US1843895A - Automatic train control system - Google Patents

Description

Feb. 2, BODDE AUTOMATIC TRAIN CONTROL SYSTEM Filed May 16,1929

ATTORNEY VEN OR M M, BY

E0 skmok 33 nzml Patented Feb. 2, 1932) p Prat oFFmE 'rnnono-nn BODDE, or nocnnsrnn ivnvr Yonir, nssrenon T GENERAL RAILWAY,

' srenenoomrnmr, or ROCHESTER, NEW YORK 'Anirorrnrrc *rnnnsr comm: SYSTEM "Application filed ne ieg 1929. Serial No. 383,531.

This invention relates to automatictrain control systems, and more particularly to train control systems of the, shoe and ramp" type.

In applying automatic train control to existing railway signalling systems, it is desired to communicate automatically, from the trackway to the movin'gvehicle, the conditions oftrafiic existing ahead of such veof the rectifier may be determined on the C213 hicle. dlstant signal indications are used,. or

whether three indication condition type signalsare used,.in which clear, caution, and danger are indicated to the engineer of the train, it is desirable to manifest on the car at least three kinds of traflic conditions, conventionally called clear or proceed, caution and danger or stop traffic conditions. In

order to transmit a plurality of distinctive control influences from a 's1ngle ramp to a moving railway vehicle, it is necessary to make the ramp distinctive under the various conditions of trattic. v

In accordance with the present invention it is proposed'that the presence ofthel ramp itself be manifestedon the-car by lifting. a

shoe located on that car, and to givethe' ramp two other distinctive characteristics by connecting a rectifier between such ramp, and the track rails, so that through the m'edium of contact between a car-carried shoe and the ramp the direction of. valve action More specifically, it is proposed in accordance with the present invention to employ a polyphase induction-type relay on the railway vehicle, having two windings connected in multiple branches and each winding including a rectifier, in series therewith, these rectifiers having their valve action poled oppositely, and having these multiple branches Irrespective of whether home and beenillustrated as a semaphore signal having the usual &5 degree and 90' degree circults,

sounded during each passage of the carcarrled equipment over a clear or proceed ramp, the provision of means to effect a.

I brake application'that may be easily lan- 'nulled-hy-the engineer upon the passage over a caution ramp and the provision of means to cause vthe brakes to be applied, in such a-v manner that they cannot be easily released, upon passage of the vehicle by a stop ramp; 'Gther objects, purposes and characteristic features of the invention will appear in part as the description thereof progresses, andwill in part b'e obvious from the accompanying drawing. i In describing the'invention in detail, reference will be made to the single accompanying drawing in which one embodiment of the present invention has been illustrated. Track way apparatua lteferring particularly to the trackway apparatus, the rails 1 of a double track railway system, in whichtraflic normally moves from left'to' right in the direction of the arrow, is divided by insulating'jointsQ intO blocks of which the block I and the adjacent ends of two other blocks and J only have'been'illustrated. At the entrance to each" block is provided a suitable signal Z, having a distinctive ex ponent, which signal for convenience has which circuits for "the signalsZ and'Z are energized from the batteries 4: and 4: through contacts of the polar track relays T and T There is also provided at each signal location arepeater relay RE, which isenergized only when the corresponding track relay T is energized to its right hand clear position; this repeaterrelay RR through its contacts 6 and 7 pole changes the rectifier 8 in accordance with the 'energization of the repeaterrelay RR, this rectifier 8 being connected between the track rails 1 and the track-ramp TR through the medium of a semaphore contact" 9 and a track relay contact 10. This semaphore contact is operatively connected to the semaphore signal blade by suitable means conventionally shown bythe dotted line' l l. From thisconstruction of the trackway apparatus, it appears that under clear traflic tive polarity from the trackbattery 11 tov the track rails of the block I, and thereby causing the track relay T to assume its left hand energized position effecting de-energization of the repeater relay RR and movement of the signal Z to the caution position, whereby the rectifier 8 will be connected in a circuit to permit the flow of direct current from the ramp TR to the track rails 1..

It is thus seen, that the pole- changer contacts 12 and 12 assume their normal positive polarity position through the medium of an operative connection indicated by dotted lines 13 and 13 when the corresponding signal assumes the clear or caution position, but this pole-changer assumes the negative position when such signal assumes the stop posi tion. Further, it is obvious that with the track relay T deenergized, as is the case when the block I is occupied, the track ramp TR will be disconnected from the track 1 through the medium of the contact 10 of the track relay T, and also under this condition of traffic the semaphore contact 9 will break theramp circuit.

Oar-carried apparat'us.-On the railway vehicle is carried a shoe 20 adapted to contact with a trackway ramp TR, TR etc. during the passage of the car by a signal location. This shoe 20 not only contacts with these ramps TR, but also is raised during such con tact with the track ramps, thereby opening the contacts 21 and 22 and closing. the con-- tacts 23 and 2st. The car-carried equipment also includes a turbo-generator G, adapted to generate direct current, as conventionally illustrated by commutator 25, and to generate alternating current as illustrated by the slip rings 26, which slip rings 26 are connected to a transformer 27. The car-carried apparatus also includes a main relay MB of the polyphase inductive type, and two neutral stick relays CA and CL for manifesting clear and caution traffic conditions, respectively, and further includes a slow-dropping signal relay SR, audible signals BL and WV, and a suitable normally energized brake control device EPV.

Attention is directed to the fact that the windings 30 and 31 of the two-element inductive type relay MR are connected in multiple, that the winding 30 has connected in nected oppositely in these two branch circuits, the purpose for which will be described hereinafter. The car-carried apparatus also includes an annulling push button AN, and a reset push button RS. It is believed that the construction as well as the operating characteristics of the system are most readily explained by considering the operation of the system.

Operation.-Under normal clear traffic conditions of the car-carried apparatus, that is, when the railway vehicle 35 is moving along the railway track between the ramps when such vehicle has just passed a clear ramp, namely, when the railway vehicle is moving in a clear block, the caution relay CA and the clear relay'CL are respectively energized through the following stick circuits:(1) beginning at the plus bus wire 7 36, contacts 21-, wires 37 38, and 39, stick contact 40' ofthe relay CA, wires 41 and 42. lower winding. of. the relay CA, wires 43 and 44, to the minus bus; and (2) beginning at the plus bus, wire 36, contacts 21, Wires 37, 38, 46, and47, stick contact 48 of the clear relay CL, wire 49 and 50, lower winding of the glear relay CL, wire 51, and 44, to the minus With the relays CA and CL both energized the electro-pneumatic brake control device EPV is energized through the following circuit:beginning at the plus bus, wires 52 and 53, contact 5% of the reset push button RS, wires 55 and 56, contacts 22 of the shoe 20, wire 57, contact 58 of the caution relay CA, wire 59, contact 60 of the clear relay CL, wires 61 and 62, normally closed contact 63 of the annulling push button AN, wire 64, windingofthe electropneumatic valve EPV, wire 65 to the negative bus. It is thus seen that the electro-pneumatic valve is maintained energizedunder the conditions stated, thereby holding suitable pneumatic operated brake control apparatus in its inactive condition, said valve if de-energized causing an automatic application of the brakes of the railway vehicle.

Let us now assume that the railway vehicle represented by the wheels and aXle 35 passes a caution ramp. As the shoe 20 engages the track ramp TR- it opens the shoe contacts 21 and 22 and closes the shoe con tacts 23 and 24:. It may be pointed out here, that the contacts 2123, as well as contacts 2224 are preferably makebefore-break contacts,that is, contacts 23 and 2a are closed before contacts 21 and 22 are opened, and vice versa. l/Vith the shoe contacts 22 opened and shoe contacts 2a closed, the electro-pneumatic valve EPV is maintained energized through the following circuit :beginning at the plus bus, wires 52land53, contact 54 of the reset push button BS, wires 55 and 66, shoe contacts 24, wires 67 and 62, dash pot retardedv contacts 63 of the annulling push button AN, wire6 l, winding of. the device EPV, wire 65, to the minus bus. It is thus seen that the brake control device EPV is maintained'energized so longas the shoe 20 is raised irrespective of the energized conditions of the relays CA and CL. Under this 7 condition with the shoe 20 riding on the-ramp TR under caution traffic conditions, pulsating current may'flow from the secondary 1 windingof transformer 27 through' wire 68,

shoeQO, ramp 'TR,-wire 69, back contact 6 of the repeater relay-RR, wire 7 0, contact 10 of the trackrelay T, wire 71, rectifier 8, wire 72, semaphore contact 9., wires 73 and 74, back contact 7 of the relay RR, wire 75, track rails 1', wheels and axle 35, wire 7 6, winding 31,'rec'tifier 33, back to the secondary winding of-transformer 27. It will be noted that the rectifiers 8 and 33 in the circuit just traced have their Valve action poled in the same direction, thus permitting the flow of pulsating current in" the direction in which the circuit was traced. Also, it is understood that thecircuitjust traced is of rather low resistance and of rather high inductance, so

that a-comparatively'large pulsating current will flow, this-pulsating current lagging considerably behind the voltage of the secondary winding by-reason ofthe inductive characteristic-of the circuit just traced. There is, 110wever', another circuit present, while the shoe 20 is on the caution ramp, which other circuit is exactly the same as the one just traced except that it includes the branch of the main relay MR including the winding 30 and the rectifier32-in series, instead of the branch including winding 31 and rectifier 33. This latter'circuit, itwill be noted, has its recti stantially in phase with the voltage oftrans former 27. With a small amountof alternating current of unity power factor flowing in the coil 30 of the main relay and a comparatively large lagging pulsatmg current flowing in the other winding thereof, a torque isproduced in the rotor of the relay MR; this causes the contact 80 to be moved to the left hand position to complete the following pick-up circuit for the caution relay CA, this caution lrelay as well-as the clear relay CL both having assumed their de-energized position in response to lifting of the? 1 shoe 20, because the stick circuits for both of these relays were then opened by opening the shoe contact 21 :beginning at the plus bus, wire 81, shoe contact 23, wire 82, polar contact 80-of the main relay MR, assuming its left hand position, wire, 83,-winding of the caution relay CA, wires 43 and 4:4 to the minus bus. As the shoe 20 moves off the track ramp" TR the stick circuit for: the caution relay CA, and including the normally closed shoe contacts 21, heretofore'tracedis again closed thus maintaining the caution relay CA energized. f

' l/Viththe caution-relay CA energized andthe-clear relay CL ole-energized, theishoe 20 having leftthe track ramp; TR, the electropneumatic valve EPV is lie-energized, be-

cause the contact 60 of the clear relay CL is now in its de-energiz'ed position, thereby; sounding the whistle W, to advise the engineer'that hewill obtaina brake application unless he operates his annulling push button- AN. The circuit for the whistle valve may be traced as follows :beginning at the plus bus, wires 52 and 53, contact 54, wires 55 and 56, contact 22, wire 57 contact 58, wire 59, contact 60 of the clear relay CL in its lower position, wire 84, winding of whistle valve W, wire 85 to the minus bus. f r i Theengineer may nowiby depressing his push button AN pick up-the clearrelay CL and re-energize the brake control device EPV beforethe brakes are actually fully applied, by closing the following circuit :beginning at the-plus bus, wire 36, contacts 21, wires 37,

'38, 46, and 87, contacts 88 of the push button- AN, wires 89, 90 and 50, lower windingof the clear relay'CL, wires 51 and 44, to the negative bus. As soon as the clear relay CL has assumed its energizedposition, its stick circuit heretofore traced. is closed, thusmaintaming th s relayenergized, and 1f theengi neer then moves his annulling push button to itsnormal position before the contact 63 has had an opportunity-to open, this contact. 631' being a time-controlled 1 contact which opens if the annu'lling' push button AN is depressed, for say more than 15 seconds, the device EPV will again be energized through the circuit heretoforetracedf Letus now assume that the railway vehicle in question, equipped with'the-car-carried ap paratus embody ng the present invention, passes a? danger ramp (a ramp entirely dis connected fromthe'track rails) under which condition the caution relay CA and the clear relay'CL' will'again be de-energized for reasonsheretofore given, the device EPV being maint'ained'energized so long as the shoe 20 is I lifted. Since, under this condition, the main relay MR'will' not be energized by current of 11;

any kind, because the circuit including the rainp and main relay MR isno-w open at the contact. TOOf the track relay T, neither the relay CA nor the relay CL will be energized.

Asthe shoe 20leaves the ramp during passage of. that vehicle by such ramp the temporary circuit including shoe contacts 24 for the device EPV is broken, and the device EPV will assume its tie-energized position and effeet a brake application. alert and decides. it to be safe to allow the train to again proceed before comingto a full If the engineer is stop, he maydepress the reset push button RS not conveniently accessible, but accessible to the engineer only after a certain amount of annoyance and inconvenience.

Such depression of the reset push button RS effects shunting of the stick contact 40 of caution relay. CA by the contact 92 of the reset push button and also the shunting of the stick contact 48 of the clear relay CL by closure of the contact 93 of the reset push button-BS, so that the caution relay CA and the clear relay CL will assume their energized position, and thereafter remain energized through the stick circuits heretofore traced. If the engineer immediately returns his reset push button RS to normal it will efiect closure of the contact 54 thereof, thereby re energizing the device EPV through the circuit for this device heretofore traced. Attention is particularly directed to the fact that de-energization of the device EPV under danger trafiic conditions, as just explained, does not effect sounding of an audible signal, so that the engineer must actually be on the alert to avoid 'a brake application under clanger trafiic conditions, whereas de-energization of the'device EPV under caution traffic conditions as heretofore explained is accompan ied bv the sounding of the whistle W, and reenergization of the device EPV may be-obtained by depressing the push button AN lo cated conveniently to the engineer.

Let us now assume that the Vehicle passes a track ramp under clear trafiic conditions,

it being assumed that the car-carried apparatus is also in its normal clear traflic condltion prior to such passage. As the shoe 20 rides up the incline of the ramp, the shoe contacts 21 and 22 are opened and the shoe contacts 23 and 24 are closed, so that the caution relay CA and the clear relay CL are de-energized, but the device EPV is maintained energized temporarily through the auxiliary circuit including the shoe contact 24. With the shoe 20 engaging the clear ramp TR pulsating current in appreciable quantity may flow through the winding 30 of the main relay MR through the following circuit and inthe direction said circuit is traced :-beginning at the secondary windingof-transformer 27, rectifier 32, winding 30 of the main relay MR,

wire 76, wheels and axle 35, track rails 1, wire 7 5, contact 7 of the repeater relay RR in its raised position, wire 70, contact 10 of the track relay T, wire 71, rectifier 8, wire 7 2, semaphore contact 9, wires 7 3 and-95, con-- tact 6 of relay HR in its raised position, wire 69,,ramp TR, shoe 20, wire 68, back to the secondary winding of transformer 27 For reasons heretofore given the pulsating current in the circuit just traced will be of appreciable value and Will lag behind the voltage inducing it, by reason of the inductance characteristic of the circuit. Also, for reain one direction as much as it does in the other, so that a-small alternating current substantially in phase with the voltage producing it flows in this second circuit.

NVith alternating current of substantially unity power factor flowing in the coil 31 of the relay MR and with the flow of pulsating current lagging appreciably behind the voltage producin it flowing in the coil 30 of the main relay M a torque will be produced in the rotor of said relay MR tending to operate the contact to its right hand position. This movement of contact 80 closesthe following pick-up circuit for the caution relay CA and the clear relay CL beginning at the plus bus, wire 81, shoe contacts 23, wire 82,

polar contact 80 of the main relay MB to the right, wire 97, upper winding of the caution relay CA, wire 98,upper-winding of the clear relay CL, wire 99, upper winding of the signal relay SR, Wire 100, to the minus bus. With this circuit completed the relays CA, CL and SR will all assume their energized position. The relays CA and CL will, as soon as the shoe 20 leaves the ramp TR, have their.

stick circuits heretofore traced again completed, so as to maintain them energized thereafter.

With the relays CA and CL energized and the shoe 2O ret-urnedto its normal position the brake control device EPV is again energized, and by reason of the slow-acting characteristic of the device EPV and the fact that this devce is energized so long as the shoe 20 is in its raised position, its valve will not actually be opened when a train passes a clear ramp; In this connection, if desired, the Shoe contacts 21-23 and 222tmay be of the ficiently long period of time to properly adby olo-se-circuting the same upon the relay SR assuming its-energized position, through the medium of the front contact 103. In other words, the signal relay SR is very quick to pick up, but isvery slow to drop, because the slug 102 is'effectiveto retard a change of flux therein between the time of deenergization of the relay SR and its actual drop- Attention is particularly directed to certain advantages afforded by the system em bodying the presentinvention, In the first V, lay MR. Obviously, if an open circuit should .place attention i'sdirected' to the fact that no wayside source of current srequired for en- .ergizingtheramps TR asis true of certain ramp systems. 'In other words, instead of applying a source of current of 'one polarity or theotlier between the track rail and the track ramp, a rectifier is applied therebetween, with its valve poled in one direction or the other, this rectifier requiring no particular attention and having an extremely long life. Attention is also. directed to the fact that should the rectifier located at a pars ticular track location be short-circuited, for some reason or other, this could not pos- .sibly give a false indication on the car, be

cause the current flow in both windings of the main relay MR would in that instant flow .in circuits having the same inductance charf V acteristics, so that the current flowing in these windings would produce no torque in the re-' occur in the ramp circuit, such asthe breaking of w res 69 or 75, a ClfitIlgGI HldlCltlOIl would be manifested on the tra n, which, al-

I though wrong, would be on the side of safety andiwould notbe as undesirable as a false clear, or false caution 1nd1cat1on.- Further,

should an open circuit appear in one of the multiple paths including windings 30 and 31,

7 current would flow only in one of these windings and no torque would be produced. The system disclosed is one embodying every possible feature of safety, namely, that. all signals function on the side of safetyand if they produce a false control or indication due to Y a failure, such control or indicationmanifests danger, thereby stopping the train unnecessarily rather than letting it proceed due to such failure.

' The rectifiers 8, 8 32 and 33 are preferably vrectifiers of the electrolytic, crystal or copper oxide type in which the rectifying aotionis inherent in the structure of the device. Rectifiers of the vacuum gap thermal 7 type may also befuse'd if desired','especiallyif they do not require external heating of one oftheir electrodes. The rectifiers used shall permit a certain aniount'ofbaokflow, that is, f

leakage in the-opposite direction to thevalve action, thisin order to obtain the alternating current of substantially unity power factor heretofore mentioned; The relay MR should be one of the'two-element induction type, and one which will not produce any torque if the current flow in its two'windings is exactly in phase, and is preferably one in which the magneticstructure for'both windings is the sameso thateach winding associated therewith has the'same inductance as the other winding. c

- Having thus shown and described one rather specific embodiment of the present invention, it is desired to be understood that the specific apparatus and circuit arrangement selected to illustrate the invention has been selected for the purpose of facilitating disclosure of the nature of the invention rather than its scope or the exactconsti-uction preferably employed in practicing the same, and this particular "showing is not intended to exhaust all possible embodiments thereof, and it is to be understood that vari- 1 plied, all without departing vfrom the spirit or scope of theinvention or the idea of means underlying thef-sanie. For instance, the in vention may be applied to'arailway system .of the manual 'block'type, in which event there will be'sub'stituted for. the pole changing contacts (Sand 7, a pole changing switch manually operable by the-.towerman; Also, if desired, the present invention may be ap plied to systems which set up specific speed limits instead of effecting a brake applica-' tion which may be'annulled by the engineer, or if desired, the invention maybe usedfor transmitting two kinds of traflic condition such as proceed and danger instead of three kinds of traflic conditions, :as illustrated. In other words, the presentinvention is not to be limited in any sense, except as demanded by the scope'of the following claims.

What I claim as new is 1. -Trackway apparatus 1 for automatic train control'systems' comprising; a contact ramp; a rectifier; and means for at times including said rectifier in a circuit branch connecting saidramp and the rail of the'railway track to permit the free flow of current from said rail to'said ramp, and at'other timesfin eluding said rectifier in said branch to permit the free flow of current from said ramp to said rail. 1 y w 2; In an automatic'traincontrol system;

the combinationwith a railway 'track'and' a V vehicle movable thereon, of means'for communicatlng. control influences from the track to the'vehicle comprising a circuit including in series a source of alternating current on the vehicle and'a rectifier on the track.

3.-In"a-n' automatic train control sy'ste'ni;

the combination with a railway track and a vehiclemovable thereon, of means for communicating control influences from the track to the vehicle comprising; an electro-responsive means on the car; and a circuit including in series said el-ectro-responsive means, a source of alternating current on the car, and a rectifier on the track.

4. In an automatic train control system; the combinationwith a railway track and a vehicle movable thereon, of means for comn'iunicating control influences from thetrack to the vehicle comprising, electro-responsive -imeans on the vehicle responsive to pulsating current but not responsive to alternating current, a source of alternating current connected in series therewith, and means located responsive to pulsating currents of different polarity but not responsiveto alternating current, a source of alternating current connected' in series therewith, and means located alongithe trackway including a rectiner for at times including said rectifier in series with said source and'electro-responsive means in a mannerto permit pulsating current to flow through said electro-responsive device in one paiticulal directlon and at other times con mes Wlth each of Smd wmdmgs m a manner necting said rectifier in series with said source and electro-responslve means to peri mit the flow of pulsating current in the opposite direction through said electro-responslve means.

6. In an automatic train control system; the combination with a railway track and a vehicle movable thereon; of means for communicating control influences from said track to said vehicle comprising; vehicle carried apparatus including an electro-responsive device responsive'only .to pulsating current, a

source of alternating current connected in series therewith; traclrway apparatus including a rectifier and means partly on the track :and partly on the vehicle for at times conductively connecting said rectifier in series.

with said source and electro-responsive device.

7. In an automatic train control system;

.the combination with a railway track and a vehiclemovable'thereon; and of means for.

including said coils, a source of alternating current connected in serles with said multiple circuits; trackway apparatus includlng a trackway rectifier; and means partly on the track and partly on the car for connecting said trackway rectifier in series with said source and said coils in multiple.

8. In an automatic train control system; the combination with a railway track and a vehicle movable thereon; and of means for communi ating control influences from the track to the vehicle comprising; vehicle car ried apparatus including a polyphase induction type relay having two windings connected in multiple, a rectifier included in se"f ries with each of said windings in a manner to permit the free flow of current in one direction in a circuit including said coils in multiple through one coil and'permit the free flow current in the other direction in such circuit through the other coil, a source of alternating current connected in series with said multiply arranged windings; trackway apparatus including a trackway rectifier;

and means partly on the vehicle and partly' on the track for at times connecting said trackway rectifier in series with said relay and source of current.

9,111 an automatic train control system; the combination with a railway track and vehicle movable thereon; and of means for communicating control influences from the track to the vehicle comprising; vehicle carried'apparatus including a polyphase induction'type relay having two windings connected in multiple, a rectifier included in seto permit the free flow of current in one direction in a circuit including said coils in multiple through one 0011 and permlt the free 'fiow of current in the other direction in such circuit through the other coil, a source of alternating current connected in series with said multiply arranged windings; trackway apparatus including a trackway rectifier; an means partly on the vehicle and partly on the track for at times connecting said trackway rectifier in series with said relay to permit the free flow of current in one direction through said relay and at other times connecting said trackway rectifier in series with said source and relay to permit the free fiow of current in the opposite direction.

10. In an automatic train control system, the combination with arailway track divided into blocks and a vehicle movable thereon; of communicating means including a source of energy on the vehicle for communicating clear, caution, and stop traffic conditions sounding an audible'signal upon each entrance of said vehicle into a clear block, means for applying the brakes in a manner so that the brake application may be annulled by suitable annulling means upon entrance of the train into a caution block, and means for applying the brakes in a manner so that such brake application cannot be annulled by said annullingmeans but can be reset by suitable means after a certain amount of annoyance upon entrance of the train into a stop block.

11. In an automatic train control system, the combination of a railway track and a Vehicle thereon;'of train controlmeans on the vehicle; a source of energyon the vehicle;

. a circuit including said train control means,

said source, and including part of said railway track; and means along the railway track and included in said circuit for changing the character irrespective of Value of the current in said circuit derived from said source inaccordance with traflic conditions in advance of said vehicle. 7

12'. In an automatic train control system, the combination of a railway track and a vehicle-thereon; of train control means on the vehicle; a source of energy on the vehicle; a circuit 1nclud1ng said train control means,

said source, and including part of said railway track, and means along the railway track and included in said circuit for changing thecharacter irrespective of value of the current derived from said source into current of one character or another in accordance with traflic conditions in advance of said vehicle.

13; In an automatic train control system,

the combination of .a railway track and a vehicle thereon; of train control means, on the vehicle; a source of energy on the vehicle; a circuit including said train control means, said source, and including part of said railway track; and means along the railway track and included in said circuit for either interrupting saidcircuit or changing the character of the current derived from said source in accordance with trafiic conditions in advance of said vehicle.

14. In an automatic train control system, the combination of a railway track anda vehicle thereon; of train control means on the vehicle; a source of energy on the vehicle; a circuit including said train control means, said source, and including part of said railway track; and means along the railway track and included in said circuit for either interrupting said circuit or changing the character of the current derived from said source into current of one character or another in" accordance with trafiic conditionsin advance of said vehicle.

In testimony whereof I afiix my signature.

THEODORE BODDE.

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