US1794543A - Method and apparatus for train control - Google Patents

Description

March 3, 1931. N. D. PRESTON 1,794,543

METHOD AND APPARATUS FOR TRAIN CONTROL Filed Feb. 15, 1922 Patented Mar. 3, 1831.

ere? mate NEIL PREQEON, OF ROCHESTER, NEW YORK, ASSIGNOR '10 GENERAL RAILWAY SIGNAL COMPANY, OF GATES,-NEW YORK, A CORPORATION 'OF NEW YORK METHOD ANDAPPARATUS FORTRAIN CONTROL Application filed February'15, 1922. Serial Ho. 536,750.

This invention relates to automatic train control systems for railways, and more particularly to a method and apparatus for transmitting or communicating influences from a trackway to a moving'vehicle or train, dependent upon the presence and location of another train ahead, and adaptable for the control of cab signals, brake control mechanism, or other safety devices.

Briefly and generally stated, the elemental objects of this inventionare to provide a method, and a specific apparatus for practicing such method, by means of which appropriate controlling influences may be com- 1 municated to moving trains dependent upon the presence and location of another train im-- mediately ahead, which will act inductively through an intervening air gap without physical contact, will maintain a continuous communication, so that a change in trafiic'conditions ahead will be instantly manifested devices'and circuits beingillustrated more with a View of making the nature. of theinvention readily appreciable, than withthe purpose of illustrating the exact construction.

and arrangement of parts preferably employed in practice. v v V I Referring to the accompanying drawing,

byfinsulated joints 2 into ,tracl: sections'or blocks in the usual way,one block B with the ends of the two adjacent blocks A and 0 being shown. These blocks are provided with direct current polarized track circuits in c n and advantages of the invention will be in the track rails 1 of the railroad are divided formity. with well-known practice. The

parts and circuits associated with the several blocks are the same, and for convenience Wlll be given the same reference characters with distinctive exponent-s. At the entrance end of each block, traffic being from left to right as indicated by the arrow, is a track relay 3 of theusual neutral-polar type,'wh1ch 1s provided with pole changing contacts controlling the connection between a track battery 4 and the track rails at the exit end of the next pre- The cab signal or cedingblock in the rear. train control system governed by the influence coimniuncating means constituting this invention may be used with or without the usual traclrway ii-iedsignals, and such signals S have been shown conventionally, without attempting to illustrate their, control circuits, which maybe of any one of the well-known types.

it locomotive, cr'other railway vehicle, is

illustrated conventionally as a pair of wheels and anaxle. In accordance with this invention, t ere are carried by this vehicle, supported, housed, and protected in any suitable manner, .detectingcoils 55 which are carried in front of the first pair oi wheels and axle of the vehicle, directly over the track rails 1. These coils 5 may be of any suitable shape, and are mountedon a suitable frame supported by anti-friction bearings,

so as to be rotatable on an axis extending along the rails. In other words, these coils are arranged so that, when rotated, they will cut the magnetic lines of force or flux which i encircle or surround the track while the direct current from the track battery 4: is flowing therein. vThe detecting coils 55 are provided with commutators and brushes, desig nated 6 630i suit-able construction,- corresponding to that commonly employed in direct current generators, to convert the alter natin'g E. M. F. generated in said coils into a uni-directional voltage. These receiving coils 5.5 are continuously rotated by some suitable instrumentality. In the specific arrangement shown, small direct current motors of the shunt type 7'?, connected in multiple, and suppliedwith current from a suitable battery 8 or other source, are directly coupled si nifies clear or proceed, the lumpy (yellow) s1 to the frames or supports for the coils 55 While under favorable conditions the generated current obtainable in the receiving coils 55 may be employed to actuate an electro-responsive device directly, on-account of practical limitations, it is preferred to amplify the voltage manifestations in said coils, so as to obtain an amount and form oi ener 'y adaptable for the operation of ordinary relays of the tractive type orequivalcnt types. For thispurpose a thermionic amplifier or relay of the well-known vacuum tube type is preferably employed, although any suitable electro-responsive device with amplifying characteristics may be employed. The thermionic amplifiershown, commonly termed an audion, comprises a filament F, a grid G, and a plate P. Since the characteristics and mode of operation of these audions are well understood in the art, it is -deemed suliicient to point out the way in which such characteristics are utilized in connection with this particular invention.

Referring to the specific arrangement shown, two audions 9 and it) are used. The filament F or" each audion is heated by a battery'll in the usual way. In the plate circuit of'the audion 9, energized by battery 12,,is connected a relayE which may be of the tractive, d mamometer, or other type, best adapted for the particular worlring conditions under which the invention is practiced.

,Itis contemplated that the contacts or circuit controlling elements or" this relay will be biased or counterweighted so as to change as the energizing current of the relay is cut oil, or decreased below the hold up value. Tnthe plate circuit of the audion l0, energized by a battery 13, is a similar relay The contacts for the relays R and R are shown conventionally; and while the selective operation of these contacts may be employed to control cab signals or any suitable form or" train control mechanism, or both in a simplified ar rangement as illustrated, three lamps, 7', y and g and a device K, are governed in con formity with the energization control of said relays R and R The lamp g may be green orany other suitable color, and when lighted signifies caution, and the lamp 1 (red fies stop or danger.

The device K may talre various forms, and since its specific construction or mode of operation forms no part of the present invention, it is unnecessary to discuss its operating characteristics in detail, it being noted that, according to the specific arrangement of circuits shown, this device K is one which is maintained inactive while energized, and is set into operation or rendered active when The device K, when set into Clo-energized. operation, may cause an immediatebralre application in any suitable manner, or bralre application in case the engineer fails totalre appropriate action, or a brake application dependent upon the vehioles speed being in eXcess of some fixed speed limit, or in excess of a speed limit changeable in accordance with the progress of the vehicle. It may be added that, on account ofthe continuous control characteristics of the influence communieating means constituting this invention, a cyclic train speed control of the type shown and. described, for example, in thepatent to Simmen, 1,150,309, August 17, 1915, may be employed to advantage,

The control circuits for the lamps 1", 3 and g, and the device K, may be readily tracedon the drawing. VVith the relay R up and the relay R down, the lamp 9 is lighted and the device K energized, corresponding to clear traffic conditions. Nith the relay R down and the relay R up, the lamp y is lighted, and

the device K deenergized, corresponding to caution conditions. With both the relays R and R down, the lamp 1' is lighted, correspending to danger or stop conditions, the device K being still deenergized.

The receiving coils 5-5 are connected in series, through their commutators 6-45, and are connected in the grid circuits of the two audions 9 andll) ina reverse manner. The circuit connecting the receiving coils 5 and 5 in series and maintaining a potential on the grid G of the audion 9 with respect to its filament F may be traced as follows :-commencing at the grid G, wires 1% and 15, upper brush of commutator 6 through the coil 5?;

lower brush of said commutator, wire 16, upper brush of commutator tl, through coil 5, lower brush, of said commutator and wires 17 and 18 to the filament F. The coils 55 are so wound, and connected that the voltage induced therein, when current flows in opposite directions in the respective track rails, will be cumulative or additive. To illustrate, assuming a certain direction of current flow in the track rails 1 and a certain direction of rotation of the coils 5 and 5 these coils are so wound and connected to the commutators 6 andli thatthe upper brush, for example, of the commutator 6 will be positive, as indicated, whereas the lower brush of the commutator 6 willbe negative; WVithout tracing the circuits,iit can be easily seen from the drawing thatthe upper brush of the comnutator 6 assumed for the purposes of eX- planation tojbe positive under clear traliic conditions illustrated in the drawing, is conected' to the grid G of he audion 9, while the filament l? of this same audion is connected to the lower brush of the commutator 6, thereby making the potential of this grid positive with respect to the filament. Similarly. the lower or negative brush of the commutator 6 is connected to the grid G of the FAD tivewith respect to its filament. Onaccount of thereverse connections of the grids of the audions 9 and 10, with any given direction of current in the track rails, the potential onzthe grid G of one audion is positive, for exam ple, and that on the other audion negative. The various circuits, voltages, and characteristics of the audions 9 and 10 are selected or proportioned such thatIa positive potential on the grid of either audion-S) or 10, will allow sufiicient current to flowin the plate circuit ofthat audion to pick up and hold up thecorresponding relay vR or R whereas with a substantially zero potential on said grid, the

plate current is so reduced as to allow the corresponding relay to drop'away inresponse to its biasing force. On account of the wellknown characteristics of the vacuum tube amplifier or audion, when the grid potential is reversed and becomes negative with respect to its filament, the current is less'than when the grid, is at a zero potential and much less than when at a positive,potential.

From consideration of the polarized track circuits illustrated, it willbe evident that, ,under clear traiiic conditions,'the current in the track rails of each blockwill flow in one direction in one rail,.and in the opposite direction in the other rail, as indicated, for example, by the arrows a.- When there is a train in the block, as the bloclrC, the track relay 3 of that block is caused to drop its armature inthe usual Way, and this reverses the connections of the track battery to the track rails of the block next in the rear, as the block B, so that the currents in track rails of this block in the rear, while still flowing in opposite directions relatively to each other, are in the opposite direction to that under clear traffic conditions. lVith a train in a block, its wheels and axles form a shunt of very low resistance, so that very little, if any,

current will flow through the track rails in front of a vehicle entering tliat'sameblock,

Thus, under clear traiiic-conditions, th-e'voltage induced in the coils 55 is of one.

polarity, causing one relay R to pick up and the other relay R to drop; undercaution traflic conditions,,the polarity ofthe voltage generated in the coils 5- 5 is reversed, re? versing the potentials on grids of the audio'ns 9 and 10 and causing the relay to drop and the relay R to pick up; and under dangerous trafiic conditions practically no vol age is generated in the coils 55 reducing the potential on vthe grids of the audions 9 and 10 to zero, and causing both relaysR and R to drop. In this way, there are received on the car the three indications of clear, caution, and stop; and these indications maybe used in any suitable manner, as indicated above, to control the brakes of the vehicle and regulateits movement arbitrarily,

or dependent upon speed or other condition:

These three indications of clear, caution, and

tions, a change to a more favorable indica- 1 tion taking place automatically and instantly as soon astraiiic conditions ahead cleanup. Itis noted that one audion and relay are sufficient for two indications, and since certain types of speed governed brake control mechanism, require only two indications for their proper control, it isevident that an adequate train control system may be devised in accordance with. the principles of this invention with the use of one relay and one audion alone; I

Itwill beiobse rved thatthis invention provides the reception of the desired controlling influences without the addition of anytrack o, devices or source of energy. The influenceis communicated continuously, and the various circuit connections are such that interruption thereof, depreciation or failure of the car carried batteries, crossings between wires, and other defects likely to occur, will all cause cessation Jotthe communicating influence and produce an effect on the side ofsatety. .Also, such continuous control possesses the desirable chara cteristicof instantly manitesting on a following car at any point in a blockachange intraliic conditions in the next 1 block in advance. F or example,if thetrain is in theblock B, anddanger conditionsin theblock C are indicated by the vdropping of'the track relay 8?,apparatus on the following train will instantly respond as soon as the conditions in blockC change from danger to caution or clear, entirely irrespective of the position of said following train in the block :13. This latter characteristic is obviously of great value in speedIcontrolsystems in which a vrestrictionupon tra n movement is imposed and continued untilan automatic release or restoration is obtained from the trackway; and, the indications of the cab signalidevices, f used, correspond correctly to the 1nd1cations of the traclrway fixed signals.

It will be appreciated that the relatives i zes and proportions of the parts and electrical constants of the various clrcuits are susceptible'of considerable adaptation in practice, in

order to obtain the most favorable results 'undera given set of working conditions; and consequently, no attempt has been made to,

show and describe any specific arrangement.

It should be understood, however, that two in track rails, it being evident that stray currents flowing in opposite directions in the re- 7 spective track rails, and of a suiiicient magninot be improperly affected by any stray tude to cause false operation of the train control equipment, will likewise have a tendency to produce false operation of the'regular track relay. Putting it another way, it may be said that the train control apparatus will currents in the track rails which would not also tend to produce improper track circuit operation, a condition which would have to be in some way remedied.

Since, the length, ballasted conditions, battery voltages, and the like, for different direct current track circuits now in common use on V railroads are somewhat variable, it may be necessary in practicing this invention to modify these factors in some cases in order to obtain satisfactory operation of the train control system. .For example, so-called cut-sectial at the relay end; and similar adaptations made in existing track circuits in a manner ev1dentto those sk1lled in the art, so as to obtain the desired value of current in the track rails in front of a train on a given track circuit at the difierent points in the travel of such train. With proper provision for amplification, however, the current in the track rails may be very small; and except for the danger of possible interference by feeble magnetic fields near the track rails from other sources than the proper current,-no arbitrary amount of current in the track rails isnecessary to prac ice the invention. The detecting or receiving coils 55 are preferably used Without iron cores so as to avoidpos'sible'difiiculty with the effects of residual magnetism, and similarly the instrumentality driving these coils, which has been shown for simplici ty as small direct currentmotors, will like wise be designed or protected in the practical application of the inventionto avoid such interference.

It is pointedout in this connection that a magnetic field through both of the. coils 5-5? in the same direction produces no efiect, since the voltages generated in these coils in such a case will oppose each other. In short, while appropriate design and selection of electrical constants are necessary in practicing thein vent-ion under varying working conditions existing in practice, as a general proposition, the system of communicating influences in the manner characteristic of this invention is adaptable to direct current track circuits as now commonly used, thereby enabling the application of the train control system to railroads without material change in their trackway equipment, providing additional sources of current, or adding to the trackway anythingthat may interfere with their rolling stock clearances.

The specific construction and arrangement of parts and circuits'shown and described are obviously susceptible of much adaptation and modification without altering the nature and characteristic of the invention; and I desire to have it understood that this drawing and specification are merely an illustrative disclosure of one particular'type of means for pracicing the method and carrying out the functions'of the apparatus constituting my invention;

What I claim is p 1; The method of communicating influences to moving trains "in conformity with trafficv conditions, which consists in supplying to the traclr'rails a direct current of one or the other polarity, converting the field of flux around the track rails created thereby into a current of like polarity on a moving canand amplifying such current on the car and utilizing ity to govern safety mechanism in confornity with the existing polarity of current in the track rails. Y

2. The method of communicating influences to moving trains for train control purposes, which consists in supplying to the track rails normally a direct current of one polarity, reversing the polarity of such current for a limited distance in the rear of a train, detecting such current without physical contact, and governing safety mechanism on a following trainin accordance with such change of polarity.

3. The method of communicating influences to moving trains for train control purposes, which consists in continuously supplying acontrol current to a moving car by the presence of a continuous direct current in a conductor disposed along the path of movement of said our, amplifying such current and utilizing it for governing cab signals or train control mechanism.

a. The method of communicating influences to moving trains for train control pur poses, which consists in supplying a control current continuously to a moving car without physical contact by a continuous direct current in a conductor disposed alcng the path of movement of the car, modifying the direct current in the conductor at times to correspond with the varying traffic conditions, and'utilizing variations in the current on the car for cab signals or-train control purposes;

n or .5. The method of communicating influences ton'ioving trains for train control purposes, which consists in changing the existence and the direction of how of direct current in a conductor disposed along the'p'ath of movemen t of a vehicle, producing'without physical contact with said conductor a current in a circuit wholly on the car which depends upon and varies with the presence and also polarity of said direct current in said conductor, and utilizing such flow of current in said car carried ci"cuit for train control purposes. a V 1 6. A method of providing the control influences suitable for cab signals or train control purposes, which consists in dividing the track rails into insulated track sections, supplying direct current to the rails of each track section the polarity of WhlCll'lS dependent upon the presence or absence of a train in the next track section in advance, and producing in a circuitwholly ona following car a current corresponding to and dependent upon the presence of such current in the track rails, and utilizing the currentin the car carried circuit for train control purposes.

7. A method of providingthe control influences suitable for cab signals or train con trol purposes, which consists in dividing the track rails into insulated track sections, supplying direct current to the railsof'each track section of a polarity dependent upon the presence or absence of another train in the next track section in advance, converting the field of flux around the track rails into a current on a following vehicle, amplifying said current on the following vehicle, and utilizing the amplified current to govern cab signals or train control devices.

8. The method of communicating train movement influences trom'the trackway to moving vehicles for cab signals or train control purposes, which consists in forming a series of normally closed circuits, partly on the track and partly on the moving car with an interposed air'g'ap, and supplying said circuits with direct current and providing therein devices for detecting and amplifying a constant field of magnetic flux. V

9.- In a system of cab signals or train control'tor railroads, the combination withpolarized direct current track circuits, of means on the car for producing without physical contact with the track rails a derived voltage at all times corresponding to the existence and polarity of the current in said track circuits.

10. In a system of cab signals or train control for railroads, the combination with a track divided into track sections each having a-polarize'd direct current track: circuit, ot

automatic means on the car for detecting and amplifying the eltect of the current ot said track circuits flowing 1n the track rails.

11. In a system of cab slgnals or train control for railroads, the combination with a conductor along the track inwhich continuousdirect current is'flowing,means 0n the moving car detecting the field of fiux'created by such current, a device to be governed, and

amplifying means controlled by the detecting ii cal contact.

13. In a system of cab signals or train control tor railroads, the combination with a track rail carrying continuous direct current or" one polarity, of car-carried means for detecting. the flow of said current without physical contact, a device to be governed, and amplifying means responsive to the detecting means for governing said device.

14;. in a system of cab signals or train control .tor railroads, thecombination with a track rail carrying direct current, car-carried means comprising detecting and ampli tying devices responsive to the presence and polarity of said current. I p

15. In a system of cab signals or train c011- trol tor railroads, the combination with a' track rail and a source of direct current, track circuit control means controlling the connections between said source and the track rail, and means for amplifying and detecting the flow of current in said rail without trollable device on a car tending to assume its act ve condition, and means responsive to the presence and polarity of the current in the track rails without physical. contact for governing said device said'means convertin' 'b electro-ma netic induction the m agnetic field of said current in the track rails into an electrical difference of potent ial. a a

17. A train control system comprising, a pair of track rails and a source of direct current connected thereto, and voltage producing meansion a car disposed in front of first pair of wheels and axles, and responsive to the flow of said current in said track rails. 18. Car, apparatus for train control sys tems comprising, a constantly rotating coil carried relatively close to and above the track rail on which the car runs to cutthe magnetic flux produced by current How in said rail.

19. Automatic means for detecting the presence of direct current in the track rails on which vehicles travel comprising, means carried by the car in front of its first air of wheels and axle for producing a di erence or potential corresponding to the magnetic field around said track rails which is pro duced by the flow of direct current therein,

and biased electro-responsive means and a car-carried source of current controlled by said diiierence of potential.

20. Influence communicat ng means of the character described comprising, in combination with a conductor on the trackway carrying current,of car-carried apparatus comprising, coil'in the field produced by the current flow in said conductor, means for ro-- tatingsaid coil, a commutator, a relay, and amplifying means connecting said coil and relay.

r 21. In a train control system, the combination with a conductor disposed along the path of travel of the vehicle a d carrying direct current, and means on a vehicl for detecting without physical contact the existence of such current in the track rails comprising, a

generating coil, an amplifying means and an electrO-responsive device.

'22. In a train control system. the combination with the rails of track sections in which direct current flows in opposite directions under clear and caution trafiic conditions, means on a car for changing the field of flux of such current into a potential, safety mechanism on the car, and amplifying means responsive to said potential for governing said safety mechanism.

23. A system of continuous inductive control for railway vehicles'co i prising, in combination with polarized direct current track circuits, detecting and amplifying means on combination With detecting and amplifying means on a car responsive to constant unidirectional magnetic field, of track circuit control m ans for supplying such field to the car-carried means at all points in the travel ot the carf p v 25. A system of inductive continuous control for cab signal and train control systems characterized by the detection and amplification of the effect of continuous direct current in a conductor along tle path of movement of the vehicle without physical contact.

26. In a cab signalor train control system for railroads, in combination with a sectionalized railroad track, a battery for each section, means acting when a given section is not occupied to connect the battery of the section next in the rear across the track rails at the exit end thereof, means carried on the car relatively close to and over each track rail in front ofthe first pair of wheels and axles of the car torproducing a uni-directionalvoltage of a definite polarity which is derived from the current flowin said tracl: rails, and means on the car including a car-carried source or" energy and governed by said voltage.

27. In a train control system, a track divided into sections, trafiic controlled means automatically applying a uni-directional difterence ofpotential across the track rails of each section at its exit end to produce a direct current, car-carried electroresponsive means and a source of energy on the car connected thereto, and means carried bythe car over a track rail and acting automatically to change the flow of current from said source to the electro-responsive means in correspondence with the direction or" said direct current in the track rails without circuit interruptions' i V 28. In a train control system, the combination with a line of track rails in which direct current flows in opposite directions, and means carried on the car in front of the operati or a with the magnetic field produced by the flow of said current in the track rails for producing inductively a difi erence of potential on the car having a predetermined polarity corresponding to the direction of flow of said current in said track rails.

29. In an automatic traincontrol system for railroads having track sections divided into blocks each having a track battery con nected across the track rails at one end, car apparatus comprising a relay, a source of current for energizing said relay, a vacuum tube amplifier having its plate circuit connected to said relay, and means disposed in inductive relation to said track rails in front of the first pair of wheels and axle of the car and responsive to the constant uni-directional magnetic field produced by the current flow in said tract: rails from said buttery for imposing a corresponding potential on the grid of said amplifier.

30. In a system of cab signals or train control for railroads, the combination with an insulated track section, a source of direct current, and automatic means for connecting said source across the track rails at one end of said section thereby producing a flow of constant uni-directional current in the track rails; of car-carried means for produci' 31. In a system of the character described,v

the combination wi -h the track rails of a track section in which current of a predetermined polarity flows in opposite directions, of a car-carried element rotating in the magnetic field of the current in said track rails and generating a voltage of cor-' responding polarity.

v32. In a system of the character described, an insulated track section, a source of current connected across the track rails of said section at one end thereof, and car-carried conductors maintained in constant motion on the car in the magnetic field produced around the track rails by the flow of said current therein, said conductors generating a voltage derived solely from such current flow. I

- 83. In a cab signal or train control system for railroads having tracks divided into track sections, each section having continuous direct current flowing in opposite directions in its track rails under certain traiiic conditions, car-carried means having an inherent tendency to assume its active controlling condition and automatically maintained inactive by the 'efiect of voltage in a carcarried circuit derived from the flow of said direct current in the track rails without physical contact with said track rails.

.34. In a system of the character described, the combination with a track section having direct current flowing in opposite directions in its track rails, car-carried apparatus comprising a plurality of circuits to be controlled,

electro-resp onsive means having a tendency to open all of said circuits and operable by unidirectional voltages of different polarities. to maintain certain of said circuits closed in conformity with the polarity of said voltages, and means for producing on the car without electrical connection to the track rails unidirectional voltages which are derived from the flow of said direct current in the track rails and have related polarity.

35. In a train control system, the combination with a track section having current fiowing in opposite directions in its track rails under certain traffic conditions, car-carried apparatus comprising a relay, an audion controlling said relay, and means for appl ing to the input circuit of said audion a unidirectional voltagc derived solely from the magnetic field of said current flow in the track rails.

36. In a train control system for railroads having track sections in which direct current of different polarities flows in opposite direc-- tions in the track rails, car-carried apparatus comprising two three-element vacuum tube amplifiers, and means varying the grid potentials of said amplifiers in the opposite sense to correspond with the polarity of the direct current flowing in the track rails.

37. In a system of the character described, the combination with a track rail in which current flows, of a coil, and a commutator on a car constantly rotated in the field produced by such current flow.

38. Car apparatus for train control systems comprising, a coil in front of the first pair of wheels and axle of the car and'disposed over Way vehicle at all points in its travel any one of a plurality of control influences suitable for cab signals or train control purposes, which consists in applying a uni-directional electro-motive-force across the track rails at the exit end of an isolated track section so as to cause a flow of direct current in opposite directions in said track rails, varying the polarity of said electro-motive-force for each track section in correspondence with the presence or absence of other trains ahead, and producing on a vehicle at all points in its travel in each traclr section and without electrical contact with the track rails a voltage corresponding to and derived from the flow of said direct current in the track rails of that section.

40. Ina train control system, the combination of a railway track, a vehicle thereon, said track divided into blocks, means controlled by trafiic conditions for energizing a rail of said blocks with continuous direct current,

means on said vehicle responsive to, the current in said rail and amplifying the effect thereof.

41; In a train control system, the combination of a railway track, a Vehicle thereon, means for energizing a rail of said track with direct current, a device on said vehicle responsive, to the current in said rail and controlling a circuit, means for amplifying the current in said circuit and means for controlcurrent delivered by said coil.

48; In combination, a railway train, generating means located on said train and comprising a rotating armature, means located in the trackway. for continuously supplying magnetic flux tosaid generating means when traflic conditions are safe but not when traffic conditions are dangerous, means located on the train for driving said armature, and

train governing means controlled by current suppliedhysaid generating means.

44. In combination, a railway train, gen eratingmeans on said train having an armature, means located in the trackway for supplying said generating means with magnetic ling the polarity of the current in said cirflux of one relative polarity'o"; the other in accordance with trafiic condiaions, means on the train for driving said armature, and train governing apparatus responsive to the polarity of the elec'iro-motive force supplied by said generating means.

In testimony whereof 1 hereto my signature.

NEIL DPRESTON.

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