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Publication numberUS2554056 A
Publication typeGrant
Publication dateMay 22, 1951
Filing dateJun 20, 1947
Priority dateOct 23, 1946
Publication numberUS 2554056 A, US 2554056A, US-A-2554056, US2554056 A, US2554056A
InventorsGoldie Shipp Douglas, Hurst Peter Leslie
Original AssigneeUnion Switch & Signal Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Multiple frequency intermittent inductive cab signal and automatic train control system
US 2554056 A
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Description  (OCR text may contain errors)

y 22, 1951 L. H. PETER ETAL 2,554,056

MULTIPLE FREQUENCY INTERMITTENT INDUCTIVE CA 1 SIGNAL AND AUTOMATIC TRAIN CONTROL SYSTEM Filed June 20, 1947 &

N INVENTORS Lariz'eflam/Pefep and Patented May 22, 1951 MULTIPLE FREQUENCY INTERMITTENT IN- DUCTIVE CAB SIGNAL AND AUTOMATIC TRAIN CQNTROL SYSTEM Leslie Hurst Peter and Douglas Goldie Shipp,

London, England, assigncrs, by mesne assignments, to The Union Switch. and. Signal'Company, Swissvale, Pin, a corporation of Pennsylvania Application June 20, 1947, Serial No. 755,854 In Great Britain October 23, 1946 19 Claims. 1

This invention relates to intermittent inductive train control systems of the alternating current type, in which wayside inductors located on the trackway are arranged to influence receiving apparatus on a vehicle so as to effect the control or operation of mechanism on the vehicle to give signal indications, and if desired, to control the train brakes, the trackway inductors comprising circuits adapted to be tuned to differentfrequencies for this purpose in accordance with the signal aspect of one or more track signals or a control transmitted from any desired point or automatically in accordance with trafiic conditions.

In systems of this charact'er previously proposed it has been necessary to provide a source of energy to energize the trackway inductors in order that they may at times influence the re.- ceiving apparatus on. the vehicle in the desired manner. This, as is evident, is. a disadvantage, especially where it is desired to employ a plurality of frequencies, in that. it entails the installation of a large amount of apparatus. In the system of. the present. invention this disadvantage isv overcome. and according to the principal feature of the invention the trackway inductors. are arranged toinfluence receiving apparatus onthe vehicle when deenergized or when energized by currents the sources of supply for which are carried to the vehicle.

According to a further feature of the invention.

two separate sets of receiving apparatus are pro.- vided on the vehicle, both being adapted to be responsive to the influence of the same trackway inductor, one set, which is adapted to give proceed signal indications being of the normally inactive or zero current output type, while the other set is adapted to give stop signal indications and is of the normally active type, for the purpose of insuring increased safety in operation.

According to a further feature of the invention the stop signal indication mechanism may be combined with or may control arrangements for eiiecting an automatic application. of the brakes of'the vehicle or train.

One form of apparatus embodying the invention will now be described and the novel features thereof will then be pointed out in claims.

Referring to the accompanying drawing, Fig. 1 illustrates one form of apparatus embodying the invention, and Fig. 2 contains a typical track plan of a stretch of railway track equipped with block signals and illustrates how the apparatus is coordinated with the block signaling system.

Similar reference characters refer to similar parts in both views.

Referring to Fig- 2, in the preferred embodiment of the invention, an inductor I situated as shown within or adjacent the trackway, comprises a core of magnetizable material provided with a winding 2 adapted to be bridged by oneor more of a plurality of tuned circuits 3, each comprising. a series connected reactor and condenser. Each circuit is tuned to resonance at a different frequency fl, f2 or f3, as indicated by the legends adjacent the tuned circuits 3, and the number of such frequencies will depend uponv the number of signal aspects which can be displayed by the associated wayside signal. For example, if the signal is arranged to display four aspects, green (G) double yellow (Y -Y), yellow (Y) and red (R), as illustrated for the signals which govern train movements into the successive block sections 4T, 3T, 2T and lT, in the rear of a train V, three resonant circuits will be employed tuned to frequencies fl, (G), f2 (Y-Y) and f3 (Y) respectively. Contacts 4 operated by the signal, or by apparatus controlling the signal, are arranged to bridge the winding of the trackway inductor l with one or other of these resonant circuits in accordance with the proceed aspect displayed by the signal and to open circuit the track inductor winding in the event that the signal displays astop (R) indication.

Mounted on the locomotive or other vehicle are two receivers 5 and 6, arranged as shown in Fig. 1 to pass successively over inductor I. Receiver 5 is adapted to control the signal indication device 1 in. the cab of the vehicle, while receiver 6 is employed to provide an automatic application of the brakes if the train should pass a signal which displays a stop indication. The output of receiver 5 is arranged to be zero except when passing over a trackway inductor tuned to a frequency fl, f2 or I3, While the receiver 6 has a normally active output. Receiver 5 will be termed the cabsignal receiver. and receiver 6 the train-stop receiver.

The reason. for providing the two separate receivers, one normally inactive and the other normally active, is to conform to the well-known requirement of railway signaling systems that any failure of the apparatus to function normally must not result in a dangerous condition. The manner in which this is achieved will become apparent as-the description proceeds.

The cabsignal receiver 5 is of the normally balanced. magnetic bridge type provided with one or more primary windings 8 which are supplied with currents of frequencies 1, f2 and f3 through the tuned circuits 9, by a suitable source carried on the locomotive and. illustrated typically as a motor-generator set l0, these frequencies corresponding to the frequencies to which the resonant circuits 3 associated with the trackway inductors are tuned. A. secondary winding II is arranged 3 at times to supply energizing current to One or other of three quick acting direct current relays Fl, F2 and F3 through frequency selective circuits l2 tuned to frequencies fl, f2 and f3 and rectifiers l3. The receiver 5 is of the same general type as that disclosed in the Letters Patents of the United States to Paul N. Bossart, No. 1,773,297 issued August 19, 1930, and No. 1,843,477, issued February 2, 1932. The windings of the receiver 5 are mounted on cores of magnetizable material separated by the air gaps a, b, c and d, the reluctance of which is relatively so high in comparison with that of the core material that the distribution of the magnetic flux is determined almost wholly by the air gaps, and the reluctance of the iron portions may be disregarded. The air gaps are so proportioned that when air gap c is not modified by the proximity of a wayside inductor I, the ratio of the reluctance of the air gap to that of the compensating air gap 11 is equal to the ratio of the reluctance of air gap d to that of air gap b. Winding 8 is constantly energized by currents of the three frequencies mentioned, and it will be evident that the parts are so proportioned that normally the magnetomotive forces due to these currents will produce a magnetic flux in the core which will divide between air gaps a and c in the same ratio as between air gaps b and d. In other words, one part of the flux will pass through air gaps a and b and the remainder through air gaps c and d. The magnetomotive force due to the primary current of each frequency is thus impressed upon the four air gaps in such a manner that these constitutethe four arms of a magnetic bridge, and they are so proportioned that the bridge is normally balanced, consequently the primary fluxes normally do not pass through the portion of the secondary core upon which coil II is mounted and the output of the secondary winding ll is normally zero so that the three quick acting relays Fl, F2 and F3 are normally deenergized. When the receiver 5 comes into alignment with an inductor I tuned to frequency fl, for example, winding 8 is inductively coupled to winding 2 and causes current of frequency fl to build up therein to its resonance value, producing an opposing inagnetomotive force which is impressed across the arm c of the bridge and maintains the bridge substantially in balance with respect to this frequency, consequently relay Fl remains deenergized. The fluxes of frequencies f2 and f3 however will pass freely through the core of inductor l and the reluctance of arm 0 of the bridge will be materially decreased, with respect to these frequencies. The receiver 5 will then become unbalanced at frequencies f2 and f3 and electromotive forces at these frequencies will be induced in the secondary winding ll. Currents of frequencies f2 and f3 will accordingly be supplied through the corresponding frequency selective circuits IE to energize the two quick acting relays F2 and F3, which, with the third relay Fl deenergized, may be arranged in a suitable manner as hereinafter described to cause a G aspect to be indicated on the cab signal indication device. 7 to indicate to the engineman that he has passed a wayside signal showing a green aspect. Similarly, when the wayside signal displays a YY aspect the track inductor l is tuned to frequency f2 and the secondary winding ll of the receiver 5 supplies current of frequency fl and f3 to energize the two quick acting relays Fl and F3 to cause a YY indication to be displayed by device 1. A Y aspect will, as is evident, be obtained in a similar manner by the energization of relays Fl and F2 when receiver 5 passes over an inductor l tuned to frequency f3, whereas if the track inductor winding is open circuited, consequent upon the display of a stop aspect R. by the wayside signal, the cab signal inductor will become unbalanced to all frequencies and each of the quick acting relays Fl, F2 and F3 will become energized. The prior operation of the train stop receiver 6, in a manner to be described later, will have momentarily released a quick acting relay FIA under these circumstances to disconnect the cab signal circuits. In this way, an incorrect cab signal will not be displayed should one of the cab signal quick acting relays fail to become energized or, having become energized, if it should release to close its back contacts prior to the other cab signal quick acting relays releasing to open their front contacts. If desired, the quick acting relays Fl, F2, F3 and FlA may be used to operate a gong or other audible signal instead of or in addition to the visualindication of the signal aspects.

The train-stop receiver 6 is of the normally active type and comprises a magnetizable core on which are wound one or more primary windings l5 supplied with currents at frequencies fl, f2 and f3 through resonant circuits Hi from a suitable source of supply which may be the same source as that which is used to supply the cab signal inductor. The core of the receiver 6 is provided with extended pole faces separated by an air gap, like the receiver 5, by means of which the winding I5 is inductively coupled with Winding 2 when the receiver is in alignment with a wayside inductor so as to maintain the reluctance of its air gap with respect to flux of the resonant frequency. A portion of the flux due to winding l5 passes through a secondary core located in the air gap, upon which is wound a secondary winding l! which normally supplies current of frequencies fl, f2 and f3 induced therein by flux from the primary winding l5 through frequency selective circuits l8 and rectifier l9 to energize a quick acting relay F, and in addition supplies current of frequency fl through the frequency selective circuit 23 and rectifier 2l to energize the relay FlA. The frequency selective circuits l8 and 23 are so arranged that relay F is energized when and only when sufiicient current of one or another of the frequencies fl, f2 or f3 is supplied from the secondary winding l1, and relay FlA is energized when and only when suflicient current of frequency fl is supplied from winding ll.

The train-stop receiver 6 and track inductor l are so proportioned and arranged that when the one passes over the other the secondary winding i! will continue to supply enough current to winding H to maintain relay F or Fl A energized,

A only when the winding of the track inductor is tuned to a frequency to which the relay is responsive. When the receiver 6 comes into alignment with an inductor l tuned to frequency f2, for example, current of that frequency builds up in coil 2 to its resonant value to produce an opposing magnetomotive force which prevents a reduction of the flux of the same frequency in the core of winding I! and consequently relay F will continue to receive sufficient current to remain energized. The fluxes of frequencies fl and f3 however will pass freely through the core of inductor l and consequently the fluxes of these frequencies in the core of winding ll will be diverted or shunted, the reduction in the flux of frequency fl in the core of winding I! being sufficient to cause relay FlA to release. Relay FIA however will pick up again as soon as the receiver 6 has passed the inductor l. Similarly, relay F will remain energized and relay FlA release momentarily when receiver 6 passes a wayside inductor tuned to frequency f3, while in passing one tuned to frequency f l, both relays F and FlA will remain energized. It will thus be seen that, as relay F is arranged to be energized by currents of frequencies fl, f2 or f3, this relay will remain energized whenever the train-stop receiver passes over a track inductor the wayside signal associated with which is showing one of the proceed aspects. Should, however, the way side signal be displaying a stop aspect the track inductor winding 2 will be open circuited and secondary winding l! of the train-stop inductor will accordingly cease to supply current at any of the three frequencies and relay F will accordingly become de-energized and will release momentarily. The release of this relay may be utilized to cause an application of the brakes by releasing a stick relay MR controlling a normally energized magnet valve MV, as shown or by any other suitable means.

The circuits controlled by the three quick acting relays which are operated by the cabsignal receiver are so arranged that any signal indication given is held until the next signal location is passed. As shown in the drawing, this is achieved by arranging the three quick acting relays concerned to act in combination to control three signal indication stick relays GR, YYR and YR by which the lamps of the cab signal I are selectively lighted. Each signal indication relay is provided with a stick circuit which includes an energized contact a of an additional relay FlA controlled by output from the secondary windingof the train-stop receiver 6. The energizing circuit-for relay Fl A includes a frequency selective circuit 20 which passes current of frequency fl only and a rectifier 2|. The result will be that when the train stop receiver passes over a track inductor tuned to any frequency other than frequency fl, as would be the case if the associated signal were displaying any aspect other than green, relay FlA will release and break the stick circuit for that one of the signal indication relays which was energized on passing the previous signal location.

Considering now the mode of operation of the apparatus of our invention, it will be assumed that section IT in Fig. 2 is occupied by a train Vl so that the signals in the rear display the aspects indicated in the drawing and that a second train V2 equipped with the apparatus of Fig. 1 is approaching in section 5T. It will also be assumed that relays F and FlA are energized, and that the engineman has operated a reset key 22 to complete a circuit from one terminal B of a suitable source of current through relay MR to the other terminal C of the same source, and that relay MR has picked up to complete a stick circuit at its contact a extending to terminal 13 over contact a of relay F. The magnet valve MV, the release of which applies the brakes by suitable well-known means is held energized over contact 17 of relay MR.

When train V2 passes the inductor at the entrance to section 4T, since the adjacent signal is displaying its green aspect, contact 4 is in the position shown, tuning the inductor l to the frequency fl. As receiver 6 passes over inductor l, the currents of frequencies f2 and f3 supplied to relay F drop momentarily to a low value but 6 relay F and likewise relay FlA are held energized by current of frequency fl. Immediately thereafter, receiver 5 passes over inductor l and relays F2 and F3 are momentarily energized to complete a circuit from terminal B at contact 0 of relay MR over contacts a. of relays FIA, Fl, F2 and F3 through relay GR to terminal C, and relay GR picks up to complete a stick circuit at its contact a by which it is held energized while the train is in section AT. The operation of contact b of relay GR extinguishes lamp R and lights lamp G of the cab signaling device I. The gong It sounds at this time, due to the momentary closing of contacts d of relays F2 and F3.

It will be evident that if the. train entered section 51 with relay GR already energized to passing the preceding signal at green, the only effect would be a single stroke of the gong l4.

When receiver ii passes over the inductor at the entrance to section 3T, which is tuned to the frequency f2, the currents of frequencies fl and f3 supplied by coil I! drop momentarily to a low value, releasing relay FlA, which by opening its contact a releases relay GR and by closing its contact 1) causes gong id to sound. When receiver 5 passes over this inductor, relays F! and F3 pick up momentarily, completing a; circuit at their contacts I) to pick up the stick relay YYR, and by closing their contacts 01 causing gong l4 to sound a second time. Lamp G of the device 1 is now extinguished and the lamps Y, Y lighted over the front contacts I) and c of relay YYR, this indication being maintained until the train arrives at the next inductor location.

When receiver ii passes over the inductor at the entrance to section 2T, which is tuned to the frequency f3, relay WA is released in a similar manner, releasing relay YYR, and when receiver 5 passes over this inductor, relays Fl and F2 are momentarily energized to pick up relay YR to maintain onl the lower lamp Y lighted. Gong It is caused to sound twice at this location, as in the preceding example.

If now the train should pass the deenergized inductor at the entrance to the occupied section lT, relay F as well as relay FlA would be released by the operation of receiver ii, releasing relay YR to extinguish lamp Y and to light lamp R of device l, and relay MR would be released to deenergize magnet MV to apply the train brakes, unless the engineman operates the reset device 22. Upon the passage of receiver 5 over the inductor at this location relays Fl, F2 and F3 are energized to sound the gong l4, but without operating any of the cab signal indication relays.

It will be seen that the gong M is sounded once at each green signal and is sounded twice at each restrictive signal location.

It will be appreciated that, although in the foregoing example reference has been made to wayside signals, the invention may equally well be applied to an installation wherein actuated wayside signals are dispensed with. In this and in other respects various changes and modifications of the apparatus may be made within the scope of the appended claims without departing from the spirit and scope of the invention.

Having thus described our invention, what we claim is:

1. An intermittent inductive train control system comprising a trackway inductor having a winding on a magnetizable core, wayside means for tuning the circuit of said inductor at times to one or another of a plurality of frequencies,

a; first and a second train carried receiver, each having primary and secondary windings on magnetizable cores arranged to pass successively over said inductor, means supplying alternating currents of said plurality of frequenices continuously to said primary windings, a plurality of relays controllable through tuned circuits by currents induced in said secondary windings by the currents in said primary windings, the cores carrying said secondary windings being so disposed that a substantial change in the current of each frequency supplied thereto occurs when the respective receivers pass over said inductor but only if the circuit for the inductor winding is open or is tuned to a different frequency, the relays connected to the secondary winding of the first receiver being norm-ally energized and adapted to be selectively released upon passing said inductor and those controlled by the second receiver being energizable selectively only when passing said inductor, a plurality of signal indication relays having pick-up and stick circuits, means comprising a front contact of a relay controlled by the first receiver for opening said stick circuits, means comprising contacts of the relays controlled by the second receiver for selectively closing said pick up circuits, and a cab signaling device controlled by said stick relays.

2. An intermittent inductive train control system comprising a trackway inductor having a winding on a magnetizable core, a normally open circuit for said winding, means for completing said circuit at times through selective circuit elements tuned to one or another of a plurality of frequencies, a first and a second train carried receiver each having primary and secondary windings on magnetizable cores arranged to pass successively over said inductor, means supplying alternating currents of said plurality of frequencies to said primary windings, the secondary winding of said first receiver being so disposed that currents of said plurality of frequencies are normally induced therein and the current of each frequency is reduced substantially when the receiver is over a trackway inductor unless the inductor winding is tuned to the same frequency,

the secondary winding of the second receiver being so disposed that current of each frequency is effectively induced therein only when such receiver is over an inductor the winding of which is not tuned to the corresponding frequency, a plurality of relays connected to said secondary windings through selective circuit elements tuned to said different frequencies, those controlled by the first receiver being normally energized and those controlled by the second receiver being normally deenergized, a plurality of signal indication relays having stick circuits controlled by said normally energized relays and pick up circuits controlled by said normally deenergized relays, and a cab signaling device controlled by said signal indication relays.

3. An intermittent inductive train control system comprising a trackway inductor having a winding on a magnetizable core, a first and a second train carried receiver having primary and secondary windings on magnetizable cores arranged to pass successively over said inductor, means supplying alternating currents of a plurality of frequencies continuously to said primary windings, a plurality of relays controllable through tuned circuits to respond selectively to currents induced in said secondary windings by the currents in said primary windings, the secondary winding of the first receiver being on a core magnetically unbalanced with respect to its primary winding so that the relays controlled thereby are energized at all times except when the receiver is over said inductor, the secondary winding of the second receiver being balanced so that the relays controlled thereby are energized only when the receiver is over said inductor, condensers for tuning the circuit for said inductor winding at times to any of said frequencies to prevent an substantial change in the supply of energy of the corresponding frequency only, to the secondary winding of either receiver upon passing over said inductor, wayside means effective under restrictive trafiic conditions for opening the circuit for said inductor winding and under different proceed traffic conditions for completing said circuit through one or another of said condensers to render said circuit responsive to different frequencies, a plurality of stick relays controlled by said receiver-controlled relays having stick circuits arranged to be opened thereby when the first receiver passes over said inductor and pick-up circuits closed selectively thereby when the second receiver passes over said inductor, and a cab signaling device reflecting said traffic conditions controlled by said stick relays.

i. In combination, a train carried receiver including inductively coupled primary and secondary windings, means for energizing said primary winding by alternating currents of at least two frequencies, two relays normally energized by current induced in said secondary winding, the circuit for one relay including tuned circuit elements rendering such relay selectively responsive to current of one of said frequencies only and that for the other relay including tuned circuit elements which render it responsive to currents of each of said frequencies, a trackway inductor cooperating with said receiver comprising a winding on a magnetizable core, and acting to decrease the current of any frequency supplied to the secondary winding when the receiver passes over said inductor unless said inductor winding is included in a closed circuit tuned to a corresponding frequency, and wayside means for selectively tuning the circuit for said inductor Winding to one or another of said frequencies or for opening said circuit to effect the release of one or both of said relays or for maintaining both relays energized when the receiver passes over the inductor.

5. In combination, a train carried receiver including inductively coupled primary and secondary windings, means for energizing said primary winding by alternating currents of at least two frequencies, two relays normally energized by current induced in said secondary winding, the circuit for one relay including tuned circuit elements rendering such relay selectively responsive to current of one of said frequencies only and that for the other relay including tuned circuit elements which render it responsive to currents of each of said frequencies, a trackway inductor cooperating with said receiver comprising a winding on a magnetizable core, and acting to decrease the current of any frequency supplied to the secondary winding when the receiver passes over said inductor unless said inductor winding is included in a closed circuit tuned to a corresponding frequency, and wayside means which in one condition opens the circuit for said inductor winding to effect the release of both said relays, in a second condition closes the circuit for said winding through circuit elements tuned to one of said frequencies to release one of said relays while maintaining the other relay energized, and in a third condition closes said circuit through circuit elements tuned to another of said frequencies to maintain both relays energized while passing said. inductor.

6. In combination, a train carried receiver including inductively coupled primary and secondary windings, means normally supplying alternating currents of two frequencies to said primary winding, two relays normally energized by current induced in said secondary winding, the circuits for said relays including tuned circuit elements rendering one relay selectively responsive to current of one of said frequencies and the other relay responsive to current of either frequency, a trackway inductor having a winding and adapted to cooperate with said primary winding to materially reduce the current of either frequency in said secondary winding unless the inductor winding is tuned to the same frequency, and wayside means which in one condition opens the circuit for said inductor winding to effect the release of both of said relays, in another condition completes the circuit for said inductor winding through circuit elements tuned to one of said frequencies to prevent the release of either relay, and in a third condition completes said circuit through circuit elements tuned to the other of said frequencies to effect the release of only one of said relays when the receiver passes over said inductor.

7. In combination, a train carried receiver including inductively coupled primary and secondary windings, means normally supplying currents of two frequencies to said primary winding, train controlling apparatus governed by current delivered to said secondary winding and adapted to indicate one condition upon a reduction in said currents of two frequencies, to indicate a second condition upon a reduction in the current of one frequency only and to indicate a third condition upon a reduction in the current of the other frequency only, in said secondary winding, a wayside inductor having a winding inductively coupled to said primary winding when the receiver is adjacent the inductor, said inductor winding when deenergized being effective to reduce the current delivered by the primary winding to said secondary winding to establish said one condition, wayside means acting in one condition to open the circuit for said inductor winding and in other positions to complete said circuit through circuit elements tuned to one or the other of said frequencies to efiect the energization of said inductor winding by current induced therein by the current of the corresponding frequency in said primary winding, and means including the current in said inductor winding for preventing a reduction in the current of the corresponding frequency only delivered to said secondary winding whereby said second or third condition of said apparatus is indicated depending upon the condition of said wayside means.

8. In combination, a train carried receiver inluding a primary winding normally supplied with alternating currents of a plurality of frequencies and a secondary winding having a magnetic circuit balanced with respect to said primary winding so that normally substantially no current is induced therein, a trackway inductor adapted to unbalance said magnetic circuit to cause currents to be induced in the secondary winding by the currents in the primary winding when the receiver is adjacent the inductor, a

wayside circuit including a winding on said inductor, means for tuning said wayside circuit to cause current of any one of said frequencies to be induced in said inductor winding by current in said primary winding, means including the current induced in said inductor winding for maintaining the magnetic balance of said receiver to prevent the energization of that one of said relays which is tuned to the corresponding frequency, and train governing means controlled jointly by said frequency responsive relays.

9. In combination with a stretch of railway track divided into block sections, a plurality of trackway inductors comprising magnetizable cores with windings thereon, each of which is adjacent the track rails in a different block section, a traincarried receiver comprising a primary winding normally supplied with alternating cur rents of a plurality of frequencies and mounted on a magnetizable core, a secondary winding on said receiver mounted on a core which is magnetically balanced so that substantially no current is induced therein by said primary winding except when its core is over the core of a trackway inductor, a plurality of relays connected to said secondary windings through tuned circuit elements by which each is rendered responsive to current of a different one of said frequencies supplied to said secondary winding, and means for tuning said inductor winding to a selected one of said frequencies to induce current therein of a corresponding frequency, and means includ-- ing said induced current for maintaining the balance of said secondary winding with respect to said selected frequency to cause only the relays tuned to the other frequencies of said plurality to operate upon the passage of the receiver over a trackway inductor.

10. In a train control system, a train carried receiver including a primary and a secondary winding, a plurality of frequency responsive relays, each responsive to a different frequency, a tuned circuit for each relay including said secondary winding over which each such relay is energized only when the secondary winding is supplied with alternating current of a corresponding frequency, a source of current of each such frequency connected to said primary winding through a tuned circuit to supply current of a corresponding frequency thereto, a trackway inductor comprising a magnetizable core coopcrating with said primary winding to govern the current supplied to said secondary winding, and means comprising a winding on said inductor core and a circuit for said winding adapted to be tuned to any one of said frequencies for selectively controlling the operation of said relays.

11. In a train control system, a trackway inductor having a winding, a first and a second train carried receiver arranged to pass successively over said inductor each having a primary and a secondary winding, means for supplying alternating currents of a plurality of frequencies to said primary windings, a plurality of wayside circuits including said inductor winding, each tuned to a diiferent one of said frequencies and adapted to be inductively'energized by the current of corresponding frequency in said primary windings as the receivers pass over the inductor, means comprising the current of each frequency in the primary windings of said receivers for inducing current of the corresponding frequency in the associated secondary windings subject to control by current of the same frequency induced in said inductor winding, a plurality of signal indication stick relays having pick up and stick circuits, means selectively controlled in accordance with the frequency of the current supplied to the secondary windings of said receivers for opening said stick circuits when the first receiver passes over said inductor, means for closing the pick-up circuit for a selected one of said signal indication relays when the second receiver passes over said inductor, whereby a selected one of said relays becomes energized to complete its stick circuit, and a cab signaling device controlled jointly by said signal indication stick relays.

12. In a train control system, a trackway inductor having a winding, a first and a second train carried receiver arranged to pass successively over said inductor, each having a normally energized primary winding adapted to supply energy to said inductor winding and to also supply energy at times to the associated secondary winding subject to control in accordance with the condition of energization of said inductor winding, wayside means for controlling the energization of said inductor winding by said primary windings to establish one condition of energization under proceed traffic conditions, another under restrictive conditions and to prevent the energization of said inductor winding under stop traffic conditions, a plurality of stick relays having pick up and stick circuits, means controlled by the energy supplied to the secondary winding of the first receiver for opening the stick circuits for said relays upon passing said inductor under restrictive or stop conditions, means controlled by the energy supplied to the secondary winding of the second receiver for closing the pick-up circuit for one or another of said stick relays to effect its energization and thereby establish its stick circuit upon passing said inductor under proceed or restrictive conditions, respectively, and a cab signaling device for indicating said traffic conditions controlled by said stick relays.

13. In a train control system, a trackway inductor having a winding, a train carried train stop receiver and a cab signal receiver arranged to pass successively over said inductor, a primary Winding and a secondary winding on each receiver, each primary winding being normally energized by alternating currents of at least two different frequencies and adapted to energize said inductor winding upon passage of the receiver over an inductor, each primary winding cooperating with such inductor winding to jointly control the energization of the associated secondary winding, wayside means for conditioning each inductor winding for energization by current of one frequency or another in accordance with different proceed trailic conditions and for maintaining such inductor winding deenergized under stop traffic conditions in said stretch, a first frequency responsive relay, a circuit including the secondary winding of said train stop receiver effective to maintain said first relay energized at all times except when passing over an inductor which is not energized by current of the frequency to which said first relay is responsive, a plurality of normally deenergized relays, each responsive to a different one of said frequencies, means including the secondary winding of said cab signal receiver for momentarily energizing each relay of said plurality upon passing over said inductor when the inductor winding is deenergized and acting when said winding is energized by current of any one of said frequencies for energizing all of the relays of said plurality except the one tuned to that particular frequency, a cab signaling device, means for releasing said device upon the energization of said first relay and means responsive to the energization of all but one of the relays of said plurality for causing said device to indicate different proceed traffic conditions depending upon which of said relays is not energized.

14. In combination with a stretch of railway track divided into blocks, a normally inert trackway inductor for each block having a winding, means including resonant circuit elements for conditioning each inductor winding for selective energization by currents of different frequencies in accordance with proceed or restrictive trafiic conditions and for opening the circuit for such winding under stop conditions, means carried by a train traversing said stretch for energizing said inductor windings comprising a train stop receiver and a cab signal receiver arranged to pass successively over each inductor, each such receiver having a primary winding normally energized by current of each of the frequencies to which such inductors are responsive, a cab signaling device and a train stop device on said train, a secondary winding on each receiver adapted to assume different distinctive conditions of energization when such receiver is passing over a trackway inductor corresponding to the condition of energization of said inductor, means controlled in accordance with the condition of the secondary winding of said train stop receiver for actuating said train stop device and for causing a stop indication to be displayed by said cab signaling device upon passing a deenergized inductor, and means controlled in accordance with the condition of energization of the secondary winding of said cab signal receiver for indicating trailic conditions as refiected by the condition of said inductor winding.

15. In combination with a stretch of railway track divided into blocks, a normally inert trackway inductor for each block having a winding, means including resonant circuit elements for conditioning each inductor winding for selective energization by currents of diiferent frequencies in accordance with proceed or restrictive traffic conditions and for opening the circuit for such winding under stop conditions, means carried by a train traversing said stretch for energizing said inductor windings comprising a train stop receiver and a cab signal receiver arranged to pass successively over each inductor, each such receiver having a primary winding normally energized by current of each of the frequencies to which such inductors are responsive, a visual cab signaling device and an audible warning signal on said train, a secondary winding on each receiver adapted to assume different distinctive conditions of energization when such receiver is passing over a trackway inductor corresponding to the condition of energization of said inductor, means controlled in accordance with the condition of the secondary winding of said train stop receiver for causing said warning signal to sound and said cab signaling device to display a stop indication when passing a deenergized inductor or when passing an inductor energized to indicate restrictive traflic conditions,

and means controlled in accordance with the condition of the secondary winding of said cab signal receiver for causing said warning signal to sound upon passing each wayside inductor regardless of its energized or deenergized condition, and in the event such inductor is energized to indicate proceed or restrictive traffic conditions, said means acting to cause the cab signaling device to change its indication from stop to a corresponding proceed or restrictive indication.

16. In combination with a stretch of railway track divided into blocks, a train control system for governing traffic movements over said stretch comprising a normally inert trackway inductor for each block, means on a train traversing said stretch for supplying energy successively to said inductors, comprising a receiver having a primary winding supplied with alternating current of a plurality of frequencies, a winding on each trackway inductor arranged to receive energy from said primary winding when the train passes over such inductor, wayside circuit controlling means for each inductor for conditioning its winding for selective energization under different proceed or restrictive trafilc conditions by currents of correspondingly different frequencies induced therein by energy received from said primary winding, and for maintaining the inductor winding deenergized under stop condh tions, means comprising a secondary winding on said receiver effective when passing a trackway inductor for detecting the condition of the inductor Winding, a plurality of normally deenergized relays, a circuit for each relay including frequency responsive elements so arranged that each relay is responsive to a different one of the frequencies supplied to said primary winding, means including said secondary winding for momentarily energizing each of said relays upon passing over an inductor the winding of which is deenergized, said means being effective when such inductor winding is energized by current of any one of said frequencies to energize all of said relays except the one tuned to the same frequency, a cab signaling device adapted to display different signal aspects, and a plurality of circuits for controlling the aspect displayed by said device, each such circuit including a back contact of a different one of said relays and a front contact of each of the other relays in series therewith.

17. In combination with a stretch of railway track divided into blocks, control means for indicating traffic conditions in said blocks, a single normally inert trackway inductor for each block, a winding on each inductor, means including resonant circuit elements selected by said control means for conditioning each inductor winding for selective energization by currents of different frequencies in accordance with proceed or restrictive traffic conditions and for opening the circuit for such winding under stop conditions, means carried by a train traversing said stretch for supplying energy of each of said frequencies to said inductors as they are passed over by said train, receiving means on said train comprising two receiver windings arranged to cooperate successively with the winding of each inductor, a cab signaling devic on said train, means controlled by the first receiver winding for causing a stop indication to be displayed by said device on passing a deenergized inductor, and means controlled jointly by the first and second receiver windings for causing proceed or restrictive indications to be displayed by said device in accordance with the frequency of energization of an energized inductor passed by said train.

18. In combination, a transformer having primary and secondary windings on magnetic cores separated by air gaps, energy sources for constantly supp ying alternating currents of a plurality of selected frequencies to said primary winding, a plurality of relays, a circuit for each relay including said secondary winding and resonant circuit elements for selectively energizing different relays by currents of the different frequenci s supplied by said secondary winding, a magnetic shunt effective when bridged across at least one of said air gaps to vary the energy supplied to said relays by said secondary winding by an amount sufficient to effect their control, a winding on said magnetic shunt which renders it ineffective at a particular frequency only when said winding is included in a closed circuit tuned to the corresponding frequency, and means for closing the circuit for said winding and tuning it at times to one of said frequencies and at other times to another of said frequencies to effect the selective control of said relays.

19. In combination, a transformer having primary and secondary windings on magnetic cores separated by four air gaps which form the arms of a magnetic bridge, two of said arms being between one end of the primary core and the opposite ends of the secondary core, the other two arms being between said opposite ends of the secondary core and the other end of the primary core, energy sources for constantly supplying alternating currents of a plurality of selected frequencies to said secondary winding, a plurality of relays, a circuit for each relay including said secondary winding and resonant circuit elements for selectively energizing different relays by currents of the different frequencies supplied by said secondary winding, a magnetic shunt effective when bridged across one of said air gaps to cause a substantial change in the energy of each of said frequencies supplied by the secondary winding to said relays due to the resulting change in the ratio of said bridge arms, a winding on said magnetic shunt which renders it ineffective at a particular frequency only when said winding is included in a closed circuit tuned to the corresponding frequency, and means for closing the circuit for said winding and tuning it at different times to each of said frequencies to effect the selective control of said relays.

LESLIE HURST PETER. DOUGLAS GOLDIE SHIPP.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Germany "55pm 22, 1921

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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2673292 *Jul 16, 1949Mar 23, 1954Westinghouse Air Brake CoVehicle reporting system
US2693525 *Jan 17, 1951Nov 2, 1954Gen Railway Signal CoInductive control system
US2768286 *Dec 13, 1951Oct 23, 1956Gen Railway Signal CoInductive train brake control system
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Classifications
U.S. Classification246/63.00R, 246/28.00R, 246/194
International ClassificationB61L3/12, B61L3/00
Cooperative ClassificationB61L3/121
European ClassificationB61L3/12A