev with the contactors controllinji; the resistance leads. Con- ELECTRIC RAILWAYS 31 tactor 3 connects 11 to the line while contactor 11 places the two motors in series. The motors then operate with all of the resistance in circuit. When contactor 2 raises, it opens the switch immediately below it, making it impossible for the reverse to operate while current is flowing through the motors. On the second notch of the controller an additional })atli is opened by way of finger 3 of the controller. This path leads from finger 3 through four of the control circuit rheostat coils, through contactor No. 5 and to ground over 32. ( )n the 3rd, 4th and 5th points contactors G, 7 and 9 respectively are raised. The motors are then in full series. Between the 5th and 6th points all the control circuits are broken preparatory to starting the multiple connections of motors. On the 6th or the first multiple point the ground through finger 1 of the master controller is'opened while a ground through finger 3 is established. The current from the reverser then, after raising contactors 1 and 2 as before, instead of passing through contactors 3 and 11, passes through the coils of 4, 12 and 13, through the switch under contactor 11 and to ground over finger 2. Contactor 12 connects motor No. 2 to Rj, while contactor 13 grounds No. 1 motor. The motors now operate in parallel and on successive notches of the controller, contactors 6, 7, 8, and 9 are raised, cutting out all of the resistance. The switches underneath contactors 11 and 12 make it nn possible for 11 to raise with 12 and 13 or vice versa. The reason for this arrangement is very evident, as a direct ground for R^ would result. The Westinghouse Electro=Pneumatic System of ControL In this system of multiple unit or train control, the current to the motors is supplied through a set of unit switches or circuit breakers which are sometimes placed in a circular case or turret underneath the car and in other cases are ranged in a row under the car. The opening and closing of these unit switches is done with compressed air actmg on a piston in an air cylinder. When the circuit is to be closed, compressed air is admitted behind the piston and forces it down against the tension of a seventy-poimd spring, and the contacts are brought together. When the switch is to be opened, the air is let out of the cylinder and the spring forces the piston back. The air supply is obtained from the storage tanks of the air brake system. The valve controlling the air supply to the cylinder of each unit "twitch is operated by electromagnets which derive current from a 32 ELECTRIC RAILWAYS seven cell, fourteeii-volt, storai^e battery. The small master coii- j^o ;/>j ■-♦«• ^ui 7 y f/V x^ uoijou^f OOOOOOOOO '->(^y^^ 1(0°^ f 9 '■''-■/ gLZ /./oj i.Ass^ffo troller operated by the motorman, makes and breaks the battery connections to the majjnets controlling the air valves. An advantage of this over other mnltiple-unit systems is that by ELECTRIC RAILWAYS 33 the use of battery ciinent the control system is not (Hsturl)ecl by interruptions of the main supply of current. The chief advantage of this is that it makes it possible to reverse the motors and operate them as brakes in emergencies at all times. The battery is charged from the nuiin line through lamps as resistance, or may be charged by being connected in series with the air compressor motor. In the accompanying diagram, Fig. 2.S /;, there are two batteries shown which are charged in series with the compressor motor. Bv means of two double-pole, double-throw switches, first one and then the other battery is connected for charging and for service. The battery is charged, in shunt with a resistance and a relay is connected in the circuit as shown, so as to open the battery circuit whenever the current through the motor stops, and thus prevent the battery discharging through the resistance. The master controller has a double set of segments in order to decrease the length of the shaft. The handle, therefore, is moved only one-sixth of a revolution from oft" to full speed. The various circuits can be traced by the letters and mnnbers each wire bears, so that the circuits will not be gone over in detail. The first position of the master controller throws the reverser switch in the proper direction and also closes the main circuit breaker. On the second point the motors are connected in series with all resistance in circuit, and these resistances are automatically cut out one by one. On the next point of the controller the motors are in multiple and the resist- ances are automatically cut out in a similar manner. The automatic cutting out of resistances is accomplished by a limit switch in con- junction with operating and holding coils on the electro-pneumatic valves. This limit switch is a kind of a relay which has the current from one of the motors flowing through its coil and which acts to open a certain battery circuit which operates the electro-pneumatic valves whenever the current in the motor circuit in question exceeds the amount for which the limit switch is set. The automatic accelera- tion or cutting out of resistance is accomplished as follows: Each electro-pneiunatic valve has two magnet coils, one of which is an operating coil and the other a holding coil for holding the valve open after it is operated. When first the cm-rent flows through a circuit to one o^ the electro-pneumatic valves, it flows through the 34 ELECTKIC RAILWAYS operatiiit; coil and operates the val\»' to close the corrc .;j)on(li)i<:; switch or switches of the main circuit by turninif the air into the cylin- ders. As soon as the main switch is closed, it cuts into circuit the holding cril of its corres])ondino; electr()-j)neuniatic valve and this coil will, with the hattery current, hold the switch closed even thouj^h the circuit to the ()])eratin[. Fig. 34 shows the hand-operated circuit breakers connected in series. 'J'his method is used where non-automatic breakers are employed, but for automatic breakers it has the objection that an overload would throw the breaker set at the lowest point. This might be the breaker on the opposite end to that occupied by the motorman and in such an event would necessitate a trip to the other end to set the breaker. ELECTKIC KAILWAYS 41 Fig. 36 shows a iiietluxl of parallel connection re(juiring but one lightning arrester. This method has the objection that the niotornian on the front end would have no assurance that by throwing the breaker over him the power would be cut off. The rear breaker might have l)ccn carelessly left set. V" ^ I ^ ] Fig. 85. Fuses. A fuse is placed in series with the motor circuit before it enters the controller wiring, but where circuit breakers are used instead of canopy switches, the fuse box may sometimes be dispensed with. The fuse box on street cars is usually located underneath one side of the car body where it is accessible for replacing fuses, but where a motorman's cab is used, the fuse may be placed in the cab. The fuse may be of any of the types in c(mimon use, either open or enclosed. In the Westinghouse fuse box it is necessary only to open tlie box and drop in a piece of straight copper wure of the right length and size. The closing of the box clamps this wire to the termi- nals and establishes a circuit through the cop- per wire as a fuse. Of course this copper wire is of small enough size to be fused by a danger- ously heavy current. Lightning Arresters. A lightning arrester is used on all cars taking current from overhead lines. The lightning arrester is connected to the Fig. ;;g. main circuit as it conies from the trolley base, before it reaches any of the other electrical de- vices on the car, so that it may afford them ])rotection. A conunon type of lightning arrester is shown in Fig. 3(). One lernunal of the 12 ELECTRIC RAILWAYS lij;litiiiiig arrester is connected to the motor frame so as to .ground it, and the other is connected with the trolley. In most forms of lightning arrester, a small air gap is provided, not such as to |x?r- mit the 500-volt current to jump across, but across which the light- ning will jinnj) on account of its high potential. To prevent an arc being established across the air gap by the power house cun-ejit after the lightning discharge has taken place and started the arc, some means of extinguishing the arc is provided. In the General Electric Company's lightning arrester, the arc is extinguished by a magnetic blow-out, which is energized by the current that flows Trolley \Fuse \2 Point Switch Sign Light. o- Platrorrm Light o o o o o- ■o Sign Light Plat forn^ Light. ^9 I 7 4 Point Double 1 '/ hro^t/ S^/^itch C^Heaa Light Head Light \ Fifj ST. Di:i9. A'arious com])anies use various Fig. Kt. Trolley Wheel. ELECTRIC RAILWAYS 45 forms of groove in the trolley wheels, some adopting a groove approxi- mately V-shape ce 3 CQ O a tc to 1> < s o H < ELECTKIC KAILWAYS 53 a wav to permit a staiulard M. ( '. B. Ilaiiue to j)ass through. Some street raihvays use flanges as sliallow as ^-incli, althougli ]-inch is most common on citv work. The width of tlie tread on street railway cars, that is, tlie width of the wheel where it bears on the rail, is usually from If inches to 2j inches. There is a tendency, however, on electric railways, on account of the increasing number of interurban cars which nnist use city tracks, to Iniild tracks that will accommodate wheels approaching the INI. C. B. standard of steam roads. A few roads have adopted wheel treads and flanges very near to the :\I. C. B. standard. Brake Rigging. The brake rigging on a single-truck car may be arranged in a variety of ways, but should be sucli that a nearly equal pressure will ]>c brouoht tol)ear on the brake shoes on all four wheels. A typical arrangement of brake shoes and levers for single-truck cars is shown in Fig. 40. The rods R terminate in chains winding around the brake staff upon which the motorman's handle or hand wheel is mounted. For double-truck cars the brake rigging is necessarily more complicated, as it must be arranged to give an equal pressure on all eight wheels of the car. Brake shoes are sometimes placed between the wheels of a truck and sometimes outside. The arrange- ment of brake shoes between wheels is appar- ently finding most favor, ,as when the shoes are applied in this position there is less tend- ency to tilt the truck framt> when the brakes are applied, and this adds to the comfort of passengers in riding. Fig. !^0 shows one form of arrangement of brake levers common on a ELECTRIC liAlLWAYS doulde-tiufk car ('(jiiijiped witli air Urakes. witli iiisi(le-luino| Itrake slioes. Brake Leverages and Shoe Pressure. The levers between the air cylinder and the ])rake shoes are usually so proportioned that with an air jiressureol" 70 11)S. per S(p in. in the brake cylinders the total of the brake shoe pressures on the wheels will be equal to about '.to ])ercentof the weight of the car. The dian-rani F'm. 51 has shoe j)ressures and strains in the several rods marked on shoes and rods. The following example, based on the diagram, will explain the lever proportioning. Only round numbers are given on the diacrram. Assume a four-motor car weighing 40.000 pounds. A brake cylinder 7 inches in diameter is used. This gives H8.5 square inches and at 70 pounds air pressure a total force on the piston rod of 2,695 pounds. The weight of the car is 40,000 pounds. Taking 00 per cent of this gives a total of 36,000 pounds to be exerted by the brake shoe when an emergency stop is made. Each of the eight shoes will press against the wheels with a force of 4,500 ])()unds. The dimensions of th(^ ti'uck are such that the "dead levers," those lixed at one end and which carry shoes, cannot be over 18 inches long. The shoe will be hung three inches from one end. making the proportions 10 to 8, and the pressure on the strut rod between shoes will be 4,500 X \l or 3, 461 pounds. To clear the truck frame the live lever extends 14 inches above the point of application of the brake shoe. To obtain 4,5()0 pounds pressure on the shoe, the distance between the brake shoe and the strut rod, which we will call "a*," will be found by regardinca- the U])T)er end of the lever as iixed and the power applied at the lower end. 14 + rr 4500 = 3461 X ^ or X = 4,2 inches. Now to obtain the force required in the rod to the truck quad- rant, the bottom end of the live lever must l)e reofarded as the fulcrum. The equation is X = 4500 X |7TT) = 10.38 pounds. ELECTRIC RAILWAYS 55 As the pull rods from each side of the truck are attached to the truck ([uadrant, the stresses iu the ])rake rods are double this, or 2,076 pounds. The position of the brake cyl- inder under the car restricts the length of the "live" and "dead" cylinder levers to Hi inches. To obtain 2,076 pounds pull on one end of the levers with the previously computed 2,695 pounds on the other, the proportions 2076 X . must be f-^^ ' = TTT? since 2076 + 2695 --- 4771. Then x = 7 inches, the distance from the brake piston to the pivotal point. Since 2,695 pounds pressure is exerted and 36,000 poiuids results the proportion of the whole system of levers is 36,000 to 2,695 oi- 13.3 to 1. In other words the travel of the piston in the cylinder will be 13.3 times that of the shoes if there were no lost motion to be taken up. The piston travel should be from 4 to 5^j inches. This gives about |-inch travel of the brake shoes. Increased travel of the brake shoes necessary to set them as they wear away causes increased travel of the piston of the air cylinder. Not only is more air used at each application of the l)rakes l)ut the brakes are slower in acting. It is therefore 56 ELECTKIC RAILWAYS necessary to luljust the brakes frecjuently. This is done in the sys- tem shown in the diagram hy the use of a turnl)iic'kle in the con- necting rod between tlie hve and dead levers of the truck. When two motors arc on one truck and none on tlie other, allowance must l)c made in the levers for the increased weight of the motor truck and the inertia of the armature. The leverage on the motor truck nuist be greater than on the other. Air Brakes. Air brakes used on electric railway cars are usually of what is called the straight air brake type in distinction to the Wesiinghouse automatic air J>rake. A straight air brake is one in which the air is stored in a reservoir; and, when the brakes are to be applied, air from this reservoir is turned directly into the brake cylinder, in which works a piston operating the brake lever^-. Air admitted behind the piston forces it out with a pressure which applies the brakes. When the air is let out of the brake cylinder, a spiral spring forces the piston back to its original position and the brakes are released. The motorman's valve by which he applies the brakes, therefore, provides, first, for turning air from the storage reservoir to the brake cylinder to apply the brakes, and, second, for closing the opening to the storage reservoir and opening an exhaust passage from the brake cylinder so that the air can escape from the brake cylinder to release the brakes. Straight air brakes of this kind would not be suited to the opera- tion of long trains, because, if the air-brake hose connection l)etween cars should be broken, the brakes would be useless; but for trains of one or two cars, such as are common in electric railway practice, the simplicity of the straight air brake outweighs its disadvantages and this is the type of brake usually employed. (See Fig. 52.) The Westinghouse and other forms of automatic air l)rake are used on electric railways where cars are operated in long trains; but it is out of the province of this })aper to describe these brake systems fully, as they arc rather complicatcMl. Tt may be said in general, however, that the Westinghouse automatic air brake is so arranged that, should the hose connection between cars be broken, shoidd the train ])nll in two, or should anything happen to reduce the pressure which is maintained in the train ]Mpe that runs the length of the train, the brakes would immediately be applied on the entire train. ELECTRIC RAILWAYS 57 &^, puno-i^ ql K Compressors. A small air coinpresscr driven by an electric motor is frequently employed on electric cars to keep the storage reserv'oir of the car sup])lied with air. These air compressors are carried under the car or in the motorman's cai). They are generally arranged with an auto- matic device which closes the motor circuit and starts the motor as soon as the air pressure falls below a certain amount; and the motor will continue in operation pumping air until the pressure rises to the amount for which the auto- ? matic device is set. The pressure carried .£- in the storage reservoir is usually from $ GO t;) 90 pounds per square inch, \vhich, :^ as a general thing, is considerably more than is required to apply the brakes hard enough to slide the wheels. Automatic Governor for Air Com= pressors. Automatic governors are often installed in connection with air compress- oi-s in order that a fairly even air pressure may be maintained in the storage reservoir. In these the fall and rise of the air pres- sure within certain limits closes and opens the circuits to the motor. In some styles the air acting on a piston operates the circuit breaker. The diagram shown in Fig. 53 shows the principleof the Christensen governor., in which the air pressure is employed lo make and break a secondary circuit. ^Vhen the pressure in the storage res- ervoir falls below a predetermined value, the hand of the air gauge makes con- tact with lug A. This closes tl:c circuit through solenoid Xo. 1. Lug l),nicchau- U 58 ELECTKIC KAILWAYS ically connected to the armature of the solenoids is pulled in con- tact with lug (\ and this closes the circuit to the motor, and shunts the winding; of solenoid No. 1. Wlicn the air pressure rises to a predetermined value the hand of the air gauge is thrown in contact with lug B. This energizes solenoid 2 ])y connecting it across the motor terminals. The armature is pulled to the right and the circuit to the motor is broken. ^Vhen this is done it is evident that the current through the energized solenoid is broken. It is evident from the descrij)tion that current j)asses through the .solenoids Trolley i K Solenoid I D ^ c Compresso, Motor Fields Ground Fig. oH. K K Solenoid H onlv during the .sfiort j)erioLL---- -_-. ^ -_4 4 ^ -^ J-. i!- Sij| ^- Charging Coupling Fig. .55. Arrangement of Storage Air Brake Apparatus. Ill the Price momentum brake a Hat tlisc is cast on the car wheel, which is turned off to a smooth surface. Against this disc a friction clutch acts, which has a leather face. The clutch is operated bv a motorman's lever through a .set of levers. A small movement in the motorman's lever forces the clutch against the disc on the car axle. The clutch winds up the brake chain, and thus supj)lies power to apply the brakes. Other momentum or friction clutch iirakes have been devi.sed, most of which also use an application of Jeather on iron for the clutch, as this has been found to be most reliable, and to be least affected bv the irrease and dirt that is liable to work in l>etween the clutch SI u-fac •es. ELECTRIC RAILWAYS 61 Q. E. Electric Brake. The (Teneral Elective i^ompany's elec- tric brake makes use of current generated by the motors actmg as dynamos, to stop the car. In N)rder to accomplish this, a brake controller is provided which reverses the armature connections of the motors, and so ?onnects them to operate as dynamos sending current +Jirough a resistance in the circuit; the amount of current flowing and the braking eflect depending on the car speed and the resistance In some forms of brake controller, the two controllers are ccmibined in one cylinder, so that the motorman, to apply the electric brake, simply continues the movement of the handle past the "off" position. In others, the brake-controller drum is sep- arate, but is interlocked with the main controller so that it can be used only when the main controller is off. However the controller may be arranged, the principle in- volved is that when the motors are revolving by the motion of the car, and the armature connections are reversed as they woidd be to reverse the direction of motion of the car, the motors begin to generate current as series-wound dynamos. The amount of current generated and the retarding effect will depend on two things — namely, the speed of the car, with the consequent electromotive force in the motors, and the amount of resistance in the circuit. The amount of resistance is regulated by the motorman by means of his electric brake controller. The function of the electric brake controller is to reverse the motors and to insert enough resistance in the circuit to make a comfortable stop. This current in the motors acting as dynamos, in itself acts as a powerful brake to retard the motion of the car. In the General Electric type of electric brake, the current generated in the motors, in addition to having this retarding effect in the motors themselves, is conducted to brake discs that act as magnetic clutches against one of the car wheels on each axle. The car wheel has a disc cast upon it, and against this the magnetic disc acts. The magnetic disc contains a coil which is in series in the brake circuit. In applying an electric brake of this kind Uic motorman first puts the controller on a point that inserts considerable resistance in the circuit. When the motors have slowed down, the electromo- tive force, of course, drops, so that to maintain the same braking current thcie iinist be a reduction of the amount of resistance, until, G2 ELECTRIC RAILWAYS wlion the car is uliuost at a .standstill, the resistanee is nearly all cut out. It niiijht .seem at first that the current would die down hefore the car came to a .stop, but it is found that there is enough induction in the motor fields to cau.se current to flow for a .short time after the car has stopped. The residual magnetism in the .steel in the fields of the motor is sufficient to cau.se the motors to begin to generate current when the electric-brake controller is first turned on. The greatest advantage of an cU'ctric l)rakc using motors as generators is in the fact that the braking current instantly falls in value as .soon as the wheels begin to .slide, and relea.ses the brake Kiir. 56. MiiiTUflii' Hraljc Slio until the wheels again revolve. In fact, it is almost imj^o.ssible to .skid the wheels as thev are sometimes skidded bv l)eing l;)cked bv brake .shoes. This not only prevents flat wheels ])ut insures a (juick .stop, because when the wheels are locked and .sliding, the braking or retarding power is only about one-third what it was before the wheels began to .slide. The electric brake requires extra large motors because of the lieating cau.sed by the current generated while braking. Westinghouse Electromagnetic Brake. The Westinghou.se magnetic brake is in ])rinciple similar to the (jencial I'lcclric brake as far as the use of motors as generators is concerned; but, instead of a.s.si.sting the motors l»y means of a magnetic l)rake di.sc acting again.st the car wlu'cl, a magnetic l)rake .shoe is u.sed (.see Fig. 50), which acts against both car wIhh'I and track. This not onlv retards en i< u & tn f-> Q Z < < K to Cd < u o H 6 cs o Z (s <^ i! < n f:: '- to 2 O § o .a ac ts S "^ cs z o S (A (< •<■ b: n Cd Z < UBRARY OF THE ii\;CR?. I'litMiiuulii' Sandfr. of controller during the change-over period when it is short-circuited, or in e(|uipments when the trolley flies oft' and the controller is turnel iu'irins to skid or slide, the coefficient of friction falls oft' about two-thirds. The maximum l)rakin,n' or re- tarding force that can l)e obtained, therefore, in a dry rail, amounts to 25 per cent of the weight of the cai-. If the rail is slippery this is much reduced; or if the wheels are allowed to slide it is also much reduced. If more retarding force than can be obtained through the medium of a wheel rolling on the rail is desired, it inust be obtained either by the track brakes or l^y magnetism. Fit- ^- .Automatic Coupler. Rate of Retardation in Braking. The rate of retardation of cars in l)raking is usually 1 to 2 miles per hour per second. In other words a car going at a speed of 40 miles an hour will usually be stopped in 40 to 20 seconds. The plotted results of some l)raking tests (Fig. 58) show a higher rate of acceleration. These tests were made on an interurban car weighing about 63,000 pounds, equipped with straight air brakes. Of the six curves shown, that giving the highest rate of retardation is No. 4. This shows a stop from a speed of 38 miles per hour in 9.^ seconds or a rate of retardation of about 4 miles per hour per second. All of the curves shown are for emergency stops. They show about the highest rate of retardation that could be made with the equipment. Drawbars and Couplers. For small surface cars a crude drawbar is usually provided consisting simply of a straight iron bar pivoted under the car and ])rovided with a cast-iron pocket near the end. A coupling pin passing through the pocket of one coupler and throuirh a hole in the end of the bar of the other, holds the two cars together. The requirements of a coupler for heavier cars such as those u.sed on interurban and elevated roads are more exacting. The ELECTRIC RAILWAYS 67 oikIs of the bars are usually pivoted un(ier tlie car about five feet back from the l>umper. A spring cushion intervenes between the ])ivot point an], the truck centers are but 21 feet S inches a])art, while the ends overhang the truck centers 11 feet 4i inches. It is difhcult to suj>port this overhanging weight properly. The difficulty is increa.sed by the fact that the rear platform is often crowded with pa.s.sengers having an aggregate weight of one ton oi- uKjre. Trusses manifestly ^rioor f a S "-S'xf Steel Place ■^1 "tf 1^ Fi^C. (>:). RfiufoiviiiL,' Plates. cannot be employed to give rigidity to the long platform. This is usually given in cars of wood construction l)y reinforcing the plat- form timbers with steel plates as shown in the figure. In order that the dropping tendency of the j^latfonn shall not bow up the body of the car between the trucks this portion must be braced rigidly, i'he space below the windows and above the side sill is iitili/.ed for this purpo.se. The .side sill is moreover .strengthened 1)V having .steel plates bolted to it. The longitudinal members of the body framing are termed sills. These are iLsually of long leaf yellow ])ine. A arious com- binations of wood and .steel are employed for sills, an example of which is .seen in Figs. (>1 and ()2. The sills are kept the ])roper distance apart by "bridgings" or cro.ss sills mortised into them at intervals and by "end sills." The whole framing is tied together by the rods rumiing parallel to the V^ridging. The.se tie rods are often ])rovidc(| with turn buckles for tightening when occasion mav recinirc. V ELECTKIC RAILWAYS 71 The outer sills are termed side sills; those nearest the center of the car, the center sills or draft timbers; while those between are called intermediate timbers. The remaining portion of the car is constructed much after the manner of a steam coach. The posts between the windows are mortised into the side sill at the bottom and into a top sill at their upper end. They arc laterally braced by a belt rail immediately under the window opening, both the belt rail and the posts being gained out so that the rail fits flush with the posts. A wide letter board gained into the post just below the side plate adds to the bra- cing of the side of the car, as does also an iron truss usually one-fourth to one-half inch thick and two to three inches wide which is gained into the posts on the inside running just under the windows between the truck centers, and then descends to pass through the side sills and fasten by a bolt underneath. The roof consists of the upper and lower decks. That portion over tlie platform or vestibule is termed the hood. Rigidity is given to the whole upper j)ortion of the car by the end ])lates resting on the corner posts and extending between the side plates at either end of the car body proper, and by steel carlins which conform to the pecuHar shape of the roof and extend between the side plates. I'he steel carlins are usually placed over alternate side posts. Bolted on either side of them and ])laced at intervals of about twelve inches between are wood carlins. The wood carlins of the lower deck extend ffom the side plate, to which they are fastened by screws, to the top sill, which is immediately below the windows of the upper deck. Above these windows is the top plate, supporting the carlins of the upper deck, which extend between and a few inches beyond the two top plates. Poplar sheathing three-eighths or one-half inch is nailed over carlins and on this heavy canvas usually of six or eight ounce duck is stretched tiglxtly. Several coats of heavy paint on the canvas and a trolley board for supporting the trolley stand complete the roof. On the underside of die carlins the headlining, usually of birch or birdseye maple, is .secured. '^Fhis forms the interior finish of the ceiling of the car. Steel Car Framing. As a result of the demands of the oflicials of the New York Subwav for cars of greater strength and less 72 ELECTRIC RAILWAYS sul)ject to danger from fire, much ])r()gress has been made in the last few years in the construction of cars with steel framing. Steel con- struction is much more expensive than that in which the framing is of wood and is considerably heavier. The advantages lie partly in the fact that it is more durable, but the great reason for the interest w ith which the new style of construction has been received is that the danger of collapse and consecpient injury to ])assengers, in case of accident, is greatly diminished. Car Weights. The total weight of a .street car with a body 1() feet long over corner ])o.sts mounted on a single truck with two motors is ap])roxiniately 14,000 pounds. Of this the body weighs about 4,000 pounds, the truck 4,400 pounds, and the inotors and the electrical e([ui])ment the remaining 5,100 pounds. The weights of the separate parts of a certain interurban car measuring 52 feet 6 inches over the bumpers mounted on double trucks, one of which carried two motors, is body 34,005, motor truck 9,565, ti'ail truck 6.670, electrical equipment 12,S00; total 63,100. An interurban car of about the same size as the one just men- tioned but e(|ui})ped with four motors gave the following weights: Body with controller and i-esistance grids 3!),()()() pounds, trucks 19,130 ])ounds, motors 15,420 poiuids; total 73,550 pounds. Car Painting. A great deal of attention is given to the proper painting of cars. A car ])ainted with care and proper materials always presents an attractive ap{)earan(e, while one carelessly j)ainted is reatlily noticealjle. New cars go tlirougli an elaborate painting process. The time recjuired is from two to three weeks. The fol- lowing scheme may he regarded as an example of a good process: A coat of primer is given the car tlie lirst day. Ou the thinl clay all irrej^ularities are puttied up smooth. Ou the fourth and fifth days a heavy primer is applied, one coat ou each day. A coat of tiller is gi\eu ou the sixth day and allowed to harden the following day. The next paint applied is termed a guide coat. This is of a color diflereut froui the pre- ceding ones and serves as a guide for tlie rubbers, wlio on the following day go over the ear with mineral wool, line saudpaj)er, or pumice stoue and rub it until the guide coat is worn away. This assures an even and smooth surface. Ou the tenth day the car is allowed to staiul. A coat of the color desired is aiiplied, one on each of the following tiiree (htys. Ou the fe Rail. A uioditication of the girder rail, known as the Trilhi/, and some- times a,s the grooved girder, is shown in Fig. 7(). A rail similar tt) this is used in several large cities of the United States. It has a groove of such a shape that the Hanges of the car wheels will force snow and dirt out of it instead of packing it into the bottom of the groove, as in the case of the regular European narrow- grooved rail. A narrow-grooved rail in which the grooves correspond closely to the sha})e of the car-wheel flanges is sure to make trouble in localities where there is snow and ice, as the grooves become packed and derail the cars. Shanghai T=Rail. Tn some systems :§|:Lzr;."7:$| a T-rail is used. Where the T-rail is to be used with ])aving, the popular form is the Shanghai T, .shown in Fig. 77. This rail is high enough to ])ennit the use of high jKiving blocks around it. I-'iK- "?•■ Girder Rail. Sireet Ry. Journal Fig. 76. Grooved Kail. ^^ Strctl Ky.Juurual Fin. 77 Shanghai T-Rail aud Joiut. Common T=Rail. The I'-rail u.sed by steam railroads is known as the A. S. ('. K. .standard T-rail, because it follows the standard ELECTRIC RAILWAYS 85 dimensions recommended for T-rails by the American Society of Civil Engineers. A standartl Go-pound T-rail of this kind is shown in Fig. 78. Other weights of this rail have the same relative pro- portions. Such a rail is used for interurban roads, and for suburban lines in streets where there is no block paving. The high rails are used to facilitnte paving with high paving blocks. Track Support. The greater portion of track is laid on wooden ties. These ties, in the most substantial wooden tie con- struction, are G inches bv 8 inches in section, and 8 feet lono;. Thev are spaced two feet between centers. Sometimes smaller ties, spaced farther apart, are used in cheaper forms of construction; but the foregoing figures are those of the best con- struction known in American railway practice. In paved streets, ties are usually employed, although sometimes what is known as "con- crete stringer" construction is used instead of. ties to support the rails. A strip of concrete about 12 inches deep is laid under each rail, and the rails are held to gauge by ties or tie rods placed at frequent intervals. Sometimes the concrete is made a continuous bed under the entire track. In most large cities the con- crete foundation is used under all paving; and consecjuently, when concrete is used instead of ties to support the rails, this concrete is simply a continuation of the paving foundation. Where ties are used, they are laid sometimes in gravel, crushed stone, or sand, although frequently, in the largest cities, they are embedded in concrete. Sometimes this concrete is extended under the ties, and sometimes it is simply put around the ties. Ballast. A ballast of gravel, broken stone, cinders, or other material which is self draining and which will pack to form a solid bed under the ties, should be used to get the best results under all forms of tie construction, wiiether in pavetl streets or on a [)rivate right of way, as pn an interurban road. Of course, if concrete is placed under the ties, the gravel or rock ballast is not necessary. If ties are placed directly in soft earth, which forms nnid when wet, they will work up and down under the weight of passing trains, and an insecure foundation For the track will i)e the result. t Ry.JuurL;i) Fig. 78. StiiiKliinl .V..S. C. E. Kuil iind Que Joint Platf. 86 ELECTRIC RAILWAYS Joints. The matter of securing a proper joint for fastening together the ends of rails so as to make a smooth riding track without appreciable jar or jolt when the wheels pass a joint, has iieen given much study hv electric railway engineers. A section through an ordinary bolted angle-V)ar joint is shown in Fig. 75. This joint is formed by bolting a couple of bars, one on each side of the rails. The edges of these bars are made accurately to such an angle that they will wedge in between the head and base of the rail as the bolts are tightened; hence the name angle bars. This is the form of joint generally used on steam railroads and on electric roads in exposed track, or in track where the joints are easily accessible, as in dirt streets. In paved streets, the undesirability of tearing up the pave- ment frecpiently to tighten the bolts on such joints, has led to the invention of several other tvpes, which will be described later. Never- theless very good results have been obtained in recent years with bolted joints laid in paved streets where care has been given to details in laying the track, and where the joints have been tightened several times before the paving is finally laid around them. Welded Joints. Several forms of welded joints are in use. All these welded joints fasten the ends of the rails together so that the rail is practically continuous— just as if there were no joints — so far as the running surface of the rail is concernetl. It was thought at one time that a continuous rail would l)e an impossibility because of the contraction ami expansion of the rail under heat and cold, which, it was thought, would tend to pull the rails apart in cold weather and to cause them to bend and buckle out of line in hot weather. Experience has conclusively shown, however, that con- traction and expansion are not to be feared when the track is laid in a street where it is covered with paving material or dirt. The paving tends to hold the track in line, and to protect it from extremes of heat and cold. The reason that contraction and expansion do not work havoc on track with welded joints, is probably that the rails have enough elasticity to provide for the contraction and expan- sion without breaking. It is found that the best results are secured by welding rail joints during cool weather, so that the effect of contraction in the coldest weather will be niininuuu. In this case, of course, there will be consideral)le expansion of the track in the hottest weather, en < < H U H b O H o n hj u I H U) < U o b < O P-. U U « <; H CC O UBRARY Of THE jNIVERSffY of lUiN^' ELECTRIC RAILWAYS 87 but this does not cause serious bending of the rails; whereas occa- sionally, if the track is welded in very hot weather, the contraction in winter will cause the joint to break. Cast=Welded Joints. The process of cast-welding joints con- sists in pouring very hot cast iron into a mould placed around the ends of the rails. These moulds are of iron; and to prevent their sticking to the joint when it is cast, they are painted inside with a mixture of linseed oil and graphite. Iron is usually poured so hot that, before it cools, the base of the rail in the center of the molten joint becomes partially melted, thus causing a true union of the steel rail and cast-iron joint. This makes the joint solid mechanically and a good electrical conductor. To supply melted cast iron during Fig. 79. Process of Cast-Welding Joint. the process of cast-welding joints on the street, a small portable cupola on wheels is employed. Fig. 79 gives an idea of the process of making cast-welded joints. Electrically Welded Joints. An electrically welded joint is made l)y welding steel blocks to the rail ends. A steel block is placed on each side of the joint, and current of very large volume is passed through from one block to the other. This current is so large that the electrical resistance between the rail and steel block causes that point to become molten. Current is then shut off, and the joint allowed to cool. There is in this case a true wekl between the .steel blocks and the rails and joint. 88 ELECTRIC KAIL WAYS An electric welding outfit i)eing expensive to maintain and operate, this process is used only where a large anioinit of ^-elding can be done at once. Current is taken from the trolley wire. A rotarv converter set takes oOO-volt direct current from the trolley wire, and' converts it into alternating current. This alternating current is taken to a static transformer v.hich reduces the voltage and gives a current of great (juantity at low voltage, the latter cur- rent being passed through the blocks and rails in the welding proc- ess. A mas.sive pair of clamps is used to hold the blocks against the rails, and to conduct the current to and from the joint while it is being welded. These clamps are water-cooled by having water circulated through them .so that they will not become overheated at the point of contact with the steel blocks. Thermit Welding. A process of welding rail joints which"* was developed after the cast-welding and electric-welding processes, is known as the Goldschmidi process, which makes use of a material called "thermit" for supplying heat to make the weld. A mould is placed around the joint and the thermit is put in this moukl and ignited. The heat produced by the thermit is so intense as to reduce the iron in the thermit mixture and make a welded joint. The thermit consists of a mixture of finely powdered aluminum and iron oxide. ^Yhen this is ignited, the aluminum oxidizes, that is, alxsorbs oxygen so rapidly that an intense heat is the result. In the process of oxidation, the aluminum takes the oxygen from the oxide of iron, leaving molten metallic iron, which metallic iron makes the weld by union w^ith the molten rail ends. This process has the advantage over other welding processes, of not requiring an elaborate apparatus and a large crew of men to operate it; and consequently it can be used where but a few joints are to be welded. Bonding and Return Circuits. When the track ra'ls are used as the conductors, as is usually the case, it is necessary to see that the electrical conductivity of the rail joints does not offer too high a resi.stance to the passage of the current. For this reason, when bolted or angle-bar joints are used, the rails are bonded together by means of copper bonds. It was soon found after electric roads were in use a short time, that unless the rail ends were so bonded, the resistance of the joints was so great as to cAuse great loss of power in the track. First, small iron bonds were used; but these l)()nds ELECTRIC RAILWAYS 89 were so insufficient that large copper-wire bonds soon began to be use;! ; and at the present time, on large roads, bonds of heavy copper cable ai'c common. The resistance of a steel rail, such as used in city streets,- is about eleven times that of copper. In order to secure as great carrying capacity at the rail joint as is afforded l)y the un- broken rail, it is therefore necessary to install bonds having a total cross-section j\ that of the rail. Where welded joints are used, bond- ing is unnecessary, except at crossings and switches where l)olted joints are employed. Where track is welded, however, cross bonds should be put in at frecjuent intervals from one rail to another, and, if the track is double, from one track to the other, so that if one of the track rails breaks at a joint there will be a path around the break for the current. Copper Wire ~Channe/ Pin Fig. W). C'lmnuel Piu Boud. L i--*i I I a ^^\\y!;^\;i^^^^^ Fig. 81. Chicago Rail Bond. A great many schemes have been devised to insiu'e good con- tact between the copper bond and the rail, as the terminal is the weak point in anv bond. One of the earliest and most efficient of .small bonds was made by the use of channel pins, Fig. SO. This bond consisted of a piece of copper wire having its ends placed in the holes in the rail ends. Alongside this wire, a channel pin was driven in. The objection to the channel pin was the small area of contact between the copper l)ond and rail. Next after the channel pin came the Chicago type of bond, Fig. ,S1, which is a jMece of heavy copper wire with thimbles forged on the ends. These tliimbles were placed in accurately fitted holes Fig. 83. Kail Bond. •M^ ELECTRIC RAILWAYS ill the I'ail (.'inlN, iiiid :i wcdj^r-sliiijjrd steel j)iii was n Total drop in rail Drop in trol- ley Drop in feed- er Resistance feeder Feet per olina 72.53 Size of wire.. No. 1 3.1 Volts 3.1 " 20.5 " 36. 1 " .728 Ohms lies -«+« — / Miie n ^ -a Miles- e Miles - Fig. 84. 2.1 Volts 1.05 Volts .5.2 " 6.25 " 20.5 " 20.5 " '34.3 " 33.25 " .686 Ohms 23000 2.50.U00 C. M. .6&5 OJmis 39700 420.000 C. U. The following example will show the method pursued. The figures resulting from the calculations are placed immediately below the sections to which they refer in Fig. 84. The rails are assumed to be 70 pound to the yard. These have a resistance of about .018 ohms per mile. Adding one-sixth for additional resistance of bonds gives .021 and since the track is composed of two rails the resistance of the track will be one half of this or .0105 ohms per mile. The maximum drop in any section occurs when the car is farthest from the power house. Each car is assumed to take 50 amperes and the feeders are to be so designed as to allow a 10 per cent or 60 volts drop. The current in the two miles of track nearest the power house is l.')0 amperes, in the next section 100 amperes, and in the last .section 50 amperes. The'dropin each section is as shown. The drop in the trolley which is 00 wire is, in each section, 20.5 volts. Subtracting 94 ELECTRIC RAILWAYS from 00 volts the drop in tlie return circuit and trolley, gives the allowahle drop in the feeder. Tlie resistance of each feeder can l)e calculated, since the current in each one is 50 amperes. The first feetler is one mile long, the second 3 miles and the third 5 miles, and with these figures the feet per ohm can be computed. The size of wire may be obtained by reference to a table of copper wire resistances. BLOCK SIGNALS FOR ELECTRIC RAILWAYS. The simplest block signal used by electric roads is a hand- operated one constructed on the principle shown in the diagram Fig. 85. A double throw switch is placed at each terminal of the section of track that is to be protected. Tro//ey LgmfiS LarPfs T Ground Fig. 85. Crouna o ■4 The switches have no central position, the knife blade always making contact with one or the other of the terminals shown. If the lamps are lighted, throwing either one of the switches w'ill put them out. If they are not burning, they will be lighted by throwing either one of the switches. A motorman on reaching a section of track finding the lamps not burning throws the switch. Lamps now burn in each switch box and show that the section is in use. On arriving at the other terminal of the block the switch is thrown, extinguishing the lights and showing that the block is clear. Automatic signal systems have been devised on the same prin- ciple, in which magnets, operated by contacts made by the passage of the trolley wheel, cause the lamps to be lighted and extinguished automaticallv. ELECTRIC RAILWAYS 95 ELECTROLYSIS. Muoh has been said about the possibiHties of electrolysis of uiKlergroiind metal by the action of the return current of electric railways, when such railways are operated with grounded circuits, as they usually are. If electric current is passed through a licpiid from one metal electrode to another, electrolysis will take place; that is, metal will be deposited on the negative pole, and the posi- tive pole or electrode will be dissolved by becoming oxidized from the action of the oxygen collecting at that pole. In an electric-railway retm-n circuit, there is necessarily a dif- ference of potential l)etween the rails at outlying parts of the system and the rails and other buried pieces of metal located near the power . < .. Tro/fey //n e ^^^ DDDDDI 1 Track Fig. 86. Showing Electrolytic Action. house. Just what this total difference of potential is, depends on the loss of voltage in the return circuit. Thus, suppose there is 25 volts drop in the return circuit between a certain point on the system and the power station. There is, therefore, a pressure of 25 volts tending to force the current through the moist earth from the rails at distant portions of the line, to the rails, water pipes, and other connected metaUic structures located in the earth near the power station. The amount of current that will thus flow to earth in pref- erence to remaining in the rails, depends on the relative resistance of the rails, the earth, and the other paths offered to the current to return to the power house. To take a very simple case, let us suppose a single-track road, Fig. 86, with a power house at one end, and a parallel line of water pipe on the same street passing the power house. If the positive terminals of the generators are connected to the trolley wire, the current passes, as indicated by the arrows, out over the trolley wire through the cars and to the rails. When it has reached the rails 1)0 ELECTRIC RAILWAYS it has the choice of two paths back to tlie power house. One is tlirough tlie rails and boncHng; the other is through the moist earth to the hne of water pipe and hack to tlie power house, leaving the pipe for the rails, at the power house. Should the bonding of the rails be very defective, consideral)le current might pass through the earth to the water pipe. Remembering now the principles of electrolysis, we see that the oxidizing action of this flow of current from the rails to the water pipes at the distant portion of the road will tend to destroy the rails, but will not harm the water pipe at that point, as it will tend to deposit metal upon it. ^Yhen, however, the current arrives at the power house, it must in some way leave this water pipe to get back to the rails, and so to the negative terminals of the generators. Here we see that there is a chance for electrolysis of the water pipe, because at this point the water pipe forms the positive elec- trode, which is the one likely to be oxidized and destroyed. This very simple case is taken merely for illustration. In actual prac- tice the conditions are never so simple as this, for there are various pipes located in the ground running in various directions, which complicate the case very much; l)ut we can see from this simple example that the principal place electrolysis of water pipe is to be feared is at points where a large volume of current is leaving the water pipe to take to some other conductor. As an indication of how much current is likely to be leaving the water pipes at various points, it is customary to measure the voltage between the water pipes and the electric railway track and rails. When this voltage is high, it does not necessarily mean that a large volume of current is leaving the water pipes at the point where these pipes are several volts positive with reference to the rails; but such voltage readings indicate that, if there is a path of sufficiently low resistance through the earth, and if the moisture in the earth is sufficiently impregnated with salts or acids, there will be trouble from an electrolytic action due to a large flow of current. There is obv-iously no method of measuring exactly the amount of current leaving a water pipe at any given point, since the pipe is buried in the earth. A'oltmeter reatlings between pipes and rails simply serve to give an indication as to where there is likely to be trouble from electrolysis. The danger to underground pipes and ELECTRIC liAILWAYS 97 other metallic structures from electrolysis has been much over- estimated by some people, as the trouJ)le can be overcome by proper care and attention to the return circuit. Trouble from electrolysis, however, is sure to occur unless such care is given. Prevention of Electrolysis. Remedies for electrolysis may be classified under two heads — general and specific. The general remedy is obviously to make the resistance of the circuit through the rails and supplementary i-eturn feeders so low that there will be but little tendency for the current to seek other conductors, such as water and gas pipes and the lead covering of underground cables. This remedy consists in heavy bonding, in ample connections, around switches and special work where the bonding is especially liable to injury, and in additional return conductors at points near the power house to supplement the conductivity of the rails. It is important that all rail bonds be tested at intervals of six months to one year in order that defective bonds may be located and renewed, as a few defective bonds can greatly lower the efficiency of an otherwise low-resistance circuit. The specific remedy for electrolysis which may be ap])lied to reduce electrolytic action at certain specific points, consists in con- necting the water pipe at the point where electrolysis is taking place, with the rail or other conductor to which the current is flowing. Thus, for example, if it is found that a large amount of current is leaving a water pipe and flowing to the rails or to the negative return feeders at the power house, the electrolytic action at this point can obviously be stopped by connecting the water pipe with the rails by means of a low-resistance copper wire or cable, thereby short- circuiting the points between which electrolytic action is taking place. There are certain cases in which it is advisable to adopt such a specific remedy. It should be remembered, however, that a low-resistance connection of this kind, while it reduces electrolysis at points near the power house, is an added inducement to the ciu*rent to take to the water pipes at points distant from the power house, because of the decrease in resistance of the water-pipe path to tb.e power house resulting from the introduction of the connection between the water pipe and the negative return feeder at the power house. With the water pipes connected to the return feeders in the vicinity of the power house, the current which flows from the rails to the water 98 ELECTKIC KAILWAYS ])ij)e.s at points distant from tlie j)o\ver house will ohviously cause electrolysis of the rails but not of the water pipes, since th.e ciuTent is passinor from the earth to the pipe, antl the pipe is ne<;ative to the earth. In this case the principal (lano:er is that the high resistance of the joints between the lengths of water pipe will cause current to fiow through the earth around each joint, as indicated on some of the joints, Fig. 86, and will cause electrolytic action at each joint. It is evident, however, that the conditions of the track circuit and bonding must be very bad if current would flow over a line of water j)ipe, with its high-resistance joints, in sufficient volume to cause electrolysis, in preference to the rail-return circuit, especially since ordinarily the resistance offered to the flow of current over the water pipes back to the power house must include the resistance of the earth between the tracks and water pipes. It is usuallv considered inadvisable to connect tracks and water pi])es at points distant from the power' house, because of the danger of electrolysis at water-pipe joints, as just explained. IMethods of testing rail bonds in the track will be explained luider the head of "Tests." POWER SUPPLY AND DISTRIBUTION. Direct=Current Feeding. As already explained, the majority of electric railways are operated on a .')()0-volt constant-potential direct-current system with a ground return. A constant potential of 450 to .550 volts is maintained between the trolley wire and track. Where the trolley wire is not sufficient, additional feeders are run from the power house and connected to the trolley wire, the number V of feeders depending on the distance from the power house and the traffic. Booster Feeding. Boosters are sometimes used on long feeder lines where there is a heavy load only a small portion of the time. These boosters are direct-current dMiamos that are con- nected in series with the feeder upon which the voltage is to be raised above the regular power-house voltage. The booster may be driven either by a small steam engine or by an electric motor. The simplest form of booster is a series-wound dynamo. A booster armature must, of course, be of sufficient current capacity to pass iill the current that will be required on its feeder. The voltage ELECTRIC RAILWAYS 99 yielded by this dynamo, plus the power-station voltage, is the voltage of the boosted feeder as it leaves the power house. Supposing that a series-wound booster will give 125 volts at full load; it is obvious that being series-wound it will give no voltage at no load. The voltage will increase approximately as the load on the feeder increases; and since the drop in voltage on the feeder for which the booster is to compensate also varies with the load, the action of the booster is simply to add sufficient voltage to its feeder at any instant to com- pensate for the line loss upon that feeder and to maintain approxi- mately constant potential at the far end of the feeder. Boosters raising the power-station voltage of a feeder more than 250 volts above the normal power-station voltage, are not common, though cases are on record where a feeder has been boosted as high as 1,100 volts above the power-station voltage. Since all the power used in driving a booster is wasted in line loss, this method of feeding is not economical; but where used only a few days out of the year it is sometimes to be preferred to a heavy investment in feeders. The investment in feeders might involve more interest charges than the cost of power wasted in booster feeding would amount to. Alternating=Current Transmission. High-tension alternat- ing-current transmission to substations, with direct-current dis- tribution from, substations, is extensively used on long interurban roads, and on large city street-railway systems w^here power is to be distributed over a wide area. In such cases the power house is equipped with alternating-current dynamos supplying high-tension three-phase alternating current to high-tension transmission lines or feeders. These high-tension feeders are taken to substations located at various points on the road, where the voltage is reduced by step-down transformers; and these transformers supply current to operate rotary converters, which convert from alternating to direct current for use on the trolley. The advantage of this system of high-tension distribution is that, owing to the high transmission voltage, there is but a small loss in the high-tension lines, which lines can be made very small, and will thus involve but little copper investment. The substations can be located at- frequent intervals, so that the distance the 500-volt direct-curreitt must be conducted to supply the cars is not great. Current from one power house can thus be distributed over a very 100 ELECTRIC RAILWAYS larere system in cases where, if the oOO-voU (hrect-ciirrent system of (hstribution \yere used, the cost of feeders for distributing such a h)^v-yoltage current would be prohibitiye. AVere the ahernating-cur- rent high-tension scheme of distribution not used, it would be neces- Higf^ Tensiort D. c. Feec/er- ifA/RMOUNT Broad - /Nipple. /NOMf^APOLIS Fig. 87. Diagram of Distributing Sj'stem. sary to haye a number of small power houses at yarious points on the system instead of one large power house. The cost of operation of seyeral small power plants per kilowatt output, is likely to be much greater than that of one large power plant. The first cost of the alternating-current distributing system, including power house Ei^ECTRIC RAILWAYS. 101 and substations, is likely to be considerably higher than would be the cost of a number of small power houses; but in cases where alter- nating-current distribution has been installed, it has been figured that the cost of operation of the central power house with alternating- current distribution would be sufficiently low as compared with several small ones to pay more than the interest on this extra invest- ment. A System of Distribution for an Interurban Railway. The typical features of a high tension system of distribution for an extensive interurban railway system are shown in Fig. S7, which represents the electrical transmission and distribution system of the Indiana Union Traction Company. The central power station at Anderson feeds into thirteen rotary converter substations from 7 to 65 miles distant from the power house. The substations east of Indianapolis are fed at 16,000 volts and are placed about 11 miles apart. The substations due north of Indianapolis are located at intervals of about 17 miles and are fed at 30,000 volts. The power station at Anderson has a total capacity of 5,000 K. V\ . The substations vary in capacity from 250 to 1 ,500 K. W. Efficiency of Transmission Systems. The average efficiency of a high tension transmission system for a certain interurban electric railway system are given below. Current was generated at 380 volts. The step-up transformers raised it to a potential of 16,000 volts at which pressure it was transmitted to eight substations at distances from 10 to 40 miles from the power station. It was then stepped down to 380 volts and converted to direct current by a rotary converter. The tests extended over a period of three days. The efficiency of the step-up transformers was 95 per cent; of the high tension line 92.9 per cent; of the step-down transformers 95 per cent; and of the rotary converters 88 per cent; giving a total efficiency of the transmission system of 73.5 per cent. Power House Location. A power house is usually located where coal and water supply can be cheaply obtained. For this reason it is placed either on some line of railroad or where coal can. be taken to it over the electric railwav. As it is always desirable to operate the engines in connection with condensers, on account of the saving in fuel, which is approx- imately 20 per cent with condensers, power stations are located, 102 ELECTRIC RAILWAYS when possible, near rivers and ponds from which a large supj/ly of cold water for condensation of exhaust steam can be obtained. Where no such natural water supply is available, it has become customary to provide means for artificially coolino- a sufficiently large supplv of water for condensation. One method is to erect a numijer of towers, so constructed that the water when pimiped to the top will fall through a structure that breaks the water up into fine spray as it falls, thus alU)wing it to cool by evaporation so that it can be used again for the condensers when it arrives at the bottom of the tower. AVhere more room is a^•ailable, ponds are sometimes excavated near the power house, and the water is made to flow back and forth through a series of troughs located above the pond, and it is thus cooled^ Where a power station is of the direct-current type, operating at 500 to 600 volts, it is desirable to have it as near the center of electrical distribution as possible, in order to keep down the amount of investment in the feed wire; but it is more important to have it located near a cheap coal and water supply than exactly at the center of distribution. It is also desirable to have the station located where there is room for coal storage, on account of the dmnces for interruption of the coal supply by strikes, railroad blockades, and other causes beyond the company's control. The continuity of the coal supply is also another argument against placing the station where depend- ence must be placed upon wagons or inadeciuate railroad facilities. Coal handling, after the coal has reached the station, is done bv hand in the smaller power stations; but in larger power stations it lias come to be the general practice to do as much of the handling as possible by means of automatic coal conveyors. The most elab- orate power stations have means for dumping coal from cars into hoppers, from whic-h it is conveyed by an endless chain provided with buckets, called a coal conveyor, to storage bins. Coal conveyors also take the coal from the storage bins, aiul deposit it in the hoppers of mechanical stokers in front of the boilers. Ashes are conveyed from under the boilers by the s?>me kind of conveyors, and are dumped into hoppers, whence they are drawn into cars or wagons to ))e hauled away. ELECTRIC KAILWAYS 103 The coal, having been deposited in hoppers at the boiler front, is autoniaticallv fed into the furnaces by automatic stokers. One t\^)e of automatic stoker in common use is of the chain-grate or link-belt type, which is constructed like an endless sprocket chain, with links composed of heavy cast-iron blocks that serve as grate baj's. This link belt or chain is kept in constant, slow motion by a small stoker engine or motor which operates all the stokers of a line of boilers. The coal is fed from the hopper on to the chain jjrate, and the chain is slowly moved under the boilers. As the coal on that part of the grate imder the boilers is on fire, the fresh coal as it enters the furnaces is soon ignited. The grate is run at such a rate, and the thickness of the coal is so adjusted, that the coal is burned to an ash bv the time it has traveled to the back of the furnace. There the grate turns down over a sprocket wheel, and the ashes are dumped into the ash pit as the grate revolves. The boilers in most common use in large American electric- railway power houses are of the water-tube - type, in which water is contained inside of a bank of tubes, the ends of these tubes being connected to drums or headers. The horizontal return-tubular type of boiler is used in many of the smaller power stations, and verti- cal boilers are also in use. The engines in the larger and more economical stations are generally of the Corliss compound-condensing type, running at speeds of from 60 to 120 revolutions per minute, according to the size of the unit. The smaller the unit, the higher the speed. In the smaller and older stations, simple Corliss engines belted to generators are frequently found, and high-speed engines also are '.ised. It is the almost universal custom now, to place the generator ilirectly on the engine shaft, making a direct-connected luiit. Steam turbines, in which the steam acts in jets against the blades of a turbine wheel, are beginning to come into use at the ])i-esent time. These turbines rotate at very high speed, the largest and slowest speed-units running 600 r.p.m., and others at higher rates. As the output of any generator varies directly according to its speed, a very much smaller generator can be used when coupled to a high-speed steam turbine, to obtain a given output, than if the generator must be coupled to a Corliss steam engine which revolves at very low speed. The economy of the steam turbine at full load IQi ELECTRIC RAILWAYS is about that of a compoiind-coiulensing Corliss engine, but is better on light loads than the engine. Thcv turbine requires less building space and a much less expensive foundation. Railway generators or dynamos for direct current are usually built with compound-woimd fields, so that, as tlie load increases, I 2 I i ^y/yyyyyyyyy^ w/^^y^^y>^//^y>j^/A w//////// ;^7Z7 m>////////////// A BO/LER BO/LfTR CO BO/LER Bo/LER art I y/////////A y////////////^ / A Y /////////// ///// ^//{////?Z'^7m' Fig. 88. Phm of P.nvei- House. thev will automatically raise the voltai-e at their terminals to com- pensate for the drop in the feeders and to maintain a constant poten- tial at the cars. Thus, if the line loss on a system is 10 per cent, or 50 volts at full load, the generators will be provided with shunt fiekls of sufficient strength to give 500 volts at no load, and with series field coils wliich will add to the field strength enough to give 550 volts at full load. The amount of "compounding" — which is the ELECTRIC RAILWAYS 105 term applied to this method of increasing voltage — may be any amount within reasonable limits. The pressin-e maintained at difierent companies' electric-railway power houses varies, but is usuallv ])etween 500 and GOO volts. AIternating=Current Generators. Alternating-current gen- erators used for generating alternating current to be distributed at high tension, are generally constructed to give a three-phase cur- rent at 25 cycles per second. Th6 voltage of these alternating- current generators is sometimes the voltage at which the power is to be transmitted, if the distances are not too great. A number of stations have alternating-current generators giving 6,600 volts at their terminals, which is a voltage well adapted to high-tension distribution within the limits of a large city. However, genera- tors giving 11,000 volts at their terminals are now becoming com- mon. For higher voltages than this, it is considered necessary to use step-up transformers, in order to raise the voltage to the proper pressure for transmission over long distances. In such cases there is no object in having a high generator voltage. At such stations the voltage of the generators adopted may be anything desired, and it varies according to the ideas of the constructing engineer. Voltages of 400, 1,000, and 2,.300 are among those in most com- mon use. Double=Current Generators. Double-current generators are sometimes used, which generators will give direct current at a commutator at one end of the armature for use on a 500-volt direct- current distribution system supplying the trolley direct. The other end of the armature has collector rings from which the three-phase alternating current is obtained, which can be taken to step-up trans- formers and raised to a sufficient pressure for high-tension transmis- sion to substations at distant parts of the road. The same generator can therefore be used on both the direct-current and the high-tension alternating-current distribution. General Plan of Power Stations. The general plan of an electric-railway power station is usually such that the building can be extended and more boilers, engines and generators added without . > •(-I &4 the same as that on the bus bars. The voltages on the bus bars and on the new generator are measured nsually by a large voltmeter on a bracket at tlie end of the generator switchboard. By means of a voltmeter plug ov of a push button on the generator panel, the volt- 110 ELECTKir ^^UL\VAYS iDoter can !)«• coiiiiected t'itluT to the l)U.s l)ars or to the new eing in phase, the actual energy consumed is small. lU ELECTRIC KAIL WAYS Single-Phase Motors, llie Westin^house Electric eed on a level, is evidently the tractive effort in pounds multiplied by the speed in feet per minute and divided by 33,000. What the tractive effort per ton of car will be, depends on the condition of the rail and on several other imcertain factors. For street-railway motor cars, 20 pounds })er ton is the usual tractive effort assumed as necessary. A calculation of this kind, iiowever, takes no account of the losses in the motors and gears, nor of the fact that the greater part of the power rc(|iiiie(l to ])ropel a street car iu practical service is used in accelerating the car from a state of rest to full speeil. In 116 ELECTRIC RAILWAYS 0) 9 c to oi s-j d r ^ ^ / ^ O u o 5! ^ 39 y/noA ac \l- >XOI «i - ._. —' • .__ / o fe -1 o / / f / o o— r -§- 1 Is (0 jr o , 1 \ \ § \ s I' "0 >0 o 8 s To 15^ TON CAR MCTTORS CONDS / o ;i O 1 ] o 8- 1 a: "cu — { {VES FOR 325 .HOUSE N0"b" STOP 15 SE , ' \ \ L o 1 b a — (0 F > s CM V f ^ I. fl. O 1 5 1 .0 o P 0) p. 9 !? r (I) 1 1 oj^ ^ 4 — / 9 1 o s- 1 2^ ia-7 / S| b Q. a (0 lil / , c o / / w ' §1 - d ° v A / o J / \ / o < ^ Y \ V =^ c o \ V \ J \ ^ 10 I^J i\ i!. ■? ^ ? y '-< h L^ ?:' \x c :> % ^ — bN 1^ f < ,car 3// -3ff. Fig. 94. Bond Testing. sary amount of resistance into the return circuits. One way of doing this is to measure the drop in ])otential over a bonded joint as compared with the droj) in potential of an ecpial length of unbroken rail. To do this, an apj)aratus is em])l()yed wherein' sinudtaneous contact will be made bridging three or more feet of rail and an ecjual length of rail including the bonded joint, as shown in Fig. 1)4, which illustrates the connections of a conmion form of apparatus where two milli-voltmeters are employed that measure the drop in voltage of the bonded and unbonded rail simultaneously. If the current flowing through the rail due to the operation of the cars were con.stant, of course one milli-voltmeter might l)e used, being connected first to one circuit and then to the other. The current in the rail, however, fluctuates rapidly, so that two instruments are necessary for rapid work. The resistance of the boiKh'd joint is usually considerably more tliaii tliat-of ti:e unbroken rail, and the niilli-voltmeter u.sed to ELECTIUC RAILWAYS 121 bridge the joint consequently need not be so sensitive as that bridgin^^ the unbroken rail. In another form of apparatus, a telephone receiver is used in- stead of the milli-voltmeter, the resistance of a long unbroken rail being ])alanced against that of the bonded joint, as in a Wheat- ^ stone bridge, until, upon closing the circuit, these two resistances A\hen balanced give no sound in the telephone receiver. Bond tests of this kind can be made with satisfaction oftly \-ihen a considerable volume of current is flowing through the rails at the time of the test, })ecause the drop in voltage is dependent (m the current flowing, and in any event is small. It has some- times been found necessary or advisable to fit up a testing car ecjuipped with a rheostat which will itself use a considerable volume of current, so as to give a current in the rail which will give an appreciable drop of potential across a bonded joint. Some of the latest forms of testing cars carry motor generators which will pass a large current of known value through a bonded joint, and so cause a drop of potential across the joint large enough to be easily measured. notor=Coil Testing. Testing for faults in the motor armature and field coils is done in a great variety of ways. The resistance of these coils can be measured by means of a Wheatstone bridge employing a telephone receiver in place of the galvanometer used in such bridges in laboratory practice; but other less delicate tests are also in use. Another method is to pass a known current through the coil to be tested and to measure the drop in the voltage between the terminals of the coil, the voltage divided by the current efjualing the resistance. A simple method, and (me which involves no delicate instru- ments, has lately been introduced into railway shop practice very successfully. This is known as the tranfiformer test for short-circuited coils. It requires an alternating current which can easily be supplied either by a regular motor generator or by putting collecting rings onto an ordinary direct-current motor and connecting these rings to bars of opposite polarity on the commutator. The method of testing for short-circuited armature coils em- ployed in the shops of the St. Louis Transit Company is indicated in diagram in Fig. 95. A core built up of soft laminated iron is \22 ELECTKIC KAILWAVS wound with 2S turns of No. (> copper wiic. This coil is supphed with alternatini>; current from a llO-voU circuit. The core has jiolc pieces made to ht the surface of tiie armature. ^Vhen {)ne side of a short-circuited coil in the arinatuie is hroufi^ht l)etween the pole pieces of this testin<^ transformer, as in Fig. Oo, the short- circuited armature coil becomes like the short-circuited secondary of a transformer, and a laro;e current will flow m it. This current will in time manifest itself bv heatiufj the coil; but it is not nece.s.sarv to wait for this, as a piece of iron held over that .side of the coil not enclo.sed between the pole pieces, as indicated in Fi, ELECTRIC RAILWAYS 121 Fig. 97 order to replace one coil alone, one-fourth of the coils of the arma- ture must be lifted. With the armature of No. 1 motor grounded the car will not operate and if the resistance points he passed over, the fuse will usually blow. When No. 2 motor is grounded the action of No. 1 motor is not im- paired and this latter motor will pull the car until the controller is thrown to the multiple position. But if the motors are thrown in multiple, the path through the ground of No. 2 motor shunts motor No. 1. A, study of Fig. IS will make this evident. Next to grounding, open circuits are the most serious defects of armatiu'es. These are usuallv caused bv burning in two of the wires in the slot, or where they cross one another in passing to the commutator. Some- times the connections where the leads are soldered to the commutator become loose. The effect of an open circuit is shown in Fig. 9(). The circuit is open at n. The brushes are on seg- ments a and d. By tracing out the winding it will be found that no current flows through the wires marked in heavy lines. Whenever segments c and d are under a brush the coil with the open Fig. 98. 126 ELECTRIC RAILWAYS circuit is bridtfcd by the brush and current flows as in a normal armature. As segment c passes out from under tlie Imish the open circuit interrupts the current in half the armature and a long flaming arc is drawn out. In Fig. 07 is shov\n the result of a short circuit between two coils. The short circuit is at h, c, the two leads coming in contact with each other when they cross. The efi'ect is to short-circuit all of the winding indicated by the heavy lines. Mistakes in Winding Armatures. The armature winder is given very simple rules as to how to wind the arma'ture, but the great number of leads each to be connected to their proper commutator segment sometimes so confuse him that misconnections are made. The efl'ect of getting two leads crossed is shown in Fig. 98. The leads to segments /; and c from the right are shown interchanged This short- circuits the coils shown in heavy lines. The abnormal current resulting in these would iisuallv cause them to burn out. Fig. 00 shows the results of placing all of the top leads or all of the bottom leads one segment beyond the proper position. This causes the circuit starting from a and traveling coun- ter clockwise aroimd the armature to return on segment m instead of on segment h as is the case in Fig. Fig. 99. 97. The only result of such connections is to change the direction of rotation of the armature. It may be noticed by comparing the two figures that with the positive brush on segments a the arrows show the currents to be in opposite directions in coils similarly located with reference to the position of the brushes Some armatures are intended to be wound as in the last case mentioned. ELECTKIC RAILWAYS 127 Sparking at the Commutator. As railway motors are made to operate, and usually do oj)erate, almost sparklessly, sparking at the brushes may be taken as a sign that something is radically wrong. The pressure exerted by the spring in the brush holder may not hold the brush firmly against the conmiutator. If brushes are burned or broken so that they do not make good contact on the commutator, they should be renewed or should be sandpapered to fit the commutator. A dirty commutator will cause sparking. A commutator having uneven surface will cause sparking, and should be polished off or turned down. Sometimes the mica segments between commutator bars do not wear as fast as the bars and when this is the case, the brushes will be kept from making good contact when the commutator bars are slightly worn. . The remedy is to take the arm- ature into the shop, and groove out the mica between the commutator bars for a depth of about ^^j-inch be- low the commutator surface. A greenish flash which appears to run around the commutator, accompanied pig. loo. by scoring or burning of the commutator at two points, indicates that there is an open-circuited coil at the points at which the scoring occurs as in Fig. 100. The magnetic field may be weakened by a short circuit in the field coils, as before explained, and this may give rise to sparking. Short circuits in the armature may give rise to sparking, but will also be made evident by the jerking motion of the car and the blowing out of the fuse. Failure of Car to Start. The failure of the car to start when the controller is turned on may be due to any of the following causes : 128 ELECTRIC RAILWAYS Opening of the circuit breaker at the power house: Poor contact between the wheels and the rails owing to dirt or to a breaking of the l)ond wire (vnnections l)etween the rail on which the car is standing and the adjacent track. One controller may be defective in that one of the contact fingers may not make connection with the drum. In this case try the other controller if there is another one on the car. The fuse may be blown or the circuit breaker opened. The occurrence of either of these, however, is usually accompanied by a report which leaves little doubt as to the cause of the interruption in current. The lamp circuit is always at hand for testing the presence of current on the trolley wire or third rail. If the lamps light when the lamp circuit is turned on, it is a tolerably sure sign that any defect is somewhere in the controllers, motors, or fuse boxes, although in case the cars are on a very dirty rail enough current might leak through the dirt to light the lamps, but not sufficient to operate the cars. In such a case, the lamps will immediately go out as soon as the controller is turned on. Ice on the trolley wire or third rail will have the .same efli'ect as dirt on the tracks. LOCATING DEFECTS IN MOTOR AND CONTROLLER WIRING. Defects in the wirings are those due to (1) open circuits, (2) sliort circuits. Open circuits make themselves evident by no flow of current, short circuits usually by a blowing of the fuse or opening of the breaker. The point of the short circuit or "ground" can be located roughly by noting on what point the fuse is blown. Accurate location can be made by cutting out the motors, disconnecting, otc, according to directions in the following pages. The tests outlined apply particularly to the K type of controller with two-motor equip- ment. OPEN=CIRCUIT TESTS. No current: On 1st point, Open circuit but not located. On 1st point multiple, Motors most probably O. K. ELECTRIC KAILWAYS 12U On series-resistance points after trying 1st point multiple, Open circuit outside controller and equipment wiring. ^Yith an open anywhere between trolley and ground no current will flow on the first point. Opens are most likely to occur in the motors and these may be tested first. However, as will be explained later, one open in an armature will not stop the current. To test the motors open the breaker and put the controller on the first point multiple. Then flash the l)reaker cjuickly. Current flowing indi- cates that one or the other of the motors has an open circuit. In the series position this open prevented the flow but in multiple the current flows through the other motor. "Which one is at fault can be quickly determined by returning the controller to the off position and cutting out one or the other of the motors by means of the cut-out switch and then trying for current. The car can in any event be run on the remaining motor. On returning to the shop the open can be determinetl definitely by the use of the lamp bank. But should no cm-rent flow when the l)reaker is flashed on the 6th point it is reasonable to presume that the motors are O. K. and that the open is elsewhere. The ground for such a supposition is that as there is a path through each motor normally, there would necessarily be an open in each one to stop the current. It is hardly probable that such a coincidence would occur. After failure to find fault with the motors, doubt as to the resist- ance may be removed. The controller should be placed on progres- sive series-resistance points and the breaker flashed on each one. If current is obtained on any point, the open is in the resistance or the resistance lead just behind the one being used. Special care should be used to flash the breaker quickly for otherwise the fuse may be blown. The tests indicated are sufficient for the motors, controllers and resistance wiring. If no current is obtained on either of them, the trouble is evidently caused by a bad rail contact, ground wire oflF if both motors are grounded through the same wire, an open in the blow-out coil, at the lightning arrester, circuit breaker or on top of the car. None of .the tests applied locate the open definitely, but this can easily be done in the shop or wherever a lamp bank is at hand. Con- nect one terminal of the lamp bank to the trolley just behind the 130 ELECTRIC RAILWAYS circuit breaker and the controller on the 1st point series, then with the other terminal bej^in at <:;r()un(l and trace backwards up the circuit luitil the lamps fail to light. The path in a K type of controller is readily traced with the help of Fig. 22. SHORT=CIRCUIT TESTS. The location of short-circuits is much more tedious. The blowing of the fuse or opening of the breaker will locate them as shown below. The separate tests can then be followed until loca- tion is definite. These tests it must be kept in mind are m5re especially adapted to cases on the road or where no facilities for testing are at hand. Rather than blow fuses as frequently as indicated it would in most cases be better to place a lamp bank across the open circuit breaker and note the flow of the current by the lights. Fuse Blows : I. When overiiead is thrown on may be due to: 1. ( J rounded controller blow-out coil. 2. Grounded trolley wire or cable.. 8. (1 rounded lightning arrester. II. On first point: 1. Ci rounded resistance near R 1. 2. Grounded controller cylinder. 3. Bridging between the insulated sections of cylinder. III. Near last point series: 1. Grounded resistance near R 3, R 4 and R 5. 2. No. 1 motor groimded. IV. Near last point multiple: 1. No. 2 motor grounded. 2. Bridging between lower sections of cylinder, 3. Armature defective. CASE I. Fuse Blows when oyerhead is thrown on: 1. (jrounded controller blow-out coil. 2. Grounded trolley wire or cable. 3. (irounded lightning arrester. Tlie blowing of the fu.se immediately on closing the overhead switch or circuit breaker, when the controller is on tlic off position, ELECTRIC RAILWAYS 131 indicates that the fault exists somewhere between the overhead and the upper or trolley finger of the controller. Should the defect occur during a thunderstorm, it may be pre- sumed at once that lightning has grounded the blow-out coil of the controller. CASE II. Fuse Blows on first point: 1. Grounded resistance near R 1. 2. Grounded controller cylinder. 3. Bridging between sections of cylinder. When the controller is on the first point all of the wiring of the system with the exception of the ground wire for No. 1 motor is con- nected with trolley. But a defect in the wiring beyond the resistance will not show itself on the first point by an abnormal rush of current Fig. 101. Fig. 102. because the resistance of the rheostats is sufficient to prevent any excessive flow of current. The resistance and leads and the contj-oller cylinder are the only parts to be tested when the fuse blows on the 1st point. CASE III. Fuse Blows on 3rd or 4th point: 1. Groimded resistance near II 4 or 11 5. 2. No 1 motor grounded. With either of the above defects the car will most probably refuse to move as the current is led to ground before passing through the motors. 132 ELECTKIC KAIL WAYS Nor c- Dotted lines ~sho>v •Sky/ighfs. Atl partitions are of ^itrifiea tile. Fig. ion. Plan of Car Shop. ELECTRIC RAILWAYS 133 No. 1 motor may be tested by cutting it out of service by means of its cut-out switch. If this removes the ground, the motor is at fault. CASE IV. Fuse Blows near last point multiple: 1. No. 2 motor grounded. 2. Either armature short-circuited. Tlie fact that the fuse did not blow on the series positions excludes the resistances and No. 1 motor from investigations for grounds. Cut out both motors. If the ground still exists the controller is defective If not, the fault mav be located in either one of the motors by cutting out first one and then the other. ARflATURE TESTS FOR GROUNDS. ^Yith a lamp bank at hand tests for groimded armature can be made as follows: Throw the reverse on center. Attach one terminal of the lamp bank to the trolley. Put the other tenniual on the commutator of the armature to be tested. No current shows the armature O. K. If current flows remove brushes and try agaiu, to be certain that the ground is not iu the leads. FIELD TESTS FOR GROUNDS. Disconnect field leads and put test point of the lamp bank on one side of the terminals. No current indicates that the fields are O. K. REVERSED FIELDS. In placing new fields in the shell it often happens that one or more are wrongly connected. Reversed fields make themselves known by excessive sparking at the brushes in each case. In Fig. 101 all of the fields are connected correctly. The flow of magnetism is in one pole and out of the adjacent one. Some of the magnetism leaks out of the shell and affects a compass held near the outside. The direction taken by the compass needle in the dif- ferent positions is shown The needle should point in opposite directions over adjacent coils and should lie parallel to the shell in positions half way between two coils. Figure 102 shows the flow of magnetism when one field is re- versed. In such a case the compass will take the position shown. The fiekl marked "X" is the one reversed. With one reversed field a machine will usually operate, as the 134 ELECTRIC RAILWAYS magnetisiii in three of the poles is in the normal (hrection. Bnt an excessive flow of current that has no eftect in turning the armature will take place on that side of the armature next to the reversed field. CAR REPAIR SHOPS. Every electric railway system has a repair shop in which the cars are overhauled. Hardly two shops are built alike. In those shops where only a few cars are cared for, the work is sometimes all done in one room. The shop plan shown in Fig. 103 was presented to the American Railwav Mechanical and Electrical Association hv W. D. Wright. It contains the idea upon which the larger shops are now being constructed, having a transfer table between the separate departments on either side. In the general design of shops the blacksmith shop, machine shop and truck shop or ecjuipping shop should be close together as a great deal of heavy material is carried between these departments. The paint shop should be separated as much as possible from the other departments in order that flying dust and dirt be avoided. The wood shop may occupy a position at a considerable distance from the other departments as no heavy material is carried from this shop to them. The tracks of the motor and truck repair shop are usually pro- vided with pits so that trucks and electrical ecjuipment may l>e re- ])aired and inspectetl from below. The tracks in shops are usually about 15 or 16 feet between centers. This gives a clearance of about 6 or 8 feet between cars when adjacent tracks are occupied. A large portion of the work done in the average shop consists of the repairing of trucks and the motors mounted on them. With the smaller car, especially those with single trucks, much of this work is done from the pit below while the trucks are in position under the cars. In this case the armatures are either removed by letting them down with the lower half of the motor shell by means of a pit jack, or the lower half of the armature shell is swung down by the use of a chain and block placed in the car and the armature rolled out on a board. The trucks of double truck cars are usually taken out from under the car body when repairs are to be made. In this case the motor leads, the sand box connections and the brake rigging are disconnected and the car bodv either raised or the tiiicks lowered from it. Several ELECTRIC RAILWAYS 135 metliods of raising the car body are in use. Where no special ap- paratus is at hand, this is done by means of jacks, hych-aulic or me- chanical, placed untler the side sills of the car near the end to be raised. Sometimes an overhead crane is employed to lift the car body. A special apparatus to raise the body is employed by the St. Louis Transit Company. This consists of four screw jacks located below the floor of the shop. An I-beam. extends over the tops of the two located on the same side of the car. The jacks are motor driven by means of one sprocket chain so that they rise at the same speed. When a car is to be raised it is run on the track between the jacVs, bars are placed under the car resting across the I-beams and the jacks raise the car off the trucks. The trucks are then rolled out from under the car and the repairs made. Sometimes, as has been stated, the trucks are dropped from the car body. In this case the car is so placed that the truck rests on an elevator or section of track that drops to the floor below. After the car is blocked up the trucks are-dropped and the repairs made. This method is also used in changing wheels in small shops. The old pair of wheels is dropped by a hand-operated drop section of track. A new pair is then elevated into position. This saves jacking up one end of the car. THE SINQLE=PHASE ELECTRIC RAILWAY. In 110 other lino of electrical activity have developments durinfif the last few years been so rapid as in that of electric railway work, and from all indications the limit has not yet been reached. Until recent years all electric traction has been dependent upon direct current as a motive power. This is due principally to the fact that the series direct-current motor is admirably adapted for such work, and no alternating-current motor had been developed which could be substituted for it. One of the great advantages possessed by the direct-current series motor is its large starting torque, which may be several times greater than that required to propel a car at full speed. This type of motor is also essentially a variable speed machine, and lends itself very well to wide varia- tions in speed control; consequently, for many years, in this coun- try at least, all advance was made along direct-current lines. The trolley voltage used at first was from 450 to 500 volts, this being supplied directly to the cars by means of a trolley wire, the rails being used for the return circuit. It is evident from the outset that the comparatively low voltage, necessitating as it did a correspondingly large current for a given amount of power, would place a definite limitation on the use of such a system for anything other than purely local distribution. To overcome this difficulty as far as possible, the trolley voltage was gradually raised to 600 or 650. This of course decreased the required current, thus increas- ing the scope of the system accordingly. The limit of increase of direct-current voltage on the trolley was reached at about this point, and the fact was recognized that some means must be devised for using a still higher voltage, since there are difficulties to increas- ing the trolley voltage beyond 600 or 700, due to flashing of the motors, which seems to increase directly with the voltage. It may be mentioned in passing that one prominent electric traction expert has stated that a direct-current trolley voltage of 1500 can be used, but it remains to be proven whether or not he is correct. 138 THE SINGLE-PHASE ELE(TRI(^ RAILWAY A v(>ry satisfactory solution of the prol)lcm for large city street railway systems and long interurhan roads, consists in the use of a combination alternating-current direct-current system in which three-phase high tension alternating current is generated and distril)- uted on high tension lines to substations along the road. It is here stepped o o Ml) c ^ >< < H O PC _ 5 3 ^ ^ to d O -t^ o •? 2 < £q ■? Fo ^ at o ^ o *- 52 Z IP 13 CO tr. a >SVTY of ^^**MmHor^ THE SIXGI.E-PIIASE ELECTRIC RAILWAY 18'.) it is impossible to predict at the present time just wliat its limitations may or may not prove to be. This has been made possible by the development of a practical commercial sinujle-phase motor, which {)ermits of the use of alternating current on the trolley wire with all its advantages, and yet sacrifices few, if any, of tiie advantages of the direct-current series motor on the car. This motor, which is the latest and most important develop- ment in the electric railway field, is of the series commutator type, Compensating Alternating-Current Railway Motor. and does not ditter in principle from its direct-current contemporary. It is called the commutator type single-phase motor, and is the one type of alternating-current motor which has the same desirable characteristics for railway work as the direct-current series motor. At first thought it may seem strange that a motor built fun- damentally on the same lines as a direct-current machine would operate on an alternating current, as it might appear that the motor would tend to turn first in one direction and then in the opposite direction with no resultant motion. This, however, is not the case, because the direction of rotation of a motor depends upon the rela- tive direction of its field and armature currents. If now the field were maintained in a constant direction and the armature supplied with alternating current, then the tendency would be to rotate first in one direction and then in the other, it is true, but as a matter of fact the alternating current is supplied to the field in .series with the armature, so that when the direction of current in the armature J-iO TIIK S1.\(;LH-PIIASE electric ILMLWAV chano^os it also reverses in the Held. Tlic result i^ tliat llic relative (lireetioii of current in tlu> field and armature is constant and the motor has, therefore, a tendency to turn eontinuouslv in ()n(^ direc- tion as lon^ as the alternatin<:;-current power is suj^plied. This bein^" (rue, the (piestion may arise as to why the sinueral Electric apparatus, and has maintained a regular sched- ule over a distance of more than 10 miles since ]March, 1005. The j)lans are now being laid for a single- phase road, which will run south from Spokane, Washington, a dis- tance of 150 miles. The current on the transmission line is 45,000 Armature Quill. 140 THE SIXGLE-PIIASE ELECTRIC RAILWAY volts, which is stej)po(l down to (i.fiOO on thr trolU-y. The car will l>c cajKihlc ;)f oj)cratint;- on cuircnt from a (>,(K)()-V()lt alternatinji;, a 700-volt alternating, or a oT.Vvolt direct-current supply. Perhaps the most important nunc which has been made in the direction of .sinf^le-phase traction thus far is the decision of the New York, New Haven, and Hartford road to estaUlish a long-distance passenger traffic on the single-phase system. According to the latest plans this road will operate hetween the (Irand Central Depot and Woodlawn, X. W, over the terminal tracks of the New York Central road, on direct current taken from the trolley. From ^^'ood- A Pair of l)ri\ti> with Sinjjle-Phuse Molur Mounted iii)oii (^uill. lawn, X. Y., to Stamford, Conn., the road will he operated on the single-phase system. The ecjuipment is being sujjplied by the Westinghouse Co. The current is generated by revolving-field type tiu'bine-driven alter- nators. The armatures are designed for either three-pha.se or single- phase connection. The current is generated at 25 cycles and 11,000 volts, being delivered directly to the trolley, and thence to the cars, without the intervention of anv transformers. The double catenarv suspension from messenger wires is used to support the trolley. The locomotives are each ecjuipped with foin- 200-H. P. gearless motors, designed to operate on 2oo-volt alternating current and 275- to 300-volt tlirect current. THE SINGLE-PHASE ELECTRIC KAH.WAY 147 'Vhv anuaturc is not inountcHl on tin- .shaft direct, l)Ut is built ii})()ii a ({uill tlir()uL' INDEX PufTO Potter third-rail shoo \i\ Power cost of 119 economy in 1 1 ,S taken by cars 115 Power house location 101 Power stations, general jilan of 105 Power supply and distribution OS Railway motors bearings 13 brushes 10 characterisics of 3 gearing of ." 12 lubrication of 13 Rate of retardation in l)raking 00 Resistance of t rack 91 Resistances 38 Return feeders 92 Reversal of motor 20 Reversed fields 1 33 Rheostat control 17 Road tests of electric cars 117 Sectional insulators 70 Series-parallel control 17 Shanghai T-rail 84 Short-circuit tests 1 30 Single trucks 48 Single-phase electric railway 130 Single-phase motors 114,139 Sleet on trolleys and third rails 40 Sliding and spinning wheels 119 Span wires 74 Sparking at the commutator 1 27 Sprague mutliple-unit system of control 29 Steel car framing 71 Storage air V)rakes 58 Storage batteries in stations 113 Street railway motors, general data on Supplementary return feeders 92 Swing bolster trucks 49 Switchboards 1 00 alternating-current 110 Switches, third rail 79 Swivel trucks 48 T-rail • 84 Thermit welding 88 Third rail 79 advantages in operation 80 INDEX i:,3 . - -■ i__ Page Third rail "comluptivity of SO cost of SO higliway crossings SO insulators for 79 location 79 switches 79 Tliroc-pliasc motors 11;^ Track brakes.. ()3 Track construction S3 Track resistance 91 Track sandcrs. . 05 Track support S5 Transmission systems, efficiency of 101 Trilby groove rail S4 Trolley ba.se 44 Trolley harp 45 Trolley poles 44 Trolley wheeli^ 44 'I I'olley wire ' 73 Trolley-wire clamps and cars 73 Trucks • ' 10 maximum fraction 51 single ''^ swing bolster.. 49 swivel 4S Type L controllers, wiring of 24 ANNOUNCEMENT OF COMING BOG ICS PRAGTICAL^^ SCIENTIFIC CARPENTRY. By G. Townsend. 150 pp., 224 illus. A working; iiiatiiial (or Carpenters and Wood- workers in general. Not a theoretical treatise, but a pra(tii;il rioriin,!; xiiidr. I'rice,$1.00 GAS ENGINES AND PRODUCERS. By Marks anrt Wvcr. l.SO pp., 90 ilhis. Latest information in this rapidly developing: field. For Engineers, Machinists, Automobilists. I'rice $1.00 MASONRY CONSTRUCTION. By Phillips and Byrne. 1-10 pp., 44 illus. Latest and best American methods. I'rice $ 1 .00 WATER SUPPLY. By F. E. Turneaure. 150 pp., 40 illus. 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