US2355327A - Centralized traffic controlling system for railroads - Google Patents

Description

Aug. 8, 1944. 2,355,327

CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS R. M. PHINNEY ET AL e Sheets-Shee 1 Filed March 1, 1943 INVENTORS RP l Phgia 22d GWDavison THEITZ ATTOR Y I Aug. 8, 1944., R. M. PHINNEY ET AL CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Filed March 1, 1943 6 Sheets-Sheet 3 Inn 36 r65 E0 I $35 INVENTORS RMPhmney and GWDawson THEIR ATTORNEY flu cos. Eo f cosEo n Aug. 8, 1944; R. M. PHINNEY ETAL 2,355,327

CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Fil edMarch 1, 1943 6 Sheets-Sheet 4 vison! BY 'THEIR'ATTORNEY INVENTOR5 RMPhinne and GWDa' coE E Q AugI8, 1944. R. M. PHlNNEY ET AL 2,355,327

CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Filed March 1, 1943 6 Sheets-Sheet 5- PIC-11.2.

INVENTOR5 v P. M ghw ZZdfiD/ZQEOR THE-IR ATI'ORNEY Aug. 8, 1944. 2,355,327

I CENTRALIZEDTRAFFIC CONTROLLING SYSTEM FOR RAILROADS R. M. PHINNEY' ETAL e Shee t s-Sheet 6 Filed March 1, 1943 PMPh cT GWD mney an avlson WMMM, THEIR ATTORNEY oui oLPcoD indicate the respective positive and negative ter minals of suitable batteries or other sources of direct current, and the circuits with which those symbols are used always have current flowing in the same direction. The symbols (3+) and (B-) indicate connections to the opposite ter minals of a suitable battery or other direct current source which has a central or intermediate tap (C). The intermediate tap (C) of such source.

corresponding field location. Each of the relays Z is normally deenergized, and is energized with a particular polarity for the clearing of signals for governing trafiic to the right, and with the opposite [polarity for the clearing of signals governing traffic to the left.

At each of the field locations there is a stop repeater relay'M for each of the entering signals, and there is-a relay M for the leaving signals (see Fig. 2). There is also a yellow-green repeater relay at each of the field locations for I each direction of trafiic.

of energy is connected at each location to a common line wire designated as H common.

This embodiment of the present invention is applied to the governing of trafiic from a control ofiice through a track layout comprising stretches of single track spaced by: stretches of double track which can be used for-the meeting of trains. Although only a short and simple track layout has been chosen for this'embodiment of the present invention, it is to b understood that the invention is applicable to practically any track layout of a similar general nature to be encountered in practice. It is'believed that it will be readily apparent as the description of the invention progresses that the system as herein dis closed is of such a nature that by using this as a typical embodiment," those skilled in the art can readily adapt'the system to :most track layouts to be encountered in 'practicein connection with centralized trafiic control.

The track switchesemployed at the' ends of I has associated therewith a switch circuit controller SCC which has contacts used for circuit selection at the particular location of such track switch, and each of the track switches is provided with manually operable means for operating the track switch in order to make movements possibleagainst the normal direction of trafiic.

The signals employed in this embodiment of the present invention are of the searchlight type;

indicative of the particular type of signals em-' A neutral polar relay Z is provided at each of the field locations for controlling the signals in accordance with the manual actuation of the signal control lever at the control Office 01. t e

A neutral relay JS is provided at each end of each stretch of double track, together with a fpush-button PB for use in connection with the movement of trains against the normal direction A neutral relay TS is provided at each of the field locations, and it is used in the communication of track indications to the control office. It is also used in connection with the provision of stick signal control. used in connection with the provision of what is commonly known in practice as a galloping circuit for the communication of OS indications to the control office, the use of such relay making it possible to transmit the OS indications for theopposite ends of a stretch of double track to the control ofiice over a single line circuit. Slow act-' ingneutral indication relays TK are provided at the control office for the various 0 S sections for causing the illumination of the various indication lamps TE, and associated with such relays is a bell BK which is momentarily sounded upon the picking up of any track indication relay TK.

The line circuits in the field comprise line wires ZW common, l-ZZW, 34ZW and 2-3TKW extending from the control ofiice to location No. 2; line wires ZW common, 3-4ZW, H common, 24, 15,125, I26, 98 and 3'I'KW extending between location No. 2 and location No. 3; and line wires ZW common, 3-4ZWI, H common, 42 and extending between location No. 3 and location No. 4.

Having thus considered the general organization of the system, consideration will now be given to itsmode of operation.

Operation The conditions of the system that exist when the trackway is unoccupied and the signal control levers at the control ofiice are in their stop positions. are hereinafter referred to as the normal conditions of the system. Under such conditions the leaving signals at the various field locations are at stop in accordance with the position of their respective signal control levers at the control Office. The entering signal at each of the field locations for governing the normal direction of traffic through the stretch of double track in advance thereof, however, is normally at caution because the next signal in advance, which is usually the leaving signal for the opposite end of the stretch of double track, is normally at stop. The lower arm of each of the entering signals is normally at stop because it is used only for governing movements against the normal direction of trafiic in the stretch of dou-- ble'track. In accordance with the normal position of the signal control lever SGL as illustrated in Fig. 1A, the line controlled relays Z for the various field locations are normally deenergized. The automatic intermediate signals such as signals 4-3 and 3-4 (see Fig, ID) are normall clear because the next signal in advance thereof,

A flashing relay FL is' aaaa'azrr.

which is an entering signal in each case, is; at caution. The intermediate searchlight signals employed areenergized directly over polarizedline circuits having their polarities selected by yellow-green repeater relays YGP in a manner wellknown to those familiar with the art. a

To consider the mode of operation upon passage of a train, it will be assumed that an eastbound train is in approach of the entering signal 2A (see Fig. 1B). Inasmuch asit is to be assumed that the trackway in advance of the train is unoccupied, the signal 2A is. at caution for governingv passage of the train over the lower track of the stretch of double trackathroughthe track section 2 3T to the leaving signal 30 at the right-hand end of such track section. The signal IA has its windin-g'energized under such conditionslwith a polarity 'to causeit to display ayellow indication by the closure of acircuit extending from (B), including back contact 20 of relay 3CYGP (see Fig. 1C), front contact 2| of relay? 313M, normally closed contact 22 of the thermal relay 3TH, winding of the approach lighting relay 3BR, normally closed contact 23 of the switch circuit controller 3SCC,'line wire 24. front contact 25 of relay 23'I'R.'back contact 26 of relay 2Z, normally closed contact 21 of t e switch circuit controller 280C, front. contact 28 of relay 2TR,;winding of signal 2A, front contact 29Jof relay 23M, and front contact 30 of relay 2C2DM, to. (C). Ifin the circuit ,iust described; :the relay 2Z is picked up with its polar contacts. operated to right-hand positions be cause of the actuation of the signal control lever |2SGL atthe control oflice to its right-hand position, the circuit just described. will include polarcontact 3| of relay ZZfin. its right-hand position rather than the hack contact 26 as employedwhen the relay 22 is .deenergized.

If the route were established .farther in ad-# vanceof the train so as'to cause the signal 36 to indicate proceed; the relay 3CYGP would have been picked up, and the shifting of contact 20 would have beeneffective to cause the signal 2A tovindicate clear'by the energization of'its cir cuit with the opposite polarity fromthatwhich has been described for causing that signalyto indicate. caution. The circuit for the control of relay= 3CYGP is not shown-but: it corresponds to the circuit shown in Fig. 2 for the energization of a relay: ZCYGP. Relay .ZCYGP is energized when signal 2Cis clearedby an obvious circuit closed at contact 60 in its right-.hand'position, and it is energized when signal 2C is .at caution by a circuitextending from including contact Ell ot 3 signal 2C in its vertical position; contact 61 of signal 20 in its left handlposition and' winding of relay ZCYGP, to

The passage of the train pastthe signal-2A causes the dropping away of the track relay 2TB for the 'OS track sectionZT, and the dropping away of' such relay causes the signal 2A to display a stop indication by placing a shunt on the winding of the signal in an obvious manner upon the closure of back. contact -28; The opening of front contact 28'causes the. dropping away of the approach lighting relay.3ER for the leaving sig nal 36 .(see Fig. 10) at the right-hand. end of the stretch of double track: The closure ofa back contactof' the relay 313Rw is effective to ca'u'se the 1 display of a signal indicationup'on theillumination of the lamp in the signal 3C and also the lamp of the signal 3D, in a' manner correspondingto that shown inFig. '2 for the illumination of thelamps of the signals-2C and 2D inaccord ance'with. thelclosure of back contact 32 offithe relay 211R, which-.has a circuit similar to that described for the! relay 3E3. It .will .be noted that the inclusion of frontcontact' 25 of relay 2.

3TB. in the; circuit for signal'ZA, and in the cir-- cuit for re1ay3ER provides that the conditions of'those devices will remainas they have been described after the detector track section 2T hasgbecome unoccupied in the rear of the train, as long as the train occupies the track section- 2-3T. Inasmuch as signal 2A is an automatic signal it will be restored to caution when the track section 2-.-3T becomes unoccupied in; the rear of the eastbound train by' the energization of a circuit which has. been described when considering the normal conditions. of thesystem.

Should it be-desirable for the operator at the control office to hold the train at the leaving signal 3C, he-can do so by failing to actuatethe signal control lever 3.-4SGL for theclearing of that leaving signal. It will be noted at this point that the making of the :entering signal 4A (see Fig. 1D) an automatic signal, provides a. means by which the operator canhave distinctive control over the leaving, signal 3C at location No. 3 (see Fig. 1C) without affecting signalJA'. "That is, if a first train were inapproach of the entering signal 4A, and it weredesirable to hold a following train at the leaving signal 3C,.it would be possible to do that because the. signal control lever 3--ASGL would not be required to be actuated to its right-hand position for the clearing of the entering signal lA. for the first train. In this manner distinctive control is provided for each of the leaving signals, without afi'ecting the entering signal at the opposite end of the stretch of single track involved.

To consider further progress of a train along the stretch of single track.

The actuation of the lever 3-4SGL '(see Fig. 1A) to its right-hand position causes the picking up of the relays 32 and 4Z atthe respective field locations 3 and 4. The line circuit. closed for the energization of such relays extends from the positive terminal of the control office line battery LB including. contact 33 of the signal control lever 34SGL in its right-hand positionyline wire. 3-4ZW, winding of relay 3Z (see Fig. '10). line. wire 3--4ZW I. winding of relay 4Z1 (see Fig. 1D), and common linewire ZW, to'the center tap of the line battery LB (see Fig. 1A);

The picking up of relay 3Z at the right-hand end of the stretch of double track, under such conditions ofenergization, causes the polar contacts of such relay tobe actuated to their righthand positions, and the signal 3A is put to stop because of the-opening of a, circuit for such relay at contacts 34. and .35 of relay3Z. After the s gnal 3A has been put to stop, the stop repeater relay 3AM is picked. upby the energization of a circuit not shownbut corresponding to the typical circuit shown. in Fig. 2 for the energization ,of

the relay 2AM.-. The..circuit for relay: 2AM ext tends from including contact 36. of signal 2A and contact 31 of that signal closed in the position assumed when. the winding: 38 of the signal is deenergized, and winding of the relay contact 40 f relay 4-3S; front contact" 41' of relay4-3TR line wire 42, front contact 43 of relay 4-3TR), front contact 44 of relay 3Z, polar contact 45 ofrelay 32 in' its right-hand position, fron't contact'46 of relay 3T8, normally closed contact41 of the switch circuit controller 3SCC, frontc'ontact' 48 of'relay 3AM, front contact 49 of relay 3BM, back contact 50 of relay '3JS, and winding of signal 30, to (C). The energization of s'ignal'SC under such conditions causes that signal to display a green indication because of the polarity appliedtd the circuit by the yellowgreen repeater relay 3-4YGP at the intermediate automatic signal location in advance. If relay 3-4YGP were' dropped away because of the presence of 'an eastbound train in its block, the polarity'applied by contact 39 to the circuit for signal 3C would be such as to cause signal to display a caution indication. v

It will be noted that the energization of the circuit for causing the signal 30 to indicate caution is dependent upon the stick relay 3-48 at the intermediate signal location. Such stick relay is of the type normally employedin absolutepermissive-block signalling systems, and it is picked up only upon thepassage'of an eastbound train. Thus, the condition whereby signal 3Q can be'energized with a polarity to cause that signal to display a caution indication is dependent upon the occupancy'of the block in' advance of signal 3-4 by an eastbound'train. Under such condi tions, the signal 30 can beenergized, if the operator in the control oflice operates his signal control lever 3-4SGL to its right-hand position, by

a circuit extending from (B-), including front contact 59 of relay 3-4S (s'ee'Fig. 1D), back contact 39 of relay 3-4YGP, back contact of relay 3-4S, front contact 4| of relay 3-4TR wire 42, front contact 43 of relay 4-3TR (see Fig. 1C), front contact 44 of relay 3Z, polar contact 45 of relay 3Z in its right-hand position, front contact 46 of relay 3TS,'contact 41 of switch circuit controller 3SCCQfrorlt contact 48 of relay 3AM, front contact 49 of relay 3BM, back contact 50 of relay 3JS, and winding of signal 30, to (C) Upon the acceptance of signal BC by an eastbound train, the dropping away of relay 3TB for the detector track section 3T causes a tumbledown through the stretch of single track between locations 3 and 4 according to usual practice in APB systems. That is, the dropping away of: relay 3TB opens the circuit by which the signal 4-3 is normally energized to cause such signal to beconditioned for the display of a danger indication. The dropping awayjof the relay 3TB. opens the circuit for signal 4-3 at front contact 6|, the circuit being normally energized from (B-I- including front contact 62 of relay 3AYGP (see Fig. 1C) front contact 6| of relay 3TR, front contact 63 of relay 3C-3DM, front contact 64 of relay 4-3TR, wire 65, front contactBB of. relay 4-3TR and winding of signal 4-3, to (C) I The deenergization of signal 4-3 is effective to cause the dropping away of its yellow-green repeater relay 4-3YGP in the usual manner, and the dropping away of that relay is efiective, by theopening of front contact 61, to remove energy from the circuit forthe'control of signals 40 and 4D to prevent the clearing of either of such -sig-- nals if an operator at the control 'oflice should inadvertently actuate, the signal, control lever 3-4SGLto its left-hand position at a time when an eastbound train is 'occupying the stretch of contact "39 of relay 3-4YGP (see Fig. 1D) ,loa'ckv single track between locations 3 and 4; Although the circuits have not been shown in detail for the control of signals 4C-and 4D, it is to be understood that such signals are controlled in a manner comparable to that which has been described forthe control of the opposingsignal 36 at location deenergizes and applies a shunt to the winding of signal 30 to cause that signal to be ut to stop. Signal '30 will be maintained at stop until the relay 3TS is again picked up; and, as a means for providing stick signal control, the relay (ITS v cannot be picked up after the track section 3T for signal 30 at front contact 44 to cause that signal to be maintained at stop after the relay 3TS is restored to its normally energized position.

Assuming the operator at'the control office to-have restored the lever 3-4SGL to its center position after receivingan indication that the eastbound train'has entered the OS track section 3T, the dropping away ofthe relay 32 is effective to close a circuit by which the relay 3TS can be picked up when the detector track section 3T becomes unoccupied. Such circuit extends from (B+), including front contact 68 of relay 3TB, winding of relay 3TS, and back contact 69 of relay 3Z, to (C). The picking up of that relay closes a stick circuit at front contact 10 to shunt back contact 69 out of the circuit just described, thereby providing that the relay 3TS will be maintained picked up subsequent to the pickingup of the relay 32 when the operator at the'control ofiice next actuates the signal control lever 3-4SGL to a signal clearing position. Upon consideration of the circuit that has been described for the signal 30, it will be noted that such signal can be caused to indicate caution for the passage of a following train, only after the first train has vacated the respective track sections included in the block in advance of that signal.

Inasmuch as the track switch 3W is a spring switch, it is not necessary for the eastbound train to. stop at the switch. If the switch has a facing point lock such as is disclosed in the above mentioned application of O. S. Field, Ser. No.

368,034; filed November 30, 1940, the switch is mechanically unlocked by the springing of the rails as the train proceeds through the trailing switch;

The entrance of the eastbound train into the track section 4-3T is efiective to cause the approach lighting of signal 3-4 by the closure of an obvious circuit at back contact H for the lamp of such signal. Although the complete circuit for the signal 3-4 is not shown, inasmuch as the present system is symmetrical for both directions of train operation, it is to be understood that such circuit is comparable to the circuit which has been described for the energization of the intermediate signal 4-3 which is,

used in governing the opposite direction of traff ce. The approach of the eastbound train to signals 4A and 43 completes the consideration of ,the passage of a train through a typical portion of the trackway. for which Lthesystem is provided. Thatis, the control of signals-AA and 4B is comparable to the control of signals. ;2A and 2B which are specifically considered as typical of entering ,signals provided at .Yafious other locations in the track layout.

.Mofvements against the normaldirection of ,trafiic.?There are'certain conditions encounteredin practice. requiring movements against the normal direction of traffic in a sectioniof double track. Such conditions can .be, ,for example, when one train is to pass another train proceeding in the same direction, or :when a worktrain is to get into the clear to allow the passage ofa train in one direction or another. The passingof trains proceeding, in thesame direction can be accomplished in either of two ways. The first train ;to approach the .double track stretch can enter in the normal direction of traific, and the followingtrain can pass. against the: normal. direction of trafiic; or, the first train can enter against thenormal direction of .traffic and the .second train can pass in the vnormaldirection of trafiic. The system provides means by which an operator at .the controloflicencan have .control over train movementsto govern the passing of trains in either of. these two ways. Assuming thata first eastbound trainhas proceeded in the normal directionof traffic solas to occupy the track section 2-3)? in a manner which has been described, thesignaliA isv at sto .because of the opening of its circuit at front contact of the track relay 2..-3TR, and the. second train in approaching signal-2A will berequiredto stop at such signal. Undersuch conditions the procedure is for a trainman to .call the operator :byuselof. a telephone .at location No.2 andreceive instructions as to whether the second train. should proceed-againstthe normal direction of traffic inthe double .trackiseotion or it should wait'and follow the first train. If the trainman is instructed to reverse the track switch 2W, and proceed against the normal direction ofatraffic, he proceeds to operate the track switch by-handx to its reversed-position, and such operation is effective by the. opening'iof contact 12 of switch circuit controller 230C in the circuit for relay 2 2BR and I signal 1 3A at location No. 3 to cause that signal to be put .to stop, and .to. cause the relay 2ERto be dropped away toprovide for the illumination of the lamps of signalswEC :and:2Dvat location- N0. 2.

The deenergization of signal 3A isaefiective to cause the picking up of its stop repeaterirelay 3AM, and the picking up of thatrelayzis efiective to cause the energization of therelay12BH at location No. 2. The relay ZBH is energized by-a circuit extending from (B+) including front contact 13 of relay 3AM. (see Fig. 10) front contact 14. of relay3-2TR, wire 15, contact176 of switch circuit controlleriSCCAsee Figl-B) closed inits reverse position, and winding of. relayriZBH, to (C). Upon the picking up of .the-relays.-2BH,.a

circuit is closed :for the winding of thethermal relay 2TH extendingnfrom (B+), includingzfront contact :11. of relayZTS; front contact 18 of relay 2AM, front contact '19 ofrelay ZBH, .windingof thermal relay 2TH, and:front contact'80 of. relay ZBM, to (C). Itwill be readilyapparent that the heating of the'thermal relay ZTHcan become efiective only if :the 1 track section 3--2T is unoccupied by a; train and only if the opposing signal 3A is atstop; and notonly must thesecon ditions be fulfilled before-the signalzzB can-irrdie te .r peee -.Qhut.-th si na .2 can indi a n eeeeaenly e e thema lre y Z ha h d tim to pne a e-ifiq htime i y d d in ord th t. an pe train w ich ma ha e be approaching the signal QAat the time it was put t te awquldheveh d' time to h bro h t a stopin therear f signaltA, or ,havehad time to yermneueh ah ea the ch p in away of herel :1?i R.;t peh e i u t for r 33H at .irent;.eentaet -14- f f s the win in o ne to operate, if the line continued to be energized. the wi n o ie eHB ner ized .llhde j. heend t s extends from (B+) including nt contact H of relay .ZTAS, re teehtaet 4189i .tel r JAMI QM Contact 19 9 relay,-2B;H, I, contact 8 of thermal relay 2TH, i d est ei and. om. e e 8 of Br l -2 M. 1? The en e t h of signal 13 causes the eawa ef e e r p a Q W-tZPMfQ si na by t e ope i of its circuit atcontact 8 see Fig, 2), and the dropping away ofsuch rel by theclosure of back confl we a t?! o thermal a 2TH 9 1 h ther ire it iuehdeseribed for h er z eh eft e wih li eefl iehel 2 It w l no thatt -wehn ne 'ewe 'ef e a ZB causes the eee iheef thetherh e .rel rZTH- mpemng h ir i e thewhdi e iih t e a t 0 tactBB. 1 r r When l h .eeetbehhd t ain e ee t the 5 5 213 the q ping as: 0f t e tr re ay 2TH el ee he-fireme awa 9 e fl by op in the w e a. 91 119911 3 1 9 T e t e eireu t'b 1w. 'ehth re a Sis n ma e gized extends frorn includin g front contae flef re a .ns n of relay 6 a front 991 2 9. 9 em-2T5 t (CL The el ZTS, byiheincl-us of back contact 92 of -relay ZZ in itsp rcuit, is efiective to provide eh-ei ha .eeni ie eiena 2 in a nn m a ;th iheh e es hed 1 W nection w hthe trol of signal 30.

ht erfi he-ltre t eishee th h w t ,2W, s uch-;tracl:, h is -restored to its norm l. ee tie erelega h es hed e eb the i nal. 2A ee -cle re d dependent upon the signal. i a ma ner which hesheen eserihed- :Te teehs der; u io r e 1-, of th rai v on of traific, it willbe I M de red tohave such train PIQQ BQQP J of; $m b location N B' Qati0n ;NQ. (i. -Before signal P een a e hhtq l d. t d spl e proceed .qieeti for he pass'age of thetrainagainst the heme e ie -e tre iwt e hime m eommunieet h ie epheh wi the Ope the control ofiice and receive instructions with tes ec tot h rt zehi; ncreme the eher de irestoe Q hem sweet h rai i the stretchof sin le. track: be we l cat n .N 3 .andvlocation No.;4 .h i st u ra n to depress the push-button 3133 which located .along; withitheitelephone at location No. 3; and the operator'atithelcontrol. of ce must actuatethe .signaLcontrol .ilever 3,- 4SGL from its centerto. its right.-;hand,=position, at a time when the .trainman ..is .rholdi-ng. thelpushzbutton :QPB at location :No. .3 in its.:.depressed posi y this. arrangement; .the. movement against the normal direction..of.; trafiic.into the stretch of a hmm he the w q ih h of any misunderstanding. 1

single track between the location No. 3 and-the location No. 4 can-be made=only-upon-the cooporation-of the trainman and the operator at the control ofiice, thus eliminating the possibility The depression of the button 3PB; when the relay SZ is dropped away-,- cau'ses' the picking up of therelay 3J5 for Selecting between signals 3C and 3D. The-relay -3JS is picked up under such conditions by the energization of a circuit extending from :(B-F) including contact 93 of button 3PB- in its depressed position, upper winding of relay -3JS, and back: contact 94 of relay 3Z, to (C). When the operator at the control ofiioe actuates the signal control lever 3-4SGL to its'right-hand position, while the relay 3JS'is maintained picked up because of the closure of contact 93 of push-button3BB, the

picking up of relay 3Z opens'thepick-upcirrelay 3JS, and front contact 94 of relay 3Z,'-to

(C). It will be noted that the inclusion of'iront contact 95 of relay 3TB in that circuit rovides that the. relay 3J3 can be dropped away upon entrance of a train into the track Section 31?, and the inclusion of front contact 94 of "relay 3Z in that circuit provides that the operator at the control ofiice can cause the dropping away of relay 3J8 by restoring the signal control-lever 3-43SGL to its centerpositionz" I With the relay 3J S picked upj-andassuming the stretch of track betweendoc'ation No 3 and location N0. 4 to be unoccupied,'a circuit is closed to cause the signal 3D to indicate caution. Such circuit extends from (B+) including'front contact 39 of relay 3 -4YGP, back contact 40 of re-- lay 4-3S, frontcontact 4 Inf-relay 4-3'IRE, wire 52, front contact 43 of -relay 4 3TR,"front contact 44 of relay 3Z, polar-contact 45-of re'laytZ in its right-hand position, front-contact Mi'of relay 'STS, contact 41' of'switch circuit controller 3SCC, front contact 48 ofrelay"-3AM,- frontcontact 49 of relay 33M, frontcontact '50 of relay 3J S, and winding of signal 3D, to (C); Upon the acceptance of signal 3D by the train; the dropping away of relay 3TB is effective to cause the" dropping away of relay BJS in-a mannerwhich has been described. The dropping away of relay 3T8, because of the opening of itsci-rcuit' at front contact 63 of relay 3TB, applies 'a'shunt'to the wind ing of signal 30 to cause such'sigiial-to indicate stop. The signal 3D is caused to' indicate stop by the opening of its-circuit at front contact 50 of relaySJS. 1

In order to facilitate the movement'of trains, it is provided that the leaving signal governing a movement against the normal direction of traffic, such as the signal 3D, can be caused to clear by the actuation of the-push-buttonPB at the opposite end of the stretch of doubletrack when a trainman receives instructions at that point to enter such stretch against the normal direction of traffic. That is, for-example, to considerthe specific condition that hasbeen described, at the time the trainman .calledthe operator at location No. 2 to receive permission toreverse thetrack switch 2W and proceed against .themormal di-' rection of traiiic, he could have depressed the p'ush-button'ZPB (see Fig. 1B), and, by the op erators-cooperation in the actuation of the signal control-lever 34SGL from its center to its righthand position when the button ZPB was de pressed, cause the picking up of the relay 3JS (see Fig. 1C), and the subsequent control of the signal 3D to indicate caution. By this procedure, the train would not-be required to stop at location No. 3 because the signal 3D would be conditioned.

for passage of the train, without requiring the actuation of the push-button 3PB. The relay 3J3 could be picked up under such conditions-by the energization of a pick-up circuit extending from (B+), including contact 91 of push-button ZPB (see Fig. 1B) in its depressedposition, line wire 93, upper winding of relay 3JS. (see Fig. 1C), and back contact 94 of relay. 32, to (C). It will be readily apparent that .the picking up of relay 3J8 in this manner would be effective to causev the venergization of circuits which have been described by which the signal 3D can be energized so as to indicate caution.

It will be noted that although each of the entering signals is automatic and thus is normally at caution, such signal .can be put to stop at the will of an operator if he wishes to stop a train at that signal. He can do this by operating the controllever belonging to that signal to a position for clearing the. opposing signal. For example, signal 2A can be put to stop by the actuation of the lever. I-ZSGL to its left-hand position. By such'operation the relays I2 and 2Z are energized with a polarity to operate their polar contacts to their left-hand positions thus opening the circuit for signal 2A'at back contact 26 and polar contact 3| (see Fig. 1B)to cause signal 2A to indicate danger. The lamp in signal 2A is illuminated upon the approach of a train by the closure of back contact. I23 of relay |-2TR (see Fig. 2). The circuit by which the relays I Z and ZZ'are energized under such conditions extends from the negative terminal of line battery LB .(see Fig. 1A) includingcontact I24 of lever l2SGL in its left-hand position, winding'of relay [2, line wire .I-.2ZW, winding of relay 22, and common wire ZW to the center terminal .of line battery LB. It is believed to be apparent from the mode of operation as it has been described for certain; typical train "movements for a particular direction of traific thatla similar modelof oper? ation is efiected under similar. trafl'ic conditions for, the opposite direction of trafiic, as the. system is symmetrical in the -.provision;of appara-. tus and in its .circuit organization for both .Zdi' rectionsfof trafiic. It will therefore be readily understood that themeeting of trains j canqbe accomplished with the trains proceeding in; the normaldirections of traffic through the double trackportions of the track layout with a, mini-'- mum amount of delay, itbeing;entirelypossible to provide train meets in somev cases without either train being required to stop. 1. r

Indications-In order that an op'eratorj..may be informed of the passage ofla train" through each of the detector track sectionSgth-zoccupancy of each .of such sections 'is. indicated 'by the illumination of a corresponding-indicator lamp TE on the trackv diagram alt-the. control office. Although various meansforitransmitting the indications from the respective field loca: tions to the control ofiice can beemployedgingthe embodiment of the. present :invention. shown; in Figs. 1A through 1D, the indicationsare grouped in pairs and transmittedover a single line circuit for each group, one indication line wire being used in combination with the control common wire ZW for each group.

As a typical example of how indications are 1 communicated from a pairof field locations to the control office, the circuits'have been shown in detail for indicating the occupancy of the-detector track sections at field location No. 2 and at I field location No. 3, such indications being trans-- mitted over line wire 2--3TKW.extendingfromthe control office to field location No.- 2.

To consider specifically the manner in which the indications are transmitted, it will be assumed that the track section 3T has become occupied by a train so as to causethe dropping away of the track relay 3TB (see Fig. 1C).- The dropping away of that relay causes the dropping away of the relay 3T8 by opening the circuit for" The droppingaway of relay 3T8 connects the center terminal such relay at front contact 68.

C of the battery at location N0. 3 to the common wire ZW upon the closure of back'contact 99 and the indication relay 3TK at the control" OffiCQ becomes energized by a circuit extending from (3+), including back contact Hit of relayBTS,

line wire 3TKW, front contact It! of relay'2TS,.

(see Fig. 1B), back contact I02 of the flashing relay FL, line wire'23TKW, asymmetric device' I93 (see Fig. 1A), winding of relay STK, common wire ZW, and back contact 99of relayIiiTS, to (C).

The picking up of relay 3TK at the'lcontrol oflice applies energy to an obvious circuit for lamp STE at front contact I84. The picking up of relay 3TK opens an obvious circuit which has been closed at back contact [M for charging the.

condenser I65, andthe closure of frontcontact I66 is effective to close a shunt circuit across-the condenser Hi5, including the winding of the bell BK, so as to cause a single stroke of such bell.

The shunt circuit involved in energizing the bell extendsfrom including condenser I05, front contact I08 of relay 3TK,va-symmetric device HIT- and windingof bell BK,ItoQ(-). The inclusion of the asymmetric. device 19'! in the circuit prevents an oscillation to insure the sounding of only a single stroke of the bell.

If the track sections 2'1 and ST become, occu pied contemporaneously, the flashingrelay FL- The flashing relay FL is ener-.

becomes. active. gized under such conditions, bya circuit extends.

ing from G3 1), including backconta'ctrlflfl of relay STS (see Fig. 10), line wire 3TKW,1back.i,

contact 123 of relay ZTS (see Fig. -1B),winding of relay FL, back contact 1590f relay FL, com

mon line wire ZW, and back contact 99 of relay away, theline circuit When the back contact I82 of relay FL is closed, and the relay ZTS is dropped including line wire 2- 3TKW isenergized with. a negative-polarity to. cause the pickingup ofthe relay 2TK; The

circuit b which the ay ZTK is energizedunder i such conditions, 1 extends from (B)', including back contact, H5 lgofv relay 2TS (see-Fig. 1B); back" contact error. the flashing relay F-Lgline wire- 2-3T;KW, asymmetric device l lil- (see Fig.-1A);*

ding. of ,relay..2TK, common line wire--ZW;..J

and backcontact H I :of relay 2TS-, to-(C-). It"

will be notcdrthat such circuitisclosed steadily if the l y ZTS is dropp d away and the-relay 3TS at locationNo. 3 is picked up; butwhenthe relayg 3T5 isalsomdropped away, the flashin srelay is energized by a circuit which has been describedw'ffi tentl-y energized, such relay havingsufiiciently slow drop-away characteristics to cause it to. be maintained steadilypicked up.- It-will be readily apparent that-the relay- 2TK causes the energization of the lamp ZTE and the sounding'of the bell 1 BX in a manner similarto that which has been described for the control of the lamp 3TB andth bell BK by relay 3TK.

During the times when the flashing relay FL is w picked up, the relay-3TK is energized by a circuit extending from (3+); including front contact- IEJZof *the flashing relay FL,-line wire 23TKW,-

asymmetric device I03, winding of relay 3TK, common line wire-ZW;- and back contact 'I ll of relay ZTS, to (C),the relay -3TKhaving slow dropaway characteristics to cause it to be maintainedsteadily picked up aslong as the flashing relay-FL at field location No. 2 is active. It will benoted from the circuits which have just been considered that the indicator lamps are main tained energizeduntil the respective relaysTS that have caused their energization are restored. Inasmuch as such relays can be restored only after the operator has restored the signal controlv levers SGL associated with those locations.to their center positions, the indicator lamps forthe respective track sections will be maintained illuminated until the necessary action is taken on the part of the operator to cause the relays TS responsible for their illumination to be restored to their normally energized positions.

Another means for transmitting the indications to the control oilice is illustrated in Fig. 13. The circuits shown in this figure illustrate asla tive by the closure of back contacts H2 and H3 to energize the line circuit for the control of relays EZ and :Z with a frequency produced by a frequency generator or inverter F of a suitable nature. The closure of back contact I I3 of relay.

3T3 is effective to cause energization of the winding of the'frequency generator F in an obvious manner to cause the energization of the line circuit through the transformer H4 with an alternating current of the particular frequency generated. The frequency generated is sufficiently high as not to affect the operation of the relays tZandZ; and the alternating current is blocked from flowing through the line battery at the con trol oflice by a suitable filter H5. 1

At the control ofiice the relay 3TK is responsive to the energization of the line circuit including line wire 34ZW by an alternating current only if such current is of the frequency generated by the frequency generator F because of its energization through the medium of a tuned circuit including transformers H6 and l I? and the condenser l 8. The condenser l l 9 serves as a blocking condenser to prvent the flow of current from the dlrect current source through the primary winding of the transformer llfiwhenthe linecircuit is energized for the control of the relays 32' and 4Z.

The dropping away of the relay 2T$in response.

v I 7 section 2T at fielding: locat1on'No; 2 is eifectiveto cause the energizato theoccupancy of the track tion-of the-line circuit including line wire 34ZW and-the circuit for relay -2TKisonly intermitwith alternating current of a frequency distinctive fromthe frequency generated in response to the dropping away of the relay 3'IS. Such frequency is produced bythe frequency generator F upon the closure of ,back contact I20, and is supplied to the'line circuit through the transformer l2l in accordance withthe closure of back contact I22 of relay ZTS. The reception at the control office of the alternating current at such frequency is efiective to cause the picking up of the relay 2TK through a circuit tuned to that frequency in a manner similar to that which has been described for the energi'zation of the relay 3TK upon the reception of the alternating current at the frequency generated by the frequency generator F at field location No. 3. I

The circuits by which the lamps ZTE and STE are energized, and the manner in which the bell is sounded upon the reception of the respective indications corresponds to that which has been described with respect to the operation of the relays 2TK and 3TK shown in Fig. 1A.

Having described a centralized trafiic controlling system for a particular stretch of track'way as one specific embodiment of the present invention, it isdesired to be understood that this form is selected to facilitate in the disclosure of the invention rather than to limit the number of forms which the invention may asume; and it is to be further understood that various modifications, adaptations and alterations 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 in vention except as limited by the appending claims.

What we claim is:

1. In a centralized traffic controlling system for said neutral or said first position, signal control means including said line circuit for causing the signal at'the opposite end of said stretch for governing trafiic out of said stretch to indicate proceed when and only when said signal control lever is in either said neutral or sa d second position, signal control means including said line circuit for causing the signal at said one end of said stretch for governing traflic into said stretch to indicate proceed only when said signal control lever is in said second positiomlsignal control means including said line circuit for causing the signal at said opposite end of said stretch for governing traffic into said stretch to indicate proceed only when said' signal control lever is in said first position, and means acting to prevent each signal control means from causing its associated signal to indicate proceed .if the trackway immediately in advance of such s gnal is occupied by a train. 7

2. In a centralized traific controlling system of the character described for a stretch of track having a signal at each end for governing'entrance thereto, a signal control lever at a control ofiice having a neutral position and respective first and second signallclearing positions, a line circuit extending from the control office to the ends of said stretch, a self-restoring manually operable contactor at each end of said stretch having a contact closed only while such contactor is manually actuated, circuit means including said line circuit for causing said signal at one end of said stretch to clear when and only when said controllever at the control oiiiceis actuated from said neutral position to said first signal clearing position at a time when said contactor at that signal is manually maintained in its actuaated position, circuit meansincluding said line circuit for causing said signal at the opposite end of said stretch to clear when and only when (1 control lever at the control office is actuated from said neutral position to said second signal clearing position at a time when said contactor at that end of the stretch is manually maintained in its actuated position, and means acting on the circuit means for each signal to prevent the clearing of that signal if the trackway immediately in advance of such signal is occupied by a train.

3. In a centralized traflic controlling system for railroads for a stretch of double track having a signal at each end thereof for governing traific out of such stretch against the normal direction of tratnc, a manually operable signal control lever distinctive neutral and signal clearing positions,

a self-restoring manually operable contactor at each end of said stretch having a contact closed only while such contactor is manually actuated, a line circuit extending from the control omce to each end of said stretch, circuit means including said line circuit for causing said signal at each end of said stretch to clear when and only when said signal control lever at the control oifice for that end is actuated from its neutral to its signal clearing position at a time when said contactor at either end of said stretch is manually maintained in its actuated position, and means for preventing each signal from being controlled to a clear indication by its associated circuit means if the trackway immediately in advance of such signal is occupied by a train.

4. In a centralized traffic controlling system for railroads for a stretch of double track having a track switch at each end connecting the double track to single track portions, a signal at each end of said double track stretch governing train movements over the track switch at that end to the adjoining single track portion, a signal control lever at a control oflice for each of said signals having distinctive signal stop and signal .clearing positions, a self-restoring manually accontactor at either end of said double track is fective upon the acceptance of either of said signals by a train to allow such signal to indicate proceed again only after said lever at the control ofiice for that signal has first been actuated to its stop position,

the character described for a stretch of double track connected at. each end to a portion of single track by ahand-throwlswitch normally aligned for traflic to the .right'through such double track stretch, a signal at:eachend-of said stretch for governingentrance to that stretch in the normal direction of traffic, a signal at each end of said stretchfongoverningentrance tothat stretch against the normal direction of traffic, a

signal 'control' lever 'at-a distant control ofl'ice for each end of said s'tre'tchhaving distinctive stop and signal clearing positions, signal control means for causing the signal at each end of said stretch for governing trafiic in the normal direction through said double track stretch to clear in accordance with the unoccupied condition of the trackway in advance thereof, and signal control means for causing said signal at each end of said stretch for governing entrance to that stretch against the normal direction of traflic to clear only when said signal control contactor at the control oflice for that end of said stretch is actuated to its signal clearing position, such means being effective to clear that signal only after the track switch at that end has been in its reverse position for a predetermined length of time.

6. In a centralized traffic controlling system for railroads for a stretch of track having a signal at each end for governing entrance thereto, a signal control lever at a control ofiice having a neutral position and respective first and. second signal clearing positions, a line circuit extending from the control ofilce to both ends of said stretch, a self-restoring manually operable contactor at each end of said stretch having a contact closed only while such contactor is manually actuated, circuit means including said line circuit for causing said signal at one end of said stretch to clear when and only when said control lever at the control oifice is actuated from its neutral position to its first signal clearing position at a time when said contactor at that signal is manually maintained in its actuated position, circuit means including said line circuit for causing said signal at the opposite end of said stretch to clear when and only when said control lever at the control ofl'lce is actuated from its neutral position to its second signal clearing position at a time when said contactor at that end of the stretch is manually maintained in its actuated position, means acting on each of said circuit means to prevent either signal from indicating proceed if the trackway immediately in advance of such signal is occupied, and means eifective upon the acceptance of either of said signals by a train to allow such signal to clear only after said lever at the control office for that signal has first been actuated to its stop position.

7. In a centralized trafiic controlling system for railroads for a stretch of single track having signals at each end thereof for governing trafiic into said stretch, a signal control lever at a control ofiice having a neutral position and respective first and second signal clearing positions, a

neutral polar relay at each end of said stretch,

a single line circuit connecting the control oflice and the respective ends of said stretch for controlling the neutral polar relay at both ends of the stretch, means for energizing said line circuit at the control office with one polarity when said signal control lever is actuated to said first position, means for energizing said line circuit with the opposite polarity when said signal control lever is actuated to said second position,

. I 9, means for deenergizing said line "circuit when said signal control lever is actuated to saidineutral positidnQsignal control means at. one end-of said stretch: for causing the signals governing the entrance oftrafiic at that end to indicate proceed only when said neutral polar relay at that endis energized with the said one polarity, signal control means at'the other end of said stretch for causing'the'signals governing the entrance of traffic at that end in the opposite direction to indicate proceed onlywhen said neutral polar relay at that end is energized with said opposite polarity, means governing both of said signal control means to prevent the clearing of their respective signals if the trackway immediately in advance of such signal is occupied, and means associated with said signals at opposite ends of said stretch effective upon the acceptance of a signal at either end of said stretch by a train to allow such signal to indicate proceed for a following train only after said neutral polar relay for that end has first been deenergized and then reenergized with the appropriate polarity,

8. In a centralized traffic controlling system for a single track railroad having successive stretches of double track connected by a stretch of single track with signals governing the entrance of traffic into each single track stretch for each direction of trafiic, a single signal control lever of the three-position type for each stretch of single track, a neutral polar relay at both ends of each single track stretch, a single line circuit connecting in series said relays for each single track stretch to the corresponding signal control lever in the control oifice', means for energizing each line circuit with one polarity or the other when its associated signal lever is operated to one or the other of two operated positions and for deenergizing that line circuit when such lever is in a non-operated position, and signal control means associated with each of said single track stretches and governed by the respective neutral polar relay for the opposite ends of that stretch to effect the clearing of the signal for one direction of traffic when the corresponding line circuit is energized with one polarity and to effect the clearing of the signal for the opposite direction of traflic when such line circuit is energized with i the opposite polarity but holding such signals at stop when such line circuit is deenergized, said signal control means associated with each stretch of single track acting to prevent the clearing of a signal governing the entrance of traffic into the stretch if a train occupies that stretch immedi ately in advance of such signal.

9. In a centralized trafjc controlling system for a single track railroad having successive stretches of double track connected by stretches of single track with suitable track switches normally positioned for the movement of traffic out of the stretches of single track into the opposite ends of a stretch of double track in such a manner as to permit the passing of opposing trains to the right of each other, entering and. leaving signals at each end of each double track stretch for governing trafi'ic into and out of said double track stretch respectively, a single signal control lever for each stretch of single track, a polarized sigand other signal control means associated with each double track stretch for normally clearing each entering signal'to allow .trafic to proceed through the double track stretch to the next leaving signal, said'other signal control means acting on said first signal control means to restore an entering signal to stop when the associated signal control relay is energized withthe polarity required for clearing'the opposing leaving signal,

ROBERT M. PHINNEY. GORDON w. DAVISON.

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