US2550859A - Switch and signal control system for railroads - Google Patents

Description

May l, 1951 c. A. PICKELL SWITCH AND SIGNAL CONTROL SYSTEM Foa RAILROADS 4 Sheets-Sheet 1 Filed May ll, 1946 mxm m22 man mxg k May 1, 1951 c: A. PICKELLv 2,550,859

I SWITCH AND SIGNAL coNTRoL SYSTEM FOR RAILRoAns Filed'uay 11, 194e 4 sheets-sheet 2 L-L .To sAsM aBsM m5 l G) "l u) (n l iz HT', A .L'

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Hrs' ATTORNEY May 1, `1951 c. A. PICKELI.

SWITCH AND SIGNAL CONTROLASYSTEM FQR RAILROADS Filed May 11, 1946 4 Sheets-Sheet 3 3EME HIS /'TTORNEY May l, 1951 l c. A. PICKELL T 2,550,859

SWITCH AND SIGNAL CONTROL SYSTEM FOR RAILROADS @Mij-WH,

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1 r-o-)i T 4NVYP I1:15 @Lo STR STR 111150 1- l 115 ,Jil-41+) 4Rv|vP 1111150 111150121 Tg3 12?. ANW? H15 ATTORNEY Patented 1, 1951 y2.550359 'is'vvireHN [SIGNAL ooNTitoLsYsirEM j'FoaRAILRoAD-s ciarkn. Picke11,'-noehester, N. Y., assigner to GeneralRailway Signal Company, Rochester,

A15p1'iatien-iviay i1, 1946,"seria1'N0- 669.049

defined isv saidto be'within'l-an interlocked group. l

'A routeis 'said to be established Av'vhenthe required positions foreach of the track switches 'for such route are selected in response to 'the joint' designation of -the 'respective' entrance and exit ends of `that routel'by actuation oflthe corresponding'entran'ce and exitbuttons.l fA route becomes set up after 'the track switches-have been p'ower operated to their reduircfd'p'os'itins. In track layouts for congested areasfsuchas subways, for example, where signals are-'placed close together `to facilitate h'andling'ofaflar'ge volume of traiiic, the spacing 'oilthe signals is generally `shorter `than braking "distance of 'fa train, "and therefore the caution-indication of certain .of the signals Yrnu'st'be dependent-limon conditions of occupancyof several track sections in advance of that signal, rather than uponljust the track sections included between that'signal and the next signal inradvanc'e. 'Trackfseetions required to be vunoccupied fori'thecautien'cntrol Vof a signal beyond the' next signal in advance, are' called overlaptrack sectionsffand-a signal that is governed by conditions Tof 'foccupancy in overlap track "sections is said-to lia've overlapy control. SSuchisignal .canlindi'ca'te clear or caution onlyifits overlap track sections are unoccupied.

An object of the present'invention'is to"'pro vide locking for each facing4 point tracks'witch in an overlap section extending beyond lianestablished route. Such overlap locking -isl'c'o'nditional in that it allows Operation of afaeing'fpo'int track switchin. an ioverlapping `ltrack section, only if the track sections included in the-overlap control-extendingover the track switch in its track switchinits normal-'trailingposition. This is desirable in order to prevent damage to'lthe trailed track-switches in lease 4alltrain-overruns the stop signal'at the extendof the established 10ute Another objectof the present invention-isto allow preconditioning-of aroute,A only when'tl'iat route maycall for the power-operation cfa" track y switch thatlis --locked by reason-of overlap '-loeking. Thus such routehcan be` selectedby'route 'establishing In'ieans in response -to i the designation of the respective `'entrar-reeSar-id exit end-s f thatY route,v but such'-l route can' become completely set uponlyaiter -the overlaplockingior anyv 'track 4vswitch includedinthat route-is released. Another object of the ypresent invention--is`-to distinctively vindicateon the-miniature f diagram of the track layout leach -trackswitchy thatf-'is locked 'by Soverlap locking f when a i route# extending lt'nro'ugh---thattrack switch is designated for establishment by the actuation of entrancean'd exit control buttons. 1 1

. 'Another'object of the presentinvention-'is'to distinctively -indicate vthe -lposition v*in Which-1a track" switch is locked by-overlap locking-when a' route extendingy -through that track `switch designated for'establ'ishmen-t by' the vractuation of entrance and exit control buttons. Y

Other o'bjects,purposes and characteristicjfea- .tures-lof the present invention will' be in part obvio'us frein the accompanying drawings and irl-'part pointed out aslfthe descriptionprogresses.

In` descril'oingthe invention indetal; reference Will be' madeto -the 'accoinpanying drawings in which like re'ferencecharacters designatejcorresponcing parts throughout theVseveralillustrations,iin Whichfthose parts having-similarfeatures andfunctionsare designated vlloy* like' letter reference characters fwhich are generally V'made distinctive by reason ofi"1'31'^e`ceding numeralsindicative of their associatin' withvarious switches or signalsgand'in which: Y

. Fig. K l' illustrates '.the ro-ute establishingjmeans provided for the track 'layout jfjfths-ernbodiment ofthe ypresent invention, "together with-'a miniature track 'diagram of such'f-trackllayo't having disposed thereoncontrol buttons. for designation of the' respective entrance andI 'enit ends of the routes; j

Fig. .2 illustrates 'circuit meansprovidedfor causing the '-pcweroperation of the track `switches in accordanceV -with the -'sele'ctionf fof their pesition bythe 'route establishing meansdisclosedu in Big5-1; A

Fig. 3 illustrates the track layout for which this embodiment of the present invention is provided together with circuits involved in the control of typical signals for governing traic through the track layout;

Fig. 4 illustrates the manner of control of approach locking relays for this embodiment of the present invention;

Fig. 5 illustrates the control of electric locking relays for the respective track switches; and

Fig. 6 illustrates circuits for providing overlap locking indications.

For the-purpose of facilitating the disclosure of the present invention as to its mode of operation, the illustrations have been provided principally as schematic wiring diagrams arranged' more particularly to clearly illustrate the mode of operation of the system than to specifically illustrate the structure and arrangement of parts that would be provided in practice. rIhus. the various relays and their contacts are illustrated in a conventional manner, and certain contacts and windings of relays are shown in the conventional written circuit form for the purpose of simplifying the illustrations, each of the contacts being readily identified with its relay by the use of reference characters of that relay above such contact. The symbols and are employed to indicate the respective positive and negative connections to suitable batteries or other sources of direct current, and the symbol (FLI) is employed to indicate the connection through an interrupter to the positive terminal of a suitable source of energy.

Reference is made from time to time during the description of the present invention to the function of parts of the system of a similar nature by reference to letter reference characters common to all of such parts, rather than identifying each part by its preceding numeral which is generally characteristic of the particular switch -or signal with which such part is more directly associated.

Track layout-The track layout used for this embodiment of the present invention as shown in Fig. 3 is selected as of a character to facilitate disclosure of the principles of operation of the system provided by the present invention, and it is to be understood that the present invention is not limited to the specific track layout shown in this embodiment of the present invention. It will be readily apparent as the description progresses that the principles of operation described withrespect to the specific track layout shown are readily applicable to other more complex track layouts to be encountered in practice.

With reference to Fig. 3, the track layout of this embodiment of the present invention comprises two parallel main tracks interconnected by Crossovers 4, 5 and 6. The upper of the two tracks is divided into track sections including sections 2T, 3T, 4T and 5T; and the lower of the two main tracks is divided into track sections including track sections 6T, 1T, 8T and 9T.

Signals are provided for governing entrance to each of the routes for trafc in both directions, the signals II, I2', I5 and I6 being provided for governing eastbound traic, and the signals Il, I8, I3 and I4 being provided for governing westbound trafc. The signals shown are assumed to be of the searchlight type having electrically operated signal mechanisms of the type shown, for example, in the patent to O. S. Field, No. 1,835,150, dated December 8, 1931.

The signals are of the three-indication type having red, yellow and green color light indications for the respective stop, caution, and proceed or clear indications. It is understood that other types of signals such as color light signals having individual color lamp units, position light signals, or semaphore signals could as well be used in accordance with the requirements of practice.

The track switches are power operated by suitable electrically controlled switch machines which may be of the general type, for example, as is disclosed in the patent to W. K. Howe, No. 1,466,903, dated September 4, 1923. It is to be understood that the switch machine motor is controlled in accordance with the usual practice to provide suitable overload protection and other protective features generally required in practice.

As a means for repeating the positions of the respective track switches, the track switches of each crossover have associated therewith NWP and RWP neutral relays for repeating the respective normal and reverse positions of such track switches. rhese relays are controlled in accordance with the usual practice, and for the purpose of simplification of the present disclosure, the control of these relays has been merely indicated by dotted lines to show that a pair of relays is associated with each of the respective Crossovers. It is therefore provided that each of the relays NWP is energized whenever the track switch or track switches with which it is associated are in their full normal positions, and similarly each relay RVIP is energized when its track switch or track switches are in their full reverse positions.

Control machina-A miniature track diagram is provided on a control panel on the control machine corresponding to the track layout for which the system is provided, such diagram being illustrated in Fig. l. The respective entrance and exit control buttons are disposed at positions along the miniature track diagram corresponding to the respective entrance and exit ends of the routes as dened by the location of the signals of the track layout. Although separate entrance and eXit buttons are shown for the respective entrance and exit ends of each of the routes for designation of such ends in the establishment of routes, it is to be understood that single buttons performing the function of both entrance and exit designation, dependent upon the sequence of operation of the buttons, can as well be provided if such are the requirements of practice.

It is to be understood that suitable indicating means is provided on the miniature track diagram to provide all of the information necessary for an operator to intelligently cause the establishment of the various routes, but, for the purpose of simplication of the present disclosure, only certain of the indicator lamps associated with indications concerned with overlap locking are shown. It is to be understood that vari-- ous well known types of indicating means can be provided on the miniature track diagram in accordance with the requirements of practice, such, for example, as indicating means of the general character disclosed in the patent to T. J. Judge, No. 2,298,946, dated October 13, 1942.

System devices.-Entrance and exit relays NR and XR, are provided for the ends of the routes to be responsive to the manual designation of such ends in the establishment of routes. Each of the entrance relays NR is provided with a stick circuit so as to be maintained picked up after it is energized upon the actuation of its entrance button NB, such stick circuit being pro- ,of the present disclosure. standing of the present invention, it is believed Thus, for an undersucient to consider the general mode of operation of the system in route establishment, and the manner in which the mode of operation as disclosed in the above mentioned Judge patent is modified by the present invention. For the purpose of facilitating reference to that patent, the numbering of the switches and signals, together with letter reference characters of the present disclosure, has been made to agree with that patent.

The route establishing means in general comprises an initiating circuit network for each direction of traffic, and a completion circuit network which is effective to energize switch position selecting relays for either direction of traiiic.

Each of the initiating circuit networks is a circuit organization having a structure that is readily comparable to the track layout for which the system is provided in that there is a circuit portion corresponding to each of the main tracks, and another circuit portion corresponding to each of the crossovers. The ends of the initiating circuit networks corresponding to the entrance ends of the respective routes serve as energy feed points for the networks, energy being applied at such points in accordance with the respective designation of such points as entrance points for routes to be established by the actutaion of the respective entrance control buttons NB.

In response to the actuation of an entrance control button NB by an operator, an entrance relay NR is picked up for that entrance point, and such relay is maintained picked up by a stick circuit, in a manner corresponding to that fully described in the above mentioned patent to T. J. Judge.

The application of energy at the feed points of an initiating network causes energy to feed through the circuit branches of the network corresponding to the respective available routes emanating from that entrance point. Such energy feeds through the initiating network to the respective exit relays E associated with the routes that are available for establishment at that time v to condition such exit relays in a manner to allow the picking up of one of such relays if an operator actuates the exit control button XB associated with that exit point. It is further provided that energy feeding through the initiating network picks up a switch position selecting relay AY or '1 BY for each track switch that is trailed in a normal position from that entrancev point to condi- 3 tion the completion circuit network.

The completion circuit network can also be said to have circuit branches corresponding to the re- ;spective tracks and Crossovers of the track laylout, and such circuit network has feed points corresponding to the respective exit ends of the iroutes for both directions of traffic where energy can be applied to the circuit network by the picking up of the respective exit relays XR,

As a specific example of how a route can be established, it will be assumed that it is desired to establish a route from the signal i2 to the signal I6, signal l2 being a signal having overlap control. Inasmuch as the overlap control of signal l2, as indicated by the arrow l5 of Fig. l, erw;- tends through the track switch EBW in its normal position as a trailing switch, it is required that the track switches of crossover 5 be operated to their normal positions as a part of the establishment of the route from signal i2 to signal I6, although the crossover 5 is not included in the route under consideration. The reason for this operation is to protect the track switch at the lower end of the crososver 5 against damage in case a train passing over the route from signal i2 to signal IE should overrun the signal i6. It is thusI provided that the establishment of a route must include the power operation of each trailing track switch included within the overlap control limits of the signal governing entrance to the route desired to be established. It is further provided that the route cannot be established unless each of the trailing switches which would be included within the overlap limits of control of thc signal governing entrance to the route must be free to be operated to its normal position before the route establishing means can become eiective to establish the route. That is', subsequent to the designation of the entrance end of a route at signal i2, the designation of an exit point for the route by the depression of the exit button MXB cannot cause the establishment of that route, even though it is available, unless the track switches of the crossover 5 are free to be operated to their normal positions.

The picking up of relay I2NR in response to entrance designation at the entrance to the route governed by signal I2 applies energy to the initiating circuit network for the establishment of routes for eastbound trains and causes the picking up of the relay 4BY, because the track switch ISBW at the lower end of the crossover i is trailed in such route in its normal position. The relay BY is energized under such conditions by a circuit extending from including front contact 46 of relay I2NR, back contact 47 of relay MXR, back contact 48 of relay 4R, and winding of relay BY, to

The picking up of relay 4BY closes a portion of the initiating circuit network to condition the relay MXR so that it can be picked up in response to the actuation of the exit button MXB. The circuit by which the relay MXR can be picked up under such conditions extends from including front contact 46 of relay IZNR, back contact 41 of relay IZXR, back contact 48 of relay llR, front contact 49 of relay llBY, back contact 50 of relay 5RWZ, winding of relay Mlm, back contact 5| of relay MNR, and contact 52 of the exit button MXB, to The picking up of relay MXR establishes a stick circuit at front contact 53 to shunt the contacts 5I and 52 of relay MNR and the exit button MXB, respectively, out of the circuit just described. It will be noted that the back contact 5U of relay ERWZ is included in the circuit just described for the relay MIB. Such contact checks that the track switches of the crossover 5 are free to be operated to their normal positions, if they are not already in such positions.

The picking up of the relay MXR is effective to pick up a relay SNWZ for causing the power operation of the track switches of the crossover 5 to their normal positions as shown in Fig. 2, and as hereinafter described. After the relay 5NWZ is picked up, a branch of the completion network is closed to provide for the energization of relay BN for selecting the normal position of the track switches of the crossover 4 as required in the route under consideration. The relay 4BN is picked up under such conditions, in accordance with the energization of the relay dBY, by the energization of a circuit extending from including front contact 54 of relay MXR, front contact 55 ofA relay 5NWZ, front contact 56 of relay 4BY, and upper winding of relay 4BN. to

attesta from signal l2 to signal 'l`6f` Although a simple 4track layout has been chosen for a `disclo's"1re of "the operation of the system acsordin'gtoL the present invention, it is believed thatitwillbe readily apparent that the same systemqcan rbe applied in the lselection of routes requiringlthe'positioning of a larger number of trackl'switches'in accordance'with the general principles frute establishment as has been specifically pointed out in the,A above lmentioned prmlpatent to T. J.y Judge.

Upon considering theicircuits as they have been described, itwill be apparent'that the back contact; 501 of relay SRWZ in the initiating lcircuit network for the establishment of routes for eastbound trains is in a circuit portion o'f the network-f'that'is common Vto the establishment of routesl extending' tojthe exit` point at signal I 6 from signal I2, or from signal l l over the crossovill., This, ofcourse, is'desirable because it is required that the vtrackvsw'itch 5BW` be"operated to' 'its normal position whenever it is included, as aiswtch trailed in its norinal'position, inthe overlap portion ofthe control of a'nysignal.

yThe relay yl 4XR is conditioned` for energization by,.thefinitiatin'gfnetworki when the entrance buttqn 'IVINBis" actuateclfc'irthey designation of an entrance point, so`a`s` lto` provide that such relay caribe picked up upon the' subsequent designation ofy `the exit en'd'of'the route by the actuation offthefe'xit button MKB.' The circuit is closed the track switchesto ,free them of obstructions and for other purposes 'withoitrequiring Athe establishment of routes. u Reference is-tobenade to the above mentioned patentlto'T. 2T. Judge for a more completedisclosure of the mode of operation ofl the" system in response to the "positioning of the auxiliary switohcontrol levers.H The picking 4up of relay'liBNin the establishment of a" route from signal'i2fto'signal'l'ina manner which has been described, 'isH effective to causethe picking up of the relay `lNlVZ'mr energizing the switch machines'SM of the 'track switches of the crossover `4` with va polarity to operate such track switches to their normal'positions.` IThe relaylNWZuispicked up under such conditions bythe |energizationof a" circuit eX- tending 'from' (+5, incmdin'gffroht cotct se uponfthe depressiono'ffbntton MXB extending from (4%); including? frontfr contact 51. of relay tactv 59;,f *relaylllANfba-ck contact 6i!V of relay 43N, back contactdllof relay BY, back contact 5090i Arelay BRWZ, winding 'of relay IliXR, back contact'l" of .relay I 4llNR, and contact' 52 of the enit button IAXB, to (-)1 It is provided in asimilar manner that the track switches of the crossover 6 are operated theirnorin'al positions in accordance with the establishment of a route frornsignal i l to signal 1 5, because the track switch 6AW at the upper end` of the crossover B is required to be trailed in the, OYQl'lp poldol?Y 0f the CQQUOI 0f Signal; 5 l when such route isestablished.v Thus, the'inclusion of the back contact 6 I` of relay SRWZ, in the circuit branch of the" initiating circuit used in the establishment of `a route from signal li to signal lchecks that the track switches of the crossover 6V are free to be operated'to their norma] positions. After the relay ISXR/has been picked u p the relay v6N WZ isl picked` up as shown in Fig. 2 I

alldas hereinafter described. The picking up of relay GNWZ conditions a completioncircuit by Vllhhthe relay 4Al\l can bepicked up for selecting the normal positions ofthe track switches of the ycrossover llr to provide establishment of the desighated .IQl'lte- The relay FAN iS Sheff-*ized by an obvious circuit under such conditions, including front Contact 62 0f relay @NW2- Switch controle-The power operation, of the 4 varioustrack switchesv in accordance with the picking up of the relays AN, BN' and R1 in the establishment `oftlne routes isfprovided` as shown in Fig. 2, although it will. be readily apparent to thoseskilledk in the art that various modied means Ofswitch control can be provided in accordance with` the requirements inpractice. It is alsoirrgriieathetthe traQkSWiwhGs 0i each af the @roster/ers are power Operated in leSrQnSe t0 auxiliary SWi'l.f @12H01 lel/e'l PrOVded, for the of relay'BN, back contact '64 f relay 4R,wind`- ing of relay 4NWZ, and fronteontact 6510i relay 4L, to (4). The inclusionfof :front contacted of relay l{lLin the circuit just described provides thatj the relay lllSTWfZk can be"picked upffor'the power operation of the track switchesonly if it is safe to operate Vthe track switches'according to the lelectric locking; vIn'fa''cco'rdance Withthe pickingrup'ofthe'frelay 4N`W'Zr,ven'ergy `is applied at front contact dii` to the'switch operating circuits of a polarity to operate the switfchhniachines to their normal positions.L '5 A If an established route calls fer the operation of the track switches of the crossoverfltotheir reverse positions, theA relayfiR/iswpickjed` up in the establishment ofV the route in the manner which has been discussed, "andthe picking up of that relay causes the picking up oi'therelay aRVF/Z i0 apply Power .te'tlie'sw'tah nahhesfor the tfafzkwit9h9`a-0ff the .COSSfQver 4 0f, a rola-rity toA operate suchswitch'machines to their reverse positions. Thus the picking'up oi'relay 4R is effective to cause the energiz'ation'of relay tltWZvupQnuthe closure of anci'rcuit extending frein `inc111lis freni connetl @fi relay 4R, backcontact Gofrelay ABN, back contact 69 ofrelay 4AN, winding of relay ARWZ, and frontl cjon'tactf'Sf of fthe lock relay 4L, to (l-)Q "Ihe closure offront'contactk'l ofthe relay 4RWZ appliesenergyto the control circuit for the'switch rr'iachiries'l to provide for their operation to their'reverse positions.

A siinilarwInodel ofwoperation is effective in positioning the track switches of the crossover feXoe/pt that such crossover'isrincluded in the overlap" control" section offthe` signals rIl and l2 and therefore is subject to overlapulocking as is provided by the inclusionwof frontfcontact 'H of relay ELO infthe'pickup circuits forvv the relayslN'WZl and BRWZ. Y

It is also provided that the relay ENV/'Z has a pickup circuit dependent upon the closure of front contact 72, ofrelay MXR, because the track switch 513W of the crossover 5 becomes a trailing Swine. in @Weder wird Section for a Signal governing entrancete a route having an exit nointatsignal I5, Thus, whenv a route is established for, eastbound traine, withsignal I Eivas the exit point, the relay MXR is picked-up, and the .pickingvupiof thatfrelay causes the energization il l network in a manner which has been heretofore described.

In a similar manner the closure of front contact of relay I3XR causes the picking up of the relay BNWZ to operate the track switches of crossover 6 to their normal positions in accordance with the track switches EAW at the upper end of the crossover 6 being included as a trailing switch in the overlap control section of the signal II.

It will be noted that a stick vcircuit is provided for each of the relays NWZ and RWZ for the purpose of causing the completion of the operation of a track switch when such operation has been initiated. The relay QNWZ, for eX- ample, has a stick circuit which is closed, when the track switches of crossover 4 have initiated their operation from their'reverse to their normal positions, to provide that the track switches will complete their operation, even though the route establishing means may be restored before the operation of the track switches has been completed. YThus, the relay tNWZ is provided with a stick circuit extending from (-I-), in-

cluding back contact IS of the normal switch repeater relay iNWR front contact TI of relay ANWZ, back contact 6d of relay 4R, winding of relay 4NWZ, front contact It of relay NWZ, and back Contact I9 of relay RWZ, to

t will be noted that the stick contact 'I8 of relay dNWZ shunts the lock contact 55 of relay 4L out of the circuit to provide that operation of the track switch will be completed, even though the lock relay 4L has been dropped away in mid-stroke. In a similar manner the closure of back contact 8i) of relay RWP in the stick circuit for the relay ARWZ is effective to cause such relay to remain picked up until the track Switches of crossover 4 have completed their operation to their reverse positions.

After the track switches of a crossover have completed their operation to the position called for by the relay AN, BN or R of the route establishing system, a correspondence relay NCR or RCR is picked up to indicate that the track switches of the crossover are in correspondence with the required position for the route established. These relays repeat corresponding positions between the switch control relays NWZ and RWZ and the switch position repeater relays NWP and RWP. The relays NWP and RWP are steadily energized in accordance with the positions of the track switches of the crossover with which they are associated, while the relays NWZ and RWZ are picked up only for the track switches that are included in established routes. Thus, when a route is established through the track switch IBW at the lower end of the crossover 4 in its normal position, the picking up of the relay 4NWZ causes the picking up of the correspondence relayV QNCR after the track switch has beenproperly operated to its normal position. The relay ANCR is energized under such conditions by a circuit extending from (-1-) including front Contact 8i of relay IINWZ, front contact 82 of relay 4NWP, and winding of relay dNCR, to In a similar manner the relay 4RCR is energized when Ythe switch repeater relay llRWP is picked up in correspondence with an established route. The circuit for relay RCR-extends from including front contact 83 of relay ARWZ, front contact 84 of relay tRWP, and winding of relay IIRCR, to It will be readily apparent that a similar means of control is provided for l2 Y the correspondence relays associated with the Crossovers 5 and d.

Signal controla- Having thus considered the manner in which routes can be' established in ac'- cordance with the designation of their respective' entrance and exit ends and how the track switches can be power operated to set up such routes, consideration will now be given to-the manner in which the signals are controlled for governing entrance to the routes that have been` set up.

The signal control relays G for the respective signals are energized from a signal control circuit network organization including contacts of the switch correspondence relays NCR and RCR and track relay contacts to check that the established routes are unoccupied by trains. The inclusion of the switch correspondence contacts in the signal control circuit network provides that the signal control relays can beV picked up only after the tracks switches have been properly positioned in accordance with the designated routes. As a specific example, the signal control relay IZG for the control of signal I2 is picked up when a route is established from signal I2 to signal I6 after the track switches of the crossover li have been operated to their normal positions to provide for the picking up of the correspondence relay NCR.

Inasmuch as the signal I2 has an overlap control as indicated by the arrow beneath the miniature track diagram of Fig. l, energy for' `the control of the relay E2G must feed throughl a circuit network including track contacts of thek respective overlap track sections. It is, there-- iore, required that the relay I2G check that the track sections are unoccupied from the signal I2 to and including the track section 9T (if the track switches of the crossover 6 are in their normal positions), or to and including track section 5T' (if the track switches of crossover 6 are in their reverse positions). Thus, assuming the track rswitches of crossover 6 to be in their normal positions, the relay IZG can be picked up when a route is set up from signal I2 to signal I5 by the energization of a circuit extending from (-1-), including front contact 85 of relay STR, front contact 86 of relay ATR, front contact 8l of relay STR, front contact B8 of relay BTR, front contact B9 of relay NCR, front contact 90 of relay MXR, front contact 9i of relay TTR, back contact 92 of relay 4RCR, front contact 93 of relay llNCR, back contact 9G of relay I2XR, front contact 95 of relay I2NR, and winding of relay I2G, to It will be noted that the inclusion of the front contact 89 of relay 5NCR in the circuit just described checks that the track switches of the crossover 5 have been operated to their normal positions, because the lower track switch 5BW of that crossover is included as a trailing switch in the overlap control section of the signal i2.

-If the track switches of the crossover 6 are in their reverse positions at the time when the route is set up from signal I2 to signal I6, the relay I2G is energized by the circuit just described, assuming that the overlap portion of the trackway is unoccupied by a train.

It will be apparent from the circuit organization of the signal control network that the overlap control or" signal II is dependent upon the same track contacts and the correspondence contact 89 of relay 5NCR for the establishment of a route from signal II to signal I6 over the crossover 4. More specifically, with the track switches ofvthe. crossoterfan atheirfrncrmalrpof. sitions. the relay...| IG is energized` after: a, route isset up from, signal.; I L tofsignal I Ii by a, circuit extending from including rontcontact 85 of. relay 5TRfront contact-,.86 lof.relay. -1IT1'1 front contact 8l of relayTR, frontcontact of. relay STR., front .contact 89 -of ,relaytNClA front contact $0V oirelayMXR, yfront contact V9|. or" relay `'|TRfront contact 92. of .relay 4RCR,.back contact4 99- of relay 4NCR, frontcontact |00 of relay,.3.TR, back-contact |0I. ofrelay ||XR,`and front contact |02 of relay IINR, and winding of relay HG, to

If the track switches of thevcrossover S are in. their reverse positions when a route. is set up `from .signal I I to signal I6 the relay HG is energized by the circuit just described, assuming. that the overlap portion of the trackway is unoccupied by a train.

Upon considering the circuitsy that havebeen described, it will be. noted that track relay contacts of the track Vrelays associated with the overlap .trac-k sections of both tracks have been includedA inthe circuit, andit is provided that certain of such contacts areshunted inaccord ance with the positionscf thev track switches ofthe crossover` 6. Thus the `contacts B5 and 8610i relays IlTR, and 5TH. need notbe included in the circuit .ifthe; track sv/itchesof crossover Ii are in their lnormal .positions and therefore such; contacts. aregV shuntedfby. front contacts 98 of relay 6NWP,.simi1-arly if thetrack switches of the crossover are in their reverse positions, the front contact 'I' of relay STR need not be included in the circuit, so it is shunted by front contact I08of relay ERWP. Bythis circuit arrangement the operationy of the track. switches of crossover 6 when; the overlap track vsections of both tracksare upoccupied can be accomplished without flashingieither signal II or signal I2-if such signal iszclear at that time.`

l.. au

The organization ofv thesignalcontrol. circuit network-is lsuchthat the` circuit for the relay II G includes thefront contact |03 of relay ENGR when the route is established from signal il to signal I5, with the track switchesof the crossover 4. in their normal positions, because the trackswitch SAW at the upper end of `the crossoverf becomes a `trailing switch underV such cond-itionsv in the overlaprcontrol section for the signal II. Thus, assuming thetrack, switches of the crossover 5 to be in their normal positions, the signalcontrol relay I lG'is energized fora route set up from signal to signal |51 by a circuit extendingfrom (4a), includingfront conv tact Sti-of relay QTR, front contact 'l of relay STR, front contact |04 of relay STR, front contact .|05 of relay tTR, front Contact |03 of re. lay BNCR, front contact |06 `of rela-yl lSXR, back contact Il1 of relay 4RCR, front contact 9S of relay 'INCR, front contact YI 00 of relay TR, hack 'contact IUI of relay MXR, frontcontact |62 Switchesf, ,crossovetfare their normal-,posici tions. Thecontact |04 yof .relay STRisshurited. by contact Mill oil-,relay SRWBwhen the track. switches of the. crossover. 5 are inotheirreverse, positions because theY tracksectionf'l is4 not,l

switchesY arenot power operated in accorda-nee,

with an established route. On, theother hand, it wilLbe, noted that contacts of-thecorrespond-- ence relays NCRare. used in the. circuit Vnet-v work for checking the normal positions of the track ,switches that. are.trailing. inthe overlap,v portion of theI signal control circuits, thuscheck; ing thatthetrack switches have been.,` properly positioned in, accordance. withtheir. posit'ijons.4 called for by the route establishing.,meansbee fore the signal governing entrance to `.the lroute can becleared.

Inasmuch as only certain of y. thesignals which are for governing relatively highspeed traino are provided with overlapcontrol,` onlythe signals il and I2 are assumed to,` hayeoverlale control provided, and the other. signals. are., as@ sumed to be. controlled in f a` manner -correspond,eY ing to that fully described inthe `above.,mentioned patent `to T. J. Judge to whichreference -I is to be made for a disclosure as ,to the manner iny which this control is accomplished.

being the case,I the relay IBG for thea control of.

signal I3, forI example,Y is shown as not requiring. an overlap control circuit, and, thus such, relay oan,.be picked `upwhen a..,route..is setup from signal I3 to the exit point at signal 'I I, energy being applied to` the circuit for the11 2-`y|3 3 at front contact IUI of therelay- I IXR..

In accordance with. the` picking up of a signal control relay G, energy is applied throughcontacts of that relay to a circuit for energizing the. mechanism of the searchlight signal with which that relay is` associatecLothe` polarity of energization of such mechanism being selected in accordance with the condition of the next-signal in-advance ac cordingto the usual practice.` Thus, the picking up of the relay I ZG, for example, causes theenergization of the mechanism of singnal I2` upon the closure-0f front-Contacts@ and Il@ witha polartyaslseletedby the. C911.- tacts I and. IdZof` the relay lllYGP, The relay I AYGB ispicked uponly when the mechanism of signal I4..is. operated to` its cautionor-clear indicating position.

Electric Zockz'ng..-Although Various forms of electric locking can be used with the system prof vided by the present inventiom'the electric locking circuits illustrated in Figs. 4 and 5 have Ybeen chosen for ,this` disclosurebeoause .they 1are particularly applicable .to theconditionls. under` consideration where the signals are. spaced close. together, andgthus overlaplockingfor someoi the signals is required.. Itis to be understood, how-V ever, thatthe. electric locking. may. he modied as required to. t the-requirements of practice.

In accordance with the 0195esnatins 0f, the signalait is-generally'provided thats-.Small ber of track SwitchesY are required t0 ,0 honed: in. any route tok @established um or@ sisnaltf.)` the next sienalinadvance.. Thus, ,there is little to be gained by the use of rear release route locking such as is disclosed in the above mentioned patent to T. J. Judge, and there are some advantages in connection with the safety of operation of trains to be obtained by having the locking effective for each entire route until such route becomes entirely unoccupied in the rear of a train.

As a consideration of the mode of operation of the electric locking it will be assumed that the signal I2 is cleared for a route set up from that signal to the signal I6. In accordance with the clearly of that signal the signal repeater relay I2RGP is dropped away, and the dropping away of that relay opens the circuit for the relay IEAS (see Fig. 4) at front contact H2, and also opens the circuit for relay IZASO at front contact H3, to cause those relays to be dropped away. The inclusion of contact H4 of the relay I2AS in the circuit for the lock relay 4L provid-es that such lock relay is dropped away to lock the track switches of crossover 4 upon the clearing of the signal I2 governing entrance to the route including the track switch GBW.

The relay 5LO is the overlap locking relay for the crossover 5, and although the clearing of the signal I2 governing entrance to the route from signal I2 to signal I6 does not cause the dropping away of the conventional switch lock relay 5--6L, the overlap lock relay 5LO is dropped away upon the clearing of that signal by the opening of its circuit at front co-ntact 4I of relay IZASO to lock the trailing switch EBW at the lower end of the crossover 5 in its normal position.

The locking of the track switches of the crossover 6 in accordance with the clearing of signal I2 is conditional in that the track switches of crossover 6 should be fre-e to be operated to either position when the operation of such switches cannot throw the overlap portion of the control l of signal I2 onto an occupied track section. That is, for example, if the track switches of the crossover 6 are in their normal positions when the signal I2 is cleared, and the track section 5T is occupied by a train on the upper of the two main tracks, upon a consideration of the signal c-ontrol circuits (see Fig. 3) that have been heretofore described, it will be readily apparent that the power operation of the track switches of the crossover 6 to their reverse positions would be effective to select the track section 5T as being included in the overlap control portion of the circuit for the signal control relay I2G, and if such track section were occupied by a train, the signal I2 would be put to stop. Such control of the signal I2 would be undesirable and unsafe. It is, therefore, provided that the electric locking for a facing point overlap track switch is so arranged as to lock the track switch only when its operation would cause the signal involved to be put to stop by selecting a branch of the signal control circuit containing a deenergized track relay.

' To consider the circuit means for accomplishing the above described mode of operation, it will be assumed that the signal I2 has been cleared and that the trackway in advance of that signal is unoccupied, either with the track switches of the crossover 6 in their normal positions, or in their reverse positions. Under such conditions, with the track sections 5T and 9T both unoccupied by a train, the overlap locking relay LO is maintained energized by a circuit extending from including front contact H5 of relay I IASO, `front contact H6 of relay STR, front contact II'I of relay ETR, and winding of relay GLO, to With relay ELO maintained energized, and with the relay 5-BL picked up, it is provided that the track switches of the crossover S are not electrically lock-ed, and therefore can be operated as required in the setting up of routes. This is true because the closure of front contacts I IS and H9 (see Fig. 2) of the relays 5-BL and SLO respectively in the pick-up circuits for the relays SNWZ and SRWZ allows either of such relays to be picked up for operating the track switches of the crossover 6.

Assuming again that a route has been set up from signal I2 to signal I, at a time when the track switches of the crossover are in their normal positions, and the track section 3T is unoccupied, it will be further assumed that the track section 5T is occupied by a train, and therefore if the track switches of the crossover t were operated to their reverse positions, the track section 5T would be included in the overlap portion of the control of signal l2, and such signal would be put to stop. It is therefore desirable under such conditions that the track switches of the crossover be locked in their normal positions when the track section 5T is occupied by a train. Such locking is provided in the control of the relay LO as shown in Fig. 5 in which the front contact II'I of relay 5TH is opened, and the front contact I2il of the relay GRWP connected in multiple with that track contact is open because the track switches of the crossover E are in their normal positions. Thus, assuming the approach locking relay IZASO to be dropped away at that time because of the signal I2 being clear, the relay ELO remains dropped away, and the opening of front contact H9 of such relay in the circuits for the relays BNWZ and SRWZ as shown in Fig. 2 prevents the picking up of relay ERWZ for the power operation of the track switches of the crossover 5 to their reverse positions.

Similarly, it is provided that if the track switches of the crossover 6 are in their reverse positions to provide that the signal I2 is cleared by an overlap control extending through iront contact HB8 of the relay ERWP (see Fig. 3) at a time when the track section QT is occupied by a train, it is provided that the track switches of the crossover are locked in such reverse positions, because the relay IiLO is dropped away due to the opening of contacts H, I2I and i22 of relays STR, SNWP and IZASO respectively (see Fig. 5). Thus, the relay 5L@ is maintained denergized under such conditions to open the pick-up circuit for the relays @NW2 and SRWZ at front contact H9 to prevent the picking up of the relay ENWZ for changing the position of the track switches of crossover 5.

The use of the contacts I2il and 12| of the relays GRWP and GNWP connected in multiple with the contacts Hl' and H6 of relays STR and STR respectively, in the circuit for relay SLO, provides that the track switches of the crossover E5 are free to be operated when the track switch BBW is a facing point switch in the overlap control of signal Ii or signal I2, ii' its position selects a portion of the overlap control of either of such signals as including an occupied track section 5T or 9T to prevent the clearing of either of such signals. This is, assuming that a route is set up from signal I2 to signal I, and the track switches of the crossover t are in their reverse positions with the track section 5T occupied by a train and the attacco 'track section' 9T unoccupied, 'the 'inclusion of front contact |20 ofrelay GRWP in multiple with front contact I II ofk relay STR in the circuit for relay 6LO provides that the track switches of the crossover 6 can be unlockedv under such conditions, irrespective of the condition of the 'approach and time locking relays IIASl 'and IZASO, to allow kthe track switches of the crossover to be operated to their normal positions and thereby allow the signal I2 to be cleared. Although the relay SRWP is dropped away as soon as the track switches of the crossover start their operation to their normal positions, the dropping away of the relay ELO is not `effective to prevent the complete operation of 'the track switches because of stick circuits provided for the relays GNWZ and 6 RWZ in a manner heretofore described when considering more specifically the organization of the switch `control circuits.

It will be noted that a similar mode 'of opera tion is effective when the track switches of the crossover 6 are in their normal positions, and the track section 9T is occupied 'by a train to allow the lock relay SLO to be energized by a circuit including front lcontact I2I of relay GNWP, and thereby provide that 'the track switches of the crossover can be operated to their reverse positions, and yin that manner select the overlap control of signal I I or signal 4I2 through the track section 5T, which may be unoccupied at that time. Having thus described specific conditions involving` the overlap loc-king of the facing point switch .BBW of the crossover 6, it is believed to be readily apparent that similar conditions apply to the locking of the Y track switches of the crossover Elwhen a route is set up from signal II to signal .|5, the relay SLO being provided as an overlap locking relay for the crossover 5 and being ycontrolled in a manner similar to that which has been specically described with Arespect to the control Aof the relay ELO because the switch `EAW is a facing point switch with respect to that rou-te.

To consider a specific example of the manner in which the overlap locking of the track switches of crossovers `5 and 6 is provided in accordance with the establishment of a .route lfrom signal I I to signal I5, it will be apparent that the Str-'ack switch SAW at the upper endv of crossover 6 becomes a trailing switch in the overlap section 4T with respect tothe signal I'I, land therefore the relay SLO is dropped away upon the dropping away of the relay I IASO in response to the vclearing of signal II, except when the track switches of the crossover 4 are operated to their lreverse positions for the establishment of ya route from signal -II to signal I6. Thusl in the circuit 'for relay 6LO, the frontcontact II5 of relay I-IA'SO interrupts the circuit `for relay ELO, except when the relay IIRWP is picked up, to close front contact I 23 at a time when the track switches of the crossover 4 are operated to their reverse positions. The locking of the facing 'pointswitch EAW is provided in a similar manner to that heretofore described with respect to the locking of the track switch BBW, the relay ELO being energized dependent upon the closure o'f ffront contacts 43 and 42 of the track relays for the overlap track sections 5T and 9T respectively, except when such contacts 'are shunted by the respective front contacts |24 and |25v 4of relays SNWP and v5RWP, corresponding to the positions of the track switches of crossover yi5 required for routes extending to and including such overlap track sections.

' 18 Restoration vrifo normals-Generally speaking nthere. are two means by which the route establishing means may be restored to normal, one ybeing the means effective bythe slotting of the signals upon passage -of tra-ins, and the other -being by manual designation of routes to be restored by the actuation of `the respective entrance buttons NB for the entrance jends of `such routes to restorationv positions. This can be *accomplished in general 'in fthe manner 'fully described inthe above mentioned patent lto AT. J. Judge.

To considera typical example y'of how restorat'ion can be Yeffected by manual designation, it will be assumed that a route is 'setup as has been heretofore described from signal I2 to signal I6, and that 'it is desired ltocause the restoration to normal ofthe parts lof the system associated with the establishment and setting up of that route. To initiate such restoration the operator actuates the entrance button II2NB vto its restoration position and lcauses Vthe Adropping away of the relay IZNR. as vspeciiically described in the above mentioned patent to T. J. Judge'.

In accordance 'with the dropping away of relay I ZNR, the opening of front contact d5 of that relay (see Fig. l) opens the circuit by which the relay MXR has been maintainedrenergized, and thus causes the dropping away Vof that relay. The relay IAXR in Adropping away opens vthe pick-up circuit for 'the completion network by ywhich the relay 4BN has been energized at front com tact 54, and it also opens the circuit for'the relay SNWZ (see Fig. 2-9 at front contact 'I2 to Ycause that relay'tobe dropped away.

With reference to Fig. 23,' the lsignal I2-is put to stop subsequent to the dropping laway of the entrance relay I2NR because `of the 4opening of front lcontact 9'5 --of V.that relay. The dropping away of the relay IZG( opens the circuit forsignal I2 at front contacts 109 and IH] to deenergize the mechanism of 'that signal and thuscause such signal to be lput to stop. vThe restoration to stop of the signal 'I2 causes the picking up of the signal stop rep-eater relay I2RGP, and the picking up of that relay closes a circuit `for 'picking up there'lay IZAS (see Fig. 4) (assuming that the approach track section GTR is unoccupied) extending "from K+), including front contact II2 of'relay I'ZRGP, front contact 12B of relay 16TH., and' winding 'of relay HAS; to I'f, however, there is a train in approach of the signal I2 lso as to cause `the relay STR 'to be dropped away, it will be Vrequired that the 'thermal relai'r 12TH be operated to pick up the relay I'ZAS in accordance with the usual 'practice as fully described inthe 'above mentioned patent to T.AJ. Judge. It is 4also provided'that the relay I Z-AS can be restored immediately upon passage ofA a tra-in in a manner to' be hereinafter considered. It is also provided that the relay I 2ASO, which is associated with the overlap locking, is immediately restored' under the above .assumed conditions, 4such restoration requiring that the track section in the rear and in advance of the signal I 2 bel unoccupied in order that -such relay may be immediately restored. Thus, the 'relay IZASO is restored upon the picking up lof the signal repeater relay :IZRGP -by a circuit-extending from -(et), including front :contact `lli-I of relaxr I 2RGP.,V front contact 121 'of' relay TTR, front .contact |28 of Vrelay GTB., and winding of relay lI2ASo., Lto f( Should either of fthe ltrack sections 6T or CIT be occupied 'by -a train, it is required that l"the :relay Ifznsobe-picked up only 19 subsequent to the operation of the thermal relay .I2TI-IO.

In accordance with the general organization of the locking, the relay 4L (see Fig. 5) is maintained dropped away until the approach locking relay I2AS associated with the signal I2 hasibeen picked up subsequent to the restoration of the signal I2 to stop. Because of the relay 4L'being dropped away, the relay 4BN is maintained picked up by its stick circuit (see Fig.l 2). Such stick circuit extends from (-1-), including back contact |29 `of relay 4L, front Contact |30 of relay 4BN, front contact I3| of relay 4BN, and winding of relay 4BN, to

After the lock relay 4L has been restored to its normally energized position, the stick circuit for the relay IBN is opened at back contact |23 (see Fig. 2) to cause that relay to be dropped away and thus complete the restoration of the parts of the system associated with the establishment of the route from signal I2 to signal I6.

To consider the mode of operation of the system in its restoration upon passage of a train, it will be assumed that a route is set up as heretofore described from signal I2 to signal I6, and that a train accepts the signal I2 and enters the track section lfI. The dropping away of the track relay 1TB. for the track section IT causes the dropping away of the relay IZN'R. to open front contact 46 (see Fig. 1) in the circuit for the relay MXR and thus cause the dropping away of that relay and the restoration in general of the route establishing means as has been described, except that the presence of the train in the track section 1T prevents the picking up of the relay 4L by opening its 'circuit at front contact |32 of relay lTR and therefore the stick circuit which has been described for the relay 4BN (see Fig. 2) is maintained closed to provide an interlock in the initiating circuit networks in the route establishing means to prevent the preconditioning of a route over the crossover 4.

With reference to Fig. 4, the presence of the train in the track section 'IT causes the dropping away of the relay 'ITR to providey a restoration circuit for the relay I2AS upon closing back contact |33, but the relay IZASO has no such restoration circuit and therefore can be restored only after a time interval. This is true because the immediate restoration of the relay IZASO is prevented by the opening of front contact |21 of relay I'I'R. The reason for this circuit arrangement is to provide that the overlap locking is eiective when a train occupies the portion of the trackway in the rear of signal I6 to provide that the overlap locking can be released only after the train has taken suficient time in the route from signal I2 to signal I6 to have necessarily reduced its speed suciently to be able to stop short of the signal I6. After such tirneinterval it is` safe to release the overlap locking of the track switches of the crossovers 5 and 6 to allow the operation of the track switches of those'crossovers as required to establish desired routes. Thus, after there was been sufcient time for the timing relay I2THO to operate and close its front contact |34, the relay IZASO is picked up, and the picking up of that relay allows the picking up of the overlap locking relay 5LO (assuming signal I I to be at stop). The relay 5LO is picked up under such conditions by the energization of a circuit extending from including front contact 40 of relay IIASO, front contact 4| of relay IZASO, front contact |35 of relay I IASO, and winding of relay 5LO, to Similarly, the relay -6LO is picked up upon `RWZ for the track switches of crossovers 5 and 6 as required in the establishment of routes, de-

' pendent of course upon the conventional switch locking relay 5-6L controlled by the track relays for the detector track sections and the approach locking relays associated with the interlocked group including the Crossovers 5 and 6.

With the overlap locking thus released, the operator can then proceed to establish routes as required, such as setting up a route for the passage of a train from signal I5 over the track switches of the crossover 5 to leave the lower of the two main tracks ahead of the train which has been assumed to be in approach of the signal I6.

To consider further the restoration of the apparatus associated with the setting up of the route from sig-nal I2 to signal I6, it will be assumed that a route is established to allow the clearing of signal I6 and thus provide that the eastbound train can proceed so as to allow the track section 'IT to become unoccupied and thus provide that the relay 4L (see Fig. 5) is picked up in accordance with the closure of front contact |32 of relay 'ITR. The picking up of relay 4L opens the stick circuit for the relay 4BN at back contact |29 and thereby allows that relay to be dropped away to complete the restoration to normal conditions of the parts of the system which have been employed in the route assumed to have been set up from signal I2 to signal I 6.

Precomtioning of routes-In accordance with' the general requirements of practice, it is provided that the track switches included in a route which is occupied by a train are locked in the positions corresponding to that route, and it is further provided that the operation of the route establishing means cannot be effected in a manner to call for an opposite position of any of those track switches, because of the possibility that the loss of shunt under a train for a detector track section could momentarily allow the picking up of a track relay which would allow the operation, or partial operation, of a track switch -under a train. The initiating circuit networks which have been more specifically considered heretofore when considering the establishment of routes are particularly provided in a manner to prevent the preconditioning of positions of the track switches when such track switches are included in established routes in View of the above described desirability for prevention preconditioning.

To consider a specific example in which the preconditioning of a route is prevented, it will be assumed that a route has been set up from signal I2 to signal -I6 and such route has been entered by a train as has been described. Under such conditions the relay 4BN is maintained picked up by its stick circuit. With reference to Fig. l, the pickingup of relay 4BN opens back contact 60 in the initiating circuit network for the establishment of routes for eastbound trains to prevent the conditioning of a route Vfrom signal II to signal I6 over the crossover 4 by opening the circuit which would be required to be closed in andere order that the exitrelay MXR could be responsive to the designation 'of the exit end of that route. Thus, it is provided that the route establishing networks will not condition a circuit to provide for the picking up of the relay dR when the relay lBN is energized, and therefore the track switches of the crossover d cannot be conditioned for operation to their reverse positions until the track switches of thatcrossover are unlocked and are free to be operated. A more complete description of the mode of operation for the prevention of preconditioning is found in the above mentioned patent to T. J. Judge.

To `consider now the conditions of locking of the track switches included in an overlapsection, it will be noted that conditions with respect to the preconditioning of routes are different in that the preconditioning of routes can be safely allowed involving track switches that are locked by overlap locking, but not included in routes that are set up. This is true 'because the conditions above described in which it would be possible to operate a track switch under a train are not involved in that the track switches under consideration are not included in routes that are set up and therefore the detector track sectionsv of such track switches are unoccupied by trains. It is therefore provided that the prevention of preconditioning is effective for the various routes that can be set up through the right-hand interlocked group of this embodiment of the present invention in a manner similar to that which has been speciiically described with respect to the preconditioning of routes in the left-hand interlocked group, but the overlap locking of the trackv switches of the crossovers and 6 is so provided that preconditioning of routes is allowed in the right-hand interlocked group, only if the track switches of the crossovers 5 and 6 are locked by reason of overlap locking rather than by reason of routes set up including such track switches within that interlocked group.

To consider a specific example of the allowable preconditioning described above, it will be assumed that a route has been set up from signal I2 to signal I6 requiring the power operation of the track switches of the crossover 5 to their normal positions and providing overlap locking for the track switches of that crossover. It will also be assumed that an operator desires to set" up a route for the passage of a train from signal I5 to signal 23 over the track switches of the crossover 5 in their reverse positions and thus proceeds to designate such route by the actuation lof the respective entranceand exit buttons ISNB in accordance with the picking up of the exitv relay I 4XR as shown in Fig. 2 rather than by the picking up of the relay EBN, as would be the case if the track switches were operated to their normal positions in accordance with the setting up of a route within that immediate interlocked group. Thus, although the track switches ofthe crossover are locked in their normal positions, the relay 5BN has not been picked up, and therefore there is no interlock in the initiating circuit network to prevent the picking up of the relay I SXR in response to the actuation of the exit button I8XB. In other words, although the track Switches of the crossover 5 are locked in their normal positions, there has beennothing accomplished in the control ofv those track switches to their normal positions for overlap to disturb the conditions of route establishment according to the general `principles of operation of the vroute establishing means as has been specifically described with respect to the establishment of routes through the left-hand interlocked group, and as has been specically described in the above mentioned patent to T. J. Judge for the setting up of the route under consideration extending from signal l5 to signal 23.

The conditions which have been described with respect to preconditioning of positions of the trailing overlap track switch 5BW are applicable also to the allowance of preconditioning of the track switches of the crossover 6 where the facing point switch BBW of that crossover is locked by `overlap locking. It will be readily apparent that the preconditioning of the track switches of the crossover 5 under such conditions can be readily accomplished because the overlap locking of such track switches is of no particular concern with the route establishing means provided for the selection of the position of such track switches in accordance with the establishment of routes within that interlocked group.

Indications-It is assumed that indications are provided on the miniature track diagram in accordance with the requirements of practiceto indicate the condition of occupancy of the respective track sections, the positions of the track switches, and the various routes established. Such conditions may be indicated by any suitable manner such, for example, as by indicator lamps disposed on the miniature diagram at points representative of the devices or route portion with which they are associated, or by providing a continuous line of light for the respective .routes established and track sections occupied by trains in a manner similar to that which is described in detail in the above mentioned patent to T. J. Judge. For the purpose of-simplication of the present disclosure these indications have not been disclosed as they can be readily provided by those skilled in the art in accordance with the requirements of practice.

With reference to Fig. 1, indicator lamps have been shown, however, disposed on the miniature track diagram at points comparable to the respective normal and reverse positions of the track switches of the respective crossovers 5 and 6 for the purpose of providing a distinctive indication when the track switches of the crossovers with which such lamps are associated are included in` routes designated for establishment but are locked by overlap locking of routes set up in the adjoining interlocked group. Thus the lamps EANE and 5BNE are provided for indicating the overlap locking of the track switches of the crossover 5 in their normal positions, and the lamp 5RE is provided for indicating the overlaplocking of the track switches of the crossover 5 in their reverse positions. Similarly, the lamps SANE and GBNE are associated with the indication of overlap locking of the track switches of crossover 5 in their normal positions, and the lamp GRE' is associated with the overlap locking of the track switches of the crossover 6 in their reverse positions. It is to be understood that these lamps can be provided on the miniature track diagram as illustrated, or they may be combined with other indicating means in accordance with the requirements of practice. For example, if the indications of the various established routes are provided by a continuous line of light, the indicator lamps `shown in this embodiment ofthe present invention may be combinedwith the lighting portions associated with the respective normal and reverse positions of the various track switches, the lamps shown in this disclosure being added to the complement of lamps provided in such an indication system, or the control circuits of the lamps of this disclosure being applied to the control of lamps already incorporated into the strip lighting system.

, With reference toFig. 6, control circuits are shown for the indicator lamps shown on the miniature track diagram of Fig. 1. These lamps are normally deenergized, and are energized only when the track switches of the crossover with which they are associated are locked by overlap locking and also are included in routes set up or designated for establishment. Although the lamps could provide a distinctive indication by steady energization when they are used as shown in this 'embodiment of the present invention, the lamps are shown to be energized by intermittently interrupted energy to cause them to ash for the purpose of calling attention to an operator of the indication as compared to other indications which may be provided as associated with the respective positions of the track switches.

To consider an example of the manner in which the overlap locking indications are provided, it will be assumed that the track switches of the crossover are locked in their normal positions by overlap locking and that an operator designates a route for establishment from signal I5 to signal 23, extending over the track switches of the crossover 5 in their reverse positions. Upon the picking up of the relay 5R in the establishment of that route, a circuit is closed for energizing the lamps 5ANE and 5BNE intermittently in accordance with the closure of back contact |31 of relay SLO. Such circuit extends from (FL-H, including front contact |38 of relay 5R, back contact |31 of relay 5LO, front contact |39 of relay 5NWP, and the lamps EANE and 5BNE, to It will be noted that the lamp SRE remains dark because of its circuit being open at front contact |40 of relay 5RWP, and therefore the iiasning of the indicator lamps 5ANE and EBNE indicates to an operator that the route exas selected by the positions of the track switches of the crossover 5 is dependent upon the closure of either front contact |41 of relay 5AN, front contact |42 of relay EBN, or front contact |38 of relay 5R as a means for applying energy to the circuit only when a route is established including one or both of the track switches of that crossover.

v It is believed to be readily apparent with reference to the circuits shown for the energization of the indicator lamps GANE, EBNE and SRE for the crossover 6 that such lamps are controlled in a manner corresponding to that which has been specifically described with respect to the control of the lamps associated with the crossover 5.

4Having described one embodiment of the present invention as applied to the control of track switches and signals for a particular track layout as one embodiment of the present invention, it is desired to be understood that this form is selected to facilitate in the disclosure of the invention rather than to limit the number of forms the invention may assume, and it is to be further understood that various alterations, adaptations and modifications may be applied to the specific form shown to meet the requirements of practice without in any manner departing from the spirit or scope of the present invention except as limited by the appending claims.

What I claim is:

1. In a switch and signal control system of the character described for a track layout providing by adjoining interlocked groups first and second adjoining routes respectively, each of such routes having a signal for governing entrance to that route for a given direction of traffic, and said second route having a trailing track switch for given direction of traiic, manually operable means for designation of the respective entrance and exit ends of each of said routes, an exit relay for the exit end of said rst route, route initiating means responsive to the designation of the entrance end of said first route for conditioning said exit relay for that route so that it can be picked up in response to the designation of the corresponding exit end only if the route is available extending between the respective entrance and exit ends thus designated, said route initiating means being eiective to pick up said exit relay in response to exit designation only if said trailing switch in said second route is free to be `operated to its normal position, route establishing means responsive to the picking up of said exit relay for said first route for selecting the positions required for the respective track switches to align a route between the designated entrance and exit ends, means responsive to the picking up of said exit relay for causing the power operation of said trailing switch in said second route to its normal position, and means for clearing said signal governing entrance to said first route only if said trailing switch of said second route is operated to its normal position.

' 2. In a switch and signal control system of the entrance-exit type for a track layout having a signal governing entrance to a first interlocked group and having a second adjoining interlocked group including a facing point switch with respect to said signal for selecting one overlap track section to be included in the control of said signal when in its normal position and another overlap track section to be included in the control of said signal when in its reverse position, route establishing means for each of said interlocked groups for automatically selecting the positions of the respective track switches required to set up any desired route in response to the manual designation of the entrance and exit ends of that route, switch operating means for positioning each track switch in accordance with the position selected for that track switch by said route establishing means, and overlap locking means for allowing the operation of said facing point switch when said signal is clear if each of said overlap track sections is unoccupied by a train, but said overlap locking means being effective to prevent the operation of said facing point switch when said signal is clear if said overlap track section selected by the opposite position of said facing point switch is occupied by a train.

; 3. In a switch and signal control system of the character" d-escrib'ed for a, trackl layout havin'g a signal governing entrancel to a rstinterlocked group including power'track switches and having a second adjoining interlock-ed group including a facing point power operated switch withv respect to said signal for selecting one overlap trackV Vsection to be included inthe control ofYA said signal when in its normal position and another overlap track sectionA to. be included. in the control of said signal when in its reverse position, overlap locking means for said facing pointV switch'for preventing the power operation or that: switch when said signal is clear if said overlap track section selected by the opposite positionof that track switch from its last operated position isv occupied by a train, manually operablecontact means for the respective entrance and exit ends of each of the routes in each interlocked group for the designation of the ends of routes to be established, and route establishing means for each of the interlocked groups for selecting the positions of the respective track switches required to set up each route in response to the manual designation of the entrance and exit ends of that route, such means being effective only if each track switch required to set up that route is free to be operated to its required position except that said route establishing means is eiective for a route in said second interlocked group requiring the power operation of said facing point switch even though the power operation of that switch is prevented by said overlap locking means, whereby the preconditioning of a track switch is allowed only when that track switch is locked by said overlap locking means.

4. In a switch and signal control system, the combination with a track layout having a signal governing entrance to a first interlocked group and having a second adjoining interlocked group including an overlap track switch with respect to said signal, of a time element device initiated by the restoration of said sign-al to stop upon the acceptance of that signal by a train, route establishing means responsive to the manual designation of the respective entrance and exit ends of each route in each interlocked group for selecting the positions of the track switches required to establish that route, switch operating means for causing the power operation of each trackl switch in correspondence with the position selected by said route establishing means, and overlap locking means eiective to prevent the power operation of said overlap track switch in said second interlocked group when said signal governing entrance to said first interlocked group is clear, irrespective of whether or not said overlap track switch is included in an established route in said second interlocked group, said overlap locking means being effective subsequent to the restoration of said signal by the passage of a trainfor a predetermined time interval as measured by said time element device.

5. In a switch and signal control system for a track layout having a signal governing entrance to a rst interlocked group and having a second adjoining interlocked group including an overlap track switch with respect to said signal, overlap locking means for preventing the power operation of said overlap track switch when said signal is clear, said overlap locking means being effective upon the restoration of said signal toiA stop for a predetermined time interval subsequent to such restoration, route establishing means responsive to the manual designation of the respective entrance and exit ends of each route in;` said "and sai'd second interlocked groups for selecting thepositionsof the track switches requir'edto-'establish that route, said route establishing means'for said second interlocked group being effective to select positions of' said overlap 'track switch irrespective of the eiiectiveness of said overlap locking means, switch operating means forcausing the power operation of said overlapl track switch in accordance with the position selected for that track switch by said routeV establishingV means; said switch operating means being 'effec-'tive subject to limitation by said overlap locking means.

6. In a switch and signal control system of 4theentrance-exit'type fora track layout having a signal-governing entrance to one interlocked groupv with its control dependent upon an overlap trackse'ction includingfa trackV switch in a second interlocked group, overlap locking means for locking said track switch when said signal is clear, route establishing means responsive to the manual designation of the respective entrance and exit ends of each route in said one and said second interlocked groups for selecting the position of each track switch required to set up that route, and indication means for providing a distinctive indication on a control panel when said track switch is contemporaneously locked by said overlap locking means and is selected to be included in an establishd route by said route establishing means.

7. In a switch and signal control system of the character described, the combination with a track layout having a signal governing entrance to one interlocked group and its control dependent upon a selection by a track switch in a second interlocked group, of overlap locking means for locking said track switch in said second interlocked group when said signal is clear, route establishing means effective in response to the manual designation of the respective entrance and exit ends of each route in said one and said second interlocked groups for selecting the position of each track switch required to set up that route, an indicator lamp for said track switch, and means for intermittently energizing said indicator lamp when that track switch is locked by said overlap locking means provided that said track switch is selected as being included in an established route by said route establishing means.

8. In a switch and signal control system for railroads for a track layout having a signal governing entrance to one inerlocked group with its control dependent upon a track circuit selection provided by a track switch in a second interlocked group, overlap locking means for locking said track switch when said signal is clear, route establishing means responsive to manual designation of the respective entrance and exit ends of each route in said one and said second groups for selecting the position of each track switch required for the establishment of a route extending between the manually designated entrance and exit points, indicationmeans for distinctively indicating on a control panel the normal or reverse position in which said track switch is locked by said overlap locking means at a time when a route is selected by said route establishing means requiring that track switch tor be in either its normal or reverse position.

9. In a switch and signal control system of the entrance-exit type, the combination with a track layout having a signal governing entrance 27 to one interlocked group and having its control dependent upon a selection by a track switch in a second inter-locked group, of overlap locking means for locking said` track switch when said signal is clear, route establishing means eiective in response to the manual designation of the respective entrance and exit ends of each route in said one and said second interlocked groups for selecting the position of each track switch required for the setting up of that route, indicator lamps for the respective normal and reverse positions Vof said track switch, means for energizing said indicator lamp associated with the normal position of said track switch when that track switch is locked by said overlap locking means in its normal position and said route establishing means is eiective to select a position required for that track switch in an established route, and means for energizing said indicator lamp associated with the reverse posi- .tion of said track switch when that track switch REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,298,946 Judge Oct. 13, 1942- 2,425,109 McCann Aug. 5, 1947

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