US2561956A - Normally deenergized coded track circuit signaling system - Google Patents

Description

C. E. STAPLES NORMALLY DEENERGIZED CODED TRACK July 24, 1951 I CIRCUIT SIGNALING SYSTEM Filed April 6, 1948 6 Sheets-Sheet l IN VENTOR.

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kw Emma QFWWAQ E g Q mwmmfiw wmwwvw W a $1 Patented July 24, 1951 UNITED STAFF-ES Par 1' OFFICE My; invention relates i to a centralized traific controlsystem for railroads embodyinga block signaling system of the reversible-coded-track circuit type.

In Let ters Patent of the United States [not 2,353,421, granted tome on July ll, 1944, which patent was reissued as No.- Re.22',93l on :Novemher 4, 194?,there is-showna normally deeneh gizedcoded track circuit signaling system-"for single track railroads. The system-of thispatent 1 0 isadapted to he; governed manually fr'om-a-remote control office, and is arranged sothat \vhen a control for clearing thesignalgoverning entrance of traffic into the stretch at either end is exercised, an impulse of actuating energy is supplied to the rails of "the stretch at the endat which the signal is located. "This impulse. is repea'ted or'cascaded to the opposite end ..Wl'iere it operates a codes'ending relay to cause-coded track circuit energy to be supplied over the rails ofthe stretchtowardthe signal which is to be clearedin addition, the system of myvpatent is arranged so that when the coded track circuit equipment is operating and the head lilo'ckj'signal for the corresponding traiiicdirection is' held at stop,:feed-back code is supplied to 'the entrance end of the stretch, and, when the stietch is vacated, is cascaded or repeated to the 'xitl'end of the stretch where'it restores the codesending relayto normal to" unto-mintethe" suppmti 3O codedenergy tothe stretch and thereby" restore the coded track circuit equipment to" 1ts"nor- "mally deenergi'zed condition.

'An 'o-bje'c't' of this'iiivention'is' tojprovide" an improved system of the"type described infmy patent, Which-is suitable foruse' with track "c'ircults of much greater 'length andof morevariable characteristics. Although the presents'ysftenr usesthe same code frequencies of 75' and 1 80 impulsesv per minute as hei etoforeflthe ISO 40 v code is'u'sed to but alimited extent andf'only th'e lower code frequency of 75"impulses"'per"minute -is used in the longer intermediatetrack circuits and for the control of the head block signals.

The'principal feature of the present invention l ahdd'e ie the "provision of improved actuatin s'toringmeans not requiring the'use er back impulses, which being relatively shertl'a're' more 's'iibfct to-distb1'ti0h "and cannot be reliably ""8 Claims; (Cline-=3) manual control of the associated signal control relay toits signal clearing position, to supply to the rails a code of very low frequency impulses, eachof "which is substantially longer than any impulse of a signal control code. 'Each code sendingl-relayfthe operation of which initiates the operation of the system, is of the slow pick-up type, and is arranged so that it assumes its energized'position when the associated track relay is energized by an actuating impulse but not when such relay is operated by signal control code impulses. "The code detecting relay governed by the same track relay does'not'respond td'an actuating code but only to a signal control code requiring a plurality of movements oi'the' contacts of the track relay within a predetermined timefinterval to cause it to assume its energized position. The actuating meansis'also arranged ,so' tha't if "the" firstimpul'se of actuating energy suppliedy-toian end 'of the stretch does "not --iiiiti'ate" operation of the coded track circuit equipment, other impulses of actuating energy Will be supplied to the stretch at suitable intervals untilo'p'eration of'the'cooled track" circuit equipment is initiated or untilthe control'for "clearing the'head block signal'iscancelled. In addition; the actuating code'isarranged so that "the-intervals between theimpulses of actuating energysupplied to an end of the stretch are long enough toflpermit coded energy to be cascaded "throughout the stretch to thereby indicate "whether one actuating impulse-has been" effective Tlieforefanother' is supplied to' the stretch.

"The improved restoring means provided in accordance, with the. present invention" operates by supplying afdistinctive"restoring code" of Widely {.SDaGd". long} impulses" of current, each iollowed byalplurality'of 75 codes impulses, to the rails of the stretch at the entrance end. This restoring means is set into operation, like thefeed 'bajck ja'pparatu's'of'my patent, the reception oi-coded "signaling currentfroni the exit end'of the stretch ata time when the entrance end signal control (relay is" in its normal position. "However; the track ,circuit apparatus of the present case differs" from that Of'the patent in "that it is not adapted totransinit impulses over therailsconcurrentlyi in two directions, but on the contrary, it l is soarranged'thatthe energization of any track transmitted'oven'track' circuits of the length 'relayduring an interval between impulses su'pcontemplated.

. The improved actuating means provided-in I accordance With the present invention comprises a pair 'of actuatingrelays at each 'endf fof ithe v.pliejdfto tl ieirailsxof its section by the associated ,tra ns'mitter'stops'iits further operation. Due to 'thiserrangement; "the *long'impulse transmitted bythe restoring means of my invention is *ableto i vstfetch, Which are 'set' 'intooperation"by the v'joverridefthe"signal control code andto reverse 4 vided with a code following repeater such as the relay BRTPR, Fig. 1B, which responds to the pulses of signal control energy repeated by the track relay and governs a code detecting relay such as relay 2Rl-IR by means of which the head block signals ZRA and ZRB are controlled in accordance with trafiic conditions in the single track stretch. Each code detecting relay'is enerized in a conventional manner by rectified pulses an undesired operation of either the signal or the restoring means at that end of the stretch, as

long as the adjacent code sending relay is ener-v gized and for a substantial time interval follow ing its release.

Since only low frequency impulses are used it will be evident that the means for restoring the coded track circuit equipment to its normally desupplied through a decoding transformer such as 2RDT, which is supplied with energy by a slow "release 'repeater relay GRTFPR of the code following repeater of the track relay. As shown, the head block signals indicate proceed or stop, and

require control by 75 code only, but each signal in the rear of a high speed signal, such as the signal 'IES or GWS, Fig. 10, serves as a distant signal energized condition operates in such manner that it does not limit or reduce the length of the track sections which may be employed in a track stretch equipped with this signaling system.

Another object of the invention is to provide a system of the type described which is arranged so that the means for restoring the coded track circuit equipment to its normal deenergized condition is positive in operation so that it is certain to operate when its operation is required, and so it will not operate to deenergize the coded track circuit apparatus improperly.

A further object of the invention is to provide a system of thetype described which incorporates improved means for governing indication means at a central control ofiice for indicating occupancy of the track stretch.

This feature of my invention includes the provision of an indication control relay at each end of the stretch which is picked up by the associated code detecting relay when the stretch is prepared for traflic in the corresponding direction, and which is released upon the operation of the associated restoring means to discontinue the operation of the stretch. When picked up, the indication control relay enables the associated code detecting relay to govern a block indicator at the central office to indicate block occupancy, in such manner that the indicator is controllable only when the system is active and then only from the entrance end for the direction established.

Another object of the invention is to provide a system of the type described and incorporating improved means for governing electric locks on hand-throw switches at intermediate points in a track stretch.

Figs. 1A, 1B, 1C, 1D and 1E, when placed together in the order named with Fig. 1A at the left are a diagram of a stretch of single track railway equipped with signaling apparatus embodying my invention, and

Fig. 2 shows the apparatus at the control office employed in connection with the system shown in Figs.1A to IE, inclusive.

In practicing my invention I provide each track section in a single track stretch with two sets of coded track circuit apparatus, one for each direction of traflic.

Each set of this apparatus comprises a transmitter relay such as the relay ELCTP, Fig. 10, which is adapted to supply energy to the rails of its section and to periodically interrupt such energy at a selected code rate such as '75 or 180 times per minute, for signal control purposes, together with a code following track relay at the opposite end of the section, such as the relay GRTR, Fig.

1A. Each track relay at a signal location is protherefor and is arranged to indicate proceed only when the signal in advance indicates proceed or caution. For this purpose code is supplied to the rails of the section which energizes a second code detecting relay such as the relay 6-'-'iDR."

Fig. 10, which relay is-controlled through a resonant decoding unit 180DU so as to respond to 180 code only. At each end of the stretch I provide actuating impulse generating means of a novel type for setting the coded track circuit system into operation by entrance end control, embodied in the actuating relays ZRSPR and 2RSPAR, in Fig. 1A, and in the similar relays ALSPR and GLSPAR, in Fig. 1E, which is rendered active on operation of the adjacent signal control relay 2RHSR or ELHSR to its reverse position for the purpose of clearing the head block signal at the corresponding end of the stretch. Each actuating impulse generating means, when rendered active, governs the associated transmitter relay to cause energy to be supplied to the rails of the stretch for a relatively long period and to thereafter discontinue the supply of energy to the rails of the stretch for a similar period after which the cycle is repeated indefinitely unless coded energy is received over the stretch to show that an actuating impulse has been effective, or the signal control relay is restored showing that the operator no longer wishes to clear the head block signal. These impulses thus constitute an actuating code in which the impulses recur at a relatively slow rate such as five cycles per minute. The coded track circuit equipment is arranged so that on the supply of an impulse of actuating energy to an end of the stretch it is repeated or cascaded to the opposite end of the stretch where it causes the track relay to operate a code sending relay ALCSR, in Fig. 1D, or 2RCSR, in Fig. 1B, the energization of which sets the adjacent transmitter relay into operation at the 75 or 180 code rate to cause coded energy to be supplied to the track stretch, whereupon the coded track circuit apparatus for the successive sections becomes energized in cascade to clear the head block signal at the other end of the stretch.

When a train enters the stretch, the head block signal is put to stop and the control relay therefore is restored to normal, and, when the coded track circuit equipment shows that the stretch has been vacated, the equipment at the entrance end of the stretch operates restoring means of a novel type at the entrance end, embodied in the restoring relays ZRRR. and 2RRPR, in Fig. '1B, and in the similar relays ARRR and lRRPR, in Fig. 1D, which serve to supply to the rails of the stretch deenergizing current which is cascaded or repeated to the exit end of the stretch where it restores the code sending relay to normal to cut off the a supply of coded energy to the-stretch. Theideenergi'zing current comprises a' long pul's'enf steady energy which is supplied at the entrance 'end of "the stretch and over-ridesor feeds through' the coded energy supplied from the exit'end of thestretchand cutsofi the supply of this coded'energ'y. The long impulse of steady energy's'upplied to the entrance end or the stretch by the restoring "means is followed by a short'pe 'ridd er codedenergy which is cascaded or repeat- 16 'tnrau'g'nout the stretch and restores the code f ding relaytonor'mal so that the coded track circuit equipment is restored to its normally'deen er'gized condition when the coded energy portion oi' the'deenergizing current ceases.

f' 1he' equipmentat' each end of the stretch inchides an indication control relay 2RFSR or 4138B. which is operatedwhen the stretchis prepared for "t'raffic and controls the transmission hf indication'cod'es to the office to show thatthe stretchhas been prepared for trafficand to "also showwhether the stretch is occupied. I

'I he equipment at each end of the stretch also includes means governed. by a switch lock control 'relawRWLS-or BLWLS for converting an end item an entrance to an exit end to governthe release of locks on hand-throw switches atinte'rmediate points in the stretch and to also govern in Fib. 1B, and statiOns'S-i, in Fig. 1D,. located atbrbpcisite ends of the single track stretch 'eci'uip'pedwith the signalingapparatus provided byf-this invention.

It is to be understood that the office and field stations are connected over a pair of line wires,- not shown, by a "code communication system whiehinay be of the type shown in Letters Patent of the" United-States No. 2,229,249, issued'January 2l-, -1-94l,'tol loyd VuLewis, or in Letters Patent ottheUnited States No. 2,411,375, issued'November 1'9,-'-1946,- toArthur P. J ackel and described in MaHual-EOBAOFThe Union Switch and Signal Eempany.

Gcinsiole'rationof the detailed mode of"operationof the'code' communication system is not needed for 'anunderstanding of this invention seems deemed sumcient to point out that a field station is "provided at each end of each track stretch"to be-controlled and that'coding units are provided at'the ofiice and at each field'station and are connected by a-pair of line wires, not shown, dver which control codes are transmitted at times from the ofiice to a selected field station, asthe is lt-of pr'essing a starting button l-2STB or EMSTB-bnthe correspondingpanel and that at 'other times indication codes are transmitted ever: the same'line wires 'from the difierent field stations to theofiice without interference. Transmission of each'code includes the temporary es tablishment'of a plurality of communication" channels, such 'for example, I as seven, between the ofiice-anda station to position a group-of relays.

- -Eac'h code includes adistinctive code call by means or which one station only is selected to effect teinporary establishment of seven communication 'chann'els between the office and the Sta tien. The different stations have different code eau -ebfisequenuythe different stations, -orfthe 'with asuitable source of direct current such as a storage battery," not shown, theterminals of which are designated B and C in the drawings.

-.'I'o'iIlustratethe operation of the signal and switch lock-control relays at the stations by-controfcode pulses of reversible polarity, a-second source of current is shown in Fig. 2, havinga position terminal B, a center terminal O, and-a negative terminal N.

Referring to Figs. 1A to 1B of the drawings, there-is shown therein a stretch of singletrack railroadbetween the ends of two. passing sidings. It is assumed that the track switches IW and 3W at'the ends-of the passing sidings are poweropersteam the-usual mannerby switch machines under'the control-of the operatorthroughtheC.T.C. system. This control is carried out by-the operation 'oftheswitch levers l SW and 35W ofgFig. 2, which govern switch control relays at the field stations, not shown here. Each of -:-the switches AW and 3W is provided with normal and reverse switch indication relays NWCR and RWCRQshdwnin Figs. 1A and 1E, and the circuits offthe'se indication relays are governed by a contactwhich is controlled inaccordance with the pcsitibn'cr the associated switch so that the contact-establishes the circuit of oneof the indication-"relays when and only-whenthe switch is in' 'the cerre'sponding normal or reverseposition and is "locked'in' that'pos'ition.

Entrance of trafiic moving from left to right, that is,'eastbound, into the stretch, is governed by'g'the head block signals ZRA and ZRB, while entrance of traffic'imoving from right to left, that is, westbound, into the stretchis governed by the head block signals em and 41.13. Movementof eastbound and westbound trainc through the track stretch is'g'overned by the intermediate signalsTESand'. 6W8. The signals may be of any suitableftype and are'here shown as being of the color light type. Each of the head block signals is capable." of displaying either a red or stop indieati'dn 'or'a green or proceed indication, while each of the intermediate signals is capable of displaying either a yellow or caution indication era greener" clear indication. As shown, the

headbloli's'ignalsare continuously lightedwhile track switch, and each of which is provided with a track circuit employing steady energy and including a track relay TR.

The track rails Ia and lb of the single track stretch are divided into a plurality of track sections. As shown, these include a section BT which extends from the detector track section lT at the left-hand or west end of the stretch to the intermediate signals. The portion of the stretch between the intermediate signals and the detector section 3T at its right-hand end is divided into sections 7T, 8T, and ST. The section 8T includes a hand-throw switch 8W which leads to a siding or branch track. The section ST is usually only about 150 feet in length and is provided with a track circuit employing steady energy and including a track relay STR. The switch 8W is normally locked in its normal position and may be moved therefrom when and only when the switch lock 3W1. is energized, while the supply of energy to the winding of the lock 8WL is governed by the track circuit apparatus of the track sections in the main track so that the switch can be unlocked only when it is safe for it to be moved.

Each of the track sections T, 'I'T, and ST is provided with two sets of coded track circuit apparatus, one for each direction of traflic.

As shown, the equipment is in its normal condition in which the head block signals are at stop, and in which the coded track circuit apparatus for both directions of traffic is deenergized so that both intermediate signals are dark.

By reference to Figs. 13 and 1D, it will be seen that the indication control relays 2RFSR and 4LFSR at the ends of the stretch are both released and interrupt the circuits including the channel wires 5a, 6a, 5b and 6b which extend to Fig. 2, so that indication relays 2RBK, 4LBK, ZRFK and ALFK at the office are released and extinguish the block indication lamp 2--4BKE, and also extinguish the traffic direction lamps 2RFE and GLFE.

As the head block signals are at stop, the signal relays ERAHR and ZRBHR in Fig. 1A, and 4LAHR and 4LBHR. in Fig. 1E are released and interrupt the circuits including the wires la and lb so that the signal indication relays ZRHK and 4LI-1K at the ofiice are released with the result that they establish the circuits of the signal indication lamps ZNE and (NE and interrupt the circuits of the other signal indication lamps.

In addition, the track relays ITR and 3TB for the detector track sections are picked up and their repeater relays ITKSR and 3TKSR, are also picked up so they interrupt the circuits which include the channel wires 2a and 2b extending to Fig. 2. Accordingly, the detector section indication relays ITK and STK at the office are released and extinguish the detector section indication lamps ITKE' and 3TKE.

To simplify the drawings, the circuit for relay ITKSR as shown includes only contact IUI of relay lTR and wire I42, and the circuit for relay 3TKSR includes only contact I43 of relay 3TB and Wire hi l, but it is to be understood that the relays TKSR are storage relays which may be arranged like relay TKS of the J ackel patent so that when released, they remain released even though the associated track relay becomes energized until a code is transmitted for energizing the associated indication relay TK.

If the operator wishes to prepare the stretch for trafiic in either direction, he may do so by positioning the signal lever for the signal at the corresponding entrance end of the stretch and 8 transmitting a control code to clear that signal. For purposes of illustration it will be assumed that the operator desires to prepare the stretch for an eastbound train. Inorder to do so he moves the lever 281G, Fig. 2, to the right and presses the associated starting button l-ZSTB to cause the C. T. C. equipment to transmit. a control code to station I2. As lever 2SIG is in its right-hand position the operation of button I-ZSTB establishes a connection from terminal B to channel I5a, and from terminal N to channel l3a, so that, in Fig. 1B energy is supplied to the upper winding of the polar signal control relay ZRI-ISR and its contacts move to their right-hand or reverse position, while the contacts of the signal control relay ZLHSR. are maintained in the normal position as shown.

The circuit of the upper winding of signal control relay 2RHSR includes contacts of the push button IPB. These contacts are biased to a position in which they connect the winding of the relay ZRHSR to the terminals of'the field station unit so that the relay ZRHSR is normally governed through the C. T. C. equipment. When the push button IPB is pressed, energy is supplied from a local source of energy to the upper winding of relay ERHSR. and is of the polarity effective to move the relay contacts to their reverse position. This provides means to reverse the relay locall in the event the C. T. C. system is not functioning.

A second push button 2PB is provided and controls the supply of energy to the lower windings of relays 2RHSR and 2LHSR so that these may be restored to normal locally if desired.

On this movement of the contacts of signal control relay ZRHSR, regardless of whether this movement is effected locally or remotely, its contact Iii, Fig. 1B, interrupts the circuit including wire I 25, for energizing relay ZRASR and establishes a circuit including wire M6 and back contact ll of a block repeating relay ZBPR. so relay ZRASR remains picked up and maintains its own stick circuit. Relay 2RASR is an approach lock ing relay which must be released to enable signal ZRA, or EBB to be cleared and must be picked up to enable switch W to be operated or to enable an opposing signal such as ZLA or ALA to be cleared. Relay ZRASR releases when relay 2BPR picks up, and is picked up over a back contact I04 of the track relay ITR when signal ZRA or 2RB is put to stop by a train entering section IT. Relay ZRASR may also be picked up by restoring the signal control relay 2RHSR to normal when section IT is not occupied, in which case energy is supplied from terminal 3 over wire I45 and back contact I06 to relay 2ASP, which picks up and energizes the time element relay ZTER. After an appropriate time interval of several minutes, relay 2TER closes its contact I29 to complete a pick up circuit for relay ZRASR.

On the movement of the contacts of relay ZRHSR to their reverse position as described above, its contact I2 interrupts the circuit or the code sending relay ZRCSR, to thereby prevent picking up of the contacts of this relay on subsequent operation of the relay SRTPR.

Furthermore, on movement of the contacts of relay 2RI-ISR to their reverse position, contact I4 interrupts the circuit of the restoring relay 2RRR to prevent energization of this relay on subsequent energization of the code detecting relay 2RHR,

On movement of the contacts of relay 2RHSR to their reverse position, contact I5 establishes '9 a circuit: including normal: polar-J contact- IB- of relay 2LHSIh-for supplying energy over back contact I la ofrelaylRHR, Wire 1411' and back contact l8 ofrelay ZRSPAR to actuating impulse generating-relay. ZRS'BR. Accordingly, the contacts of :relay. 2RSPR pick up and its contact I9 establishes theicircuitiof relay ZRSPAR with the result. that its contacts pick up and contact H3 interruptstheucircuit of relay ZRSPR. The relay ZRSER" is snubbed-bya condenser which is of such-size that-the. contacts of relay ZRSPR remain picked up. fora substantial time interval,

'ZRSPR, its contacts pick up and establish the circuit of relay ZRSPARsothat itscontacts pick up, to.. interrupt. the supply of energy to relay 2RSPR; Thereafter the relay ZRSPR remains picked [up .for. approximately 6 seconds and maintains thelsupply of energy to relay ZRSPAR so that; the.-.release.- time ofrelay- ZRSPAR does not start untihrelay ZRSPRreleases, While the relay 2;RS1F AR; doesenot release until about 6 seconds subsequent:- torelease ofrelay ZRSPR.

When the; relays ZRSPAR and ZRSPR are both picked-run, a circuit isestablished for supplying ,energy to the transmitter relay SRCTPR and is traced from terminal B of the local source of energy overv back contact Ell/of relay SRTR, front contact 2| of reIay ZRSPR, front contact22 of relay ZRSPAR, wire M8; back contact 23 of relay ZRCSR, back contact 24 of relay iiRTFPR, back contact. 25 of relay. ZRRPR, back contact 29 of relaylRF-SR, wire [49, front contact 3|- of relay ZRA SR, and frontcontact 32- of relay ITR, to theleft-hand terminal of the winding of relay SRC'IPR. The relay ERCTPR is a polar stick relay the contacts of which are moved to one position. or the other depending on the polarity o-fthe-energy supplied to the relay winding and which remain in their last operatedposition when the supply of energy to the relay winding is interrupted. As shown, the contacts of relay SRCTPR; are in their right-hand or reverse position in which contact 26connects the right-hand I terminal of the relay Winding to terminal C of the source. Accordingly, on completion of the circuit for-connecting terminal B of the source to" the left-hand terminal of the relay winding, energy flows through the relay winding from the left to the right-hand terminal and causes the-relay contacts to move to their left-hand-or normal position. On movement of contact 26 away from its reverse position, the circuit of the relay windingis interrupted but the construction of the relay is such that therelaycontacts continue theirtmovement to their normal position. When the contacts complete their movement to their normal position, the right-hand terminal of therelay winding is connected to terminal B of the source, and, since both terminals of the relay winding are connected to terminal B of the source, energy ceases to flow in the'relay winding and the relay. contacts remain in their normal position. i

10 When the contacts of-relay BRCTPR-are in their normal position, the trackbatteryBLTB is connected acrossthe rails of section BT'in series with the winding of relay GRTR. The relay BRTR, aswell as the other code following-track relays, is of the polar biased neutral type, the

contact of which; picks uponly'in response to energyof-a selected-polarity, and the equipment is arranged so that the polarity of the energy supplied to the relay winding from battery BLTB is of the wrong polarity to pick up-the relay contact.-

The energy supplied from batteryBLTB .to the rails. of section. 5T feeds over back contact 34 of transmitter relay 5LCTP, Fig. 1C, to the winding of track. relayBLTR, and relay SLTR picks upits-I'contact 2:1 to supply-energy to the code following repeater relay 6L'I'P1sothat its contacts pick up and: energyis supplied over its frontcontact 28 to the slow'release front contact repeater relay GLTFEP.

When relay fi-L'I'FP picks up, energyissupplied: to the transmitter relay lRCTP over the circuit which includes back contact 30. of the track relay 'lRTR, front. contact 38 of relay B-L'IFP; and. back contact 39. of a slow. release relay..-6LTBPso the. contact of relay lRC'I'P-picks upand connects track battery 'ILTB across the rails of section. IT in series with the Winding of relay 'IRTR. The energysupplied to the. lefthand-end'of the ,railsof sectionlT. picks upthe track-relay 'ILTR. with the. result that. energy is supplied from terminal B over front contact of ;the, track relayB'lR, front contact. 3%. of relay .ILTR, and front contact 3.7-. of a normal switch indication relay tothetransmitter relay SRC'IfPand its; contactAfl picks up to connect the track battery SLTB across the-rails of section ST" in series with. the winding of track relay SETH.

The energy supplied from. the battery QLTB tothe left-hand end. of the railsof section 9T feeds, over reverse. polar-contacts of the transmitterrelayfiLCTPR, Fig. IE, to the winding of the. track relay, SLTR which picks up its contact 41 so that energy. is supplied over wire I to the repeater relay QLTPR. and its contacts pick up; When the contacts of relay QLTPR. pickup, it energizes the slow release repeatingrelay SLTFPR, and inaddition, energy issupplied from terminal 3 over front contact 42- of relay 3TB, wire...l5.l; normal polarv contact 43 of the signal controlrelay GLHSR, front. contact- 45' of relay BLTPR, and back contact 45 of the code detecting relay 4LHR to the code sendingrelay iLCSR. The. relay lLCSR is of a type the contacts of which are slow topick up andslow to release. As hereinafter explained the supply of energy to relay 4LCSR is maintained for a substantial time interval so-the relay contacts pickup and its. contact 46: establishes the relay stick circuit which includes back contact 45 of relay' lLI-lR. In-addition, when relay lLCSR picks up, itscontact. 4-1: establishes the circuit for the slow release repeater relay 4LCSPR and its contacts pick-up. Furthermore, when relayv 4LCSR picks up, a circuit: is prepared over'its front contact iS for supplyingcoded energy to relay QLCT'P Ron release of relay. 9LTR."

When relay iLCSPR picks up, itscontactinterrupts the.circuit for supplying energy to the restoring relay lRRR so it is certainto remain released. and prevent energization of: relay iRRPRs, While contact 5 l of relay LGSPR interrupts. the circuit fonSupplying energy to the ll indication control relay ALFSR and it is-certain to remain released.

Furthermore, at this time, as relay LLCSPR- is picked up, its contact 52 interrupts the circuit including wire F62 for supplying energy tothe block repeating relay iBPR. and thereby insures that it remains released at this time and prevents interruption of the circuit for the approach locking relay ALASR.

As explained above, when signal control relay ZRHSR is reversed, the relays ZRSPR. and ZRSPAR, Fig. 1A, are picked up and supply energy to relay BRCTPR to move its contacts to their normal position in which energy is supplied from the track battery E-LTB to the rails of section 6T with the result that energy is supplied to each of the other sections in the track stretch. The supply of energy from battery SLTB to the rails of section 6T, as well as from the other track batteries to the rails of the associated sections, is maintained as long as the contacts of relay tRCTPR remain in their lefthand or normal position. In addition, as 'eX- plained above, the relay ZRSPR, when picked up, remains picked up for a substantial time interval, such as 6 seconds, and as long as relay ZRSPR is picked up the circuit for connecting terminal B of the source to the left-hand termi nal of the winding of relay EROTPR is maintained and the contacts of relay SRCTPR remain in their left-hand or normal position.

Accordingly, energy is supplied over the rails of the track stretch for a period substantially equal to the length of the picked-up period of relay 2RSPR, and the track relay SLTR energizes relay BLTPR to establish the circuit for the code sending relay llLC'SR long enough to insure that the relay contacts pick up.

After the expiration of the release time of relay 2RSPR, its contacts release with the result that contact is interrupts the circuit of relay ZRSPAR, but, as explained above, its contacts remain picked up for a substantial time interval and its contact l8 interrupts the circuit of relay ZRSPR. In addition, on release of contact 2| of relay ZRSPR, the previously traced circuit for connecting the left-hand terminal of the winding of relay fiRCTPR to terminal 13 of the source is interrupted and. this terminal of the winding of relay EERCTPR is now connected to terminal C of the source. As the contacts of relay BRCTPR are in their left-hand or normal position, contact connects the right-hand terminal of the relay winding to terminal B ofv the source, and when the left-hand terminal of the relay winding is connected to terminal C of the source, energy flows through the relay winding in the direction to cause the relay contacts to move to their right-hand or reverse position so that contact 26 transfers the right-hand terminal oi the relay winding from terminal B to terminal C of the source, thereby interrupting the flow of energy through the relay 'winding. However, the relay contacts, after movement to their reverse position, remain in that position.

On this movement of the contacts of relay GRCTPR, the circuit for supplying ener'gy'from the battery fiL'I'B to the rails of section ST is interrupted and the relay ERTR is connected across the track rails.

When the supply of energy to the left-hand end of the rails of section ET is interrupted, the relay tLTR, Fig. 1C, releases and its contact 27 interrupts the circuit of the repeater relay BLIP with the result that it releases and its contact 28 interrupts the circuit of the slow release relay BLTFP. Accordingly, relay ELTBP picks up to interrupt at back contact 39 the previously traced circuit for supplying energy to relay 'IRCTP, and relay 'IRCTP releases and interrupts the supply of energy from battery 'ILTB to the rails of section IT. After a short time interval, relay BLTFP releases and its contact 38 additionally interrupts the circuit for supplying energy to the transmitter relay IRCTP. Accordingly, the relay 'lLTR releases and its contact 36 interrupts the circuit for supplying energy to relay QRCTP and its contact All releases to interrupt the circuit for supplying energy from battery BLTB to the rails of section 9T.

After release of relay EBRCTP, the relay BLTR, Fig. 1E, releases and its contact 4| interrupts the circuit of relay QLTPR so that its contacts release with the result that contact 44 interrupts the pick-up circuit for relay AL'CSR, but at this time the relay ALCSR. is energized by current "supplied over its stick circuit so the relay contacts remain picked up after release of relay SLTPR. In addition, on release of relay 9LTPR one of its contacts interrupts the circuit of relay 9LTFPR and it releases.

When relay QLTR, releases, a circuit is completed for supplying coded energy to the transmitter relay QLCTPR and is traced from terminal B over back contact 4| of relay SLTR, over front contact l5 of the codetransmitter 'ISCT, over back contact 53 of a signal relay lRAl-IR which governs the indication displayed'by signal dRA, wire l52, front contact 48 of code sending relay ALCSR, 'over back contact 54 of relay QLTFPR, over back contact 55 of relay ARRPR, over back'contact 59 of relay 4LFSR, wire I53, front contact 58 of relay dLASR, and front contact 57 of relay 3TB, to the left-hand terminal of the Winding of relay SLCI'PR, while at this time the right-hand terminal of the winding of this relay is connected over reverse polar contact 56 of the relay to terminal C of the source. Accordingly, during the picked-up periods of contact 15 of the code transmitter T, energy is supplied to the relay SLCTPR to movethe relay contacts to their normal position in which the right-hand terminal of the winding of the relay is connected to terminal B of the source, thereby interrupting the supply of energy to the relay winding. On subsequent movement of contact 15 of the code transmitter 150T to its released position. and consequent connection of the circuit leading to the left-hand terminal of the windingof relay BLCTPR- to terminal C of the source, energy is supplied to the winding of relay BLCTPR and is of the polarity effective to move the contacts of the relay to their reverse position. It will be seen, therefore, that after release of relay QLTR the transmitter relay SLCTPR is governed by one of the code transmitters lECT or ISBCT, depending upon whether relay dRAl-IR is released or picked up, and the contacts of relay QLCTPR. are operated between their reverse and normal positions at the rate determined by the code transmitter. On movement of the contacts of relay SLC'IPR to their left-hand or normal position, a circuit is established to connect the track battery BRTB across the rails of section 9T in series with the winding of relay QLTR.

On the supply of energy from battery SRTB to the rails of section 9T, this energy feeds over back contact 463 of the transmitter relay QRCTP to the track relay QRTR which picks upits conemanate 1,3 tact. l 5 with; the. ,result that. energy is supplied over front contact 69. of relay, 8TB front con: tactfil of relay tRTR, frontcontactiBZpf, relay 8NWP,.,to .thetransmitter relay 'ILCTP and its contact 53 establishes a circuit for connecting the trachbattery l'RTBracross the railscf section. IT, in series with the track relay lL'IR.

The energy supplied from battery lRTBito the rails, oij'section 1T feeds overback' contact 33 of relay. 'lRCTP to relay YRTR; whichpicks, up its contact Sllso that'energy is supplied'to the code following repeater relay lRTP' and'its contact 64 established the circuit for the slow release repeater relay lRTFP.

During the periods in which the contactsof relay QIJCTPR'are in their right-hand or reverse position. the supply of energy from battery QRTB is interrupted and the relay BRIRreleases so thatcontact ti interrupts the circuitof relay: ELCTP and itreleaseswith the result that contact tt'interrupts the circuit of battery TRTB; Accordingly, relay 'iRTR 'releases and contact 3i! interruptsithe circuit of'relay 'iRTP'so that contactfi ireleases to interrupt the circuit of-relay TRLTFP and establish a circuit including-front contact 65 of relay; 'iRTFP for supplying energy to the-slow release relay FRTBP. The relays lRTFP and TRTBP; as Well as the corresponding 7 similarly designated relays, are snubbedbyrectifiers'so as to be slow enough in releasingto remain picked up during the periods in Whichthe supply ofenergy to the'relay windingsis interrupted Accordingly, these-relays remain picked up as long as the associated track relay-is responding to coded energy.

When relay TRTBP picks up its contact it establishesa circuit for energizing the code transmitter EECT at this location.

When relay" 'iRTFP picks up, its contact- 66 establishes the circuit governed" by (3011133617161 of'relay- 'JRTP for" supplying energy to the pri-. mary- Winding of the decoding transformer 5"-lDT-, and on continued operation of relay lR'I'P its contact iit rectifies energy induced-in a secondarywinding of-the transformer and supplies it te ths-Winding of the slow-release. code detecting-relay t+-lHR and its contacts pick up. Energy induced in a secondary Wll'ldillgrOfitIhIlSiformer 'i-D'If asa' result of operation of rrelay l'R'IP' 'is sums-lied to-through a resonant: decodin unit ltilDU" to a. second ends detecting relay t l'nR" but is of sufii'cient' values tocause relay fit-lDPtito pick; up its contacts.only wherrthe relay 'iR-TP is operated by energy: of. 180 code frequency.

When'relay ERTBP picks up; its contact 691m the: circuit of the lampsof. signal lEs is closed SG'rthflt energyis supplied over-front: contact 10 of: relay @JHR; to the yellow or the green lamp of this signal according as relay 6--'lDRis"r eleased orrpicked up.

When relay, 5 ll-IR picks up, a circuit is completed'for supplying coded energy to transm-itter relay GLCTPand is traced'from back. contact}? ofrelay; tLTR over, front contact H of. relay 'ERTFP, front contact E2 of relay; 'lRTBE- front contact l3 of relay t-'lHR. contact if of the code transmitter !5CT; and back; contacts; of

relay QLIIFP. Accordingly-,- the transmitter, re

contacts-of. relay t-RCTHR. to; the, track. relay,

ERTR and operates it so that during the pickedpiPiZiQ EP Q Q HZaQt I over; wire. 5 10.: t e code f o i g eat r relay fiRTiPRiandits Qnt cts pi k p, a r lease with the. result, that A energy is supplied? over its front contact' iitlitotheslctz release repeater relay tapic fiin i on c s.

W nre ay .fiRTEBRtpick up, its cont ctestablishes,theicircuitscv edi y a onta t f relay ,BRTERf r. supplyin ene y to t c imary windin fli ha decodi ransformer. RDTT Q hationccntinued'ccclef ll w ne p ra on frer y, filt'lffi h er y; s. .indncedin the ransf rmer secondary; wind nsa d is 're0tifid2 y a. onta t ofi elay, ERIE. an i p ied othe ced dates: ine relay ZRHB; to cause that r lay t p k" up ts contacts.

.IILHaQQ IZiQQ-L .whenrelay, BRTEPR k 1 i CQIltaClZMIdiSQQ H IZSW hQWi ad ns fr m the- 1elt+hand. terminal f. he. w n g f ela 611C133 towire. i -8. and; onnec W r 5 0 terminal I ofthe sou ce. o, the su e" hat the, contacts... 0f;v relay, BR TPR'. rema n their riehtmandior ev rseipos n a n n. he cir uitiofjtr lar ETH;

Wh nrelay ZRHRJ' picks p ts con a t, 11 n: terrunts thelpre i usly traced .circuitfor u ply: mg, ener y, over. wire 41. tov the ctuatins.v n?

pulse generating relay ZRSPR' to theigeby prevent picking .un;v f. the ntacts f t is elay. n, B pirat onc fvtherelease. tim of the relay ZB AR and. nsequ nt release; 0f: he a contacts.

In, addition. when relay ZRHR" icks p t conta flzs nt rrunts lthetpickrun ircuit en-the code sending relay 2RCSR' and;. in s11re-, halil?hi r lay,remainsmeleasedtand.docs. nctestahlish t circuit; for, its. repeatin re RC SER;-,

When relay. 2RHR,.picl .s un. ts, cntact. 3.3 1 the circuitnfonsupplyingr energy to therestoring relay. ZBRR 1o sc.c1... 11 atithis time hei ircul ison n at ,ccntact lldf. relay. ZRHSR sa re elay zBRlR-iremainsrel as d, Accordin ly. wh nelay ZRHRl picksup energy is. supplied cv nback -0011? tact 8 5;of,rela;y ZRRRMbaC Sic ntactLBG ofrelay 2RGSER,,. and: front, contact 8.1.- of i relay 231-113. o: the indi ation iflon rql. relay RESR and, its contactsipick up... When relay ZRFSR picks up s ontaetJB remorse. conta ts and rom the: circuit oyer; wire MSL leading. from the left hand terminal of, the. winding, of relay BRG'IBR andconnedtswire. 149,0.ver, front contact. I315. of relay. 6R 1l'ERi to. t r inal C ,of. the, sourc o thereby. insnretha the, contacts ofrelay- RCTIPR rema n, in thc rircverse nositionandmaintain. the circuit-.of 'relaxfifim.. Iriaddition,w enrelay, Z'RFSR piclgs u its contact BIL-Sim Iies ncrey. t0. th ndicat n anr nelificn toien rgize th traits, di a i n e ay ZREK, Fig. 2,,and. itsirorlt. contact 9} connects channel-i Sa to contact 8.9.ofrelay. ZRHR which now onen; ,and'attheoifice, r lay. ZR K p ksup and its contact establishes an obvious. circuit to light, lamp. ZREE. h w. hat he. stretch a been prepared. for; eastbound traffic, but, relay 233K. remains, released. and does, not establish thecincuit of. the block lamn .2.-4BK E.

Betclarine -as,aixiitoft et B t1w be en that when; relay ZBHR, picks. up,, its. front. contact I] establishes the circuit includin back. contact 92 of-relawIRCSRE wire I5 5; front contact 931 of traclg relay; |.1 R-f01' the. detector, track, section LT, baclccontact. 94. of relay. Q'RWCR, and front contact-850 f relay INWCRjfor supplying energy tog thebloclc repeating relay ZBBR so thatits contact: -L- picks-=up a mte mpt-the t ck c r ui of relay ZRASR. and its contacts release' After 1. ner y; upplied? 15 release of relay ZRASR energy is supplied over reverse polar contact of relay ZRl-ISR, wire I46, front contact ll of relay ZBPR, a front contact 99 of the approach locking relay 2LASR, a back contact I of a time element relay ZTER, back contact 95 of relay ZRASR, back contact 91 of relay IRWCR, and front contact 98 of relay INWCR to relay ZRAHR, and its contacts pick up so that contact I00 interrupts the circuit of the red lamp of signal 2RA and establishes the circuit of the green lamp of this signal. The relay 2LASR, a contact of which is included in the circuit of relay 2RAHR, is similar to the approach locking relay ZRASR and is governed over similar circuits, not shown, so as to be picked up when and only when the signals 2LA and ZLB are at stop.

When switch IW occupies its reverse position, relay IRWCR is energized in place of relay INWCR and in this case, relay ZRBHR becomes energized to clear signal ZRB in place of signal 2RA, as will be clear from the drawing. When signal ZRA or ZRB is at clear, terminal B is connected over a front contact of relay ZRAI-IR or ZRBHR to the indication channel 1a to pick up the signal indication relay 2RHK in Fig. 2, and thereby extinguish the lamp ZNE and to light lamp ZRE to inform the operator that the signal has been cleared.

When relay 2RASR releases, its contact 3i connects the wire leading from the left-hand terminal of relay GRCTPR to terminal C of the source to hold the contacts of relay GRCTPR in their reverse position in which they establish the circuit of relay GRTR.

As previously stated, when actuating impulse generating relay ZRSPR releases, its contact l9 interrupts the circuitof relay ZRSPAR and the release time of relay ZRSPAR begins. The release time of this relay is such that its contacts remain picked up for a substantial time interval, and as long as relay 2RSPAR' remains picked up its contact l8 interrupts the circuit of relay ZRSPR. After the expiration of the release time of relay ZRSPAR and consequent closing of its back contact I8, energy is not supplied to relay ZRSPR if coded energy has been received over the track rails as manifested by picking up of contact ll of relay ZRT-IR. Hence, if the. first impulse of actuating code energy has been effective and has caused the code sending relay 4LCSR at the exit end of the stretch to be picked up and thereby cause coded signal control energy to be supplied to the exit end of the stretch so that it is cascaded to the entrance end of the stretch to pick up relay ZBHR, the circuit of relay ZRSPR is interrupted and this relay will remain released. This is proper since there is no reason for the relay to be picked up again. However, if for any reason the first impulse of actuating code energy supplied to the rails of the track stretch has not been efiective, as shown by the fact that relay ZRHR is released at the expiration of the release time of relay 2RSPAR, energy will be supplied to the relay ZRSPR and its contacts will pick up to establish the circuit of relay 'ZRSPAR and thereby cause another impulse of actuating code energy to be supplied to the rails of the track stretch.

This second impulse of actuating code energy will be repeated or cascaded throughout the stretch to the exit end to pick up the track relay SLTR and thus pick up the code sending relay GLCSR to cause coded energy to be supplied to the rails of the track stretch on, termination ama lid

.of the actuating impulse and consequent release or relay QLTR. This coded energy will be repeated to the entrance end of the stretch to pick up the relay ZRHR and prevent subsequent supply of actuating code impulses to the entrance end of the stretch.

As long as relay ZRHSR remains reversed and the relay ZRHR remains released, the cycle of operation of the actuating impulse generating relays ZRSPR and QRSPAR continues so that the relay SRCTPR causes energy to be supplied to the rails of section ET for periods which are separated by periods long enough to enable coded energy supplied at the exit end of the stretch to be cascaded throughout the stretch to the entrance end to pick up relay 2RI-IR and interrupt the cycle of operation of the actuating impulse generating relays.

It will be seen. therefore, that on reversal of relay ZRHSB to clear the entering signal, the actuating impulse generating relays are placed in operation to cause energy to be supplied over the track rails of the stretch from the entrance to the exit end. The cycle of operation of the actuating impulse generating relays is interrupted as soon as the relay ERHR picks to show that further operation of these relays is unnecessary. The actuating impulse generating relays will continue to operate, however, until relay ZRHR picks up to show that their operation is no longer required. This insures that if for any reason the first actuating impulse is not repeated throughout the stretch to the exit end, subsequent actuating impulses will be supplied to the stretch until traiiic is established in the desired direction or until the operator restores the relay ZRHSR to normal to show that this direction of traffic is no longer desired.

As explained above, when coded energy is re ceived at the entrance end of the stretch if the head block signal is cleared, an indication code is sent to the office to show that the signal has been cleared and'to show that trafiic has been established in the desired direction If an eastbound train now accepts signal ZRA and enters the single track stretch, the train first enters the detector section IT and releases track relay ITR so that its contact It'll, Fig. 1A, interrupts the circuit of relay ITKSR and it releases with the result that its contact 32 connects terminal B to the indication channel 2a so that the track indication relay ITK, Fig. 2, picks up to light lamp ITKE in the track diagram. In addition, on release of relay ITKSR, its contact I03 connects terminal C to the circuit which includes the lower windings of signal control relays ZLHSR and ERHSR in series with the result that energy is supplied to the lower winding of relay ZRHSR. to move the relay contacts to their normal position.

In addition, on release of relay ITR, its contact 93, Fig, 1A, interrupts the previously traced circuit for supplying energy to relay 2BPR, and this relay releases, while contact I64 of relay ITR. prepares a pick-up circuit for the approach locking relay ZRASR.

As a result of movement of the contacts of relay ZRHSR to their left-hand or normal position, and also as a result of release of contact ll of relay ZBPR, the circuit of relay ZRAI-Et is interrupted and its contact me releases to interrupt the circuit of the green lamp of signal ZRA and to establish the circuit of the red lamp of this signal. In addition, as a result of movement of contact Asa result of release :of relay position,energy is supplied over contact 10', wire I45, back contact 156 of relay llEtAl-IR, back contact I51 of relay 2RBHR, back contact I84 of relay: ITR to the approach locking relay ZRASR and its contacts pick up so that contact [06 establishes the stick circuit to maintain the relay contacts picked up after section IT is vacated and relay [TR picks up. When relay 2RASR picks up, its back contact 96- additionally interrupts the circuit of relay 2RAHR to insure that it remains-released and holds signal ZRA at stop.

- When relay ITR, releases, its contact 32 0011-,- nects the left-hand terminal of; the windingpf relay GRC'I 'PR-to terminal C of the source and this holds the relay contacts in their reverse posi-.

tion.

. On movement of the contacts of relay ZRHSR to their left-hand or normal position, contact'rl2 in the circuit leading over wire I58 to relay ZRCSR is closed, but atthis time-this circuit is open'at contact l of relay lT-R so the relay 2ROSR remains released. In addition, on this movement of the contacts ofrelay ZRHSR, its'contact M in the circuit of relay ZRRR is closed, but at this time this circuit is open atlcontact lllfi'of relay ITKSR so the relay 2RRR remains released.

Furthermore, on movement of the contacts of relay ZRHSR to their normal position, contact I interrupts the" circuit leading'over wire I41 to relayIZRSPR so thatenergy is not supplied to this relay on subsequent release of relay ZRHR. When the train underconsiderationadvances into'section ET, the track relay GRTR is shunted and remainsreleased so that its contact 2on0 longer establishes the circuit of the repeater relay GRTPR and it releases with the result that its contact 80 interrupts the circuit of relay BRTFPR. and it releases after a short time interval. As a result of cessation of code following operation of relay GRTPR, .energyceases to be supplied through the decoding. transformer ZRDT to the relay 2RHR and its contacts release so that contact il'l'interrupts the pick-up circuit of 'the relay ZRFSR'andestablishes for this'relay a stick circuit which includes its own front con-.-- tact .110; Hence,.the contacts of relay ZRFSR remain picked up.-

As a result of release of relay 2RHR its contact 83"in-the circuit for supplying energy to relay 2RRR is opened and energy will not be supplied to relay ARRR. upon subsequent picking up of the contacts of relay ITKSR. Furthermore, on releaseof relay 2RHR, its contact I! interrupts the circuit including wire l55over which energy is supplied to relay 2BPR to insure that relay .ZBPR remains released; At this time. backcontact all of. relay 2RHR'inthe circuit forsupplying energy over wire 14'! to relay'2RSPRis closed, but at tfi'is time this circuit is open at contact I5 18 ply of energy to the indication channel 1a is inter rupted and relay ZRHK releases to thereby extinguish the lamp ZREand light the lamp 21m to show that signal 2R is now at stop.

When the train vacatessection IT the track relay I'IR picks up so relay ITKSR picks up and disconnects terminal B from the indication chan nel 2a, and relay ITK releases and extinguishes lamp ITKE. 1 I

When relay ITR picks up, the wire leading from the left-hand terminal of the winding of relay SHOT-PR is connected over front contact 32 .of relay iTR, front contact-3l of relay ZRASR, wire l i9,front contact 29 of relay 2RFSR,back contact I36 of relay BRTFPR and normal polar contact I40 of the switch lock control relay 5RWLS to terminal C.

- When the trainadvances into section 1T, the track-relay 'IRTRreleases and remains released so that relay iRTP also releases and remains released with'the result that relays 'IRTFP and FRTBP release. On release of relay 'IRTBP its contact 69 interrupts the circuits of the lamps'of signal IE3 and this signal ceases to display a permissiveindication. In addition, on release of relay 'IRTBP, its contact 16 interrupts the circuit. of the-code transmitter HOT and it ceases to operate. On release of relay 'IRTFP itscontact. 66 interrupts the circuit for supplying energy to the primary winding of the decoding-transformer 6-TDT and energy ceasestov be supplied through this transformer torelaysB-JHR and 6--1DR and they are both released.

As-a result of release of relays 'IRTFP, IRTBP. and 6--'IHR the supply of energy to the trans mitter relay BLCTP is interrupted and it ceases to cause energy to be supplied from the battery GRTB to the rails of section .BT. Accordingly, when the train'vacates section 6T, energy is not supplied over the rails of this section and the relay GRTR, Fig-1A, remains released. 1 I g. Whenthe train under consideration advances into section 8T, thetrack-relay BTR releases and its contact 60 interrupts the circuit for supplying 'of relay ZRHSR so the relay 2RSPR remains released. 1

As explained above, relay 2RFSR is maintained picked upat this time so its contact 90 maintains the supply of energy'to the indication channel 511,

'of relay ZRFSR to 1 the indication channel 6a; "and relayZRBK picksup-so that its :cont'actes- -tablishes an obvious circuit for the lamp 2--4BKE and this lamp :is lighted to show thatlthe'single track s'tretch' isloccupi'ed. Y. 1

ZR AHR the energy to relay ILCTP so it ceases to cause energy to be supplied from battery 'IRTB to the rails of section IT.

When the train'advances into section 9T,the relay SRTR is shunted and remains released and its contact 6| interrupts the circuit of relay lLCTP so that it remains releasedafter section 8T is vacated andrelay BTR picks up. If signal 4RA or 4R3 is now cleared to permit the train to pass out of the stretch; the train may enter section 3T, .therebyreleasing relay 3TR. The signals RA and 4R3 may be controlled in any suitable manner well known'in the art and the details of the control of-these-signals are not necessary to an understanding'of this invention and therefore have been omitted to simplify this disclosure. n Y w When the train enters section 3T and releases track relay 3TB, back contact 51 of relay 3TB connects-the wire leading from the left-hand terminal of the Winding of relay QLCTPR: to terminalC of the source to insure that the contacts ofrelay SLCTPR remain in their reverse position as long as section" 3T is occupied. Accordingly, relay9LCTPR ceases to supply energy from battery BRTB to the rails of section;;; 9'I and when section 9T is vacated relay QRTR. remains released. 1 When the train under consideration enters section 3T and/releases relay 3TH, the relay 3TKSR, Fig 1D," releases and supplies energy 19 to the indication channel'2b, to pick up the relay 31K and light the lamp aT-KE to show that the detector section at this end' or the stretch is occupied.

this time relayA-LESR'is released so energy is not supplie d to the indication channels 52) and Blafahd the indication relaysdLF-K and ALBK remain released; I

When the train vacates section 3T; the track relay 3TB picks up and establishes the circuit of relay 3 IKSBso that it picks up, disconnecting terminal B-from the indication channelib, and relay 3TK-atthe oflice is released to extinguish "the lamp 3TKE.

Referring again to Fig. 1E; itwill be seen that when relay picks up its contact 51 transfers the Wire leading from the left-hand terminal ofthe windingof ;-relay BLCTPR frOm terminal C of-the source tc'contact 58- of-relay cLASR which is picked up at this time. Accordingly, when relay 3TR-picks up, it connects the circuit ofrelay QLCTPR to the previouslytraced circuit includingwires I53 and l-52-and governed by the code transmitter 156T, with the result that relay HLCTPR again operates to cause coded energy to be supplied from the battery QRTB to the rails of-section 9T; Onthe supplyof coded energy to the rails ofsection ST the equipment at the intermediatelocaticns in the track stretch causes coded-energy to be supplied toeach of theiiother sections in the stretch with the result that coded energy'is supplied to relay tRTR and operates its contact to cause the repeater relay BRTPR- to follow coded energy and pick-up relay GRTFPR and to cause energy to be supplied through the decoding transformer ZRDT to relay 231m.

On initial code following operation of relay GR'TP-R, its contact-l l2- establishes a circuitineluding back contact 82 ofrelay-tRl-IR contact H2, normal contact l2-ofcrelay ZRHSR; wire I58 and "contact l01- of relay'- lTR gfor supplying energy torelay 2RSR-.- However, therelay Z-RCSR is of a type the-contacts of which-are slowfin picking up, and the various parts of the equipment are proportioned so that relay ZRHR picks up with the result that its contact Shin-terrupts the ci-rcuitof relay ZRCSR-befcre the contacts'of' -relay '2RSR'-become picked up. Accordingly, at this time relay Z-RCSR remains released and itscontact H3 doesnot establish the circuit of relay ZRCSPR and it remains released.

When relay ZRHRpicks up, its contact 83 establishes the circuit inc-luding cack' contact H4 ofrelay ZRCSPR, contact '83; front contact $08 of relay ITKSR; and normal polar contacts M and 109 of relays ZRHSR and ERWLS for supplyingenergy-to relay 'ZRRR-and its contacts pick up with theresult that contact 85 interrupts the circuit of relay ZRFSRr and establishes the circuit of relay 2RRPR.

"On interruption of the circuit of relaylRFSR, its contacts release, and contact iii? disconnects terminal B fromthe indication channel 5a. Terminal B was disconnected from channel-ta when relay 2-Rl-I R pickedup'and'it follows that relays 2R BKand 2 RFK now release to extinguish the' lamps ZRIEE' and- 2-4BKE.

Referring again-to Fig. lB it will be seen that whenrelay ZRFSR; releases, its-contact 29 dis.- connects the wire I48 leading-*- from the lefthand terminal of the winding Of-relay -SRCFIPR, from contact I Bit-and connects wire: 1-49. to contact of relay IRRPR.v It will be seen that when the restoring-relays 2RRB and 2RR-PR. are

both pickedup, the wire MH -leading from the left-hand terminal of the winding of-relay- SRCTPR is connectedover front contact 25 of relay ZRRPR and'over-front contact I I5 of "relay t-RRR to wire I5fi,-andthence-overback contact- 20 of relayfiRTR to terminal)? of'the source: Accordingly, energy'is supplied to relayEPMIZ'IPR- and causes its contacts toimove to their defthand or normal position inwhich the-batterytLTBis connected across the rails of sectional: The battery BLTB' is connected across the track rails in series with the relay and -the po larity of the energy supplied from the battery through the relay winding is such as to cause the relay=contacts to remain released, thereby.

interrupting the circuit of relay- SRTPR'. Accordingly, relay ERTPR remains released and ceases to cause energy to be: supplied to relay GRTFPR and through the transformer i li-D l to the relay. ZRHRand after a'sho'rttimeinterval the contacts of relays ERTFPR. and ZRHR release with the. result that contact 83 0f relay ZRHR interrupts the circuit of relay man, The relay ZRRR is snubbed by va.condenserwhich is proportioned so. that on interruption of the supply of energy-tov the. relay winding and to. the condenser, the relay contacts are maintained picked upfor alsubstantial time. interval, such as ..-6.- seconds. Accordingly; relayiRRR remains picked. up.- and maintains u the circuitv of f relay ZRRPR. for a substantial timeiinterval after relay ZRI-IR releases; Asslongr as relayZRRR; remains picked upi-the. :contacts.-.ofu relay; ORCTPR are caused to remaintintheir. normal position in which the battery BLTBis-connected across the track rails: Accordingly, energy-is. supplied from therbattery .(iLTB to the rails. ofsection. liI foria considerable time interval. The. energy-supplied tosthe. rails of section (5'1"v feeds toctrack. relay SLTR, Fig.- 10, duringra released period of. the contactscf relay GLCTP. As soon as the -,con-, tact .zl' of relay ELTR picks up itu-mterrupts the circuit. for supplying: coded energy to relay GLCTP so :that-the:contact; ofrelaygfiLCTP is certain to remain released and. maintain. the cit-.- cuit. of relayzGLTR; When relaytLTRapicks up the relay: EELTP: also picks upv and establishes the circuit of relay GLTFP, and duringgareleasedper riocl. of con-tact:3B 'ofsrelay. TR'IR'; energy is supplied over. the .-previously :tracecl circuit including backicontacti .39 rot-relay- GLTBP 130. relay 'IRGTP which picks up its .contacts-to. cause. the battery 'l LTB. to be .-connected.:a'cress. thetrack rails. in seriesswithnrelay;KR/TR; so. that the contact'of relay 'IRFIR. remains released'and maintains the circuit of: relay l'RCilZPs The-energy suppliedfrom'battery ILT-B to the rails of section IT feedsto. relay ILTRzduringsa released period ofgthe contact-bf relay 'ILCTP and picks up relayxlhTRi. :so that. energy is supgplied over. the -.preyiously traced circuit including front contact 35 of relay lLTR to relay BRCTP, which: picks up its contact ,B'itOi-COHDBCt battery SLTBa-cross therailsaof section HT inserieswith thexrelay SRTR; Accordingly,- relay SR'I'R, ;releases andremainsgreleased so that it interrupts the circuit ofv relay .ILCTP: and it; remains released to maintainz'thecireuit for cennectinggrelay ILTR. across therailsof section IT.

The energysuppliedi from battery 9LTB to the rails of; section. Q'R-feedsto track relayjLTR, Fig. '1E,iduring; a period wlncliethe contacts-0t re;- l'a-y .BLCIIPR. .are; in. their: reverse positiom Ac;- cordingly, the contact 4 b of; relaydLIRi Picks-pp. thereby interrupting the circuit over: which thc left-hand terminalof the winding orremy SLCTPR is connected to'terminal B o f the source during a -picked-upp'eriod of the code transmitter which governs-the relay-. -As a'resu1 t-- the contacts of relay 9LCTPR- remain in their reverseposition to maintain the circuit of relay 9LTR the battery 6L'IBto the-railsof section 6T6 This energy picks up relay GLTRtocause energy to be repeated or cascaded through the other sections of the stretch to the right-hand or exit end of the stretch. .The energy: supplied. fromleftto right over the stretch cutssofiuthe supply of'coded en-v ergy. over the. rails. of thezstretchv in .the. opposite directions Accordingly, the slowureleaseandcode. detecting relays I at 1 thexintermediates location; such-as relaysJR'IFP,.. TRTBP. and 6-.lHR,.release. and remaintreleased... .1: .After. the expiration of. the release time of relay ZRRR its .contacts release with theresultithat contactll interruptsthe circuitefor supplying. energy. to. relay..2RRPR, but? this relay is snubbed by.v a condenser which is proportioned so 4 that it maintains therelay contacts pickedup for aisub stantial time interval; such. as. 6 seconds, sub.- sequent to the interruption .of the supply of energy. to therelayz. -Accordingly, .on release of relay ZRRR, the relay. ZRRPRremainspicked upfor a substantial timeinteryal... r

After release. of .relay IRRR. the wire I 49 lead ing from the left-hand terminalOfMthe. winding of relay SRCTPR .is connected: over front'contact 25 of relay ZRRPR. andcover. back contact H5 of relay 2RRR to wire lfilhandback contact I lB of the signal relayiLAI-IRAto contact lll ofethe code transmitter .15 CT.:. .During the picked+up periods of the codetransmitter. the wire I Mlead ing 1130. the. left-hand terminal .of the winding of relay BRCTPR is connected over back contact zll of .relay .GR'IRv to .terminaliB of. the source, while during the relased periods .of thecode transmitter this wireis connected .to terminaliC' of the source. Accordinglyzrelay.BRCTPR is'=now oper ated periodically .to cause.coded.energy to be sup- .pliedirom battery BLTB to the rails of section'BT in place .of steady energy... During thefirst ofi .period in .thescoded energy suppliediirombattery :SLTB to the rails .of section. BTfithe relay SLTR, Fig. 1C, releases and itsrepeaterreIayIZGLTP also releases. v.On release, of relay ELTR' its: back-con;- .tact2l is closed but energy. is notsupplied- -to relay BLCTP. since relay "'IRTFP is released and-its contact H interrupts the circuit of relay: Accordingly, relayBLC'I'P remains released and maintains the circuit of relay BL'IR' so'thatrelay GLTR continues. torespond to coded energy sup"- :plied over therails of section 6T. During the-first .ofi period of this'code; the slow release-relay vBLTBP picks up, closing its contact'l25 te= set the code transmitter l-5CT into operation, and relay 'IRCTP releases due to the opening of back Gj- 'IHRJ -As soon as the contactsof relay-5+Jim; pick up cod'ed energy-is supplied to relay 'IR'CTB over the-circuit which includes back contact ilhg of relay "IRTR front contact 38 of I relay BIJ' I I E front contact' 3'9 of relay- SL'IBP, contact I I 24-0f code transmitter l5C 'IL front 'contact 'l l 9 0i relay 6 'lH-R,' and back contact of relaylRTFPfi Accordinglyj the relay 'IRGTPis now=operated=to5 supply-codedenergy fro'm battery lLTB to the railsof section 'I 'I. l

On the'change in the energy supplied to-section 1T from steady to coded, the relay lLT-R follows coded energy andc'ausescoded energy to beisup plied tofthe' relay llRcTPfso" that it causes codedenergy rails (di section-9T5 I k I I Qnf the change {in the energy SuppIied to the rails of section 9T, the -reIay -QLTR} Fig 1A} re leases-and interrupts the-"circuit of' relay BLG TPR sothatit releases. On movement of the contact 4l of-relay 9LT-R to its released position, no'con ne tion ":isestablished from I I terminal 13 of the source to the left= ha ndterminal-of the winding of relay' 'QLCTPR since the wire 53 I leading from this te'rm'inalof the-relay winding 1 is connected; over back contact '59 of relay' lLFSR, backcontact 5 5 of relay 4RRPR} and -front-'-c0ntact-54' 0f relay QLTFPR to 'terminalC-ofthe -s'ource.-- Therelay- HBTFPR is -'slowenough in='- rel'easing to remain. pickedup-during theoff periods in the coded en ergysupplied overthe'rails of section ar se the reIay' -SLTFPR fpre'vent's operation -ofrelay- QLSCTPR by'codedenergy at this time andinsures tId'at'itS- 'QOntactS Will remainin tliir'riglit-han'd" on reverse position and ma'intain l the circuit of la 2:. I11 1 JI ,1 l-" As' a' result ofcode following operation of relay QLTR, the relay QLTPR. follows code and causes energy'to be supplied throughthe decodingtransformer dLDT to relay ALHR to cause that relay to pick up its contacts with the .result that con"- tact 45 interrupts the circuit ofrelay dLCSR'and its contacts release so thatconta'ct' ll! interrupts the circdit of relay 4LCSP-R; The relay lLCSPR is snubbedjby a condenser which is= proportioned s6 hat the-contacts ofrelay 4LCSPR remain picked up for a'cohsideable time intervaL'such as 20 seconds-subsequent toirelea'se of relay ILCSR and-consequent interruptionof the supply I of e erg'y to the winding of relay 4LCSPR andlthe associated condenser; v v The relay lLI-IR, which causes relea'se of the code sendingfrelay" 41683;, is of a type the con tacts' of whim-are slow to pick up so the .r'elay will not be picked up by'the energy supplied thereto response to a- 'si'ngle movement of the contacts of relay QD'IR- to their p-icked u'pposrtion, but will be pickedup only in response to repeated operation-of the 'conta'cts of relay QLTR. Accordingly',-after relay ALCSR is picked up to cause coded energy to be supplied at the right hand end of the stretch and thereby establish "eastbound'traflic i'nthe stretch, the relay lLCSR will not be released to cutoff the supply ofcoded energy to the track-rails, and'thus interfere-with the established traffic direction in the stretch, as a result of a single movementof the contacts of relay QLTR to I their picked up position, such as -In'ight becaused byan irregular 'track circuit condition or' byvibrationor some other unusual condition.

on" the otherhand, when-coded energyissupplied' over the mug ofthe trackstretch fQrtlie purpose or cuttingoffithesupply of energy to? the stretch and restoring the apparatus to its hero be supplied frbnr battery SLTBI to the mall'ydeenergized conditionr the traehrelay ahm isgrepeatedly- 1 operated: by l the coded energy. and.-

nicksup-relay. 4LHR .to release .:relay;-4LQSR and; disccntinueethe:supplyxofi coded energy to: the.

stretch. The; arrangement of. therapparatns,

therefore, is such. as. to i prevent inadvertent in.

terruption of the supply; of codedenergy; to; the;

' wire 'I 6& to the wire shading: toithe. leftehand.

terminal of the winding of relayfiRGTPR and. connects. this wire, 4%; over backcontact: 24; of relay; BR'IEPR; baclecontacti. 2 3 of reIaX; 2RCSR... wirerl 4B and back .contactizzi of relay 2RSPAR to: terminal CLof. the-source. so that.,-the contacts of relay GRCTPR. are-.moved: to. their right-hand or. reverse position: and remain: inithat positions As a. result, relay. GRCTPR iceasesfto .cause coded energy totbe supplied from.battery fiLTBstmthe. rails of section-6T, and re1ay;.6L'IYR; l';ig 1 G, reeleascs: and remains releasedso-thatrelays-GLTFP.

BLTBRand. B-IHR release and: discontinuethe supplymf'codedenergy, to relay- -TRCTB. Accorde ingly, relay IRCTBtceases to causeeenergysto be supplied from battery. -1LTB;.to therailsoi sec-.- tion IT, and relay 1LTR ceaseseto establish -..the. circuit of. relaytRCfIR. and itremainsreleased so that: energy is no. long-err supplied. from. battery; SL'ITB-tothe rails of section- 9I. Accordingly. re.- lay SLTR releasestand remainsreleasedso\that. relay QLTPR also releases and after a-zshort time interval the relaySLTEPR- releases. whilerelay lLHR-also releases.

When relay QL'IFBR. releases its ontact. 54 transfers the; wire :I 53: 'leadinggfrom the. leftzhand terminal of relay; QLGTPR: to-.. termina1l C of the sourcejo. a connectionileading ovenbacleioontact 48: of relay 4LCSR; wire, 161! ,andiback contact. iii of relay. ALSPAR to terminal Cot these-urea.

.As previously; explained; the release time. of

relaylLCSPR is relatively longandrthe Narious parts of the equipment are proportioned so 1 that relayALCSPR remains picked up until aiterrelay 4LI-IR releases. Accordingly; .contact 1500? relay QLCSBR. continues: to interrupt; the circuit... of relay QRRR. until after this circuitis interrnpted at contact] 22 of-rela-y LI-IR, andathe relay 4RRR is. certain to remain released.atthisztime... In addition. contact: 51.- of: relay .4LCSPR ..contii-1u.es .to interrupt. the pick-up .circuitrof, relay-411F812.

until after thiscircuitdsinterrupteui.byv contact 1.23.:ofrelay-ALHR; so the-relay 4LF SR. .is-;certain to remain released .at .thiStt il'HB:

As lon as. relayfiLCSRR-fis .pickednn c w -tact 52 interruptsthe circuit. includingywire. S2, for relay ABPR, andinsures that'it remains. .releasedzand cannot be picked-up during the period inzwhich relay- 4LI-IR--.is. p ickedup: in response 310 the frequency code1portion; of. the ideenergizing current supplied .over. the .tracks rails. If relay ABPR oould be-picked up,-,it mightresnltin temp orary; unwarranted .display; of; a .permissivein dication by signal 4LA-.or.4LB. but. thecontactpfl of relay. ELCSPR; in the circuit; ofarelay vBF-R prevents I this unintended .clearing of: one of :the signals at this time.

After the expiration. of the. release period, of

relay ALCSPR its 1 contacts' release and theeeguipment is again in substantially. the -.;conditi'on; in

which; it is illustrated in thesdrawings. At-this 24': timethe-coded track circuitequipment isdee'neile; gized-whileithe equipment at the otflce, -Eig."2.

shows that thehead block signals at .both .ends. of the stretch are; at stop, that the. b1cck; .is..

unoccupied and thattraffic-isnot estahlis'hedin. either direction in the stretch.

. The operation oi the equipment when. si nal. ALA or ALB; iscleared to authoriaemovement ofla westbound. train through, the stretch, andin restoring the equipment to its normally, deenere gized condition after; a westbound trai has; vacated I the stretch is substantially: the same-.- as described above in connection with eastbound trafiic and need notbe traced in detail.

Operation oi the equipment to governswz'tch' locks This .system 1 provides; complete control of; the: lock .omazhand-thmw switch at: an intermediate point; in atrackzstretch to I permit-a .train -on:the maingtraclc toentera siding orto permitia train on;the sidingtmenter thev main track.

If. aitrain onrthea main track is, ,tc.-.ent.erl the siding, the train is advancedintosection.851; 1G, thereby releasing. track. relay-.1 3TH; for; the tracksection-which includesthe. switchfl'w; 0n releaseof relay; 8TH. connection: is. established from terminal -;B of "i the source. .QVGI'YUELCREQRQLC?) 35 of relay-18TH: to .one terminal of the winding of: lock 81W L, whileconnection .issestablished from the other. terminal :of the. winding .OfJlOCk SWLto terminaliCrof the sourcecby a contact :iZBi-itthieh is closedzwhen the-door-ofthe cabinet enclosing the switch lQCkLLiS opened. I

When the winding :oflockfiWL is..energized, the: contacts. I3BJ: and? I31 which. are.- governed thereby open thecircuit for the .indication :relay so :that: it; releases and sits contacts .31 5 and 62 prevent transmissionof coded energy: pastLthe switch inpeither. direction.

In addition, on :energization ofthe windingof the. lock; 8WL,; the. locking dog; 12? governed thereby is-moved;out of alignment with thBJaSSQ'r ciated segment so the switchiiW' may now.-b'e reversed;

As soon:.as the hand-throw lever on switch 8W is.operatedathecontacts;l-3'2 and E33 are opened and they remain open as long. as the switch is moved away from. its normal, position. I The-con tacts-i-lj32 J and 1 I33; when open, interruptrthecire cuitofsrelay-iiNWB to prevent itstenergization and thus prevent transmission of; coded :energy past the switch as long astheswitchis reversed. whenrthe train. under consideration enters: the sidingandzvacates section ET; traclrrelay-v 8TB picks; up toainterruptithe supply-of energytto the winding ofthe lock B'WL and itscontacts release. When: theswitch is restored toitsnormalposition andis locked..'in'.that position, the contacts I32 and I33 arezclosed'i so that-energyisagain supplied tothie winding offrelay: 8NW=P andaits contacts; pick; up. The. equipment .is. now. subl- I stantially in-its normal conditionzas shown in Fig.- 1C, and. coded energy supplied. to either end of. thestretchwill be repeatedpastt the switch.

ofiiceasking him to unlock the switch In order tounlockthe switch theswitch lock lever-EW'L,

E-ig. 2,;on the panel-ref the--G.: .T= G. machineis movedto. its right-or its. left-vhand position; ,de-

25 pendingon thedirection in which ;.the.train is proceed afterenteringl the main track. For purposes of illustration it will be assumed that a train 3 is x to ,proceed; eastbound and that the ;operator moves the lever WL to its right-hand 5 position. I .When the lever 5WL is moved to its righthand position and the starting button I-ZSTB operated, it establishes a connection from terminal B to the control channel Ina. Relay l o isnwLs, Fig. 1B, which is connected to termi-'' ,nal O at the back contact I28 ofrelay ZRCSR, .is thereby operated to reverse to close its righthand contacts. .It willbe noted that if theoperator attemptsto reverse relay 5RWLS 'when..l5 relay mean is picked up it W111 be ineffective because both ends of channel I lla will then .be connected to the same terminal B of the source. On the other hand, relay ZRWLS may be restored to normal when relay"2RCSR, is"picked, "up, by operating button I--2S'I,when lever '5WL' fis in its center or leftehan'd. position, since "in this case channel Illa is connected to terminal N at the lever contact." Referring'now to "Fig.

1B it will beseen thatcontact I ofgrelay zfi "S RWLS establishes a circuit including normal polar contact I6 of relay iZLHSR and normal -polar contact I5 of relay 2RI-ISR,contact' I35, fb'ack contact I 31 ofrelay ZRFSR, back contact ll! of relay 2RHR, wire l4l-and back cQntactI'B BO ror'supplying energy to the actuating impulse generating relay ZRSPR. Accordingly, this re- "lay picks up and establishes a circuit for relay 2RSPAR with the-result that these relays op- "erate as described in detail above to cause trans-.35 "mitterrelay GRCTPR to supply energy from battery 'BLTB to the rails of section 6T for a substantial time interval. This energy is repeated or cascaded through the various sections of the stretch as described above to theAO exit end of the stretch and causes relay BLTR, 'Fig. IE, to pick up'and tofcause codesending relay 4LCSR to be energized so that on'termination of the actuating impulse coded energy is supplied tothe right-hand or exit end of the stretch and-is thereafterrepeatedi or cascaded" through the stretch to the entrance end.

When the coded energy is received at the left-hand or entrance vend of zthestretch, the --relay 'ZRHR picks up andits contact I! inter-, 5 .irupts. the circuit of relay ZRSPR so that-it" z -thereafter remains released. ,Inkaddition, when relay '2RHR"DiCkS' up,its iecontactm8'l establishes the pick-up circuit for relayZRFSRand itscontactspick upso that contact H0 prepares the relay stick circuit -which is completed-on subsequent release of contact 81 of relay ZRHR. When contact I! of .-relay 2RI-IR picks up, it

' -'establishes a circuit--over Wire I55 for relay fio IBPR, but this circuit is immediatelyopened I at the back contact H I;3I of relayn2RFsR and e relay ZBPR; isnotoperated. r

..As-.-long as coded energy is receivecl'at the ...left-hand end. of section ET-the relay6RTFPR is-picked up and its front contact I36 connects" the left-hand terminal. of the winding of relay 6RCTP Roverwwire149 300 terminal C of the source.

; After coded energy has been. cascaded. J0 throughout the, stretch so as to be received at {the entrance end and theirelay ZRFSR picksup, ..its .contacts Bland 9|, intheindication channels ,5a and ,.6a are closed. Channel-"5a is g sia d o pi k up re ay RFK and l ght a p of lock 8WL is closed.

26 2RFE to show that the stretch has been pre-- pared for eastbound, traffic. The operator at the central oilice may now inform the train crew at the switch location that the push button 8PB should, be pressed. When this is done, the circuit ofrelay 8NWP is opened and the relay releases sothat' its contact 62 interrupts thecircuit olrelay ILCTP and cuts'bfi transmission of coded energy past the switch from right to left. After release of relay SNWP the relay 9RTR continues, to be operated by coded energysupplied at the right-hand or east issupplied' to .the codc detecting relay SRTBP and its contact I38 in the circuit of the winding After releaseof relay BNWP and consequent cutting. off of the supply of energy to relay ILCTP, the supply of coded energy to the portion of .the stretch at the left or west of the switch 8W is cut offjand relays ZRHR. and

.BRTFPR at the left-hand end of the stretch .become released. release of a relay 2RHR,

relay 2RFSR ismaintained' picked up by'energy supplied. overits stick circuit so its contact I 31 interrupts the circuit governed by contact I35 of relay 5RWLS fonsupplying energy over wire I41 to the relay ZRSPR and relay ZRSPR'is not energized on release of contact I1 of relay 2RI-IR.

After release of relay GRTFPR, the wire I43v leading from 'the left-hand terminal of the winding of transmitter "relay' BR'CTPR iS connected to contact II 1 ofthe code transmitter 15CT over a .circuitwhich includes front contact 29 of relay2RFSR; back contact I36 of relay GRTFPR, reversepolar contact I40 of relay SRWLS, wire I60, and back contact H6 of relay ZLAI-IR. 'According'ly, he transmitter relay YSRCTPR, now operates to cause coded energy to be supplied from battery BLTBto the rails of section 6T, This energy is repeated intosection 1T bythe equipment at the intermediate signal location,' Fi g. 1B, sothat-the relay ILTR is operated by'coded energy. During the picked-up periods of. relay ILTR', energy is supplied over back contact'3! of relay 8NWP to the slowrelease relay 'ILTEP, and duringthe 1 released periods of contact 36 of relay ILTR energylis suppliedto the code detecting relay 'ILTBP and its contact MI in the circuit of the windingof switch lock 8WL is closed. The circuit of the winding of lock 8WL is now complete and its lock now releases theswitch so thatit may be moved. When the train under consideration entersthe stretch, the track relay 8TB, releases and its contacts 35 and'BO interrupt the circuits for supplying energy to the code detecting relays with the result that they release but at this timethelock' 8WL is energized by current supplied over back contact 35 of relay 8TB.

As explained above, it is assumed that the train Will proceed eastbound so that the train advances intosection. ST and holds relay QRTR' released; Whense'ction 8T is vacated, relay ,BTR

, picks upand'whh the switch 8W is restoredto fits normal'position and is locked in that posil tion,'itherelay 8NWP again becomes energized.

After the switch'hasbeen reversed, one of the traincrew phones'theoperator at the central o'f- 27 .iice and'he restores -the switchlockleverfiWL, 'Fig 2, to'its normalposition. Acontrol co'd'e'is fn'ow sent to field station 'l2 which 'causesthe f contacts of relayBRWLS to' be restored to their Inormal position. I D1; this movement 101"- the contacts of relay --5RLWLS its contact I48 interrupts the previous- 'ly traced circuit for supplying coded energy to -transmitter relay iiRCTPR and connects wire 1 49 extending to'the lefthand terminalof the Win flling of this relay to terminal C of the source with the result thatthe contacts of the relay move to their'right hand or reverse position and remain inxt'hat position, thereby interrupting the circuit of battery tLTBand connecting the 'reiay'en'rn across the railsiofsection'6T. 7

When the supply of coded energy to the en- Jt'rance end of the stretch is cut 'off,"'the supply ,or coded-energy tothe other portions of the stretch in the rear of the train is cut oil and ILTR, Fig. 1C, releases and remains released and Lino. longer establishes the circuit for Qrelay j'QRCTP- so'th'at it releases and establishes'thecir- .icuitof relay QR'IR. v v I Whenthe train under considerationgpas'ses out ,or the stretch, coded energysupplied at the'rightfhand or east en'd of the stretch feeds to'relay and operates it -so that it causes relay J'ILCTP to supplyro'ded energy to the 'railsof rsection 7T. As a result the equipment "at the intermediate r signallocation operates as pre- ,v viouslydescribed to cause coded energy to be supplied to the rails of section'fiT and this energy operates relay 'GRTR, to cause relays,

fiRTFPRand-ZRI-IR-to become picked up.

Nhenrelay 2RHR picks up its contact ri'l'inter- ,rupts-the stick circuit for relay '2RFSR, while contact 83 of relay .ZRHR establishes the previouslytraced circuit .ior supplying energy tolre- ,lay VZBRR andiits contact 85 picks up toin'ter- -rupt-thecircuitof r'elay'2R-FSR andito establish the circuitof relay IRRPR.

-- When relays ZRRR andLZRRPR are picked up the y control the transmitter.relay-fiRCTPR to cause :it to supply deenergiz ing current to the arails of section 6T, this current consisting of a long impulse ofsteady energy followed by a simi- .lar-per-iod'of coded energy. I I M As a result of release oi reIayYZRFSl-R, its con" :tactsSB and Qi open andcauserelaysZR-FK and QQRBK to-release tothereby extinguish the lamps ;.=2RFE and-24BKE-.

The deenergizing currentsupplied to the rails -ofsection is cascaded-to the right-hand or i exit end of the stretch Whereit operates traci: wrelay-lLT R-tocause release of the code sending relaydLCSRandthereby restore the equipment ,ctodts normally deenergized conditionion' termination of the .deenergizing cur-rent.

Although I have herein shown and described only a .few .iorms of railway signaling system embodyingimy invention, it isun'derstood that various changes and modifications maybe" made therein within the scope of the appended claims without departing from the spirit andscope 7 my invention.

Having thus described my invention, what I claim is:

1. In .a normally deenergized coded track circuit signaling system, in combination, a stretch of railroad track having at each end a signal governing entrance of traflic into the stretch, code I transmitting means for each end ofsaid track ystretch effective when rendered active tosupply energy to the rails of said track stretch, a

28 code following 5 track" relay for each *end'pf sa'i'd track stretchefiectively connected acrossth'e trackrails whenthe associated'code transmititing means'is not "supplying'energy to the-rails,

.ing up each of said. code detecting relays onlylin response to the reception of signalcontrolenergy as manifested byaplurality of movemen'tsof the contacts of the associated'track relay between their two positions within a predeter- ,25 mined time interval and for thereaitermaintainingthe vrelay picke ad up as long asthe tracker;- lay responds periodically to such signal control energy,-a manually operable signal control relay-ateach-end of-the stretch effective when operated to cause the associatedsignal .to clear -upon picking up of the associated code'fdetecting ,relay,and-actuating mcans-ateach end ofthe stretch-effective when theassociatedsignal control'relay is operated andthe code detect-ingrelay responsive to operation lof the associated track relay is released iorvcausing the-associsponds "to signal control energy it e picks *up the associated 'c'o'de detecting relay without :operating the associated code sending'rel'ay.

2. In a nor-mally' deenergizedcode'd track 'cirsuit-signalingsystem, in combination, *a stretch of railroad track havingat 'ea/ch end'a's'ignal governing entrance of traffic intothe stretch,

code transmitting means for each end of -said track stretch effectivewhen'rendered active to supply energy totherailsofsa'id track stretch,

-'track rails when the associated code transmitting means is not supplying energy tether-ails,

to detect whether or'not energy'is being supplied thereto from the oppositeendof the stretchga code sending relay-at each' end-of said stretch effective when operatedtoren'der'the associated code transmitting means active "provided the "associated trackrelayis released to' supply'ipulses of signal control energy? periodically to "the rails of the stretch at a predeterminedcode rate-each code sending relay being of the slow pick-up 'type "responsive to energization ofthe associated track relay'only when'such trackrelay'is steadi'ly energizedfor a period substantially longer than the longest1pu1se of signal'controlenergy 'supplied'to said track relay, each-code sen-ding r lay h ving a slow acting repeater which"is

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