US2393135A

US2393135A - Railway track circuit apparatus

Info

Publication number: US2393135A
Application number: US426055A
Authority: US
Inventors: Norman F Agnew
Original assignee: Union Switch and Signal Inc
Current assignee: Hitachi Rail STS USA Inc
Priority date: 1942-01-08
Filing date: 1942-01-08
Publication date: 1946-01-15
Anticipated expiration: 1963-01-15

Description

Jan. l5, 1946. l N. F. AGNEW 2,393,135

RAILWAY TRACKl CIRCUIT APPARATUS A V Filed Jan. J8, 1942 SE Zi HISTTaRMI: y

l1 14 @/15 9 V9 l Accordingto the invention, a railway track circuit of the impulse type is provided with a reverse circuit arranged to be eiective to exert a control in advance of a, train on the section. This reverse circuit may be utilized forA controlling any desired function such as the illumination of signal lamps upon approach of a train to a signal,

or the operation of a highway crossing signal at a railway-highway intersection, etc. In one embodiment of my invention, represented in Fig, 1, the reverse circuit is employed to eiiect approach lighting of signals and is applied `to a stretch of single track railroad over which trac operates in the direction indicated by an arrow or from right to left as viewed in the drawing, The track rails I and la are divided by insulated joints 2 into a plurality of successive adjoining track sections, of which only one section, D---E, is shown complete in the drawing. Section D-E is provided with an impulse type track circuit of the class illustrated and described in detail in the aforesaid Patent No. 2,173,806,4 and which track circuit has incorporated therein means for additionally providing the section with a second or reverse track circuit. These track rcircuit means include impulse transmitting means at one end of the section and impulse translating means at the opposite end of the section.

The impulse transmitting means, as shown, comprise a track transformer TT having a primary winding 4 periodically supplied with unidirectional current from any suitable source, such as fromk a battery not shown but having its opposite terminals designated by the reference characters B and. C, each time a contact 5-6 operated by a contact operating device CT is closed. The device CT may be, for example, a code transmitter which is arranged to operate its contacts 5-6 at a selected rate of, say, 60 times per minute. Primary winding 4 of transformer 'IT has connected in multiple therewith a condenser I arranged to control the time constant of the circuit so as to cause the current in the winding to build up gradually and' reach its steady state value at substantially the end of eachfinterval that contact 5-6 is clo'sed. This energyV in winding 4 creates a iiux which collapses or decays rapidly each time contact 5 6 opens, and this Yrapid-collapse of iiuX induces a Voltage impulse of relatively large magnitude-in secondary winding 8 of transformer TT.v -Winding 8 is connected in series with the operatingwinding of a relay, designated by the reference character AR with a suitably distinguishing suffix, across the track rails I and la at the exit end of section D-E, and preferably, there is connected in multiple with thewinding of relay ARD an asymmetric unit 9 poled in a direction to be made clear presently so as to shunt currentof a given relative polarity away from relay ARD.

The impulse translating means at'the opposite or entrance end of section D-E comprises a winding I provided with contact means operated thereby, and a source of unidirectional cur-- rent such as a battery II, connected in series across the trackrails I and-Ia at the entrance end of section D-E. Winding I0 preferably has connected in series 'therewith an asymmetric unit I2 poled in opposition to the flow of current from battery Il, and connected in multiple ywith winding IIJ and unit I2 is a resistor I3 and an asymmetric unit I4 poled to permit the flow of current from the battery.

The winding Ill represened in Fig. l'comprises the operating winding of a relay, designated by the reference character TR with a suitably disa tingushing suffix, and preferably of the biased polar neutral type. Relay TRE has a contact member which is biased to a normal, or left-hand position as illustrated in the drawing, and which contact member is caused to operate to its other or right-hand position in response to energization of its operating winding by a voltage impulse of a given relative polarity. Operatively associated with contact I are signal control means, designated by the reference character I6. The details of such control means are not shown in the presentgcase, Ybut these means may be similar, for example, to the means shown in the aforesaid Patent No. 2,178,806, associated with the contacts of the imipulse operated track relay of the patent.

Associated with each section adjacent its entrance rend is a traflic controlling signal, designatedby the reference character S with a suitably'distinguishing sufx. Each signal S is selectively controlled by the impulse translating means of its associated section, in a manner indicated in the drawing but not shown since the details of such control are well known and form no part of the present invention. Each signal S is, however, normally inactive, that is, normally non-illuminated, and becomes illuminated to displayv an active indication or aspect only upon release-of the approach lighting relay AR incorporated into the track circuit apparatus of the section next inthe rear. Signal SD, for example, may be supplied with illuminating or activating `energy when and only when back contact I8 'of relay ARD, associated with section D-E in the rear of signal SD, is closed to complete an obvious circuit for lamp L of the signal.

[The apparatus represented in Fig. 1 is in its normal condition, as represented in the drawing, when section D-E and the adjacent rear and advance sections are unoccupied. In this condition of ,the apparatus, relay ARD of section D-E is held up by energy supplied over a circuit which extends from 'one terminal of battery II through asymmetrical unit I4 in its low resistance direction, resistor I3, rail la, winding 8 of transformer TT, the winding of relay ARD, rail I, and the other terminal of battery I I. This energy is blocked frompassing through track relay TRE duelto asymmetrical unit I2 which presents its high resistance direction to the flow of energy from the battery. Relay ARD accordingly is held picked up by energy from battery II, lbut this energy has no effect or inuence on track relay TRE; Track relay TRE responds, however, to relatively Vhigh peakvoltage'impulses caused to be transmitted from Vwinding 8 due to the periodic energization of its inductively coupled winding 4. Thaty is toY say, each time contact 5-6 of coder CT closes, Yunidirectional energy is supplied to winding #and slowly builds up to its steady state value. At such time, there is relatively little if anyY inductive transfer of energy to winding Y 8, due tothe relatively slow rate of change of flua'inA the transformer. When, however, contact 5-6 opens, the ilux in the transformer rapidly collapses and the parts of the transformer are so arranged to cause a relatively high impulse having a given relative polarity, indicatedA in the drawing by the reference marks v-land to be inducedin winding 8. This impulse is transmitted to relay TRE over a circuit which extends from one terminal of transformer TT metrical unit I2 in its low resistance direction,

aaaaiac. battery. Il in opposition to its electromotive force.,`

rait l; and asymmetrical vunit 9 in.' itskv low resiste.

ance. direction. to the other terminal. of winding.

8: "Each voltage. impulse. is thus; shunted: away from approach lighting. relay ARD. dueto the low resistance'path of asymmetrical; unit 9, hence.-

of the. proper relative polarity to.' cause track` ree lay TRE to operate its contactmembers, hence.

the' signal control means'zassociated. 'therewith are-.normally conditioned. to cause the associated;

signalsSE. to indicate that' section `D.E 'is unoccupied` Signal SEis, however, inactivev orl deenergized. sincey the. energizing circuits thereof are deenergized due t'o. backy contact lli vof relayiARE beingopened.

'When'. a train occupies thesection in the-rear of` section DE, relay ARE is caused to release and` close its back contact I3 to render signal SE activek and. capableL of displayingV an illuminated indication. Both relays TREf and.: ARDy are shuntedwhen the train enters section` D-E, hence` signal SD becomes approach` lighted while the'signal control apparatus associated withsignal-SE'conditions that signal todisplay its block occupied indication. After the train-vacates the section in the `rear ofsection relay ARE picks vup to deenergizel signal SE, andl afterrthe train` vacates section D-E, both relays ARD and TRE'become energized andthe track circuit appar-atusofi section D-E is restored 'to itsnormal condition; as represented in the drawing.

Theimpulsetrack-circuitsfrepresented inlig 1 are"norm'ally energized, `as is the customary practice. Under certain conditions, itmay bedesiravble to arrange the Vcircuits to- Yloe normallydeenergized, vand provide meansnranliallycon-l trollable for energizing the .circuits-s as desired.

The apparatus illustrated in Fig. 2 representsonearrangement, whereby normally deenergizedl trackfcircuits ofthe impulse typemay-b'eF-energizedatvvill-A by manually operable means. Re-

ferring to Fig. 2, the reference character LHSR designates a signal" control relay manuallyY con` trollable from a remote: point in anysuitablemanrier, as by means of a communication orc'entifalized trame control system such as--isshown,

forfexainpie, in the Lewis PatentNq. aim-130,4

grantejifApril 16, 1940, for Remote control apparatus, 'For the purposes 'of thel present descriptinitis deemed suiii'cient to state thathrelay LHS-R, is `normally released, andY that its front-5 centlactL 2 1 is normally opened to disconnect terfrom primary winding Il of transformer Under such conditions, no energy isappliedto transfermer.'IIY eventhough contacts 5 and 22- ofr'coder CT may 'bei intermittently closed andl Opened? hence r1.0' voltage impulses "ae @assedio be transmitted from secondaryv winding 8and=as a result the tr'ackrelay TRis causedto retain tion'. l'Relay' TR may be directly interposed in' wir miter'y'- Il; tonie raiis'l and la. in this leiter case.' battery.. il feeds Current" through windingl'llof transformerRT; butithis currerit has. littleJ if. any,y effect.'` upon relay.y TRE, since it is unidirectionalin character Aand. hence. does.- not cause aninductivetransfer oenergyfto the.relayi.vv The. arrangement, mayalso involve 'additional checking apparatus. comprising` a. checking relay?.

CR andi atime. elementv relay- TE, shown for.. example infFig. 2 .associated with. relay TRE..

"Ihe impulseitrack circuits. illustrated, ini` Fig,

are. arranged. to eiect different controls :accord:--

ing tothe relativeepolarity ofthe voltage impulses appliedr'to the circuits. Thel track rel'aysem..

ployed inFig, 2 accordingly are offthetype having-y a`polar armature biased `to2 a center or midi posia". tion, andoperab'le to; either one or theother-ofg.y

twolextreme positions; according as tneoperating...

relayfwinding. is. energizedby current of .onar'ela-.

tive, polarity ori-the. other; Each track relayfhas.

associatedrtherewith signal control meanscomprising( twoA control: relays,v NC-and; PCi. but only;v

thei two. control .relays associated: with. relay;.TRlD-.y

arev illustrated; in the drawing. Relay.; NC. .isicon-A nectede through a A full-wave rectifier Zitto seconde.. ary winding. 25: ofsa. transformerfD'Itli, whilerelay,

PGJis .connected through another. rectiii'erA Zitto. secondary winding 25 of" another transformer DTZ?. TheI primary winding, Zoff transormer DTI. is.l suppliedv with unidirectional current each.A

time` armature lfof'relay. TRD- operates 1z0-its left-hand position (las viewed in Fig. 2) andihencel, relay NQ.. is` supplied: Withenergyyinductively/ transniittedl from.winding. 2.6 V.each timeI contact... 1510i relaylBRD is. caused tov assume its leftzfhandq.

positiony due to. theenergization otrsuchrelay by. voltage impulses having a` given.. relative polarity hereinafterv assumed to be of negative polarity; Similarly; the primary wind-ing Zzofrthe. other transformer. DTZ is` supplied..withY unidirectional?` energy eachv time contact I l'roiirelay-l 'IRDiscaused?.1

to operateto itsrightfhandipositicn in. response.: to energization 0f; the. relay. byV energy. off-the opposite or positive polarity. rEhe relays NC- and PC' are arranged to` be effectively energized andz picked up when supplied with energy` impulses:

from their associated;transformers atthe prede. termined-l code .rate hereinbefore assumedr to beY Gcyclesper minute, hence it` follows that, when. relay TRD responds to voltage impulses: ofnega.-

tivepolarity, relay- NC ispicke'dup; whenrelayv TRD; responds to .voltage impulses of' positive po?,

responds; alternatelyY to voltage impulses of rst..

negative andgthenpositive polarity, both relays.

NCand BC are pickedup.

Relays NCandi-.PC cooperate with relays-LHsRz, andARDin controlling the associated wayside When relayV ARDlis released; its hack contact lS-iis closed and;

signal SD, inthe'following manner.

energy is .then applied-to the signal control circuits. hereinafter described, thereby conditioning.I

the associated signal to display an. active` or. illu,- minatedl indication. When Vrelay ARD is-picked up, however, energy is removed from-.the signali control circuits and: asa `result the-asscciatedz When relay., LHSR. .isr.:

signal: isr dark.: or inactive. released, .theiproceed indication-.lamps or theassociated signalare placed on open circuit-and;` such lamps accordingly VVcannot-become; energized; to display an illuminatedf'or active indication.'- These lamps may, however, be. energizedif relayf `LI-lSRV is picked up to closeits front contact 28.. The in ost restrictive orl stop aspect of thewaylarity, relay PC ispicked up; and when relay TRDv SD toiterminal C. Signal SD accordingly is conditioned to display its stop aspect when both control relays NC and vPC are released. When relay NC is picked up and relay PC is released, the signal is then conditioned to display an approach indication, over a circuit which includes the lament of lamp 32, front contact 30 of relay NC and .back contact 28 of relay PC, and which cir cuitfis completed when front contact 28 of relay LHSR and back contactl of relay ARD are closed. When relay PC is picked up but relay NC is released, signal SD is then conditioned to display an approach restricting indication, over a circuit which includes front contact 28 of relay LHSR, the filament of lamp 33 of signal SD, back contact 35 of relay NC, front contact 29 of relay PC, and back contact I8 of relay ARD. Signal SD is conditioned to display its clear aspect when both relays NC and PC are picked up to prepare a circuit which includes back contact i8 of relay ARD, front contact 29 of relay PC, front contact 35 of relay NC, the filament of lamp 34 of signal SD, and front contact 28 of relay LHSR. The control relays NC and PC cooperate in controlling the polarity of voltage impulses impressed on the track circuit of the section next in the rear. As pointed out hereinbefore, impulse track circuit energy is removed from a section unless the remotely, controlled relay LHSR associated therewith is picked up to close its front contact 2l. When this happens, the section in the rear is supplied with voltage impulses of negative polarity when .both relays NC and PC of the section in advance are released; is supplied with voltage impulses of positive polarity if relay NC is picked up but relay PC is released; and is supplied with voltage impulses -of alternately negative and positive polarity if relay PC is picked up, or if both relays NC and PC are picked up.

Voltage impulses of negative polarity are caused to be transmitted from transformer TT to the rails of section D-E when relay LHSR is picked up and relays NC and PC are both released to complete a circuit extending from terminal B through iront contact 2| of relay LHSR, back contact 31 of relay NC, back contact 38 of relay PC, contact 3822 (when closed) of coder CT, primary winding 4 of transformer TT, and contact 5-49 (when closed) of coder CT. Each time contact members 5 and 22 oi coder CT engage their respective contact .points 40 and 39, unidirectional energy is supplied to winding' 4 and' traverses that winding in one direction to set up a ilux of a given direction, which flux collapses rapidly when the coder contacts open' and cause a voltage impulse of a given relative polarity (assumed to be negative polarity) 'to be transmitted from winding 8 to the track rails. When relays LHSR and NC are picked up, there is established a circuit extending from terminal B through front contact 2i of relay LHSR, front contact 31 of relay NC, hack contact 42 of relay PC,"contact 6 5 (when closed) of coder CT, winding 4, and contact 22-4i (when closed) of coder CT to terminal C. Each time the coder contacts 5 and 22 engage their respective lcontact i points 6 and 4I, unidirectional energy is caused to traverse Winding 4 in the direction opposite that of energy supplied When both vrelays NC and PC are released, hence iiux of the opposite direction is created in transformer TT, 'and each time the coder contacts open, avoltage impulse of the Opposite (or positivel` polarity isrcaused to be transmitted to thetrackrails. When relays ascencerelay NCand the filament oflamp 3l of signal LHSR and PC are both picked up, unidirectional energy is supplied to winding 4 iirst in one direction, over front contact 38 oi relay PC, when coder contacts 39--22 and 5--40 are closed, and thenin the other direction over front contact 42 of relay PC each time coder contacts 6--5 and 22-4! are closed. It follows, therefore, that Y whenever relay PC, or both relays NC and PC are associated section is or is not occupied. That is to say, relay ARD may be employed to cause the communication system to transmit an indication code to the oilice each time the relay operates from either position to the other. When relay ARD picks up,` its front contact 45 closes and this contact may condition the station equipment, in a well-known manner, to transmit to the cnice an'indication relating to an unoccupied section, and each time relay ARD releases, its back contact 45 closes and may condition the station equipment to transmit to theoiice an indication code relating to an occupied section.

The apparatus of Fig. 2 is in its normal condition, as represented in the drawing, when section D-E and the section in advance are unoccupied,

relay LHSR is released, and the impulse track circuit of the advance section is deenergized. IIn this condition. of the apparatus, relay ARD is held Venergized by current supplied from battery Il, but relay TRE is inactive since the impulse track circuit is deenergized. Under the conditions assumed, signal SD is conditioned to display its stop aspect, and will do so should a Westbound train enter the section to shunt relay ARD and cause its back contact I8 to complete the previously traced circuit for lamp 3i of signal SD.

The release of relay ARD at this time will cause an occupied section indication code to be transmitted to the oflice by the communication system. The operator will therefore be informedrof the presence of the train on section D-E, even 4though the impulse track circuits employed for governing the train movement are deenergized. Should the train vacate section D-E, relay ARD then will pick up and cause the communication system to transmit an unoccupied section code to .the oice to indicate that section D-E is vacant.

If, however, section D-E remains cleared, and the operator wishes to authorize a Westbound train to proceed over the stretch, he will suitably control the communication system to cause the signal control stick relays LHSR to pick up.,

When this happens, the signal control relays NC and PC associated with the section in advance of section D-E will be controlled according to the type oienergy causing operation of the associated track relay TRD. I shall assume that this energy is of the clear code type comprising voltage impulses of alternately positive and negative polarity. Under the assumed conditions, vboth relays NC and PC will be picked up; voltage impulses of alternately positive and negative polarity will be applied to the rails of section D-E; and signal SD will be conditioned to display its clear aspect. When a westbound train enters section D-E, and shunts current from battery H away from relay ARD, the signal will then display `:active Yor illuminated clear aspect.; and

@the communication system ywill "be conditioned 'to k.transrnit the occupied section indication code tothe oice.

fWhen the train :enters the section 1in :advance -ofise'ction -D-E, relay TRD is shunted andiboth control relays NC and EPC are released, thereby conditioning signal SD to display its illuminated stop aspect.' lAftervthe train vacates .section DfE,

voltage limpulses of .negative Lpolarity .are :im--

pressed onthe track vrails and cause response of V'the associated relay TRD. Relay ARD Salso picks Aup to remove :energy from the signal -c'ontrol'circuits, thereby causingssignal SD @to `.become dark;

land also to cause fthe communication system vto transmit to theoice the unoccupiedsectionlcode. When the section in advance -becomes vvacated and relay 'IRD `responds .to voltage impulses of negative polarity, relay NC picks up to cause the impulse transmitting apparatus of section YDlil to "supply impulses of positive polarity to the associated track rails, and Valso to condition signal SD `to `display .its approach aspect. Signal `SD is 'conditioned to display .its approach restricting aspect when relay :PC is picked up and relay NC is 'released due to relay TRD responding to voltage vimpulses of positive polarity applied to the section in advance of section D-E when the train vacates the second Asection in advance of sec- Y tion D-E, Withrelay PC picked up, the impulse transmitting apparatus or vsection D-E is caused to apply voltage impulses of alternately negative and ,positive polarity to the rails of the section.

When three or more .sections in advance of section D-E are unoccupied, relay TRD is caused to respond to voltage impulses of alternately positive and negative polarity, and both relays NC and PC associated therewith are picked upto condition signal SD to -display its clear aspect, and

, also to cause voltage impulses of alternately positive and negative polarity to be impressed on the rails of -section -D-E.

The apparatus of Fig. -2 may be restored to its normal condition by the operator causing a suitable control to be transmittedover the communication system to cause the signal control relay LHSR to be released. When this happens, energy is removed from the impulse track circuits whereupon the track relays 'I'R become inactive; the

associated control relays become released; and the associated signals S are conditioned to display their respective stop aspects should Aa train enter their associated sections under theconditions assumed.

The impulse translating arrange-ment involving track relay TRD of Fig. 2 might be subject to a false operation should a. loose connection of battery I I to the track rails exist. This loose connection, when vibrated as by the passage of a train, might cause an inductive transfer of energy from battery II to relayTRD, and thereby cause an .operation of the relay so as to give a false apand winding I0 across the rails I and la. Relay `(IRAS `:atljustedto `be normally energized regardless lof whether the :associated 'section Ais 4occupied or unoccupied, and releases `only Ain the -event -that the circuit col'mecti'on ofibatte'ry II tothe rails Ibecomes interrupted. When this happens, `relay CR opens its liront contact 48 and places battery -i'I --on open circuit, thereby lavoiding any possiibility that `a looseicbnnection `vibrated alternately open and closed might cause unauthorized response of relay When relay CR releases, a time 'element device TE, suchas a thermal relay, becomes Lenergized over an obvious circuit'including battery II, back contact 48 of relay CR, and operating element 49 of time element device at the end oi the predetermined time intervaflof the device, its'contact `li'll'closes to complete a circuit path including back contact 48 of relay CR `andcontactl) of device TE, which `path `coh- -nects relay -CR and battery H to the trackrails in -a pick-up circuit. Should the connection Vof relay CR and battery lI I tothe track rails `befopen due toa break in the circuit connection, relay CR jof course will remain :released to maintain device TE energized, until the break hasv been repaired. Should, however, the bro-ken connection be of the type 'that is intermittently vibrated open and closed, relay CR might pick upduring the interval that the circuit connection is vibra-ted closed, thereby deenergizing device TE, but after contact 50 of -the'device opens, relay CR will release during the interval that the circuit connection is vibrated open, and battery III again will be placed on open circuit, and device TE again will beenergized. This cycle of operation will be repeated as long as the yintermittently closed broken connection exists in the apparatus, but of course relay TRE will be aiected only momentarily if [at al1, lhence the relay will remain inactive anda display of a false proceed indication will beprevented.

From the foregoing description, it is readily apparent that I have provided novel and improved track circuit apparatus of the double track circuit type wherein one of the circuits is of the impulse type. Itis also apparent that I have provided means whereby traic on the stretch may be safely governed even though one of the track circuits is` normally deenergized and is manually controllable to authorize a train movementat the will'of an operator. In addition, it is apparent that the apparatus may be arranged to insure against a 4false voperation of the apparatus should a Jbroken connection exist in the impulse translating means.

Although I .have herein shown and described only a few forms of railway track circuit apparatus embodying my invention, it is understoodthat various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

l. In combination, a section of railway track, a first source of energy,l a first relay means having a rst winding connected in series with said rst source to the rails at one end of said section,V said first relay means having contacts biased to anormal position wherein theyare held when said rst winding is steadily energized by current from said first source but which contacts are operated away from said normal position when said rst winding is intermittently supplied with impulses of energy, and means for intermittently impressing energy on said track rails at the opposite `end of said section, said means comprising a second i windingand a second relay connected in series ',to'the rails at said opposite end of said section,

said second relay being so constructed as to be immune to impulses of energy from said Winding,

' asecond source of energy at said opposite end of saidlsection, contact means having ay contact periodically opened and closed, and another winding inductively coupled with said second windingand -supplied with energy from said second source when said contact is closed for4 creating flux effective each time said contact is opened for causingan' impulse of energy to be induced in said second Winding.

2. In combination, a section of railway track,

.a track transformer, a circuit for the primary winding of said transformer including a source of unidirectional energy and a contact periodically closed for periodically energizing said winding and eifective each time when opened for causingfthe induction of an impulse of current in the secondary winding of said transformer, a relay connected in series with said secondary'winding to the rails at one end of said section, said relay being so constructed as to be immune to impulses induced in said secondary winding, a second source of unidirectional energy for energizing :said relay, another winding connected in series with said second source to the rails at the opposite end of said section, and contacts operated by vmeans responsive to the energization ofv said other -closed for periodically energizing said Winding and elective each time when opened for causing the induction in the secondary winding of said" transformer of an impulse of current having a given relative polarity, a relay connected in series with said secondary winding to the rails at one end of said section, said relay being so con- Ystructed as to be immune to impulses induced in` said secondary Winding, a second source of unidirectional energy for energizing said relay, a winding connected in series with said second source to the rails at the opposite end of said sec-l l tion with said second source poled in opposition to current impulses from said transformer, and contacts operated by means responsive to the energization of said other winding effected by said current impulses but not by the steady supplyv of energy from said second source. I 4. In combination, a sectionA of railway'track, a track transformer having a primary Winding periodically supplied with unidirectional energy, a relay connected in series with the secondary winding of said transformer to the rails at one end of said section, a, receiving transformer having a secondary winding connected to a track relay, a source of unidirectional energy connected in series with the primary winding of said receiving transformer to the rails at the opposite end of said section, and signal control means operated vby said track relay in response to energy derived from the secondary winding of said receiving transformer.

5. In combination, a section of railway track, a source of unidirectional energy, a first relay means having a first winding connected in series with said source to the rails at one end of the section, said first relay means being responsive f only to energization of said rst winding eiected 'by energy'intermittently impressed on said track rails at the opposite :end of said section, a second winding and a second relay connected in series to the rails at said opposite end of said section, said second relay being responsive only to energy from said first source, a second source of unidirectional energy, contact means having a contact periodically, closed and opened, a third winding inductively coupled with said second Winding, a remotely controlled` relay, means controlled by said remotely controlled relay and said contact of said contact means for at times supplying energy from said second source to said third windingfor creating flux effective each time said contact opens to cause the induction in' said second winding of a relatively high peak voltage impulse,

6. In combination with a section of railway track, an impulse type track circuitfor said section comprising impulse translating means connected to the rails at one end and impulse transmitting means connected to the rails 'at the other end of said section, a reverse track circuit for said section comprising a source of energy connected to the rails at said one end and a track relay connected to the rails at said opposite end of said section, a control oflice'at a remote point, a communication system extending from said control ofilce to a station adjacent to said section, a control relay at said station manually controllable from said cnice over said communication systemI means controlled by said control relay for causing said impulse transmitting means tobe elective or ineffective to transmit impulses at the will of an operator at said oce, a signal governing traiiic in advance of said section, and means controlled by said track relay for approach energizing said signal whenl said section becomes oc- '7. In combination with a section of railway track, an impulse type track circuit for said section comprising impulse translating means connected to the rails at one end and impulse transmitting means connected to the rails at the other end of said section, a'reverse track circuit for said section'comprising a source of energy connected to the rails at said one end and a track relay connected to the rails at said opposite end of said section, a control oice at a remote point, a com- Y trac conditions in said section.

8. In combination with a section of railway track, a source of 'unidirectional energy and an impulse responsive relay coupled to the track rails at one end of said section, said relay being non-responsive to energy from said source, a second source of Yenergy and la second relay, a :cir-

cuit including the winding lof said second relay track rails, a control oflice at a remote point, a

'communication system extending from said office to a station adjacent to said section, a control relay at said station manually controllable from said office over vsaid communication system,

means governed by said control relay for causing said circuit to be eiective or ineffective to transmit impulses to the rails at the 'will of an operator at said olce, and means governed by said track relay for causing said communication system to transmit to said office information relating to trail'ic conditions in said section.

9. In combination with a section of railway track, a source of unidirectional energy and an impulse responsive relay coupled in circuit to the track rails at one end of said section, said relay being non-responsive to energy from said source, a second source of energy and a second relay, a circuit including the winding` of said second relay for inductively coupling said second source of energy to the rails at the opposite end of said section, means for causing said circuit to transmit impulses of relatively high peak voltage to said track rails, a control oiiice at a remote point, a communication system extending from said office to a station adjacent to said section, a control relay at said station manually controllable from said oice over said communication system, means governed by said control relay for causing said circuit to be effective or ineffective to tcansmit impulses to the rails at the will of an operator at said office, a signal governed by said impulse responsive relay for authorizing trailic movements in said section when said relay responds to said high peak voltage impulses, and means governed by said track relay for causing said communication system to transmit to said oflice information relating to traiiic conditions in said section.

10. In combination, a section of railway track having a relay connected in series with a secondary winding to the rails at one end of said section, a primary winding intermittently supplied with energy and inductively coupled with said secondary winding, said relay being non-responsive to energy induced in said secondary winding, a source of energy for energizing said relay, a control relay, a checking relay; a circuit including said source, a front contact and the winding of said checking relay for inductively coupling said control relay to the rails at the opposite end of said section; said control relay being responsive to energy induced in said secondary winding, a time element relay, an energizing circuit for said time element relay including a source of energy and a back contact of said checking relay, and a circuit path including an operated contact of said time element relay for providing a shunt path around said front contact of said checking relay in said circuit of said control relay.

11. In combination with a section of railway track, a source of current, a control relay, a checking relay, a circuit including said source and a front contact and the winding of said checking relay for inductively coupling said control relay to the rails of said section, a time element relay energized over a circuit including a back contact of said checking relay, said time element relay having a time contact which becomes closed at the end of a predetermined time interval of energization of said relay, and a circuit path including said time contact for providing an alternative path around the front contact of said checking relay in said circuit of said control relay.

12. In combination with a section of railway track, two batteries, a rst relay, a circuit including the winding of said first relay for inductively coupling one of said batteries to the track rails at one end of said section, another relay, a circuit connecting in series the winding of said other relay and the other of said batteries to the track rails at the other end of said section, said other battery being orientated to oppose the electromotive for-ce inductively applied to the track rails from said one battery, an asymmetrical unit connected in multiple with said other relay and poled to shunt current from said other battery away from said other relay, and another asymmetrical unit connected in multiple with said first relay and poled to shunt energy from said one battery away from said iirst relay.

13. In combination with a section of railway track provided at one end with a track transformer having its secondary winding connected across the track rails and its primary Winding energized from a source of unidirectional current over a coding contact operable to cause the induction in said secondary Winding of an impulse of relatively high peak voltage each time the coding contact interrupts the connection of said primary winding with said source, said track section having coupled across the track rails at the opposite section end a, track relay responsive to high voltage impulses of short duration, a neutral relay having its winding connected in circuit with said secondary winding of said track transformer across the track rails at said one section end, said neutral relay being immune to operation by said high voltage impulses, and a second source of unidirectional current interposed in the coupling of said track relay to the rails at said other section end for energizing said neutral relay, said coupling being arranged to avoid operation of said track relay by energy from said second source.

NORMAN AGNEW.