US2320792A - Railway traffic controlling apparatus - Google Patents

Description

June 1, 1943. J. M. PELIKAN RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Dec. 30. 1941 D. \Eq ,3 .QN wmfi WEN m v5 onuw L 3% v5 +kwm H 5 .E w 2 1 m 2% MHGQ w W w W E wk 4 An 5 5 m VP .1 m A, W

Patented June 1, 1943 UN TE STAES FE ZC,

RAILWAY TRAFFIC CONTROLLING APPARATUS John M. Pelikan,

Chicago, Ill., assignor to The Union Switch and Signal Company, Swissvale, Pa, a corporation of Pennsylvania Application December 30, 1941, Serial No. 424,901

8 Claims.

My invention relates to railway traffic controlling apparatus for governing the movement of trafiic over a stretch of railway over which traffic moves in both directions, and more particularly to apparatus for signaling on a single track railway using a centralized trafiic control system.

My invention is in the nature of an improvement on the invention of an application for Letters Patent, Serial No. 412,627, filed September 27, 1941, by Henry S. Young, for Railway trafic controlling apparatus, and in which application there is disclosed an absolute permissive block signal system employing circuits using two line wires which may be energized at one end or the other for establishing the direction of traffic over an associated stretchof railway, such directional control being manually governed from a central point by means of a centralized traflic control system.

Railways using'a centralized traific control system often have a siding that is used so little it does not warrant being fully equipped with signals and power switch machines, but which siding is used often enough that to abandon such a siding is unwise.

Accordingly, a feature of my invention is the provision of novel and improved railway trafiic controlling apparatus for protecting traific movements from a siding of a railway using a centralized traffic control system.

Another feature of my invention is the provision of novel and improved railway traffic controlling apparatus for governing leaving signals ata siding of a railway using a centralized traific control system, it-being contemplated that handthrow switches are provided for the siding and a train enters the siding under telephone orders or similar instructions, but leaves the siding by signal indication.

Still another feature of my invention is the provision of apparatus of the type here contemplated for governing the leaving signals of a siding of a single track railway through the medium of a two-wire line circuit of an associated absolute permissive block signal system and additional line circuits and track circuits are not required. 7

Again, a feature of my invention is the provision'of novel railway traffic controlling apparatus for governing traffic movements entering a block of a single track railway over a switch at a location intermediate the opposing block signal 10- cations.

My invention also includes the provision of novel lockout means at the centralized traffic control office to prevent the transmission of a code to clear a leaving signal at a siding within a block of a single track railway when the block section at either side of such siding is occupied by a train approaching the siding or either of the two opposing block signals is cleared for a train to enter the block.

Other features, objects and advantages of my invention will appear as the specification progresses. A

The above features, objects and advantages em-' bodying my invention I obtain by providing a leaving signal at a track switch over which traflic may enter ablock at a location intermediate the,

siding, and thestorage unit is provided'with the usual code controlled stick relays, one such relay for each leaving signal to becontrolled. When any one of the code controlled stick relays is picked up, a repeater relay is energized and picked up. Contacts of this-repeater relay are interposed in the two-wire line circuit of the associated absolute permissive block signal system, so ,that when the repeater relay is picked up the line circuit extending along the section within which the particular track switch is located is opened and special control relays are connected thereto,

a special control relay being connected to each end of the line circuit. In the absolute permissive block signal system here involved, the line circuit is a reversible circuit extending between the block signal locations of the associated block but sectionalized at each intermediate signal location. That is, this line circuit comprises a series of sections or individual circuits which are controlled in tandem and to which a current source is connected at one end or the other according to'the direction of trafiic established by the associated centralized traffic controlsystem, and when any individual circuit of suchline circuit is opened ata point intermediate its two ends, the current source at each end of .such individual circuit is' connected across the line wires. This line circuit" includes a contact of each track relay of each.

track section of the block and consequently when the repeater relay is picked up to open a particular section of the line circuit and connect special control relays one to each end of the particular section of the circuit, both of these special control relays are energized if the track sections at each side of the track switch or siding are unoccupied by a train approaching such track switch or siding and if neither one of the opposing block signals is cleared to permit a train to enter the block. Each such leaving signal is governed by a first signal control relay which is energized over a circuit including in series a front contact of the two special control relays and a front contact of the respective code controlled relay. This signal control relay when picked up completes an operating circuit for operating the leaving signal to a special safe to leave indication position, such indication informing the train crew that it is safe to enter the block over the respective track switch. Another or second signal control relay is provided for the leaving signal and is controlled over a contact of the usual switch circuit controller of the associated track switch in series with the circuit of the first mentioned signal control relay, and when a trainman operates the track switch in preparation for the train to enter the block, the leaving signal is operated from the safe to leave indication to a position for displaying the usual approach signal indication. The train upon entering the track circuit adjacent the track switch shunts the associated track relay to open the two-wire line circuit in the usual manner, and thereby causes the respective special control relay to be deenergized, which upon releasing deenergizes both signal control relays of the' associated leaving signal, operating the leaving signal back to its usual stop indication. The code controlled relay is retained energized over a stick circuit governed by the special control relays and when either special control relay is released in response to the train leaving the siding, the code controlled relay and the other special control relay are restored to their normal positions. When the train has entirely moved over the track switch and the trainman has restored the switch to its normal position, the two-wire line circuit is then in the condition that corresponds to a train in the block and moving in the corresponding direction.

A lockout circuit is provided in the control machine at the centralized traffic control office to prevent the transmission of a code to select the code controlled relay of the line code storage unit associated with the respective switch or siding when the block section in which such track switch is located is occupied or a signal has been cleared to permit a train to enter such block.

I shall describe one form of apparatus embodyingmy invention, and shall then point out the novel features thereof in claims.

The accompanying drawing is a diagrammatic view showing one form of apparatus embodying my invention when applied to a railway using a centralized traffic control system for governing the. direction of traffic over a stretch provided with an absolute permissive-block signal system which employs a two-wire line circuit of the form here involved. 1

Referring to the drawing, at the top portion there is illustrated a stretch of single track railway extending between theladjacent ends of two fullysignaled sidings PSI and PS3, and within which. stretch another siding PS2 is located, it being understood that siding PS2 is one that does not warrantbeing fully signaled.

This stretch of railway which constitutes a block is formed by the usual insulated rail joints into a series of consecutive track sections identified by the reference character T plus a distinctive numeral, and is provided with the usual arrangement of wayside signals. As here shown, signal 2RA or ZRB at siding PSI and signal ILA or ALB at siding PS3 are opposing block signals for a block including track sections IT, I IT, IZT, I3T, I5T and ST, and each of which sections is provided with the usual closed track circuit, of which track circuits only those for sections I3T and HT are shown. The spacing of trains moving in the same direction through the block is governed by intermediate signals I2 and I 4 for eastbound traflic, and by intermediate signals I3 and II for westbound traiiic. Furthermore, signals 2L and 4R function as entering signals at sidings PSI and PS3, respectively. Specifically, the track diagram and related signals of the accompanying drawing correspond substantially to the track diagram and related signals disclosed by the aforementioned application Serial No. 412,627, and for the sake of clarity the track sections and signals of the accompanying drawing are given the same reference characters as the corresponding track sections and signals of application Serial No. 412,627. It is to be observed, however, that in the accompanying drawing, track sections IGT and MT have been omitted and siding PS2 is located in track sections I2T and I3T. Track switches ISW and 3SW at sidings PSI and PS3, respectively, may be power operated switches, but switches ASW and BSW of the siding PS2 are preferably hand-throw type of switches. According to my invention, two leaving signals IL and IR are provided at siding PS2, signal IL governing train movements from the siding into the block over switch ASW, and signal IR governing train movements from the siding into the block over switch BSW.

In order to simplify the drawing and to enable the circuits to be more readily traced, I have herein identified each relay by a letter or combination of letters with a prefix identifying the signal, switch or track section with which the relay is associated. The sources of current for energizing the various circuits are identified by the reference characters B and C which refer to the positive terminal and to the negative or common return terminal, respectively. Furthermore, in many instances a relay contact is shown remote from the relay winding and in each such instance the contact is provided with a reference character corresponding to that for the respective relay, plus a distinctive numeral. Also, the operating circuits for the different signals except the leaving signals IL and IR are not shown since these operating circuits would be in accordance with standard practice and form no part of my invention.

The various signals of the accompanying drawing, except signals IL and I R, are preferably controlled by circuits similar to those disclosed in the aforementioned application Serial No. 412,627, and in the accompanying drawing only the portion of these circuits required for a full understanding of my invention is shown and reference is made to application Serial No. 412,627 for a full description of such signal circuits. It is sufficient for my present application to point out that these control circuits include a reversible twowire line circuit extending from the location of block signals ZRA and ZRB to the location of the opposing block signals ALA and ALB, but is sectionalized at the location of intermediate signals I I and I2 and at the location of intermediate signals I3 and I4. That is, this line circuit comprises three sections or individual circuits arranged in tandem, a first one of which extends from the location of block signals 4LA and 41B to the location of intermediate signals [3 and: M, a second one extends from the location of intermediate signals l3 and M to the location of intermediate signals 1 I and I2, and the third, one extends from the location of intermediate signals l I and I2 to the location. of block signal ZRA or ZRB. This line circuit is controlled by the track relays of the several track sections, each individual circuit being controlled by the track relays of the track section-s along which that individual circuit extends. The line circuit is further controlled by directional relays, one at each of the block signal locations, and which directional relays are governed in turn by a centralised trafl'i'c control system. For example, eastbound trail-lo is established when a directional relay at block signal: ZRA is released and a directional relay located at block signal ALA is energized by proper codes of the centralized trafiic control system. Such condition of the directional relays causes a current source to be connected to the east or right-hand end, as viewed in thedrawing, of each section of the line circuit to energize a linerelayat the west or left-hand end: of the respective line circuit section, this condition being eiiected: progressively starting at the east end of the-block.

Similarly, westbound traffic is established when the-condition of the directional relays at the block: signal locations is reversed in response to proper codes of the centralized traffic control. system. When westbound direction for trafiic is thus selected, a current source is connected to' the west end of each of the. sections ofthe line-- cir-' cuit to energizea line relay at theseast end of: the respective section of the circuit. Such action is effected progressively starting at the west end of the: block. Current of normal or reverse polarity is suppliedto therespective sections of the line circuit to7provide-control for three-position wayside-signalsin the usual manner, the.- polarityof the'cu-rrent being; governed by means of the-usual directional stick relays of the-absolute permissive blo'ck'signal system.

Since. the siding PS2. is located within the stretch between. the location ofintermediate' signals H and I2 and thelocation ofintermediate signals' l3. and l t, the section of the two-wire line circuit. extending along this associated: stretch. of the-track only is shown complete-together with theleft-handend. of the line circuit section ex.-

tending betweenthe-location-of block signal 4LA and the. location: of. intermediate signals 13 and.

14,. and the right-hand end. of the sectionot the line circuit extending from the location of. the block signal ZRA. to. the. location of the inter-- mediate signals H and l2...

In. other words, the control of leaving signals IL and IR at siding PS2 directly involves the sec.- tionofthe. two-wire line circuit extending alon the tracksections within which siding PS2 is. confined, and a. description of. this section of the two-wire line circuit, together with. its relation ship to. theadjacentsectionsis sufiicient for a full understanding. ot my. invention.

The line. circuit. for the. block. disclosed in the:

drawing is shown as conditioned for eastbound traflic and hence current issupplied=to line wires LI and. L2 of the sectionv of the line circuit ex.- tending. from block signal. 4LA to intermediate signals 1-3 and I land a line relay MHR is.ener-- gized. Relay MHR. controls a, slow acting repeater relay MHP' over an. obviouscircuitinclud- 75 of the same source of current.

that this-section of the line circuit iscontrolled ing. front contact. Z-Oof relay MHR'. Relay" M'HP onpicking up'connects the current source to the next adjacent section of the line circuit, that is, to the section of the line circuit extending from the-location of signals l3 and I4 to the location of signals II and I 2,. and within which stretch of track the siding PS2 is located. This last men-- tion'ed section of the line circuit can be traced fromterminal B- over resistor 2 l; front contact 22' of relay I ll-1P, front contact- 24 of track" relay ISTR-of section I3T, line wire L3a, backcontact' 25 of a repeater relay I-ISP to be referred tolater, back contacts 26am! 2'! of relays lRSR-and IRHR associated with leaving'signal IR as will be later explained, contact 23 operated by the track switch BSW and closed only when the switch- BSW is set at its normalposition, front contacts 29 and 300i relays ILRP and ANP'associa-ted with signal IL and switch ASW as will shortly appear, a second back contact 31 of repeater relay HSP, line wire L31), front contact 32 of track relay IZTR of track section IZT, back contacts 33 and 35' of relays HHP and HS associated with signal l l as willlater appear, line relayl 2H-R, back contacts' 36.and 3 1 of relays HS and ll'HP,.respec tively, front contact'38 of track relay IZTR, line wire Lb, back contacts 89- and 40 of repeater relay HSP, front contact 4| of track relay I3'I'R and front contact-42 of relay MHP to terminal C by the sectionof the linecircuit next'to the right,. by trailic in the track sections IZT and l3T, by the position of the trackswitches ASW and BSW,

. and also by the position. ofrepeater relay HSP.

Normally, line relay I2HR is pickedup-and controls aslow acting repeater relay l2-HP over an obviouscircuit including front contact 43 of rela-y IZHR. Relay L2H? on picking up controlsat its front contacts 44- and 45 the connection of the current. source tothe section of the line circuit next to the left and which includes line WiresLS' and-L6 extending to the location of. block signal ZRA.

When westbound direction of-tramc is established and a current source is. connected to line wires L5 and L6 at the left-hand end of the block, line relay ill-IR. is energized because repeaterrelay L2H is released to connect relay HHRto line wires L5- and L5, and. relay III-IR on picking. up completes a simple circuit for an associated slow acting repeater relay HHP, and relay H-HP on picking up to close front con tacts 3 and 5 connects, in. turn, terminals-B and- C of. the associated currentsourceto line wires Lab. and M11 of the circuit extending from location of signals H and H! to the location: of si nals l3 and 5- withthe result that line. relay IBHR. is energized over this section of the-line circuit extending through tracksections I ZT and HT. and explained. above in: detaiL- Linerelay ISHR on. picking up completes a simple. circuit for its associated repeater relay EEHP, and relay L8H? on picking. up connects terminals 3- and C of the associated current source tolinewires L! and L2.

It is to be pointed. out that when westbound. direction of trafiio is established, and relay H HR and HHP become released. due. to. awestbound train entering section HT, the. stick relay HS associated. with. westbound sierra]. it is picked.

up through the absolute permissive. block signal It isto be observed become released due to an eastbound train entering section IBT, stick relay MS, associated with signal [4, is picked up in the usual manner by the absolute permissive block signal systern and pole changes the connection of terminals B and C to the respective'line wires L3a and Ltd. The manner of employing the section of the line circuit extending along track sections [2T and l3T for governing leaving signals IL and IR will be taken up and described in detail shortly.

The centralized traffic control system may be any one of several well-known arrangements. For example, it may be of the impulse code type covered by Letters Patent of the United States No. 2,229,249, granted January 21, 1941, to L. V. Lewis, for Remote control system. In such centralized traffic control system control is efifected between a central ofiice and various stations located along the railway over a. pair of line wires commonlyidentified as line wires Y and Z and which line wires extend from the oifice to each station so that control codes transmitted from the ofiice are received at each station to effectively operate a line code storage unit at the station for which the code is intended. The line code storage unit when operated effectively energizes code controlled stick relays according to the code received, and the selected stick relay in turn governs a corresponding signal or other device. A control code is initiated by operating a lever of the machine at the office, an operation of the lever completing a circuit which causes an office coding unit to deliver a corresponding code to the line wires Y and Z.

The centralized traffic control system is shown only as required for an understanding of my invention. Referring to the drawing, the dot and dash line rectangle bearing the legend C. T. C. oiiice represents the office of the centralized trafiic control system. The numerals I, 2 and 4 designate signal levers of the office 7 machine, each of which levers is operable to a normal position indicated by full lines in the drawing, and either to a left or to a right position indicated by dotted lines in the drawing. As will appear later, lever l is used to control leaving signals IL and IR at siding PS2, lever 2 is used to control signals ZRA, ZRB and 2L at siding PSI, and lever A is used to control signals ILA, 41B and 4R at siding PS3. These levers operate circuit controlling contacts over which circuits are completed for the office coding unit, which in turn functions to deliver to wires Y and Z a code made distinctive for each of the diiferent positions of the levers.

The dot and dash line rectangle bearing the legend 0. T. C. station No. 2 designates a station located at siding PS2. The location of such a station may be at either end of the siding, and as shown in the drawing it is located at the east end. Two code controlled stick relays ILHS and IRHS are controlled by station No. 2. When lever I is moved to its left-hand position to close a contact L48 and an office relay IS to be later described is picked up closing front contact 95, the oilice coding unit delivers a code to wires Y and Z which is received at station No. 2 to cause positive energy to momentarily appear at a terminal 49 and to remain on a terminal 59. During the reception of such a code and terminal 49 is made positive, current flows through an operating winding of relay lLHS to terminal C and that relay is picked up. Relay ILHS when traflic is established and relays HR and IAHP thus picked up is retained energized by a stick.

circuit extending from terminal 50 over front contact 51 of relay ANP, contact 52 operated by switch BSW and closed at the normal position of the track switch, back contact 53 of relay IRHS, front contact 54 and winding of relay ILHS to terminal C. Lever I when operated to its right-hand position to close contact R55,

causes the oflice coding unit to deliver a code to the line wires Y and Z which is received at station No. 2 to cause positive energy to momentarily appear on a terminal 56 and to continue on terminal 59. Current flows from terminal 58 over the operating winding of relaylRHS to terminal C and relay IRHS is picked up in response to this code. tained energized subsequent to the code over a stick circuit extending from terminal 50 through front contact 5| of relay ANP, contact 52 operated by switch BSW, back contact 51 of relay ILHS, front contact 58 and winding of relay IRHS to terminal C. It is to be pointed out that a circuit path comprising front contacts 59 and E6 of two special control relays BBB and LDR.

to be shortly described, serves to shunt the stick circuits of relays ILHS and IRHS around front contact 5! of relay ANP and contact 52 of switch BSW. A repeater relay HSP is controlled by code controlled relays ELI-IS and IRHS, relay HSP being picked up over a simple circuit'ineluding either front contact 6| of relay ILI-IS or front contact 62 of relay iRHS. Thus repeater relay HSP is manually controlled through the medium of the centralized trafiic control system and is picked up whenever either code controlled relay lLl-IS or IRHS is selected.

Contacts of repeater relay HSP are interposed in the section of the line circuit extending along track sections HT and I3T as pointed out hereinbefore. That is to say, back contacts 3| and 39 of relay HSP are interposed in line wires L3?) and L4!) and back contacts 25 and 40 of relay HSP are interposed in line wires L3a and L la. Thus when relay HSP is picked up it serves to open the In addition associated line circuit at two points. to this it connects two special control relays LDR. and RDR to the circuit, one to each end of the circuit. To be explicit, when relay'I-ISP picks up opening back contacts 3| and 39, the relay LDR is connected to the left-hand end of the circuit over front contacts 63 and 64 of relay HSP and relay LDR is picked up by the current source at the left-hand end of this section of the line circuit. Similarly, when relay HSP is picked up to open the line circuit at back contacts 25 and 40, relay RDR is connected to the right-hand end of this section of the line circuit over front contacts 65 and 66 of relay HSP, and relay RDR is energized by the current source at the right-hand end of this line circuit section. It is to be observed that relay RDR is energized unless relay HP is released because the section of the line circuit including line wires LI and L2 is open due to a westbound train occupying track section ST or I5T, or because the directional relay at the east end of the block has been picked up by the centralized trafiic control system for clearing the block signal 4LA or ALB for a westbound train. If relay MHP is released, due to an eastbound train moving through section I5T, the relay RDR Relay IRHS is then re-- lished, the opening of the line circuit at a mid point such as back contacts 3| and 39 of relay HSP, causes line relay IZHR to be deenergized and released so that relay I2HP is in turn released to open the next adjacent section of the line circuit and in turn cause the line relay at the west end of the block to be released with the result the associated directional relay (relay 2RDR of Fig. 1A of Serial No. 412,627) is picked up and connects the associated current source to the west end of line wires L and L6. This energizes relay l IHR and in turn relay I IHP, so that relay III-1P is picked up closing front contacts 3 and 5 to connect the associated current source to line wires L3b and L4!) with the result that special control relay LDR is energized and picked up. Relay LDR is not energized when relay IIHP is released because the section of the line circuit including line wires L5 and L6 is open due to an eastbound train occupying section IT or T, or

signal ERA or 2RB has been cleared by means of the centralized trafiic control system. In case relay I IHP is released due to a westbound train in section I IT, then special control relay LDR is energized because stick relay I IS is now picked up in the usual manner and connects the current source to line wires L31) and Lb.

In the case westbound traffic is established at the time the repeater relay HSP is picked up in response to a code, then the opening of the line circuit at a mid point, such as back contacts and of relay HSP, causes relays I3I-IR and I3HP to be released to disconnect the current source from line wires LI and L2 and deenergize the associated line relay at the east end of the block and cause the associated directional relay (relay 4LDR of Fig. 10 of Serial No. 412,627) to be picked up to connect the associated current source to the line Wires LI and L2. Relays I 4HR and I lHP are now energized and picked up connecting the B and C terminals to the line wires L3a and L la and special control relay RDR is energized.

The special control relays LDR andRDR, together with the code controlled relays ILHS and I RHS serve to govern signal-control relays for the leaving signals IL and IR. When code controlled relay ILI-IS is selected and special'control relays LDR and RDR are picked up by the line circuit as explained above, a circuit is formed for a signal control relay ILSR of signal IL, this circuit extending from terminal B over front contact 6! of relay RDR, front contact 68 of relay LDR, front contact 59 of relay ILHS, back contact Hi of another signal control relay ILHR for signal IL, winding of relay ILSR and to terminal C. Leaving signal IL is preferably a three-position color light signal, and relay ILSR when picked up closing front contact II completes a simple operating circuit for a lamp S of signal IL, and the lamp S is illuminated to display a special safe to leave indication. Switch ASW would next be reversed by a trainman in preparation for a train to leave siding PS2 in response to leaving signal IL displaying its safe to leave" indication, and a circuit is formed from terminal B over front contacts 61, 6B and 69 in series, contact I2 operated by switch ASW and closed only when switch ASW is at its reverse position, winding of relay ILHR and to terminal 0. Relay 'ILHR when picked up opening back contact 10 deenergizes relay ILSR. An operating circuit is now formed extending from terminal B over back contact 73 of relay ILSR, front contact I4 of relay ILHR, lamp Y of signal IL and terminal C, and lamp Y is illuminated to display an approach indication. Under normal conditions both relays I-LSR and I LHR are released, closing back contacts I3 and I5 to complete an operating circuit for lamp R of signal IL and that lamp is illuminated to display a stop indication.

When code controlled relay IRI-IS is selected and special control relays LDR and RDR are picked up by means of the line circuit in the manner explained hereinbefore, a circuit is formed for a signal control relay IRSR for signal IR, this circuit extending from terminal B'over front contacts 61 and 63 of relays RDR and LDR, respectively, front contact I6 of relay IRHS, back contact ll of another signal control relay IRHR for signal IR, winding of relay IRSR and to terminal C. Relay IRSR on picking up closing front contact I8 completes an operating circuit for lamp S of signal IR and that lamp is illuminated to cause signal IR to display its safe to leave indication. When track switch BSW is reversed by a trainman, in preparationfor a train to move from siding PS2, a circuit is formed for signal control relay IRHR, such. circuit including terminal B, front contaCts'B'I, 58 and 16, contact 79 operated by switch BSW and closed only at' the reverse position, winding of relay I BER and terminal C. Relay IRHR on picking up opens the circuit for relay IRSR, and with relay IRSR released and relay I RHR picked up, an operating circuit is formed' over back contact 80 of relay ERSR and front contact 8| of relay IRHR for lamp Y of signal IRandthat lamp is illuminated to display an approach indication; Normally, lamp R of signal IR is illuminated over a circuit completed at back'contacts'8l and 82' of relay IRSR and IRHR, respectively. 7

The positions of switches ASW and BSW and of the leaving signals IL and IR are checked by the line circuit of the associated block. Relay ANP is normally energized over an obvious circuit including contact 83connec'ted to switch ASW and closed only at the" normal position of this" switch, andfron't contact 30 of relay ANP is interposed in the line circuit,- as explained here'inb'eforel Contact 28 operated by switch BSW is included inthe" line circuit to check the position of switch BSW. A repeater relay ILRP is controlled over a; circuit including in series back contacts Stand 85' of thesi'gnalcontrol're lays ILHR and ILRS, respectively, of signal IL, and front contact 29 of relay ILRP is'in'terposed in the line circuit. The position of signal IRis checked by' the fact that'back contacts '26 and 2'! of signal control relays IRSR and IRI-IR are interpo'sed in the line circuits.

In describing the operation of the system, I shall assume that the apparatus is in'the posi tion illustrated in the drawing, that is, the line circuit is conditioned for east-bound trafiic'. I shall also assume that the block isun'occupi'ed, the block signals are a't'stop, and that signal levers 2 and 4 atthe office are set'at'their normal positions. I shall next assumethatit is desired to move a train from siding PS2 over the track switchASW. To .do this, the operator moves lever I to the left position where a lookout circuit is closed for relay IS, such lockoutcircuit including terminal B,lever cbntatfL-Bfi or lever I, contacts NL8I and Nit-8801 levers Band .4; 89; BI]; 9.'I and 92"o"fi indication relays (not shown) for theblock f and" respectively, back contacts block signals as described in-the' previouslyreferred to application Serial No; 412,627, winding .code controlled relay ILHS and relay ILHS on picking up completes its own stick circuit by which it is retained energized subsequent to the code. Repeater relay HSP now picks up to open the line circuit at two places and to connect the special control relays LDH and RDR to the respective ends of the line circuit. Relays LDR and RDR are picked up because the block is unoccupied, and the block signals are at stop, and

these two relays in connection with the code controlled relays ILHS complete the circuit for the signal control relay ILSR, which on picking up operates signal IL to display its S lamp as an indication that it is safe for the train to leave the siding. A trainman now throws switch ASW to its reverse position, and with switch ASW reversed, relay ILHR is selected and signal IL is operated to display its Y lamp as an approach signal indication. It is to be noted that when switch ASW is reversed, relay ANP is released, and also that when signal control relays ILHP and ILSR are picked up, repeater relay lLRP is released, but such operation of these relays at this time does not disturb the line circuit because relay HSP on picking up opens the circuit at points outside of the control of the relays ANP and ILRP. It is also to be noted that code controlled relay ILHS is retained picked up over the path including front contacts 59 and B0 of relays BBB and LDR subsequent to operation of switch ASW. The train upon entering track section I2T shunts track relay IZTR. which opens the line circuit and releases special control relay LDR and that relay upon releasing in turn deenergizes the signal control relay ILI-IR to restore signal IL to its normal stop position. Relay LDR when released also opens the stick circuit for code controlled relay ILHS with the result that relay ILHS is released causing repeater relay HSP to be also released. This operation results in the line circuit being restored to its normal condition, that is, to the condition corre-' sponding to a westbound train occupying section IZT. When the train has fully. moved out of the siding PS2, the trainman restores switch ASW to its normal position.

.It is to be observed that relays IZHR and IZHP are released when the line circuit is opened by operation of repeater relay ESP, and consequently the eastbound signal I2 is set at its stop position. However, relays IIHR and III-1P are picked up and westbound signal II isoperated to its proceed position so that the train moving out of the siding over switch ASW is given a proper proceed signal indication at the westbound signa1 II. Furthermore, operation of signal IL will be effected through stick relay I IS in the event there is another westbound train moving in section I IT.

In the event the train on siding PS2 is to move east, then the operator moves lever I to its right position closing lever contacts R% and Rr-55.

Lockout relay IS is now picked up over the lockout circuit closed at lever contact R95 and relay IS when picked up completes at its front contact 94 a circuit for the office coding unit, and a code is delivered to line wires Y and Z which selects code controlled relay IRI-IS at station No. 2.

Relay IRI-IS' on picking up energizes repeater re- :lay HSP, and relay HSP oh picking up opens the line circuit and connects special control relays IR to display its Y lamp as an approach signal indication. While the operation of switch BSW and relays IRSR and lRHR' opens the line cir cuits, it does not disturb the condition of relays DLR. and RDR since the point at which the line circuit is opened by repeater relay HSP is outside of the control of switch BSW and the relays associated with signal IR; Furthermore, code controlled relay IRHS is retained picked up over the circuit path including contacts 59 and B0 of the special control relays, after switch BSW is reversed. The train upon entering the track circuit of section l3T shunts track relay ISTR and opens the line circuit to deenergize relay RDR with the result that signal 1R is set to display its stop indication, and relays lRI-IS and HSP are restored to their normal positions. Since relays MHR and MHP are picked up, the eastbound signal I4 is controlled to a proceed position for the train moving out of the siding over switch BSW. Switch BSW is restored to its normal position by the-trainman when the train has completely left the siding and the line circuit is then restored to the position corresponding'to an eastbound train moving through the block and occupying sectionI3T. e

It is clear that the lockout circuit for relay IS at the office cannot be picked up to send a code to' station No.-2 unless both levers 2 and 4 occupy-their normal positions and unless the network c-ontrolled by the associated indication relays is closed.

Apparatus embodying my invention has the advantage that movements from a rarely used siding of a railway using a centralized traffic control system can be governed by signal indication without additional line circuits or additional track circuits and the expense of fully signaling such siding is avoided.

Although I have herein shown and described onlyone form .of railway trafiic controlling apparatus embodying my invention, it is understood thatv various changes and modifications may be made therein within the scopeof the appended claims without departing from the spirit and scope of my invention. Having thus described my invention, what I claim is: I

1. In railway traffic controlling apparatus the combination comprising, a .stretch of railway track over which traffic moves in both directions and including a passing Siding, a two-wire line circuit extendingalong said stretch controlled by trailic occupying the stretch and adaptable of be- 7 ing, connected to a current source'at one end or the other to establish the direction for trafiic to move through the stretch, a leaving signal at each end of the siding to govern trafiic entering said stretch from said siding, two control relays, manually controlled means including a repeater relay effective when picked up to open said line circuit and connect said control relays one to each end portion of the line circuit, and operating means for said signals controlled by said manually controlled means and said control relays to selectively operate one or the other of said leaving signals.

2. In railway trafdc controlling apparatus the combination comprising, a stretch of railway track over which trafiic moves in both directions and including a passing siding,a two-wire line circuit responsive to traffic occupying the stretch and the positions of the track switches of said siding and adaptable of being connected to a current source at either end of the stretch for establishing the direction which trafiic is to move over the stretch, two leaving signals one at each end of said siding to govern trafiic entering the stretch from the siding, two control relays, a repeater relay efiective when picked up to open said line circuit at two points one point adjacent each of the two ends of said siding and to connect one of said control relays to one end portion of the line circuit and the other control relay to the other end portion of the line circuit, manually controlled means to govern said repeater relay, and two operating circuits one for each of said leaving signals and selectively controlled by said manually controlled means and said control relays.

3. In railway traffic controlling apparatus the combination comprising, a stretch of single track railway including a passing siding and provided with a block signal at each end to govern trailic entering the stretch, a reversible line circuit extending between the two locations of said block signals for selectively controlling said signals and responsive to traffic occupying the stretch, a leaving signal at each end of said siding to govern trafiic entering said stretch from thesiding, two control relays, a repeater relay, said repeater relay provided with contacts interposed in said line circuit to open the line circuit and connect said control relays one to each end of the line circuit when the repeater relay is picked up, two manually controlled relays one for each of said leaving signals, circuit means including contacts of said manually controlled relays to pick up said repeater relay when either one of the manually controlled relays is energized, and a control circuit for each of said leaving signals and including in series a contact of each of said control relays and a contact of the respective manually controlled relay.

4. In railway traflic controlling apparatus the combination comprising, a stretch of single track railway formed into consecutive track circuited sections for a signal system and including a passing siding having a track switch in a particular one of said sections, a leaving signal for said siding to govern traffic entering the stretch from the siding over said track switch, said signal adaptable to display a safe to leave indication and a proceed indication, a line circuit for said signal system and responsive to trailic occupying said stretch, a control relay, a manually controlled relay, means controlled by said manually controlled relay to interpose said control relay in said line circuit to energize the control relay when the stretch is unoccupied, and circuit means governed by said control relay and by said track switch to operate said signal to its safe to leave indication when the control relay is energized and the switch is normal and to its proceed indication when the control relay is energized and the switch is reversed.

5. In railway trafiic controlling apparatus the combination comprising, a single track railway .27 using a centralized traffic control system and formed with a block extending between two fully signaled passing sidings, said block'arranged with consecutive track circuited sections, a line circuit for said block extending between said fully signaled sidings and controlled by the track circuit of each sectionand adapted to be connected to a current source at one end or the other by said centralized trafllc control system to establish the direction of'traffic over said block, another siding having a track switch in the block intermediate saidtwo fully signaled sidings and provided with a leaving signal to govern trailic entering said block over saidtrack switch, two control relays, another relay energized by a pickup circuit which is governed by said centralized trafilc control system and said other relay operative when energized to open said line circuit at a point adjacent said other passing siding and to connect said two control relays one to each end portion of the line circuit to energize the control relays when the block to each side or" said other siding is unoccupied, a stick circuit including a contact controlled by said switch and closed only when the switch is normal to retain said other relay energized, and a control circuit including in series a front contact of each of said control relays for governing said leaving signal.

6. In railway trafiic controlling apparatus the combination comprising a single track railway using a centralized traflic control system and formed with a block extending between opposing block signal locations, said block arranged with consecutive track circuited sections and provided with two intermediate signal locations, a line circuit extending between said block signal locations but sectionalized at each said intermediate signal location, said line circuit controlled by the track circuit of each said section and adapted to be connected to a current source at one end or the other by said centralized trafiic control system to establish the direction of traffic over the block, a passing siding located between said intermediate signal locations and provided with a leaving signal at each end to govern trafiic entering the block from the siding, two control relays, two code controlled relays on for each said leaving signal and governed by said centralized traffic control system, means controlled by each code controlled relay when energized to open said line circuit at two points corresponding to each end of said siding and to connect said control relays one to each end portion of the line circuit to energize the control relays when said block to each side of said siding is unoccupied, and two signal control circuits one for each leaving signal and each signal control circuit including in series a front'contact of each of said control relays and a front contact of the respective code controlled relay.

7. In railway trafiic controlling apparatus the combination comprising, a single track railway using a centralized trafiic control system and formed with a block extending between opposing block signal locations and provided with twointermediate signal locations, said block arranged with consecutive track circuited sections, a reversible line circuit for said block arranged with three sections having their adjacent ends at said intermediate signal locations and adapted to be controlled in tandem by said centralized trafiic control system to establish the direction of traffic over the block, a passing siding located between said intermediate signal locations, a leaving signal at each end of said siding to govern traflic entering said block from the siding, a circuit network controlled by the positions of said leaving signals and the track switches of said siding interposed in said line circuit, two control relays, two code controlled relays one for each said leaving signal and governed by said centralized traffic control system, a repeater relay energized over a front contact of either one of said code controlled relays, said repeater relay provided with two contact members which are interposed in said line circuit one to each side of said circuit network, each said contact member operative to open the line circuit and connect a respective one of the control relays to the line circuit when said repeater relay is energized, and two signal control cricuits one: for each said leaving signals and each said signal control circuit including in series a front contact of each said control relays and a front contact of the respective code controlled relay.

8. In railway traflic controlling apparatus the combination comprising, a single track railway using a centralized trafiic control system and formed with a block extending between opposing block signal locations, said block arranged with consecutive track circuited sections, a line circuit for said block extending between said block signal locations and controlled by the track circuit of each of said sections and adapted to be connected to a current source at one end or the other by said centralized traflic control system to establish the direction of traflic through said block, a track switch in said block intermediate said block signal locations and provided with a leaving signal to govern ti'aflic entering the block over said track switch, two control relays, another relay energized by a pick-up circuit which is governed by said centralized traflic control system and said other relay effective when energized to open said line circuit at a point adjacent said switch and to connect said two control relays one to one end portion of the line circuit and the other to the other end portion the line circuit to energize each of said control relays by the current source at the corresponding end of the block when the respective track sections are unoccupied, a stick circuit including two alternative paths to retain said other relay energized, one of said paths including a contact controlled by said switch and the other of said paths including in series a front contact of each of said control relays, and a control circuit including in series a front contact each of said controls relays for governing said leaving signal.

JOHN M. PE-LIKAN.

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