US2662972A

US2662972A - Apparatus for the control of electric switch locks in centralized traffic control systems for railroads

Info

Publication number: US2662972A
Application number: US102074A
Authority: US
Inventors: George L Trout
Original assignee: Westinghouse Air Brake Co
Current assignee: Westinghouse Air Brake Co
Priority date: 1949-06-29
Filing date: 1949-06-29
Publication date: 1953-12-15
Anticipated expiration: 1970-12-15

Description

Dec. 15, 1953 G. L. TROUT 2,652,972

APPARATUS FOR THE CONTROL OF ELECTRIC SWITCH LOCKS IN CENTRALIZED TRAFFIC CQNTROL SYSTEMS FOR RAILROADS Filed June 29, 1949 2 Sheets-Sheet l E55 a a Q N N N N N N ZLA 25b L --I ZLAPa EL Energized when:

IN VEN TOR.

Gear 6' Troa.

HIS 147 2 0811 1 I IZRA G. L. TROUT 2,662,972 APPARATUS FOR THE CONTROL OF ELECTRIC SWITCH LOCKS IN Dec. 15, 1953 CENTRALIZED TRAFFIC CONTROL SYSTEMS FOR RAILROADS 2 Sheets-Sheet 2 Filed June 29,

E RQ 1r JNVENTOR.

( L Traced.

HIS HTFOHNE Y Patented Dec, 15, 1953 iliGE .KBPKRAT'US FOR "THE (10mm me iTRlC SWITCH LOCKS *CGN'I'BOL Gauge L. .Trout, 'ilfainesville, 7411110 1 M 'Wesflnz'lmuse .iBuke mumm 2 am .mumrmuszzs, 1949, Serisl No. 102374 track with passing "at :the minds 1:; the

blocks sate-m1 the summation-1111mm moveznents sever the switches mnd thzongh @the .ibkocks which extend to similnfly summed flosstions. The switenes wind ssignais rmae interlocked :by m ans :of nppmach inching 81835, and :a :.code 2WD?! nemnte cornmeal system nztovlded maxing the mwitches and :signals are nontrollahis 40y ic d'e s gnals atrammitted mom 11 min mi- 9 Claims. 346-5161.)

:rectoris rzffice. .nn xssentim {safety zrenuimmnt fior such systems :is what- :an :electric lock "with riapntomh m time lacking epmtectinn must be provided :iur each zoutlying hands-threw :swnch which :connects the :main track with an ,indmtry tztack. zblind siding 601 @the :like, :at am intermediateflointinniblnck. 1

My inventinn is manticulariy mdanted {or @the control of electric incks dor znroteoting ithe switches 19f such mind sidingsjmcentralized Maffit: acontrol :tenritary.

A :hlind siding, aas @de'fined in the ,book, The Signal Dicbienary, :1-9'1-1 teditiq'n, :is :one .havin no station or open telegraph Lattice. .As applied to "a centralized trams :contml :system, "this term designates massing txacks equipped with fhand throw switches at ;both ends and located within as single track black whieh extends rhetween :two v:m'jacent stations OI the system.

-I-n confnrmity with the inequired :practice for outlying hand throwxtmck switches in senma-l ized tramp control territory, the :track switches 10! the blind siding to which my invention as applied are provided with -,e1e,c'tri c looks with. time lookin ptotection, and control direuits are provided by which these may :be released to permit ztrain movements into or out :of the side :track only :under ;pr9per traflic conditipns :and with the authorization of the :tram director, by the operationof a :eede .o:ontrc 11edswitch lock controlrelay a theistation at Qneend-cf the block containing the blind siding: he cimuits my ihwention include ;t -he conventional provisions shy whichsan -;unluck may be obtained afor a train to enter :the' side track, when euthanized, if :thextmin Bis mmade nf thetmitch, nrzto sleeve ito water :main drank. amended the monk is 4111-- nbcupied and :the which :govern #thmngh strain movement: :into the are rat atop and timeusuabapnmmhilmungemmrasseciatedwith the signals are en r iz d.

The :ohject Km the rpresent invention is to provide additional ziacihties iby means '0! which tthe mm controllers mxthotimtion to enter the-siding :at zeitherizend mitiam the unemtion 4)! :time looking npparams ifm unlocking :the sw1tch at .nthnr :0! we raiding aim is suitable {time :intezval. u'rhis 01 :my :111- V ventien gpmvides knot heretofore avail- ;able. io'r example, 3's :eiitbled to enter widmgtat Ame ;end.' when authorized. l wing on :sthe mam do then track eswitch at the assume ortnesidmg vmnrrthwrintuit-mt n! invention iis so more iinlly merlnck "the mutbing attack switches with :the block signals Ethan IhemM0m.,ahy -;the zprmzismn of means whereby the :anthnnizaztim 5101' unlockmg rthe nutlying @track switch is governed iin-de- 31701169116 40! the aconditio'n of d cunancy m! the block by -the rcpndition :0! the :anpmadh flocking I mel -vs associated with %the. b1ack zslgna'ls :at both ends of the block. In 'accordancrwith ihis'teasture'of my rinventionza. imintanovementdm the side :tnack to flahe'main tmck-"cannnt yhestauthurized when @a signal has fbmn cleared ifor :a through strain movement zthmugh T the black mgr immedintely inflow-ins the manual metnm 0! Ethe signal $0 its :QbQD imflltiun. that only after as. smitable dieflay fperiod apparatus associated with My invention is indt limited in :its application so the particular case mribed :by way illustmtian, but is equally advantageous in anther situations, such as for the eprotection of a single "nutkying switch. .dor example.

One 'form m apparatus embodying my -inven- Mon \Will mow be idescribedmnd the :novel lea.-

memo: my invention. 7

In ithe drawings, :simflnr meferenoe *dhairacters meter to similar an bdthviews; "and to simwwms hnn arm in m thelocal sources of energy for the circuits are shown, these being designated B and N, respectively.

As shown in the drawings, the main track, illustrated schematically as a single line, is divided into track sections of suitable'lengths by the usual insulated joints; Each track section'is provided with a conventional track circuit identified by the reference character T with distinguishing numerical prefix. Each track circuit is provided with a track battery TB connected across the rails at one end, for supplying energy to a track relay TR over the rails of its section.

The apparatus of my invention is suitable for use with signaling systems of various types, and by way of example is shown applied to a system of the controlled manual block type having no intermediate signals.

The operation of the track switches IW and 'IW at the ends of the block does not need tobe considered in connection with my invention. It will be assumed that these switches remain in their normal position and that trailic movements through the block are governed by signals ZRA and 8LA, signals ZRB and BLB remaining at stop. Signal ZRA is governed in a conventional manner in accordance with traffic conditions in the block by a polarized line relay 2RHD and a slow acting repeater relay 2RHP.

Relay 2RHD is controlled over a line circuit which includes the

line wires

23 and 24 and ex tends the length of the stretch, and as will be clear from the drawing without tracing the circuit in detail, extends from terminal B at a front contact b of an approach locking relay '8LAS over front contacts of each of the track relays TR and front contact b of a switch lock relay WLR to terminal N at the contacts of a pole-changer relay BRAPC associated with signal 8RA. Signal 2RA is of the color light type having lamps G, Y and R, the circuits of which are controlled by relay ZRHD and by a signal relay 2RAH. The latter relay is controlled in a conventional manher over a front contact of relay 2RHP, a back contact of the approach locking relay 2RAS, and a front contact of a signal control relay 2RHS, its circuit including a contact n which is closed only when the track switch [W is in its normal position as shown.

Normally the red lamp R of signal 2RA is lighted to cause signal ZRA to indicate stop, but when relays ZRHS and 2RHP are both energized, relay ZRAS releases to complete the circuit for relay 2RAH, which relay then becomes energized to cause signal ZRA to indicate caution or proceed by the lighting of lamp Y or G in place of lamp R. The caution indication of signal IRA is displayed when relay ZRHD is energized in the reverse direction, as shown, and the proceed indication is displayed only when signal 8RA is cleared, in which case relay BRAPC picks up to cause relay ZRHD to assume its normal position in which its left-hand polar contacts are closed.

Relay ZRAS is picked up in the usual manner when relay ZRHS is released, either over a back contact of the track relay ITR when signal 2RA is put to stop by a train in section IT, or after the usual time looking period imposed by a time element relay ZTER, when the signal is put manually to stop.

Signal 8LA, for the opposite direction, is governed over circuits by a signal relay BLAH, its circuit being similar in all respects to those for signal 2RA. The line circuit for signal 8LA includes the line wires 2| and 22, and this signal -is arranged to be cleared only when the track switch 1W is normal. The relays involved include the track relays, the switch lock relay WLR, the pole-changer relay ZLAPC for signal 2LA, the approach locking relay 2RAS, the polarized line relay BLHD and its repeater BLHP, the approach locking relay 8LAS, the time element relay BTER and the signal control relay BLHS.

The remote control system may be of the type shown in Letters Patent of the United States No.

2,229,249, issued January 21, 1941, to Lloyd V. Lewis for Remote Control Systems, to which patent reference may be made for a detailed explanation of those features of the centralized traflic control system not shown herein. For an understanding of my invention, it is sufficient to note that the system providesa plurality of intermittently available control channelsbetween the oflice and the stations for the control of the block signals and of the adjacent tracl' fzlns and also provides indication channels for indicating traffic conditions and the condition of the controlled devices at the, pflice, Consideration. I of the manner in which this is accomplish'edis not needed, and to simplify the accompanying drawings, the channels employed for signal and switch lock control purposes have been replaced by the equivalent direct wire circuits. That is to say, as shown, the signal control relay ZRHSis controlled over the line wire 20 in accordance with the position of the corresponding signal lever ZSG at theofllce, and the signal control relay BLHS and the switch lock'control relay WLS are similarly'controlled by the signal lever 8SG and switch lock lever WL at the office.

It is to be understood that the hand throw switches 3W and SW at the ends of the blind siding are each provided'with a suitablehand'throw switch stand, such, for example, as' is shown in Letters Patent of the United States'No. 2,184,870, issued to H. L. Bone and K. G. J .McGowan'on December 26, 1939, for RailwaySwitch Operating Mechanisms and that the switch operation is governed by a suitable electric 'lo'ck having a lock magnet 3WL or 5WL, the circuits for which are arranged in accordance with my invention. The electric switch locks are preferably of the type shown in Letters Patent of the United States No. 1,126,834, issued February 2', 1915, to W. P. Neubert and W. E. Smith for Electric Switch Locks.

Considering for example the lock for switch 3W, in Fig. 1A, it will suflice to point out that the operating lever 8 of the switch stand is normally locked mechanically in a position to maintain the track switch locked normal by a lever latch a tached to a segment 25 which is held in looking position by the bail 50 of a padlock. To unlock the switch the padlock must first be removed by the train crew to permit the segment 25 to be moved a short distance to a position to engage the locking dog 21 and to close contact 46 and to also open contacts such as 41 and 49 in the circuit for a normally energized indication relay, such as relay SNWP. Then if trafllc conditions as reflected by the circuits are such as to indicate that it is proper to unlock the switch, for example, if the train director has authorized a train which is occupying the short releasing section 03T to enter the siding by energizing the switch control relay WLS, the lock magnet 3WL will become energized to open contact 48 in the circuit for 'relay SNWP and to lift the locking dog 21, permitting segment 25 to be moved to its full reverse position in which the switch operating lever 8 is free to be operated. The switch stand is equipped with the usual switch circuit controller and point amine detector having normal. and. reverse: contacts n andr in:thezcircuitiorrelay; SNWR.

In accordance with my invention the switch ins dication re1ay-5NWP is -made=a:po1arizedrelay,and its circuit has adual function. The -circuit for relay SNWPeXtends-l from tenmina1s;l3 andN at poleechanger contacts-of the approachlockingmelay- ZRAS; at the leftehandi end of the block: over line wires to the location of switch: 332% thence over. thecontacts-M, 48iando4ll, the normal contacts not the circuit controllerfor; switch 3W, line wires 26.- and 28 and the normal contacts, n of the circuitvcontroller for switch 5W, contacts 41a, 48a anddlla a back. contact bot a time, 16.-

mentrelay S EERand thence th zoughpthe wind:

ing of relay ENWP.

The circuit for relay ENWP is arrangedin the usual manner so that. therelay. isshort circuited by the contacts 11 when the switchis open or reverse d-,.or by the switch lever oontactswhenv-these are ineither the intermediate or the, reverse position.

It willv be understood that the closing. of. he neutral contacts; a and ll of. relay BNWR indicates that both switches 3W and SW are properly locked in the normal position, for through train movements, and that thcpolari contaeto is closed to, enable relay STER. to be operated, only when relay ZRAS isenergized;

The-timeelementrelay SJI'ERhaS atimingcontact a which closes only when energy is supplied to the. relay 01: a time, period which may bead- Justed to. have adurationof two minutes or more and a checking contact. 22 which is closed only when the. relay is deenergized-l and, ntact. a s. in the. position it normally occupies at the be innin of? the measuredtime period; A suitable relay is shown for example in Letters Patent of the United States No. 1,966,965, issued July 17," 193 2, tol3; Lazich et al;

The circuit for the switch lock relay WLR by means of which the unlocking of the switches is authorized extends over contacts a and bof relay ENWP at the location ofswitch 5W to the right-hand end Off the block where the circuit-is supplied with energy from terminals Band N over pole-changer contacts of the switch control relay WLS' through the Winding of an indicating relayWLP, and this circuit also serves two purposes, in that relays WLR and WLPare repeaters of relay SNWP, with respect to the operation of their neutral contacts, while the polar contacts of relay WLR reflect the condition of the switch control relay WLS. The release of relay 5 NW'P releases relay WLP and thereby energizes an indication relay WK at the office, lighting a lamp WE to indicate the. unlocked condition of the track switches.

In addition to the foregoing the apparatus of my invention includes a stick relay 5A5 at the location oi switch 5W which is governed by relays WLR and STER and by twov auxiliary line relays EAR and WAR. The purpose ofrelay 5A8 is to enable switch 5A to be unlocked even though the release section 951? is not occupied, and to control the, polarity of the current supplied over line.

wires

29 and 30 to a polarized repeater relay BASP at the location of switch 3W'to enable that switch to be unlocked when section 63'1" is not. occupied. Relay SASP is supplied with energy over contact 1 of relay WLR and therefore is energized only when an, unlock is authorized.

Consideration of through train movements under the control of signals Z'RA and QLA is not needed for an understanding of my invention, ex-

:6. ceuttono etbatsmcerelayzWhite-m crocosms); relay 5W8, tsfront ontac s; ca db ma hs 15cnalline ircuitanreventthe clearing i e thersigna-lexcept when thelswitches 3 W and; SW are. properly locked in; their normal positions.

Assuming first that a train approaching switch 3W irom the left qccupiesthareleasesection. 03-1, andthat theitrain; crew-by means oi atelephone at the switch locationhas-requested authority to. enter the side track, thefltraffic director will reverse the, switch lock lever WL, energizing the switchcontrol relay W145. and thereby reverse the polarity of, the current supplied to relay WLR, which relay assumes its reverse position, closing its right-hand polar contacts d, e and. fl, and in response totheclosing of contact I of relay, WLR, relay SASP becomes energized by current of reverse polarity, closing its, neutral contact aand right-hand polar: contact 0..

Switch 3W may now be unlocked in the usual manner by moving the lock lever to, complete, the

circuit, for magnet 3Wh which includes the, neu: tral contact V and. rieht han la on ct relay 5ASP, and baclg contact e of the track relay 0313.

Alternatively, switch 5W may now be unlocked in the event the train is. approaching from the right and is occupying the release section. 05T. by moving, the switch lock lever to. complete the circuit for magnet, SWL, which. includes, contacts e'ofrelays WLR and 0,.5TR.

A feature of my inyention is that thereversal of relay WLR, as above described. also completes a circuit, for the time element relay SFIER over the right-hand polar contact 2. of relay WLR, back contact aoi relay 5A8, and the normal conta t. c of re ay SNWB- Re BEER th upo becomes energized and immediately opens its contact: b. tovrelease relay ENWP, and after atime in erval oi tw minu es. or m re, clo e ts. ontact a to energize relay 5A3, which. releases relay 5TEB, g

The opening of the lever contacts 41 and 4,9- or 41a. and. 49a by the train crew also opens the,c ir-.

-; cuitior relay 5NWP, which. relay upon releasing,

releases relays WLB and When relay WLR is deenerg-ized, its rightehand polar contacts (1 e nd I remain close but rel y WLP opens it neutralcontacts. a, b. and c. in the signal line circuits which. insures thatv signals ZRA and HLA areheld at stop and presents the energization of relays WAR and and relay WLP energizes relay WKto light the indicatiQn lamp, WE at the Off ce. l

Since relay WLB isireleased by unlo in e switch or by the, operation of relay STE E, it fol lows that an unlock when, accepted cannot be cancelled by the train director until the switch has. been r stored to normal and lock d y t train crew nor can it. be cancelled while relay ETER is in. opera ion- Y The. operation ofthis feature of. my invention may be illustrated by assuming that the, train which entered the ide. track via swit h. 5W after having. restored, and locked switch 5W normal arrives at swi ch 3W- When relay 5A8 p s up at the end of the time period of operation of relay itsv contacts. 0, and d. change the polarity of the current supplied to relay SASPfrom reerse. to no mal and re y 5A8? closes it lefthand Contact c to pre are. a circuit for. magn t 3W which does not. inclu e on act c. of relay 03TH, enabling switch 3W to be, unlocked to enable the t ain to re-ent r he main trac At the same time, a circuit for magnet SWL is 7 prepared over contact e of relay WLR and contact b of relay GAS, which does not include contact e of relay 05'I'R and consequently enables switch 5W to be unlocked if the train entered the side track via switch 3W and is to leave via switch 5W.

It will be seen from the foregoing that the effect of the operation of the switch lever WL is to prepare two circuits for unlocking each track switch to which my invention is applied, one to enable a train to leave the main track and another to enable a train to enter the main track with time locking protection, even though the block is occupied.

It follows that the system of my invention enables a train to obtain authorization to enter the side track over either switch, leaving cars on the main track, and to then return to the main track over either switch to pick up these cars. The necessity for the time delay imposed by relay STER will be seen from the fact that if cars are standing on the main track when the operator authorizes an unlock, the track circuit conditions are the same as when the block is occupied by a through train. In the latter case, relay BTER provides the required time looking protection to prevent the unlocking of the switch in front of an approaching high speed train.

In the foregoing example the authorization to enter the block was granted before the train left the main track, in which case the block signals are held at stop by the train, but it may also be granted when the train is on the side track and the switches are closed and locked normal, even though the block is occupied, but under conditions affording time locking protection and then only if the block signals 2RA and 8LA are properly at stop.

A feature of my invention is the provision of a contact d of the approach locking relay 8LAS in the circuit for the switch lock control relay WLS. This prevents the operator from reversing relay WLR when signal BLA is at clear, at which time relay 5NWP is energized to complete the circuit for relay WLR, and also for the time looking period by which the energization of relay BLAS is delayed by the operation of relay 8TER, following the manual return of signal 8LA to stop. Another feature of my invention checks the condition of relay 2RAS and thereby provides corresponding protection with respect to signal 2RA, due to the fact that the circuit for relay SNWP has been extended to the left-hand end of the block and pole-changer contacts of relay 2RAS included therein, as already explained, for controlling the position of contact of relay SNWP, in the circuit for relay STER.

It will be seen that even though relay WLR is reversed, relay STER will not operate if signal ZRA is at clear, nor during the period by which the energization of relay IRA-S is delayed by the operation of relay I'IER, following the manual return of signal ZRA to stop.

In addition, the energization of relays A8 and 5ASP as is necessary to enable the switches to be unlocked to enter the block, is delayed by the time of operation of relay 5'I'ER, providing time looking protection in the event the block is occupied by a through train.

Assuming next that a train standing on the side track has requested authorization to enter the main track at a time when the block is un occupied, signals ZRA and 8LA are at stop and the approach locking relays 2RAS and BLAS are both energized, as shown in the drawings.

Under these conditions the reversal of relay WLR by the operation of relay WLS causes the auxiliary line relay WAR to become energized over contacts 0 and d of relay WLR and the line wires 2| and 22, from the source at the location of signal IRA. Relay WAR closes its contact a which causes the auxiliary line relay EAR to become energized over the other signal line circuit from the source at the location of signal 8LA. Relay 5A5 picks up at once over contact a of relay EAR. Relay SASP is operated by relay 5A8 from reverse to normal and closes its lefthand contact 0 which enables switch 3W to be unlocked, while the closing of contact I) of relay 5A8 enables switch 5W to be unlocked. The circuit for relay STER is opened at back contact a of relay 5A5 and relay B'I'ER is not operated.

In the last example the condition of the block signals is checked by the fact that the signal circuits used include front contacts of the approach locking relays ZRAS and BLAS. It will be seen that in accordance with my. invention the condition of the signals is checked even though these circuits are open, due to the release of one or more of the track relays.

It will be seen that the objects of my invention are accomplished in an economical and practical manner with the use of a minimum number of line wires by efiicient circuit design, each of the principal circuits having two or more distinct functions.

Although I have herein shown and described only one form of apparatus embodying my invention, it will be 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 with a stretch of single track railroad having block signals at its opposite ends for governing trafllc movements through the stretch in accordance with traffic conditions therein, each signal having the usual approach locking relay associated therewith the energization of which indicates that such signal is at stop, said stretch including a hand throw switch equipped with an electric look; a switch lock relay, a time element relay, and a stick relay, a circuit manually controllable from one end of the stretch only when the adjacent approach locking relay is energized for operating said switch lock relay, a circuit closed in response to the operation of said switch lock relay when the approach locking relay at the other end of the stretch is energized, for energizing said time element relay, a circuit closed by said time element relay when energized for a predetermined time interval for energizing said stick relay, and a circuit prepared by said stick relay when energized for enabling said electric lock to be energized to unlock said switch.

2. In combination with a stretch of single track railroad having block signals at its opposite ends for governing trafllc movements through the stretch in accordance with traffic conditions therein, each signal having the usual approach locking relay associated therewith the energization of which indicates that such signal is at stop, said stretch including a hand throw switch equipped with an electric lock; a switch lock relay, a time element relay, and a stick relay, a circuit manually controllable from one end of the stretch only when the adjacent approach lockingreleris ener sed .9. lilteb, lock-rela ircuit-chess lemm i -enei n. of. said; switch. 1 c ela whe the an: p ea h. oc in re a at; t eth r: fine. O h stretch i r zeamener z s id time e t la a. ci itclesedby s i me lem nt lay w n e zed fe a; p ed ermined time va o ener z a a d sti k. releme tra k. rcuits s rete. in a normally ene ized. rc lerelai; and we i u ts. p epa d; by. &1. w ch l e re e whe p at d for nablin sa d; lec ri 4.0 t e: e z d. t loc said W h v n m lee-me.- h n c of sai. t. er an t e other lu i a. ntact: closed n y w en sa d eti k' relay isenergize nc binat qnwithiazeir teh f n leees railroad having D190 slgnals'a-t; opposite. nds; for governing trafiic movements through the stretch in accordance with trafilc conditions therein, each signal having the, usual approach locking relay associated therewiththe energization of which indicatesthat the signal is at stop, said stretch including a blind siding having a hand throw switch ateach end equipped with an electric look; a switch lock relay, a, time element relay, and a stick relay, all atthe ma terof one of said, switches, a circuit manually controllable from one end of thestretch only when the adjacent, approach locking relay is energized for operating said switch lock 'relay, a circuit closed in response to the operation of said switch lock relay when the approach locking relay at the other end of the stretch is energized, for energizing said time element relay, a circuit closed by said time element relay when energized for a predetermined time interval for energizing said stick relay, a first track circuit in said stretch adjacent one of said switches, a second track circuit in said stretch adjacent the other switch, each having a normally energized track relay, a plurality of circuits prepared by said switch lock relay when operated for enabling said electric locks to be energized to unlock the switches at both ends of said siding, comprising one for each switch which includes a back contact of the adjacent track relay and one for each switch which is closed only when said stick relay is energized. 4. In combination with a stretch of single track railroad having block signals at its opposite ends for governing trafiic movements through the stretch in accordance with traflic conditions therein, each signal having the usual approach locking relay associated therewith the energization of which indicates that such signal is at stop, said stretch including a hand throw switch equipped with an electric look, a switch indication relay having neutral contacts and a polar contact, a switch lock relay, a time element relay, and a stick relay, means controlled by neutral contacts of said indication relay for preventing the clearing of either block signal except when said indication relay is energized, a circuit manually controllable from one end of the stretch only when the adjacent approach locking relay and said indication relay are both energized for operating said switch lock relay, a circuit for energizing said indication relay including contacts closed only when said switch is closed in its normal position and said electric lock is deenergized and in condition to prevent the unlocking of said switch, said circuit also including pole-changer contacts operated by the approach locking relay at the end of the stretch remote from that from which said switch lock relay is controlled, so

10: amassedhat. died e tlon 3 5 5 polar contact onlyl when such-approach locking relay is energized," a circuit for-said time 'ele'riientfrelay' includ n said polar contact and a Contact dosed by saidswitcli lockrelay when operated, a circuit closed by said time element relay when operated for a predetermined time interval for energizing, said stick relay, and a circuit prepared by said stick relay when energized for enabling said electric lock tobe energized to iinlock said switch,

5 In st-s stem for'tlie" control or an electric lock for adoutl-Y fig trackswitch equipped with anelectric ock and located ina stretch of railway track ov'erwhich traffic movements are governed by block signals at its opposite ends, a switch control relay frianiially controllable from are-1 t' k e or said block. Sign ls a timefleinentfdevice, a track circuit in. said stretch adjacentthe tra switc having a normally en ized track relay, means eon; one by the fr'block sigrial'at stop and'by', said switch control relay when operated for initiaftin'g' the operation of said time element device, and means controlled by Sa d switch control relay when" operated-"for preparing two circuits for enabling" said electric lock to be energized to unlock the track switch, one of said circuits. in

eluding aback contact of said track relay and the other includin 'aj eantaet closed 'in' response to the operation of said time 'eleinent ue'vic'e'ror a pr de r in d ti e n e l 6. In a system for the'control of an electric lock for an outlying track switch equipped with an electric lock and located in a stretch of railway track over which trafiic movements are governed by a block signal, an indication relay, an energizing circuit for said indication relay including contacts closed only when said switch is closed and locked in its normal position, an energizing circuit for said signal including front contacts of said indication relay, a switch lock relay manually controllable from a remote point only when said block signal is at stop and said indication relay is energized, a track circuit in said stretch adjacent the switch having a normally energized track relay, a time element device, and means controlled by said switch lock relay when operated for initiating the operation of said time element device and concurrently preparing two circuits for enabling said switch lock to be energized to unlock the track switch, one including a back contact of said track relay and the other including a contact closed by said time element device a predetermined time after its operation is initiated.

7. In a system for the control of an electric lock for an outlying track switch equipped with an electric lock and located in a stretch of railway track over which traflic movements are governed in two directions by block signals at opposite ends of the stretch, a track circuit in said stretch adjacent the track switch having a normally energized track relay, a switch control relay manually controllable from a remote point only when one of said block signals is at stop, a time element device, means for initiating the operation of said time element device in response to the operation of said switch control relay but only if the other block signal is at stop, andtwo circuits prepared by the operation of said switch control relay for energizing said electric lock to enable the switch to be unlocked, one of said circuits including a back contact of said track relay and the other including a contact closed in response to the operation of said time element device for a predetermined time interval.

8. In a system for the control of an electric lock for an outlying track switch equipped with an electric lock and located in a stretch of railway track over which traffic movements are overned in accordance with trafllc conditions therein by manually controllable signals at opposite ends of the stretch, each signal having the usual approach locking relay which is energized only when the signal is at stop and has been at stop for a predetermined time interval followin its manual return to stop, a track circuit in said stretch having a normally energized track relay, a switch control relay manually controllable from a remote point only when one of said approach locking relays is energized, a time element device, means for initiating the operation of said time element device inresponse to the operation of said switch control relay but only if the other approach locking relay is energized, two circuits prepared by the operation of said switch control relay for energizing said electric lock to enable the switch to be unlocked, the first including a back contact of said track relay and the second including a contact closed if said stretch is unoccupied and both approach locking relays are energized, and means controlled by said time element device eilective when said stretch is occupied for closing said second circuit in response to its operation for a predetermined time interval.

9. In a system for the control of an electric lock for an outlying track switch equipped with 12 an electric lock and located in a stretch 0! tree! over which trafllc movements are governed by opposing block signals, a switch controlrelay manually controllable from a remote point only when one of said block signals is at stop, a'time element device, a stick relay, a manually con-' trollable contact located adjacent the switch and normally locked in the open position, circuits governed by said switch control relay when oper ated effective only if the other block signal is at stop to initiate the operation or said time element device and to energize said stick relay in re sponse to the operation of said time element device for a predetermined time intervalhfind a circuit including said manually controllable "contact and a front contact of said stick relay 1dr controlling the energization of said electric lock to enable the switch to be unlocked.

GEORGE L. TROUT.

References Cited in the file or this patent UNITED STATES PATENTS Number Name Date 1,792,263 Young Feb. 10, 1931 2,018,765 Preston et a1 Oct. 29, 1935 2,019,462 Phinney Oct. 29, 1935 2,241,614 Pelikan May 13, 1941 2,365,344 Judge Dec. 19, 1944 2,367,723 Haines Jan. 23, 1945 2,404,303 Law July 16, 1946