US2352743A

US2352743A - Coded signaling system

Info

Publication number: US2352743A
Application number: US494618A
Authority: US
Inventors: Crawford E Staples; Herman G Blosser
Original assignee: Union Switch and Signal Inc
Current assignee: Hitachi Rail STS USA Inc
Priority date: 1943-07-14
Filing date: 1943-07-14
Publication date: 1944-07-04
Anticipated expiration: 1961-07-04

Description

July 4, 1944. c. E. STAPLES ETAL 2,352,743

i I CODED SIGNALING SYSTEM Filed July 14:,A 1945 '6 'C Fly.;

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INVENTORS CI'awFdE. Szaplef and E EYHePma/zloffen H- 'h/pp k- WHP v THEIR ATTORNEY Patented July 4, 1944 -CDED SIGNALING SYSTEM Crawford E. Staples and 'Herman G. Blos'ser,v Pittsburgh, Pa., assignors to The Union Switch itv Signal Company, Swissvale, Pa., a tion of Pennsylvania Corpora,-

`Application July 14, 1941i, SerialNo. 494,618

10 Claims.

, Our invention relates to signaling apparatus employing coded energy.` 1 In Letters Patent of the United States No. 2,021,944 to Frank I-I. Nicholson there is. shown a signaling system in which master code is transmitted in one direction over a pair of conductors to operate a code following relay and thereby perform selected functions at one end ofthe conductors, while during the off periods in the master code feed-back energy is transmitted in the other direction over these conductors tooperate a feedback relay and thereby perform selected functions at the other .end of theconductors.

It has heretofore been proposed to control the polarity of the feed-back energy so that this energy is f normal polarity at times and is of reverse polarity at other times, and to provide one feed-back relay responsive toenergy of one polarity and another feed-back relay responsive to energy of the other polarityso that the feedback energy .may be employed to perform two different functions.v The systems of this type heretofore suggested have employed feed-back detector relays ofthe polar biased neutral type, the contacts of which release when the relaywinding is deenergized, and which when released become picked up when and only when energy of a particular polarity is supplied to the relay.

vIt is preferred toemploy feedback detector relays of the polar stick type for this purpose, and it is an object of this invention to provide an improved system employing feed-back energy of both polarties and having feed-back detector relays of the polar stick type.

Another objectief thisk invention is to provide an improved system of the type described which is arranged so that the contacts ofboth of the feed-back detector relays are moved to a selected one of.theirvpositionsiwhen mastercode energy is supplied to the conductors, and so that the contacts of one-of the feed-back detector relays are moved to their other position. by feed-back energy of one polarity, and so that the contacts of the other .one of thefeed-.back detector relays are moved to their other position by feed-back energy of the other polarity," t A further object ofthe invention'is to provide Another object of the invention is to provide a system incorporating coding means for revers-T ibly connectingv one of the feed-back ldetector relays'across the section rails and for supplying master code energy to' thesection rails in series with the rwindingsfof thefeed-back detector relays so that the master code energy moves the contacts of bothof the .feed-back detector relays to a selected position andso that the feed-back detector relays respond to different polarities of feed-back energy. i

A further object of the invention is to provide an improved system of the type described and incorporating meansy to ,delay reversal of the connection of one of the feed-backrelays with the track rails for a short period subsequent to interruption of the supply of master code to the track circuit and thus enable energy stored in the track circuit as :a resultof the supply of master code energy to thetrack railsto be dis` sipated before connectiony of the feed-back relay with the track rails isreversed to thereby prevent operation of the feed-back relay by energy stored in the track circuit. y

Other objects' of the invention and features of` novelty will be apparent from the following description taken in connection with the accom-A panying description. y

We shall describe two forms of coded signaling apparatus embodying our invention, and shall then point out the novel features thereof in claims. u

`In practicing o ur invention we provide two feed-back detector relays of the stick polar type, while we employ two coding relays which are arranged so that when the contacts of both re' lays are picked up, master code energy is supplied to the rails of a section of railway track, orother pair of conductors, over a circuit including in series therewith the windings of the feed-,- back'detector relays so vthat the contacts of both feedback relays areI moved to a selected position by master code energysupplied through their windings. The coding relays are also arranged so that one of these relays releases before the other and lso that the first one of the coding rean improved systemof. the type described which isadapted to be applied to' the track circuit of a section of railway track andwhich is arranged so that energy stored in the track circuit ,as a result of the supply o f master code energy tothe section rails cannot falsely operate either feed-v backdetector relay.

lays to :release 4interrupts the supply of master code to the' section rails, while the other coding relay reversibly connects one of the feed-back detector relays across "the section: rails so that both feed-back detector relays will respond in the same manner to master code but will respond only to ldifferent polarities offeed-back energy. The interval between' release of the first vcoding relay to interrupt the supply of master code energy to rails. In the system shown in Fig. 1 when the coding relays are picked up, the detector relays are connected in series across the section rails,

while in the system shown in Fig. 2 when thev coding relays are picked up, the feed-back detector relays are connected in multiple across the section rails.

In the drawing Fig. 1 is a diagram of a section of railway track equipped with track circuit apparatus embodying our invention, and

Y Fig. 2 is a diagram showing a different arrangement of apparatus which we mayemploy.

Similar reference characters refer to similar parts in each of the two views.

Referring to Fig. 1 of the drawing, there is shown therein a stretch of railroad track having track rails I and 2 divided by insulated joints 3 into track sections for signaling purposes. One

complete track section, designated 6T, together with portions of the adjoining sections 5T and 1T, is shown in the drawing.

The track circuit apparatus for section 6T is arranged so that master code of one frequency or another determined by occupancy of section 1T is supplied to the section rails at the righthand end of the section, while feed-back energy of one polarity or the other determined by occupancy of section 5T is supplied to the section rails atA the left-hand end of the section.

The equipment at each end of the track section includes a source of direct current, such as a storage battery, notshown, the terminals of which are designated B and C. v

The equipment is shown in the condition which it assumes when the track stretch is vacant. At this time relay 'II-I, which is controlled by traic in section 1T, is picked up, and relay EPC, which is governed by traffic in-section 5T, is also picked up. The relays 'IHfand SPC may be controlled in any appropriate manner. and in order to simplify this disclosure, the means for controlling these relays have not been shown.

As relay 'IH is picked up, its contact I0 estab lishes the circuit controlled by the contact of code transmitter IBGCT for supplying energy to coding relays SCTM and BCTMM and these relays. operate at the 180 code frequency. On closing of the contact of code transmitter IBIiCT energyv is supplied tothe winding of coding relay SCTM, and prior to picking up of the contacts of relay GCTM, is supplied over back contact I2 of relay ECTM to the winding of relay SCTMM, while on picking up of relay ECTM energy is supplied directly from the source to relay GCTMM BCTM and release of the contacts of relay ECTMM.

As explained below, the supply of energy from the track battery STB to the rails of section 6T is cut off when relay GCTM releases, and as explained in Letters Patent of the United States No. 2,285,891, issued June v9, 1942 to Herman G. Blosser, the interval between release of relay GCTM and release of relay SCTMM provides a period during which energy stored in the track circuit may be dissipated so that the relays 6WD and GWH will not be operated by this energy.

When relays BCTM and SCTMM are both picked up, master code energy is supplied from track battery GTB to the track relay GTR over the circuit which is traced from the positive terminal of the battery over track rail I, through the winding of track relay GTR, back contact I4 of relay GIR, track rail 2, winding of relay 6WD from left to right, front contact AI5 of relay ECTMM, winding of relay `IiWH from left to right, front contact I6 of relay'EC'I'MM, and front contact II of relay GCTM to the negative terminal of the battery.

The energy supplied over this circuit picks up the contacts of the track relay GTR, while it causes the contacts o'f relays 6WD and GWH to move to their normal position if they are'not already in that position.

On release `of the contacts of the code transmitter controlling the supply of energy to the coding relays GCTM and GCTMM, the relay BCTM releases and its contact I2 interrupts the circuit of relay GCTMM but the operating` characteristics of the relay SCTMM are such that its contacts remain picked up for a short period subsequent to release of the relay GCTM. I n addition, on release of relay BCTM its contact I1 interrupts the circuit of the track battery GTB and establishes a'circuit to connect relays 6WD and BWH across the section rails as .long as relay GCTMM remains picked up. rWhen front point of contact I'I of relay GCTM opens, the supply of energy from the battery GTB to the sectionrails is cut off, but because of the inductance ofthe track circuit, or of other conditions, energywlll continue to ow therein in the same direction in which it had been owing, and energy may still be flowing in the track circuit when theA back point of contact I'I closes. If energy is owing in the track circuit when back point of contact II closes, this energy will flow from rail 2 through the winding of relay 6WD from left to right, over front contact I5 of relay SCTMM, through the winding of relay GWH from left to right, and over front contact I6 of relay GCTMM and back contact II of relayCTM to track rail L. The direction of flow of this energy through the windingsfof relays 6WD and BWH is such as to hold the contacts of these relays in theirAleft-handV or normal position, that is, in the position to which they .were moved by the supply of master code energy through the relay windings.

On release of the contacts of relay BCI'MM the connection of the relay I iWH across the section rails is reversed so the left-hand terminal of the winding of this relay is connected to track rail I and theV right-hand terminal of the winding of l this relay is connected through the winding of BC'I'M release, while there will be a short time relay 6WD to track rail 2. If energy, resulting from inductance of the track circuit ory other condition should now ow from rail 2 to rail I through the windings of relays 6WD and EWH it would cause the contacts of relay GWH to move from their left-hand to their right-hand position.

time intervalbetween the instantat whi'chwsol'r-fv tact, H of relay BCTM releases and." interrupts the circuit of the battery STB', and the instant at which relay SCTMM releases to reverse con nection of` relay GWH .with the track rails, and this time interval is long enough to permit en'-Y .ergy' present in the track circuit as a result of. supply of energy to -thei track circuit from the track battery to be dissipated. Accordingly, there isno possibility that'the relays 6WD and SWH will be operated yby energy stored in the track'circuit Y vOn interruption of the supply of energy'frorn .the track battery r STB tol the1 sectiorr` rails the track relay SI'R releases, While onjrelease of the vvtrack vrelay contacts an impulse'of energy is supplied through the decoding transformer GDTV to the relay STR, and yis of' the polarity eflective to pickJ up theV contacts of relayv SIR to thereby cause an impulse' of energytdbe supplied from battery SFB to the sectionfrails while disconnecting Vthe track relay from the'sectlon rails.v

vAn impulse of Yenergy was also supplied from the decoding transformer to the` relay GIR on picking up of the track relay contacts. However, the relay SIR'is of a type the contacts of which when released pick up onlyv when energy of a particular polarity is supplied `to the relay wind-- ing, and the various parts ofl` the 'apparatus are arranged so that the `energy supplied to vrelay SIR on picking up of the trackl relay contacts is of the wrong-polarity to` pick up the contactsof relay SIR.l

At' this time section 5TV is unoccupied so relay GPC is picked up and the impulse of energy supplied from battery SFB `to the section rails is of normal polarity, and flows from the positive ter-v minalf of the battery over 'front contact 20' of relay EPC, track rail I, back contact l5 of relay GCTMM, winding of relay BWHffrorn left tori'ght, back contact I6 ofrelay SCTMM,'winding ofrelay SWDfrom right to left;k track rail V2, front contact I4 of relay SIR, and front contact 2| of relay SPC to the negative terminal of thebattery SFB.

The impulseofenergy supplied from battery SFB to the section rails lsends energy to relays ISWH` and'SWD in series, and as the impulse of energy is of? normal polarity, it vholds the contacts of-relay6WH1v vin their 'normal position, while it causes# the 'contacts' of relay V6WD to move to their right-hand or reverse position. i

After a short time interval the relay EIR re leases andv cuts off thesupply of energy 'from battery SFB` to the'sectionrails and connects track relay STR across'thevsection rails. During the next picked-up period of the' relays SCTMV the contacts of this=relay to move to their lefthand or normal position, while the energy supvpliedv through the winding of relayBWHfholds the relay contacts in their'normal position. j

On continuedsupply of master code to the'sec tion railsv the contacts vof relay SWD are returned to their normal position each timethat thelfeed-back-impulses is such that each impulse offeedeback energy moves the contacts of relay 6WD to their reverse position.

As a result of code following operation of track relay STR., energy is supplied through the decodingtransformer SDT tov relay 6H; while as the track relay is being operated by energy of 180 code frequency, energy is supplied through the resonant rectier unit I DU to relay 6D, and the contacts of relays SH andi- SD are picked up and' establish the circuit ofthe green or clear lamp G of signal SES which governs movement of traffic from left to right through section BT. The 'resonant rectierunit I BDDU includes-a capacitance and an' inductance which are arranged and proportioned to pass sufficient en'- ergy to pick up the relay 6D when and only when thetrack'relay' STR is operated at the 180 code rate, while the unit includes a rectifier for rectifying the energy 'supplied 'through the unit.

As a result of movement of the contacts of relay 6WD between their two positions, energy is supplied Vthrough the associated decoding trans# former to relay SWDP and its contact 23 is picked upto interruptthe circuitA of the lamps Y and R of signal SWS and to establish the circuitof` the lamp G" of signal SWS which governs movement oft'raic from left to right in section 6T.

At this time the contacts of relay SWH remain inftheir left-hand or normal positions so that energy is not supplied to relay SWHP and its contact 24 remains released.

Operation-of equipment on movement of a train through the track stretch from. left to right When a train moving from leftr to right enters section 5T, relay GPC' releases and changes the energy supplied from battery SFB to the'sect'ion `rails from normal to reverse polarity. On picking up of relay SIR' at a time when relays CTM and `SGTMM are released, energy yflows `from the positive terminal of the'battery overV back contact 20 of relay SPC, front contact I4 of relay SIR, track rail' 2, winding of relay SWD'from left to right, back contact IS of relay SCTMM, winding of relay SWI-l'from right to left, back contact l5 of relay .BCTMM, track rail I, and back contact 2l of relay E PC toy the negati-ve terminal of the battery SFB". The direction of iiow of feed-back energy through the windings ofrelays 6WD and VISWH is such that the contacts of relay 6WD areheld in their lefthand orncrrnal position, while the contacts of relay '5W-H are moved to their right-hand or reverse position.

f On releasev of the contact of relay EIR the supply of energy from the battery SFB to the sectionV rails is interrupted, and the track relay STR'is connected across the Vsection rails,l while on picking up of the relays SCTM and GCTMM an impulse o f master code energy is supplied from 'battery GTB to the section rails in series with the windings offv relays BWH and 6WD. As explained above, the direction of .flow-of this energy through the windings of relays -WH and 5WDV is such as to hold the relay contacts in their normal position; or tomove them to that position if they are not already in their normal position. Accordingly; the contactsof relay VSWH are moved `to ytheir normal position while' the contacts of relay 6WD areheld in their normal position,

Oncontinued operation of the equipmentthe contacts of relay EWI-l are moved to their righthand'position by the feed-back energy 'and are returned' to their left-hand position 'by the master code impulses, while the track relay tTR'. operates inthe Ausual manner to cause energy'to "be sup-- plied through the transformer GDT to relays 6H and 6D. As a result of movement of the contacts of relay BWI-I between their two positions, energy s Ysupplied through the associated transformer to. relay BWHP and its contact 24 picks up, While asthe contacts of relay 6WD remain in their normal positions, energy is no longer supplied to relay GWDP and its'contact 22 releases and interrupts the circuit of the green lamp Gf and establishes the circuit including front Contact 24 of relay GWHP for supplying energy to the yellowlamp Y'of signal EWS. Accordingly', when an eastboundtrain enters 'section 5T, signal BES continues to display its green or clear indication, while the polarity of the feed-back energy supplied over the rails of lsection 6T.is changed so that relay EWDP releases and relay EWI-1P picks up to lthereby cause signal- SWS to display its yellow instead of its green indication.

When the train moving from left to right enters section 6T, the track relay VSTR, isv shuntedand ceases to follow code so energy is no longer supplied to relays 6H and 6D and they release and cause signal BES to display'its red or stop indication. In addition, when track relay STR ceases to follow coda-energy is no longer supplied'to relay SIR and its contact remains released so that feed-back energy is no longer supplied to the track rails and the contacts of relay EWI-I remain in their normal position and relay SWHP releases so that its contact 24 interrupts the circuit of the yellow lamp Y and establishes the circuit of the red lamp R of signal EWS. p I

When the train vacates section T, relay SPC picks up so that on subsequent operation of relay GIR the impulses of feed-back energy supplied to to. pick up the relay 5D. Accordingly, signal GESk now displays its yellow or caution indication.

In addition, on operation of the 'track relay energy is supplied to the relay SIR and it oper- .ates to supply impulses of feed-back energy to the section rails. As relay 6PC is picked up, the impulses .of feed-back., energy are vof. normal polarity and they loperate relay 6WD so that energyis supplied to relay 6WDP and its contact 23 picks up to interrupt the circuit of the red lamp R and establish the circuit of the green lamp G of signal SWS.

--When the train vacates section 1T, relay 1H picks up and transfers control of coding relays liCTM and GCTMM to code transmitter I8OCT vso that energy of 180 code frequency is supplied to the rails of section GT, and onV resultant operation of track relay GTR by energy of 180 code frequencythe relay 6D picks up and interruptsthe circuit cf the yellow lamp Y and establishes the circuit of the green lamp G of signal BES.

Operation of equipment on movement of aA train I through, the track stretch from. right to left When a train moving from right to left enters section 1T, relay,Y 1H releases and changes the energy supplied to section 6T from 180 Yto 75 code frequency and the rate of Aoperation Aof track relay GTR'is reduced so that'relay 6D releases and interrupts the circuit of the green lamp G and establishes the circuit of the yellow lamp Y of signal BES. At this time relay GPC is picked up while relay GIR continues to operate and feed'- back energy of normal polarity is supplied'to the section rails and it causes relay EWDP to be picked up so thesignal SWS displays its green indication.

When the train. advances into section 6T, the track 'relay GTR is shunte'd and ceases to follow code so relay 6H releases and causes signal BES to display lits red indication, while feed-back energy ceases to be supplied to 'the section rails and relay 6WD ceases to operate and relay 6WD? releases to cause signal SWS'todisplay itsfred indication. i I

When the train enters section releases so that on subsequent operation of relay GIR'the feed-back energy supplied'to the 'section-rails is of reverse polarity- When the tran;vacates vrsection 1T,- relay 1 picks up so that coding relays GCTM and BCTMM operate at the cOderate', but as long as section 6T is occupied, the track'relay remain's'released and feed-back energy is not 'supplied over the section rails so that signals EES and `SWS continue to display their stop indications.-

When the train vacates section 6T, the master code of 180 c'ode frequency supplied to the section rails operates the track relay GTR, so that relays 6H and 6D pick up and cause signal GES to dis'- play its green indication, While relay SIR is operated to supply feed-back energy to the track rails. As relay BPC is released, the feed-back energy is of reverse polarity and operates relay 6WH so that relay IISWHP picks up and' causes signal SWS to display'itsyellow or'caution' in'- Y Moamcation shown in Fig. l2 ofthe drawing in series therewith the windings of' -thefrelaysV 6WD and SWH in series.

' In operation, when the -coding relays Y and BCTMM arerboth pickedup, energy is'sup- Y plied from the battery GTBover the circuit which is traced from the positive terminal of the battery to track rail l, through 'the winding of the track relay, not shown, over track rail'z, through winding of relay 6WD from left to right,V and also from rail 2 over front contact 2150i relay GC'I'MM-"and throughwinding of relay SWH'in-multiple' with the windingl of relay 6WD,1ov'er front contact y2l of relay BCTMM and front contact -|1 ofr'relay BCTM to the negative terminal ofthe 4battery I SIB. As master code energy supplied tothe secrrr,y relay tecV In Fig. 2 of the drawing there isfshownf modified arrangement of apparatuswliich we may tion rails'flows through the windings of the relays 6WD and EWH from left to right, the contacts of these relays are moved to their left-hand or normal position, or are held in that position if they are already in that position.

On release of the relays BCTM and BCTMM the supply of energy from battery BTB to the section rails is cut off, While relays 6WD and GWH are connected in series across the track rails over the circuit which is tracedfrom rail I over back Contact 21 of relay SCTMM, through winding of relay GWH from left to right, and through winding of relay 6WD from rightto left. -1 l As the relays 6WD and GWH are connected across the section rails when the relays -GCTM and QCTMM are released, feed-back energy supplied to the section rails may flow through the windings of relays 6WD and BWI-l ,tol operate them. When the polarity of the feed-back energy is such that the positive terminal of the feedback battery is connected to track `rail I, the direction of ow of feed-back energy through the winding of relay 6WD is suchthat the contacts of this relay lare moved to their right-,hand or reverse position,while `the direction of flow of energy through the winding of relay GWH is such that the contacts of this relay are held in their left-hand or normal position.

Similarly, when the polarity of the feed-back energy is such that the positive terminal of the feed-back battery is connected to. the track -rail 2, the direction of flow of energy through the winding of relay 6WD is such that the `,contacts of this relay are held in their left-hand or normal position, while the direction of iiow of energy through the winding of relay BWH is such that the contactsof this relay are moved to their reverse or right-hand position. r

On picking up of the contacts'of relaysGCTM and ECTMM master `code energy is againsupplied through the windings/of relays, 6WD and.6WH to the section rails, and as explained above, this energy moves the contacts of -relays BWI-I or. 6WD to their left-hand or normal position, or .holds them in that position if they are already in their normal position.

Accordingly, the modification shoWninFig. 2 operates so that one or the other of therelays 6WD and BWH is operated by feed-back energy, the one depending on the polarity of the feedback energy, while master code energy vsuppliedto the section rails vrestores to their normal position the contactsk of whichever vone of the relays BWH and 6WD that was operated by the feed-back energy. 1

As a result of operation of relay 6WD or SWH by feed-back energy. the relayV GWDP or.-6WHP is picked up and these relays may control a signal. in the manner explained in connection `with the system shown in Fig. l.

The modication shown in Fig. 2 also operates like that shown in Fig. 1 toprevent false. operation of the feed-backdetector relays by energy stored in the track circuit.

As pointedV out above, when the coding relays. BCTM and SCTMM are picked up, the track battery BTB is connected across the section rails in series with the windings of relays 6WD and GWH inV multiple. At this time :the positive terminal of the battery is connected to ltrack rail I, whilev the negative terminal of the battery is connected over front contact II of relay V.GC'I'M and frontV contact 2B of relay GCTMM to the right terminals of the windings of relays IiWzHV and 6WD so this terminal of the vbattery is connected through the 75 g employed inother ways, as for exampleonaline Winding of relay 6WD .to .trackrail 2, and is also connected through Winding of relay GWHv and front contact 21 of relay GCTMM to track rail 2. Under Athese conditions, energy from the track battery flows. through the windings of relays 6WD and BWI-I from left to right andcauses the contacts of these relays to occupy their lefthand or normal position.

On release of :the contacts of. relay SCTM its contact I2 interrupts the circuit oi relay ECTMM, but .the contacts of relay BCTMM remain picked up for. a short time interval. In addition, on release .of relay 16CTM its contact VI'I interrupts the circuit traced above for supplying energy from the track battery through the windings of relays 6WD andtWH to the track rails, and establishes a circuit to connect the relays 5WD and EWI-I across the track rails so that energy which continues to flow in the track circuit subsequent to interruption of the supply of energy from the track battery .will flow through .the windings ofrrelaysWDand BWH in the direction to maintain. their contacts in the normal position.

YAs pointed-out above, lprior to release of relay GCTM, the positive terminal of the track battery is connected to track rail I, and energy from the track battery Hows through the windings of the relays 6WD and `GWH .from their left-hand to their right-hand terminals andthe relay contacts are moved to their .left-hand or normal position.` When contact I'I of relay GCTM releases and interrupts .the circuit Yof the .track battery, energy in the track circuit due .to inductance of the track circuit or other conditions. continues to flow in the same directionin whichv it had been flowing.V Accordingly, this energy news from track rail 2 through the winding of relay 6WD from left vto right. )and over front contact 23 of `relay BCTMM and back contact. 'Il' of relayr to track rail I. In. addition, energy flows `from track rail 2 overiront contact 2l of relay SGTMM. through winding of relay. EWI-I from left to right, and v over front .contact 28 of relay SQTMM and back contact I'I of .relay BC'I'M to track rail I. Since energy 'stored in the track circuit hows through the windings of relays 6WD and BWH from leitto right, this energy holds the contacts of these yrelays in their left-hand or normal position.

After a short time interval the-relay. ECTMM releases and interrupts the above traced circuit for connecting -relays 6WD and BWH in multiple across the track rails and connects these relays in series across the track rails with the lefthand terminal of the winding oi relay BWH connected tothe track rail I so that relays 6WD and -6WI-I are responsive to dierent polarities of feed-back energy.

`As explained in connection with Fig. 1,..after release of relay BCTM :the relay BCTMM remains picked up for a period long `enough for .energy circuit. Likewise, While in the track circuits illustrated and described the feed-back energy is employed to govern a signal controlling movement of traffic in one direction through the track section, the feed-back energy'is not limited to use for this purpose, and the feed-back energy may be employed to perform any appropriate functions.

Although we have herein illustrated and described only two forms of signaling apparatus embodying our 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 our invention. Y Having thus described our invention, what we claim is:

l. In a coded signaling system, in combination, a pair of conductors extending .between a rst and a second location, a iirst and a secondvpolarized detector relay at said rst location, a coding device having contacts continuously actuated between a iirst anda second position, the contacts of said coding device being eiective when in their rst position to connect a source of unidirectional energy across said. conductors through the windings of said detector relays so that energy supplied from saidlsource to the conductors movesl the contacts of `both detector .relays to their normal position,.the contacts of said coding device being effective when Vin their second position to connect said detector relays across said conductors in such manner that the contacts of one of said relays are moved to their reverse position by energy of one polarity and so that the contacts of the other of said relays are moved to their reverse position by energy of the other polarity, a coderfollowing relay at said second location-operated by energy supplied oversaid conductors from said'rst location, means at said second location for supplying to said conductors during the intervals between the irnpulses of energy supplied to said conductors at the rst location energy which at times is of one polarity and at other times .is ofv the other' polarity, signaling means governed by said code following relay, and signaling means governed by said detector relays. Y v

.2. In a coded signaling system, in combination, a pair of conductors extending between a rst and a second location, a first vand a second polarized detector relay at said iirst location, a coding device having contacts continuously actuatedv positions, the contacts of said coding device being effective when in their second position to connect said detector relays across said conductors insuchmanner that the contactsof one of said relays are moved to ltheir reverse position by energy of one-polarity` supplied over said conductors and so that the contacts of the other of saidrelays are moved to their reverse position by energy of the other polarity supplied over saidconductors, a code following relay at -said second location operated by master code energy suppliedv over said conductors. means at saidY second location for supplying impulsesv ofV feed-back energy to said conductors in the intervals between the impulses of master'code, means for causing the feedback energy to be of one polarity at times and to beof the other polarity at other times,

signaling means governed by said code followingl relay, and signaling means governed by said detector relays. Y

3. Ina coded railway signaling system, a sec-:- tion of railway track, a iii-st and a second-polarized detector-relay at'one end of said track section, a coding device having contacts continuously actuated between a rst and a second position, the contacts of said coding device be-. ing eiiective when in their first position to conneci-l a source of unidirectional energy across the rails of said vtrack sectionthrough the windings of said detector relays so that an impulse of mas-v ter code-energy issupplied to the section rails and the contacts of said detector relays are caused to occupy their normal position, the con'- tacts of said coding device being effective when in their second position to connect said detector relays across said track rails in such manner that the contacts of one of said relays are moved to their reverse position by energy of one polarity supplied over the track rails and so that the contacts of the other of said relays are moved to their reverse position by energy of the other polarity supplied over said track rails, a code following track relay at the end of said track section remote from said detector relays and'operated by master code energy supplied over the section rails, means associated withfsaid trackV relay for supplying impulses of feed-back energy to said track rails in the intervals between the `impulses ofA master code, means for causing the feed-back energy to be of one polarity at times and to be of the other polarity at other times, signaling means governed by said track relay, and signaling means governed by said detector relays. Y

4.' In a coded signaling system, in combination,l

a pair ofconductors extending between a rst and a second location, a first and a second codingdeviceandza first and a second polarized relay atf said .first location, each of saidcoding devices having contacts movable between a rst vand la second position, a circuit effective when the con-v tacts of both .of said coding devices' are in their rst position to connect a source of unidirectional current across said conductors through the windings of saiddetector relays so Ithat en-` ergy supplied through said relay windings moves the relay contacts to their normal-position, a circuit eiective when the contacts of'said second coding device are in their second'position to con-r nect said detector relays across said conductors so that the contacts of'one of said relays Yare moved to their reverse position by energy of one' polarity supplied over saidconductors and the contacts of the other of vs-aid relays are moved to their reverse position by energy of the-other l polarity supplied over said conductors, a code following relay at said-second location operated by ,energy supplied over said-.conductors froml said rst location, means at lsaid-second locationY I for supplying energy .to said conductors in the intervals between impulses of venergy supplied to said conductors at said'rst location, means for causing the energy supplied tosaid yconductors at said second location to be of vone polarityl attimes and of the otherv polarity at other times,l

second. position and for thereafter movingl the` contacts of the second coding device to their second position, whereby there is aitime .interval `between in-terruptionof thesupply of energy to said. conductors-at said first location and connection of saiddetector .relays across. said conductors. and energy storedv in thecircuit ofV said conductors will be dissipated beforesaid detector relays are' connected across said conductors, signaling means governed. by said vcodefollowing relay, and sig nalingmeans governed by said detector relays. i

.-5. `In a coded signaling system, .in combination, a pair of conductors extending between a first and a second location, a first and a secondcoding device and .a first and a second polarized relay at said firstlocation, each V,ofsaid coding devices having contacts movable between aiirstV and a second position,:'means.for moving the contacts of both of said coding devices to their rst position and for moving the contacts of the rst codingdevice 4to their second Aposition and for thereafter moving the'contactsof said second coding `device to their second position, means effective .when the contacts of both of said coding. devices are in? their first .position to connecta source of unidirectional current acrosssaid con'- ductors through the'windingsv of said detector relaysrin series .so that energy supplied through the windings `of said detector relays causes the relay contacts to occupy! their znormalposition, a circuit effective when the contacts of Saidsecond coding device are inftheir second position yto connect said .detector relaysacross'said conduc-l tors so that the contacts of one of said relays are moved to their reverse position by energy of onel polarity Vsupplied oversaid conductors and the contacts of the other rof'saidrelays are moved to .their -reverse position by energy of the other* polarity supplied over said conductors, a code following relay at the second'location operatedI by energy supplied over said conductors from the first location, meansat' the second location for supplying energy tof said conductors in the intervals `between thev impulses of energy supplied to the conductors at the rst location, means for causing the energy supplied to said conductors at said second location to be of one polarity at times and of the other polarity at other times, signaling means governed by said code following relay, and signaling means governed by said detector relays.

6. In a coded signaling system, in combination, a pair of conductors extending between a first and a second location, a first and a second coding device and a first and a second polarized relay at said first location, each of said coding devices having contacts movable between a first and a second position, means for moving the contacts of both of said coding devices to their rst position and for moving the contacts of the iirst coding device to their second position and for thereafter moving the contacts of said second coding device to their second position, means effective when the contacts of both of said coding devices are in their rst position to connect a source of unidirectional current across said conductors through the windings of said detector relays in multiple so that energy supplied through the windings of said detector relays causes the relay contacts to occupy their normal position, a circuit eiiective when the contacts of said second coding device are in their second position to connect said detector relays across said conductors so that the contacts of one of said relays are moved to their reverse position by energy of one polarity supplied over said conductors and the contacts of the other of said relays are moved to their: reverse .position .by energy lof .the other polarity .supplied over .said conductors, .acode following vrelay at the second. locationoperated byienergysupplied .over said conductors fron the .rstlocation means. at the second. locationfor supplying energy .to said conductors inthe intervals vbetween the impulsesof energy supplied to'zthe .conductors at the first location, means' for. causing the energy suppliedto' said conducl* torsat said second location to be ofone'polarity at times andof the Votherfpolarity. at other tim'e`s,`- signaling means governed by said code following relay, 'and signaling meansgoverned by said der.1 tector relays. A y f 7. Inl ak coded .railway signaling-system, a-sec-E tion of. railway track, a rstand asecond polar-- izeddetector relayatl one Yend of said track sec# tion, a coding device having contactscontinu' ously actuated between a iirst-and a second 'position, `the contacts `of said-coding device being' effective when in their rst position' to connect a source of lunidirectional energy across lthe railsof said'track section throughl the windings" of said detector relays in series so`that anfimpulse of master code energyl isf supplied to the'se'cti'on' rails andthe contacts of said detector relays are caused to occupy their normal position, the com" tacts ofsaid .coding Vdevice being effective when in their second position -to connect said detector relays across said track rails in such manner thatI thezcontacts vo-one of said'relays 4are "movedl td' theirA reverse-positionby energy-of one polarity supplied overthe track rails anclso thatthe con'I tacts of the-other ofsaid`relays are'movedto" their reverse position'by'fenergy'of the other.'l polarity supplied over said trackVV rails, a codev fol-Y lowing track relayfat the end of `said track sec:-` tion remote fromsaid detector relays 'and operaL a-ted'bymaster code energy'suppliedover'the section rails, means associated with said track relay for supplying impulses'of feed-back energy to said'track rails in the intervals'betweenthe impulses of master code, means for causing the feed-back energy to be of one polarity at times and to be of the other polarity at other times, signaling means governed by said track relay, and signaling means governed by said detector relays.

8. In a coded railway signaling system, a section of railway track, a first and a second polarized detector relay at one end of said track section, a. coding device having contacts continuously actuated between a first and a second position, the contacts of said coding device being effective when in their rst position to connect a source of unidirectional energy across the rails of said track section through the windings of said detector relays in multiple so that an impulse of master code energy is supplied to the section rails and the contacts of said detector relays are caused to occupy their normal position, the contacts of said coding device being effective when in their second position to connect said detector relays across said track rails in such manner that the contacts of one of said relays are moved to theiry reverse position by energy of one polarity supplied over the track rails and so that the contacts of the other of said relays are moved to their reverse position by energy of the other polarity supplied over said track rails, a code following track relay at the end of said track section remote from said detector relays and operated by master code energy supplied over the section rails, means associated with said track relay for supplying impulses of feed-back energy to said actuated betweenga first and a second position,`

the contacts of said coding device being effective when in their first position to connect a source of unidirectional energy across therails of said track section so that an impulse of master code energy is supplied to thesection rails, the.con tacts of said coding device also -being effective when in their first position to cause to be supplied towindingsof said detector relays energy eiective to cause the contacts ofY said detector relays to occupy their normal position, the contacts of said coding device being eiective when in their second position tov connect said detector relays across said track rails in such manner that the contacts of one of said relays are moved to their reverse position by energy of one polarity supplied over the track rails and lso that the contacts of the other of said relays are moved to their reverse position by energy of the vother polarity supplied over said track rails, a code following track relay at the end of said track section remote from said detector relays and operated by master code energy supplied over the bsection rails, means associated with said track relay for supplying impulses of feed-back energy to said track rails in the-intervals between the impulses of master code, means for causing the feed-back energy to be of one polarity at times and to be of the otherpolarity at other times, signaling means governed by said track relay, and signaling means governed by said detector relays.

, 10. In a coded railway Vsignaling system, in

combination, a first anda second coding devic and a first and a second polarized detector relay at one end of said track section, each of said coding devices having contacts movable between .a rst and a second position, means riormoving the contacts of both of said coding devices to their irst position and for moving the-contacts of the iirst coding device to their second .-position and for thereafter moving the contacts of said second coding device to. their second position, means effective when the contacts of both of said coding devices are in their first position to connect a source of unidirectional energy across the rails of said tracksection so that animpulse of master code is supplied to thesection rails, means eiective when the contacts ofy 'both of said coding devices are in their first position to cause Y to'be supplied to windings of said detector relays energy effective to cause vthe contacts of said de.- tector relays .to occupy their normal positions.

means effective when the 'contacts of said coding devices are in their-second position to connect said detector relays acrossy the track rails in such manner that the contacts of one of said relays are moved to' their reverse position vby Y energy of one polarity supplied over the track rails and so that the contacts :of the other of said ree lays are moved to their reverse positionby energy of the other polarity supplied Aover saidftrack rails;

a code following track relay at the end of said track section remote from said detector relays andV operated by master code energy supplied over the section rails, means associated with said track relay for supplying impulses of feed-back energy to. said track rails in the intervals between the impulses of master code, means for causing-the feed-