US2365837A - Railway traffic controlling apparatus - Google Patents

Description

Dec. 26, 1944. J. M. PELIKAN 2,365,837

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed May 16, 1942 2 Sheets-Sheet l I A n l 9 2 v 1a 1/125 (an? F1 m. Mn/ I [IF J76 19 117 C7 v hig U L 1025 HE H @11 2 I Dec. 26, 1944. I J. M.- PELIKAN 2,365,837

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed MaylS, 1 942 2 SheetsSheet 2 H 4 7 --4b I I IE /1759 12 1P6? 111m? k Patented Dec. 26, 1944 RAILWAY TRAFFIC CONTROLLING APPARATUS I John M. Pelikan, Chicago, 111., assignor to The Union'Switchand Signal Company, Swissvale, Pa, a corporation of Pennsylvania Application May 16, 1942, Serial No. 443,240

My invention relates to railway traffic controlling apparatus, and it has particular reference to the organization of such apparatus into traffic controlling systems of the type in which code impulses of energy transmitted over either or both line and track circuits areutilized for effectin a control or controls.

. In general, it isproposed in accordance with my invention to provide novel and improved forms of railway traffic controlling systems of the type employing code impulses of energy. More specifically, it is pro-posed to provide railway trafilc controlling systems incorporating novel and improved means for generating the code impulses of energy transmitted over the control circuits.

In systems utilizing code impulses of energy, it is customary to employ code transmitters or coders which operate contacts and are efiective to cause the energy in a pair of conductors of a control circuit to be periodically interrupted or coded in such manner as to provide in such -circuit alternate on? and o periods during which current does and does not flow, respectively. It has been proposed to utilize coded current generated by a coder and supplied to a pair of conductors to generate in turn other coded current supplied to the said pair of conductors, thus causing a contro1 circuit to be supplied with two sets of code impulses, one set comprising a normal or master code generated by the coder and causing operation of a code following relay, and the second set comprising a reverse or feed back code generated by the action of the master code following relay and operative to cause operation of a feed back code following relay. It is an object of my invention to extend the selfgenerating feature of this arrangement by providing means for eliminating the necessity for a code transmitter, thereby providing a code system wherein each one of the two sets of code impulses applied to a pair of conductors is generated in response toythe other set of code impulses.

Another object of my invention is to provide a code system f signaling wherein the necessity for a code transmitter or coder is obviated by arranging the code responsive apparatus at the two ends of a circuit in such a manner that each code following relay generates and supplies to the circuit a code impulse in response to each impulse of codereceived by the relay from the circuit.

An additional object of my invention is the provision of novel and improved detector circuits l 14 Claims. (01. 246-38) employing code impulses of relatively short duration.

A further object is to provide novel and improved detector circuits employing code impulses of energy and arranged to be self-checking so that if any portion of the apparatus fails to operate properly, the coding action is terminated.

An additional object of my invention is to provide novel and improved detector circuits employing code impulses of energy and arranged to be immune to false current.

In practicing my invention, the above-mentioned and other important objects and characteristic features which will become readily. apparent from the following description, are at: tained by providing a pair of conductors with two energy sources and with two polarity responsive relays, and by energizing both of the relays simultaneously by energy derived alternately from first one and then the other of the two sources, the two sources being poled in opposition to each other so as to reversibly energize the relays.

I shall describe several forms of apparatus-embodying my invention, and shall then point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a diagrammatic view representing one form of apparatus embodying my invention applied to a control circuit of the track circuit type. Figs. 2, 3 and 4: are each diagrammatic views representing modified forms of'the apparatus illustrated in Fig. 1. In each of the several views, similar reference characters have been employed to designate corresponding parts.

Referring to Fig. 1, the referencecharacters l and la designate the track rails of a stretch of railway track divided -by insulated joints 2 into a plurality of successive adjoining track sections of which only one section, DE, is represented complete in the drawings. The rails l and la of section D-E comprise the transmission conductors of a control circuit of the track circuit type in which the conductors are ordinarily effective suitably distinguishing prefixes; Each of the relays TR is a polarity responsive relay of the polar stick type andhas an armature operable to one extreme position oranother according as the relay. is energized by current of one relative polarity or the other.

Relay WTR has associated therewith two slow releasing relays, designated by the reference character FSAE and HRI, respectively, and a polar stick relay M. Relay .l SAl is provided with a pick-up "circuit which extends from one terminal B of a suitable source of current, such as a battery not shown but having its opposite terminals designated in the drawings by the reference characters B and C, through polar 'contact closed in the reverse or right-hand position, as viewed in the drawings, of the polar armature of relay WTR, polar contact 6 closed in the :normal or left-hand position of relay M, and the winding of relay FSAI to terminal C. :Relay FSAI also i provided with an auxiliary circuit in which front contact I of relay HRI provides an alternate path around polar contact 5 of relay M. The other slow releasing relay HRl is provided with an energizing circuit which may be traced from terminal B 'throughpolar contact 5 of relay W'IR closed in itslnormal or left-hand position, front contact 1'0 of relay FSAL, and the Winding of relay HR to terminal C. Relay M is a twowinding relay provided with a normal energizing circuit which extends from terminal 18 through normal polar contact '9 of relay 'WTR-and one portion of the winding of relay M to "terminal C; with a reverse energizing circuit which extends from terminal B through reverse polar contactfi of relay W'IR, front contact H of relay FSAI and the other portion of the winding of relayM to terminal C; and with an auxiliary vcircuit which extends from terminal B through reverse polar "contact 9 of relay WTR, 'back contact 11 of relayFSAl, back contact 1'2 of relay HR! and the said one portion of the Winding of relay to terminal C.

Relay E'IR. (is provided with a slow releasing repeater or impulse generating relay ETPR-enertgized over an obvious circuit which includes terminal B, polar contact IE of relay ETR closed in its normal or left-hand position, the winding of relay ETPR and the other terminal C. Relay ETR maya'lso be provided, asshown, w ith aslow releasing relay FSA! energized over .pcilar contact I8 of relay ETR closed in its normal position,

and with another slow releasing relayHRz energized over an obvious circuit including reverse polar contact It of relay E'I'R and a 'front contact of relay FSAZ.

In the normal condition of the apparatus, section lD-E is unoccupied and relays E'IR and 'W'IR are energized. in series, by energy "derived alternately from the two sources "IB. Battery WTB. for example, energizes both relays WTR and ETR in series over a 'fi-rst track "circuit extending from one terminal of battery WTB through normal polar contact lls of relay M, rail 1 ffrcnt contact Fl of rela 'ET PR, the winding of relay :ETR, rail lu, and the winding "of relay to the other terminal of battery This track circuit is completed when relay M is in its normal position due to the errergiza'ti'on oi therelay over its normal circuit including normal polar contact -9 :ofrelay and when relay ETPR :is energized over its obvious circu t including contact 15 "of relay l-ETR. The "polarity of currentsupplied from battery WTB to the relays WTB :and ETR over the first itrack-circuittis such as to cause the relays to shift their respective armatures from the (illustrated {positions to the reverse or right-hand positions, whereupon relay ETPR becomes deenergized, and relay M is caused to shift its polar armature to its reverse position, thereby opening or interrupting the first track circuit by disconnecting battery WTB from the track rails and relays WTR and ETR. Relay ETPR releases, at the end of its release period, and opens its front contact .11 to open the first track circuit at that point. Back contact I! of relay ETPR now closes to connect battery E'IB to relays ETR and WTR in series over a second track circuit extending from one terminal of battery ETB through back contact I! of relay ETPR, rail 1, reverse polar contact H) of relay M, the winding of relay WTR, rail la, the winding'of relay ETR and to the other terminal of battery ETB. The polarity of current supplied from source ETB to the relays over the second track circuit is the reverse of that supplied from battery "WTB to the first track circuit and causes the relays to shift their respective armatures back to their normal positions, whereupon relay ETPR becomes energized and immediately picks up to open the second track circuit -by disconnecting battery ETB from the track rails and the track relays, while relay M becomes energized over its normal circuit and shifts its polar contact It to its normal position. The opening of reverse con- "tact it opens the second track circuit and the closing-of normal polar contact I6 completes the first track circuit by connecting battery WTB in circuit with'bot'h relays W'IR and E'IR. This cycle of operation continues as long as section D-E is vacant, hence relays WTR and are energized in series alternately first by current of one polarity derived from battery WTB and supplied over a first track circuit and then by current of theopposite polarity derived frombattery ETB and supplied over a second track cincuit. Each one of "these sources is connected in circuit --with the track rails and .relays for relatively short intervals of time in response to an impulse of -energy-received from the otherof such sources, with the result that each source of energy is caused to supply 'coded energy to the rails 'in The operation of track relays W'IR and ETR in response to the self-generated :code impulses :is detected by means of the associated slow acting relays FSA and HR. Relay FsAl, for example, becomes energized when reverse polar contact 5 and normal polar contact 26 of relays WTR and M, respectively, are closed, and picks up to "close its front contact I0 and prepare a circuit for relay FHR I, which circuit becomescompleted when normal contact 15 of relay W'IR closes. When relay HRil picks .up, another circuit for relay FSAzI is prepared, including reverse contact 5 of relay and front contact 'l of relay HRI, hence when relay W'IRoperates its polar arma- 'tur alternately to ffirst one and then the other position, relays .FSAJ and HR'I are alternately energized. These relays are provided with slow releasing periods, attained in part at least by means of resistors 18 connected across their terminals, selected to maintain the relays in their picked-up positions for intervals which bridge the intervals that their respective energizing circuits are open due to the operation of the polar contacts of relays WTR and M. Similarly, relays FSA2 and I-IRZ, associated with relay ETR, are both picked up when relay ETR is caused to reversibly operate its polar armature.

When a train enters the section, relay ETR either remains in or assumes its normal position, while relay WTR either assumes or remains in its reverse position. In other words, with a train in, the section, the two track relays are caused to operate their polar armatures to positions out of correspondence. For example, if a train enters the section when battery WTB is connected to the track rails, the train shunt established in the section prevents relay ETR at the opposite section end from responding to such energy, hence relay ETR remains in its normal position and relay ETPR is maintained energized. Relay FSAZ' also remains. energized, while relay'HR2 releases at the end of its slow release period to indicate that relay ETR is no longer "reversibly operating its polar armature. Relay WTR, on the other hand, becomes energized in series with the train shunt and operates its polar armature to its reverse position, thereby reversing the energization of relay M, which relay operates its polar armature in turn to disconnect battery WTB from the track rails. Relay WTR remains in its reverse position since no energy impulse of the opposite polarity is at this time impressed on the track rails, and relay HRI first releases to open its front contact I whereupon relay FSAI also releases. Relay M, however, now becomes energized by current of normal polarity over. its auxiliary circuit including reverse polar contact 9 of relay W'IR and back contacts I I and I2 of relays FSAI and HRI, respectively, where upon normal polar contacts 6 and I6 of relay M close. Relay WTR now becomes energized again in series with the train shunt, by current of the polarity corresponding to the reverse position of the relay, but no operation of relay WTB is effected by this current since the relay already isin its reverse position. Relay, FSAI, however, picks up over its pick-up circuit including reverse contact 5 and normal contact 6 of relays WTR and M, respectively, and back contact I I of relay FSAI opens to interrupt the previously traced auxiliary circuit. Front contact I I of relay FSAI is now closed to complete the reverse circuit of relay M, whereupon the polar contacts of that relay reverse to disconnect battery WTB from the track rails, and to deenergize relay FSAI When that relay drops, relay M again becomes energized by current of normal. polarity and shifts its polar contact members. 6 and I6. This operation of relays M and FSAI continues as long, as the train shunt is maintained in the section.

The relays M and FSAI cooperate in providing what I shall term code initiating means effective after the section becomes vacant to restor the apparatus of the section to its normal condition wherein the code impulses supplied to the two track circuits of the section are each caused to be generated by the action of the code impulses spective contacts to their normal positions.

lay M may be either in its normal or its reverse position. If contact I6 is in its reverse position, battery WTB is disconnected from the track rails and both relays WTR and ETR maintain their respective contacts in their last operated positions wherein the contacts are out of agreement. Then, after relay M is caused to operate its contacts to their normal positions in the manner pointed out hereinbefore (or if contact I6 is in its normal position when the train vacates section D-E), battery'W'I'B is connected with the track rails and it energizes relay ETR to cause that relay to operate its contact I5 to its reverse or right-hand position to deenergize relay ETPR. This latter relay in turn releases to open at front contact I! the previously mentioned first track circuit, and closes its back contact H to connect battery ETB to the track rails. At the oppositeend of the section, relay FSAI was picked up when relay .M operated to its normal position, so that relay M is energized over its reverse position and operates its contact I6 to its reverse position. The polar armatures of relays WTR, ETR and M now occupy correspondingrelative positions and the second track circuit is established whereupon both relays W'IR and ETR are energized by battery E'I'B and operate their re- Relays HRI and I-IRZ are now caused to pick up, and the apparatus of Fig. 1 is restored to its normal condition, as indicated in the drawings, wherein the two track relays are caused to be reversibly operated. It follows, therefore, that dueto the interaction of relays FSAI and M in causing the rails to be intermittently supplied with energy impulses when the section is occupied, -there is available in the section when it becomes vacant an initiating code impulse effective to restore the track circuit apparatus to its normal condition. After the track circuit apparatus is restored to normal, relay FSAI is held constantly energized and the interaction of relays FSAI and M ceases.

In an alternative form of the apparatus, represented in Fig. 2, relay WTR has associated therewith its track battery WTB, a slow releasing repeater relay AR energized over an obvious circuit including normal polar contact 5 of relay WTR, a resetting coder relay RCR energized over an obvious circuit including its own contact 2!] and back contact 2| of relay AR, and a slow pick-up track repeater relay WTPR energized over an obvious circuit including normal polar contact 9 of relay WTR. Relay ETR has associated therewith its battery ETB, and relay ETPR. is energized over its obvious circuit includin normal polar contact I 5 of relay ETR.

The apparatus of Fi 2 operates as follows: When the section is unoccupied, relays WTR and ETR are energized, in series, by current alternatelysupplied first from one battery over one track circuit and then. from the other battery over another track circuit. For example, I shall assume that the apparatus is in the condition represented in Fig. 2, that is, the normal polar contacts of track relay ETR and the reverse polar contacts of track relay WTR are closed, respectively, repeater relay ETPR. is energized, while relay AR is deenergized but is held up in its picked-up position due to its slow release characteristics. Under the assumed conditions, relays ETR and WTR are energized in series over a circuit-extending from one terminal otbattery "rails and ing of relay WTR, rail the winding of relay E'I'R and :Eront contact I?! of relay ETPR to the other terminal of battery The polarity of current supplied from battery ETB to relays I-ETR and WTR at this time is such that relay E'I'R is caused to swing its polar contacts to their reverse or right-hand positions, while relay WTR is caused to operate its'con-tacts to their normal or left-hand positions. :Relay ETPR accordingly becomes 'deenergized and drops to disconnect :battery E'I'B from the track relays, and relays WTPR and AR become enerized. Relay vAR is held up by energy in its normal picked-up position, and relay WTPRpicks 1 up at the end of its slow pick-up period to complete a circuit extending from one terminal of battery WTB through rail la, :back .contact of relay ETPR, the winding of relay ETR, rail 1, the winding of relay WTR, back contact 23 of relay .RCR and front contact '22 of relay WTPR to the other terminal of battery W'IB.

The polarity of current supplied at this time from battery to the track rails is such as to cause relays WTR and ETR to operate their polar contacts to their reverse and normal positions, respectively, whereupon relays .AR and WTPR become deenergized and relay WTPR immediately releases to disconnect battery WTB from the track rails, while relay ETPR becomes energized and picks up at the end of its slow pick-up period to connect battery 'ETB in circuit with the rails. This cycle of operation is re- 'peated as long as th section remains unoccupied.

When a train enters the section, relay ETR is caused to operate to its reverse or right-hand position in response to energy derived from its associated source ETB, while relay WTR is likewise caused to operate to its reverse or righthand position in response to energy derived from battery. WTB. Both relays WTPR and ETPR release to disconnect both batteries WTB and ETB from the track rails, but battery WTB is reconnected to the rails when relay releases to energize code-r 're'lay RCR. The coder relay, RCR functions as a code initiating means and intermittently closes its front contact 23 to connect intermittently battery WTB to the track rails so that when the train vacates the section and front contact '23 'of coder relay "RCR is closed, a code initiating pulse of energy is available in the section rails to operate relay ETR to its normal or left-hand position. When this happens, relay ETPR becomesenergized, and source ETB is connected to the "rails for energizing both relays WTR and ETR and for initiating the cycle :of operation previously mentioned in detail. This cyclic operation .of the track relay E'I R and 'WTR may be detected by means'of "relays HRand FSA associated with the track relays and arranged as shown provided for relay 'ETR (in Fig.1.

In Fig. 3, the apparatus illustrated in Fig. '2 is represented modified by incorporating the track relays WTR and E'I'R "in the respective first "and second track circuit, in multiple with the source *of such circuit. For example, in the normal condition of the apparatus, as represented in the drawings, battery ETB is connected over front contact 11 of relay ETPR to its associated relay ETR in multiple with the rails I and la and the other track relay'WTR. An impedance 2:5 interposed in the circuit of relay ETR prevents that relay from-establishing-a short circuit across the la, "whereas impedance 25 interposed in the circuit of relay W'IRis at this time shunted over an obvious circuit path including back contact 23 of .coder relay .RCR .and back contact :24 of relay WTPR. Relays ETR and W'I'R are both effectively energized and are caused to swing their respective polar armatures from the illustrated positions to their other posito connect battery WTB .to relay WTR..in multiple with the trackrails and relay ETR. The polarity of current supplied from battery WTB causes .both relays ETR and WTR to operate their respective armatures, whereupon relay WTPR releases and relay ETPR picks up. This cycle of operation is maintained as long as the section is unoccupied.

The apparatus of Fig. 3 operates in response to a train in the section in .a manner corresponding to that pointed out hereinbefore withreference .to the apparatus of Fig. 2, and further detailed description of the apparatus of Fig. 3 is believed to be unnecessary, except to point out that contrary to Fig. 2, like terminals of batteries ETB and WTB are connected to different rails of the section, hence when battery ETB is connected to the track circuit one rail is made positive with respect to the other, whereas when battery WTB is connected to the track circuit, the other rail is made positive with respect to the .one rail. The apparatus of Fig. 3 accordingly functions to generate two sets of code impulses, one having one polarity and the other having the opposite polarity.

The apparatus illustrated in Fig. 4 represents a still further modification of the apparatus of Fig. 1, wherein means are provided for attaining two-block, three-indication control of traflic by incorporating means for varying the intervals between successive impulsesof energy supplied from at least one of the sources, and by means utilized for detecting the differences in such intervals. Specifically, the apparatus of Fig. 4 corresponds to that of Fig. 1 except that the apparatus is represented applied to a stretch of track over which traflic normally moves in the direction indicated by the arrow in Fig. 4, or from left to right as viewed in the drawings; relay WTR has associated therewith an additional relay DR, energized over a circuit extending from terminal B through normal polar contact 3|] of relay WTR, front contact 3| of relay HRI and the Winding of relay DR to terminal C, for detecting short intervals between successive impulses of energy from battery ETB; a three-position signal S controlled by relays HRI and DR is provided adjacent to entrance end D of the section for governing traflic in the normal direction in the section; and a slow pick-up relay 2HP is provided at the exit end of the section. Relay 2HP is energized over an obvious circuit extending from terminal B through normal polar contact 32 of 'relay'ETR, back contact 33 of relay HR3 associated with the section next in advance of section DE, and the winding of relay 2HP to terminal C. Relay 2HP when energized provides relay ETPR with an obvious alternate energizing circuit which includes front contact 3! of relay 2HP.

The apparatus of Fig. 4 operates in a manner substantially corresponding to that pointed out in detail in connection with the apparatus of Fig. l, with the following modifications. When section DE and the section in advance are unoccupied, relay HRS of the advance section ispicked up to close its front contact 33, whereupon relay ETPR repeats the action of relay ETR and relatively short intervals intervene between successive connections of battery ETB to the track rails. Relay DR of section D-E at this time is provided with slow'pick-up characteristics and is adjusted to pick up only when contact of relay WTR closes a relatively large number of times per minute due to the relative short intervals between successive impulses from battery ETB. Relay HRI also is picked up, and lamp Gof signal S accordingly is caused to be energized over an obvious circuit including front contact of relay HRI, front contact 36 of relay DR and the filament of lamp G of signal S to terminal 0.,

When the section in advance of section DE is occupied, relay HRS associated with such section is released, relay ZI-IP is energized each time contact 15 of relay ETR is closed in its normal position; and at the end of its slow pick-up period, relay 2I-IP picks up to energize relay ETPR and thereby connect battery ETB to the track rails. The slow pick-up interval of relay 2H]? is now introduced into and added into the interval between successive impulses of energy from battery ETB, hence these intervals between impulses are relatively longer than the intervals between, impulses when relay HR3 of the advance section is picked up. The number of impulses transmitted in any given time is now less than when relay HR3 of the advance section is picked up, with the result that relay DR at the entrance end of section D--E is caused to be released, thereby conditioning the associated signal to display a caution aspect due to the energization of lamp Y over an obvious circuit extending from terminal B through front contact 35 of relay HRI, back contact 36 of relay DR and the filament of lamp Y of signal S to terminal C.

When section D--E is occupied and relay WTR is inactive, relays HR and DR associated therewith are released and signal S is caused to dise play a stop aspect in response to the energization over an obvious circuit of lamp R vof'signal S.

From the foregoing, it is readily apparent that I have provided novel and improved railway traffic controlling signal systems of the type employing coded energy and in' which the apparatus is arranged to eliminate the necessity for a code transmitter, thereby providing a code system wherein each one of two sets of code impulses supplied to a pair of conductors is generated; in response to the other set of code impulses; 1

Although I have herein shown and described only a few forms of railway trafiic controlling apparatus embodying my invention, it'is under-- stood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scopeof my invention.

Having thus described my invention, whatI claim is:' t y 1. In combination, a section of railway track, two polar track relays one at each end of said section, a first slow releasing relay energized when one of said trackrelays is in a given position, a second and a third slow releasing relay for the other of said track relays, a polarized relay for said other track relay, a normal energizing circuit for said polarized relay including a contact closed in a given position of said other track relay, a reverse energizing circuit for said polarized relay including a contact closed in the other position of said other track relay and a front contact of said second slow releasing relay, an alternate normal energizing circuit for said polarized relay including a contact closed in said other position of said other track relay and back contacts of each of said second and third slow releasing relays,'an energizing circuit for said second slow releasing relay including a contact. closed in said other position of said other track relay and a polar contact operated by said polarized relay and closed when that relay is energized in its normal direction, an alternate path in saidlast-mentioned circuit including a front contact of said third slow releasing relay connected around the polar contact of said polarized relay, an energizing circuit for said third slow releasing relay including a polar contact closed in said given position of said other track relay and a front contact of: said second slow releasing re1ay,a first source, of current for said one track relay and a second source of current for said other track relay; a; first track circuit for said section including i in seriessaid ,second source, the track rails, the

windings of. said twotrack relays, a front contact of said first slow releasing relay and a polar contactpf said polarized relay closed in the normal position thereof, said second source being poled tosupplycurrent effective to cause said track relays to operate from said given to said other positions; and a second track circuit for said section comprising in series said first source, the track rails, the windings of said two track relays, a back contact of said first slow releasing relay and a polarcontact of said polarized relay losed' when that relay is energized over a reverse circuit, said first source being poled to supply currenthavingamQlafity effective to cause said track relays ,to operate from said other to said givenpositions. V

2. In cornbinatioma section of railway track, two polar tra ck relays one at each end of said sectionand each having a first and a second posipeaterrelay is released for connecting said two track relays in circuit over thetrack rails to the one source associated with said one repeaterrelay, said one source being poled to supply current having a relative polarity effective to operate each of said track relays to its said second position, and circuit means rendered effective when said one repeater relay is released and said other repeater relay is "picked up for connecting said two track relays in circuit over the track rails to the'othersourceassociated with the other of said repeater relays, said other source being poled to supply current having a relative polarity effective to operate each of said track relays to its said first position,

c 3. In combination,-a section of railway track, two polar track relays one at each end of said section and each having a' given and another position, a slow pick-up repeater relay for each track relay, means for energizingone of said repeater relays when the" associated one track relay is in its said given position, means for energizing the other of said'repeater relays when the associated other track relay is-in its said other position; a source of current for each of said repeater relays, circuit means rendered effective when said one repeaterrelay picked up and said other repeater relay is released forconneotingsaid two track relay in circuit over the track rails to the one source associated with said one repeater relay, said one source being poled to supply current, having a relative polarity effective to operate each of said track relays to its said other position, circuit means rendered effective when said one repeater relay is released and said other repeater relay is picked up for connecting said two track relays in circuit over the track rails to the other source associated with the other of said repeater relays, said other source being poled to supply current having a relative polarity effective to operate each of said track relays back to its said given position, an additional slow release repeater relay for one of said track relays, a coding device energized over a back contact of said additional repeater relay, and means controlled by contacts of said coding device for intermittently impressing energy from the associated one of said ources to the track rails and said two track relays.

4. In combination, a section of railway track, two polar track relays one at each 'end of said section and each having a given and another position, two slow pick-up repeater relays one for each track relay, means for energizing one of said repeater relays when the associated one track relay is in its said given position, means for energizing the other of said repeater relays when the associated other track relay is in its said other position, two sources of current one for each of said repeater relays, circuit means rendered effectivewhen said one repeater relay is picked up and said other repeater relay is releasedfor connecting the one source associated with said one repeater relay to said one track relay in multiple with a circuit path comprising the track rails and said other track relay, said one source being poled to supply current having a relative polarity effective to cause each track relay to operate its armature to its said other position, and circuit means rendered effective when said one repeater relay is released and said other repeater relay is picked up for connecting the said other source to said other track relay in multiple with a circuit path comprising the track rails and said one track relay, said other source being poled to supply current havin a polarity effective to cause said track relays to operate back to said given positions.

5. Incombination, a section of railway track, two polar track relays one at each end of said section and each having a given and another position, two slow pick-up repeater relays one for each track relay, means for energizing one of said repeater relays when the associated one track relay is in its said given position, means for energizing the other of said repeater relays when the associated other track relay is in its said other position, two sources of current one for each of said repeater relays, circuitmeans rendered effective when said one repeater relay is picked up and said other repeater relay is released for connecting the one source associated with said one repeater relay to said one track relay in multiple with a circuit path comprising the track rails and said other track relay, said one source being poled to supply current having a relative polarity effective to cause each track relay to operate its armature to its said other position, circuit means rendered effective when said one repeater relay is released and said other repeater relay is picked up for connecting the said other source to said other track relay in multiple with a circuit path comprising thetrack railsand said one rack la sai other source e ng p led to s pp y u r nt havin a po arity efiective to cause said track relays to operate back to said given positions, a current limiting resistor connected in series with the winding of each of said track relays, and means effective when a repeater relay is released for establishing a shunt path around the resistor of its associated track relay.

6. In combination, a section of railway track, two polar track relays one at each end of said section and each having a given and another position, two slow pick-up repeater relays one for each track relay, means for energizing one of said repeater relays when the associated one track relay is in its said given position, means for energizing the other ofsaidrepeater relays -when the associated other track relay is in, its

said other position, two sources of current one for each of said repeater relays, circuit means rendered effective when said one repeater relay is picked up and said other repeater relay is released for connecting the one source associated with said one repeater relay to said one trackrelay in multiple with a circuit path comprising the track rails and said other track relay, said one source being poled to supply current having a relative polarity effective to cause each track relay to operate its armature to its said other position, circuit means rendered effective when said one repeater relay is released and said other repeater relay is picked up for connectingthe said other source to said other track relay in multiple with a circuit path comprising-the track rails and said one track relay, said other sourcebeing poled to supply current having a polarity effective to cause said track relays to operate back to said given positions, an additional slow releasing repeater relay forone of said track; relays, means for energizing said slow releasing repeater relay when said one track relay is in its said other position, a coding device energized over a back contact of said slow releasing repeater relay, and circuit means eifectivewhen both of said slow pick-up repeater relays are released and controlled by said coding device for intermittently impressing said one source to said one track relay in multiplewith said track rails and said'other track relay.

7. In combination, a section of railway track, two polar track relays oneat'each end of" said section and each having a-gi-ven and another position, two slow pick-up repeater relays one for each track relay, means for'energizing'one of said repeater relays when the associated'one track relayis in its saidgiven position, means for energizingthe other" of said repeater; relays when the associated other track'relayisiont inf its said other position, two sources ofcnrreni' one for each of-said repeater relays,'circuitmeans rendered effective when said one repeater relay is picked up and said other repeater relay is released for connecting the one source associated with said one repeater relay to-said one track relay in multiple with aci-rcuit path comprising-- the track railsand said other track-relay, said one source being poled to supply current havin arelative'polarityeffective to cause each track relay to operate itsarmature toits said otherposition, circuit means rendered elf active when said one repeater relay is released and said other repeater relay is picked up for; connectlng the said othersoureeto saidother track relay inmultiple with a circuit path'co'mprising the track rails and said one $15M); relay, --said other source being poled to supply current having a polarity effective to cause said track relays to operate back to said given positions, an additional slow releasing repeater relay for one of said track relays, means for energizing said slow releasing repeater relay when said one track relay is in its said other position, a coding device energized over a back contact of said slow releasing repeater relay, circuit means effective' when both of said slow pick-up repeater relays are released and controlled by said coding device for intermittently impressing said one source to said one track relay in multiple with said track rails and said other track relay, two current limiting resistors one connected in series with the wind ing of each of said track relays, a circuit completed through a back contact of said other slow pick-up repeater for shunting the resistor of the associated other track relay, and a circuit completed through a back contact of said coder and a back contact of said one slow pickup relay for shunting the resistor of the associated one track relay.

8. In combination, a section of railway track, two tracl; relays one for each end of said section, two sources of current one for each section end, a first track circuit for said section comprising the source at a given section end and the track rails and the windings of both of said track relays, means controlled by the track relay at the opposite section end effective each time when energized over said first track circuit to open such circuit and complete a second track circuit comprising the other source .at said opposite section end and said track rails and said windings of said track relays,means controlled by the track relay at said given section end efiective each time when energized over said second track circuit to open such circuit and complete said first track circuit, and mean governed by the track relay at said given section end for controlling traffic entering said section at such section end.

9. In combination, a stretch of railway track including a track section .-two track relays one for each end of said section, two current sources one for each section end, a first track circuit for said section comprising the source at a given section end andthe section rails and the windings of both of said track'relays, means governed by the track relay at the opposite end of the section eifective each time when energized over said first track circuit to open such circuit and complet a sec- 1 nd track circuitcomprising the other source at said opposite section end and the section rails and the windings of both track relays, means controlled by the track relay' at said given section end effective each time when energized over either said first or said second track circuit to open the respective circuit, additional means at said opposite section end governed by trafiic conditions on said stretch beyond that section end for completing said first track circuit at the end of one or another predetermined time interval dependent upon traffic conditions on said stretch, and means both of said track relays, means governed by the track relay at the opposite end of the section effective each time when energized over said first track circuit to open such circuit and complete a second track circuit comprising the other source at said opposite section end and the section rails and the windings of both track relays, means controlled by the track relay at said given section end effective each time when energized over either said first or said second track circuit to open the respective circuit, additional means at said opposite section end governed by traffic conditions on said stretch beyond that section end for completing said first track circuit at the end of one or another predetermined time interval dependent upon traffic conditions on said stretch, means controlled by said given section end track relay for governing trafiic in said section and responsive selectively to the different intervals existing between successive completions of said first track circuit, control means controlled by said given section end track relay for detecting the successive energization of such track relay alternately over said first and second track circuits, and for distinguishing between the difi'erent intervals existing between successive completions of said first track circuit, and means at the said given section end controlled by said control means for governing traffic entering said section at said given section end. I

11. In combination, a section of railway track, two polarity responsive track relays one for either end of said section and each having agiven position and another position, two controlled relays one for each track relay and each having a first position and a second position, means controlled by each track relay for operating the associated controlled relay to its said first position or said second position according as the track relay is in its said given position or said other position, two sources of current one for each section end, a first track circuit for said section including the source at a given section end and the track rails and the windings of both of said track relays and first positioncontacts of each of said controlled relays, said given section end source being poled to cause operation of each of said polarity responsive track relays from its said given position to said other position, a second track circuit for said section including the source at the opposite section end and the track rails and the windings of both of said track relays and second position contacts of each of said controlled relays, said opposite section end source being poled to cause each of said polarity responsive track relays to operate from its said other position to its said given position, and means controlled by one of said track relays when reversible operation thereof is terminated by the shunting action of a train in the section for applying to the track rails code impulses of energy from the source at the associated end of the section.

12. In combination, a section of railway track, two polarity responsive track relays one for either end of said section and each having a given position and another position, two controlled relays one for each track relay and each having a first position and a second position, means controlled by each track relayfor operating the associated controlled relay to its said first position or said second position according as the track relay is in its said given position or said other position, two sources of current one for each section end, a first track circuit for said section including the source at a given section end and the track rails and the; windings of. both at saidtrack relays and first position contacts, of each, of said con-- trolled relays, said given section end source being poled to cause operation of each of saidpolarity responsive track relays from its said given positi'onto said other position,-a. second track circuit for said section including the source; at the opposite section end and the track rails and the windings: of both of said track relays and second position contacts of each of said controlled relays, said opposite secti'o'n end source being poled to cause each of said polarity responsive track relays to operate from its said. other position to its said given position, and; means controlled by oneof said track relays effective when said section isv occupied by a. train. for operating, the associated controlled relay alternately to its said first and second positions,. whereby intermittently to impress the source at'th'e associated section end. across the track rails of said section.

1:3. In combination, a section of railway track, two polarity responsive track relays one for either end of said section and each having a given position and another position, two controlled relays one for each track relay and each having a first position and a second position, means controlled by each track relay for operating the associated controlled relay to its said first position or said second position according asthe track relay is in its said given position or said other position, two sources of current one for each section end, a first track circuit for said section including the source at a given section end and the track rails and the windings of both of said track relays and first position contacts of each of said controlled relays, said given section end source being poled to cause operation of each of said polarity responsive track relays from its said given position to said other position, a second track circuit for said section including the source at the opposite section end and the track rails and the windings of both of said track relays and second position contacts of each of said controlled relays, said opposite section end source being poled to cause each of said polarity responsive track relays to operate from its said other position to its said given position, and means controlled by the track relay at one endof said section, effective when energy from the source at the other section end is shunted away from such track relay by a train in' said section, for operating the controlled relay 2-, con act associated with such track relay alternately to its said: first and said second positions whereby to impress intermittentlyonv the. track rails the source at said one section end.

14:. Incombination, a section of. railway track, two polarity responsive track relays one for either end of said section and each having a given position and another position, two. controlled relays one for each, track relay and each having. a first position and a second position,, means controlled by each track relay for operating the associatedcontrolled relay to its sa-i-dfirst position or said second .position according as the track relay is in its said given position or said other position, control means associated with one of said track relays and controlled by trafilc conditions beyond the. end of the section at which said one track re.- lay is located for at times delaying, the; operation of the associated controlled: relay from, one 0t its positions. to the other following: the operation of said one track relay from one position t the other, two. sources of current. one, for each. section end, a first track circuit for said section including the source at a given: section end and the track rails and the windings of both of said track. relays and first position. contacts of each of said controlled relays, said givenv section end source being poled tov cause: operation of each of said polarity responsive track relays from its said given position to said other position, asecond track circuit for said section including the source at the. opposite section end and the track rails and the windings of both of said track relays and second position contacts. of each of said controlled: relays, said opposite section end source being poled to cause each of said polarity responsive track relays to operate from its said other position to its said given position, means associated with the other of said track relays responsiveto reversible operation of that track relay and other means associated with that track relay selectively responsive to reversible operation of that track relay when operation of said one track relays associated controlled relay is delayed by said control means, and means controlled by one of said: track relays when reversible operation thereof is terminated by the shunting action of a train in the section for applying to the track rails code impulses or energy from the source at the associated end of the section.

JOHN M. PELIKAN.

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