US2364840A - Railway signaling system - Google Patents

Description

Dec. 12, 1944. w. F. ZANE EIAL RAILWAY SIGNALING SYSTEM Filed July 18, 1941 5 Sheets-Sheet l INVENTORS I amifZme and GevzgelllBau lzpzm.

THbYH ATTORNEY Dec. 12, 1944. w. F. ZANE ET AL RAILWAY SIGNALING SYSTEM Filed July 18, 1941 3 sheets-Sheet 2 ww ww Inn $4 pq 'uun INVENTORS lUzZlzamEZaneand g w- Z 4 THEIR ATTORNEY 5 Sheets-Sheet 3 INVENTORS l'lliamFZcme and B yGeorgelflBaufbman THHH ATTORNEY Dec. 12,1944. w. F. ZANE ETAL RAILWAY SIGNALING SYSTEM Filed July 18, 1941 under the customary control of switches.

Patented Dec. 12, 1944 UNITED E15 PAT ENT OFFICE.

2,364,840 RAILWAY SIGNALING" SYSTEM. 7

William. Zane, La- Grange, 111;, and George.

Baug-hman;v Swissvale, Pa., assignors to. The Union Switch and. Signal Company, Swissvale, 2a., a corporation. of Pennsylvania 3 Application Jilly 18, 1941', Serial No." 402-,9'06

i Claims. (01.246-33 Our invention relates to a railway; system adapted for use in track stretches where trafiic moves in both directions over a; single track.

It is an object of our inventionto provide an improved signaling system in'which the signals controlling both" directions of'trafiic' are governed byasingleline circuit.

A further'obj'ect of ourin'ventibn is to provide an improvedsystem' of the type described which employs coded energygin the'linecircuits and which is arranged so that a cross betweenthe linewires will not producea falseclear signal.

Another object of our invention is to provide an improved signaling system of the type described.

We shall describe twoforms-of' railway' signaling system embodying our invention, and" shall then point out the novel features thereof in claims. i

In the drawings,

Fig. I is adiagram consistingofFigs. IA and 1 13 and showing a stretch of railway track equipped with one formof signaling system embodying our-invention, and i Fig. 2' is a diagram consisting of Figs. 2A and 2B and showing a stretch of railway track equipped witha modified form of signaling system embodying our invention.

Similar reference characters refer to similar parts in both views.

Referring to Fig. I of the drawings, there is shown therein astretch of single track railroad over which traflic moves in both directions. To facilitate description of the equipment it will be assumed that the right-hand end of the track stretch is east and that the left-hand end thereof is west. I The track. stretch includes passing. sidings which are located at appropriate intervals and permit traffic to be diverted from the main track Two such passing sidings are shown and are designatedXandY.

The rails I and" 2 of the track stretch are divided by insulatedjoints 3 into'track sections designated 2T, 3T, 4T, 5T, etc. Each of the track sections is provided with a track circuit including a track battery connectedacross the section rails at one end of the section, and a track relay, designated TR with a suitable prefix, connected across the section rails at the other end of the section.

Eastbound trafiic through the track stretch is governed by a plurality of trackway signals desthrough the trackstretch is governed by signals designated 1S, 5S and 35., The signals shown are of the color light type, but-it" should be 'un'- derstood' that the invention is not limited to the use' of signals of this type andthat any appropriate form of waysides'ignal well'known. in the art may be employed. Eachof these signals, has a green or: clear lamp G', a" yellow or" caution lamp Y, and a red or..stop lamp. R. The signals 88 and 38 at the entrancejen'ds of the passing sid ings have'upper portions'whi'ch includ'ethe green, yellow and: red lamps as illustrated in the drawings, while these psigrialsmay'also have low'er portions, not shown, governing movement of trains from the main track onto the passing sidin'gs. i. j L

The diagram which forms the drawings shows the means for controlling thessignals 4S, 58,, 6S and 18;. The means for controlling thesignals 3S and B'S'is not aipartofv this. inventionand has not been shown, and these signals may be controlled in any appropriate manner well known in the art.

In most cases the contacts associated with each relay are shown in the drawings directly under the relay winding. However, in, a few instances no energy is supplied.

ignate'd 48, BS and 88, while westbound traffic.

the relay contacts are separated from the relay winding, and where this is done. the relay with which the contactis associated is indicated by appropriate reference characters located-directly above the contact.

In the system provided by this invention the signals 48 and: 58. are controlled over a line cir.-.-

cuit J which includes line wires. 20' and.2|, "whil1e' signals 6S and 1S are controlled over a line circuit K which includes. linewires Hand-23;

Each signal location is provided; with a suitable sourceof direct current such as. a storage battery, not shown, the terminals. of which are designated B and C. y i

The equipmentisshown in the condition which it assumes when the track stretch is vacant. At this time the coding relay JCR'Li's. supplied with energy of 180 code frequency fromv a code transmitter ICT over a circuit which includes front 7 contact 25 of relay 3TB. This, energy consists of energyimpulses a minute which are-sepa rated'by periods of equal duration during which When. the coding. relay JCR 'contacts 26 and 21.,establish a circuit tosupply impulses of master code. energy to the line circuit J At this time. as sections 2T and 31 is. picked up, its

through front contact 28 of relay 3D and front contact 26 of coding relay JCR to line wire 20, while terminal C is connected through front contact 29 of relay 3D and front contact 21 of coding relay JCR' to line wire 2| so that the master code supplied to line circuit J is of normal polarity.

This master code energy is supplied over the line circuit and through back contacts 30 and 3| of impulse relay JIR to line relays SP and EN.

The line relays 4P, P, GP and IP are of the stick polar type having contacts which are moved to their normal positions, as shown, on the supply of energy of normal relative polarity to the relay winding, and to their other or reverse positions on the supply of energy of reverse relative polarity to the relay winding. The contacts of these re lays when moved to either position remain in that position until the relay winding is supplied with energy eifectiveto move the relay contacts to their other position.

- The line relays 4N, 5N, 5N and IN are of the biased polar type and respond to flow of energy in the windings thereof in one directiononly.

The polar line relays P control the connection from the line circuits to the line relays N so that if the contacts of the polar relays respond to changes in the polarity of the current supplied to the line circuits, the relays N will be connected with the line circuits in such manner that energy 'will flow in the relay windings in the direction effective to pick up the relay contacts.

The arrangement of the relays P and N is not the tw portions of theprimary winding of de-,

coding transformer EDT are alternately energized and energy is induced in the secondary winding of this transformer. The energy induced in one of these secondary windings is supplied through the resonant rectifier unit 5RU to the relay. 5H. 7

The unit RU is constructed in the manner well known in the art and is arranged so that it passes sufiicient energy to pick up. the relay 5H when and only when the relay 5N. is responding to energy of 180 code frequency.

As contact35 of relay 5H is picked up and as contact 36 of relay SP is in its normal position, the circuit of the green lamp G of signal 58 is complete and this lamp is lighted so that the signal 58 provides its green or clear indication.

The energy induced in the other secondary winding of the transformer EDT is supplied to the impulse relay JIR. The relay JIR is of a type which responds to energy of one polarity only and the various parts of the equipment are arranged so that energy of the polarity efiective to pick up thecontacts of ,the relay JIR is supplied to 'the relay on release of the contacts of relay. 5N.

Accordingly, during the supply of an impulse of master code the contacts of relay JIR are released, While during the off periods in the master code the contacts of relay JIR pick up to disconnect the line circuit from the relays SP and 5N, and to establish a circuit to permit impulses of feed-back energy to besupplied to the line circuit. The contacts of relay JIR when picked up remain picked up for a, short time interval, but become released and reestablish the circuit of the relays 5P and 5N before the start of the next on period in the master code.

When the contacts ofrelay JIR are picked up, a circuit is established to supply an impulse of feed-back energy to the line circuit J As sections BT and IT are unoccupied, the relay SE is picked up so that the impulse of feed-back" energy is of normal polarity.

At this time terminal B is connected through back contact '38 of relay 58R, front contact 39 of relay BTR, front contact 40 of relay 6H, and front contact 30 of relay JIR to line wire 20, while terminal C is connected through front contact 42 of tact of the relay 4N rectifies the energy supplied from the secondary winding of transformer 4DI t relay 41-1. As a result, contact 44 of relay 4H is picked up and establishes the circuit which includes normal polar contact 45 of relay 4P for supplying energy to the green lamp G of signal 4S so that this lamp is lighted and conditions signal 48 to provide its green or clear indication.

From the foregoing it will be seen that when the track stretch is vacant, master code energy of positiveor normal polarity and code frequency is supplied to the west end of the line circuit J and conditions signal 58 to provide its clear indication, while during the off periods of the ;master code impulses of feed-back energy of positive or normal polarity are supplied to the east end of the line circuit and condition signal 48 to provide its green or clear indication.

The equipment for controlling signals 68 and 7S operates in the same manner as that for controlling signals 4S and 5S, and as the track stretch is vacant, signals 6S andflS are conditioned to provide their green or clear indications. At this timemaster code energy of 180 code frequency and normal polarity is supplied to the east end of line circuit vK, while feed-back energy of normal polarity is supplied to the west end of line circuit K. Theoperation of this equipment is substantially the same as that associated with line circuit J and a detailed explanation of its operation is unnecessary.

Operation of equipment on movemenrt of a train through the track stretch For purposes of illustration it will be assumed that an eastbound train passes through the track stretch. When this train enters section 2T, track relay 2TB, releases and interrupts the circuit of relay 3D so that its contacts 28 and 29 release and change the master code supplied to line circuit J from normal to reverse polarity. This causes the polar contacts of relay 5P to shift to their reverse positions so that contact 36 interrupts the circuit of the green lamp G and establishes the circuit of the yellow lamp 'Y of signal 5S. This will warn a westbound train of the approach of the eastbound train.

On this change in position of the contacts of relay 5P the connections from the line circuit to asefac'eo' relay N are changed so that eventhough=the polarityof the energy suppliedto the line circuit J 'is-reversed, energy continues to flowln" the same direction through the relay; winding. Accordingly, therelay'SNcontinues to follow code sothat energy is supplied through the decoding transformer 5DT to the relay 5H and to tlie'impulse relay JIR. Ifhe relay 'JIR, therefore, continues to cause impulses'oi feed-back energy of normal polarity to be'supplied to the'line circuit .1 so'that signal is continues to provide its green or clear indication. i

As relay 5H remains picked up, the "feedback energy supplied to line circuit K continues tube of normal polarityrand signal 18 continues to; display its green or clear indication.

When the train advances intosection 31, track relay 3TH releases and it contact interrupts the circuit for supplying energy of 180 codefrequency to the coding relay- JCR and establishes a circuit including back contact l1 of' relay 33R for supplying energy of 75 code frequency" to the coding relay JCR. .AS a result; thecontacts 26 and 21 of relay operate at-the lower frequencyand master code energy of 75 code frequency. is supplied to the line circuit Jtso' that relay-5N -iollowsthis code and causes the relay 'JIR to supply feedeback energy toathe. line circuit to maintain the display of the iclear indication b signal 48.. V y

Whenrelay 5N is following energy of 75 code frequency, too little energy is supplied through the resonant unit-iRU'to pick up the relay 51-32.

This relay, therecre,zreleases and Jitsi contact 35 establishes the circuit 'otthe red or stop lampiR. oiv signal 58, while its contacts 48 and. 49 cut on? the supply of "feed-back energy" to line circuit K as contact 32 of: relay 5SR;is released. rThls relay for supplying -direrational stick relay 38R, and when the contactsofthis relay'pick up, its contact i l establishes a 'circiut 'to'manitain the relay energized-aslo ge track -relay3 I'R, is released When the contacts'oi relay 38R. are picked up,-its contact I 1 interrupts the supply oi'energy of 75 code frequencytothe coding relay 'JCR whlle its contact establishes the circuit to supply energy 180 code frequency to this relay. The change iii-the rate of operation of relay JCR iswithout consequence; however; as

long: as section'fiIor 5T is'oc'cupied'since master code. is prevented vfrom being supplied over the line-circuit when. these sections are occupied. 1

When the train advances into section 51?, track :relay' S'IR releases andi'its contacts 58 and interrinit': and. short circuit 'the line circuit J.

. At this time fmaster code-energy oflfld code frequency and normals polarity" continues torbe supplied :toxthe east. end line circuit K. so that signal is: continues'toeprovide itsxgreen :or

clearindication'. V,

. In addition, on release-cf relay STR its: contact 53" releasesbut because cizthe prior release 10f contact, .62' oftrelay 5H:the-pick+up circuit ofrelay 58R is not established and: contact 63 ofthis relay 'remains'released;

"When the trainrenters section 6T, track relay 811R releases. and cuts nil-the supply of master causes relay 'IHatO release so thatitscontact Bl establishes the circuit of the red lamp R (ii-signal TS to thereby; prevent a. westbound Ztrairr from advancing beyond signallS.

When the train-adyances into section 41; track relay 4TR releases and its contacts 52 and-53 interruptthe line circuitJ, andthereby prevent the supply of energy to line relays JP and 4N, andalsotorelaysiP and 5N.

" Accordingly,- relay GN' releasesand energy code energyto relays-6P and:N, whileit also prevents the supply: of ffeedebackfr energy'tothe line-circuit'K. hIn addition, on release of track relay 6TB; its contacts short circuit the; portion of. line circuit K associated line relays; 1F

and IN to prevent improperenergization of these relays as'explainedabovey is no: longer supplied through the decoding trans.- iormefSDTand thevresonant unit BRU to relay 6H, and this relay-releases and its contact '64 signal 6S. 7

establishes the circuit of the red-IlampRrof The relay BH-isisomewhatslow'in releasing and a its contactsremainv-pickedupforaacperiod sub- When the supply of master code to line circuit J is interrupted, relay-5N ceases to follow code and energy is no longer supplied to relay JIR so that this relay ceases to operate andiimpulses of "feed- In addition, on release of the contacts 52 and a 5-3 of track relay-4TB they short circuit "the portion of the line circuit which isoconnectedto line relays Panel 4N during the 'releasedperindsof the contacts 26 and zlr-of coding relay JCR. As

this portion. ofthe line circuit is short circuited there is tic-possibility that. the relay 4N will be energized if, because of across or: other-condition, energy is improperly supplied tothis'p'ortion of the line circuit. Therelay 4N, thereiore, remains released and energy is not supplied through the transformer IDT to relay! so that relay AI-I'will remain released and maintain the display of a stop indication by signal: 48.

- .On release of relay 4TB its contact 55' com pletes the circuit including baclccontactiis of sequent :to release of the contactsof: relay 6TB. As. a result on entranceof a train into section 6T; itraclc relay liTR'releases and" its contact 65 establishes a pick-upcircuit ior relayiSR. This circuit includes front contact of relay 'GH.

soon as relay 68R picks up; its contactBG establishes a stick circuit 'for, energizing the relay after release of relay EH; :When rreiay liSR'v is picked up, its contact it permits supply of feedback" energy of reverse polarity-to the line cir-' cuit J while'relay 6H is-released; while. contact 68 .01? relay 68R prevents the supply of: feedback energy to line circuit Kt When the train advancessinto section TI; track relay t'IR releases andfladditionally interrupts and: short circuits line'circuitK.

When the trainvacates section 3T, 7 track relay 3TB picks up and-itscontact 56=intzerruptathe circuit of the relay 3SR'.so,'that thisrelayreleases,

while contact-25 0f relayTl-R: establishes a circuit tonsupplyuenergy of code-:trecuencyto the coding relay JCR. y e In addition, when-relay 3TR-picks up the c'irv cult of the-relay 3D complete and the contacts 28' and 29 of this: relay'picl; up so that the. mas

ter code: supplied to the line circuit 'Jis. again: of 180 code frequency and normal rel'ative polarity.

when the: train advancesiar enough to vacate sections 4.1" and ST; line circuit J is againcomplete and the: maste code supplied to-the line circuit feeds to the line relays SP and 5N and 1 signal 5Sis again conditioned to provide its green or clear indication.

contact 69 of relay 8D.

Asa result of code following operation of relay 5N, impulses of energy are supplied to relay JIR.

At this time relayGH is released, while, as xplained above, relay BSR is picked up. As lon When the train advances far enough to vacate section 6T, relaylBTR picks up and it contact 39 establishes the circuit for supplying impulses of feed-back energy of reverse polarity to line circuit J. At this time terminal B is connected through back contact 38 of relay 58R, front contact 39 of relay BTR, back contact 40 of relay 6H, and'front contact 3| of coding relay JIR to line .Wire 2|, while terminal 0 is connected through tact 11 of relay GP to light the yellow or caution lamp Y of signal 68.

cause the green or clear lamp G of signal to be lighted;

On picking up of relay BI-I its contacts 40 and 42 change the ffeed-ba ck energy supplied to line circuit J from reverse to normal polarity. On

back contact 42 of relay 6H, front contact 61 of I relay GSR, and front contact 30 of relay J13 to 1 line wire 20. As a result of the supply'of feed back energy of reverse polarity to line circuit J,

the contacts of relay 4P are shifted to their right- -hand or reverse positions, while energy is supplied through the decoding transformer 4DT to relay 4H so that its contact 44 picks up and cooperates with reverse'polar contact 45 of relay 4Nto light the yellow or caution lamp Y of signal 68.

, When the train advances into section 8T, track 1 relay BTR- releases and interrupts the circuit of 3 relay 8D so that its contacts 69 and 10 release and change the polarity of the master code en ergy supplied to line circuit K. g In addition, on release of track relay 8TB its contact ll completes the pick-up circuit of relay 1 88R. This circuit also includes back contact 12 p of track relay I'IR, while, when relay 8SR picks up, its contact [3 establishes a stick circuit to i maintain the relay energized as long as track 1 relay BTR is released.

On release of track relay 8TB its contact 14 1 interrupts one circuit for supplying energy of 180 code frequency to coding relay KCR, while contact 16 of relay 8SR establishes another circuit to supply energy of this code frequency to this relay. Accordingly, the coding relay KCR continues to operate at the 180 code rate.

Similarly, when the train advances into section 1 9T, track relay 9TB. releases and interrupts the circuit of relay 8D to maintain it released.

When the train advances far enough to vacate section 1T, track relay ITR picks up and completes line circuit K so that master code of 180 code frequency and reverse polarity is supplied over the line circuit to the line relays GP and 6N. The energy supplied to the line circuit is of reverse polarity as relay 8D is released and terminal B of the source is connected to line Wire 23 i through back contact 10 of relay 8D, while terminal C is connected to line wire shift to their reverse positions, while relay 6N follows the code and energy is supplied through the decoding transformer 6DT and the resonant unit BRU to pick up the relay 6H. Accordingly,

the contact 64 of relay 6H interrupts the circuit In addition, on release of track relay 8TB the f signal BSis conditioned by means not shown to display its red or stop indication.

this change in the polarity of the feed-back energy supplied to line circuit J the polarcontacts of relay 4P are shifted to their left-hand or normal positions and contact establishes the circuit of the green or clear lamp G of signal 48.

When'thetrain advances far enough to vacate section 8T, track relay 8TB, picks up and its contact 1| interrupts the circuit of relay BSR, while :its contact 14 establishes a circuit to maintain code supplied to line circuit K from reverse to normal polarity. On this change in the polarity of the master codesupplied to line circuit K the polar contacts of relay 6P are shifted from their reverse to their normal positions and contact 11 establishes the circuit of the green lamp G of signal 63. At this time'there is no change in the polarityof the feed-back energy supplied to line circuits J and K so that signals 48' and .15 continue to 'display'their green orclear indications. g

The operation of the equipment onmovem ent of a Westbound train through the track stretch is substantially the same as for movement of an eastbound train through the track stretch and a detailed explanation thereof is unnecessary.

It Willbe seen also that when the track stretch v is vacant, .master code energy of 180 code frequency and positive or normal polarity is supplied to each line circuit at the end thereof adjacent the headblock signal to control the intermediate signal, while feed-back energy of positive or normal polarity is supplied to the line circuit at the end thereof adjacent the intermediate signal to control the headblock signal;v

When a train enters the overlap section at the leaving end of a passing siding, the master code supplied to the adjacent line circuit is changed from 180' code frequency to code frequency.

This energy is not effective to control the intermediate signal so thissignal is caused to display its stop indication, but this energy causes feed- From the foregoing "it will be seen that the' .invention is directed to use on single track back" energy tov be generated so thatithe headblock signal in frontof thetrain continuesto display its clear indication In additiomonthis the display of a .clear indication by the intermediate signalin front of'the train,

When the train passesthe intermediate signal, the other line circuit is interruptedso that the intermediate signal is placed at stop. -When-the train vacates the stretch in; the rear of the intermediate signal,;.fmaster.-; code-of 180 frequency is again supplied over the line circuit associated with that signaland causestheintermediate signal for the opposite directionof traffictoagain display its'clear indication. The supplyof feedback energy to this line circuit continues to:be cuton until the train -.vaca tes .the tracksection in advance of the mtermediatewsignal so-Zthat the headblock signal in the reart-of: the "trainicontinues to display its stop indication. 1

When the train doesyacate thetrack section in advance of the intermediate vsignai, feed-- back energy of reverse polarity. issupplied to the line circuit in the rear. of the intermediate signal so that the ,headblock signal ;in the rearof th train displays its caution indication;

When the train advances-beyondthe signallat the entrance end of :the nextpassiug siding and vacates the section :in'the rear of zthiscsignal, master code of 180 codefrequency and reverse polarity is suppliedvover theiline circuit totcon dition the intermediate, signal inthezrearzot the train to display its caution signal,.-,and:to-.ca11se the feed-back energy suppliedto the other: line circuit to be changed fromzreversetoxnormal polarity and thereby cause .the.unification. dis- .played by theheadblock signal in:thesrear of that intermediatesignalto be changedfrom'cam tionto clear. .In addition; at thisxtime teed .back energy of normalpolarity'isl supplied over the line circuit immediately in the rear ,of "the train to. condition the headblockrsignalin the rear of the train and controlling \traffic .in the oppositev direction to display itssgreen or. clear indication.

Construction of modification shown in Fig. ,2 In Fig. 2 of the drawings thereis ishown-a modified form at signaling system which may be employed in place of that shown in Fig, 1.1 The system shown in Fig. 2 is similar torthatshown in Fig. 1, but difiers therefrom .inthat. thecode transmitters are located at the: intermediate sis? nal locationinstead of .at thesheadblock signals. Accordingly, in the system shown in Fig.2 fmaster code is supplied from the intermediatesignals to the headblocksignals, whileffeedeback energy is supplied in the.opposite.direc'tion-..

The modification shown-in Figtz, .likethat shown in Fig. 1, employs master 'codeiof two codev frequencies, while theequipment at the headblock locations :is arranged fSQ .thatit will respondto only Qnepf thesefrequencies to;c0n I dition the associatedrsignalto display a proceed signal to display a proceed indication. a

indication. However, master? code of either frequency will cause feed-back energ'yto be developed. and thereby. cause the intermediate In the drawings showing the system of 2 most of, the relay contacts are shown directly below the relay windings, .but in. some instances the contacts-are shown separated from the windings. Where this is done, the relay with which thecontact is associatedis' indicated by app-ropriate.reference characters locateddirectly above the contact.

The equipment of Fig. 2 is shownin the condition which it assumes when the trackstretch circuits J and K. i

is vacant. At thisvtime the trackrelays ar all picked up andline '{circu its J and K are both complete. a

Atthis time energy of 180 code frequency is suppliedto the coding relay JCR over the circuit which is traced. from terminalB through the contact of code transmitter I80C?I ,,f ront contact 1 no of relay 15H, front contact 401 l of track relay 6TH, and back contact I0? oi relay 58R. .Inlike traced from terminal B through the contact .of

code transmitter IBOC'I, front contact I05 of-relay 5H, front contact I06 of trackrelay 5'IR,-.and'

back contact I01 of relay-8BR. Accordingly, the coding relays JCR and KCR operate to supply master code oilBOpode irequencyto the line As. the relays 6H andiiH are picked up, the master codes are of normal polarity so that signals 43 and 1S] are both; conditioned to provide their green or clear indications. I

As a result of code followingoperation ofthe relays 4N and 1N,.impu1sesofenergy are supplied to the impulse relays JI R .andKIR and these relays operate to cause impulses of feedback energy to'be supplied to the line circuits J and K. .As. the'relays ,3D .and BD are picked up, the freed-back energy is cfnormal polarity 'When an eastbound train i enters ,sectiondiT, track relay ZTR releases and interrupts the cir'-.

cuit of relay 313 so that relay '3D releasesand changes the polarity of the feed-back; energy supplied to line circuitJ from normal to reverse.

. On this change in the polarity 01" the feedback energysupplied .tojline' circuitJ the con- -tacts of relay 5P are shifted totheir reverse position and cause signal5S to display its yellow or caution indication. At {this tirne.,.rela y 15H remains picked up.andmaster "code oinormal polarity continues to be supplied to,1 in circuit Kso that signal IS continues ,to provide its green or clear indication.

When thetrain a amant SeQtionf3T.1,track relay 3TB. reieases and' its contact ,lljn interrupts the circuit. forhjsupplying feed back3 energy to line circuit.J i so that relay, 5H;releases andilig'hts the redorstop lamp Br f ,signal.;5.s:.' .Inaddition, on release of. relay 5H" itslcontacts .H' II and H2 change the polarity oi the mast'efcode supplied to linecircuit Kirom normal toreverse polarity; whi1e...as.-a result of the release of con:- tact I05 ofrelay liiH the "fmaster. codesupplied to line circuit Kishhanged irldm 180.1:0 .120 code frequency. The circuit for vsutnolyingQenergy to the coding relay,KCR. is traced from B through the contact of code transmitter I'ZU C'I back contact H4 of relay 58R, back contact I of relay 5H, front contact I06 of relay 5TB, and back contact l0! of relay GSR.

On this change in the frequency of the mas-i ter. code supplied to line circuit K insufiicient energy is supplied through the resonant unit TRU.

to keep relay 1H picked up and this relay releases and causes signal is to display its redor stop indication to therebyprevent a westbound train from advancing beyond the passing siding Y.

Th master code of 120 frequency sup-plied over line cir'cuitK causes feed-back energy to relay 4TB. releases and its contacts interrupt line circuit J to thereby cut off the supply of mas Accordingly, the master code supplied to line ter code over this line circuit to the line relays 4Pand 4J with the result that relay 4H releases and establishes the circuit of the red or stop lamp R of signal 48.

:- In addition, on release of the track relay 4TB its contacts short circuit the portion of the line circuit J connected to the linerelays 5P and 5N "to prevent "operation ofthese relays in the event energy'isimproperly' supplied" to the line,

circuit J.

-When the train advancesinto section 5T, track relay 5TB. releases and its contact I06 interrupts the circuit traced above for supplying energy of 120 code frequency to coding relay KCR and establishes another circuit for supplying energy of this frequency to relay KCR so that the supply of master code of 12 0"co-de frequency to line circuit K is maintained and feed-back energy continues to besupplied to the line circuit to maintain the display of .a clear indication by signal 63.

When the train advances into section 6T, track 'relay'STI'R releases and interrupts line circuit K.

and thereby causes signals 18 and 68 to provide their red 'or stop indications.

At this time contact I I5 of relaytTR establishes the pick-up circuit for relay 68R. "This circuit also includes front contact I16 of relay 5H, while on pickingup of relay BSR its contact I ll establishes a stick circuit which includes back contact H6 of relay 6H.

circuit J is .of 120 code frequency. This energy is ineffective to control signal 4S so that this signal continues to display its stop indication. This energy does produce operation of the impulse relay JIR so that feed-back energy is supplied to line circuit J. As'relay 3D is picked up, the feedback energy isof normal polarity andsignal 58 is conditioned to display its green or clear indication. Y

When the train advances far enough to vacate section 6T,track relay 6TB. picks up, but relay 6H remains released while relay BSR remains picked up by energy supplied over its stick circuit. On picking up of relay BTR its contact l0! interrupts the circuit traced above for supplying energy of 120 code frequency to coding relay JCR, and establishes a 'circuitincluding front contact H9 of relay BSR for supplyin energy of'180 code frequency to coding relay JCR so that master code of 180 code frequency is supplied to the line circuitJ. As relay 61-1 is released;t-his energy is of reverse polarity-s0 that signal 48 isconditionedto' provide itsyellow or caution indication.

- 7 'When the train advances into section 8T, track relay 8TB. releases and-interrupts the circuit of relay 8D, while contact [2! of relay 8TB completes the pick-up circuit of relay 88R. This circuit also includes back contact 122 of relay lTR,

while when relay BSR picks up its contact I23 establishes a stick circuit to keep the relay energized as long as relay 8TB. is released. I

In addition, onrelease of track relay 8TRthe signal BS is conditioned by means not shown to display its red or stop indication.

vOn release of relay B'I'R its contact I25 interrupts one circuit forv supplying feed-back energy to line circuit K,-but on picking up of relay 88R When the train advances into section 1T, track j lishes the circuit to permit feed-back energy to be supplied to line circuit J. However, master code is not supplied over the circuit'at this time so that impulse relay JIR remains released and.

feed-back energy is not supplied to line circuit J.

' .When the train vacates sections 4T and ET, the track relays 4TB. and 5TB pick up and complete. line circuit J to permit master" code to be supplied over this circuit. At this time energy of 120 code frequency is supplied to coding relay JCR over the circuit which includes back contact I0] its contact I26 establishes another circuit to permit this energy to be supplied. Accordingly, when the train vacates section IT and track relay 1TB. picks up to complete'line circuit K, master code is supplied over this line circuit so that impulses of energy are supplied to impulse relay KIR and thisrelay causes"feed-bac k energy to be supplied to the line circuit. As relay 5H-is picked up, the master codesupplied to line circuit K is of normal polarity'and conditions the signal is to display its green or clear indication, while as relay 8D is released, the feed ba'ck energy supplied to line circuit 1; is of reverse polarity so that signal 6S displays its yellow or caution indicatiOn. I

When the train vacates section II and feedback energy is supplied over line. circuit K so that relay 6H 'picksf up," its contacts change the master code energy supplied to the east end of line circuit J from reverse to normal'polarit'y.

Accordingly, "the contacts of relay 4? shift. from theinreverse'to their'normal positions and interrupt the circuit of the yellow lamp Y and establish the circuit of the'green lamp G of signal 4S. 1

Fromathe' foregoing it, will; be'seerrgthata the; modification shown: Fig 2; .like: that shown in Fig. 1, provides means employing a; singlelin'e circuit to control the signals for-bothzdizrections of traffic in antrack stretch, The modifications shown in Fig. 2; like; thatshowrr in:Fig-., 1,,em ploys master code: in the line circuit to control they signals for; one directionuof traffic; and' employsfeed-back codein the same line circuit 1 to control the signals forthe other direction of traffic. The; polarity. of the master and feedeb'ack, energy is controlled to thereby provide, two dis-- tinctive proceed indications for each direction of traffic.

In the system shown in Fig.- lwhen a train enters the overlap section at the leaving end: ot a passing Siding", the frequency offithe fmaste code is changed so that the intermediate /signal, governing trafiic in the opposite direction is placed at stop, but feed backif energy is supplied to maintain the display of anproceed indication by the headblock signal in front of the train.

In the system shown in Fig. 2 the master code is supplied at the end of the line circuit adjacent the intermediate signal location. When a train enters the overlap section, master code continues to be supplied over the line circuit to maintain the display of a proceed indication by the headblock signal in front of the train, but the supply of feed-back energ over the line circuit is cut off to thereby place the intermediate signal for the other direction of traiiic at stop.

In the system shown in Fig. 2 when th train advances into the track section in the rear of the intermediate signal, the frequency of the master code supplied to the line circuit in advance of the intermediate signal is changed. This causes the headblock signal at the leaving end of the passing siding in advance of the train to display a stop indication, but it also causes feed-back energy to be supplied to the line circuit to maintain the display of a proceed indication by the intermediate signal in front of the train.

Although we have herein shown and described only two forms of railway signaling system embodying our invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of our invention.

Having thus described our invention. What we claim is:

1. In combination, a stretch of railroad track having a pair of track rails over which tramc moves in both directions, the rails of the track stretch being divided by insulated joints into a plurality of track sections including an intermediate section having at one side a first section and at the other side a second section, a, first signal governing movement of trafilc from the first section into the intermediate section,- a second signal governing movement of traffic from the second section into the intermediate section, a line circuit substantially coextensive with and controlled by traffic conditions in said intermediate section, means governed by trafiic conditions in said first section for supplying to the line circuit master code energy of a first or second code frequency and of one or the other polarity, means responsive to master code energy of either frequency and either polarity supplied over said line circuit for supplying feed-back energy to said line circuit, means responsive to master code energy of one code frequency only supplied over said line circuit and selectively responsive to the polarity and mean responsive to feedebaclmenergy u plied-rover saidalinecircui't for. controlling saidr first signal 2. In, combinatiom; a stretch of railroad having a pair I of: track I rails=-- over wh ch 1 3 119;

moves inboth= directions -the rails of the-track,

stretch being dividedby insulated j oints ,--i-n -to a;

in said, first: section for supplying to the line cir-n, cuitmaster code energy; of a first-c or :a second code: frequency andof one or th other polaritw means responsive to master code energy of either frequency and either polarity supplied over saidline circuit for supplying feed-back energy to said line circuit, means governed by trafiie conditions in said second section for controlling the polarity of the feed-back energy supplied to said line circuit, means responsive to master code energy of one code frequency only supplied over said line circuit and selectively responsiveto the polarity of such energy for controlling said second signal, and means responsive to feed-back energy supplied over said line circuit and selectively responsive to the polarity of such energy for controlling said first signal.

3. In combination, a stretch of railroad track having a pair of track rails over which trafiic moves in both directions, the rails of the track stretch being divided by insulated joints into a plurality of track sections including an intermediate section having at one side a first section and having at the other side a second section, a first signal governing movement of trailic from the first section into the intermediate section, a second signal governing movement of traffic from the second section into the intermediate section, a line circuit substantially coextensive with and controlled by trafic conditions in said intermediate section, means for supplying to said conductors master code energy of a first code frequenc when said first section is vacant or is occupied by a train leavin said intermediate section and for supplying to said conductors master code energy of a second code frequency when said first section is occupied by a train advancing towards said intermediate section, means governed by occupancy of said first section and controlling the polarity of the master code energy supplied to said line circuit, means operated by master code energy of said first code frequency only and selectively responsive to the polarity of such energy for controlling said second signal, means responsive to the supply of master code energy of either frequency and either polarity for supplying feed-back energy to said line circuit, means governed by occupancy of said second section and controlling the polarity of the feed-back energy supplied to said line circuit, and means operated by feed-back energy supplied over said line circuit and selectively responsive to the polarity of such energy for controlling said first signal.

4. In combination, a stretch of railroad track having a pair of track rails over which trafiic moves in both directions, the rails of said track stretch being divided by insulated joints into a of suclr energy for controllingilsaid, second signals;

first, a' second, a third and a fourth section, a first signal governing entrance of trains into the second section from the first's'ection a second,

signal governing entrance of trains into the second section from the third section, a line circuit substantially coextensive with and controlled by trafiic conditions in said second section,-means for supplying to said conductors master code energy of a first code frequency when said first section is vacant or is occupied by a train leaving said second section and for supplying to said line circuit master code energy of a second code fre quency when said'first section is occupied by a train advancing towards said second section; means governed by occupancy of said first section and controlling the polarity of the master code energy supplied to said line circuit, means operated by master code energy of said first code frequency only and selectively responsive to the polarity of such energy for controlling said second signal, means responsive to the supply of master code energy of either frequency and either polarity over said line circuit and controlling a circuit over which feed-back energy may be supplied to said line circuit, means 'efiective only when said third and fourth sections are vacant or are occupied by a train leaving said second section to permit feedback energy to be supplied to said line circuit, means effective when said third section is vacant and said fourth section is vacant or is occupied by a train leaving said third section to cause the feed-back energy supplied to said lin circuit to be of normal polarity, means effective when said third section is occupied by a train leaving said second section to cause the feed-backener-gy supplied to said line circuit to be of reverse polarity, and means operated by feed-back energy supplied over said line circuit and selectively responsive to the polarity of such energy for controlling said first signal.

WILLIAM F. ZANE.

GEORGE W. BAUGHMAN.

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