US2298958A - Railway traffic controlling apparatus - Google Patents

Description

O t 3, 1942- R. A. M CANN RAILWAY TRAFFIC CONTROLLING APPARATUS Filed NOV: 5, 1941 .m W m m .A M w a H m B Patented Oct. 13, 1942 UNITED STATES PATENT RAILWAY TRA FIC GQNTRQLLING. APPARATUS 3 Claims.

Myinvention relates to railway trafiic controlling apparatus, and moreparticularly; to. the con trolof an, approachlocking stick relay ijor' electrically interlocking a track switch with therailway signals which. sorerntraflic movements over the;

In. the art of railway signaling, it is the pro-- vailing practice to guard against the inadvertent operation of a track switch when a trainis approaching; or passing over the switch by the pro vision ofa system; of relays. embodying suitable approach.v and. detector locking as illustrated, for example, in Letters. Patent Of the United States No. 1,959,072,. granted May 15, 1934, to Herbert A. Wallace, for Railway traffic controlling apparatus. or in LettersPa-tent of the United States, No. 2,141,074,, granted December 20, 1938-, to: Henry S- Young, for Railway trafiic controlling apparatus.

A feature of; such systems is the provision of an. approach; locking stick relay for eachsignalor group. of signals, which relay must be: energized order to. permit the operation of any switch included in a route governedby the signal. Usually the control of. the approach lock ins relay by the signals is effected through the medium of a back. lock or signal indication re-- lay, such as the relay L5 of Wallace, or relay ZRGP of Young, controlled over a circuit. including; contacts closed by the home signals in the; stop position, and it these signals include a mainline signal governing; high speed traffie move:--

men-ts, the back lock circuit also includes line.

wires extending along the trackway to the-corre-- sponding distant. signal andincludes contacts: closed only when the distant signal displays.- a restrictive indication;

Myinvention is an improvement upon thiscircuit arrangement, comprising the provision of entirely separate back lock circuits for the home:

anddistant signals.

One.- object of, my; invention is to: enable the;

approach, locking relay to be; held, energized as. long as; conditions; are proper, by means of local circuits which do notv extend beyond the limits. of the interlocking plant, and; which therefore;

are not dependent. upon'the conditionof the linecircuit: only, thereby preventing the approach locking relay from releasing to. render; the locking effective with respect to conflicting, routes, due to a. failure oi the line circuit leading to the distant signal occurring at a time when the home signals are at stop. and consequently no question. of. saf y or oper tio s nvol d- 1 shall. describe one form of apparatus embodying my invention, and shall then point out the novel featuresthereof in claims.

Referring to the accompanying drawing; the. track dia r t he. pni dis -m a s ret h f ytrack o w ch -mt n nisa p ed. the stretch. being: divided the: us lnranner' by insulated joints to form th track sections l 'I-.,. MIT and ZOE-leach; ofwhich-is provilie e with the usual; trackcircuit hav ng; atrack, battery; as. s and w essmd nsla n mbered t ac relay Section III constitutes a detector section includingthe; traclgswitchtSW, over which t-raflicmovements from left; to. right. are governed by the home: signals 23A and 23B, and from. right: to left by the; home signals and- Re y ZLGP is t a k 9 1 si nalin ication. rel yrep a g hes onr s tion e1 them s na A an Z B. an as how. ne ma v energized over. a circuit. extending from one-ter;-- minal Bof-a suitable local source of current ever contacts 3 and- 4, closed, when. signals and ZLB respectively indicate stop;, tl 1ro.1.1ghv the; wind-- ms of re y 1 GB eer: erm;i alor t samesource.

It will e d r oe a thes ie alsare u ject to the usual manual controrby the operation of a signal lever- 2V to left or right. to piclr up a signal control: relay. ZLHR. or. 2RH-R, as. shown... Signal: H] isan automatic blocls, signal comprising the distant,- signal. for signal 2%, and i con.- trolled inv the usual. manner over a line circnit. including from contacts of thetrack. relay HERE. and extending to, terminals 3- and-C. ofthe local; source of current over the pole: changer con tacts 5. controlled1 by signal Relay. IilRI-IGP- is the additional indication. rela provided: in ac cordance: withmyinvention and normally energizedover a circuit, extending from. one terminal Bill. of. a local. source of current atthe location of signal to, over. contact ,6 closed only when signal H], is at stopor caution, through the. winding of relay IBRHGB to the, other. terminal CID oithesame source.

Relay is the usualx approaeh. relay and is; normally energized over aline circuit. extending over front contacts; oi-the track; relays IDTR. and R- o: t er i a B20 nd C20 f; a l c source ofcurrentat the location; ojrelay R ay S AS s; the: ppro ch lockin relax associated with signals 2L A,. and tilt. and is normally held energizedotier an stickcircuitextending from: terminal B- over contacts. 1* and- B: of relays, Z-LHR. and Z-LGP, front contact. 9 and winding; of relay ZLAS. to terminal: G), as shown. r y he.- drawins I. have: shown in; detail only those. circuit relating: to traflie movements from right to left; but itwill. be understood. that generally similar circuits: ar re uiredior. the. op,

posite direction. That is, relay 2RAS is an approach locking relay like ZLAS and similarly controlled by the signals 2RA and ZRB. It is to be understood that the detector section IT is representative of a typical layout, and. that in practice, additional detector sections and track switches may be located between the opposing home signals shown. a

The track switch ISW is provided with the usual power operating mechanism comprising the switch machine ISM, which as indicated diagrammatically is controlled by a polarized switch control relay IWR. Relay IWR is manually controllable in accordance with the position of a switch lever IV, over a circuit including front contacts of the approach locking relays ZLAS and ZRAS and of the detector section track relay ITR.

Assuming the apparatus to be in its normal condition as shown, it will be readily apparent from the drawing that if lever 2V is moved to the left to pick up relay ZLHRJZhe opening of contact 1 will cause the approach locking relay ZLAS to release, thereby completing a circuit for clearing signal ZLA, analogous to the signal circuits of the Young patent above referred to, this circuit extending from terminal B at front contact [9 of relay ZRAS, over other contacts, not shown, as indicated by the legend Network, back contact ll of relay ZLAS, front contacts l2 and I3 of relays ITR and ZLHR through th operating mechanism for signal 2LA to terminal C. Signal 2LA therefore clears and by opening contact 4 and reversing the pole changer 5, releases relay ZLGP and also causes signal In to assume the clear position. Relay 2LGP upon releasing opens contact 8 in the circuits for relay ZLAS, while signal ID in the clear position opens contact 6 releasing relay HJRHGP to open contact I4 in the pick-up circuit for relay ZLAS. Contacts I5 and I6 of relay ZLAS being open, relay IWR is held deenergized to lock switch ISW in the normal position, as shown.

Assume now that the signal lever 2V is restored to normal, releasing relay ZLHR to restore signal 2LA manually to stop. The closing of contact 4 by the signal causes relay ZLGP to pick up, and the operation of contacts 5 causes signal I!) to again assume the caution position to pick up relay I URI-1GP. If sections HIT and 20T are unoccupied so that relay LAR is picked up to close its contact H, a pick-up circuit for relay ZLAS will be completed from terminal B over contacts 1, 8, l4 and I! through relay 2LAS to terminal C. Relay ZLAS may also be picked up in the usual manner after a time delay by the operation of a time element relay ITE, in the event relay LAR is not energized, or may be picked up automatically over back contact l8 of relay ITR if a train governed by signal 2LA enters the detector section IT, but since each of the pick-up circuits includes contact [4 of relay IORHGP, it will be clear that the return of signal 10 to stop or caution is fully checked, and that relay ZLAS cannot become energized unless signal HJ displays a restrictive indication, as in the systems of the'prior patents hereinbefore referred to. It will also be clear that after relay ZLAS is once picked up it is held energized over the stick circuit including contacts 1, 8 and 9 only, so that relay ZLAS is prevented from becoming released and consequently the switch ISW is free to be operated even though relay IURHGP is released, as might occur due to a failure of the back lock line circuit, as already explained. The reliability of the system is thereby increased, since the remaining circuits involved are to a large extent local.

Although I have herein shown and described only one form of apparatus embodying my 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 my invention.

Having thus described my invention, what I claim is:

1. In combination, a stretch of railway track including a track switch, a home signal for governing trafi'ic movements over said switch, an approach locking relay, circuits for controlling the operation of the switch including front contacts of said approach locking relay, a distant signal for governing the movement of traific approaching said home signal, a plurality of pick-up circuits for said approach locking relay each including a first contact closed only when said home signal indicates stop and a second contact closed only when said distant signal displays a restrictive indication, and a stick circuit for said approach locking relay including said first contact but not including said second contact.

2. In combination, a stretch of railway track including a detector section containing a track switch and an adjoining approach section, an approach locking relay, circuits for controlling the operation of the track switch including front contacts of said approach locking relay, a home signal for governing the movement of traflicfrom said approach section into said detector section, a distant signal for governing the movement of traflic approaching said home signal in said approach section, circuits controlled by said home signal arranged to cause said distant signal to display a restrictive indication when said home signal indicates stop, a first repeating relay arranged to be energized only when said home signal indicates stop, a second repeating relay arranged to be energized only when said distant signal displays a restrictive indication, pickup circuits for said approach locking relay each including front contacts of both said repeating relays, and a stick circuit for said approach looking relay including its own front contact and front contacts of only said first repeating relay.

3. In combination, a stretch of railway track including a track switch, two home signals for governing the movement of traffic in a given direction over said switch in its normal and reverse position, respectively, an app-roach locking relay, circuits for controlling the operation of said switch to normal and reverse effective only when said approach locking relay is energized, a distant signal in said stretch for governing the movement of trafiic approaching said switch in said given direction, a repeating relay associated with said approach locking relay, a line circuit extending to said distant signal for energizing said repeating relay including contacts closed only when said distant signal displays a restrictive indication, pickup circuits for said approach locking relay including contacts closed only when said home signals indicate stop and also including a front contact of said repeating relay, and

a stick circuit controlled by said home signals effective to maintain said approach locking relay energized regardless of the condition of said repeating relay.

RONALD A. McCANN.

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