US2224401A - Railway traffic controlling apparatus - Google Patents

Description

Dec. 10, 1940. c. H. LAY 2,224,401

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed May 11, 19 4o {LB-S Traffic Controlled INVENTOR fzarler ELag.

HIS ATTORNEY Patented Dec. 10, 1 940 UNITED STATES PATENT orricE RAILWAY TRAFFIC CONTROLLING APPARATUS Application ll Iay 11, 1940, Serial No. 334,609

12 Claims.

My invention relates to railway trafiic controlling apparatus, and more particularly to apparatus for the remote control of railway trafiic governing mechanisms.

-" Control of railway track switches and signals from a remote ofice station over line circuits extending between such office station and the location of the switches and signals is well known and in general use. In such control it is desirable to transmit over a single line circuit two or more different influences each of which eiiects a distinctive function'in order to reduce the number of line circuits extending between the two locations since such locations may be spaced a relatively long distance apart and the provision of independent line circuits for each function is expensive.- When two or more different influences are to be transmitted over a single line ciredit, the current effecting such influences must be time spaced or of different characteristics in order to avoid interference and possible false operation.

Accordingly, a feature of my invention is the provision of novel and improved means, for transmitting over a single two-wire line circuit two or more different currents time spaced to avoid interference.

Another feature of my invention is the provision of novel and improve-d apparatus of 'the type here contemplated-wherewith some currents transmitted over a line circuit continue only long enough to insure that the desired function is initiated and the circuit is automatically conditioned for the transmission of another current 35 and which other current may continue indefinitely until interrupted by some outside change of trafilc or control conditions.

Again; a feature of the invention is the provision of novel and improved means for alter- 40 nately transmitting control and return indication currents over a single two-wire line circuit.-

Another feature of my invention is the provision of novel and improved apparatus for con- 45 trol of a track switch and its related signals from an office station, indication of the position of the track switch and signals at the ofiice station and indication at such ofice station of the .presence of a train in the vicinity of the trackswitch.

The above features, together with other advantages of my invention, I attain by providing two line relays one at a control office station and the other at a field station at which a mechanism to be controlled from the ofiice station is located, connecting such relays at times in series in a two-wire line circuit extending between the two stations and energizing the circuit by current supplied from a source at the field station. The line relay at the oflice station at least is a polarized relay and is selectively responsive to the polarity of the current supplied to this line circuit at the field station for governing an indication means located at the office station for indicating the condition of the controlled mechanism, the polarity of the current supplied to the of the combination of a control relay and a re- 'peater relay. For example, such circuit connection may include a back contact of a neutral control relay and a front contact of a slow release repeater relay with the result such circuit connection is completed and the control current has a duration equal to the slow release period of the repeater relay. The ofiice station current source is capable of supplying current of either normal or "reverse polarity and hence two diii'erout control functions can be effectedby such control current. Subsequent "to the release of the repeater relay, the office station polarized line relay is automatically reconnected to the line circuit for subsequent energization thereof by indication current supplied to the line circuit at the field station.

At the field station thecontrol current is applied over a circuit connection including aback contact of the associated line relay to a controlling polarized -relay whose polar contacts govern operating circuits of the mechanism to be controlled. This field station polarized relay is preferably characterized by its polar contact carrying armature remaining in the position to which it was last moved when the relay is deenergized, and hence it is necessary for the control current to have a duration only suificient to po- :sition the polarized relay in order to effectan operation of the controlled mechanism although the time required to complete such operation may be relatively long and much longer than the duration of the control current. Which-one of two operations of the controlled mechanismis eflected is predetermined by the polarity of the control current since the operating circuits of the controlled mechanism include polar contacts of the controlling polarized relay.

Contacts operated by the controlled mechanism when actuated to the position in agreement with the controlling polarized relay complete a local pick-up circuit for the field station line relay and this line relay on picking up completes at its own front contact a connection by which the field station line relay and current source are transferred from the local pick-up circuit to the line circuit to supply an indication current of a polarity predetermined by the position of the controlled mechanism. The return indication current hence energizes both line relays, and since the relay at the office station is a polarized relay, it is energized at a polarity corresponding to the polarity of the indication current and in turn in agreement with the position of the controlled mechanism.

Another slow acting relay is provided at the field station to delay the completion of the connection of the field station line relay and current source to the line circuit for the return transmission of the indication current, the delay period being predetermined and of suflicient duration to assure that the ofiice station relays, that is, the control relay' and its repeater relay, have had time to disconnect the oince station current source and reconnect the office station polarized line relay to the line circuit.

v I shall describe one form of apparatus embodying my invention and shall then point out the novel features thereof in claims. I

The accompanying drawing is a diagrammatic view showing one form of apparatus embodying my invention when used for the control of a railway track switch and the signals associated therewith from an office station and for indication at the office station of the position of the track switch and the associated signals and the presence of a train in the vicinity of the track switch. It is to be understood of course that I do not wish to limit my invention to the control of a railway track switch' and the associated wayside signals and this one use of apparatus embodying my invention serves to illustrate the many places where the invention is useful.

section and a track relay TR connected across the rails at the other end of the section, the

track circuit being extended to include the turnout rails in the usual and well-known manner.

In accordance with standard practice, four wayside signals R2A, B2B, L2A and LZB are associated with the track switch SW, signals RZA and B2B being mounted on a single mast and governing traiiic moving from the left to the right'as viewed in the drawing, andsignals LZA and LZB governing traffic moving from right to left on tracks IT and 2T, respectively. Additional signals would be preferably provided for governing trafiic approaching the signals associated with track switch SW but such additional signals are not shown since they are not required for a full understanding of my invention and would be in accordance with standard practice. Furthermore, the usual traflic controlled route locking, approach locking and other safety circuits for interconnecting the track switch and the associated signals would be provided but such circuits are also not shown for the sake of simplicity since they form no part of my invention and would be in accordance with standard practice.

The wayside signals R2A, B2B, LZA and LZB may be of any of the well-known types and are shown conventionally.

The track switch SW is operated by a power switch machine SM. The type of switch machine is immaterial', and is shown by the symbol commonly used to indicate a power switch machine. It is sufiicient for the instant application to point out that switch machine SM would preferably include a reversible electric motor (not shown) which is operatively connected to the track switch by a connection indicated by a dotted line ,4, and which motor when supplied with current over a circuit including wire 5 is operated as required to move the track switch to its normal position, that is, the position shown in the drawing, and when supplied with current over a circuit including wire 6, is operated as required to move the track switch to its reverse position, that is, the position opposite that shown in the drawing.

In addition to the usual trafiic controlled circuits referred to hereinbefore for controlling the track switch and the related signals, the control of the switch machine SM and the wayside signals is effected from an ofiice station such as a dispatchers office DS through the'medium of apparatus located partly at the ofiice station DS and partly at a field station FS located adjacent the track switch and which apparatus embodies my invention. Each station DS and FS is provided with a suitable source of current such as a battery, a battery I being located at station DS and a battery 8 being located at station FS. That current of either normal or reverse polarity may be available, the batteries 1 and 8 are preferably of the type provided with a positive terminal BI, a negative terminal NI and a mid or common terminal C. The voltages of the two half portions'of each battery would be alike and the two batteries I and 8 would be preferably of the same voltage.

Referring first to the apparatus at the field station FS, a controlling polarized relay WR is provided for governing the operating circuits of the switch machine SM, the arrangement being such that when relay WR is energized by current of normal polarity and its normal polar converse operating circuit is formed from terminal BI over front contact I0 of relay TR, reverse polar contact II of relay WR, wire 6, motor of switch machine SM and wire l2 to battery terminal NI, and the switch machine is operated as required to move the track switch to its reverse position. The polarized relay WR is preferably of the type whose polar contact carrying armatact 9 is closed, current is supplied to a normal ture remains in the position to which it was last moved when the relay is deenergized. Thus with relay WR energized for a period sufficient to close either polar contact .9 or II, the corresponding operation .of switch machine SM is .accomplished although relay WR may become deenergized before the operation of the switch machine .is fully completed.

Before proceeding further with the description, it should be pointed out that certain contact carrying fingers of the relays are shown remote from the windings of the relays in order to simplify the drawing. In each such case the contact finger is identified by the reference charac- .ter of the relay and is shown in the position corresponding to the normal position of the relay.

The apparatus at the field station FS includes another traiiic governing means in the form of four signal control relays, one for each of the four signals, and which signal control relays are identified by the reference character H plus a prefix corresponding to the reference character of the associated signal. The operating circuits of each signal are controlled by the respective signal control relay. These signal operating circuits would be in accordance with usual practice and are here shown only to the extent required for a full understanding of my invention. As shown, the signal operating circuits are the same for each signal and hence a description of the circuits for one signal will suffice for an understanding of all. Referring to signal R2A, when its signal control relay RZAH is deenergized and released closing back contact. 3 an operating circuit easily traced is completed which causes signal RZA to be operated to a stop position, and when relay RZAH is energized closing front contact M an easily traced circuit is completed by which signal RZA is operated to a proceed position.

A controlling polarized relay SR similar to polarized relay WR is provided at the field station for governing the signal control relays. When polarized relay SR is energized at normal polarity to close neutral front contact. l5 and normal polar contact l5 and the track switch SW occupies its normal position, a circuit is formed from terminal Bi of battery 8 over front contact I! of track relay TR, front contact 15 and normal polar contact [5 of relay SR, contact 18 of a switch circuit controller connected to the track switch es indicated by a dotted line and closed at the normal position of the track switch, winding of relay RZAI-I, a traffic controlled contact [9 and to terminal 0 of battery 8, and relay REAH is energized and picked up to cause signal RZA to be operated to its proceed position. If track switch SW is set at its reverse position moving contact l8 oi the switch circuit controller to the position indicated by the dotted lines, then the circuit above traced is completed through the winding of signal control relay RZBH and traflic controlled contact l9 to battery terminal C, and relay RZBH is energized and picked up to cause signal RZB to be operated to its proceed position. When the track switch SW is set at its normal position and relay SR is energized at reverse polarity to close reverse polar contact 26!, a circuit can be traced from battery terminal Bl over front contact i! of relay TR, front contact l5 and reverse polar contact 29 of relay SR, contact 2! of the switch circuit controller and closed at the normalposition of the switch, Winding of signal control relay LZAH, a trafiic controlled contact 2 and to battery terminal C, and relay MAI-Iv is energized and picked up causing signal LEA to loe operated to its proceed position. In the event track switch SW is set at its reverse position to cause contact 2| of the switch circuit controller to occupy the .dotted line position the last traced circuit is completed over winding of signal control relay L2BI-I and traffic controlled contact 2 to battery terminal 0, and relay LZB-H is energized and'picked up causing signal .LZB to .be operated to its proceed. position. It follows that when the controlling polarized relay SR is energized at normal polarity,signal control relay RZAH .or RZBH is selected according to the position of the track switch and the respective right signal REA or R23 is operated to a proceed position, and when relay SR is energized at reverse polarity the signal control relay LZAH or LZBH is selected according to the position of the track switch and the respective left signal L2A or LEB is operated to a proceed position. The manner of energizing the controlling polarized relays WR and SR by control currents transmitted from the oiiice station DS will be described hereinafter.

Referring to the apparatus at the ofiice station DS, a switch lever LI and a signal lever L2 are mounted for convenient manual operation. The levers LI and L2 may or may not be interlocked and preferably they are levers of a control machine Without mechanical locking or electric lever looks. The switch lever Lil is operable either to a left-hand or normal position N or to a righthand or reverse position R for actuating four circuit controlling contacts 22, 2.3, 24 and 25. circuit controlling contacts are illustrated in the usual conventional manner with the letter N or R placed thereon to designate the position of lever Ll at which the contact closed. Thus the letter N at contact 22 designates that contact 22 is closed :at the normal position of lever Ll.

The signal lever L2 is normally positioned at a center or normal position'N as illustrated in the drawing and is operable either to a left-hand LT or to a right-hand RT position for operating five circuit con-trolling contacts 26, 21, 2.8, 29 and. 333

and whichcircuit controlling contacts are also shown conventionally and provided with the letter N, RT or LT to designate the position of signal lever L2 at which the contact is closed.

A normal switch indication lamp NL, a reverse switch indication lamp RLand a track occupancy lamp OS are disposed adjacent the switch lever Ll and are controlled by a polarized line relay l R. When relay !R is energized at normal polarity to close front neutral contact 3! and normal polar contact 32 the lamps NL and OS are illuminated by current supplied from terminal Bl of battery 1 over front contact 3! of relay IR, filament of lamp OS and wire 33 to terminal C of battery I for lamp OS, and over front contact 3| and normal polar contact 32 of relay IR, filament of lamp NL and wire 33 to terminal 0 for lamp NL. When relay IR is energized at reverse polarity to close front contact 3| andreverse polar contact 34, the lamp OS is illuminated as before and lamp RL is illuminated by current supplied over the circuit completed at reverse polar contact-34 as will be apparent from an inspection of the drawing. Two signal indication lamps LS and RS are disposed adjacent signal lever L2 and controlled by a polarized line relay is, the arrangement being such that when relay IS is energized at normal polarity to close front neutral contact 35 and normal polar contact 36, a simple circuit is completed for lamp RS and when relay l'S is energized at reverse polarity closing front contact 35 and reverse polar con-' tact 31, a simple circuit is completed for lamp LS.

A two-wire line circuit including a line wire WI and a common return line wire CL extending between ofiice station DS and field station FS is provided for the transmission of control current from the office station to the field station for energizing the switch controlling polarized relay WR in accordance with the position of switch lever LI and for the return transmission of indication current for the control of polarized line relay IR in accordance with the position of the track switch and the occupancy of the track section TS. In like manner, a two-wire line circuit including a line wire W2 and the common return line wire CL is provided for the transmission of control current from the office station to the field station for energizing the signal controlling polarized relay SR according to the position of signal lever L2 and for the return transmission of indication current for controlling polarized line relay IS in accordance with the position of the signals associated with switch SW. The common return wire CL is connected to the common terminal C of both batteries 1 and 8 as will be readily apparent from an inspection of the drawing and serves as one side of each of the two line circuits.

Polarized line relay IR is at times connected to the line circuit including line wire WI in series with a line relay 6R at the field station FS and when thus conditioned the line circuit permits the transmission of indication current from the field station to the oflfice station, such indication current energizing relay IR at either normal or reverse polarity to govern the indication lamps NL, RL and OS as explained hereinbeiore. The connection of relay IR to line wire WI is controlled by a neutral control relay 3B and a slow release repeater relay 4R, this combination of relays 3R and 4R being also used to connect battery I to line wire WI for supplying control current to line circuit WICL. Control of relays 3R and 4R is in turn effected by contacts 24 'and 25 of switch lever LI through the medium of a polar relay 2R. Line relay 6R at the field station governs the connection of the switch controlling polarized'relay WR and the battery 8 to the line circuit WICL. When relay GR is deenergized closing back contact 40, relay WR is connected across the line wires WI and CL for energization of relay WR by control current supplied to the line circuit at the ofiice station DS. When relay GR is picked up to close its own front contact 4| the battery 8 and relay 6R are connected to the line circuit in a manner to be explained when the operation of the apparatus is described, battery 8 supplying indication current of a polarity governed by the position of the track switch.

A slow release slow pick-up relay SR is associated with line relay 6R to delay the connection of battery 8 and line relay 6R to the line circuit WICL, the slow acting period of relay 5R being made great enough to assure sufiicient time for the office station relays to automatically disconnect the ofiice station current source and reconnect the line relay IR to the line .circuit subsequent to the transmission of a control current.

In like fashion the polarized line relay IS associated with signal lever L2 is at times interposed in the line circuit including line wire W2 in series with a line relay 65 at the field station for" conditioning this line circuit for the transmission of indication current from the field station to the oflice station, such indication current energizing relay IS at either normal or reverse polarity to control the indication lamps LS and RS in the manner previously explained. The connection of polarized line relay IS to the-line circuit W2-CL is governed by a neutral control relay 3S and a repeater relay 4S, the combination of relays 3S and 4S being also used to govern the connection of battery I to line circuit WICL for supplying control current to this line circuit. Control of relays 3S and 48 is in turn effected by contacts 28, 29 and 30 of signal lever L2. station governs the connections of the signal controlling polarized relay SR and battery 8 to the line circuit W2CL. When relay GS is released closing back contact 63, the relay SR is connected across the line wires W2 and CL for energization thereof by control current supplied to the line circuit at the office station. When line relay SS is picked up to close its own front contact 80, the battery 8 and relay (is are connected to the line circuit in a manner to shortly appear for supplying indication current to the line circuit. A slow release relay SS is associated with line relay ES to delay the connection of battery 8 and relay ES to the line circuit WZ-CL for a predetermined interval subsequent to the transmission of a control current over this line circuit.

Having pointed out the different relays and apparatus embodying my invention, I shall next describe the operation thereof and in so doing I shall assume that at the start the apparatus at both oilice station DS and field station FS occupies the position illustrated in the drawing. With switch lever LI at its normal position N control relay 3R is retained energized by current supplied from terminal BI of battery 'I over normal lever contact 24, normal polar contact 42 of relay 2R, winding of relay 3R and wire 33 to terminal 0 of battery 'I. Repeater relay 4R is in turnenergized over a simple circuit including front contact 43 or relay 3R. With both relays 3R and 4R picked up to close front contacts 49 and 48, respectively, polarized line relay IR is connected to the line circuit WICL, and since line relay 6R at the field station is normally picked up in a manner to later appear, indication current is supplied to the line circuit from battery 8, the polarity of such indication current being of normal polarity in agreement with the normal position of track switch SW. The circuit for the transmission of this indication current can be traced fromterrhinal BI of battery 8 over contact 44 of the switch circuit controller and closed at the normal position of switch SW, normal polar contact 45 of relay WR, winding of line relay 6R, back contact 46 of relay 5R, front contact 4| of relay 6R, front contact 41 of track relay TR, line wire WI to station DS, front contact 48 of relay 4R, front contact 49 of relay 3R, winding of relay IR, wire 33 to terminal C at office station DS and common return wire CL to terminal C of battery 8 at field station FS. This indication current is of normal polarity and relay IR is energized at normal polarity to close front contact 3| and normal polar contact 32 so that normal switch indication lamp N? is illuminated to indicate the normal position of track switch SW and lamp OS is illuminated to The line relay (is at the field indicate that the track section TS is; unoccupied and, trackrelay TR is. picked up. to. closefront: contact 47.

In the event the operator at oince station DS desires to move the track switch SW to its reverse position, the switch lever LI is moved to its reverse position R. The opening of normal lever contact 2&1 deenergizes control relay SR and that relay is deenergized and released immediately to open front contact 49' and interrupt the line circuit so that both line. relays IR and GR are deenergized and released. With relay 3R released to open front contact 43, the repeater relay R is deenergized but is not released until the end of its slow release period. During the interval relay 3B is released and repeater relay GR. is picked up, a control current is supplied to the line circuit WI-CL to energize the switch controlling polarized relay WR. This circuit can be I traced from. terminal NI of battery I, over reverse lever contact 23', back contact 5.9 of relay IR, back contact 5| of relay 3R, front contact 48 of relay 2R, line wire WI to field station FS, front contact 41 of track relay TR, back contact 40 of relay 6R, winding of relay WR and line wire CL back to terminal C of battery I. This control current is of reverse polarity and relay WR is energized at reverse polarity to close its reverse polar contact II so that switch machine SM is operated as required to move the track switch SW to its reverse position. When repeater relay 4R is released at the end of its slow release period to open front contact 48 the control current is interrupted but relay WR remains at its reverse position closing reverse polar contact I I after the control current ceases due to the characteristics of the relay. When repeater relay 4R is released to close back contact 52, current flows from terminal BI of battery I over reverse lever contact 2-5, lower winding 53 of polar relay 2R and back contact 52 of relay 4R to terminal C of battery I, and polar relay 2R is energized as required to close its reverse polar contact 54. The closing of reverse polar contact 54 of relay 2R completes a circuit for reenergizing relay 3R, the circuit including terminal BI of battery I', lever contact 25. reverse polar contact 54 of relay 2R, winding of relay 3R and wire 33 to terminal C. When relay 3R picks up to close front contact 49 repeater relay AB is reenergized and picked up and with both relays SR and 4R picked up to close front contacts 49 and 18, respectively, the polarized line relay IR is again connected to the line circuit WI-CL.

At the field station, the release of line relay R to close back contact 55 completes a circuit from terminal BI of battery 8 over front contact 56 of track relay TR, back contact 55 of relay ER and winding of relay 5R to terminal C, and

- relay ER is energized and picked up at the end of its slow pick-up period. When relay SR is picked up to close front contact 51, a local pickup circuit for relay SR is prepared so that when track relay SW is operated to its reverse position in agreement with the reverse position of relay WR and contact 58 of the switch circuit controlled is moved to the dotted line position, a pick-up circuit for relay 6R. is completed by which current flows. from terminal C of battery Biover resistor 59, front contact 51 of relay 5R, winding of relay 5R, reverse polar contact BIJ of relay WR, contact 58 of the switch circuit controller and to terminal NI of battery 8, and relay GR is pickedup. Relay 6R on being picked up to open back contact 55 deenergizes relay 5R andrelay 5R isdeenergized and released at: the end of its slow release period. Relay ER.- on picking up to close front contact 4% prepares a connection to the line circuit so that when, relay ER is, released to close back contact 46, relay ER and battery 8 are transferred from the local pick-up circuit to the line circuitWICL for supplying an indication current thereto. The circuit for this indication current involves terminal C of battery 8, line wire CL to terminal C of oifice station DS, wire 33, winding of relay IR, front; contacts A9 and 48 of relays 3R and IR, respectively, line wire WI to station FS, front contact 41 of track relay TR.front contact CI of line relay 8R, back contact 46 of relay 5R, winding of relay 6R, reverse polar contact 60 of relay WR and contact 58 of the switch circuit controller to terminal NI of. battery 8. This return indication current is of reverse polarity and line relay lR at the office stationis energized at reverse polarity causing reverse switch indication lamp RLto be illuminated to indicate the reverse position of the track switch, lamp OS being also illuminated as before to indicate that track section TS is unoccupied and track relay TR is picked up.

It is to be pointed out that repeater relay 4R is provided with a slow release period sufficiently long that operation of the polarized relay WR by the control current is assured. Since the circuit of relay SR is closed when relay SR is released to connect polarized relay WR to the line circuit, the slow pick-up period of relay SR is made sufficiently long to assure that relay WR is operated to its reverse position to open normal polar contact 4'5 before relay ER is picked up to close its front contact 5'! with the result that reenergization of line relay 6R by current suppliedover the normal polar contact 45. of relay WR is avoided and that line relay 6R can be reenergized only when its pickup circuit is completed in. response to the track switch SW being moved to the reverse position in agreement with the reverse position of relay WR. The slow release period of relay 5B is made sufficiently long to assure that when relay GR is picked up and relay BB. is deenergized, the relay SR is not released to close back contact 46 and complete the connection of line relay SR and battery 8 to the line circuit until after the relays 3R and 4B. at. the oflice station have had time to disconnect battery I from the line circuit and reconnect the polarized line relay IR thereto. Line relay 6B. is slightly slow releasing to bridge the interval relay ER is in transit between its front contact 5'! and back contact 46.

To restore the track switch SW to its normal position, switch lever LI is moved back to its normal position N. The opening of reverse lever contact 2 5 causes control relay 3R to be deenergized and immediately released to interrupt the line circuit and cause line relays IR and SE to be deenergized and released. Repeater relay 4R is also deenereized when control relay 3R is released but relay 4R does not release until the end of its slow release period and during the period relay SR is released to close back contact 5| and relay 4R. is picked up to close front contact 48 a control current is supplied to the line circuit for energizing polarized relay WR. This control current flows from terminal BI of battery I over normal lever contact 22, back contact 50 of relay IR, back contact 5! of relay 3R, front contact 48 of relay 4R,line wire W'I, front contact 41 of relay TR, back contact Ml of relay BR, winding or relay WR and common return wire CL to terminal C of battery 1,. and relay WR is, energized at normal polarity to close its normal polar contact 9 and cause switch machine SM to be operated as required to move the track switch to its normal position. Again it is to be noted that the control current has a duration equal to the slow release period of repeater relay 4R but that relay WR remains at its normal position after the control current ceases due to the characteristic of the relay. The closing of normal contact 24 of lever LI supplies current topolar relay 2R from terminal BI of battery I over lever contact 24, top winding 62 of relay 2R and back contact 52 of relay 4R to terminal C of battery I, and relay 2R is energized at normal polarity to close its normal pole contact 42 so that the relay 3R is reenergized over the circuit including lever contact 24 and normal polar contact 42. Relay 3R on picking up reenergizes repeater relay 4R and that relay on picking up to close contact 48 completes the connection of line relay IR to the line circuit. At the field station the release of line relay 6R to close back contact 55 energizing relay 5R which relay on picking up to close front contact 5! prepares the pick-up circuit for line relay 6R so that when the track switch is operated to its normal position in agreement with the normal position of relay WR current is supplied to the pick-up circuit of relay 6R from terminal BI of battery 8 over contact 44 of the switch circuit controller, normal polar contact 45 of relay WR, winding of relay 6R, front contact 51 of relay 5R, resistor 59 and to terminal C of battery 8. When line relay GR. is picked up over this pick-up circuit to open back contact 55, relay SR is deenergized and releases at the end of its slow release period to complete the connection of battery 8 through line relay 6R. to the line circuit and indication current flows from terminal BI of battery 8 over contact 44 of the switch circuit controller and the circuit previously traced by which line relay IR at the office station is energized at normal polarity in series with relay 6R. Energization of relay IR at normal polarity causes the display of the normal switch indication lamp NL and track occupancy indication lamp OS in the manner described hereinbefore.

It should be observed that in the event switch lever LI is moved to its reverse position and control current is transmitted from the office station for energizing controlling relay WR at reverse polarity and the switch machine fails to move the track switch to the corresponding reverse position, the operation of the switch lever LI back to its normal position will cause a transmission of control current of normal polarity to energize relay WR at its normal polarity and bring this relay into agreement with the position of the track switch since relays 3R and 4R are reenergized subsequent to the transmission of the control current independent of the apparatus at the field station.

Again, it should be observed,'that when a train occupies track section TS toshunt track relay TR the line circuit'is opened at front contact 41 of relay TR with the result that line relay I R and line relay 6R are both deenergized and that when line relay IR is deenergized both lamps NL and OS are extinguished to indicate that the track section TS is occupied and that the track switch cannot be controlled at the oflice station. When the train vacates section TS and relay TR is picked up to close front contacts 41 and 5B, relay SR is picked up to complete the local pick-up circuit for relay GR and relay 6R on picking up closes front contact 4| to prepare the connection to 'the line circuit and opens back contact 55 to cause relay 5R'to be released, so that when back contact 46 of relay SR is again closed the line circuit is again reestablished for the transmission of the return indication current. 5 From the foregoing description of the operation of the apparatus associated with switch lever LI, it is clear that with lever LI at either its normal or reverse position relays 3R and 4R are picked I up and line relays IR and GR are interposed in 10 series in the line circuit for the transmission of indication current from the field station, the polarity of the current being predetermined according to the position of the track switch and the transmission of which indication current will 15 continue indefinitely. When lever LI is moved from one position to the other relays 3R and 4R are operated sequentially and. control current is transmitted during the release period of repeater relay 4R to bring about energization of control- 20 ling relay WR at a polarity predetermined according to the position of switch lever LI. When switch SW is operated to the position in agreement with controlling relay WR, a local pick-up r circuit for line relay SR is completed and when relay GR is picked up it reestablishes a line circuit for the transmission of a return indication current. It is also clear that slow acting relay 5R delays the reestablishing of the line circuit for the transmission of the return indication cur- 30 rent for a predetermined period which is great enough to assure that the relays 3R and 4R have time to release sequentially and then to be reenergized and reconnect line relay IR to the line circuit.

In taking up the operation of the apparatus associated with signal lever L2 for controlling the wayside signals, it is to be noted that since signal lever L2 normally occupies a center position N for which all signals are at a stop position, the con- 40 trol of relay 3S and its repeater relay 43 is preferably modified from that provided for relay 3R and its repeater relay 4R associated with switch lever LI, to the extent that relays 3S and 48 are retained energized until the transmitted control 45 current completes its designated function at the field station at which time the line circuit is preferably interrupted by operation of the relays at the field station and relays 4S and 38 are then caused to function to disconnect the current 50 source at the office station from the associated line circuit and to connect the line relay IS to the line circuit. Also at the field station, the slow release relay 5S is normally energized with the result that the line relay GS is normally deener- 55 gized to connect the controlling polarized relay SR to the line circuit and to disconnect the current source 8 from the line circuit. When signal lever L2 is at its normal center position N to close normal contact 30, a simple circuit is completed 60 for repeater relay 4S and relay 48 is picked up. At the field station slow release relay 53 is normally energized by current supplied over a circuit including terminal BI of battery 8, back contacts 64, as, as, 61 and as of relays RZAH, RZBH, L2AH, 65 L2BH and 68, respectively, winding of relay 5S and terminal C.

In the event it is desired to operate either one of the right signals R2A or R23 to permit a train to move over the track switch, signal lever 70 L2 is moved to its right-hand position RT. When lever contact 30 is opened, the repeater relay 48 is deenergized, but relay 45 is retained picked up for a period due to its slow release characteristic. The closing of lever contact 28 at the 75 RT position completes. a circuit over which a signal control current flows from terminal BI of battery I, through lever contact 28, winding. of relay 38, front contact 69 of repeater relay 4S, line wire W2, back contact 63 of relay 6S, winding of polarized relay SR and common return wire CL to terminal C of battery 1. This control current is effective to energize and pick up relay 3S and to energize relay SR at normal polarity. The picking up of relay 33 to close front contact 10 completes a second circuit by which the repeater relay is is retained energized as long as the control current continues. The energizing of relay SR at normal polarity to close front contact l5 and normal polar contact Ill completes the previously traced circuit for either relay RZAH or RZBH depending upon the position of the track switch SW and either signal REA or RZB is operated to a proceed position.

-When signal control relay RZAH or RZBH is picked up to open either back contact 6t or the slow release relay 58 is deenergized and released at the end of its slow release period. During the interval that either relay RZAH or RZBH is picked up to close either front contact H or T2 and relay 5S is picked up to close its front contact M, a pick-up circuit for line relay GS is completed over which current flows from terminal Bl of battery 8, through either front contact ll or 12, normal polar contact it of relay SR, winding of relay 66, front contact 14 of relay 5S, resistor 15 and to terminal C of battery 8. With line relay 6S picked up due to the above traced pick-up circuit to open back con- .tact 53 the line circuit is interrupted and the control current ceases. This causes relay at the office station and relay SR at the field station to be deenergized and immediately released, the normal polar contact of relay SR remaining closed however, due to the characteristic of relay SR. The closing of front contact 16 of relay 6S completes a shunt path around front contact l5 of relay SR so that the circuit of the signal control relay RBAH or RZBH is still com plete after relay SR is deenergized. At the oflice station, the opening of front contact ill of relay 3S deenergizes repeater relay 4S and relay 4S releases at the end of its slow release period to close back contact H and complete a connection by which line relay lS is connected to the line circuit. The slow release period of repeater relay is need be only long enough to bridge the interval between the opening of lever contact 30 and the closing of front contact 18 of relay 3S subsequent to the movement of the signal lever. At the field station, relay SS is provided with a slow release period somewhat greater than the slow release period of relay ts at the office station, so that when relay SS is released to close back contact 18 and transfer battery 8 and line relay ES to the line circuit battery I has been disconnected from the line circuit and an inclication current flows from terminal Bl of battery 8 over either front contact H or 12 of re- .lay REAH or REBH, normal polar contact 13 of relay SR, winding of relay ES, back contact l8 of relay 53, front contact 86 of line relay 6S, line wire W2, back contact ll of relay 48, Winding of relay l S, lever contact 26, wire 33 to terminal C at the office station and line wire CL to terminal C of battery 8 at the field station; Line relay SS is now retained energized in series with the line relay IS by the indication current, relay IS being energized at normal polarity to cause indication lamp RS to be illuminated to indicatethat relay RQAH' or RZBI-I has been picked. up to. operate the respective right signal R2-Aoit R23 to a proceed position.

It follows that a control. current is supplied from battery II at the oifice station to the line circuit. W2CL just. long enough to cause operation of polarized relay SR and the picking up of the signal control relay. When the selected signal control relay is'picked up a local pick-up circuit'is formed. for line relay 6S during the slow release period of. the relay 5S and relay 6S on picking up opens the line. circuit and interrupts; the control current Subsequent to the interruption of the control current, control relay 3S and repeater relay 48 are operated to disconnect the battery 1 of the office station from the line circuit and to connect the line relay IS thereto. When slow acting relay 5S is released battery 8" and line relay 6S are transferred from the local pick-up circuit to the line circuit and an indication current is supplied to the line circuit which energizes relays 6S and IS in series and causes a corresponding indication lamp to be illuminated, and which indication current may continue until the circuit is changed either by a movement of the signal lever or by trafiic conditions in the vicinity of the track switch. In the event a train moves past signal R2A or RZB into track section TS to shunt track relay TR, the release of relay TR toopen front contact l 'l deenergizes the selected signal control relay REAl-I or RZBH and that relay upon releasing causes the associated, signal to be operated to its stop position. Also the line circuit is interrupted at either front contact H or 12 of the signal control relay and the transmission of the indication current is discontinued with the result that both line relays IS and 63 are deenergized and released, the release of relay IS causing lamp RS to be extinguished to indicate the stop position of the signal. Release of line relay as at the field station to close back contact 68 completes the circuit for relay 5S and that relay is picked up withthe result that when the train vacates track section TS and track relay TR is re-energized, the signalcontrol relay RZAH or REBH cannot be again energized until a new control current for energizing relay SR to close its front contact 15 is transmitted from the of fice; station.

i In the event signal; lever L2 is restored to its normal: position N subsequent to the extinguishing of the indication lamp RS, the closing of lever: contact 30- reenergizes repeater relay 48 after which a new signal control current may be transmitted for energizing relay SR by moving lever L2 again to its RT position.

The operation of the apparatus for the control of a left signal LZA or L2B in response to a movement of signal lever L2 to its LT position is similar to that'described in detail in connection with operation of lever L2 to its RT position for controlling signal REA or R213 and the description neednot be repeated except to point out that when lever L2 is moved to its LT position contact 29- connects the line circuit W2CL to terminal N1 of battery 1 and the. control current is of reverse polarity so that relay SR is energized at reverse "polarity to select either signal. control relay L2AH- or LZBI-I. Also with relay SR energized at reverse polarity the closing either front contact 8! or B2 of relay LZAH or L2-BH,. connects terminal N l of battery 8 to the pick-up circuit of line relay 6S so that when relay SS is released to transfer battery 8 and line relay ES to the line circuit the return indi cation current is of reverse polarity with the result that relay IS is energized at reverse polarity to cause lamp LS to be illuminated to indicate that a left signal has been operated to a pro-'- ceed position.

Although I have herein shown and described only one form of railway trafiic controlling apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims'without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In railway trafiic controlling apparatus for use with a two-wire line circuit extending between a first and a second station and a current source at each station for the exchange of control and indication influence between the two stations, the combination comprising, a line relay at each station, a manually operable lever at said first station, a controlling relay at said second station to govern the operation of a controlled mechanism, means including a contact governed by said lever and a back contact of the line relay at said second station to connect the current source of said first station and said controlling relay to the line circuit for transmitting a control influence from the first to the second station to cause operation of said controlled mechanism, automatic means initiated by movement of the lever to terminate said control influence and subsequently connect the line relay at the first station to the line circuit, a local pick-up circuit including a contact governed by said controlled mechanism to connect the line relay of the second station to the current source of that station to pick up that line relay, and circuit means including a front contact of the line relay at the second station and a contact governed by said controlled mechanism to connect the current source and the line relay at the second station to the line circuit in series with the line relay at the first station for transmitting an indication influence from the second to the first station.

2. In railway traflic controlling apparatus for use with a two-wire line circuit extending between a first and a second station and a current source at each station for the exchange of control and indication influence between the two stations, the combination comprising, a line relay at each station, a manually operable lever at said first station, a controlling relay at said second station to govern the operation of a controlled mechanism, means including a contact governed by said lever and a back contact of the line relay at said second station to connect the current source of said first station and said controlling relay to the line circuit for transmitting a control influence from the first to the second station to cause operation of said controlled mechanism, automatic means initiated by movement of the lever to terminate said control influence and subsequently connect the line relay at the first station to the line circuit, a local pick-up circuit including a contact governed by said controlled mechanism to connect the line relay of the second station to the current source of that station to pick up that line relay, circuit means including a front contact of the line relay at the second station and a contact governed by said controlled mechanism to connect the current source and the line relay at the second station to the line circuit in series with the line relay at the first station for transmitting an indication infiuence'from the second to the first station, and a slow release relay at the second station energized over a back contact of the line relay at the second station and having a back contact interposed in said circuit means to delay for a predetermined period the transmission of such indication influence.

3. In railway trafiic controlling apparatus for use with a two-wire line circuit extending between a first and a second station and a current source at each station for the exchange of control and indication influences between the two stations, the combination comprising, a line relay at each station, a manually operable lever at said first station, a controlling relay at said second station to govern the operation of a controlled mechanism, an indicator controlled over a contact of the line relay at said first station, a slow release repeater relay controlled by a contact of said lever; means including another contact of said lever, a front contact of said repeater relay and a back contact of the line relay at the second station to connect the current source at said first station and said controlling relay to the line circuit for transmitting a control influence from the first to the second station to cause operation of said controlled mechanism; automatic means including contacts of said repeater relay to disconnect the current source of the first station from the line-circuit and to connect the line relay of that station thereto, a slow release relay at said second station energized over a back contact of the line relay at that station, a local pick-up circuit including a contact governed by said controlled mechanism and a front contact of said slow release relay to connect the line relay at the second station to the current source of that station to pick up that line relay; and means including a front contact of the line relay at the second station, a back contact of the slow release relay at that station and a contact governed by said controlled mechanism to connect the current source and line relay at the second station to the line circuit in series with the line relay at the first station for transmitting an indication influence from the second to the first station to effect a control of said indicator.

4. In railway traffic controlling apparatus for use with a two-wire line circuit extending between a first and a second station and a current source at each station for the exchange of control and indication influences between the two stations, the combination comprising, a line relay at each station,, a manually operable lever at said first station, a controlling relay at said second station to govern the operation of a controlled mechanism, an indicator governed over a contact of the line relay at the first station, a slow release repeater relay at the first station normally energized over a contact governed by said lever; means including another contact governed by said lever, a front contact of said repeater relay and a back contact of the line relay at the second station to connect the first station current source and said controlling relay to the line circuit to energize the controlling relay by control current transmitted from the first station during the slow release period of said repeater relay to effect an operation of said controlled mechanism; automatic means controlled over a back contact of the repeater relay to connect the first station line relay to the line circuit, another slow release relay at the second station energized over a back contact of the line relay at that station, a local pick-up circuit including a contact governed by said controlled mechanism and a front contact of said other slow release relay to energize the second .station line relay from the second station current source; and means including said contact governed by the controlled mechanism, a back contact of said other slow release relay and a. front contact of the second station line relay to transfer the second station line relay and current source to the line circuit to energize said two line relays in series by indication current transmitted from the second station to effect a control of said indicator.

5. In railway trafiic controlling apparatus for use with a two-wire line circuit extending -be tween a first and a second station and a current source at each station for the exchange of control and indication influences between the two stations, the combination comprising, a manually operable lever having a first and a second position located at the first station, a polarized controlling relay at the second station to govern a controlled means to either a first or a second position, indication means having .a first and a second condition located at the first station, a polarized line relay at the first station to govern said indication means, another line relay at the second station, means including either a first or a second position contact of said lever and a back contact of said other line relay to connect the first station current source and said polarized controlling relay to the line circuit to energize said controlling relay at normal or reverse polarity according to the position of the lever to effect a corresponding position of the controlled means, automatic means controlled by said lever effective to disconnect the first station current source from the line circuit and connect said polarized line relay thereto subsequent to a movement 01 the lever, a local pick-up circuit including either a first position contact of said controlled means and a normal polar contact of said controlling relay or a second position contact of the controlled means and a reverse polar contact of the controlling relay to energize said other line relay, and means including a front contact of said other line relay and afirst or a second position contact of said controlled means to connect the second station current source to the line circuit to energize said polarized line relay at normal or reverse polarity according to the position of the controlled means to efiect a corresponding condition of said induction means.

6. In railway traflic controlling apparatus for use with a two-wire line circuit extending between a first and a second station and a current source at each station for the exchange of control and indication influences between the two stations, the combination comprising, a line relay at each station, a manually operable lever at the first station, a normally deenergized controlling relay at the second station, a control relay and a slow release repeater relay at the first station, means including a contact of said lever to energize said control relay and in turn said repeater relay; means including a front contact of said control relay, a front contact of said repeater relay, a front contact 'of the second station line relay and a contact governed by 5 said controlling relay to connect said two .line

relays and the current source at the second station in series in the line circuit for transmit ting an indication influence from the second to the first station and which may continue indefinitely,- means including a back contact of sa-id control relay, a vfront contact of said repeater relay and aback contact of the second station line relay to connect the first station current source and said controlling relay to the line circuit for transmitting a control influence from the-first to the second station when the lever is moved and which influence continues for the slow release period of the repeater relay, automatic means controlled over a back contact of the repeater relay to reenergize said control relay, and .a pick-up circuit including a contact governed by said controlling relay in response to the control influence to connect the second station line relay to the current source at that station to pick up that line relay and reestablish the line circuit with the two line relays in series for transmitting a new indication influence from the second to the first station.

7 In railway traific controlling apparatus jor use with a two-wire line circuit extending be{ tween a first and a second station and 1a current source at each station for the exchange of control and indication influences between the two stations, the combination comprising, a line relay at each station, a manually operable lever at the first station, a normally deenergized controlling relay at the second station,- a control relay and a slow release repeater relay at the first station, means including a contact of said lever to energize said control relay and in turn said repeater relay; means including a front contact of said control relay, a front contact of said repeater relay, a front contact of the second station line relay and a contact governed by said controlling relay to connect said two line relays and thecurrent source at the second sta tion in series in the line circuit for transmitting an indication influence from the second to the first station and which may continue indefinite- 1y; means including a back contact of said control relay, a front contact of said repeater relay and a back contact of the second station line relay to connect the first station current source and. said controlling relay to the line circuit for transmitting a control influence from the first to the second station when the lever is moved and which influence continues for the slow release period of the repeater relay, automatic means controlled over a back contact of the repeater relay to reenergize said control relay, a pick-up circuit includinga contact governed by said controlling relay in response to the control influence to connect the second station line relay to the current source at that station to pick up that line relay and reestablish the line circuit with the two line relays in series for transmitting a new indication influence from the second to the first station, and a slow re-= lease relay at the second station energized over a back contact of the line :relay at the same station and having a back contact interposed in the connection of the second station current source to the line circuit to delay the transmission of the indication influence .for a period.-

8. In railway traflic controlling apparatus foruse with a two-wire li-ne circuit extending be-. tween an ofiioe station :and a track switch for governing the track switch .to its normal and, reverse positions in agreement with the normal and reverse positions of .a switchlever at the oifice station and for governing a normal and a reverse indicator at the oilice station in agreement with the position of the track switch, the combination comprising, a polarized line relay at the office station for controlling said indicators, a polarized switch controlling relay at the switch, a control relay and a slow release repeater relay at the ofiice station, means including either a normal or a reverse lever contact to energize said control relay and said repeater relay, another line relay at said switch, means including a back contact of said other line relay to connect said polarized controlling relay to said line circuit, means including either 'a normal or a reverse lever contact together with a back contact of said control relay and a front contact of said repeater relay to supply control current of normal or reverse polarity to the line circuit to energize said controlling relay according to the position of the lever to effect a corresponding position of the switch, means including a back contact of said repeater relay to reenergize said control relay and in turn the repeater relay, means including a front contact of the control relay and a front contact of the repeater relay to connect said polarized line relay to the line circuit, a pickup circuit including a normal position switch contact and a normal polar contact of the controlling relay or a reverse position switch contact and a reverse polar contact of the controlling relay to pick up said other line relay, and circuit means including a front contact of said other line relay and said switch contacts to supply indication current of normal or reverse polarity to the. line circuit to energize said polarized line relay to control the corresponding indicator.

9. In railway trafiic controlling apparatus for use with a two-wire line circuit extending between an oflice station and a track switch for governing the track switch to its normal and reverse positions in agreement with the normal and reverse positions of a switch lever at the oflice station and for governing a normal and a reverse indicator at the office station in agreement with the position of the track switch, the combination comprising, a polarized line relay at the ofiice station for controlling said indicators, another line relay at the track switch, a polarized switch controlling relay connected to said line circuit over a back contact of said other, line relay, a control relay and an associated slow release repeater relay at the ofiice station, means including either a normal or a reverse lever contact to energize said control relay to cause said control relay and its repeater relay to be sequentially released when the lever is moved from one position to the other, means including a normal and a reverse lever contact together with a back contact of said control relay and a front contact of said repeater relay to supply control current of normal or reverse polarity according to the position of the lever to the line circuit to correspondingly energize said switch controlling relay, means including a back contact of the repeater relay to reenergize'said control relay, means including a front contact of said control relay and a front contact of the repeater relay to connect said polarized line relay to the line circuit, another slow release relay energized over a back contact of said other line relay, a local pick-up circuit including either a normal switch contactand a normal polar switch controlling relay contact or a reverse switch contact and a reverse polar. switch controlling relay contact'andcontrolled.

over a front contactof said other slow release relay'to energize said other line relay, means including aback contact of said other slow release totr'ansfersuch pick-up circuit to said line circuit 'to supply indication current of normal or reverse polarity according to the position of the switch to correspondingly energize said polarized line relay. e a

10. In railway trafiic controlling apparatus for use with atwo-wire line circuit extending between an ofii'cestation and-a track section for controlling aright and a left signal at the track section from a signallever at the oflice station and indicating at such lever the condition of the signals, the combination comprising, a polarized line relay at the oflice station for selectively governing a right and a left signal indicator, another line relay at the track section, a polarized signal controlling relay for selectively governing said signals and connected to said line circuit over a back contact of said other line relay, a control relay and an associated repeater relay at the ofiice station and said repeater relay energized over either a normal'position contact of said signallever or a front contact of said control relay, means including either a right or a left position contact of said lever to supply current of normal or reverse polarity to the line circuit through the winding of said control relay to energize the control relay and correspondingly energize said signal controlling relay, a slow release relay ener'gized over a back contact of said other line relay, a pick-up circuit including either a normal or a reverse polar contact of said signal controlling relay and a front contact of said slow release relay to pick up said other line relay to interrupt the control current and cause the .sequential release of the control and repeater relays, means including aback contact of the repeater relay to connect said polarized line relay to the line circuit, and means including a back contact of said slow release relay and a front contact of said other line relay to transfer said pick-up circuit to the line circuit to supply indication current of normal or reverse polarity according to the position of the signal controlling relay to'correspondingly energize said polarized line relay.

11-. 'In railway traffic controlling apparatus, the combination comprising, a two-wire line circuit extending between an office station and a field station, a currentsource at each station, a control lever at the ofiice station operable to a first and a secondposition, indication means at the office station having afirst and a second condition, a trafiic controlling mechanism at the field station having a first and a second position, a polarized controlling relay at the field station for selectively governing the positions of said mechaanism, a polarized line relay at the office station for selectively governing the conditions of said indication means, another line relay at said field station, a slow release relay at the office station, means including a contact governed by said lever and closed inresponse to either position of the lever to energize said slow release relay and operative to deenergize that relay and subsequently reenergize therelay when the lever is moved from one position to the other, means including a front contact of said slow release relay and a back contact of said other line relay to connect the office station current source and said controllingpolarized relay to said-line circuit to supply ourrent of normal or reverse polarity to said controlling relay according to the position of the lever during the slow release period of said slow release relay for governing said mechanism, a pick-up circuit including a contact governed by said mechanism to pick up said other line relay, and means including a front contact of said other line relay and a front contact of said slow release relay to connect said two line relays and said field station current source in series in .said line circuit to supply current of either normal or reverse polarity according to the position of the mechanism to energize said polarized line relay for governing the indication means.

12. In railway traific controlling apparatus, the combination comprising, a two-Wire line circuit extending between an ofice station and a field station, a current source at each station, a control lever at the oflice station operable to a first and a second position, indication means at the office station having a first and a second condition, a trafiic controlling mechanism at the station having a first and a second position, a polarized controlling relay at the field station for selectively governing the positions of said mechanism, a polarized line relay at the ofiice station for selectively governing the conditions of said indicating means, another line relay at said field contact and a back contact of said repeater relay to energize said polar relay at normal or,reverse polarity, means including a first position lever contact and a normal contact of said polar relay or a secondposition lever contact and a reverse contact of the polar relay to energize said control relay, means including a front contact of the control relay to energize said repeater relay, means including a back contact of said control relay, a front contact of said repeater relay, a back contact of said other line relay and either a first or a second position lever contact to connect said oifice station current source and said controlling polarized relay to said line circuit to energize that polarized relay at a polarity predetermined by the position of the lever, a pickup circuit including either a first position contact of said mechanism and a normal polar contact of said controlling relay or a second position contact of saidlmechanism and a reverse polar contact of said controlling relay to pick up saidother line relay, and means including a front contact of said control relay, a front contact of said other line relay and either a first or a second position contact of said mechanism to connect said two line relays and the field station current source in series to said line circuit to energize said polarized line relay at a polarity predetermined by the position of said mechanism.

CHARLES H. LAY.

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