US2390010A - Railway signaling apparatus - Google Patents

Description

Filed June 30, 1944 2 Sheets-Sheet l H. A. TALBERT ET AL RAILWAY SIGNALING APPARATUS INVENTORS HenPyA. Talbep and ZWEI/Z ATTORNEY Nov. 27, 1945.

Nov. 27, 1945. H. A. TALBERT ET Al.

RAILWAY SIGNALING APPARATUS Filed June 30, 1944 2 Sheets-Sheet 2 b lnuwmmm klim,

Henpy Cmw aplef. 131mm/v THEIR ATTORNEY Patented Nov. 27, 1,945

RAILWAY SIGNALING APPARATUS Henry A. Talhert, Churchill. and Crawford E. Staples, Pittsburgh, Pa., assignors to'The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application June 30, 1944, Serial No. 542,936

11 Claims.

Our invention relates to railway signaling apparatus for use on stretches of track through which trailic may move in either direction, but only in one direction at one time.

In Letters Patent of the United States No. 2,344,333 issued March 14, 1944 to James J. Van Horn, there is shown a signaling system for use on stretches of single track between two passing sidings. That system is arranged so that when the single track stretch is vacant and is not prepared for traffic in either direction, steady energy is supplied to the section at one end of the single track stretch and is cascaded or repeated through all of the other sections to the other end of the track stretch where it energizes traffic locking means to indicate lthat the single track stretch is not occupied.

When it is desired to condition the single track stretch to permit `movement of a train therethrough, the supply of steady energy to the track stretch is cut off, while coded energy is suppliedv to the section at the exit end of the stretch with the result that coded energy is supplied to the remaining sections in the stretch and causes the Wayside signals, including the signal at the entrance to the stretch, to display permissive in'- dications.

'T he operation of the system shown in the Van Horn patent is such that coded energy is supplied to the rails of the track sections whenand only when movement of a train through the track stretch is authorized, While steady energy is supplied to the rails of the track sections when trains are `not permitted to enter the single track stretch.

It is desired to' permit signal maintainers or others to operate small motor cars in the track stretch `to transport themselves and their equipment. As usually constructed, the Wheels and axles of these cars are insulated so that these cars donot shunt the track circuits and therefore do not control the Wayside signals so trains inthe track stretch are not infomed of the presence of the motor cars.

It is desired to provide means to inform operators of the motor cars of traino conditions in the track stretch so that these cars can be removed from the track rails when movement of a train through the stretch is anticipated. In order to provide this information on the motor cars it has been proposed to equip the motor cars with indication lamps con'trolledby relays connected acrossv the track rails so as to be operated by energy from thetrack circuits. When a car is traversing a stretch in which trailic movements are not authorized. the steady energy supplied to the track rails causes the relay on thecar to steadily establish the circuit of the indication lamp on the car, but if the car is traversing a stretch in which traino movements are authorized, the coded energ'y supplied to the trackrails causes the relay on the car to intermittently establish the circuit of the indication lamp on the car and this nashing lamp is notice to the operator of the car to expect a train and "to remove the car from the track.

In order for the indications on the motor cars to be complete it is necessary for the track circuits for the tracksections in the portions of the main track beside passing sidings, and in the passing sidings if they are provided with track circuits, to be arranged to operate in substantially the same manner as the track circuits for the track sections in the single track stretch, that is, so that coded or steady energy is supplied toV thel section rails according as `traine is or is not authorized to move through the track section.

It is an object of our invention to provide improved track circuit apparatus for use in the track sections beside a passing siding, or in passing sidings equipped with track'circuits, of a track stretch equippedwith signaling apparatus of the type described.

A further `object of the invention is to provide f improved apparatus of the type described whichV is arranged so as to be controlled by the remote control Vapparatus governing traic in the track stretch without exceeding the normal capacity of the remote control apparatus. l

Other objects of the invention and features of novelty will be apparent from the following description taken in connection with the accompanying drawings.

We shall describe one form of railway signaling apparatus embodying our invention and shall then point out the novel features thereof in claims.

In practicing our invention we provide a track section with two sets of coded track circuit apparatus, one for each direction of trallc'. When the signals at both ends `of this section are manually held at stop, -steady energy is supplied to the section rails at one end of the section and picks up the track relay at the other end of the section to lindicate that the section is not occupied.

When it lis desired to prepare the section for traffic in one direction, 'the C. TL C. system or other remote control apparatus is operated to cut off the supply oi steadyenergy to the section rails, thereby releasing the track relay at the other end of the section and causing the equipment at that end of the section tooperate to supply coded energy to the section rails. This energy operatesl the track relay of the track circuit for thev selected direction of tra'c to` clear the associated signal, while at this time the track circuit apparatus for the other direction of tra-nic is operated by feed-back energy 4and Vthus maintains the indication of the fact that the section is not occupied. When a train enters the section, the supply of feed-back energy over the section rails is cut off, thereby causing the track circuit apparatus to operate to indicate that the section is occupied, while steady energy is supplied to the section rails behind the train, and when the section is vacated, this energy picks up the track relay at the exit end of the section to thereby cut off the supply of coded energy to the section rails and indicate that the section has been vacated.

When it is desired to prepare the section for traffic in the opposite direction, the C. T. C. or remote control system is operated to cut oi the supply of steady energy to the section rails and to cause coded energy to be substituted therefor to thereby operate the track relay of the track circuit for the selected direction of traffic to clear the associated signal. On movement of a train through the section, the apparatus of the track circuit -for the other direction of traffic is arranged to be operated by feed-back energy when the section is vacated and master code energy is again supplied over the section rails, while operation of this track circuit apparatus by feed-back which trafc may move in either direction The portion of the track stretch shown includes a passing siding PS, the left-hand or west end of which is connected with the main track by a switch IW, and the right-hand or east end of which is connected with the main track by a switch 3W.

The track rails I and 2 of the main track are divided by insulated joints 3 into a plurality of track sections including a detector section IT which includes the switch IW, a detector section 3T which includes the switch 3W, and a section 2T which includes the portion of the main track beside the passing siding PS.

The single track portions of the track stretch at each side of the passing siding are likewise di- 'F vided into track sections and these portions are equipped with signaling apparatus of the type shown in Letters Patent of the United States No. 2,344,333 to James J. Van Horn.

This invention is directed particularly to the track circuits for section 2T and to the means for controlling the signals 2RA and SLA which govern traffic in section 2T, and is not concerned with the construction and operation of the signaling system for the single track portions except insofar as the apparatus of this invention is intended to operate in conjunction with the apparatus for the single track portions.

The detector sections IT and 3T are each provided with a track circuit including a track relay TR which is energized by current supplied from a track battery over the section rails.

Each switch has associated therewith a polarized indication relay WP to which is supplied energy of normal or reverse polarity according as the switch occupies its normal or its reverse position, while each switch indication relay WP controls a normal switch indication relay NWP and a reverse switch indication relay RWP.

The track section 2T is provided with two sets of coded track circuit apparatus, one for each direction of traffic. As shown, there is a code following track relay ZETR located at the west end of section 2T and operated by energy supplied from a battery ZETB at the east end of the section, while a code following track relay ZWTR at the east end of section 2T is operated by energy supplied from a battery ZWTB at the west end of the section.

The relays ZETR and 2 WTR are of the polar biased neutral type and their contacts pick up only when energy flows through their windings in the direction indicated by the arrows, while coding relays ZWCTM and ZECTM control the supply of energy from the track batteries through the track relay windings to the track rails.

The signaling apparatus for section 2T is governed by remote control apparatus, such as a C. T. C. system, which controls relays ZRHSR and WFSR at the west end of section 2T and relay llLl-ISR at the east end of section 2T.

The equipment at each end of section 2T includes a source of direct current, the positive and negative terminals of which are d'esignated B and C, respectively.

The equipment is shown in its normal condition in which traiiic in neither direction is authorized to enter section 2T. At this time, the contacts of relay 2RHSR occupy their left-hand or normal positions, while the contacts of relays WFSR and IlLHSR occupy their right-hand or reverse positions, and steady energy is supplied to relay ZWCTM over the circuit which includes front contact I0`of relay I TR, front contact II of relay ZRASR, normal polar contact I4 of relay ZRHSR, front contact I5 of relay INW'P, and reverse polar contact I6 of relay WFSR. Accordingly, contact I8 of relay ZWCTM is picked up and establishes the circuit for supplying steady energy from battery 2WTB through the winding of relay ZETR to the rails of section 2T.

At this time, relay ZETR is steadily released so relays 2RAH and ZRAD are released, while as the contacts of relay ZRHSR'are in their lefthand or normal positions, energy is supplied to the red or stop lamp R of signal ZRA.

As hereinafter explained, relay ZECTM is released at this time and its contact 2l] establishes the circuit of relay ZWTR so that energy supplied from battery ZWTB to the rails of section 2T feeds to relay 2WTR and picks up its contacts. As relay ZWTR is picked up, energy is supplied over its front contact 2| to relay TWTRP which is a code following repeater of relay ZWTR. Accordingly, rel-ay 2WTRP is picked up and its contact 23 permits energy to be supplied over the relay stick circuit including back contact 24 of relay ZECTM and front contact 22 of relay EFSR, while contact 25 of relay 2WTRP establishes the circuit of slow release relay FSA and relay FSA is picked up.

At this time, relay 4LHSPR is released so that its contact 26 interrupts the circuit of the primary winding of decoding transformer WDT.

As relay 2WTRP is steadily energized, and as the circuit of the primary winding of transformer WD'I' is interrupted, the relays 2LH and 2LD are released.

As relay FSA is picked up, its contact 48 interrupts the pick-up circuit of relay EFSR, while contact 2| of relay ZWTR interrupts the stick circuit of relay EFSR so it is released and its contact 22 interrupts the stick circuit for relay 2WTRP.

As the contacts of relay 4LHSR are in their rightLhand position, contact `33 establishes the circuit of the red or stop lamp R of signal `ALA.

At -this time, the relay WSR is energized by current supplied over its pick-up circuit which includes lfrontcontact 30 of relay dLASR, front contact 3| of relay 3TR, and front contact 32 of relay iFSA, while energy is also supplied to relay WSR'over the stick circuit `which includes its own Tfront contact 34 and front contact 30 of relay4LASR. `As relay WSR is picked up, its contact 35 permits energy to be supplied -to relay EFSR, and its contact 36 permits energy to -be supplied to relay'2ECTM.

relayZWTR issteadily picked up, its contact 2| interrupts thecircuitof relay 4LHSPR and'its contacts are released so that contact 4U interrupts connection from one terminal of secondary winding 4| of transformer WDT to terminal C?` and thus prevents supply of energy from this winding to relay ZECTM.

The approach locking stick relay llLASR is provided-to prevent movement of switch 3W or clearing of signals 4LA and 4LB except when conditions are proper. The details of the control 'of reIayALASR are not a part of this invention and this relay `may be governed in any manner well knownin the art, and one way in vwhich therelay may be governed is shown in Letters Patent of the `United States No. 2,093,170 of Ronald A,

McCann, or in Letters Patent of the United States .Y

No. 2,117,691 of Earl M, Allen et al. The relay 4LASR, "when picked up, causes both of the signals governing movement of westbound traflic acrossswitch` 3W to display stop indications, and

must be released before either of these signals 5 can display a permissive indication.

Similarly, the relay-2RASR is provided t0 prevent movement of-the switch I-W or clearing of the lsignals ZRA and ZRB governing movement of eastbound traffic Aacross the switch IW except When-conditions are proper. The relay ZRASR when Apicked up causes both of the signals governing'movement of westbound traic across the switch |Wto displaystop indications, and must be released before either of these signals can display apermissive indication.

rilis'exp'lained in-the above identified patent to Allen et al. the circuits of ltre locking relays RASR and LASR are controlled by route relays soV that the locking relays release when and only when the route sought to be established is complete.

`The C. T. C; system'employed `for communication between the oiiice and stations may be of the type lshown in application for Letters Patent of the United States, Serial No. 496,907 of Arthur-P. Jackel, filed July 3l, 1943, for Remote control systems. The details of the construction and peration of the C. T. C. system are not a part oi this -invention vexcept insofar as the apparatus of this invention is intended to operate in conjunction with the C; T, C. system.

AFor purposes of this application it is sufficient to s'tate'that'the C. T. C. system provides Ameans operable atthe will of the operator to energize the relay 'SER1-ISR with current of either polarity and to energize relay ALI-ISR with current of either polarity, -while the system also provides means under the control `of the operator for supplying energy to v`the upper winding of relay WFSR to thereby move the contact of this relay to its lefthand or normal position. A terminal of the winding ofrelay IWFSR'is connected to a terminal |50 on the coding unit of the C. T. C. system at *the eld station, and this terminal is identifled by the same reference numeral asis employed in the Jackel application referred to above to identify the corresponding terminal.

This system provides means vfor causing the C. T. C. system to operate totransmit to the cnice an indication of occupancy of section 2T. When relay FSA releases, its contact i2 establishes-a connection from a source of current toterminal |42 of the station unit, this terminal being identied by the same reference numeral as is employed for the corresponding terminal in Fig. 2C of the above-mentioned Jackel application.

From the foregoing, it will be seen that when the signals governing entrance of Vtrains into section 2T at both ends or the section are at stop steady energy is supplied to the section rails. Accordingly, if at this time a motor car equipped with indication means governed by energy in the track circuit is present in section 2T, the indica-`| tion means will operate to indicate that trains are not authorized to enter this section.

Operation of equipment to authorize an eastbound train to enter section 2T 'In order to prepare section 2T for eastbound traiiic the operator manipulates the C. T. C'. system to move .the contacts of relay ZRHSR to their right-hand or reverse positions. On this movement ofthe contacts of relay ZRI-ISR. contact 44 interrupts'one circuit for supplying energy to the red'lamp Rl of signal 2BA andestablishes the circuit controlled by contacts of relays INWP and`2RASR for supplying energyto'the lampsy of signal 2BA.

On movement of the contacts of relayZRl-ISR to 'their reverse positions the relay 2BA-SR releasesto permit energy'to be supplied to the lamps of signal 2BA over the circuitscontrolled by relays ITR, ZRl-I and .2RD. The means by which relay ZRASR is controlled byrelayZRHSR isnot a part of this invention, andthe circuits of relay ZRASR may be arranged in any appropriate manner well known in the art, as forv example as shown in the` above-mentioned patents to Ronald A. McCann, and toEarl M. Allen et al.

In addition, on this movement of the contacts of relay ERI-ISR, its Contact Iii interrupts the circuit traced above for supplyingsteady energy to relay ZWCTM and connects relay QWCTM to a secondary winding of the decoding transformer EDT. Accordingly, contact i8 of relay ZWCTM Y releases and cuts ofi the supply of energy from battery 2WTB to the rails of section 2T so relay ZWTR releases and its contact 2| interrupts the pick-up circuit of relay ZWTRP. At this time the stick circuit of'relay ZWTRP is interrupted by contact 22 of relay EFSR so relay ZWTRP releases when its pick-up circuit is interrupted.

' On release of relay 2W1R` its contact 2| es tablishes connection from terminal B over back Contact 5E] of relay EFSR, to one terminal of the winding of relay LHSPR: However, at thistime, contact 65 of relay'llLI-ISR interruptsconnection from the other terminal of the winding of relay ALI-ISPRto terminal C so relaytLHSlBl?. remains released and its contact 66 maintains connection from terminal C to one terminalof the winding of relay EFSR.

On release of relay ZWTRP, its contact 25 interrupts the circuit of relay FSA and it releases so that energy is supplied to relay EFSR over its pick-up circuit which includes back contact 48 of relay FSA, front contact 35 of relay WSR, winding of relay EFSR, and back contact 66 of relay lf-LHSPR. Accordingly, thecontacts of -relay EFSR. pick up and energy is supplied to the relay over its stick circuit which includes back Contact 2l of relay ZWTR, front contact 50 of relay EFSR, front contact 35 of relay WSR, and back contact 56 of relay ALHSPR, while contact l) of relay EFSR interrupts the circuit of relay 4LHSPR to thereby insure that relay 4LHSPR remains released.

When relay EFSR picks up, its contact 52 establishes a circuit for supplying to the relay 2ECTM coded energy of 75 or 180 code frequency depending on the position of a contact 54 which is governed in accordance with the aspect displayed by signal 4RA so as to be released when signal 4RA displays its stop indication and to be picked up when signal GRA displays either its caution or its clear indication. After picking up of relay EFSR, if contact 54 is released7 energy is supplied to relay 2ECTM over the circuit which includes back contact 53 of relay ZWTR, a Contact of code transmitter '|5CT, contact 54, front contact 52 of relay EFSR, front Contact 36 of relay WSR, and front contact 55 of relay STR, while if contact 54 is picked up, energy is supplied from terminal B over a contact of code transmitter ISBCT, front contact 54, front contact 52 of relay EFSR, front contact 36 of relay WSR, and front contact 55 of relay STR to relay 2ECTM.

The coded energy supplied to relay 2ECTM operates it so that coded energy is supplied from battery ZETB to the rails of section 2T and this energy feeds to relay ZETR over back contact I8 of relay ZWCTM and operates relay 2ETR so that energy is supplied through the decoding transformer EDT to relay ZRH, and is also supplied to relay 2RD through the resonant rectifier unit |80DU if relay ZETR is operated by energy of 180 code frequency.

During the picked-up periods of relay 2ETR, energy is supplied over its front contact 5| to the lower winding of relay WFSR, and this energy serves to maintain contact I6 of relay WFSR in its reverse position as shown.

At this time, therefore, energy is supplied over reverse polar contact 44 of relay ZRHSR, front contact 5B of relay INWP, back contact 51 of relay ZRASR, front contact 58 of relay ITR, front contact 59 of relay ZRH, and contact 60 of relay ZRD to the green or the yellow lamp of signal 2RA depending on whether contact 50 of relay 2RD is picked up or released.

In addition, as a result of operation of relay 2ETR energy is supplied from a secondary winding of transformer EDT to relay ZWCTM. The relay 2WCTM is of a type the contact of which picks up only when energy of a selected polarity is supplied to the relay winding, while the Various parts of the equipment are arranged so that energy of this polarity is supplied from transformer EDT to the relay ZWCTM on release of the contacts of relay ZETR. The impulses of energy supplied from transformer EDT to relay ZWCTM pick up the contacts of relay ZWCTM momentarily and keep them picked up for a period somewhat shorter than the shortest off period in the coded energy supplied to relay ZETR.

When contact I8 of relay ZWCTM picks up, an impulse of feed-back energy is supplied from battery 2WTB th'rough the winding o-f relay ZETR to the rails of section 2T and this energy feeds over back contact 2E! of relay 2ECTM to relay 2WTR and picks up its contacts so that its contact 2| establishes the circuit of relay ZWTRP. When relay ZWTRP picks up, energy is supplied to the relay over its stick circuit which includes front contact 22 of relay EFSR, front contact 23 of relay ZWTRP, and back contact 24 of relay 2ECTM, and this energy serves to maintain the contacts of relay 2W'I'RP picked up throughout the entire released period of the contacts of relay 2ECTM.

When relay 2WTRP picks up, its contact 25 establishes the circuit of relay FSA and its contact 42 interrupts the circuit leading to terminal |42 of the C. T. C, field station unit and the C. T. C. equipment operates to indicate that section 2T is not occupied.

When relay 2WTR picks up, its contact 53 interrupts the circuit for supplying coded energy of '75 code frequency to relay 2ECTM. Mowever, the impulses of energy supplied to relay ZWTR when relay ZWCTM is operated by energy from the transformer EDT are of such' limited duration that relay 2WTB. releases and reestablishes the circuit for supplying energy to relay 2ECTM before closing of the contact of the code transmitter controlling the supply of energy of '75 code frequency to relay 2ECTM.

When relay ZWTR releases, its contact 2| interrupts the pick-up circuit of relay ZWTRP but this relay is held picked up by energy supplied over its stick circuit until relay 2ECTM picks up.

If at this time energy of 180 code frequency is being supplied to relay 2ECTM, the circuit for supplying energy to relay 2ECTM is established as soon as the contact of code transmitter |CT closes regardless of whether or not the contacts of relay 2WTBl have released. Under these conditio-ns, when relay 2ECTM picks up, its contact 24 interrupts the stick circuit for relay ZWTRP, while its Contact 2D interrupts the. circuit connecting relay 2WTB across the section rails and establishes the circuit for supplying energy from battery ZETB through the relay ZWTR to the section rails. The energy supplied from battery ZETB through the winding of relay ZWTR causes the relay contacts to release, if they are not already released, so that contact 2| interrupts the pick-up circuit for relay ZWTRP and its contacts release.

At this time, therefore, relay 2ECTM is operated by coded energy and causes impulses of master code to be supplied to the rails of section 2T, while relay ZWCTM operates as a feed-back impulse relay to supply an impulse of feed-back energy to the section rails during each 01T period in the master code. The impulses 0f feed-back energy pick up the relay 2WTR momentarily so that relay ZWTRP is picked up and remains picked up until relay 2ECTM picks vup to supply another impulse of master code to the section rails, whereupon relay ZWTRP releases.

As relay FSA is picked up, its contact 48 interrupts the pick-up circuit of relay EFSR but relay EFSR is maintained picked up by energy supplied over its stick circuit during the released periods of contact 2| of relay 2WTB.

As relay 4LHSPR is released, its Contact 25 interrupts the circuit of the primary winding of transformer WDT so energy is not supplied through transformer WDT to relays 2LD and 2LH and they remain released.

When an eastbound train accepts signal ZRA and enters section |T, the track relay ITR releases and its contact 58 interrupts the circuit controlled by relays ZRH and ZRD for supplying energy to the lamps of signal 2RA and establishes a circuit for supplying energy to the red lamp R of the signal.

In addition, on release of relay ITR, its contact B3 interrupts the circuit of' sloW releasing relay ITRP and establishes a circuit including front contact Sli of relay ITRP :for vsupplying to the loWer windinor of relay ZRH'SR energy eiective lto move the contacts of relay ERI-TSR to their lefthand or normal positions s o that contact 44 establishes the circuit of the red lamp R of signal ERA, While contact it establishes a circuit including back contact i i `of relay ZRASR for supplying energy from transformer EDT to relay `Z'WC'IM.

When relay lTR releases and the contacts Aof relay ZRHSR move to their left-hand or normal positions, a pick-up circuit, not shown, is established for relay ZRASR and its-contacts, pick up,

On release of relay ETR, its Vcontact il) interrupts the circuit for supplying steady energy to relay ZWCTM and establishes a circuit for connecting relay ZWCTM -to a secondary Winding of transformer EDT after relay ZRASR picks up .and the contacts of relay ZRHSR move to their normal positions. This circuit is traced from a .terminal of the transformer secondary winding over back contact I of relay lTR, front Contact .9i of relay 2RASR, normal polar contact l A1 of relay ZRHSR, front Contact Iii of relay INWP, and reverse polar contact |601" relay WFSR to the relay ZWCTM, and insures that relay 2WCTM .will continue to operate to supply impulses of feed-back energy to the Yrails of section 2T until the train advances into section 2T.

When the train advances into section ET, the track relay EETR. is shunted and relays ERH and ZRD release, while relay .ZWCTM ceases to 4supply impulses of feed-back energy to the rails of section 2T so relay ZWTR remains released and :does not establish the -circuit of relay ZWTRP. Accordingly, relay Zilli/"TRP remains released and .does not establish the circuit of relay FSA and it yreleases so that lits contact iii establishes the circuit for supplying energy to terminal M2 of the C. T. C. system station unit to thereby cause the C. T. C. system to transmit to thepfce an indication of the fact that section 2T is occupied.

At this time relay EFSR is maintained picked up by energy supplied over its stick circuit which includes its own front contact 53 and back contact 2l of relay RWTH, as Well as by energy supplied over hack contact t8 of relay FSA.

On release of relay FSA, its contact 32 interrupts the pick-up circuit for relay WSR, but relay W SR is maintained picked up by energy supplied over its stick circuit.

If, at this time, signal ARA is displaying a permissive indication, the train may advance into the single track stretch, and when it enters section track relay STR releases and its Contact 55 interrupts the circuit -fo-r supplying coded energy to relay EECTM, While contact 3l of relay `3THJ additienally interrupts the pick-up circuit of relay WSR.

On release of relay means not shown, causes the signal `@RA to display its stop indication and contact 54 causes coded energy subse- `quently supplied to relay ZECTM to be of 75 code `frequency, While signal SRA continues to display its stop indication as long as the adjacent section in advance of section is occupi-ed.

When the train vacates section ITy track relay i-TR picks up and steady energy is supplied to relay Zvi/'CTM over front contact l Ei of relay lTR, iront Contact Il of relay ZRASR, normal polar contact iii of relay ZRHSR, iront contact i of relay INWP, and reverse polar contact It .relay VtTFSR. Accordingly, ,contact i3 of relay ZWCTM is picked up so that steady energy is supunav,

plied from battery `ilW'IB to the rails of section 2T. When the train vacates section 2T, this steady energy feeds to relay WTR and picks up its contacts so that contact 53 interrupts the circuit for supplying coded energy of 75 code frequency to relay ZECTM, While contact 2l interrupts the stick circuit of relay EFSR and establishes the circuit of relay Zvi/TR? sorthat relay ZWTRP picks up and its Contact 25 establishes the circuit of relay FSA and it picks up With the result that contact 5.8 interrupts the pick-up circuit ci relay EFSR. Accordingly, relay ZECTM remains released and maintains the circuit of relay ZW'R, While relay EFSR releases s-o that its contact 5l! additionally interrupts the relay stick circuit, While Acontact 52 of relay EFSR interrupts the circuit for supplying coded energy to the relay ZECTM.

On the supply of `energy to relay ZWTRP and resultant picking up of relay FSA, its contact 42 interrupts the supply of Venergy to terminal M2 of the C. T. C. system station unit and .thus causes the C. T. C. system to transmit to the oiilce an indication yof the fact that section 2T has been vacated.

if, while section 2T is occupied, the operator vWishes to permit another eastbound train to enter `section ZT as soon as it is vacated by the Vrst train, the C. T. C. system is operated to move the contact le of relay vZRT-ISR to its reverse position to thereby cut oil the supply of steady energy to relay EWCTM and it remains released so that steady energy is not supplied to .the rails of sectionZT,

Accordingly, when the first train vacates section 2T, the equipment at the east end of the section supplies coded energy to the section railsand this energy operates track relay ETR to clear signal 2BA while relay ZWCTM functions as an impulse relay to supply feed-back energy to the section rails and cause the equipment at the exit end of the section to indicate that the section has been vacated.

If, after signal 2BA has been cleared but before a train has entered section 2T, it is desired to put the signal tostop, the C. T. C'. sys- ,tem is operated to move the contacts of relay ZRHSR to their left-hand positions so that contact 'dll of relay R'l-ISR establishes the circuit of the red or stop lamp R of vsignal ZRA. As a result of this movement of the contacts Iof relay 21H-ISR, a circuit, not shown, isestablished to pick up relay ZRASR after a predetermined time interval, such as four minutes. When relay ERASR picks up, steady energy is supplied to relay ZWCTM and it is picked up to interrupt the Circuit of relay 2ETR and to cause steady energy to be supplied to the rails of section 2T. This energy keeps relay ZWTR picked up so that relay EFSR releases and its contact 52 cuts 01T the supply of coded energy to the relay 'EECTM and thus to the rails of section 2T.

Operation of equipment to authorize a westbound train to enter section 2T In order to prepare section 2T for Westbound trailic, the operator manipulates the C. T. C. system to cause the station apparatus at the right-hand end of section 2T to supply energy to relay .aLl-ISR to move its contacts to their lefthand or normal position, While the station apparatus at the left-hand end of section 2T is caused to establish connection from terminal B of the source of current to terminal |50 of the station unit and thus cause to be supplied to relay WFSR energy effective to move its contact I6 to its lefthand or normal position.

On this movement of the contact I6 of relay WFSR, the supply of steady energy to relay ZWCTM is cut off and coded energy is supplied thereto over the circuit which includes a contact of a code transmitter IBGCT or CT, depending on the position of contact B8 which is governed in accordance with the indication displayed by signal ZLA, front contact 69 of relay ITR, front contact 'I0 of relay 2RASR, and normal polar contact I6 of relay WFSR. Accordingly, relay 2WCTM operates to supply coded energy from battery 2WTB to the rails of section 2T.

On movement of contact 65 of relay ALI-ISR to its left-hand or normal position, connection is established from terminal C over front contact 61 of relay 3NWP to the right-hand terminal of the Winding of relay ALHSPR, so that as soon as the contacts of relay 2WTR release, energy is supplied to relay 4LHSPR over the circuit including back contact 2l of relay ZWTR, back contact 50 of relay EFSR, winding of relay ALHSPR, front contact 61 of relay 3NWP, and normal polar contact 65 of relay 4LIISR. The energy supplied t0 relay dLHSPR picks up its contacts so that Contact 66 interrupts connection from terminal C to the right-hand terminal of the winding of relay EFSR to thereby insure that relay EFSR remains released, while contact 66 establishes connection from terminal C to the right-hand terminal of the winding of relay 4LHSPR to thereby keep the relay energized after contact 65 of relay 4LHSR is moved to its right-hand or reverse position.

During code following operation of the relay 2WTB, the supply of energy to relay dLHSPR is interrupted during the picked-up periods of contact 2| of relay 2WTB., but the relay BLHSPR is slow enough in releasing to remain picked up in the periods during which the supply of energy to the relay winding is interrupted.

When relay dLl-ISPR picks up, its Contact 26 establishes the circuit for supplying energy to the primary winding of transformer WDT so that on coding operation of relay ZWTRP energy is supplied through the transformer to relay 2LH and also to relay 2LD if relay 2WTRP is operated at the 180 code rate.

In addition, on picking up of relay ALI-ISPR, its contact establishes connection from one terminal of secondary winding 4l of transformer WDT to the reverse polar Contact 65 of relay 4LHSR so that, when contact 65 of relay ILHSR is returned to its reverse position, energy may be supplied from secondary winding 4l of transformer WDT to relay 2ECTM.

At this time, relay EFSR is released and its contact 22 interrupts the stick circuit for relay ZWTRP so that relay 2WTRP operates as a direct repeater of relay ZWTR.

On movement of the contacts of relay SLI-ISR to their left-hand or normal position, contact 33 interrupts the circuit of the red lamp R of signal BLA and estabishes the circuit controlled by relays 3NWP, EFSR, dLASR, 2LH and 2LD for supplying energy to the lamps of signal ALA, while on this movement of the contacts of relay ALHSR the relay 4LASR releases. The means for controlling relay'llLASR is not a part of this invention and this relay may be controlled as explained in the above-identified patents to McCann and to Allen et al.

On release of relay ALASR, its contact 30 interrupts the circuit of relay WSR and it releases with the result that its contact 34 additionally interrupts the relay stick circuit, while its contact 35 additionally interrupts the circuit of relay EFSR. to insure that it remains released.

On release vof relay 4LASR, energy is supplied over normal polar contact 33 of relay LHSR, front contact 12 of relay 3NWP, back contact 28 of relay EFSR, back contact 64 of relay 4LASR, front contact 'Il of relay STR, front contact 13 of relay 2LH, and contact 14 of relay 2LD to the yellow or the green lamp of signal 4LA.

As a result of code following operation of relay ZWTRP energy is induced in the secondary winding 4I of transformer WDT. However, relay WSR is released and its contact 36 interrupts the circuit for supplying energy from winding 4l of transformer WDT to relay ZECTM, while this circuit is additionally interrupted by contact 65 of relay llLHSR so relay ZECTM remains released and does not operate to supply impulses of feedback energy to the rails of section 2T. Accordingly, relay 2ETR remains released and its contact 5| does not establish the circuit of the lower winding of relay WFSR and its contact I6 remains in its normal position to maintain the circuit for supplying coded energy to relay ZWCTM.

If a westbound train now accepts the permissive indication displayed by signal GLA and advances into section 3T, track relay ETR will release so that its contact 'H interrupts the circuits controlled by relays 2LD and 2LH for supplying energy to the lamps of signal ILA and establishes a circuit for supplying energy to the red lamp R of this signal.

Also, on release of relay 3TH., its contact 16 interrupts the circuit of slow releasing relay STRP and establishes a, circuit including front contact 11 of relay STRP for supplying to relay 1LT-ISR energy effective to move the relay contacts to their right-hand or reverse position. On release of relay 3TR and movement of the contacts of relay dLHSR to their reverse position, the relay ALASR is picked up by a circuit, not shown, while relay LASR remains picked up after relay STR picks up.

On movement of the contacts of relay LI-ISR to their right-hand or reverse position, contact 65 interrupts connection from terminal C to a terminal of the winding of relay iLHSPR, but contact 66 of relay 4LHSPR maintains connection from terminal C to the relay winding so the relay contacts remain picked up.

On movement of contact 65 of relay dLHSR to its right-hand or reverse position, connection is established from terminal C over front contact 40 of relay 4LHSPR to one terminal of the winding 4| of transformer WDT, but at this time the supply of energy from the transformer to relay ZECTM is prevented because of release of contact 36 of relay WSR or contact 55 of relay 3TH, While as soon as the train enters section 2T the relay 2WTB, ceases to follow code and impulses of energy are no longer induced in secondary winding 4| of transformer WDT and energy therefore is not supplied from this winding to relay ZECTM. Accordingly, at this time, relay ZECTM remains released and maintains the circuit of relay 2WTBl and does not cause energy to be supplied from battery ZETB to the rails of section 2T.

In addition, on movement of the contacts of relay ALHSR to their right-hand or reverse position, contact 33 establishes the circuit of the red lamp R of signal 4LA.

When the train advances into section 2T, the

track relay -2WTR ceases to follow .code so .relay 2WTRP remains released :and relay FSA releases and its contact 42 establishes the circuit leading to terminal |42 of the C. T. C. system station unit and this system transmits to the oice an indication of the fact that section 2T `is occupied. In addition, on `release of relay FSA, its contact 32 interrupts the pick-up circuit of relay WSR so that relay WSR remains .released after section 3T is vacated and relay 'ETR picks up.

When relay ZWTRP ceases to follow code, energy ceases to be supplied through transformer WDT `to relays yZLI-l and 2LD `and they release..

lf signal `2]'.lA has been cleared, the train may advance into the single track portion at the left of section 2T. When the train enters section iT, track .relay ITR releases and itscontact t!! Vinterrupts the circuit `traced above for `supplying coded energy to relay ZWCTM so coded energy ceases to be supplied to the rails of section 2T. At this time, `signal ZLA is caused :to display its stop indication so contact S8 `establishes V.the circuit for supplying energy of '75 code frequency to relay ZWCTM .after section IT is vacated. and relay ITR picks up.

When the train `vacates sections 2T and IT, the relay ZWCTM is operated by energy of 'Z5 code frequency `and causes coded energy to be supplied tothe rails of section 2T. This energy picks up relay ZWTR so that it establishes the circuit of relay ZWTRP and it picks up and its Contact .Z5 establishes the circuit of relay FSA. Accordingly, relay FSA picks up so that its contact 42 interrupts the circuit leading to terminal I i2 of the C. T. C. system station unit and the C. T. C. 4system operates to transmit to the office an indication of the fact that section 2T has been vacated.

When relay FSA picks up, energy is supplied .to relay WSR over its` pick-up circuit which includes front .contact 38 of relay eLASRfront contact 3| of relay STR, and front contact 32 of relay FSA, so the relay WSR picks up .and its contact 34 .establishes a stick circuit to maintain the relay picked up as long as relayY @LA-SR is picked up.

When relay ZWTR picks up, its contact 2l in.- terrupts the circuit of relay LHSPR but this relay is slow in releasing so that its contacts remain picked up .during the picked-up periods of relay ZWTR, while relay QWTR is operated by coded energy. Accordingly, front contact (l lof relay BLHSPR remains closed so that energy is supplied to the relay Winding during the released periods of contact 2| of relay EWTR, while contact Iii) of relay fiLHSPlEty maintains connection from a terminal` of the Winding li of transformer WDT over reverse polar contact 65 of relay ILILI-ISR to terminal C, and contact '2t of relay ALHSPR maintains the circuit `of the primary Winding of transformer WBT.

During the iirst ofi interval in the coded energy supplied from battery ZWTB to the rails of section 2T, relays 'ZWTR and ZWTRP release andthere is induced in the secondary winding il Aof transformer WDT an impulse of energy `of the polarity effective to pick up the contacts of relay ZECTM momentarily. This energy is supplied to relay ZECTM over the circuit which is traced from terminal C over reverse polar contact -55 of relay LI-ISR, iront contact @is of relay iLHSPR, Winding t! of transformer WBT2 back contact -52 of relay EFSR, front `cfmtact Se of relay WSR, front contact 55 of relay STR, and `Winding of relay ZECTM to terminal C.

When relay ZECTM .picks up, an impulse `of feedback energy is supplied from battery ZETB to the rails of section 2T and this energy feeds over back Contact I8 of relay ZWCTM to relay ZETR and picks up its contacts so that contact 5i establishes the circuit for supplying energy to the lower winding of relay WFSR. This energy moves the contact it of relay WFSR from its normal to its reverse position to thereby cut off the supply of coded energy to relay ZWCTM and to establish the circuit for supplying steady energy thereto. This circuit includes front con.- .tact t9 of relay ITR, front contact I! of relay ERASE, normal polar contact i 4 or" relay ERHSR, front contact l5 of relay INWP, and reverse polar Contact lli of relay WFSR.

Accordingly, relay ZWCTM is steadily picked up and causes steady energy to be supplied from battery ZWTB to the rails 0i section 2T. This energy feeds over back contact 203 of relay ZECTM to relay ZWTR and keeps it picked up so that relay 2li/'TRP is steadily picked up to maintain the circuit 0f relay FSA, while as relay ZWTR is steadily picked up, its contact 2i interrupts Vthe circuit of the relay LHSPR.

As relay -2WTRP is steadily picked up, -energy is not supplied from transformer WDT to relay 2ECTM and it remains released and connects relay ZWTR across the rails of section 2T.

After a short time interval, relay LlLHSPR releases and its contact 2c interrupts the circuit of the primary Winding of transformer WDT, and there is induced in secondary winding li an impulse of energy of the polarity effective to pick up the contacts of relay ZECTM. However, on

vrelease of relay IiLi-ISPR, its contact lic interrupts the circuit for supplying energy from transformer Winding lli to the relay ZECTM so relay ZECTM remains released and maintains the circuit of relay 2WTR.

On release 0f relay LHSPR, its contact 66 additionally interrupts the circuit o-f the relay Winding,

From the foregoing it will be seen that when section 2T is conditioned for Westbound traino, the supply of steady energy to the section rails is cut off and coded energy is supplied to the section rails at the West or exit end of the section.

'This energy operates the equipment at the east or entrance end of the section to control signal @LA and to keep relay FSA picked up and canse the C. T. C. system to indicate that section 2T is not occupied.

Since coded energy is supplied to the rails :ci

`section 2T when the section is prepared for Westbound traiiic, the equipment on a motor car present in the track section when the section is prepared for Westbound trahie will .operate to. indicate that trains are authorized `to enter the section.

l/Vhen a Westbound train enters the section, relay FSA releases and causes the C. T, C. system to report that the .section is occupied, while coded energy continues to be supplied to the west vend oi' the section; Entrance of a Westbound: train into section 3T conditions the .equipment at the east end of section 2T to operate to supply feedback energy to the section rails when section 2T is vacated and 'master code .energy is aga-in supplied over the section rails. The feed-back .en-

ergy supplied to the rails oi section 2T causes the equipment at the west end of the section to cut 01T the supply of coded `energy to the section ,rails and to supply steady energy thereto and thus restore the equipment to its normal inactive condition.

If, while section 2T is occupied, the operator wishes to authorize another westbound train to enter the section as soon as it is vacated by the first train, the C. T, C. system is operated to move the contacts of relay SLHSR to their left-hand or normal positions. On this movement of the contacts of relay lLHSR, the relay @LASR releases and its contact 3!) interrupts the circuit of relay WSR so that relay WSR remains released if the rst train vacates section 2T before the second train enters the section. As relay WSR is released, its contact 36 interrupts the circuit for supplying energy from winding 4I of transformer WDT to relay ZECTM. Furthermore, when contact 65 of relay ELI-ISR is in its left-hand position, it interrupts connection from terminal C over front contact 49 of relay dLHSPR to a terminal of secondary winding 4l of transformer WDT and therefore additionally prevents supply of energy from this winding to relay ZECTM. Accordingly, when the first train vacates section 2T and relay ZWTR is operated by coded energy supplied over the section rails, energy is not supplied from winding 4I of transformer WDT to relay ZECTM and it does not operate to supply impulses of feed-back energy from battery EETB to the rails of section 2T and relay rETR remains released and its contact 5I does not establish the circuit of the lower winding of relay WFSR. As a result, contact I5 of relay WFSR remains in its left-hand position to maintain the circuit for supplying coded energy to relay ZWCTM so coded energy continues to be supplied to the rails of section 2T and operates the equipment at the east end f the section to clear signal @LA and authorize the second westbound train to enter section 2T.

Operation of equipment for section 2T when a switch is reversed The equipment for section 2T is arranged to operate in an appropriate manner when a switch at either end of the section is reversed.

When switch IW is reversed to connect the passing siding with the single track portion at the left of section IT, the relay INWP releases and relay IRWP is picked up. On release of relay INWP, its contact I establishes a circuit independent of relay ZRHSR for supplying steady energy to relay ZWCTM. This permits the relay ZRHSR to be employed at these times to cause signal ZRB to be controlled by traffic conditions in the passing siding, and on movement of the contacts of relay ZRHSR to their reverse positions, steady energy continues to be supplied to relay ZWCTM.

On release of relay INWP, its contact 56 interrupts the circuit controlled by relays ZRASR, ITR, 2RH and 2RD for supplying energy to the lamps of signal 2RA, and establishes a circuit for supplying energy to the red lamp R of this signal to thereby maintain the display of the stop indication by signal ZRA as long as the switch IW is reversed.

The equipment operates to permit section 2T to be prepared for westbound traic while switch IW is reversed. As stated above, when switch IW is reversed, relay INWP is released and relay IRWP is picked up. When relay INWP is released, steady energy is supplied over its back contact I5 and reverse polar contact I6 of relay WFSR to relay ZWCTM so that steady energy is supplied from battery ZWTB to the rails of section 2T.

If it is desired to prepare section 2T for westbound traiiic, the C. T. C. equipment is operated to supply energy to relays WFSR and ALHSR to move their contacts to their left-hand or normal positions. On this movement of the contact I6 of relay WFSR, the supply of steady energy to relay ZWCTM is out olf, while energy of 75 code frequency is supplied thereto over the circuit which includes a contact of code transmitter 'I5CT, back contact 68, front contact 8I of relay IRWP, and normal polar contact I6 of relay WFSR. Accordingly, the relay 2WCTM operates to cause energy of 75 code frequency to be supplied to the rails of section 2T, while the equipment at the right-hand or east end `of the section operates as explained above so Athat signal IILA displays its yellow or caution indication.

The circuit for supplying coded energy to relay ZWCTM at this time is independent of the track relay ITR so that the supply of coded energy to the relay ZWCTM, and thus to the rails of section 2T, is not aiected by occupancy of section IT by a train moving between the passing siding and the main track.

Similarly, the circuit for supplying coded energy to relay ZWCTM at this time is independent of the relay ZRASR so that coded energy continues to be supplied to relay 2WCTM if relay ZRASR is released to clear signal 2RB and authorize an eastbound train to move from the main track to the passing siding.

If a westbound train accepts the permissive indication displayed by signal ILA and enters section 2T, the supply of coded energy over the section rails is cut 01T so the signal 4LA displays its stop indication, while the equipment at the east end of section 2T is conditioned to supply feedback energy to the section rails when the section is vacated.

If, after section 2T -is occupied, the switch IW is restored to its normal position, the relay IRWP releases and its contacts 8| interrupts the circuit traced above for supplying coded energy to the relay ZWCTM. However, before the switch IW can be moved, the relays ZRASR and ITR must be picked up, and on release of relay IRWP coded energy is supplied to relay ZWCTM over the circuit including front Contact B9 of relay ITR and iront contact 'I0 of relay ZRASR,

When signal 2LA is cleared and the train in section 2T vacates the section, the equipment for section 2T operates as explained above to cause steady energy to be supplied to relay ZWCTM and thus cause steady energy to be supplied to the rails of section 2T.

The equipment for section 2T is also arranged to operate in an appropriate manner when switch 3W is reversed. When switch 3W is reversed, relay SNWP is released and relay SRWP is picked up. When relay 3NWP is released, its Contact 'I2 interrupts the circuit over which energy may be supplied to the yellow and green lamps of signal ILA and establishes a circuit over which energy is supplied to the red lamp R of signal 4LA after movement of contact 33 of relay IILHSR to its normal position.

When relay 3WRP is picked up, its contacts 85 and 86 establish circuits for energizing relay WSR, while contact 83 establishes a circuit for supplying energy to relay ZECTM and contact 81 establishes connection from terminal C to the front contact 40 of relay IILHSPR.

The relay WSR is normally energized by cur rent supplied over its stick circuit which includes its own front contact 34 and front contact 30 of relay ALASR, and as relay 4LASR must be picked up before switch 3W can be moved, the relay WSR will normally be picked up when the switch 3W is moved to its reverse position. After movement of the switch 3W to its reverse position, energy may be supplied to relay WSR over the circuit including frontv contact 85 of relay 3RWP and front contact 34 of relay WSR, while energy may also be supplied to relay WSR over front contact 85 of relay SRWP, front Contact 8S of relay 3RWP, front contact 3l of relay 3TR, and front Contact 34 of relay WSR, Accordingly, if, while switch 3W is reversed, relay ALASR is released to clear signal 4RB, or if section 3T is occupied by a train moving between the passing siding and the main track, .the relay WSR is maintained energized by current supplied over the circuits established on picking up of relay 3RWP and front contact 35 of relay WSR is closed to permit energy tobe supplied to relay EFSR.

If, while switch 3W is reversed, it is desired to condition section 2T for eastbound traffic, the C. T. C. system is operated to move the contacts of relay ZRHSR to their right-hand or reverse position so that contact Ill of relay ZRHSR interrupts the supply of steady energy to the relay ZWCTM and connects relay ZWCTM to a secondary winding of transformer EDT. As explained above, this results in release of relays ZWTR and ZWTRP and picking up of relay EFSR so that energy of '75 code frequency issupplied to relay ZECTM over the circuit which yincludes back contact 53 of relay ZWTR, a Contact of code transmitter 15CT, contact 54, front contact 52 of relay EFSR, front Contact 36 of relay WSR, andV f' front co-ntact 55 of relay STR. At this time, contact 63 of relay SRWP is closed and establishes a connection shunting contact 55 of relay STR and contact 35 of relay WSR in the circuit of relay ZECTM. This insures that the supply of coded energy to relay ZECTM will be maintained if relay STR is released due to occupancy of section 3T by a train moving between the passing siding PS and the single track stretch at the right of section 3T.

lOn the supply of coded energy to relay ZECTM it operates to cause coded energy to be supplied from battery 2ETB to the rails of section 2T and thus cause the equioment at the left-hand end of section 2T to establish the circuit of the yellow lamp Y of signal ZRA, while relay ZWCTM operates to cause impulses of feed-back energy to be supplied to the rails of section 2T. This feedback energy operates relay ZWTR so that relay ZWTRP causes energy to be supplied to relay FSA.

If an eastbound train now accepts the permissive indication. displayed by signal ZRA and enters section 2T, the supply of coded energy over the section rails is cut oil-and signal ZRA is caused to display its stop indication, while the equipment at the entrance to section 2T causes steady energy to be supplied to relay 2WCTM so tbat steady energy is supplied to the rails of section 2T.

When section 2T is occupied, the supp-ly of feed-back energy over the section rails is cut off and relay FSA releases to cause the C. T. C. system to indicate that the section is occupied. In addition, when section 2T is occupied, relay WTR is released so its contact 2l. establishes the stick circuit for relay EFSR which includes itsl own iront contact 5c and iront contact 35 of relay WSR and relay EFSR remains picked up to main.-

tain the supply of coded energy to relay EECTM.

The switch 3W must be restored to its normal position before the eastbound train in section 2T can vacate the section, and when the switch 3W is moved to its normal position the relay SRWP releases and relay SNWP picks up. As relay @LASR must be picked up before the switch 3W can be moved, contact 3U of relay QLASR establishes the stick circuit for relay WSR and it remains Picked up after release of relay SRWP.

If signal 4RA is now cleared and the train in section 2T vacates the section the steady energy supplied to the rails of section 2T at the west end of the section feeds to relay ZWTR and picks up its contacts to prevent supply of energy to relay ZECTM, and to interrupt the stick circuit for relay EFSR and it thereupon releases. When relay ZWTR picks up, it establishes the circuit of relay ZWTRP and it picks up relay FSA so that contact 42 interrupts the circuit leading to terminal |42 and the C. T. C. system indicates that section 2T has been vacated.

The equipment at the east end of section 2T is arranged to insure proper operation of the track circuit apparatus for section 2T if the switch 3W is reversed at a time when section 2T'is occupied by a westbound train. When section 2T is conditioned for westbound trahie, the contact IS of relay WFSR occupies its left-hand position in which it establishes the circuit for supplying coded energy to relayl ZWCTM, while the contacts of relay ILHSR are moved to their left-hand position to permit signal LA to display a permissive indication and to pick up relay ALHSPR,

On movement of a westbound train through section 3T, the contacts of relay IILHSR are returned to their right-hand or reverse positions by energy supplied over the circuit controlled by relays 3TR and 3TRP so that contact 65 establishes connection from terminal C over front contact 40 of relay GLHSPR to one terminal of the secondary winding il of transformer WDT. At this tima-relay llLHSPR is maintained picked up by energy supplied over its stick circuit which includes its own front contact B6.

If the switch 3W is now reversed, the relay 3NWP releases and relay BRWP picks up. If it is desired to permit a second or following westbound train to enter the passing siding, the C. T. C. equipment may be manipulated to move the contacts of relay ALHSR t0 their left-hand or normal positions to cause signal LB to display a permissive indication.

After the switch 3W has been reversed and relay ALHSR has been operated to clear signal 4LB, but before the second train enters section 3T, the train in section 2T may vacate the section.

As explained above, when a westbound train vacates section 2T. the relay ZWCTM is operated by coded energy supplied over normal polar contact I6 of relay WFSR. and coded energy is supplied to the rails of section 2T. This energy 010-' crates relay ZWTR so that relay ZWTRP operates and causes impulses of energy to be induced u in the secondary windings of transformer WDT.

At this time. energy is supplied from secondary winding il of transformer WDT to relay EECTM over the circuit which is traced from terminal C over front contact 87 of relay SRWP, front contact d!) of relay llLHSPR, winding fil, back contact 52 of relay EFSR, front contact S3 of relay 3RWP, and winding of relay ZECTM to terminal C. Accordingly, relay ZECTM operates to supply an impulse of feed-back energy to the rails of section 2T during an off period in the master code supplied to the section rails and this feed-back energy picks up the contacts of relay RETR so that energy is supplied over front contact to relay WFSR to move the contact i6 of relay WFSR to its right-hand position and cut off the supply of coded energy to relay ZWCTM and to establish the circuit for supplying steady energy to relay ZWCTM and thus cause the equipment for section 2T to assume its normal inactive condition.

It will be seen, therefore, that when the switch 3W is reversed the relay SRWP establishes a cir cuit for supplying energy from the winding 4l of transformer WDT to relay ZECTM so that as soon as a westbound train vacates section 2T, the equipment for the section assumes its no-rmal inactive condition even though at the time the section is vacated the relay 4LI-ISR has been operated to clear signal 4LB and therefore interrupts the circuit which it controls for supplying energy from winding 4I to relay ZECTM.

It will be seen that the track circuit apparatus for section 2T is arranged to be controlled by a C. T. C. system, and that the section is prepared for eastbound traf-lic as a result of movement of the contacts of relay ZRHSR to clear the signal 2BA governing entrance of eastbound trains into the section so no control functions in addition to those normally employed are required of the C. T. C. system to prepare section 2T for eastbound trafc.

The equipment for section 2T is conditioned for westbound traffic as a result of movement of the contacts of relay aLl-ISR to clear the signal 4LA governing entrance of westbound trains into section 2T together with movement of the contact of relay WFSR. The control of relay WFSR requires a control step in the C. T. C. system field station unit at the left-hand end of section 2T. However, as usually constructed, the C. T. C. system station units have a control step not assigned to other functions so a control step is available for the control of relay WFSR and a standard C. T. C. system may be employed.

If desired, the passing siding may be provided with track circuit apparatus similar to that provided for section 2T to thereby provide means for controlling signals ZRB and 4LB in accordance with traffic conditions in the passing siding and to also cause the C. T. C. system to indicate whether or not the passing siding is occupied. In addition, the track circuit apparatus in the passing siding will operate as explained in connection with section 2T to cause equipment on motor cars in the passing sidingV to indicate whether or not trains are authorized to enter the passing siding.

The track circuit apparatus for the passingA siding is preferably arranged the reverse of that for section 2T, so that the equipment at the lefthand end section 2T is at the right-hand end of the passing siding and the equipment at the right-hand end of section 2T is at the left-hand end of the passing siding. This arrangement of the track circuit apparatus for the main track and for the passing siding makes it possible to employ the spare control step in the C.- T. C. system field station unit at one end of the passing siding to control the track circuit apparatus for the main track, and to employ the spare control step in the field station unit at the other end of the passing siding to control the track circuit apparatus for the passing siding.

Furthermore, this arrangement of the track circuit apparatus for the passing siding and for the main track causes the C. T. C. system field station unit at one end of the passing siding to transmit indications of occupancy of the main track while the C. T. C. system field station unit at the other end of the passing siding to transmit indications of occupancy of the passing siding.

Although we have herein illustrated and described one form of railway signaling apparatus embodying our invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of our invention.

Having thus described our invention, what We claim is:

l. In combination, a section of railway track, a first signal governing entrance of traffic into the section at the first end thereof, a, second signal governing entrance of traffic into the section at the second end thereof, a first code following relay at the first end of the section operated by energy supplied over the section rails, a second code following relay at the second end of the section operated by energy supplied over the section rails, a first and a second control relay at the first end of the section, a third control relay at the second end of the section, each of said control relays having contacts which normally occupy a first position and which may be caused to occupy a, second position, means at the first end of said section effective when the contacts of said first and second control relays are in their first position to supply steady energy to the rails of said section, means at the second end of said section effective on cutting off of the supply of steady energy over the section rails provided the contacts of said third control relay are in their first position to supply master code energy to the section rails, means responsive to code following operation of said first code following relay provided the contacts of said first control relay are in their second position to cause said first signal to provide a permissive indication and to cause impulses of feed-back energy to be supplied to the section rails in the intervals between impulses of master code, meansv at the first end of said section effective when the contacts of said second control relay are in their second position to supply master code energy to the section rails, means responsive to code following operation of said second code following relay provided the contacts of said third control relay are in their second position to cause said second signal to provide a permissive indication, and means responsive to energiza-tion of said second code following relay by steady energy, by master code energy, or by feed-back energy for indicating occupancy of said track section.

2. In combination, a, section of railway track, a first signal governing entrance of traffic into the section at the first end thereof, a second signal governing entrance of traffic into the section at the second end thereof, a first code following relay at the first end of the section operated by energy supplied over the section rails, a second code following relay at the second end of the section operated by energy supplied over the section rails, a, first and a second control relay at the first end of the section, a third control relay at the second end of the section, each of said control relays having contacts which normally occupy a first position and which may be caused to occupy a second position, means at the first end ing operation of said second track relay provided the contacts of said third control relay are in their second position to cause said second signal to provide a permissive indication, means responsive to energization of said second track relay by steady energy, by master code energy, or by feedback energy for indicating occupancy of said intermediate section, means operative on movement of a train through said first section to cause the contacts of said first control relay to occupy their first position, means operative on movement of a tra-in through said second section to cause the contacts of said third control relay to occupy their first position, and means responsive to code following operation of said second track relay provided the contacts of said third control relay are in their iirst position to cause tlfe contacts of said second control relay to occupy their first position.

6. In combination, a stretch of railway track divided into a plurality of track sections including an intermediate section having at the first end thereof a first section and having at the second end thereof a second section, a first track relay at the first end of the intermediate section operated by energy supplied over the section rails, a second track relay at the second end of the intermediate section operated by energy suppiied over the section rails, a first signal governing entrance of traffic into said intermediate section at the iirst end thereof, a second signal governing entrance of traic into said intermediate section at the second end thereof, a first and a second control relay at the first end of said intermediate section, a third control relay at the second end of said intermediate section,- each of said control relays having contacts which nornially occupy a firstJ position and which may be caused to occupy a second position, means at the first end of said intermediate section effective when the contacts of said first and second control relays are in their first position to supply steady energy to the rails of said intermediate section, means at the second end of said intermediate section effective on cutting off of the supply of steady energy over the section rails provided the contacts of said third control relay are in their first position to cause master code energy to be supplied to the rails of said intermediate section, means responsive to code following operation of said nrst track relay provided the contacts of said iirst control relay are in their second position to cause said first signal to provide a permissive indication and to cause impulses of feedback energy to be supplied t the intermediate section rails in the intervals between impulses of master code supplied to the section rails at the second end thereof, means responsive to energization of said first track relay for causing the contacts of said second control relay to occupy their first position, means at the first end of said intermediate section effective when the contacts of said second control relay are in their second position to supply master code energy to the section rails, means responsive to code following operation of said second track relay provided the contacts of said third control relay are in their second position to cause said second signal to provide a permissive indication, means responsive to energization of said second track relay by steady energy, by master code energy, or by feedback energy for indicating occupancy of said intermediate section, means operative on movenient of a train through said first section to cause the contacts of said iirst control relay to occupy their first position, means operative onv movement of a train through said second section to cause the contacts of said third control relay to occupy their iirst position, and means responsive to code following operation of said second track relay provided the contacts of said third control relay are in their rst position to cause impulses of feed-back energy to be supplied to the intermediate section rails in the intervals between the impulses of master code supplied to the section rails at the first end thereof.

7, In combination, a stretch of railway track divided into a plurality of track sections including an intermediate section having at the first end thereof a first section and having at the second end thereof a second section, a first track relay at the first end of the intermediate section operated by energy supplied over the section rails, a second track relay at the second end of the intermediate section operated by energy supplied over the section rails, a first signal governing entrance of traffic into said intermediate section at the first end thereof, a second signal governing entrance of traffic into said intermediate section at the second end thereof, a first and a second control relay at-the first end of said intermediate section, a third control relay at the second end of said intermediate section, each of said control relays having contacts which normally occupy a iirst position and which may be caused to occupy a second position, means at the first end of said intermediate section effective when the contacts of said first and second control relays are in their first position to supply steady energy to the rails of said intermediate section, means at the second end of said intermediate section effective on cutting off of the supply of steady energy over the section rails provided the contacts of said third control relay are in their first position to cause master code energy to be supplied to the rails of said intermediate section, means responsive to code following operation of said first track relay provided the contacts of said first control relay are in their second position to cause said first signal to yprovide a permissive indication and to cause impulses of feed-back energy to be supplied to the intermediate section rails in the intervals between impulses of master code supplied to the section rails at the second end thereof, means responsive to energization of said first track relay for causing the contacts of said second control relay to occupy their first position, means at the first end of said intermediate section eifective when the contacts of said second control relay are in their second position to supply master code energy to the section rails, means responsive to code following operation of said second track relay provided the contacts of said third control relay are in their second position to cause said second signal to provide a permissive indication, means responsive to energization of said second track relay by steady energy, by master code energy, or by feed-back energy for indicating occupancy of said intermediate section, means operative on movement of a train through said first section tc cause the contacts of said first control relay to occupy their rst position, means operative on movement of a train through said second section to cause the contacts of said third control relay to occupy their first position, and means responsive to code following operation of said second track relay provided the contacts of said third control relay are in their first position and said second section is not occupied to cause impulses of feed-back energy to be supplied toY the intermediate section rails in the intervals between the impulses of master code supplied to the section rails at the first end thereof.

8. In combination, a stretch of railway track divided into a plurality of track sections including an intermediate section having at the iirst end thereof a iirst section and having at the second end thereof a second section, a first track relay at the first end of the intermediate section operated by energy supplied over the section rails, a second track relay at the second end of the intermediate section operated by energy supplied over the section rails, a iirst signal governing entrance of trafc into said intermediate section at the iirst end thereof, a second signal governing entrance of traffic into said intermediate section at the second end thereof, a first and a second control relay at the first end of said intermediate section, a third control relay at the second end of said intermediate section, each of said control relays having contacts which normally occupy a first position and which may be caused to occupy a second position, means at the iirst end of said intermediate section effective when the contacts of said first and second control relays are in their iirst position to supply steady energy to the rails of said intermediate section, means at the second end of said intermediate section effective on cutting off of the supply of steady energy over the section rails provided the contacts of said third control relay are in their first position to cause master code energy to be supplied to the rails of said intermediate section, means responsive to code following operation of said first track relay provided the contacts of said first control relay are in their second position to cause Said first signal to provide a permissive indication, means responsive to code following operation of said first track relay for causing impulses of feed-back energy to be supplied to the rails of said intermediate section in the intervals between impulses of master code supplied to the section rails at the second end thereof provided the contacts of said first control relay are in their second position or are in their first position and said iirst section is occupied, means responsive to energization of said first track relay for causing the contacts of said Second control relay to occupy their first position, means at the first end of said intermediate section effective when the contacts of said second control relay are in their second position to supply rnaster code energy to the section rails, means responsive to code following operation of said second track relay provided the contacts of said third control relay are in their second position to cause said second signal to provide a permissive indication, means responsive to energization of said second track relay by steady energy, by master code energy, or by feed-back energy for indicating occupancy of said intermediate section, means operative on movement of a train through said first section to cause the contacts of said iirst control relay to occupy their lirst position, means operative on movement of a train through said second section to cause the contacts of said third control relay to occupy their first position, and means responsive to code following operation of said second track relay provided the contacts of said third control relay are in their first position to cause impulses of feed-back energy to be supplied to the intermediate section rails in the intervals between the impulses of master code supplied to the section rails at the iirst end thereof.

9. In combination, a section of railway track, a first track relay at the first end of said section operated by energy supplied over the section rails, a second track relay at the second end of said section operated by energy supplied over the section rails, a coding relay controlling the supply of energy to the section rails at the second end of the section, means for at times supplying energy to the section rails at the first end of the section, a circuit governed by a contact of said second track relay for supplying energy of a first code frequency to said coding relay, and a circuit independent of said second track relay contact for supplying energy of a second code frequency to said coding relay.

10. In combination, a section of railway track, a first track relay at the rst end of said section operated by energy supplied over the section rails, a second track relay at the second end of said section operated by energy supplied over the section rails, said second track relay having contacts biased to a rst position and movable therefrom to a second position when energy is supplied to the relay winding over the section rails from the first end of the section, a coding relay effective when operated by coded energy to cause coded energy to be supplied to the section rails at the second end thereof, a circuit for supplying coded energy of a iirst code frequency to said coding relay, said circuit being interrupted when the contacts of said second track relay are in their second position, a circuit independent of the contacts of said second track relay for supplying energy cf a second code frequency to said coding relay, and means for at times supplying energy to the section rails at the first end thereof.

l1. In combination, a section of railway track, aiirst track relay at the first end of said section operated by energy supplied over the section rails, a second track relay at the second end of said section operated by energy supplied over the section rails, said second track relay having contacts biased to a first position and movable therefrom to a second position when energy is supplied to the relay winding over the section rails from the first end of the section, a coding relay effective when operated by coded energy to cause to be supplied to the section rails at the second end thereof impulses of master code energy which are separated by intervals during which energy is not supplied to the section rails, a circuit for supplying coded energy of a first code frequency to said coding relay, said circuit being interrupted when the contacts of said second track relay are in their second position, a circuit independent of the contacts of said second track relay for supplying energy of a second code frequency to said coding relay, and means for at times supplying steady energy to the section rails at the first end thereof and for at other times supplying to the section rails at the iirst end thereof in the intervals between impulses of master code energy impulses of feed-back energy effective to maintain the contacts of said second track relay in their second position only for periods shorter than the intervals between impulses of master code energy of said first code frequency.

HENRY A. TALBERT. CRAWFORD E. STAPLES.

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