US2617921A - Checking means for wayside train control inductors - Google Patents

Description

Nov. 11, 1952 Clll CHANG CHU CHECKING MEANS FOR WAYSIDE TRAIN CONTROL INDUCTORS Filed May 2'7, 1950 in Haw xi aw kswwsww RSNEBE 1 1 m m w NRSE 5% km MM 3 w fl fin am INVENTOR. C1! CIzany Ubu y Z:

HIS ATTORNEY I Patented Nov. 11, 1952 CHECKING S FOR WAYS'IDE TRAIN CONTROL ,INDUGTORS Chi Chang Chuj, Pittsburgh, Pa,, assignor to- Westinghouse AirLBrake Gompany; a' corporation of Pennsylvania Applicationv May 27, 1950,.SeriaLNo. 164,685.

'13 Claims. 1

My invention relates. to automatic trainv controllsystem. of. theintermittent inductive type, and? particularly to meansfor checking the wayside. inductors iemplfoyednin such systems to insure that the inductor is in proper condition to cooperate with the. train-carriedapparatus.

'Tiain control systems of. this. type have inductorslooat'ed at the entrance of each track section. 'Eachrindjuctor has a Lie-shaped. core: having a winding. thereon. and. the inductors cooper.- ate with train-carried equipment so that if at the time the train passes over an inductor the circuit of'the winding isopen, or if current is flowing 'ina given direction through the inductor winding,..the train-carried equipment will operate to applyithebrakes, while if at the time the train passes. over. the inductor the winding of the inductor :isshort ci'r-cui'ted, or if current is flowingi'nthe opposite direction through'the inductor Winding, the train-carried equipment is not affected;

I'thas previously beenproposed to check the integrity of. the wayside inductor by providing a relay connected in series with, the inductor winding so that. if the. inductor is damaged or remove.d,.orthe circuitotherwise opened; the series checking, relay will. he released,- and; govern the associated signal-nor a signal inv the. rear; eitheinductor location to indicatev that the apparatus is ;not.. in. its proper condition. Howeveri it is' also necessary to check that the winding-of the:

inductor. does not become-short.circuited,. except by operation of. the controlling relays, since a short circuit inthe winding itself or-in the-com necting wires might resultinthe erroneousoperation of. the train-carried apparatus, so that with the associated wayside signal displaying;- a

restrictive indication, the train-carriediallparatus.

would. not be. operated to apply thehrakes.

Accordingly, ,it is-an object. of. invention to provide checking means for train oontrol ;inductors and. which means will detect whether. the inductoris improperly open or shortcircui-ted.

Another object of my invention is .to provide checking means for traincontrol inductors-which.-

will. detect an improperly open or shortrcircuited;

inductor, and which means providesior supply-.

ingenergy through the inductor winding in. such directionas to further-increase or decrease the fiuxinthe train-carried apparatusytofurtherinmeans is arrangedso thatyundersomeconditions,V

the inductor is checked, for an open-circuiteid winding, under other conditions the 'ihductoris checked for a short-circuitcd' winding and under still other conditions theinductor is checked for either an open-circuited winding, or a short-circuited winding.

Another object. ofmy invention. is, .tov provide. checking, means for train control ihductors,.,i'n which a low impedance path is provided for the alternating current energy induced in the ind'uc: tor by the passageiof the traincarriediapparatus;,. but a relatively high resistance pathi's. provided for theidirec't currentenergy employed in checking the condition of the winding, so that the in d'uctor appears short-ci'rcuitedi insofar as the train-carried apparatus is concerned.

Other objects of my invention and features of'novelty thereof will be apparent from therfollowing description, takenin connection withjthe accompanying drawing.

In. practicing my invention, I provide a. first. auxiliary relay;v having va winding of relatively low resistance, which may be governed. by the. control relays for the associated wayside signal; so that the winding. of the first auxiliary relayis connected i'nseri'es with thewindingofthe inductor .at' times to. thereby detect an open circuit failure of the inductor A second auxiliary,relay,.. having a winding of relatively high resistance is. provided, and may be adapted to be governed bythe signal controlrelays in suchmanner that the winding of the secondauxiliary relay is connected across the inductorvwinding, at times, in which case the second auxiliary relay is released .if the inductor winding is short circuit'ed; The circuits may be arranged so. that either the short circuit check". or the open circuit checker both are applied as determined by the signal control relay which governs the associatedwayside signal; In, order'to provide an equivalent shortcircuitedine ductor for the train-carried. apparatus, a con:- denser is connected across the inductor winding at times, to thereby ofier a low impedan-ce pathr for the energyinduced in the inductor windingeby the passage of the train-carried apparatus. Ad-

ditionally, the direct current energy which is passed through the inductor winding for checking purposes is arranged to flow in the proper direction to assist in properly influencing the traincarried apparatus. The checking relays may govern additional trafiic governing means in the rear of the inductor, to warn an approaching train that the inductor is not in proper condition.

I shall describe one form of checking means for train control inductor, which means is a preferred embodiment of my invention, and shall then point out the novel features thereof in claims.

The single accompanying drawing is a diagrammatic view showing a stretch of railway equipped with signals for governing movements of trafiic in one direction only, and having train control inductors for the control of trains moving through the stretch. It is to be understood that my invention may also be employed in connection with train control systems on single track railways where trafi'ic moves over the stretch in either direction, by providing similar a aratus for the inductors governing the traflic movements in the opposite direction.

Referring to the drawing, the reference characters I and 2 designate the track rails of a sectionof railway track, over which tra-fiic moves in the direction indicated by the arrow, that is, from left to right. The stretch is divided into sections such as section 2T, each of which has associated therewith a wayside signal, such as signal 2S, here shown as being of the well known color-flight type,, for governing the entrance of trafiic into the correspondingly designated track section. These wayside signals are governed by the occupancy of the first and the second sections in advance of the signal to provide a conventional two-block, three indication signaling system That is, when the first track section in advance of a signal is occupied by a train, the signal will display a red aspect, indicating stop; when the first track section in advance is unoccupied' and the second track section in advance of a signal is occupied, the signal will display a yellow aspect, indicating approach next signal prepared to stop; and when the first and second sections in advance of the signal are unoccupied,

the signal will display a .green aspect indicatin "clear." Each of the track sections is provided with a conventional direct current track circuit, including a track battery, such as battery ITB, connected across the rails at the exit end of the section, and a track relay, such as relay ITR, connected across the rails at the entrance end of the section, in order to detect the occupancy of the section by a train. Each of the signals has associated therewith a signal control relay such as relay ZHDR, which governs the associated signal in accordance with the occupancy of the track sections in advance of the signal.

Adjacent the entrance end of each track section, there is provided a trackway inductor designated by the reference character V preceded by, the numer of the track section with which the inductor is associated, for example, inductor 2V located at the entrance end of section 2T. Each inductor, as shown, comprises a ,core carrying a winding, and is adapted to cooperate with traincarriedapparatus in such a manner that an automatic application of the brakes occurs or a stop indication is given on a train passing an inductor which is effectively open circuited, but no effect is produced on a passing train when the inductor is effectively short-circuited. More-- 4 over, if a direct current is passed through the inductor winding in one direction or the other, it will tend to increase or decrease the efiect upon the train equipment, so that if the inductor is effectively open circuited insofar as the energy induced therein by the passage of the train equipment is concerned, and in addition, direct current energy is flowing in a given direction through the inductor winding, the effect upon the train-carried apparatus is increased over that produced by an inductor which is eifectively open circuited but does not have direct current flowing in its winding. A similar condition is found in the case of an inductor which is effectively short circuited insofar as the energy induced therein by the passage of the train equipment is concerned and has a direct current flowing therethrough in the opposite direction to that in which it flows when the inductor is effectively open circuited.

The train-carried apparatus is not illustrated because it forms no part of my invention, but it may be, for example, of the type shown and described in Letters Patent of the United States No. 1,698,470, granted to Paul N. Bossart on January 8, 1929.

Each of the inductors is provided with means for checking the integrity of the inductor, comprising a first auxiliary relay, such as relay ZHDPR, and a second auxiliary relay such as relay ZCKR. The circuits for governing these relays and the associated inductor and the circuits for supplying energy to the signal lamps are shown in detail for signal 28, but it will be understood that similar equipment is provided for each of the other signals and inductors in the stretch.

At each of the signal locations, energy for the operation of the various relays and signal lamps is provided from a suitable source of direct current, such as the battery LB shown, the positive and negative terminals of which are designatedv by the reference characters B and N, respectively.

The operation of the circuits associated with signal 28 under various conditions will now be,

described, and it will be seen that the circuits associated with the other signals in the stretch will operate in a similar manner.

The apparatus is shown in the normal condition, that is, the condition it assumes when there is no train occupying any section in the stretch.

At this time the winding of signal control relay ZHDR is supplied with energy by a circuit which may be traced from terminal B at signal, location 3S, over front contact a of relay 3HDPR,

front contact a of relay 2TB, through the winding of relay 2HDR from left to right, front contact b of relay 2TB, and front contact b of relay SHDPR to terminal N. Relay ZHDR is of the polarized type, having neutral contacts which are picked up when energy flows through the winding of the relay in either direction and are released when no energy is supplied to the wind-' ing of the relay, and also having polar contacts which are operated from a normal to a reverse position when energy is supplied through the winding of the relay in one direction, and are operated to their normal or left-hand position when the winding of the relay is supplied with energy of the opposite polarity. The relay is constructed and arranged so that with energy flowing through the winding from left to right, the polar contacts of the relay will be operated to their left-hand or normal position, and the neutral contacts will be picked up. Thefirst at tthis-itimeby a circuit which may be traced from: terminal B at .front. contact. a" of. .relay 2HDR, over normal contact 12 of relay 2HDR,.

back. contact a of. thesecon'd'auxiliary relay ZCKR, through: the. winding of relay ZHDPR fromtright to left,.front contact-.d of relay 2HDR,.

through the windinguof. inductor 237 from right. to sleft,=. and back contact d .of; relay ZCKR' "to terminal N. .Accordingly, relay 2I-IDPR will :have:

its-i contacts :picked up at this time.v A circuit.

for supplying: energy to the green lamp G of signal 28 may be traced'froml terminal Bat-front contact rd of. relay AHDPR, over normal contact I of relay -2HDR,.. andthrough the greenilamp G ofxisig'n'al 2S to terminal N. Accordingly, signal 2S-will. displayagreen aspect, indicating. fclearf Underathe normal condition, the relay |HDR.,. which governs signal IS, in the rear: of signal 28, in a similar manner to that in which relay 2HDRgoyerns signals 2S,.is supplied with energy by'aacircuit which may. be traced from terminal Bwatiront. contact b of relay ZHDPR, over front contact a; of relay 'ITR, through the winding of relay. l-HDR from left, to right, front contact I) of relay ITR, and front contact'c of relay ZHDPRto terminal N. Thus, it will be seen that relay IHDR, which is similar in construction ando'peration to relay2HDR, will have its neutral contactspicked up, and its p01arc0ntacts will occupy-their normal position, so thatsignal IS; will also display a green aspect.

.From: the foregoing, it will be seen that, with no train occupying the: stretch, the signals will each display a, green aspect indicating clear. When a signal is displaying a green aspect, it is "desired that the associated inductor such as inductor 2V will be in such condition that if a train moves by the inductor,. the. equipment on.

the train will not be afiected so that the train may continue on through. the, section. Accordingly, atv this time it is necessary that the inductor 2V be effectively short circuited insofar as energy induced in the inductor by the passage of the train-carried apparatus is concerned. In order toprovide this effective short circuit condition of the inductor, a condenser Q, which has a relatively large capacity, is connected across the winding of inductor 2V by front contact a of relay 2HDPR and normal contact e of relay 2HDR. The capacity of condenser Q is selected so that at the lowest frequency-of energy induced inrthe. inductor 2V, which would be that produced by a train moving by the inductor at a predeterminedrelatively low speed, the reactance of the condenser Q will be comparable to the reactance of the inductor 2V, so that the combination .of the inductor winding and the condenser forms a resonant circuit, and thereby the effective impedance of the circuit is reduced to that represented by the resistance of the winding and the various connections normally. At higher speeds, the frequency will of course be increased,

butthe reactance of the condenser will be lowered, so that by choice of a condenser of suitable value, say, for example, 4000 microfarads, the impedance may be kept relatively low for the range of train speeds involved. Accordingly, it will be seen that with the condenser Q connected across itswinding the inductor 2V is effectively short circuited insofar as the train-carried apparatus vis concerned. Moreover, as was previously pointed out, thecircuit is arranged so that the direct current energy which. flows through the inductor for providing energizatipn'v .ot

relay 2I-IDl=!mflows ithrouglt thesindiictor lnzsuch a zdirectionfithatl it prevents thezincrease .-.ofc-fiux in' astrain carried apparatus; as. the trainecarried.

apparatus -passes fthe inductor, which assists in:

preventing-operation. on the train-carried: equipment; sincethe condenserrQ isrconnectedacross. the inductor winding; at this. time, .it will ;be

charged by the directcurrent energy to some given.value. v This charge isautilized for: picking upxrelayfilfiKR;.as-willzbe-subsequently described.v

sin'ce under normal" conditions the signal is: is -cl'ear, and zthe iinductor- 2V should, be-short ci'rcuit'ed, it is not;necessaryto check the inductor winding; tor a :shortzeircuit; Accordingly; the: second auxiliary relay, .ZCKR. is: not connectedin the. inductor: circuit atxthis time.

It 'willbevseenzfromi the" foregoing,- that; when.

theisigna'ldisplays azgreerraspect'indicating;pro-- ceed, the inductor is. checkedutor, insure itssine tegrity, andtat the:v same: time iti-is:provided zwitha a relatively :low impedance: path. for" the=alter:-=

nating current energy induced 'insthetim'luctors.by.

the passage :of the trainecarried: 'requipment-,. sozthatshoulda: .train pass? theinductor at this time-no :operation of the "train-carried. apparatus will take place, .It will. further be seen that, should theinduc'tor 2V:.becomedisplacedfor. some reason or other by :sufficient. .amount that it-cno, longer wouldbein .a position to cooperate with. thectrain-carried: equipment, :such displacement of the inductor would likely cause abreak in'thea wires which connectthe-zinductor awindingwtocthe various relayw circuits,v and rtheqcircuit :for supply? ing; energytto relay 'ZHDBR: .Would 'beinterruptedi and the -relay-would releases In such-casathe contact at of relay :2HDPR would interrupt the: supply of. energy to the greenlamp G of signab 2S, ,and 1establish=v a circuit for. supplying. energy to the red lamp-Ref signal .25 over back contact" d. Moreoventhe contactsbandc of relay ZHDPR' wouldreversethe polarity of the energy suppliedoverrthe line. wires to-signal'control relay II-IDR which governs signal IS, so that signal IS would then; display a yellow aspect indicating ap proach, so that .a .train passing signal IS would be. prepared to; stop, at the-next. signal, inthis case; signal 28. Accordingly, itwill be seen thatwith .the apparatus :arrangedas :described, the: inductor 2V iseifectively checked against an open circuit, or a. displacement from its proper positio n-;bya suflicient-amountto break the connectnsi:W res-.

It will now be assumedi'that aitrain, moving from left to right, passes the inductor 2V and the signal 2S and enters section. 2T with signal 23 displaying a green aspect. Whenth'e train enters section 2T, track relay ZTR, will release, and its contacts a and b will interrupt the circuit for supplying energy to the signal control relay 2HDR, and the neutral contacts of'relay ZHDR will release. When contact. a of relay 2I-IDR releases, the circuit previously traced for supplying energy to the first auxiliary relay ZHDPRis interrupted, and relay ZHDPR. will release. The: circuit for supplying energy to relay 2I-IDPR is additionally interrupted byzfront contact (1 ofre-- lay ZHDR.

When relay ZHDPR. releases, its front contact a disconnects the condenser Qfrom the inductor 2V and its back contact a establishes a pick-upcircuit for supplying energy previously stored in the condenser Q to the lower winding ll of relay 2CKR. This pick-up'circuit maybe traced from the right-hand plateuot' condenser Qyove'r' back-contact a 0f-.relay.2I-IDPR,..and through-the winding [1 of' relay 2CKR from left .to right to the left-hand plate or element of condenser Q.

Accordingly, the energy previously stored in condenser Q when it was connected in the circuit for inductor 2V is now discharged through the winding l! of relay 20KB, and the parts are proportioned and arranged so that the value of this energy is sufficient to cause the contacts of relay ZCKR to pick up. When contact b of relay ZCKR picks up, 9, stick circuit is established for supplying energy to the upperwinding l5 of relay ZCKR, which circuit may be traced from terminal B at back contact a of relay 2HDR., over front contact 1) of relay ZCKR, through the winding [5 of relay ZCKR from left to right, normal contact of relay ZHDR, front contact 0 of relay ZCKR, and through a reactor L to terminal N. Accordingly, the contacts of relay ZCKR. will be retained picked up, after the condenser Q has dissipated all of its charge through winding I! of relay 2CKR. Moreover, at this time, energy is supplied to the winding of inductor 2V by a circuit which may be traced from terminal B at front contact d of relay 20KB, through the winding of the inductor 2V from left to right, over back contact d of relay 2HDR., front contact c of relay ZCKR, and through the reactor L to terminal N. It will be apparent that the winding l of relay ZCKR and the winding of inductor 2V are effectively energized in multiple atthis time from the direct current source.

The resistance of the winding I5 of relay ZCKR is-selected and proportioned so that it has a rela-" tively high resistance in comparison with the resistance of the winding of inductor 2V. The parts are proportioned so that. as long as the winding of inductor 2V is intactand not short circuited, the current which flows through winding l5 of relay ZCKR is sufficient to keep the contacts of relay ZCKR. picked up. However, if the winding of inductor 2V should become short circuited for any reason, it will effectively shunt the winding it of relay 20KB, and the current flow through winding l5 of relay 20KB will be reduced to the point where the relay will release its .contacts. If relay ZCKR, becomes released due to a short circuited inductor, contact b of the relay opens the stick circuit previously traced,

so that the relay remains released. It will be seen therefore that the second auxiliary relay ECKi-t serves to determine whether or not the winding of inductor 2V is short circuited when the train occupies the section 2T.

-When signal 2S is displaying a red aspect due to the train in section 2T, the inductor 2V should represent an effective open circuit for any traincarried apparatus which may pass the inductor. The reactor L, which is connected in series with thewinding of inductor 2V, is proportioned and arranged so that although it affords little resistance to the flow of the direct current energy through the inductor winding, it will present a relatively high'irnpedance to alternating current energy induced in the inductor by the passage of train-carried equipment. Also, the winding I5 of relay 20KB, which is now connected across the winding of the inductor, presents a relatively high impedance to the alternating current energy induced in the inductor due to the passage of the train-carried equipment. Accordingly, insofar as the train-carried apparatus is concerned the inductor 2V is opencircuited at this time, and should a train proceed past the inductor the train-carried apparatus will operate to initiate an automaticflbrake application. Moreover, it

will be seen that the flow of direct current energy through the winding of inductor 2V at this time is in the opposite direction'to that previously traced when signal 28 was displaying a "clear aspect. The parts are proportioned and arranged so that the flux set up by the current flow through the winding of inductor 2V at this time is such as to cause an increase in the flux in the train-carried apparatus, thereby further assisting in providing the proper operation of the train-carried equipment to initiate an automatic brake application if it passes the inductor.

With the signal 28 at stop, it will be seen that it is not necessary to check the inductor winding for an open circuit, as relay ZHDPR is already released due to the fact that relay 2HDR. is released, so that the signal IS in the rear of signal 2S is already displaying an approach aspect because signal 2S is displaying a stop aspect. I

When the train vacates section 2T and is occupying section 3T, relay 2TR will pick up, and at this time relay SHDPR is released, so that energy of the opposite polarity is supplied to relay 2HDR. Accordingly, the polar contacts of relay 2HDR. will be operated to their reverse position following which the neutral contacts of the relay will pick up.

It will be seen that the relay ZCKR. is retained relay ZCKR and through the reactor L to terminal N. Then when the neutral contacts of relay 2HDR. pick up a stick circuit is completed from terminal B over front contact a of relay 2HDR., reverse contact 12 of relay ZHIDR, front contact I) to relay ZCKR, through the winding l5 from left to right, reverse contact 0 of relay 2HDR, front contact d of relay 2HDR., through the winding of relay ZHDPR from left to right and front contact a of relay ZCKR to terminal N.

At this time, the relay ZHDPR is also energized by a second circuit in multiple with the above traced stick circuit for relay 20KB. and which second circuit can be traced from terminal B at front contact 11 of relay ZCKR, through the winding of inductor 2V from left to right, front contact d of relay 2I-IDR, through the Winding of relay ZHDPR from left to right and over front contact a of relay ZCKR to terminal N.

Accordingly, it will be seen that the second auxiliary relay ZCKR is effectively connected-in multiple across the winding of inductor 2V, and the winding of relay 2HDPR is effectively connected in series with the winding of inductor 2V when the section 2T is unoccupied-and the sections, a circuit is established for supplying energy to the yellow lamp Y of signal 2S, which circuit a may be traced from terminal Bat front contact d of relay ZHDPR, over reverse polar contact I of relay ZHDR, and through the yellow lamp Y of signal 2S to terminal N. Accordingly, signal 25 at this time will display a yellow aspect indicating acm ar approach the next signal prepared to stop. With reIa-y-ZHDPR picked up, its contacts band establish a circuit for supplying energy of normal polarity over the line wires and. contacts a and b of relay ITR to the winding of relay IHDR, so that signal IS in the rear of signal 28 displays a green aspect indicating clear.

The winding of relay ZHDPR which is now connected in series with the winding of the inductor 2V with the battery presents a relatively high impedance to the alternating current energy induced in the inductor due to the passage of a train-carried equipment. Also, as stated hereinbefore, the winding l5 of relay ZCKR, when it is connected across the inductor winding presents a relatively high impedance to the ener'gyinducedin the inductor by a train-carried equipment. It follows that the inductor 2V is in effect open circuited when the signal 28 displays its yellow aspect and should a train moving from left to right pass over the inductor it will initiate an automatic brake condition on the train. It is tobe pointed out that in train control systems of thetype here involved the equipment is usually arranged so thatan automatic brake application is initiated when a train passes over an inductor at an approach signal. It is to be observed that these train control systems are generally provided-with means wherewith an automatic'brake application can be forestalled by the proper operation of the apparatus on the train by the en- 'gineman.

If at this time the inductor 2V should become displaced or damaged in such manner as to break the circuit including the inductor winding, the supply of energy to the winding of relay ZHDPR will be interrupted and the contacts of relay Z HDPR will be released. When contact d of relay 2HDPR'releases it establishes the previously traced circuit for supplying energy to the red lamp R of signal 28, and additionally, its contacts b and c pole change the energy supplied to relay IHDR so that signal IS displays a yellow aspect. Accordingly, the inductor W at signal location I S is placed in condition to cause an automatic application of the brakes of a train which passes the signal at this time, so that the train will be stopped before reaching the damaged or displaced inductor. Moreover, if the inductor 2V or the wires connecting the inductor'with the apparatus become short circuited, the resulting short circuit will effectively shunt the supply of energy from the winding l5 of relay ZCKR, so that relay 2CKR will release its contact. With polar contact I) of relay 2HDR in its reverse position, if contact a of relay ZCKR becomes released the supply of energy tothe winding of relay ZHDPR is interupted, so that the'signal 23 is governed to display a red aspect, and the signal IS in the rear of signal 28 is governed to display a yellow aspect.

It will be seen, therefore, that in the event of a displaced, damaged or short circuited inductor at any of the signal locations in the stretch, the associated signal will be governed to display a stop aspect, and the next signal in the rear willv be governed to display a yellow aspect, and additionally, the inductor associated with the signal in the rear of the damaged inductor will be placed on an open circuitstatus, to initiate the application of the brakes of a train passing the signal.

Whenthe train; inquestion clearssection 3T:in advance of signal 38, the relay J3HDPR, whichis controlled ma mannensimimrto:re1ay'i2IiDPR.

will become pickedup, thereby pole. changing the energy supplied to relay ZHDR. When the polarit-y of the energy supplied to relay 2HDR is reversed, the neutralcontacts of relay ZHDR release, the polar contacts areoperated to their normal position, and "thereafter-the neutral con.- tacts of the relay pick up again, in the well known manner of operation of polarized relays and the apparatus is restored to its normal. condition as shown in the drawing.

'When the apparatusis restored to .normal energy is supplied to the winding of relay 2HDPR by the circuit previously traced and by which circuit the direction of the flow'of currentthrough the winding of relay ZHDPR, is reversed from that flowing ln-the relay when the signal 28 displays its yellow aspect. The reversal of directionfof current flow through the circuit including the winding of relay 2HDPR at this time does not result in the release of the contacts of relay zHDPR, since thisrelay "is of theretained-armature type, that is, the relay is constructed and arranged so that the-contacts do not release when the supply of energy to the windingof the relay is reversed, provided that such reversal occurs within a predetermined time interval, which -interval "is longer than the time of reversal of-the contact of-the polarized relayZI-IDR. Accordin'ga ly, the contacts of relay 2HDPR in the lighting control circuit for signal 2S and the pole changing contacts in the circuit for governing relay lI-IDR of the signals in the rear do not release at this time, so that the signal ZS is prevented from displaying a momentary red aspect --whil e theindication is changing from yellow to green and signal IS continues to display a green aspect. With contact 11 of relay ZHDR picked up and normal polar contactf of relay ZHDR closed, thecircult for supplying energy to the green lamp G is again established, so that signal 2S again displays a green aspect.

It will be seen from the foregoing, that I have provided checking means for wayside inductors of an automatic train control system, employing a low resistance relay adapted'to be connected in series with the inductor attimes, and a high resistance auxiliary relay adapted to be connected in multiplewith the winding of the inductor at times, to thereby check the'inte'grityof the connections to the inductor winding, and to .continuously provide detection of ,an open circuited inductor; a short circuited inductor, whether caused by mechanical derangement of the inductor or its winding.,,o r a short or an opencircuit in the wiring which connects the inductor with the wayside relay.

Although I have herein shown and described only one form of checking means for train control inductors, it is to be understoodthat various changes and modifications may be madetherein within the scope of. the appended claims with,- out departing from ithespiritandscope of my invention.

Having -thus described my invention, what *I claim is:

'1- In combination with a wayside'tra-in' control inductor winding susceptible to-open or-short circuit conditions, checking means for determining whether or not said inductor winding is open circuited or short circuited, comprising a source of energy, a firstauxiliary relay having a glow resistance winding and a second auxiliary -rel-'ay havinglaihigh resistance-winding,"a first tmeans for selectively connectingsaidflow ance'winding of said first :auxiliaryrel-ayan' inductor winding in series across said source, a second circuit means for selectively connecting said high resistance winding of said second auxiliary relay across said inductor winding, said first auxiliary relay being arranged and proportioned so that its contacts are released when said inductor winding is open circuited, and said second auxiliary relay being arranged and proportioned so that its contacts are released when said inductor winding is short circuited, and indicating means governed by said first and second auxiliary relays.

' 2. In combination, a wayside train control inductor winding susceptible to open or short circuit conditions, checking means for determining whether or not said inductor winding is open circuited or short circuited, comprising a source of direct current energy, a first auxiliary relay having a low resistance winding and a second auxiliary relay having a high resistance winding, first circuit means for selectively connecting said low resistance winding of said first relay and said inductor winding in series across said source, second circuit means for selectively connecting said high resistance winding of said second relay across'said inductor Winding, a capacitor, and means for selectively connecting said capacitor across said element for effectively short circuiting said element with respect to alternating current.

3. In combination, a wayside train control inductor winding susceptible to open or short circuit conditions, checking means for determining whether or not said inductor winding is open circuited or short circuited, comprising a source of direct current energy, a first auxiliary relay having a low resistance winding and a second auxiliary relay having a high resistance winding, said high resistance winding having a high reactance, first circuit means for selectively connecting said low resistance winding of said first relay and said inductor winding in series across said source, second circuit means for selectively connecting said high resistance winding of said second relay across said element, a reactor, and means 'for selectively rendering the impedance of said first circuit means comparatively high with respect to alternating current comprising means for selectively connecting said reactor in series with said low resistance winding of said first relay.

4. In combination, a wayside train control inductor winding susceptible to open or short circuit conditions, checking means for determining whether or not said inductor winding is open circuited or short circuited, comprising a source of direct current energy, a first auxiliary relay having a low resistance winding and a second auxiliary relay having a high resistance winding, said high resistance winding having a high reactance, first circuit means for selectively connecting said low resistance winding of said first relay and said inductor winding in series across said source, second circuit means for selectively connecting said high resistance winding of said second relay across said element, means for effectively short circuiting said element with respect to alternating current, comprising a capacitor and circuit means for selectively connecting said capacitor across said element, and means for selectively rendering the impedance of said first circuit means comparatively high with respect to alternating current comprising a reactor selectively connected in series with said low resistance winding of said first relay.

.5. ,In combination, a train control wayside device located along a stretch of railway track, a control circuit for said device, said device being adapted to assume its active train-stopping condition unless said control circuit is closed to present a relatively low impedance to alternating current induced in said device, a control relay for governing said control circuit in accordance with traffic conditions of said stretch of track in advance of said wayside device, a first auxiliary relay having a low resistance winding, a second auxiliary relay having a high resistance winding, first circuit means governed by said control relay for selectively connecting said low resistance winding of the first auxiliary relay in series with said control circuit, second circuit means governed by said control relay for selectively connecting said high resistance winding of the second auxiliary relay in multiple with said device in said control circuit, a source of direct current energy having connections to said control circuit governed by said control relay, whereby said first auxiliary relay is energized when the control circuit for said device is not open circuited and said second auxiliary relay is energized when the control circuit for said device is not short circuited, with respect to energy supplied from said source, and traffic governing means in the rear of said device governed by said first and said second auxiliary relays.

6. In combination, a train control wayside device having a control circuit and adapted to assume an active condition unless said control circuit is closed to present a relatively low impedance to alternating current, a control relay for governing said control circuit, a source of direct current energy, a first auxiliary relay having a low resistance Winding, a second auxiliary relay having a high resistance winding, first circuit means governed by said control relay for selectively connecting said low resistance winding of the first auxiliary relay in series with said source in said control circuit, second circuit means governed by said control relay for selectively connecting said high resistance winding of the second auxiliary relay in multiple with said source and said device in said control circuit, and traffic governing means in the rear of said device governed by said first and said second auxiliary relays.

'7. In a train control system, in combination, a wayside train control inductor located alon a stretch of railway track having a winding and arranged to assume its inactive non-stopping condition when said Winding is efiectively short circuited with respect to alternating current induced in said winding, and to assume its active stopping condition when said winding is effectively open circuited with respect to alternating current induced in said winding, a control circuit for said winding, a control relay governed by trafiic conditions in said stretch in advance of said inductor, means including said control relay for effectively opening or closing said control circuit to effectively render said winding open circuited or short circuited for alternating current induced in the winding, and checking means for determining if said inductor is open circuited or short circuited, comprising a first auxiliary relay having a winding connected in series with said inductor winding, a second auxiliary relay having a winding connected in multiple with said inductor winding, means including a source of direct current energy for energizing said first and said second auxiliary relays, and means governed by said first and second auxiliary relays for indiicating' he open circuited bra-short circuitedcondition 'ofsaid inductor wimiing.v

circuit -or-a short circuit, said checking means comprising a source of direct current, a first auxiliary relay, a second auxiliary relay, first circuit means governed by said control relay for connecting a winding of said first auxiliary relay inseries with said winding of said device and said source. second circuit means governed by said control relay for connecting a winding of said second relay across the said winding of said device in multiple with said source, a condenser governed by said control relay, third circuit means for connecting said condenser across the winding of said device, a reactor, fourth circuit means for connecting said reactor in series with the winding of said device, and a circuit governed by said first and second auxiliary relays.

9. In a railway signaling system for a stretch of track comprising a wayside inductive trafiic controlling device for transmitting control influences to a moving vehicle under adverse traffic conditions ahead including a winding which if effectively short circuited by a circuit having a low impedance to alternating current places said device in its inactive condition, control means for said device, and traific governing means located in the rear of said device, the combination with the foregoin of checking means for determining if said winding is defective due to an open circuit or a short circuit, said checking means comprising a first auxiliary relay having a low resistance winding, a second auxiliary relay having a first and a second winding, said first winding of said second auxiliary relay having a relatively high resistance, a source of direct current, a condenser, a reactor, first circuit means governed by said control means for selectively connecting said low resistance winding of said first auxiliary relay in series with said winding of said device and said source, and for connecting said condenser across said winding, second circuit means governed by said control means for selectively connecting said condenser to the second winding of said. second relay for picking up the second relay by energy stored in said condenser, and for connecting said first winding of said second relay in multiple with said source and the winding of said device by a stick circuit including in series a contact of said second relay closed when the second relay is energized, third circuit means for selectively connecting said first relay winding in series with said source, said reactor and the winding of-said device and said first winding of said second relay in multiple with the winding of said device, and circuit means governed by said control relay, said first auxiliary relay, and said second auxiliary relay for controlling said trafiic governin means in the rear of said device.

10. In combination, a train control wayside inductor having a winding and adapted to assume a restrictive or non-restrictive condition according as it presents in effect an open circuited or short circuited condition of its winding as far as alternating: current induced the :winding is concerned, a control relay operable to a firstor asecond position to represent arestri'ctive anda "for alternating current, checking means including an-auxiliary relay and a source of direct-current, a second circuitincluding first position contacts of said controlrelay to connect -a winding of said auxiliary relay and said inductor winding in multiple across said direct current source, said auxiliary relay being energized when said inductor winding is open circuited and deenergized when said inductor winding is short circuited.

11. In combination, a train control wayside inductor having a winding and adapted to assume a restrictive or non-restrictive condition according as the inductor presents a relatively high impedance or a relatively low impedance to alternating current induced in said winding, a capacitor, a direct current source, an auxiliary relay, a control relay, said control relay being operable to a first and a second position to represent a restrictive and a, non-restrictive traific condition, respectively, a first circuit including second position contacts of said control relay to connect said capacitor across said inductor winding for the inductor to present its non-restrictive condition, a second circuit including first position contacts of said control relay to connect a winding of said auxiliary relay and said inductor winding in multiple to said direct current source when said inductor is disconnected from said capacitor to present its restrictive condition, said auxiliary relay being shunted and released in response to said inductor winding being short circuited.

12. In combination with a Wayside train con trol inductor winding susceptible to open and short circuit conditions, checking means for determining whether or not said winding is open circuited or short circuited, comprising a source of energy, a first auxiliary relay having a low resistance winding, a second auxiliary relay having a high resistance winding, a first circuit including in series said source of energy, said low resistance winding of the first auxiliary relay,

and said inductor winding, a second circuit in-' cluding in series said source of energy and said high resistance winding of the second auxiliary relay and said inductor winding connected in multiple, control relay means, said control relay means having contacts operable to different positions in response to different conditions, said contacts being interposed in said first and said second circuits to govern the operation thereof, and indicating means governed by said first and said second auxiliary relays.

13. In a train control system having a wayside train control inductor provided with a winding and eiiective to assume a non-stopping condition when said winding is effectively short circuited with respect to alternating voltages induced therein and effective to assume a stopping condition when said winding is eliectively open circuited with respect to alternating voltages induced in the inductor winding, said system having a control relay governed by traffic conditions and provided with contacts operable to a first and a second position in response to a first and a second trafiic condition respectively, and a control circuit for said inductor winding which circuit is closed or open according as said control .relay contacts are operated to said first or second positions, checking means for said wayside inductor comprising, in combination, a first and a second auxiliary relay, a source of direct current,

' a first checking circuit including in series said irect current source, a winding of said first auxiliary relay, said inductor winding and contacts of said control relay closed in their first position, to thereby check an open circuit of the inductor winding, a second checking circuit including in series said source of current, a winding of said second auxiliary relay and said inductor winding in multiple, and contacts of saidcontrol relay closed in their second position, to thereby check a short circuit of said inductor winding, and traffic governing means governed by said first and second auxiliary relays.

l CI-II CHANG CHU.

REFERENCES CITED The following references are of record in th file of this patent: 1

UNITED STATES PATENTS Name Date Number Thompson et a1. Dec. 20,1927

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