US2067116A

US2067116A - Train control

Info

Publication number: US2067116A
Application number: US553033A
Authority: US
Inventors: Ned C L Brown
Original assignee: General Railway Signal Co
Current assignee: SPX Corp
Priority date: 1922-04-15
Filing date: 1922-04-15
Publication date: 1937-01-05
Anticipated expiration: 1954-01-05

Description

A Jan. 5, 1937. NQ c.-L. BROWN 'TRAIN CONTROL Filed Apri?. 15. 1922 E miL M\ .We nu@ afl . viding Patented Jan. 5, 19.37

umriss stars GFICE General Railway Signal Company, Gates, N. Y., a corporation of New York `Application Aprill 15, 1922, Serial No. 553,032

4.0 Claims.

` invention relates to automatic train control systems ofV the intermittent type, and particularly to means for transmitting control inuences from the trackway to a moving vehicle.

In automatic train control systems, it is desirable to transmit control influences from the trackway to moving vehicles in accordance with trallic conditions in advance. Such. control inluences are preferably transmitted inductively through an intervening air gap, without physical contact betweenv car-carried and trackway devices..

`One important principle to be observed in construction of safety devices for railroads, is that of the failure on the side of safety. Following out: this principlein an inductive type of train control system, it is expedient to utilize the inlierentrmagnetic properties of a body oi iron along the trackway to produce a stopping or danger influence, so that if wires break, batteries 'become exhausted', or other similar failures occur, the safety o the system will not be destroyed by; .such failures, but the trainwill be stopped thereby. In utilizing thev inherent properties of? iron in trackway devicesoi this kind, suitable vmeans mustl be provided forV removing or counteracting the effect of such devices under clear trac conditions. On the other hand, it is sometimes desirable to provide communicating devices preferably also of the inductive type for transmitting a clearing influence to remove a restriction which has been imposed by such danger or stopping influe-nce. Clearing influences should be transmitted by devices operating on the open-circuit principle, that is, by devices which are constructed so that those portions thereof which are likely to fail, such as a circuit wire and the like, if a failure occurs, will prevent the transmission of a clearing influence. In other words, danger influences should be transmitted by devices along the trackway which have inherent properties which can not fail, the eiect of which may be removed or counteracted by a less reliable device in accordance with trafc conditions; whereas clearing influences should have their 'presence dependent on the less reliable-or weaker links of a chain of the necessary elements. ,i

The present invention is directed toward procommunicatingV apparatus which will transmit suchl danger control iniiuences4 inductively from a` dead orinert trackway device, that is, one which requires no energy in either itsY active or inactive conditon,. and in which an iniiuence may be transmitted to. suitable vehiclethe carried apparatus, if the vehicle moves by such trackway devices, or if it stands over such devices without any relative movement with respect thereto; and is further directed toward the provision of devices constructed on the normally open or deenergized circuit principle for transmitting clearing inuences., these devices likewise being effective with very little or no relative motion between car-carried and track- Way devices.

Other objects and purposes of the invention will appear as the description progresses.

In describing the invention -in detail, reference will be made to the accompanying drawing, in whichr- Figure l shows diagrammatically the trackway of a railway block signal system upon which the trackway apparatus of one embodiment of the present invention has been superimposed;

Fig. 2 shows diagrammatically one form of carcarried apparatus embodying this invention, the parts and circuits being shown more with a View of making it easy to understand the invention and its mode of operation, than with the purpose of illustrating the parts preferably employed in practice; and

Fig. 3 is an enlarged side view of the danger control or knock-down car element.

The danger impulse transmitting means embodying the present invention, comprises in general a track element T, located at desired control points along the track and suitably controlled in accordance with trafiic conditions; and a knockdown car element KD and associated parts cooperating with `said track element T so as to cause interruption of a circuit on the car, or in any other suitable way produce an action on the car Vunder dangerous traine conditions which can be utilized in any of the well-known Ways to regulate the movement oiV trains. The resetting or clearing devices generally comprise a carcarried primary transformer-portion CP supported on a vehicle for communication with a trackway secondary transformer-portion TS, and a trackway transformer-portion TP adapted to communicate at the same time with a car-carried secondary transformer-portion CS, said two trackway transformer-portions being connected in a closed circuit under clear traffic conditions.

Various arrangements of trackway circuits for controlling the condition of the track element T and the transformer-portions TS and` 'I'P may be employed, and in the accompanying drawing there is shownY only one typical arrangement. Referring to Fig. l, the track rails l are divided by insulated joints 2 into blocks in the usual way, one block I and the adjacent ends of two other blocks H and J being shown. Since the parts associated with the various blocks are the same, they will be given like reference characters with distinctive exponents. Each of the blocks is provided with a track battery 3 and a track relay 4, in the same way as in ordinary block signal systems. A train control system embodying the present invention may be used with, or without, the usual fixed signals; and I have illustrated such fixed signals X conventionally, without attempting to illustrate their Well-known control circuits.

The track element T in the specific form. illustrated, comprises a U-shaped yoke or core 5, preferably of a good quality of laminated iron terminating in enlarged pole pieces 6, and which is provided with a coil l. This track element T is located at the appropriate control point at or near the entrance of each block, and in the particular embodiment illustrated has been shown a short distance in the rear of the insulated joints 2. These track elements are preferably disposed lengthwise of the track and on the outside of the rails, so that the pole pieces 6 are disposed a short distance above the surface of the rails. The coil 'I of the track element T is adapted to be closed in a circuit of low resistance by the front contact of a line relay 8. This circuit may be traced as followsz-beginning at the coil l, wire 9, front contact I of the line relay 8, wire II back to the coil 'l of the track element T.

The trackway transformer-portions TS and TP similarly comprise a U-shaped yoke or core I2 terminating in elongated pole pieces I3, and are provided with coils I4 and I5, respectively. These coils under normal or clear traic conditions, as illustrated, are connected in series in a closed circuit, which may be traced as followsz-beginning at the coil I4, wire I8, coil I5, wire i9, front contact I6 of the line relay 8, wire I'I back to the coil I4 of the transformer portion TS.

The line relay 8 is energized when the block at the entrance to which it is placed and also the next block in advance are clear, through a circuit which may be traced as followsz-beginning at the terminal B of a battery, wire 201, front contact 2|1 of the track relay 41, wire 22, front Contact 23 of the track relay 4, wire 24, Winding of the line relay 8, wire 25 to the common return wire C, which is connected to the opposite terminal of the battery. By looking at Fig. 1, it is readily apparent to those skilled in the art that the line relay 8 will only be deenergized when either of the blocks I or J or both are occupied, or are in danger condition, thus putting the track element T and the transformer-portions TS and TP in their active: condition under both caution and danger traffic conditions of the block I.

In describing the car-carried apparatus illustrated in Fig. 2, the several devices will rst be separately described, after which the manner in which they are connected and the operation of the car-carried apparatus will be described. The car-carried knock-down element KD heretofore mentioned, comprises a U-shaped yoke or core 25 terminating in elongated pole pieces 2l and 28, this core being constructed of laminated transformer iron, thus increasing the efficiency of the car element by decreasing the flow of eddy currents and their detrimental effects. One of the legs 29 formed by the U-shaped core 2G is provided with a primary coil P, and the other leg 3B is provided with a secondary coil S.

The U-shaped core 26 is provided with a projection 3l extending parallel to the leg 29 and closely adjacent thereto, so that a shunt magnetic circuit is formed through the leg 29, pole piece 21, projection 3|, core 26 back to the leg 29. This projection 3| is provided with a maintaining coil 32, which is connected in series with the secondary coil S, in a manner so that the voltages induced in these tWo coils due to leakage of ux caused by the primary coil P through the two multiple magnetic paths including said coils, will be opposite or subtractive. This knock-down element KD is preferably mounted on a railway vehicle so that it will have a denite relation with respect to the track rails and track elements, regardless of movement due to the jars and vibrations ordinarily encountered. This is preferably accomplished by mounting said element in a casing to protect it from the weather, this casing being preferably made of non-magnetic material so as not to affect its operation. This casing is preferably mounted from the side frame of a railway truck by a suitable initially tensioned spring device, so that ordinary jars and vibrations will not permit relative movement between theelement and truck, but that such relative movement is possible when severe shocks and jars occur.

The car-carried transformer portions CP and CS each comprise a U-shaped core 33, preferably constructed of laminated iron terminating in enlarged pole pieces 34. The transformer-portion CP is provided with exciting coils 35, and the transformer-portion CS is provided with secondary coils 36. These transformer-portions are supported from the vehicle in a manner similar to that of the knock-down element KD just described.

The car-carried apparatus also includes a control relay CR. This control relay CR may take any one of various forms, but preferably comprises an alternating current electro-responsive device of the two-element type, so that a large amount of energy for actuating this device may be derived directly from a source of alternating current. The moving parts of the relay CR are preferably light and well balanced, so that it will. be quick acting and not affected by jars and vibrations. This relay has been conventionally illustrated, and comprises a local phase Winding 31 and a secondary phase Winding 38 operating a contact 39 against the tension of a spring 40.

A similar relay for responding to clearing or pick-up control influences is provided. This relay has been designated PR, and comprises a local phase winding 4I, a secondary winding 42, and a movable Contact 43 normally biased from a stationary contact 44 by a spring 45. These relays CR and PR, are preferably supported in a heavy casing which is spring supported from the body of the railway vehicle, to protect them from jars, vibrations, and the like.

A suitable alternating current generator AC is provided for energizing the primary coil P, the coils 35 of the transformer-portion CP, and the local phases of the relays CR and PR. This generator AC is constructed and operated to produce an alternating current of the desired frequency. This frequency is preferably reasonably high for reasons which will appear hereinafter.

Since the impulse transmitting means embodying the present invention may be used to control any suitable type of brake or train control apparatus, and since the particular form `of this apparatus forms no part, in itself, of the present inventiomll have illustrated conventionally a device K, in the form of an electro-pneumatic valve which may be used to' vent the train pipe and apply the brakes directly, or govern the operationv of any other form of speed regulating or brake-controlling mechanism. This device K is normally energized,` and is set into operation when deenergized. While the device K may be made so as to be directly operated by the control relay CR, or may be operated by .an intervening repeater relay, for convenience no such intervening repeater relay has been disclosed. A

. Under normal conditions, that is, with a train equipped with the apparatus illustrated in Fig. 2 moving between control points along a track under clear traffic conditions, theprimary coil P will be energized by alternating current from the generator AC, through a circuit which may be traced as follows2--beginning atV the generator AC, wire 46, primary coil P, wire 41 back to the alternating current generator AC. The now of alternating current through the primary coil P produces a comparatively high .alternating magnetornotive-force in the leg 29 of the knock-down car element KD. The coil P is preferably designed ,with reference to the magnetic circuit of the knock-down element KD, so that the flux leaking through the air-gap between the pole piece 21 and the projection 3l, and other paths in multiple therewith, will set up sufficient counter E. M. F. in the coil P to reduce the current owing therein to anV amount necessary to produce said ilux without undue heating of this coil. In other words, the current flowing is that necessary to produce a certain alternating flux plus that necessary to overcome the iron and copper losses, that is, it is the exciting current.

The magnetic circuits of the knock-down element KD are so designed that ra large percentage of the flux will leak through the projection 3| and maintaining coil 32, thereby inducing a voltage in this maintaining coil 32. A small amount of flux will also leak from one to the other of the pole pieces 21 and 2B through the secondary coil -S back through the back yoke of the core 26` to the leg 29. This alternating leakingv ux will induce a small voltage in the coil S which is in opposition to the voltage induced in the maintaining coil 32, this voltage, however, being so small as compared with the voltage induced in the maintaining coil, that the voltage induced in the maintainingY coil predominates thereover, thus causing a current to flow in the circuit through `the secondary phase Winding 38 in the direction `52, local phase winding 31 of the control relay CR, wire 53, front contact 54 of the control relay CR, wires 55 and 56 back to the alternating current generator AC.

With the two windings of the control relay CR energized in the manner as just described, the front contact 39 will be maintained in its closed position, as illustrated, against the tension of the spring 40. The phase relation between the curl rents in the local phase winding 31, and secondary energized by alternating current from the genert;

ator AC flowing through a circuit, which may be traced as follo-wsr-beginning at the generator AC, wires 5l, 51 .and 58, winding of the device K, wire 59, movable contact 39 of the control relay CR, Wire 55 and` 5B back to the alternating current generator AC. With the device K energized the train may proceed without ,any restriction.

The restoring or pick-up relay PR is connected so that it will be energized when alternating current is induced in the secondary coils on the carcarried secondary transformer-portion CS, and controls a circuit which bridges the contacts included in the stick circuit of the control relay CR. The circuit for energizing the local phase winding of the pick-up relay PR may be traced as followsz--beginning at the generator AC,

wires

5I, 51 and 60, local phase winding 4l of the pick-up relay PR,

wires

5l, 52 and 56 back to the generator AC, 'Ihe secondary phase winding of the pick-up relay PR receives its energy through the il' transformer portions CP and CS mounted on the railway vehicle, and the cooperating transformer portions TP and TS located along the trackway, as heretofore described, the Vprimary transformer-.portion CP being energized by a circuit which may be traced as followsi-beginning at the generator AC, wire 65, coil 35 or?V the primary transformer-portion CP, wire 55, the other coil 35 of said transformer-portion, and wire 66 back .to the generator AC.

The energizing circuit for the secondary'phase winding of the pick-up relay PR may be traced as followsz-beginning at th-e coil 36 oi the transformer-portion CS, wire 5S, coil 35, wire 58, secondary phase winding t2 of the pick-up relay PR, wire 10 back to said coil 35.

Referring particularly to Fig. 2, let us assume that a railway vehicle equipped with this apparatus in its normal condition is moving along the trackway so that the knock-down element KD passes over a track element T, having its winding 1 open-circuited, because the block at the entrance to which it is placed, or the next block in advance thereof, is occupied and the line relay 8 is deenergized. During the period Vof time that the pole pieces 21 and 28 of the knock-down element KD are -directly over the pole pieces (i of the track element, the reluctance through the U-shaped core 26 will be much reduced due to the presence of the track element T. This reduction of the reluctance through the magnetic circuit just mentio-ned causes .an increase of alternating ilux through the secondary coil S, and at the same time causes a reduction of the alternating flux through the projection 3|. This reduction of the alternating magnetic flux through the projection 3i is accounted for by the fact that the total flux through the coil P is not changed materially, because this alternating flux Yis that which is necessary to produce the necescurrent flowing therein. Or in other words, the alternating flux is dependent on the voltage impressed on the primary coil P and is practically independent of the reluctance of the magnetic circuit through this coil, that is, when the reluctance through the element KD is reduced the magneto-motive-force induced in the primary coil P is correspondingly reduced which, of course, will reduce the leakage flux through the projection 3i.

Since, now, the alternating iiux passing through the secondary coil S has been materially increased, and the alternating flux passing through the maintaining coil 32 has been materially reduced, the current flowing due to the two opposing voltages induced in these coils may have been reduced substantially to zero, or may even have been reversed, dependent upon which of these two voltages predominates. In any event, the several parts are so designed that when the element KD passes over a track element T when in its eifective condition, the torque of the control relay CR will be either much reduced or will be reversed. The momentary deenergization of the control relay CR allows the front contact 39 to be broken, thereby opening the circuit through the local phase winding 31 of the control relay CR, thereby deenergizing it entirely and permanently, this being a stick circuit. Further, the dropping of the front contact 39 also interrupts the circuit through the device K which interruption will cause K to be actuated to control the train in a manner dependent upon the device K and the apparatus controlled thereby.

The train may now proceed through the block restricted by the train control device K. Let us assume that during the time the train passes through the block at a restricted speed that the two blocks next in advance thereof have become clear. This will, of course, cause the line relay 3 at the entrance of the next block in advance to be maintained energized, thereby coupling the coils of the two trackway transformer-portions TS and TP together through the circuit heretofore traced. During the time the car-carried transformer-portions CP and CS are in communicating relationship with the trackway transformer-'portions TS and TP, respectively, a chain of energy transmitting and transformer devices is completed, whereby the secondary phase winding t2 of the pick-up relay PR is energized by alternating current from the generator AC. This chain of devices comprises a transformer consisting of the transformer portions CP and TS having their magnetic circuit completed through air gaps, and this transformer ener-gizes another transformer consisting of transformer-portions TP and CS having a similar magnetic circuit, this transformer being connected to the secondary phase Winding 42 of the pick-up relay PR. Consequently when, and only when, this chain of devices is completed, energy will be supplied to the secondary phase winding 42 of the pick-up relay PR; and since the local phase winding thereof is continuously energized, the relay will be actuated closing its contact and completing a pick-up circuit. Obviously, this is only possible when the line relay is energized, which is only true when the adjacent block and the next block in advance are clear.

This pick-up circuit may be traced as follows: beginning at the generator AC, wires 5l and 52, winding 31 of the control relay CR, wires 53 and 1l, front contact 43 of the pick-up relay sary counter E. M. F. in the coil P to limit the PR,

wires

44, 62 and 56 back to the generator AC. The completion of this circuit will energize the control relay CR momentarily, thereby completing its stick circuit heretofore traced. This Vwill permanently energize the control relay CR which in turn will energize the train control device K, thereby removing the restriction enforced by this device, which only depends on its design and construction as heretofore explained. In any event, the train may now again proceed unrestricted by the train control device K.

Assuming now that a railway vehicle passing along the trackway with the car apparatus in its normal condition in the same manner as heretofore described is passing over a track element T when in its clear traifc condition, that is, with its coil l closed in a circuit of low resistance through the front contact Ill of the line relay 8. During the time that the knock-down element KD has its pole pieces 21 and 28 over the pole pieces 6 of the track element T, a small amount of ux will leak through the U-shaped core of the element KD and the core 5 of the track element T. This small amount of alternating flux will cause a relatively large alternating current to be set up in the winding 1, thereby producing an opposing alternating magneto-motive-force which will prevent a stronger iield of flux from passing through this magnetic circuit. The slight amount of additional alternating flux passing through the secondary coil S will increase the voltage induced in this coil slightly, thereby reducing the current flowing in the secondary phase winding 38 to a certain extent. This slight decrease of current will, however, be insufcient to cause the control relay CR to be actuated, therefore not aifecting the operation of the train control device.

Car-carried apparatus of an inductive influence transmitting means has, therefore, been provided which will transmit a danger or knockdown inuence when passing over a track element comprising an inert mass of iron, but which will not transmit an influence if such a mass of iron is passed over when provided with a coil closed in a circuit of low resistance, the functioning of this means being dependent upon an alternating flux, therefore enabling it to function when the device is in communication with a track element in its effective or open-circuit condition continuously, that is, when standing over it, as well as when it passes thereby at a comparatively high rate of speed. Further, the apparatus embodying this invention includes devices for restoring or picking up the devices actuated by such a knock-down influence when traflic conditions again clear up, the restoring device likewise functioning through an air gap without any physical contact between the trackway and car-carried devices; and employing alternating current so that the device will function, regardless of whether the car-carried and trackway devices are in constant communication, or whether they are passing by each other at a commercial train speed, providing the traflic conditions are such that a pick-up influence should be transmitted.

It should also be noted that the car-carried apparatus for transmitting knock-down influences is constructed entirely on the closed energized circuit principle, for instance, if the circuit through either of the phase windings of the controy relay CR is interrupted, the device K will be actuated, thereby enforcing a restricted speed in a manner dependent upon this device. If the exciting circuit Vof the primary coil P should be interrupted, no current would be induced in the secondary phase winding 38 of the control relay CR, thereby actuating the device K in a similar manner; and likewise if the alternating current source should entirely fail, or only the circuit for energizing the train control device K should fail, this device would be actuated to enforce a restriction dependent on said device. Likewise, if the circuit `including the coil of the track element T should not be intact for any reason, a knock-down influence will be transmitted, because the inherent properties of the iron core of this element can not fail. On the other hand, that portion of the automatic train control apparatus which is necessary to restore the train control device K is, as it should be, entirely designed and constructed on the open-circuit principle, so that a failure of any one of the circuits included in this apparatus will prevent the transmission of a restoring infiuence, thereby making it impossible to transmit a false restoring or proceed influence due to failure. This is readily apparent by noting that Veach portion or link of the chain of devices heretofore mentioned is necessary to transmit a restoring or proceed inuence, and consequently if any one of them should fail, no such influence can be transmitted.

A relatively high frequency is preferably employed in order that o-ne, or more, cycles may transpire during the time the car-carried and trackway devices are in communication during the passage of a train at high speed, this being desirable because the control relay should respond to such communication under danger trafc conditions, and at the same time should not be actuated when the alternating current which maintains'it energized passes through zero. Another advantage in employing such a frequency, resides in the fact that the magnetic properties of the track element T, as compared with such properties of crossing rails, increase with the frequency used. This, it is believed, is due to the quality of the iron used and its laminated structure. The employment of such relatively high frequency, therefore, it is believed, improves the operating characteristics of the apparatus itself, and also increases the marginal effect the track element produces over that of a crossing rail.

It should be noted that lthe apparatus employed for the transmission of knock-down influences has been mounted on the righthand side of the track, considering trailic in the direction of the arrow, and that the devices for transmitting pick-up or proceed influences have been mounted on the lefthand side of the trackway. This has been done so that the car-carried devices provided for one purpose can not get into communication with the trackway devices provided for the other purpose. Further, duplicate equipment may be provided on the vehicle so that either end of the vehicle may run ahead, automatic means being provided to cut in the proper set of devices, the operation of said automatic means being dependent on the direction of movement of the train. This may be accomplished by an obvious adaptation of the means described in the co-pending application No. 544,561, led March 17, 1922, by Charles S. Bushnell.

While I have described only one specific embodiment of the invention, I desire to have it understood that the particular construction shown and described may be modified and adapted to meet the various demands for communieating devices in automatic train control systems without departing from the spirit and scope of the present invention. f

What I claim as new and desire to secure by Letters Patent, is:-

l. Influence communicating means for automatic train control systems comprising, a car element having two partial magnetic circuits, means for producing a substantially constant alternating flux in said element, and trackway means including adjustable electrical means for at times shifting flux from one to the other of said partial magnetic circuits.

2. A car element for receiving inductive inuences from the trackway comprising, a threelegged yoke of magnetic material, means for producing an alternating magnetto-motive-force in one of said legs, and means for detecting the respective amounts of flux in the other two legs.

3. A car element comprising, a yoke having two partial magnetic circuits, means for producing an alternating magneto-motive-force in said circuits, and a Winding magnetically associated lwith each of said partial magnetic circuits, said windings being connected in series so that the voltages induced by said magneto-motive-forces will be in phase opposition.

4. In an automatic train control system, the combination of means for transmitting danger control influences comprising, car-carried devices and circuits in which each circuit is energized by alternating current and adapted to be actuated by trackway devices each comprising q a bar of iron when in its active condition and means for controlling each to an inactive condition; and means for transmitting restoring influences comprising, car-carried and trackway transformer-portions which are energized from a source Vof alternating current on the vehicle and which act under clear tramo conditions to transmit a restoring inuence.

5. Inductively acting inuence communicating means for automatic train control systems comprising, a receiving element on a car including three magnetically coupled coils, a source of alternating current on the car energizing one of said coils, an electro-responsive control device connected with the other two coils in series and normally energized by current induced therein from the energized coil, one of said two other coils being only weakly excited and opposing the excitation of the other coil, and a track element including a magnetic core for at times increasing the excitation of the weakly excited coil, thereby opposing the excitation of the strongly excited coil and producing a reduction in the energizing current normally supplied to said control device.

6. In a train control system, the combination with a car-carried source of alternating current, automatic means partly on the vehicle and partly on the track deriving its energy wholly from said source for communicating two distinctive initiating and restoring control influences through an intervening air gap at predetermined control points along the track, said means including two separate tramo controlled circuits on the trackway for respectively determining the communication of said influences, one circuit if open causing the transmission of the initiating influence and the other circuit if closed causing the transmission of the restoring inuence, and automatic brake control apparatus initiated and restored by said inuences.

7. In a train control system, the combination with safety apparatus on a vehicle adapted when initiated to continue to be effective until restored, of means initiating the operation of said safety apparatus dependent on traffic conditions and including a track device constituting an inert magnetic body when in its active stopping condition, means for restoring said apparatus comprising, a source of alternating current on the vehicle, a trackway circuit, and cooperating carcarried and trackway devices energized from said source and eifective at predetermined control points only if said circuit is closed.

8. Car-carried means adapted to be influenced by a cooperating track element constituting a magnetic body and comprising, a source of alternating flux, two partial magnetic circuits supplied from said source, and electro-responsive means operable upon a predetermined change in the relative reluctance of said magnetic circuits and means including adjustable electrical means to change said relative reluctance.

9. In a train control system, the combination with a track device constituting an inert magnetic body when in the active stopping condition, car apparatus cooperating with the track device and comprising, a magnetic core, a primary coil on the core constantly energized by alternating current, a secondary coil on the core energized from the primary coil by transformer action, a third coil magnetically associated with the primary coil and included in a path normally of higher magnetic reluctance than that through the secondary coil, and electro-responsive means connected with the secondary and the third coils in series, the track device acting to decrease the reluctance of the magnetic circuit through the secondary coil but not the third coil.

10. A car element for train control systems comprising, a source of alternating current, two partial magnetic circuits of normally different reluctance both energized from said source, and two oppositely wound coils connected in series and contained one on each of said magnetic circuits.

11. In a train control system, the combination with a track element having a U-shaped magnetic core and a winding thereon, trackV circuit controlled means for placing said winding in a closed deenergized circuit of low resistance under clear traffic conditions and on open circuit under dangerous traic conditions, a car element having a magnetic core arranged to come in superimposed relation with the core of said track element, a source of periodically fluctuating current on the car, an exciting coil on said car-carried core energized from said source, a secondary coil on said car-carried core in which voltage is induced as that core comes over the core of the track element with its winding on open circuit, and electro-responsive means normally energized from said source and having its energizing current reduced by the voltage induced in said secondary coil.

12. In a train control system, the combination with a source of alternating current on a vehicle, of separate initiating and restoring receiving devices on the car moving in diierent paths along the track and both energized wholly from said source, and track circuit controlled trackWay devices separately cooperating with said receiving devices and effective to produce thereby initiating and restoring influences, respectively, independently of the speed of the car.

13. In a train control system, car-carried brake control apparatus adapted when set into operation to continue to be effective until restored, a source of alternating current on the car, means including a track device constituting an inert body of iron when in the active stopping condition for at times under dangerous traffic conditions setting said brake control apparatus into operation, a normally deenergized circuit adapted when energized to restore said apparatus, and two pairs of cooperating car-carried and wayside elements effective only if a trackway control circuit is closed for energizing the circuit on the car by transformed energy derived from said source.

14. In a train control system, the combination with a source of current on a vehicle, separate initiating and restoring receiving devices on the vehicle moving in different paths along the track, and traflic controlled track devices separately iniiuencing said receiving devices, said receiving devices and track devices deriving their energy wholly from the source on the vehicle and having their effective action dependent upon a series of normally energized circuits and a series of normally deenergized circuits, respectively.

15. In an inductive impulse communicating means for train control systems, the combination of a car element having a coil normally energized by alternating current, electro-responsive means on the car normally maintained inactive by the flow of alternating current in said coil of the car element, said car element having another coil adapted to have voltage induced therein at times by ux derived from the normally energized coil, the voltage induced in said another coil causing deenergization of said electro-responsive means, and a track element cooperating with the car element and causing such induction of voltage in said another coil to actuate the electro-responsive means, the frequency of said alternating current being high enough to allow one or more cycles to take place during the period of effective cooperation of the car and track elements at the highest speed of the car.

16. A car element for automatic train control systems comprising, a yoke of magnetic material of a conguration resulting in two partial magnetic circuits one of which has a lower reluctance than the other, means for continuously supplying undulating ux to said circuits, and trackway means having means for varying the electrical characteristics of the trackway means.

17. Inductively acting influence communicating means for automatic train control systems comprising, a receiving element on a car including magnetically coupled conductors, a source of alternating current on the car energizing one of said conductors, an electro-responsive control device connected with the other of said conductors in series and normally energized by current induced therein from the energized conductor and a track element including a magnetic core for at times varying the excitation of the other conductor for producing a reduction in the energizing current normally supplied to said control device.

18. A car element comprising, yoke means forming two magnetic circuits, means for producing an alternating magneto motive force in the circuits, and a winding magnetically associated with each of said circuits and connected in series so that the voltages induced by said magneto motive force will be in phase opposition.

19. In a train controlling system, a primary coil on the vehicle continuously energized by alternating current, a closed circuit on the vehicle including` secondary coils of unequal-voltages and connected in opposition, a relay on the vehicle normally energized by the diierence between the voltages; an armature on the roadway adapted to form a path of low reluctance for the flux of the primary vehicle coil as the vehicle moves past said armature, and means to control the magnetic characteristics of the armature, in accordance with different track conditions.

20. In a train controlling system, a primary coil on the vehicle continuously energized by alternating current, secondary coils on the vehicle connected Vin opposition in a closed electric circuit, relay means on the vehicleadapted to be operated by the difference between the voltages of said secondary coils, a brake control magnet on the vehicle; an armature on the roadway adapted to form a path of low reluctance for the flux of the primary vehicle coil as the vehicle moves past said armature, and means for varying the Voltage in the secondary vehicle coils in acthe armatures in accordance with different track` conditions.

22. In a train controllingsystem, a primary coil on the vehicle continuously energized, secondary coils on the vehicle connected in opposition, relay means on the vehicle energized in accordance with the differential current in said seconda-ry coils; armatures on the roadway adapted to form a path of low reluctance for the magneticv ilux ofthe vehicle coils each time the vehicle moves past one of said armatures, and coil means on `the armatures adapted to control the iiux through the armatures, in accordance' with different track conditions.

23. In a train controlling system, a primary coil on the vehicle continuously energized; secondary coils on the vehicle associated with said primary coil and connected in opposition; relay means on the vehicle normally energized by the currents in said secondary coils; a plurality of insulated block sections constituting a track for said vehicle; an armature associated with each block section over which said vehicle coils may pass and forming a path of low reluctance for the magnetic flux of said vehicle coil; and magnetic means .associated with each armatureY adapted to control its magnetic characteristics.

24. Influence communicating means for automatic train control systems comprising, a carcarried ycore having a primary coil thereon normally energized byv alternating current, a secondary coil on `said core disposed adjacent said coil, a secondary bucking coil on said core located a considerable distance from said primary coil and connected in series with said secondary coil, and traffic controlled trackway means for reducing the reluctance of the magnetic circuit including said primary coil and said bucking secondary coil under predetermined traffic conditions ahead. i

25. Inuence communicating means for automatic traincontrol systems comprising, a carcarried core having a primary and a secondary coil thereon, said primary coil being energized by alternating current, a control relay having a front contact, an energized circuit for said control relay including the winding and front contact of said relay and said secondary coil, and means partly on the vehicle and partlyalong the trackway for inducing a voltage in said circuit.

26. Influence communicating means for automatic train control systems comprising, car-carried apparatus including a control relay, a core, a primary and a secondary coil on the core,a bucking secondary coil on the core and connected in series with said secondary coil, means for continuously energizing said primary coil by alternating current whereby a voltage is induced in said secondary coil predominating over the opposed voltage induced in said secondary bucking coil, thus producing a current for maintaining said relay energized, and trackway means for de-energizing said relay by increasing the voltage in` said secondary bucking coil without materially increasing the voltage in said secondary coil, whereby a systeml is formed in which a failure of energizing current for said primary coil causes de-energization of said relay.

27. Influence communicating means for automatic train control' systems comprising, a carcarried core, having a primary coil thereon normally energized by alternating current derived from 'a car-carried source, a control relay, another coil on said core, a circuit including the winding of said control relay and said other coil, means for inducing a voltage in said circuit to maintain said relay energized, and traic controlled trackway means for inducing a voltage in said other coil to de-energize said relay.

28. Influence communicating means for automatic train control systems comprising, a carcarried core having a primary coil thereon normallyV energized by alternating current, a secondary coil on said core disposed adjacent said coil, a secondary bucking coil on said core located a considerable distance from said primary coil and connected in series with said secondary coil, and tra-nic controlled trackway means for diverting flux passing through said primary and secondary coils from leakage paths through said secondary bucking coil.

29. Car-carried apparatus for automatic train control systems of the intermittent inductive type, comprising a primary coil, two secondary coils connected in series, a source of alternating current for energizing said primary coil,V train control means having two windings one of which is connected in series with said secondary coils and a contact closed when said train control device is energized, said secondary coils being located with respect to said primary coil to cause more alternating flux to link one Secondary coil than the other and to cause the flux to induce opposing voltages in the circuit of said secondary coils thereby inducing sufficient current in said one winding of said train control device to maintain it energized, trackway means active under adverse tralicV conditions ahead to cause ux linking said one secondary coil to be diverted to link the other secondary coil and cause de-energization of said train control device, and `other trackway means effective under clear trafiic conditions ahead to produce a ovv of current in the other winding of said train control means for restoring it to normal.

30. Car-carried apparatus for automatic train control systems Vof the intermittent inductive type,

comprising a primary coil, two secondary coils connected in series, a source of alternating current for energizing said primary coil, train control means having two windings one of which is connected in series with said secondary coils and a contact closed when said train control means is energized, said secondary coils being located with respect to said' primary coil to cause more alternating flux to link one secondary coil than the other and to cause the flux to induce opposing voltages in the circuit of said secondary coils thereby inducing suiiicient current in said one winding of said train control means to maintain it energized, trackway means comprising an inert magnetic body when in its active condition and active under adverse traic conditions ahead to cause ux linking said one secondary coil to be diverted to link the other secondary coil and cause de-energization of said train control means, and other trackway means effective under clear traffic conditions ahead' to produce a flow of current in the other winding of said train control means for restoring it to normal.

31. A cab carried source of altern-ating current, a differential inductor designed to be continuously energized by said current and provided with two magnetic paths, a rst path of normally lesser and a second path of normally greater reluctance, a tr-ain stop means normally sustained in a predetermined position by flux in the first path, and a track element designed to reduce the reluctance of the second path below that of the rst path when desired and thus operate the train stop means.

32. In an intermittent inductive train control system, the combination with a car-carried receiver having a magnetic structure with two partial magnetic paths, each path including a separate air gap, said paths being respectively of greater and lesser reluctance, a car-carried source of alternating current, a winding on said receiver constantly energized from said source and supplying alternating flux to both of said magnetic paths, a secondary coil on the receiver linked by the flux in the magnetic path of lesser reluctance, an electro-responsive device on the car electrically connected to said secondary coil and normally energized by the current induced therein by the alternating current in said constantly energized Winding, a track inductor acting upon movement of the receiver thereby to decrease the reluctance of said magnetic path of the receiver having the greater reluctance and thereby reducing the current in said secondary coil and causing operation of said electro-responsive device, a winding on said track inductor, and means for at times connecting said track inductor winding in a closed circuit.

33. In an intermittent inductive tr-ain control system, the combination with a car-carried receiver having two partial magnetic paths of diiferent magnetic reluctance, each of said magnetic paths having an air gap therein, a source of alternating current on the car, a Winding on the receiver constantly connected to said source for exciting both of said magnetic paths with alternating uX, secondary coils on the receiver respectively linked by the ux in said magnetic paths and each having a voltage induced therein by the constantly energized Winding dependent upon the reluctance of its corresponding magnetic path, electro-responsive means on the car responding to the diierence in the voltages induced in said secondary coils, a track inductor acting upon movement of the receiver thereby to reduce the reluctance of the magnetic path of the receiver having the greater reluctance and thereby causing operation of said electro-responsive means, a winding on said track inductor, and means for at times connecting said winding of the inductor in a normally closed circuit.

34. A train control system comprising the following combination; a train-carried source of alternating current and associated signal-receiving circuit, a train-carried unit for transmitting current to and receiving current from the Wayside comprising inductor coils and' means whereby the source impresses two opposing E. M. F.s upon the receiving circuit for the purpose of increasing the sensitivity of the receiving circuit to the influence of a wayside circuit, together with a w-ayside system which includes coils functioning simultaneously to receive current from and transmit current to the train, and relay signal control means.

35. In combination, vehicle carried mechanism, a vehicle carried inductor means including an energizing inductor associated with and adapted to be influenced for tripping the said vehicle carried mechanism, a second vehicle carried inductor means including an energy receiving inductor associated with and adapted to be influenced for resetting the vehicle carried mechanism and a roadside inductorium means operable in response to a given roadside condition for influencing the first mentioned inductor means to produce the tripping action and operable in response to another roadside condition for influencing the second vehicle carried inductor means to produce the resetting action when the vehicle carried mechanism has been tripped and being inoperative under such last mentioned condition for producing any change in said vehicle carried mechanism when the said vehicle carried mechanism has not been tripped.

36. In combination, vehicle carried mechanism, a vehicle carried inductor means including an energizing inductor associated with and adapted to be influenced for tripping the said vehicle carried mechanism, a second vehicle carried inductor means including an energy receiving inductor associated with and adapted to be iniiuenced for resetting the vehicle carried mechanism and roadside inductorium means operable in response to a given roadside condition for influencing the rst mentioned inductor means to produce the tripping action and operable in response to another roadside condition for inuencing the second vehicle carried inductor means to produce the resetting action when the vehicle carried mechanism has been tripped and being inoperative under such last mentioned condition for producing any change in said vehicle carried mechanism when the said vehicle carried mechanism has not been tripped.

37. In a train control system, in combination, a signal circuit, a car-carried source of A. C., a car-carried receiver, a primary winding on the receiver energized from said A. C. source, a secondary winding on the receiver inductively related to the primary and arranged to control the signal circuit, the primary winding being arranged to send flux through the secondary winding in a manner to produce opposing E. M. F.s in the secondary winding, and a wayside inductor to cooperate with the receiver.

38. In a train control system, in combination, a signal circuit. a car-carried source of A. C.,

a car-carried receiver including a primary winding energized from said A. C'. source, and a secondary winding included in a circuit and inductively related to the primary winding and controlling the signal circuit, the primary winding being arranged to produce twoopposing current producing inuences upon the circuit of the secondary winding, and a wayside element for inuencing the action between the primary and secondary windings.

39. In a train control system, in combination, a car-carried source of A. C., a car-carried receiver including a primary winding and an inductively related secondary winding, the primary winding being connected to the A. C. source, the secondary winding being included in a controlling circuit, the primary winding being arranged for producing two A. C. uxes one only of which may dominate to produce an A.

20 C. current in the controlling circuit, and a Wayside inductor for Varying the inductive relationship between the primary and secondary windings.

40. In combination, vehicle carried mechanism comprising a control relay, a transformer including primary and secondary coils associated therewith, the said primary coil being adapted to be influenced for producing a predetermined operation of said relay, a resetting circuit for said relay, an indication receiver for operating the resetting circuit and a Vehicle inductor adapted to Vbe influenced for operating the indication receiver; and roadside mechanism comprising roadside inductor means operable in response to a given roadside condition for inluencing said primary coil and operable in response to another roadside .condition for being energized for inuencing the said vehicle carried inductor.

NED C. L. BROWN.