US2357234A - Coded railway signaling apparatus - Google Patents

Description

Filed Dec. s, (1943 QXL NMVIL L ||||||L R@ Y Nw QM NS uw. H, .f mw WM EN .m b NW d B il IL Uf Sw ww Vm Y n w v 5@ ww AIlv YN VM Patented Aug1 29, 1944 UNITED STATES V:PATENT oFF-ICE Crawford E. Staples, Pittsburgh, Pa., assigner to The Union Switch &`Signal Company, Swiss- `vale, Pa., a corporation oilllfsylvania Applicationpecember 3, 1943,.Sernin).` 512,723

s 'claims lol. 246-63) .My inventionrelatesto arailway signaling system vfor use in single track stretches through which are .operated locomotives equipped with cab signal apparatusresponsive to now-of coded alternating current inthe track rails.

In application forLetters Patent of thefUnited States :Serial No. 412,279, iiled September 25, 1941, byJames J. Van Horn, now Patent No. 2,344,333,.granted March 14, 1944, there is shown a signaling system for a single track railroad over which traicfmay move in either direction. In V.the system shown in that application each tracksection in the trackstretch, except for the portions of `the track stretch adjacent a highway intersection orother location where short detector track circuits are required, is equipped with two track circuits, one for each direction of traic. Means .are provided to attimes supply steady'energy to either end of the vtrack stretch, while the track circuits are arranged so that when the track stretch is vacant, this steady energy is cascaded Yfrom one section to another throughout thetrackstretch to energize traffic locking means at the other end of the track stretch and thus permit-the direction of traflic in the track stretchY to be reversed. In addition, there are means at each end of the track stretch effective after the stretch has been conditionedv for eithervdirection of traffic to supply coded energy to the section at the exitend of the track stretch, and the track circuit apparatus for each section is arranged so that this coded energy is cascadedfrom one section to another to the entrance end of the track stretch to control the signal at the entrance end of the stretch.

. Asshown in Fig. 4 of the application identified above, where a highway crossing is encountered, track sectionsemploying steady energy track circuitsare provided on either side of the intersection tor control the highway crossing signals; while a line circuit yis provided to carry around the approach sections Vat the highway crossing the steady and coded trafc governing. energy employed in the rest of the track stretch.k

In track stretches in which are operatedlocomotives equipped withqcab signal apparatusresponsive to ow -of coded alternating currentin the track Vrails it is necessary Vto arrangelthetrackway` apparatus so that coded alternating current is supplied to the rails of each track section at the exit end of the section. A v

It is an object of this invention to provide means for use in a system ofy the` type described for supplying'codedVV alternatingcurrent to the coding relays whichcontrol the supply of coded alternating. current to the detector track. sections are energized from the line circuit over which coded traffic governing energy is transmitted around the detector sections.

' #Another object ofthe rinvention isto provide a system of the type describedwhich is arranged soithat one coding -relayisconnected across Vthe line circuit `when the stretch is conditioned for one-directionoftratc and a second coding relay is connected across the line circuit `when the stretch is.conditioned. forthe other direction of traIic.

A further object of theinvention is to provide a system .of the type described which is arranged so .that .the coding relays associated Vwith the crossing arenormally disconnected from the line circuit and. become connected'thereto vonly after anapproachsectionis occupied. ...Another object .of the invention vis to provide a system of the type described which is arranged so that .only .one coding relay. is connected to the line circuit at .one time. l l

vOther objects. ofthe invention and features of noveltywill be apparent'from the following descriptiontakenrin connection with. the accom-- panying drawing, the single figure of vwhich is a diagramiHustrating a section of railway-track equipped with apparatus. embodying vmy invention.l

I shall describe one'form of coded railway signaling. apparatus (embodying my invention and shallthen point out .the novelteatures thereof in claims.

In practicing myinve'ntionI provide two cod--y ing relays at the highway intersection and -employ one ofv these to' supply coded alternatingcur' rentzto the ...track'transformers atthis locationon movement cfa train-through the track stretch in one direction, .andfemploy the other codifng relaylto supply .codedalternating current tothe track 'transformers' at this location Von n iove mentfof atrain through the track stretch in the other direction. rAs longV Vas-thel approach ls'ections. arevacant the circuit of the line wires/extending around theseV sections is complete-and coded or Ysteady .tra'ic .governing energy maybe transmitted .over these 'line Wires'.between` the sectionsA .at` either side of the. approach sections,- whilethe coding relays at the highway intersectionsare.;deenergized. When ya train enters-van short section which includes the highway intersection, the coding relay is maintained energized from the line wires by a circuit established by one i of the directional stickfrelays for the crossing signals, while the track relay for the intermediate section controls the supply of coded energy to the approach sections.

In the drawing there isrshown a stretch of single track railroad over which traffic may move in either direction. The track stretch includes an intersection with a highway vand this crossing is protected by suitable crossing signals XS, while the track stretch is divided into rsuitable track sections for controlling the crossing signals. This invention is directed to means for supplying coded alternating current cab signal control energyv to the. short track section which includes the highwayA crossing, and to the approach sections at either side of this section. This invention is not concerned with the apparatus at other points in the track stretch or at the ends of the single track stretch except insofar as the equipment of this inventionv is intended to operate/.in conjunction with that apparatus, and the equipment at those locations may be constructed as shown in application Serial No. 412,279 of James J. Van Horn.

* In order to simplify the disclosure and facilitate understanding ofmy invention, only the equipment for the approach sections, and for the adjacent ends of the adjoining sections has been shown in the drawing.

The rails l and 2.0i the track stretch are divided by means of the usualfinsulated rail joints 3 into a number of track sections. Each of these sections is identified by the reference character T with a distinguishing prex which also identifies Vthe apparatus associated with that section.

To facilitate description of the equipment it will be assumed that the right-hand end of the stretch is east and that the left-hand end of the stretch is west so that train movements from leftto right are eastbound and train movements from right to left are westbound.

The track section 'ICT' is a relatively short sec-y tion which includes the highwayV intersection. This section has at one side the eastbound approach section'Y'lBT, and at the other side the westbound approach section IDT, while means governed by tranic conditions in these sections are provided to control the relay XR which gov' erns the crossing signals XS.

, The short intermediate section 1CT is provided-for the purposeof insuring that on move-A ment of a train through the track stretch in either direction, operation of the crossing signals will be continued until the train clears the intersection. If this method of operation of the crossing signals is not required, the section TCT may be-omitted and the approach sections 'BT'and 1DT. mayr adjoin.

- In the system shown in the drawing the track relays 1BTR and TDTR cooperate with the track relay 'ICTR of theintermediate section 1CT to control directional stick relays WSR and ESR, andthe crossing signal control relay XR.. However, the invention is not limited to the usev of this form of ,crossing signal control apparatus section Vand a track relay, designated TR with an appropriate prefix, connected across the section rails at the other end of the section.

Each track section in the track stretch is provided with a track transformer at each end of the track section. These track transformers are designated TT with an appropriate prefix Vto indicate thev track section with which the transformer is associated, and also the end of the section at which it is located.

The track transformers located at the ends of sections 1BT, 'ICT and 'IDT at which the Vtrack batteries are located have their primary windings {connocted in series with the track battery, while these primary windings are of relatively low resistance so as not to unduly restrict the supply of energyfrom the track batteries to the section rails.

The track transformers located at the track relay ends of sections have their primary windings connected in multiple with track relays, while resistors are 'included in series with the track transformer windings to restrict flow of track circuit energy in these windings. The track relay windings have such high impedance to alternating current that little energy from the track transformers flows in the relay windings.

As explained in the above-identified application of James J. Van Horn, each of the track sections IAT and IET is provided with two track circuits, one eastbound and one westbound. Each track circuit for each of these track sections includes a code following track relay vat one end of the track section and a track battery at the other end of the section, and at each end of the section a coding relay CTM having contacts controlling connection of the associated track battery and track relay with the sec- Ation rails.

Each of the code following track relays has associated therewith a front contact repeater relay FSA and a back contact repeater relay BSA.` The relays FSA and BSA are of a type the contacts of which are slow to release, while each of these relays may have a snubbing resistor connected across the terminals of its winding to increase the release period of the relay. The relays FSA rand BSA are proportioned so that their contacts will remain picked up throughout 'the longest code interval during which the supply of energy to the relay is interrupted. i e

The equipment at the highway intersection includes coding relays'CTMW and-CTME which operate as hereinafterexplained to cause coded alternatingcurrent energy to loe-supplied to section 'ICT and to section BT or section DT.

.The relays and other equipment except the track relays are supplied from suitable sources of direct current, such as storage batteries, not shown, located at appropriate points inthe track stretch. The terminals of these sources are designated B and C in the drawing.

The alternatingv current supplied to the track transformers may be supplied from any suitable source, not shown, the terminals of which vare designated BX and CX in the drawing.

VThe construction and operation of the cab ksignal apparatus on the locomotives operated in the -track stretch are not a part of this invention, and

have not been shown in order to simplify-the disclosure. The cab signal apparatus may be constructed as shown in Letters Patent of the United States No. 1,986,679, issued January l, 1935, to L. V. Lewis.

The equipment is shown in the condition which it assumes when the track stretch is vacant and steady energy is supplied at the east end of the track stretch.v As explained in the Van Horn .application identified above, steady energy is sup,- plied at the east end of the track ,stretch and is cascaded from one track section to another Vto the West end of the stretech to energize traiiic locking means at that point. The apparatus provided by this invention for the approach sections is arranged so that on the supply of steady energy to either end of the track stretch it will be transmitted over a `line circuit around the approach sections to the portionof the track `stretch at the other side of these sections. As steady energy is supplied to the east end of section 'ET this energy feeds over back contacts of coding relay 'lWETCM and picks up track relay TEETR so that energy is supplied over front contacts 20 and .2i of track relay IEETR to line Wires 22 and 23, and over back contacts 25 and v28 of track relay 'IWATR to coding relay fmliC'IM.` The circuit of line wire 23 includes front contact 21 of relay l'DTR, front contacts 28 and 29 of track relay lCTR, and front'contact 30 of track relayglBTR. f Accordingly, when sections TET, lC'I and VDT, are vacant, the circuit of line wires 22 and 23 is complete and ,steady energysupplied to the line wires over front contacts of relay 'lEETRissupplied over the line wires to relay 'FEACTM and keeps its contacts 32 and 33 picked up so that steady energy is supplied from the track battery -IEATB and from the tracktransformer 'IEATB and from the track transformer EATZI I tofthe rails of section IAT. The steady energy supplied from track battery 'IEA'IBto the rails of section 'iATpicks up the track relay, not shown, at the West end of this section and .causes the supply of steady energy to be repeated throughout the ,other tra-ck sections to the west end of the single vtrack stretch. As the track .stretch is vacant, energy is supplied to relay XR over the circuit which includes front contact 35 of `relay 1CTR, frontcontact 36 of relay TDTR and front contact 3'! of Vrelay 'IBTR so contact 38 of relay XR is picked up and interrupts the circuit of crossing signals XS .to

prevent their operation at this time.

At this time Ithe directional stick relays WSR and ESR are released, while the circuits ofthe coding relays -CTMW and CTME are interrupted so ,that the contacts of these relays are released anddo not establish the vcircuits of the associated track transformers. v

kIf it is desired to condition the stretch to permit a westbound train to pass through the stretch, means -not shown, at the right-hand or east end of vthestretch are operated to permit clearing of the westbound signal at that point and to cut oiT the supply of steady energy tothe east end of the stretch. When the supply of steady energy to the stretch isinterrupted', the track .relay Vfor each section releasesand .cuts off the supply *of steadyenergy to the adjoining section so the supply of steady energy is cut off from the various sections in succession throughout the and cuts 01T the supply of steady energy to linev wires 22 and 23 so relay 'IEACTM releases and cuts oi the supply of energy from battery IEATB and transformer 'IEATT to the rails of section 'IAT and connects track-relay IWATR across the section rails.

When the supply of steady energy at the west end of the stretch is cut oif, apparatus, not shown, at that location causes coded energy of suitable code frequency, such as 75 or 180 code frequency, to be supplied to the west end of the track stretch. The means for causing coded energy to be supplied to the west end of the stretch are not a `part of ,this invention, and are shown and described in the application of J.J. Van Horn, identified above.

On the supply of coded energy to the west end of the track stretch, coded energy is cascaded through the successive track sections to section 'IAT and coded energyis supplied over back contacts 32 and 33 of relay 'lEACTM to relay IWATR.. Accordingly, relay 'IWATR follows code and energy is supplied over its front contacts 25 and 26 to line Wires 22 and 23, and is supplied over vthese line wires and over back contacts 20 and 2| of relay TEETR to relay IWECTM and Operates it to supply coded energy from the track battery 'IWETB andxfrom the track transformer 'IWETT to the rails of section TIET, while the track circuit apparatus, not shown, at the east end of section 'IET causes coded energy to be repeated into the adjacent section.

In addition, as a result of code following voperation or track relay 'EWATR relays 'iWAFSA and TWABSA are picked up, and contact 40 of relay 'IWABSA establishes thercircuit controlled by contact l of track relay IWATR for supplying energy to the primary winding of track transformer lWBTT. Accordingly, coded alter- -nating current .is supplied to 'the rails ofvsection 'iBT at the exit end of the section, while the code frequency of this energy is determined by the rate of operation of track relay lWATR.

When the westbound train enters section DT, track relay 'l-DTRreleases and its contact 2l` interrupts the supply of energy over the line wires 22 and 23 to coding vrelay 'EWECTM .and connects Wire 23 to one terminal of thewind'- ing g of coding relay CTMW, the other .terminal oivwhich is connectedto wire 22.k Accordingly, relay CTMW is connected across line wires 22 and 23 and is operated by coded energy supplied to these wires as a result of operation of relay IWATR; When coding relay CTMW is operated by energy from line wires 22 and 23, coded energy is suppliedover front contact i3 of relay 1CTR and contact B4 of relay CTMW to the primaryr winding of track transformer lWD'I'I so that coded cab signal control energy is supplied to the rails of section 'EDT at the exit end of the section, while the code frequency 'of this energy is governed by the rate of operation of relay CTMW which is determined by the rate of `,operation oi relay 7WATR. The vcoded alternating current supplied to the rails of section lDT operates the cab signal .apparatus on the locomotiven this section .to provide an appropriate signal indication.

lOn coding operation of relay CTMW, coded alternating current is supplied over its contact 48 to transformer TWCTT and thus to the rails of section 'ICT to operate the cab signal equipment when the locomotive advances into section `lCT.

In addition, on release of relay 1DTR, its contact 36 interrupts the circuit of relay XR so that contact 38 of relay XR releases and initiates operation of the crossing signals XS. O'n release of relay 1DTR, a pick-up circuit is established for relay WSR and includes front Contact 45 of relay 1BTR, back contact 46 of relay 1DTR, and back contact 41 of relay ESR. Accordingly, relay WSR picks up at this time.

When the train enters section 1CT, track re? lay 'ICTR releases and its contact 43 interrupts the circuit traced above for supplying coded alternating current to track transformer 'lWDTT, but does not affect the circuit including contact 48 of coding relay CTMW for supplying energy to the track transformer 'IWCTT so that cab signal control energy continues to be supplied to the rails of section ICT at the exit end of the section.

On release of relay 1CTR, its contact 35 establishes a stick circuit for relay WSR. This circuit includes back contact 35 of relay lCTR and front contact 50 of relay WSR and maintains relay WSR picked up when relays lDTR and IBTR are both released or are both picked up.

In addition, on release of relay 1CTR, its contacts 28 and 29 additionally interrupt the circuit of line Wire 23, while wire 23 is connected over back contact 29 of relay 'lCTR and front contact I of relay WSR to the right-hand terminal of the winding of relay CTMW so that relay CTMW continues to be operated by energy supplied over line wires 22 and 23 even though on release of track relay lCTR, the circuit controlled by, relay 'lDTR for connecting relay CTMW across the line Wires is interrupted.

When the train advances into. section 1BT, track relay IBTR releases and its contact 30 interrupts the circuit of line Wire 23 and cuts 'off the supply of energy to coding relay C'IMW and it ceases to operate so that energy is no longer supplied to the track transformers TWCTT or 1WDTT.

When the train enters section 1BT, the cab signal apparatus on the locomotive is operated by coded alternating current supplied to the section rails through transformer IWBTT at the west end of the section.

In addition, when relay 'IBTR releases, its back contact 45 closes so that when the train vacates section IDT, energy is supplied to relay WSR over the stick circuit which includes front contact 46 of relay 1DTR, back contact 45 of relay 'IBTR and front contact 52 of relay WSR so relay WSR remains picked up after the train vacates section 'ICT and track relay TCTR picks up and its contact A35 interrupts the stick circuit which it controls for supplying energy to relay WSR. l v

When the train advances into section TAT, track relay IWATR remains released so coded energy is no longer supplied to the West end of line wires 22 and 23 and these wires are connected to coding relay 'IEACTM.

In addition, when relay 'IWATR ceases to follow code, relays TWAFSA and 'IWABSA release so that contact 40 of relay 'IWABSA interrupts the circuit of transformer TWBTT.

' When the train vacates section lCT, the track relay 'lCTR picks up and energy is supplied over front contact 35 of relay 1CTR, front contact 36 of relay 1DTR, and front contact 54 of relay WSR to relay XR so that its contact 38 picks up to discontinue operation of the crossing signals XS.

When the train vacates section 1BT, track rellay 'IBTR picks up and its contact, 31 completes the circuit including front contact 35 of relay lCTR and front contact 36 of relay 'IDTR for supplying energy to relay XR so that relay XR remains picked up to prevent operation of the crossing signals. In addition, on picking up of .relay lB'I'R, its contact 45 interrupts the stick circuit which it controls for relay WSR and relay WSR releases.

When sections IDT, 'ICT and 'IBT are vacated .and the track relays for these sections are picked up, the circuit of the line Wires 22 and 23 is complete, while coding relays CTME and CTMW are both disconnected from the line Wires.

As explained in the above-identied application of J. J. Van Horn, steady energy may be supplied to the track stretch behind the train, and this steady energy Will be cascaded throughout the track'stretch as each track section is vacated. Accordingly, after the train vacates section lET, steady energy supplied at the east end of the section feeds over the back contacts of coding relay 'IWECTM and picks up the contacts 20 and 2l of relay 'IEETR so that the circuit of relay 'IWECTM is interrupted and it is certain to remain released and maintain the circuit of track relay 1EETR. In addition, When relay 'IEETR picks up, it contacts 2l and 20 connect line wires 23 and 22 to the terminals B and C of a source of current, and when relays lBTR, 'lCTRfand 'IDTR are picked upto complete the circuit of line wires 22 and 23, energy is supplied over these line Wires and over back contacts 25 and 26 of track relay 'IWATR to coding relay 'IEACTM so that its contacts pick up to cause steady energy to be supplied to the rails of section 'IAT and to interrupt the circuit of relay 'IWATR so that itlremains released and maintains the circuit of relay 'lEACTlVL As track relay IEETR is steadily picked up, relay 'IEEBSA remains released and prevents supply of energy to track transformer 1EDTT.

If the steady energy supplied at the east end of the track stretch is now out off, and coded energy substituted therefor, this coded energy will be cascaded throughout the track stretch to condition the signal at the West end of the stretch to permit an eastbound train to enter the stretch.

On movement of an eastbound train through the track stretch, the equipment at the highway crossing operates in a similar manner to that described in detail above on movement of a Westbound train through the track stretch.

When the stretch is conditioned for eastbound trahie, track relay lEETR follows code and causes coded energy to be supplied to the line Wires 22 and 23 at the right-hand or east end thereof, while this energy is supplied over the line Wires to relay lEACTM and operates it to cause coded energy to be supplied to the rails of section 1AT. As a result of codingV operation of relay 1EETR, the relays 'IEEFSA and 'IEEBSA are both picked up and contact 5B of relay lEEBSA establishes the circuit including contact 51 of track relay 'IEETR for supplying coded energy to track transformer TEDTT.

When an eastbound train enters section 1BT, track relay 'IBTR releases and its contact 30 inrelay 1BTR to relay XR so that contact 36 of relay terrupts the circuit of line wire 23 and connects 'this line'Wire to the left-hand terminal of. the

winding of coding relay C'IME, the other terminal of Which is connected to Wire 22. Accordingly, re-

supplied over front contact 43 of track relay 1CTR Y and contact 58v 'of relay CTME to the primary winding of track transformer 1EBTT so that coded alternating current energy is supplied to the rails of section 1BT to operate the cab signal apparatus on the Vlocomotive present in section 1BT. In addition, on coding operation of rela;r CTME, coded alternating current is supplied over its contact 60 to transformer 1ECTT and thus to the rails of section 1CT to operate the cab signal equipment when the locomotive advances. into section 1CT.v

On release of relay 1BTR, its contact 31 interrupts the circuit of relay XR and its contact 38 Vreleases and initiates operation of the crossing signals XS. Also on release of relay 1BTR,a pick-up circuitY is established forl relay ESR and is traced over vfront contact 46 of relay 1DTR, back contact 45 of relay 1BTR and back contact 52 of relay WSR, and relay ESR picks up at this time.

When the train advances into section 10T, track relay 1CTR releases and its contact 43 cuts off supply of energy to transformer 1EBTTbut does not affect the circuit controlled by contact 60 of relay C'IME for supplying energy to transformer 1ECTT so that coded energy continues to be supplied to the rails of section ICT to operate the cab signal apparatus While theY locomotive is in this section. i

In addition, on release of relay 1CTR, its back contact 25 establishes a stick circuit for relay ESR, this circuit including front contact 6l of relay ESR. Also on release of relay 1CTR, its

`contacts 28 and 29 additionally interrupt the circuit of line wires 22 and 23, while contact 28 connects Wire 23 over front contact63 of relayESR to the left-hand terminal of the Winding `of relay CTME so that coding relay CTME continuesl to be operated by coded energy supplied to the line Wires 22 and 23 by track relay 1EETR.

When the train advances into section 1DT, track relay 1DTR releases and its contact 21 cuts off supply of energy over line Wires 22 and 23 to coding relay CTME and it ceases to operate. When the train is in section 1DT, the cab signal apparatus on the locomotive is operated by energy supplied from transformer 1EDTT.

When the. train advances into section 1ET, track relay 1EETR remains released and connects line Wires 22 and 23 to coding relay 1WECTM, While relays 1EEFSA and TEEBSA release so that energy is no longer supplied to trans.- former 1EDTT.

On release of relay 1DTR,rits back contact 46 is closed so that when the train vacates section 1BT and track relay 1BTR picks up, energy is supplied to relay ESR over the stick circuit which includes front contact 45 of relay 1BTR, back contact 46 of relay 1DTR, and front contact 41 of relay ESR. The energy supplied over this circuit keeps relay ESR picked up after the train vacates section 1CT and track relay 1CTR picks up.

When track relay 1CTR picks up, energy is supplied over front contact of relay 1CTR, front contact 65 of relay ESR, and front contact 31 of XR picks up to discontinue operation of the crossing signals XS.

When the train vacates section 1DT, track relay 1DTR picks up and its contact46 interrupts the stick circuit for relay ESR so that it releases, but at this time relay XR is maintained energized by current supplied over front contact 36 of relay 1DTR.

When track relays 1BTR, 1CTR and 1DTR are picked up, the circuit of ther linevvires 22 and 3 is complete, and if steady energy is supplied to the West end of the track stretch so that track relay 1WATR is picked up to cause steady energy to be supplied to the line Wires 22 and 23, this energy Will be supplied over the line Wires and over back contacts 20 and 2l of relay 1EETR to coding relay 1WECTM so that its contacts are picked up to cause steady energy to be supplied to the rails of section 1ET and to interrupt the circuit of track relay 1EETR so it vremains released and maintains the circuit of relay 1WECTM.

It Will be seen that the equipment is arranged so that, when the track stretch isvacant, the circuit of the line wires extending around the approach sections for the highwayA crossing is complete and coded or steadyA energy may be transmitted over these lin'e Wires to control traflic in the track stretch. When the stretch is vacant, the coding relays at Ythe crossing are oleenergized and cab signal control energyisnot supplied to the approach sections. AAs long as one of the* approach sections is occupied, the supply of energy over the line wires to the coding relays at the ends of the line circuit is prevented, While as soon as a train enters one of the approach sections, one or the other of the coding relays at the crossing Yis connected across the line Wires so as to be operated to supply to the track sections at the exit ends thereof coded cab signal control energy of appropriate code frequency. As the system is arranged so that only one coding relayV is connected across the line Wires at one time, the coding relays will not interfere With each other, and will operate to supply to the track rails coded energy of accu-r rate code pattern. A

While the invention has been lillustrated andr described in connection `With a' tra ck stretch equipped With signaling apparatus of thev type shown in applicationSerial No. 412,279 ofA James J. Van Horn, in which both steady and coded trac governing energy is employed, the invention is not limited to use in such situations, but is equally applicable to track stretches equipped with signaling systems of other' types in which coded energy is supplied atY one end ofthe stretch at times and is supplied at the other end of the stretch at other times.

Although I have herein shown and described only one form of coded railway signaling apparatus embodying my invention, it is understood that various changes and modications may be made therein within the scope of the appended claims Without 'departing from the spirit and scope of my invention. Having thus described my invention, What I claim is: 1. In cab signal energy supply means for use in a stretch of railroad track over which may move in either direction locomotives equipped with cab signal` apparatus responsive to the presence ofcoded alternating current in the track rails, the rails of the track stretch being divided into a plurality of successive track sections 4including a rst, second, a third and afourth section, said track stretch being providedA with traflic governing apparatus of atype in which coded energy is supplied to one end'of the track stretchv at given times and is supplied to the otherend of the stretch at other times, said second Vand third track sections each being provided With a track circuit including a track relay, a pair of line Wires substantially coexten'sive with said second and third track sections and governed by the track relays of said track sections, the first and fourth track sections each being provided with track circuits employing coded energy and each having at the end of the section adjacent the end of the line Wires coding means responsive to the supply of coded energy over the section rails from the opposite end. of the section for supplying coded energy to the line wires and for also supplying coded alternating current to the rails of the adjoining track section, said first and fourth track sections each being provided with coding means operated by coded energy supplied over the line wires and controlling the supply 'of coded energy to the section rails at the end of the section adjacent the line wires, in combination, a iirst coding device controlling the supply of coded alternating current to the rails of the third track section at the end of said section adjacent the second track section, a second coding device controlling the supply of coded alternating current to the rails of said second track section at the end of said section adjacent the third track section,

means effective on release of the track relay for the second section to prevent the supply of energy over the line Wires to the coding means for the rst section and to connect the second coding device across the line wires so that said second coding device is operated by coded energy supplied to said line wires at the end thereof adjacent the fourth track section, and means effective on release of the track relay for the third section to prevent the supply of energy over the line Wires to the coding means for the fourth section and to connect the first coding device across the line Wires so that said rst coding device is operated by coded energy supplied to said line Wires at the end thereof adjacent the rst track section.

2. In cab signal energy supply means for use in a stretch of railroad track over which may move in either direction locomotives equipped with cab signal apparatus responsive to the presence of coded alternating current in the track rails,-the rails of the track stretch being divided into the plurality of successive track sections including a nrst, a second, a third and a fourth section, said track stretch being provided with traic governing apparatus of a type in which coded energy is supplied to one end of the track stretch at given times and is supplied to the other end of the stretch at other times, said second and third track sections each being provided With a track circuit including a track relay, a pair of line wires substantially coextensive with said second and third track sections and governed by the track relays of said track sections, the rst and fourth track sections each being provided with track circuits employing coded energy and each having at the end of the section adjacent the end of the line wires coding means responsive to the supply of coded energy over the section rails from the opposite end of the section for supplying coded energy to the line Wires and for also supplying coded alternating current to the rails of the .adjoining track section, said rst and fourth track sections each being pro- Wvidedf with coding means operated by coded energy supplied over the line Wires and controlling the supply of coded energy to the section rails at the end of the section adjacent the line Wires,

.When the track relay for, the second section is released and the track relay for the third section is picked up to permit energy supplied to the line wires at the end thereof adjacent thevfourth track section to be supplied to said second coding device, and means effective when the track relay lfor the third section-is released and the track relay for the second section is picked up to permit -energy supplied to the line Wires at the end thereof adjacent` the iirstV track section to be supplied to said first coding device.

3. In cab signal energy supply means for use inl a stretch of railway track over Whichmay move in either direction locomotives equipped with cab signal apparatus responsive to the presence of coded alternating current in the track rails, the rails of said track stretch being divided by insulated joints into an intermediate section having an approach section at each side thereof, said approach sections and said intermediate section each being provided with a track circuit including a trackrelay, said track stretch being equipped With traflic governing apparatus for conditioningthe track stretch for one direction of traflic or the other and including a pair of line Wires substantially coextensive' with saidl approach sections and over which coded energy may be transmitted between the track sections at the sides of said approach sections remote from said intermediate section, said traiiic governing apparatus being-elfective When-.the stretch is conditioned `for either direction of traflic to cause coded alternating current to bezsupplied to the rails of the approach section in advance of said intermediate section at the exit end of said approach section and to also cause coded energy to be supplied to the line wires at the end thereof in advance of said inter-mediate section, in combination, a coding device controlling the supply of coded alternating current to the rails of one approach section and to the rails of the intermediate section at the'exit ends of said sections for one direction of traflic, another coding device controlling the supply of coded alternating current-toV the rails of the other approach section and to the rails of the intermediate section at the exit ends of said sections for the other direction of traic, means controlled by the track relaysiof one of said approach sections and oi said intermediate'section for connecting one oi said coding` relays across said line Wires, and means controlled by the track relays of the other of said approach sections and of said intermediate section. for connecting the other of said coding relays across said line Wires.

4. In cab signal energy supply means for use inV a stretch of railway track over which may move in either direction locomotives equipped with cab signal apparatusresponsive to the presence of. coded alternating current in the track rails, the rails of said track stretch beingfdivided by insulated joints into an intermediate section having an approach sectionV at each side thereof, said approach sections and said intermediate section each being provided with a track circuit including a track relay, said track stretchv being equipped with traiiic governing' apparatus for conditioning the track stretch forone direction of traffic or the other and including a pair of line wires substantially coextensive with said approach sections andlover which coded energy may be transmitted between the track section'sfat the sides of said approach sections remote from said intermediate section, said traflic governing apparatus being effective when the stretch is' conditioned for either direction of traihcto cause coded alternating current to be supplied t'o the rails ofthe approach section in advance of' said intermediate section at 'the exit end of" said approa-ch section and to also cause coded energy to be supplied to the line wires at the end thereof in advance of said intermediate section, in combination, a coding device controlling thesupply of coded alternating current to circuits over which energy is supplied to the railsy of one approach section provided the track relay off' the intermediate section is picked up and to the rails of the intermediate sectionfat the eXit ends of said sections for one direction of trac,

another coding device controlling the supply of' coded alternating current to circuits over which energy is supplied to the rails'of the other approach section provided the track relay of the intermediate sectionV is picked up and to the railsy ofv the intermediate sectionat the eXit ends of said; sections for the other direcion of traflic. means controlled by the track relays of one of saidvapproach sections and of said intermediate section for connecting one of said coding relays across said line wires, and means controlled by the trackv relays of the other of said approach sections and of said intermediate section for connecting the other of said coding relays across saidline wires.

5. In a cab signal energy supply means for use in a stretch of railway track over which. may move in either direction locomotives equipped' with cab signal apparatus responsive to thepresence of coded` alternating current in the track rails, the rails of said track stretch being divided by insulated joints into an intermediate section having a rst approach section at one side and a second approach section at the other side, said approach sections and said intermediate section each being provided with a track circuit including a track relay, equipped with traffic governing apparatus for conditioning the track stretch` for one direction of traic or the other and including a pair of` line wires substantially coextensive with said approach sections and over which coded energy may be transmitted between the track sections at the ends of said approach sections remote from said intermediate section, said traic governing apparatus being eiiective when the stretch is conditioned to permit traiiic to move from the first to the second approach section to cause coded alternating current to be supplied to the` rails of the second approach section at the exit end thereof and to cause coded energy to be supplied to said line wires at the end thereof remote from said iirst section, said traiiic governing apparatus being effective when the stretch is conditioned to permit traffic to move from the second to the iirst approach section to cause coded alternating current to be supplied to the rails of the first aptothe railsv ofthe second approach section at the end thereof' adjacent the intermediate section and' to the rails ofthe intermediate section at the end thereof adjacent the first approach section,

means controlled' by the track relays of the first approach and intermediate sections for connecting' the first coding device across'said line Wires, and' means controlled by the track relays of the second approach and intermediate sections for connecting'thesecond coding device across said line Wires.

6. In a cab signal energy supply means for use in a stretch of railway track over which may move in either direction locomotives equipped with cab signalapparatus responsive to the presence of' coded alternating current in the track rails, the

rails of'said track stretch being divided by insulatedfjoints into an intermediate section having a first approach section at one side and a secondV approach section at the other side, said approach sections andv saidA intermediate section each beingprovid'edwith a track circuit including a trackl relay, said' track stretch being equipped with traflic governing apparatus for conditioning thev track stretch for one direction of traic or the other and including a pair of line Wires substantially coextensive with said approach sections and over which coded energy may be transmitted between the track sections at the ends of said appro-ach sections remote from said intermediate said track stretch 'being' section, said trafc governing apparatus being effctive when the stretch is conditioned to permit trailic to move from the rst to the secondapproach section to cause coded alternating ,current enlergyv to be supplied to said line wires-,at the end thereof remote from said first section, said traffic governing apparatus being effective when the stretch isv conditioned to permit traffic to move from' the second to the rst approach section to cause coded alternating current to be supplied to the rails of the rst approach section at the exit end thereof' and to cause coded energy to be supplied to said line Wires at the'end thereof remoteV from said second approach section, in combination', a rst coding device controlling the supply of coded alternating current/to circuits over which alternating current is supplied to the rails of said first approach section at the end thereof adjacent the intermediate section provided the track relay for the intermediate Section is picked up and over which alternating current is supplied to the rails of the intermediate section at the end thereof adjacent the second section, a second coding device controlling the supply of coded alternating current to circuits over which alternating current is supplied to the rails of said second approach section at the end thereof adjacent the intermediate section provided' the` track relay for the intermediate section is picked up and over which alternating current is supplied to the rails of the intermediate section at the end thereof adjacent the first section, means controlled by the track relays for thecflrst approach and Aintermediate track sections for connecting the first coded device across saidv linew ires, and means controlled by the track relays of the second approach and intermediate sections for connesting the Second coding device across said line wires. v v

7. In cab signal energy supply'means` for use in a stretch of railway track over which may move in either 'direction locomotives equipped with-cab signal apparatus responsive to the presence of coded alternating current in the Ytrackrails, the rails of said track stretch being divided by insulated joints into an intermediate section having a first approach lsection at one side and a second approach section at the other side, said approach sections andv said intermediate section each being provided with a track circuit including a track relay, said track stretch being equipped with traflic Y governing apparatus for conditioning the track stretch for one direction of traflic or the other and including a pair of line Awires substantially coextensive with said approach sections and over which coded energy may be transmitted between the track sections at the ends of said approach sections remote from said intermediate section, said traffic governing apparatus being effective when the stretch is conditioned to permit traino to move from the first to the second approach section to cause coded alternating current to be supplied to the rails of the second approach section at the exit end thereof and to cause coded energy to be supplied to said line wires at the end thereof remote from said first section, said traffic governing apparatus being effective when the stretch is conditioned to permit traffic to move from the second to the iirst approach section to cause coded alternating current to be supplied to the rails of the iirst approach section at the exit end thereof and to cause coded energy to be supplied to said line Wires at the end thereof remote from said second approach section, in combination, a

first coding device controlling the supply of cod-` ed alternating current to the rails of said first approach section at the end thereof adjacent the intermediate section and to the rails of the intermediate section at the end thereof adjacent the second approach section, a second coding device controlling the supply of coded alternating current to the rails of the second approach section at the end thereof adjacent the intermediate section and to the rails of the intermediate section at the end thereof adjacent the first approach section, means controlled by the track relays of the first approach section and of the intermediate section for supplying from said line wires to the rst coding device coded energy supplied to the line wires at the end thereof remote from the first approach section,.and means confor supplying from said line wires to the second coding device coded energy supplied to the line4 Wires at the end thereof remote from said second approach section.

8. In cab signal energy supply means'for use ina' stretch of railway track over which may move in either direction'locomotives equipped with cab signal apparatus responsive to the presence of coded alternating current in the track rails', the rails of said track stretch being divided by vinsulated joints into an intermediate section having a first approach section at one side and asecond approach section at the other side, said approach sections and said intermediate section each being provided with a track circuit including a track relay, said track stretch being equipped with traffic governing apparatus for conditioning the track stretch for one direction of traflic or the other and including a pair of line Wires substantially coeXtensive with said approach sections arid over which coded energy may be transmitted between the track sections at the ends of said approach sections remote from said intermediate section, said traflic governing apparatus being eective when the stretch is conditioned to permit traiiic to move from the first to the second approach section to cause coded alternating current to be supplied to the rails of the second approach section at the exit end thereof and to cause coded energy to be supplied to said line wires at the end thereof remote from said first section, said traffic governing apparatus being effective when the stretch is conditioned to permit traffic to move from the second to the iirst approach section to cause coded alternating current to be supplied to the rails of the rst approach section at the eXit end thereof and to cause coded energy to be supplied to said line wires at the end thereof remote from said second approach section, in combination, a first coding device controlling the supply of coded alternating current to circuits over which alternating current is supplied to the rails of said first approach section at the end thereof adjacent the intermediate section provided the track relay for the intermediate section is picked up and over which alternating current is supplied to the rails of the intermediate section at the end thereof adjacent the second section, av second coding device controlling the supply of coded alternating current to circuits over which alternating current is supplied to the rails of said second approach section at the end thereof adjacent the intermediate section provided the track relay for the intermediate section is picked up and over which alternating current is supplied to the rails of the intermediate section at the end thereof adjacent the first section, means controlled by the track relays of the rst approach section and of the intermediate section for supplying from said line wires to the first coding device coded energy supplied to the line wires at the end thereof remote from the first approach section, and `means controlled by the track relays of the second approach section and of the intermediate section for supplying from said line wires to the second coding device coded energy supplied to the line wires at the end thereof remote from said second approach section.

CRAWFORD E. STAPLES.

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