US2170129A - Centralized traffic control system for railroads - Google Patents

Description

Aug. 22, 1939.

D. F. DE LONG CENTRALIZED TRAFFIC CONTROL SYSTEM FOR RAILROADS 5 Sheets-Shee t 1 Filed Aug.

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ATTORNEY D. F. DE LONG Aug. 22, 1939.

CENTRALIZED TRAFFIC CONTROL SYSTEM FOR RAILROADS Filed Aug. 7, 1930 5 Sheets-Sheet 2 BY Ego/2Z6 7 I! ream m om m mmo v5 25 go uSu @nu lllllllllllllllIl-Illlllllllll 5 Sheets-Sheet 3 D. F. DE LONG Filed Aug. 7, 1930 BY ltzwgloz CENTRALIZED TRAFFIC CONTROL SYSTEM FOR RAILROADS x269 m wwr Aug. 22, 1939.

u Fiwv 525.30

CONTROL SYSTEM FOR RAILROADS Filed Aug. 7, 1930 5 Sheets-Sheet 4 Aug. 22, 1939. D. F. DE LONG CENTRALIZED TRAFFIC arm /l HOW N NE W k ll I I I I UCmH ESNUNFEQEEUU ATTORNEY I Aug. 22, 1939'. D. F. DE LONG 2,170,129

CENTRALIZED TRAFFIC CONTROL SYSTEM FOR mnnoms Filed Aug.. '7, 19:50 5 Sheets-She et 5 4. First way 5econd Way Last Wa'.y Control OFFice Stan 5101M" SFG'tIOH FIG.5..

TYPICAL TABLE OF CODES Code. Call Cbde. Respons ive Relay No. v A .B C 1 Patented Aug. 22, 1939 UNITED STATES PATENT OFFICE CENTRALIZED TRAFFIC CONTROL SYSTEM FOR RAILROADS Darrol F. De Long, Rochester, N. Y., assignor to General Railway Signal Company, Rochester,

Application August 7, 1930, Serial No. 473,529

25 Claims.

This invention relates to centralized traffic con.- trolling systems for railroads, and more particularly pertains to a code type communication system, by means of which a dispatcher or operator may govern, from a conveniently located control office, the operation of a plurality of traflic controlling devices located along a railroad, and is informed of the progress of trains and the operated conditions of such trafiic controlling devices.

It has been found expedient in governing the movements of trains over a railroad, to place the control of such train movements under the supervision o-f an operator stationed at a convenient point along the railroad. In order that this supervision may be the most efiicient, it is desirable that an electric communication system be provided to enable the operator to manually control the signals, switches, derails, and the like located along the railroad, and also to inform the operator as to the progress of trains and such other conditions as may be desirable. In such a system, the various track switches and derails are usually operated by power, under the manual control of the operator, with suitable provisions for approach locking means local thereto preventing their improper and dangerous operation; and the signals governing traflic over the switches are automatically controlled by ad.- joining track circuits in accordance with automatic signalling practice, subject to the control of the operator, who may holdany such signal at stop irrespective of its automatic control, or may allow such signals to clear when the positions of trains are such as to make it safe to do so. The intermediate signals, which are be.- tween those signals at route determining points, are preferably provided only with automatic control governed in accordance with trackway conditions.

The present invention relates more particularly to such a communication system which is employed to enable the operator to condition at will, a function control relay, for each traffic controlling device in the territory under his supervision, in such a way that the signals, switches, derails, and the like may be moved to such positions as the operator may desire, subr ject to the automatic control of the signalling sys- 50 tem associated therewith which prevents their unsafe operation. This function of the system is conveniently termed the transmission of controls.

The communication system, constituting more particularly the subject matter of this invention,

is further utilized to transmit to the operator the position of the various traffic controlling devices, the occupancy of certain track circuits and such other conditions as may be desirable to facilitate in the governing of train movements over the railroad. This function of the system. is conveniently termed the trans-mission of indications.

By way of explanation, and without attempting to define the nature or scope of the invention, it may be stated, that in the communication system of this invention, certain adjacent or associated traffic controlling devices with their related indications are preferably grouped in what may be referred to as a field or way station. All such way stations, throughout the railroad, are connected with the control ofiice by three line wires which are employed to form a stepping circuit and a message circuit.

In the transmission of controls from the control ofiice, for the purpose of operating signals, switches, and the like at a particular way station, a series of stepping impulses are placed upon the stepping circuit extending to all the stations, which causes step-by-step means at thecontrol ofiice and at each of the way stations totake a plurality of steps. During a number of these steps taken by each step-by-step means, a combination of impulses, conveniently termed a code call, which is allotted to that station, is transmitted over the message-circuit extending to all the way stations, but effective selecting response thereto is obtained only at the particular station being called. After such selection of that station, the remaining steps of the cycle are em,- ployed to transmit both the desired new controls and the indications of that station, as then set up, by impulses placed upon the message circuit by suitable control means respectively at the control oflice and that way station.

Indications of the position of switches, signals, and the like and the conditions of certain track circuits, are transmittedto the control office from the several stations one at'a time. A station, having one or more new indications to transmit, initiates the system into operation causing a series of impulses to be placed upon the stepping circuit to operate the step-by-step means at the control office and at each way station. During a certain number of the steps taken by the stepby-ste-p means, a combination of impulses is placed upon the message circuit, at that way station, corresponding to its code call which identifies or registers that station in the control office. After this station selection or registration has taken place, the remaining steps of that cycle of operation are taken during which impulses are placed upon the message circuit in correspondence to the new indications to be transmitted from that station and in correspondence with the controls for that station as then set up in the control office.

If more than one station is ready to send in new indications to the control office, these stations are allowed to register themselves and communicate their indications, one station at a time, in a sequence or order determined by their geographic location.

Since, in accordance with this invention, the transmission of new controls and the registration of each station desiring to send in new indications is accomplished over the message circuit, an important feature of the system of this invention resides in the manner in which only one such station is selected for the transmission of new controls and only one such station having new indications is allowed to register itself in the control ofiice during a particular operating cycle, with only one of these functions occurring during a particular operating cycle of the system.

The communication system of this invention may be said, therefore, to be of the station selective type employing code combinations or code calls for station selection both for the transmission of controls and indications.

Various other characteristic features, functions and advantages of the system of this invention are more conveniently explained and pointed out hereinafter, following the description of one embodiment of the present invention and its mode of operation. Many of these features and advantages will be apparent as the description progresses, and need not be specifically pointed out in detail.

For the purpose of explaining the nature of the invention, there has been shown in the accompanying drawings, one typical embodiment of the invention adapted for controlling the switches and signals at the ends of passing sidings on a single track railroad; but the same principles and functioning of the invention, and the same apparatus and circuits may be employed, or may be adapted by obvious modifications, for the control of switches, signals, derails or other traffic controlling devices for all kinds of track lay-outs, and for the receiving of indications of the positions or conditions of such trafiic controlling devices, track circuit occupancy and such other conditions as may be desirable.

In describing the invention in detail, reference will be made to the accompanying drawings, in which similar parts throughout the several Views are designated by like reference characters provided with distinctive exponents, and in which Figs. 1A and 1B when placed end to end illustrate the apparatus and circuits for the control oifice of a communication system constructed and arranged according to the present invention;

Figs. 2 and 3 illustrate the equipments for two typical way stations of the system, having distinctive code calls for their selection;

Fig. 4 shows the arrangement of the line circuits;

Fig. 5 shows a typical table of code combinations of impulses employed for station selection in the system.

For the purpose of simplifying the illustration and facilitating the explanation, the various parts and circuits constituting the system have been shown diagrammatically andcertain conventional illustrations have been employed, the drawings having been made more with the idea of making it easy to understand the principles and mode of operation of the system, than with the idea of illustrating the specific construction and arrangement of parts that would be employed in practice. Thus, the various relays and their contacts are illustrated in a conventional manner, and symbols are used to indicate connections to the terminals of batteries or other sources of electric current in place of showing all the wiring connections to such terminals.

Considering first the general organization of the system, three line wires are employed in the particular form shown, namely, a stepping line, a message line and a common return line. These line wires extend'from the control office through the several stations, with the stepping line con nected to the common return wire beyond the last way station (see Fig. 4), while the message line is left open-ended at the last station. These line wires are employed to form two separate circuits, with a common return connection (common return line), conveniently termed a stepping circuit and a message circuit.

The stepping line wire includes at each station and at the control office, a polar line relay L (see Fig. 4) and the message line wire includes at each station a back contact of a field control relay FC.

The stepping circuit and the message circuit are both supplied with direct current from sources located at the control ofiice. The field stations do not supply current to the line circuits of the system at any time. This supply of direct current in the control office for energizing the stepping and message circuits may be a storage battery with suitable trickle charge or other charging means, motor generator, or any other suitable source, the voltage required varying with the number of way stations and the length of the line circuits connecting such way stations with the control office.

A source of direct current is required for each field station for energizing the local circuits of g the communication system, and for operating the signals, switches and the like at that station. Storage batteries, maintained charged through rectifiers from a suitable power line, are preferably employed for this purpose in accordance with common practice.

Such sources of electrical energy which supply current to the circuits local to the control oflice and each of the way stations are represented by the use of the conventional battery symbols and indicating connections to the opposite terminals of a battery or other suitable source of direct current; and the current, in the circuits with which these symbols are used, always flows in the same direction when the respective circuits are closed. The source of current supply for the line circuits is represented by a battery BT having a center tap connected to the common return line (see Fig. 1B). This battery has its positive and negative terminals designated by symbols (3+) and (B-), which are used to designate the connections of various circuits thereto throughout Figs. 1A and IE to simplify the circuits of the control ofiice. It will be noted that where a circuit is indicated as connected to terminals (13+) and (B) the current flow in such circuits may be reversed in accordance with the conditions to be met, as provided for by the system of the present invention.

The operations of this communication system are preferably performed by relays of the tractive armature type. Certain 'of these relays, such as the line relays L, are of the three-position polarized type, the movable armature being biased to assume an intermediate or neutral position when the relay winding is deenergized. When such polar relay is energized, the armature assumes one or the other of two opposite extreme positions in accordance with the direction of current fiow in its winding. The contacts for these relays have been shown conventionally, and for convenience it is assumed that the contact fingers assume right hand extreme positions by the application of positive current and assume left hand extreme positions by the application of negative current. Some of these relays are of the two position polar type, similar to the three-position polar type relay with the omission of the means biasing their contacts to intermediate deenergized positions. The contacts of these two-position polar type relays remain in the position to which they are last energized even after their windings are subsequently deenergized. The contact fingers for these two-position relays are similarly. shown in a conventional manner, and are assumed to ,be moved to right-hand extreme positions'by the application of positive current, and to left-hand extreme positions by the application of negative current.

All other relays are of the neutral type, shown conventionally, and are preferably of the type employed in telephone practice. Certain of these relays require two windings in accordance with their use in the circuits, and certainothers require slow releasing characteristics which are obtained in the usual manner by the use of short circuited windings associated therewith. All of these relays are constructed according to the usual engineeringpractice having suitable characteristics for their various uses as employed in the circuits according to the present invention, quick operation of all relays being desirable except in the case of those relays having slow acting characteristics as conventionally illustrated by heavy base lines on such relays.

The control ofiice equipment.--The equipment for the control oflice includes in general a suitable control machine provided with manually operable levers, a track diagram, indicating lamps,

and the like, so as to enable the operator by simple manipulation to control the signals, switches and the other trafiic controlling devices of the system at the various way stations, and also have before him information of the response of such trafiic controlling devices, and of the occupancy of various track sections, such as Will enable him to handle the traffic over the system to the best advantage.

No attempt has been made to illustratetheconstruction of the control machine or the arrangement of parts preferably employed; but the manually operable control levers, the track diagram, indicating lamps, various relays and electrical connections have been diagrammatically illustrated to explain the function and operation of such system constructed according to the present invention, regardless'of its particular application in practice.

In the control office (see Fig. 1A) two manually operable levers SGL and SML are respectively provided for operating the signals and the switch at the west-endof a passing siding represented in the control office by a miniature passing siding on a track diagram. The lever SGL is of the three-position type having contacts I0 and H which make contact with their respective fixed contacts when in one of three positions; while the lever SML is of the two-position type having a movable contact [2 which makes contact with its respective fixed contacts when in extreme positions only. These levers are representative of all the manually operable levers on the control machine employed for the control of various traffic controlling devices in the field, each such lever being provided with what is termed a momentary contact, in this case contacts l3 and M for levers SGL and SML respectively, for momentarily closing a circuit as these levers are moved from any one of their positions to another.

The miniature track diagram, corresponding to the actual track lay-out in the territory under the supervision of the operator, is preferably made a part of the control machine positioned adjacent to the control levers for each of the several field stations. As representative of such a track diagram, the passing siding s is intended to represent an actual passing siding S in the field, such as shown in Fig. 2 of the accompanying drawings, and is located over its associated control levers SGL and SML.

Directly above the west end of this miniature passing siding s is located an indicator lamp I,

which, when lighted, indicates the occupied con,-

dition of a detector track section at the corresponding end of the passing siding S in the field. This lamp is controlled by an indication storing relay IS. It is to be understood that various other indicator lamps, or other means, can easily be employed to indicate the position of the switches, the condition of the signals and other similar conditions, such means being controlled in a similar manner, as shown for the indicator lamp 1.

Associated with each station is a storing relay SR, which is controlled by the momentary contact on each of the control levers included for that station. In other Words, these storing. relays register the operation of a control lever of the corresponding way station and remain energized until the new control set up by such movement of the control lever has been transmitted. A

Each of the storing relays SR has a corresponding code determining or selecting relay CD. These code determining relays CD are energized by their respective storing relays SR. and are arranged in a bank having their circuits so interlocked with the storing relays SR. that only one code may be superimposed upon the message circuit during any particular cycle of operation of the system. The particular one of these code determining relays CD, which is superior to the others, when energized, conditions the system for operation to cause the transmission of a code call characteristic of its corresponding station, in a manner more fully explained hereinafter.

Associated with each of the way stations is a message channel stepping relay bank, two such banks being shown in Fig. 1A for the respective way stations shown in Figs. 2 and 3. Y

The control office equipment includes a code channel stepping relay bank having associated therewith a group of code responsive relays. When the system is set into operation the relays of the code channel stepping relay bank operate sequentially closing code channels for the respective code responsive relays, which respond to the code being received or being sent in a manner to transfer the stepping operation from the code channel stepping relay bank at the end of the last code step to the particular message channel stepping relay bank corresponding to the code call characteristic received by the code responsive relays. The relays of the selected message channel stepping relay bank then sequentially step through to the last message channel step at which tim the system returns to its normal at rest condition, if there are no more new controls to be transmitted or new indications to be received.

Thus, the control machine in t e control office for each fie1d station includes two levers SGL, SML, a portion of track diagram with its indicating lamps, a storing relay SR, a code determining relay CD, a plurality of indication storing relays IS, and a message channel stepping relay bank.

The stepping relay banks count off the steps during each operating cycle of the system, relays preferably being employed for this purpose, but any other step-by-step mechanism could be used. In the arrangement shown providing for three station selecting or code steps (capable of selecting eight stations) and four control and indication steps, there are five stepping relays in the code channel stepping relay bank, namely, relays 1, 2, 3, 5, and a last code step relay LC; and there are five stepping relays in each of the message channel stepping relay banks, namely, relays 5, 6, 1, 8, and a last message channel stepping relay LM (for way station No. 1). It should be understood that this is only one arrangement and that the number of steps would be determined in accordance with the number of stations in use and the number of control and indication steps required for the various individual way stations.

The group of code responsive relays includes relays a, b and c, which are energized or left deenergized by their respective code channels. These code channels are set up by the code channel stepping relay bank.

The control ofiice equipment also includes suitable means for applying impulses of positive and negative polarity alternately, at time spaced intervals, to the stepping circuit. While a motor driven commutator or equivalent means might be employed, two impulsing relays IR and IE are used, each of these relays having slow acting characteristics in accordance with the time period desired to be marked off.

The control office equipment further includes a line relay L a slow acting relay SL, a cyc e controlling relay CC, a starting relay S, a local starting relay LS, a field starting relay FS, an a field control relay fc.

The relays of the control oifice are interconnected by various controlling circuits, buses, jumpers, and the like which will be discussed more in detail during the description of the operation of the system.

Field station equipment-With reference to Fig. 2 of the accompanying drawings, the signals l--I A and 22A with the track switch TS at the west end of a passing siding S are shown as merely illustrative or representative of the trafilc controlling devices which may be controlled and from which indications may be received as one field station.

The switch points TS are operated by a suitable switch machine SM, such for example as disclosed in the patent to W. K. Howe, No. 1,- 466,903 dated September 4, 1923, which is supplied with operating current from a local battery and which is preferably equipped with a dual control selector permitting hand operation of the switch points as disclosed in the patent to W. K. Howe, Patent No. 1,852,573, datedApril 5, 1932. The operation of this switchmachine SM is controlled by a function control relay SMR of the two position polar type, the energization of this relay being under the control of the operator through the agency of the communication system of the present invention. The operation of the switch machine SM is also governed by suitable approach and release locking means (not shown) such as disclosed for example in the application of W. W. Wenholz et al., Ser. No. 409,- 103, filed November 22, 1929, so that irrespective of the operation of the switch machine function control relay SMR the switch points TS may not be improperly operated.

Train movements over the switch TS are governed by the signals I--|A and 2--2A which are controlled by the condition of the associated track circuits, the position of the switch points, and in accordance with the position of the function relays DR and SGR, which are under the control of the operator for respectively determining in what direction traffic shall be established and whether or not the signals shall indicate clear for that direction. The circuits for controlling these signals in accordance with track conditions and the position of the switch points are not shown, but may be of the type shown and described for example in the application of S. N. Wight, Ser. No. 120,423, filed July 3, 1926.

A detector track section TK is associated with the track switch TS and is provided with the usual track battery [5 and track relay T to indicate the condition of occupancy of this track section.

According to the present invention, the communication system equipment for each field station includes the same arrangement of relays and the same circuits connecting the relays except in the case of certain jumpers or connections which may be rearranged or set to fit the particular code call characteristic of the station at which the equipment is located. These relays included within the communication part of the system of the present invention, are preferably housed in a portable cabinet or the like, so that they may be quickly detached in case of trouble to allow a new station unit to replace the old one.

The similarity between the various way station equipments is illustrated by the fact that the same reference characters have been applied to both Figs. 2 and 3 with similar parts having distinctive exponents, the only difference between these stations being the positions of certain jumpers which feature will be more specifically described hereinafter.

The field station equipment includes a line relay L; a slow acting relay SL; a change relay CH; a field control relay FC; a. code channel stepping relay bank having relays l, 2, 3, 4, and a last code step relay LC; a message channel stepping relay bank having relays 5, 6, 1 and 8; a group of code responsive relays including relays A, B, C, and a code responsive control relay CR. It is to be understood that the number of stepping relays is merely illustrative and will vary according to practice in accordance with the number of stations and the number of indications and controls desired to be transmitted.

The change relay CH is provided to be energized momentarily each time the detector track relay T drops or picks up; but it should be understood that the change relay may depend upon several way stations.

a change in position or condition of the signals,

track switch, or other track circuits in a similar manner so that various other indications, when provided, may be transmitted to the control offioe.

The field control relay F is energized when a particular field station initiates the system into operation. This field control relay has two functions, the first of which is to condition that stationin a manner so'that it may dictate the impulses placed upon the code or station selecting steps of the operating cycle to accomplish its own selection and its registration in the control ofilce; and second, to open the message line to subsequent way stations preventing interference from any other station which may be similarly conditioned at that time and endeavoring to send in indications.

With this explanation of the equipment and general organization of the system, it is believed zofithat the nature, the various characteristic features and functions of the system will be best understood by further description being given from the standpoint of operation.

Operation of the system ;;can arise in practice.

- The system is normally at rest with the step ping circuit, including the stepping line and the common'return line, deenergized, and with the message line having energy applied to it at the control office although no circuit is completed at this time.

During the time that the system is at rest or in a period of blank, it may be initiated into operation from the control office or any one of the When thus initiated. into operation, the system operates through a predetermined number of steps comprisingan operating cycle, after which the system returns to its normal or at rest condition'in readiness for the next initiation.

The means for impulsing the'stepping circuit is located in the control ofiice, so that the system may be initiated at the control oflice directly by starting this impulsing means; but when. the I system is initiated from a way station, the message line, which is normally'op'en-ended, is con-- nected by the change relay to the common return line at the particular station having new indications to transmit, which causes current to flow in a message circuit so as to initiate the im- '75? such initiation conditions that station in such pulsing means.

Each operating cycle includes the selection of a particular Way station; the transmission of controls for that station as set up by the corresponding control levers in the control omce; and the transmission of indications for that station as set up by the position of the traffic controlling devices located at that station.

If the system is initiated from the control office, every station is subsequently conditioned to receivecode call impulses, and the particular station having a code call corresponding to the impulses which are transmitted from the control oifice is then selected so that the controls and indications associated with that station may also a manner that subsequent thereto a combination of impulses corresponding to the code call of that stationis transmitted by that station, thereby selecting that station and registering it in the control oiilce, so that the'controls and indications associated with that station may also be transmitted. This functioning of the system is conveniently termed in-coming station selection.

Thus, each cycle of operation may be said to include five parts, namely, initiation into operation, conditioning for out-going or in-coming station selection, station selection by the transmission of code impulses, transmission of control impulses, and the transmission of indication impulses.

The transmission of control and indication impulses occurs during each operating cycle. If the system is initiated from the control oflice, the control impulses included in the resulting cycle of operation are new controls, while the in dication impulses included within that cycle are repeated as formerly transmitted; but if the sys-' tem is initiated from a way station, the indication impulses included in the resulting cycle of operation are new indications, while the control impulses included within that cycle are repeated as formerly transmitted. This repetition of controls and indications serves to check each way station. each time it is selected.

Thus, the description of the operation of the system of the present invention conveniently divides itself into two sections, namely, a description of the transmission'of new controls or outgoing station selection, and a description of the transmission of new indications or in-coming station selection. Following the description of these two functions of the system, their interrelation and co-action will be explained.

. Outgoing station selecti0n.With the system at rest or in theperiod of blank, the operator may accomplish the control of any traffic con-' trolling device over which he has supervision, by moving the corresponding control lever to a suitable controlling position. This operation of a control lever from a former position to a new position is registered or stored by a storing relay SR which in turn energizes a code determining relay CD, a local starting relay LS, a starting relay S and a cycle controlling relay CC. The system then operates through a cycle, due to a predetermined number of impulses placed upon the stepping circuit.

This energization of the storing relay SR corresponding to the way station with which the control lever is associated, and the energization of the corresponding code determining relay CD, determines that the resulting cycle of operation shall be one for out-going station selection, which may be best explained by considering the detail operations involved.

For convenience let us assume that the operator desires to operate the track switch TS at the first way station (see Fig. 2) from a normal extreme position to a reverse extreme position so that traffic mat be routed from the main track onto the passing siding S, or vice versa, in accordance with subsequent control of the governing signals.

Manual starting.To operate the track switch TS, the operator moves the contacts of the control lever SML to their extreme upper positions, and in so doing momentarily closes the contact l4 thereby energizing the storing relay SR through a circuit from through momentary contact l4, wires 11, I 8 and I9, winding of relay SR to Immediately, when the contacts of the relay sR 'assume" energized positions, a'

stick circuit for this relay is completed from through back contact 20 of relay CD wire 2|, front contact 22 of relay SR wires 23'and I9, windingof relay SR to The energization of the relay SR closes an energizing circuit for the code determining relay CD from back contact 39 of relay SL, wire 3!, front'contact 32 of relay SR wires 33 and 34, winding of relay CD wire 35, back contact 36 of relay LM, to

When the contacts of the code determining relay CD assume energized positions, this relay completes its own stick circuit from through back contact 37' of relay LM, wires '33 and 39, front contact 46 of relay CD wires 4! and 34,

Winding" of relay CD wire 35, back contact 36 of relay LM, to Also, at this time, the stick circuit of the relay SR v is transferred from back contact 20 of relay CD through'front contact 29 of relay CD to the control'of back contact 3? of relay LM, which circuit is now traced from through back contact 31 of relay LM, wires 38'and 42, front contact 29 of relay CD wire 2|, front contact 22 of relay SR wires 23 and I9, winding of relay SR to In this connection it is noted, that the contact 29 -of relay CD is preferably of the make-be'fore-break type, that is, a circuit from the heel of this contact through its back point is not opened until a circuit from the heel of this contact through its front point is completed, and vice versa, thus maintaining the stick circuit of the relay SR closed during the actuation of'the relay CD At the same time that the code determining relay CD is energized, the local starting relay LS is energized through a circuitfrom through front contact 45 of relay SR wires 45 and 41, upper winding of relay LS, to Immediately upon the energizationpof the relay LS its stick circuit is" closed from through back contact 59 of relay LM wire 5|, back contact 52 of relay LM, wires' 53*"and 54,- front" contact 55 of relay LS, lower winding of relay LS, to The energization of the local starting relay LS closes the energizing circuit'for the starting relay S from through back contact 58 of relay SL, wire 59, front contact 69 ofrelay LS, wire BI,

\ winding of relay S, to'

The energization of the starting relay S closes the pick-up circuit for the cycle controlling relay CC from frontcontact 62 ofrelay S, wires 63 and 64, winding of relay CC, to cycle controlling relay CC is then stuck up through a stick circuit from through back contact 59 of relay LM wire 5|, back contact 52 of relay LM, Wires 53 and 65,1front contact 55 of relay CC, wires 61 and B4, winding of relay CC, to

Energization of the cycle controlling relay CC closes its front contact Ill, thereby conditioning the stepping line circuit in readiness for receiving impulses of alternate polarity to operate the step-by-step means located at the control oifice and at each of the way stations. 7

The relay CC also closes an energizing circuit for the relay 1R from through front c0ntact II of relay CC, wire I2, back contacts I3, 14, I5 and 16 of relays"l, 2, 3, 4 respectively, wire ll, back contacts 18, I9, 89, 8| and 82 of relays 5, 6, "I, 8 and LMrespectively, wire 83, back contacts 84, 85, 86, 8'! and 88 of relay 5 6 1 8 and LM respectively, through similar contacts of the message channel stepping relay This banks corresponding to the other stationstof the system, through the: bus: wire 90, back contact 95' of relay 1R winding of relay R to The energization of the relay 13 causes positive potential to be applied to the stepping line circuitfronr the positive terminal of the battery BT indicated as (B+) through back contact 96 of relay 1R frontco-ntact 91 of relay IRA, wires 98 and 99, front contact IQ of relay CC, Wire I99, winding of'relay L, through the stepping line toithe several stations including therein the line relays L at each of those stations, to the common return line at the last station, thence to the mid-point of battery BT (see Fig. 4).

The energization of the stepping circuit causes the step by step'means (shown as relays) at the control office and at each of the way stations to take one step, as hereinafter pointed out. This energiz'ation' of the first stepping relay at the control office and at each way station occurs during the interval of time existing between the actuation of the polar contact of the line relay L" to its right-hand. energized position and the response of the contacts of the slow acting relay SL thereto.

In the control office, the energization of the first stepping relay opens the formerly traced energizing circuit of relay 1R at back contact 13 of relay I, which Would then cause the relay IE to be deenergized and as soon as the contacts of this first stepping relay assumed energized positions, thus causing the first positive impulse on the stepping circuit to be of insufficient duration to energize the relays SL.

But, the relay 1133' is maintained energized until the relay SL has assumed an energized position, due to a holding circuit including a front contact of relay I and a front contact of the starting relay S. This circuit may be traced from through a front contact II of relay CC, wire I2, front contact 13 of relay I, wire IIlI, front-contact I02 of relay S, wire I03 to bus 90, back contact 95 of relay IR winding of relay 1R to When the'relay SL is: energized, the relay S is deenergized at back contact 58, thereby breaking the holding circuit of the relay 1R at front contact I82 of relay S and completing the energizing circuit for the relay IR? from front contact?! of relay CC, wire 12, front contact I3of relay I, wire IOI, back contact I02 of relay S, wire I04 to bus 9|, back contact I05 of relay IE winding of relay 1R to The energization of the relay 1R causes negative potential to be applied to the stepping circuit from the negative terminal of the battery BT indicated as (B-) through front contact I U! of relay 1R back contact I98 of relay IR wires I99 and 99, front contact III of relay CC, wire I95, winding of line relay L, through the stepping circuit'as heretofore traced to the mid-point of battery ET.

The energization-of the stepping circuit with negative potential causes the polar contacts of the line relays L to'be operated to left hand positions, causing the step-by-step means at the control office and at each of the Way stations to take the second step.

' The en-ergization of the second stepping relay 2 in the control o-iiice deenergizes the stepping relay I thereby opening the energizing circuit of the relay "1R at front contact I3 of relay I". As soon as the relay IE is deenergized, which is an appreciable length of time after the deanergization of the relay I, the bus 99 is energized through front contact M of relay 2 thereby energizing the relay 1R tive potential upon the stepping circuit causing the step-by-step means at the control oflice and at each of the way stations to take the third step. In a similar manner as the relays I" and 2 have alternately energized the buses 90 and 9 I, likewise the subsequent stepping relays, such as relays 3, 4, 5, 6, 1, 8 and LM cause these buses 90 and 9| to be alternately energized, resulting in the alternate energization of the relays IR and IE respectively, to place impulses of alternate polarities upon the stepping circuit. When the last message channel stepping relay LM, such for example as LM is energized, the stick circuit for the relay CC is opened at the respective back contact (in this case back contact 52) thereby deenergizing it, which in turn removes the current supply for the impulsing relays IR at front contact 'II of relay CC, causing the impulsing of the stepping-circuit to cease. v

As We have now considered the manner in which the step-ping circuit may receive impulses of alternate polarity, we shall now consider the manner in which the application of these imipulses to the stepping circuit causes the stepby-step means at the control ofiice and at each way station to sequentially and synchronously operate.

Step-by-step operation-From. the above description, it can be seen that the manual starting of the system causes the application of the first impulse to the stepping circuit, while the response of the step-by-step means in the control office causes the application of the second impulse. Hence, the impulsing of the stepping circuit and the operation of the step-by-step means are interdependent.

However, for convenience let us consider that the manual starting causes the first impulse to which the step-by-step means responds, thus causing the second impulse, and so on as above explained, in order to observe how the step-bystep means at the central office and at each way station responds to such impulses.

For convenience, the code channel stepping relay bank at the first way station (see Fig. 2) will be more specifically considered in pointing out the operation of the stepping relay banks, although it is to be understood that the operation of every stepping relay bank is identical and may be readily understood by analogy.

With the first impulse of positive polarity placed upon the stepping circuit, the contacts of the line relay L are energized to right-hand extreme positions energizing the relay SL from through contact H0 of relay L in a righthand position, wire III, winding of relay SL, to As this first impulse is of relatively long duration in respect to the following impulses the slow acting relay SL receives current for a sufficient period of time to actuate its contacts to energized positions.

During the time that the line relay L is energized and the contacts of the relay SL have: not yet responded, a pick-up circuit for the relay I is closed from through contact II5 of relay L in a right-hand position, wire H6, back contact N1 of relay SL, lower winding of step-- ping relay I, wires H8 and H9, back contact I20 of stepping relay 2, to This pick-up circuit for the relay I is. closed until the contacts of the relay SL assume energized positions at which time its stick circuit is closed from front contact I2I of the relay SL, wires I22 and I I23, front contact I24 of stepping relay I, upper This again places posiwinding of stepping relay I, wires I25 and H9, back contact I20 of stepping relay 2, .to It is noted in this connection, that the front contact I2I is to be preferably closed before the back contact In is opened.

When the relay SL becomes energized with the stepping relay I energized, a circuit is completed from (-1-), through contact II5 of relay L in a right-hand position, wire H6, front contact II! of relay SL, wire I26, front contact I2'I of relay I, lower winding of relay 2, wires I28 and I29, back contact I30 of relay 3, wires I3I, I32 and I22, front contact I2I of relay SL, to It is obvious that both ends of this circuit are connected to the same terminal of the source thereby leaving the stepping relay 2 unaffected.

However, upon the energization of the line relay L with the opposite polarity in response to the next impulse on the step-ping circuit following an intervening period of deenergization, negative potential is connected to this circuit through contact II5 of relay L in a left-hand position. This effectively energizes the stepping relay 2, opening the stick circuit for the stepping relay I at back contact I20 and closing its own stick circuit through front contact I20. This stick circuit for the relay 2 is traced from through front contact I2I of relay SL, wires I22, I32 and I3I, back contact I30 of relay 3, wires I29 and I33, upper winding of stepping relay 2, front contact I20 of stepping relay 2, to

In a similar manner, the energization of the line relay L with alternate polarities causes the remaining stepping relays 3, 4 and so on to be sequentially energized each closing the pick-up circuit of the succeeding relay and opening the stick circuit of the preceding relay. The point to be noted is, that the closure of a pick-up circuit by a preceding stepping relay is not efiective until the proper polarity is applied thereto by the line relay upon the next energization of the stepping circuit.

Execution period-This sequential and simultaneous operation of the stepping relay banks at the control office and at each of the way stations is employed to close channel circuits over the message and common return lines between the control ofiice and each of the way stations. These channel circuits may then be employed for the transmission of various conditioning impulses, code call impulses, control impulses and indication impulses in a manner to be hereinafter explained.

These channel circuits are completed during the time that the stepping line is deenergized, which condition is employed to mark off what is conveniently termed as the message or execution period of each step. In other words, the energization of the stepping circuit accomplishes the energization of a stepping relay at the control office and at each of the way stations, but the preceding stepping relay must thereafter be dropped out thus causing an overlapping of the steps. However, if the channel circuits are completed only when the stepping circuit is deenergized, the stepping relays at the control office and at each of the way stations are in what may be termed a static condition so that any circuit completed at that time can not possibly overlap with any other circuit which may be completed on the next step during a similar time period.

Eacfi impulse placed upon the stepping'circuit, except the first as heretofore explained, is of a durationincluding the energizing time of the line relay L, the energizing time of a corresponding stepping relay, and the deenergizing time of the corresponding impulsing relay IR, While the time interval between successive impulses includes the pick-up time of the corresponding relay IR. During the energization of the line relays L, the proper stepping relay for that impulse is energized and remains energized until the next step is taken so that during the time of deenergization of the line relays marking off the execution period, sufficient time may be allowed by the pick-up time of each one of the impulsing relays IR to insure the operation of the relays controlled over the channel circuits.

Conditioning of field stations for the reception of code cclls.-The control oflice and each Way station is provided with a group of code responsive relays which are controlled through their respective channel circuits. In order that the proper stat-ion may be selected or chosen from among'all of the stations, the corresponding code responsive relays at the control office and at each station must be connected in multiple between the message line and the common return line on corresponding steps, but as such a multiple connection of the code responsive relays is undesirable at the way stations during an in-coming station selecting cycle of operation, each Way station must be conditioned at the beginning of an out-going station selecting cycle in order that its code responsive relays will be eifectively governed by the code impulses placed upon their respective channel circuits.

This conditioning of each station for the reception of code impulses or code calls at the beginning of an out-going station selecting cycle, is accomplished on the first channel circuit completed when the first stepping relay at the con trol ofiice and at each of the Way stations is energized. If this channel circuit is energized then every station is conditioned for the reception of code calls; While, if this first channel circuit is not energized, no station is conditioned for the reception of code calls.

As the system for this operating cycle under consideration has been initiated from the control oifice, the field control relay is at the control oifice is deenergized, this deenergization causes this first conditioning channel circuit to be energized.

In other words, the system has been manually started or initiated into operation from the control office resulting in the energization of the first stepping relay at the control office and at each of the way stations, upon which step a channel circuit is completed during the execution period of the step, that is, with relays IR and IR. deenergized, from the positive terminal of the battery BT indicated as (13+), through back contact Md of relay fc, wire MI, front contact I42 of relay I, wire hi3, back contact I44 of relay 1R wire I45, back contact I46 of relay IR wire I41, front contact I48 of relay SL through the message line to every way station (at the first way station for example), through wire I50, front contact I5I of relay SL, wire I52, front contact I53 of stepping relay I, wire I 56, lower Winding of relay CR, wires I55, I56, I51 and I58, to the common return line, and thence to the mid tap of the battery ET. A similar circuit at each way station from themessage line through its corresponding code response con.- trolling relay CR is completed to the common return line. Thus, the energization of this channel circuit accomplishes the energization of the relays OR at each of the way stations in multiple,

thereby conditioning every station for the reception of code calls as determined in the control ofiice.

The code response controlling relay CR is maintained energized throughout the cycle of'operation by a stick circuit completed from through front contact IZI of relay SL, Wires I22, I32, I34, I35, I36, I37, I38 and I39, upper winding of relay CR, front contact I49 of relay CR, to A similar circuit is completed for the respective code response controlling relay CR at each of the other stations.

Transmission and reception of code calls.As the relay CR "at each of the way stations is energized, the code responsive relays at the way stations are connected in multiple across the message line and the common return line through their respective channel circuits. Although any number of stepping relays could be employed having a corresponding number of code responsive relays, only the stepping relays 2, 3 and 4 have been shown as having code responsive relays A, B and C respectively. It is evident that each of these code responsive relays A, B and C,

may be energized or left deenergized on its respective step, thus providing eight combinations which maybe assumed by the contacts of these relays by suitably arranging their energizing impulses. These eight combinations have been represented by symbols in a Typical table of codes (see Fig. 5), a symbol representing the energized condition of the corresponding relay or a symbol representing the deenergized condition of that relay.

With reference to the Typical table of codes (see Fig. 5), a code call requiring the three code responsive relays A, B and C to be energized is represented by code call No. 1 and further denotes that the channel circuits for these three code responsive relays should each be energized in order to select the station having that code call assigned to it. Similarly, the code call No. 7, for example, indicates that the respective channel circuits for the code responsive relays A, B and 0 should be deenergized, deenergized and energized in. order to select the station having that code call characteristic.

For this particular cycle of operation under consideration, the control lever SML in the control ofiice has been operated resulting in the energization of the code determining relay CD which must provide energization of proper code channel circuits to select the first way station (see Fig. 2). This first way station has been assigned arbitrarily the code combination or code call symbolically represented in the Typical table of codes (see Fig. 5) by code call No. 3, which requires that the first and third code channel circuits shall be energized to energize relays A and C. In accordance with this, code jumpers I60 and I62 have been provided so that when the code determining relay CD is energized, the first and third code channels (closed when stepping relays 2 and 4 are energized and the stepping line is deenergized) may be energized.

Considering that the stepping relay 2" in the control ofiice and the stepping relay 2 at each of the way stations are energized, then during the execution period of that step, a code channel is completed for energizing the code responsive relay a in the control office and the corresponding code responsive relay A at each of the way stations from the positive terminal of the battery BT indicaed as (3+), through code jumper I60, front contact I63 of relay CD Wire I64, back contact I65 of relay fc, wire I66, lower winding of relay a, wire I61, front contact I68 of stepping relay 2, back contact I42 of stepping relay I", wire I43, back contact I44 of relay 1R wire I45, back contact I46 of relay 1R wire I41, front contact I48 of relay SL, through the message line to each of the way stations, (at the first way station for example) through wire I50, front contact I5I of relay SL, wire I52, back contact I53 of stepping relay I, front contact I69 of stepping relay 2, wire I10, lower winding of relay A, code jumper I80, to the code bus 260, back contact I1I of relay FC, 'code bus 20I, front contact I12 of code response controlling relay CR,

Wires I13, I56, I51 and I58, to the common return line, and thence to the mid point of the battery BT. Similarly, the relays A A etc., at the second, third and remaining way stations respectively are energized during this closure of the first code channel circuit, it being understood of course that these relays A at each station are in multiple across the message line and the common return line.

The code responsive relay A is maintained energized throughout that cycle of operation by a stick circuit closed from through f'ront contact I2I of relay SL, wires I22, I32, I34, I35, I36, I31, I38 and 2I2, upper winding of relay A, front contact 2I3 of relay A, to This stick circuit is representative of the stick circuit completed by each of the code responsive relays when energized, the respective stick circuits being completed by the corresponding SL relay energized until the end of the particular cycle of operation.

During the execution period of the next step (third), the code channel circuit for that step is not energized due to the omission of a suitable code jumper in the control office (see Fig. 1A), similar to code jumper I60 provided in the case of the first code channel circuit. Thus, the code responsive relay b in the control oilice and the code responsive relays B at each of the way stations, remain deenergized.

During the execution. period of the next step (fourth), the code channel circuit for that step is energized from the positive terminal of the battery BT indicated as (3+), through jumper I62, front contact I14 of relay CD wire I15, back contact I16 of relay f0, wire I11, lower winding of code responsiverelay 0, wire I18, front contact I19 of stepping relay 4, back contacts I85, I68 and I42 of relays 3, 2 and I respectively wire I43, back contact I44 of relay 1R wire I45, back contact I46 of relay 1R wire I41, front contact I48 of relay SL through the message line to each of the way stations (at the first way station), for example, through wire I50, front contact H of relay SL, wire I52, back contacts I53, I69 and I86 of relays I, 2 and 3 respectively, front contact I81 of stepping relay 4, wire I88, lower winding of code responsive relay C, code jumper I82, code bus 200, back contact H! of relay FC, code bus 26!, front contact I12 of code response controlling relay CR, wires I13, I56, I51 and I58, to the common return line, and thence to the mid-point of the battery BT. Similarly, the code responsive relays C at each of the way stations are energized as they are connected in multiple across the message and common return. lines.

In a similar manner a larger number of code responsive relays could be employed but for the purpose of a disclosure of the present invention only three such relays have been shown.

, At the first Way station (see Fig. 2 a circuit is completed through contacts on the respective relays A, B and C and a chain of connecting code bank to the message channel stepping relay bank at that station. At the second way station and at all other way stations, the contacts on the relays A, B and C and the chain of connecting code jumpers at those stations do not complete a circiut for transferring the stepping operation to the message channel stepping relay banks: at those stations.

On the fifth impulse of the stepping circuit, the last code channel stepping relay LC at every station is energized and locks up the stepping operation at all of the stations except the first (see Fig. 2), where the stepping relay is energized in multiple with the last code channel stepping relay LC at that station.

This pick-up circuit for the stepping relay 5 is closed from (-1-), through polar contact H5 of line relay L in its right hand position, wire I I6, front contact I I1 of relay SL, wire I26, back contacts l21, I96 and It of relays I, 2 and 3 respectively, front'contact I92 of stepping relay 4, wires I93 and I94, front contact I95 of code responsive relay A, code jumper 205, back contact I96 of code responsive relay B, code jumper 266, front contact 591 of code responsive relay C, code jumper 201, wire I98, lower winding of stepping relay 5, wires I99 and 2I0, back contact 2II of stepping relay 6, to These message channel stepping relays 5, 6, 1 and 8 are sequentially energized upon the application of the corresponding impulses upon the stepping circuit.

As the step-by-step operation. at a particular selected station must be transferred from the code channel step-ping relay bank to the message channel stepping relay bank, when the code responsive relays assume positions corresponding to the code call assigned to that station, then the chain circuit through the front or back contacts of the code responsive relays must be cornpleted when these relays assume the positions corresponding to the code call. Thus, it is obvious that the code jumpers 205, 266 and 281 at each station must be positioned to connect with the front or back contact of their respective code responsive relay in accordance with the code call of that station. For example, the jumper 205 should be connected to the front contact of the' certain code jumpers at each station.

As the code jumpers 295, 206 and 261 are arranged in accordance with the code combinations or code calls, and as a particular combination occurs but once, then it is obvious that with the code responsive relays assuming corresponding positions at all stations, the chain circuit for transferring the step-by-step operation from the code channel stepping relay bank to the message channel stepping relay bank will be completed at but one station.

Should a greater number of stations be employed with the system, a greater number of code responsive relays would be required, three such code responsive relays providing eight combinations, four relays sixteen combinations, five relays thirty-two combinations and so on in geometrical progression with the constant ratio of two.

With reference to the control oifice (see Figs. 1A and 1B), the code responsive relays a, b and c are in energized, deenergized and energized positions respectively, the relays a and having been energized through the same circuits as traced for relays A and C. These code responsive relays a, b and 0 each have stick circuits closed when they are energized until the end, of the operating cycle in which they are energized. For example, the stick circuit of the relay a is closed from through front contact 58 of relay SL, wires 2M, 2l5 and 2H5, upper winding of relay (1., front contact 211 of relay a, to

A chain circuit is completed by the code responsive relays for transferring the stepping operation from the code channel stepping relay bank to a message channel stepping relay bank corresponding to the station which is selected in response to the code call as registered upon these code responsive relays.

The eight combinations or eight chain circuit selections which may be made by the code responsive relays a, b and c are brought out to eight suitable terminals to which the pick-up or lower winding of the first stepping relay in the message channel stepping relay bank of the corresponding station may be connected. For example, the message channel stepping relay bank for station No. 1 must be connected to the particular one of the eight terminals that will have the chain circuit completed when the code call assigned to the first station has been transmitted or received. Thus, the lower winding of the stepping relay is connected to the third terminal by a jumper connection indicated by a do-ted line, thereby cornpleting a pick-up circuit for this relay upon the energization of the line relay L in response to the fifth impulse applied to the stepping circuit. This pick-up circuit for the stepping relay 5 is closed from through polar contact 226 of relay L in a right hand position, wire 22 l, front contact 222 of relay SL, wire 223, back contacts 22%, 225 and 226 of stepping relays l, 2 and 3 respectively, front contact 22'l of stepping relay 4, wires 228 and 229, front contact 239 of code responsive relay a, back contact 23l of code responsive relay in, front contact 232 of code responsive relay 0, through jumper 233, wire 234, lower winding of stepping relay 5, wires 235 and 236, back contact 237 of stepping relay 6, to Thus, stepping relay 5 is energized in multiple with the last code channel stepping relay LC and the relays 6, 5, 8 and LM sequentially step in response to the application of their respective impulses to the stepping circuit.

In a similar manner, if the code responsive relays a, b and 0 were energized or deenergized in any other code combination, the corresponding message channel stepping relay bank would thereby be selected, that is, the step-by-step operation would be transferred to that stepping relay bank.

In the control office, the last code channel stepping relay LC is energized simultaneously with the first stepping relay of the message channel stepping relay bank which has been selected for the particular cycle of operation. ihe energization of the stepping relay LC, opens the stick circuit of the stepping relay 4 at back contact 23%, thereby allowing the contacts of the relay 8 to assume deenergized positions completing the message line to the message channel stepping relay bank for the station selected (in this case the message channel stepping relay bank for sta tion No. 1). Similarly, at each of the way stations, the last code channel stepping relay LC is energized upon application of the fifth impulse to the stepping circuit, thereby opening the stick circuit of the stepping relay t at every station. This removes the code responsive relay C at the respective stations from their multiple connection to the message line and the common return line. These relays LC remain energized until the end of the operating cycle through a stick circuit including front contact 52! of relay SL thereby locking up the step-by-step operation of each of the stations except the particular station which J received its characteristic code call. At this sta tion the stepping relay 5 is energized in multiple with the relay LC at that station and the stepby-step operation is transferred to the message channel stepping relay bank of that station, as heretofore explained.

Transmission of new contr0ls.-After a station is selected in response to the transmission of its code call, the step-by-step operation in response to the impulses applied to the stepping circuit occurs in the message channel stepping relay bank at that station. and in the message channel relay bank in the control ofiice corresponding to that station. In this particular case, the message channel stepping relay bank at the first way station (see Figs. 2 and 1A) will have the respective relays 5, 6, l and 8 sequentially step in synchronism with the relays 5, 6, l and 8. The eighth step is followed by an extra step for purposes hereinafter pointed out.

Each message channel stepping relay bank in the control ofiice for the respective way station is capable of connecting upon the respective channel circuits certain contacts on the levers of the corresponding station to the message line, in a manner such that the function control relays at the way station will be operated through the respective channel circuits in accordance with the position of the corresponding levers of that station located in the control office.

In this case, the control levers SML and SGL, associated with the first way station, have contacts which control the energizati-on and the polarity thereof of the message channel circuits completed by the message channel stepping relay bank for this station. For example, upon the fifth step of this cycle of operation under consideration when the relays 5 and 5 are energized and the stepping circuit is deenergized to mark off the message or execution period for that particular step, a circuit is completed from the contact 22 of the lever SML through the switch machine function control relay SMR at the first way station applying the proper polarity in accordance with the position of the lever SML.

As the operator moved the lever SlVl'L to a reverse position to operate the track switch TS to a reverse position, negative potential is applied from the terminal of the battery B'I indicated as (B), through contact if in a dotted line position, wire 2%, front contact 24 of relay 5, wire 2 32, back contacts H9, 585, i623 and 442 of relays i, 3, 2 and 5 respectively, wire M3, back contact M l of relay 1R wire M5, back. contact MS of relay IE wire Ml, front contact I48 of relay SL, through the message line to the first way station, wire I50, front contact 55'. of relay SL, wire 32, back contacts 553, E69, E86 and E8! of relays l, 2, 3 and 4 respectively, wire 2%, front contact 264 of stepping relay 5, wire 245, Winding of relay SMR, wire 246, front contact 241 of Stepping relay 5, Wires 248 and I58, to the common return line and thence to the mid-point of the battery ET in the control ofiice.

This application of negative potential to the relay SMR, causes its polar contact to be actuated to a'left hand dotted line position which results in the operationof the switch machine and the controlling of the track switch TS to a reverse position, so that traflic may be routed onto or oif of the passing siding S in accordance with the clearing of the governing signals IA or 2A respectively.

With the lever SGL in a central position, the second message channel circuit is not energized during the message or execution period of the sixth step, thereby allowing the polar contact of the direction control function relay DR to remain in a position as formerly actuated.

However, the third message channel circuit is energized with negative potential with the lever SGL in a central position during the message or execution period of the seventh step thereby energizing the relay SGR through a circuit which may be traced by analogy to the circuit traced for the relay SMR. Thus, the polar contact of relay SGR is actuated to a left hand position, which determines that the signals I-IA and 22A shall display stop indications.

The manner in which these function controlling relays SMR, SGR and DR control their respective traffic controllingdevices is only indicated by dotted lines, it being understood that the control may be accomplished in any suitable manner, such for example as shown in the patent to S. N. Wight, Patent No. 1,889,457, dated November 29, 1932. It is also to be understood, that any number of function control relays may be employed for operating various other traffic controlling devices the same as, or different, than those illustrated, these relays being operated in accordance with control contacts in the control office over message channel circuits provided by extra stepping relays.

If some other station had been selected, such for example as the second way station shown in Fig. 3, a. message channel stepping relay bank corresponding to that station in the control office would be sequentially operated in synchronism with the message channel stepping relay bank at the second way station. The channel circuits set 'up thereby would be governed by similar control levers SML and SGL (not shown) associated with the second Way station. In other words, thegroup of levers corresponding to each station is associated with a corresponding group of message channel stepping relays being permanentlyconnected 'to the front contacts of the respective relays closing the proper channel circuits provided thereby. I

Transmission of old indications-As this cycle of operation was. initiated in response to the movement of a control lever in the control ofiice, it can be easily seen that one or more of the controls resulting therefrom will. be new controls, but in all probability the indications, transmitted during such a cycle of operation, will be old indications, that is, indications transmitted in accordance with the position of traffic controlling devices at that way station prior to the transmission of the controls, and as formerly transmitted.

Upon the seventh step, or more generally speaking, upon the step preceding each particular step assigned for the transmission of an indication impulse, a; resistance is included in the stick circuit of the corresponding stepping relay in the control office. A drop in potential occurs across this resistance during the execution period of that step which is employed to actuate the polar contact of an indication storing relay IS to a normal position. If on the next step, during the completion of its message channel circuit, the indication contact at the way station which governs this relay, is closed, then the polar contact of this indication storing relay will be actuated to an opposite or reverse position. This actuation will not be cancelled until the station is again selected, in order toinsure that the indication will be stored and be a true indication of the position of the governing indication contact at the way station. If the governing indication contactv is not closed, then this polar contact will remain in its normal position as: controlled by the potential drop across the resistance.

This has been more specifically pointed out for the indication storing relay IS which has a resistance R connected in series with the stick circuit of the stepping relay 1. When current flows through this stick circuit including the resistance R, a drop in potential is created across the resistance which causes current to flow from its left hand terminal through wire 25%, lower winding of relay IS, wire 25!, to the right hand terminal of this resistance. It is to be understood of course, that the source of supply furnishing current for the stick circuit, also furnishes this-current for the relay IS. This flow of current actuates the polar contact of relay IS to a left-hand position (as shown).

During the message or execution period of the eighth step, a channel circuit is closed or left open in accordance with the positon of the contacts of the trackrelay T. In this case, there is no train upon the detector track section 'IK, therefore the track relay T will be energized. Thus, this indication channel circuit will remain open allowing the polar contact 252 of relay IS to remain in its left hand position, as actuated by the drop in potential across the resistance R.

If this circuit had been closed due to the deenergization of the track relay T, this polar contact 252 of the relay IS would be operated to a right hand position and indicate the occupied condition of the detector track section TK by the energization of the indicator lamp I, through a circuit obvious from the drawings.

It is to beunderstood that a greater number of channel circuits can be employed to provide .a greater number of indication message channel circuits, so that indication of Various other con.- ditions such as indication of the position of signals, position of switches, and the like, may be provided for assisting the. operator in directing traffic over that part of the railroad under his supervision.

It is to be understood that indication storing relays similar to the relay IS are to be associated with each way station and are similarly controlled over channelcircuits provided by the message channel stepping relay bank corre sponding to the station with which they are associated. 7

End of Operating cycle-After the eighth stepping relay in the message channel stepping relay bank in the control oflice corresponding to the station selected and the corresponding message channel stepping relay bank at the selected station has been energized, another impulse is placed upon the stepping circuit to cause the last message channel stepping relay LM to be energized. This opens the stick circuit of the stepping relay 8. The relay LM closes its own stick circuit and remains energized until the re lay SL is deenergized, but it also opens the stick circuits of the relays SR CD LS and CC at the contacts 37, 36 and 52. The deenergiation of. the relay CC opens the stepping circuit at front contact 'l'll thereby causing the line relays L to remain deenergized. The starting relay S cannot be energized as long as the relay SL is energized; and; the stepping line cannot be energized until the relay CC is energized by the relay S. Hence, as the stepping line remains deenergized another cycle of operation cannot be initiated until the relay SL has been deenergized, which occurs a predetermined time period after the last energization of the line relay L This in.- sures that the relays SL at every station will be deenergized, at which time the system will be restored to a normal at rest condition, even if another cycle is to be initiated. However, if no control lever is moved or no new indication occurs at a way station, the system remains at rest.

Sequence of outgoing station selection-It will be evident that the code responsive relays at each of the stations are capable of assuming but one combination of energized and deenergized positions, which combination is assumed in accordance with the particular channel circuits which are energized during the station selecting part of the operating cycle. Should two or more code calls or combinations of impulses be applied to the message line during the station selection part of the operating cycle, then the code calls would be mutilated and cause the selection of some station unintentionally.

This mutilation of code calls may be best understood with reference being made to the Typical table of codes (see Fig. 5). If the code call No. 3, provided for the first way station, and the code call No. 6, provided for the second way station, are combined, it is obvious that the code call No. 6 is the one which is actually existent during the station selecting part of the operating cycle. Thus, the station having code call No. 6 assigned to it is unintentionally selected and erroneously controlled.

Of course the operator could be relied upon to actuate a lever for the selection of a particular station and then allow sufficient time for the controls to be transmitted in accordance therewith before operating another lever; but such a procedure would considerably handicap the operator in planning train movements and limit the extent of the territory which one operator could adequately supervise.

In accordance with the present invention, means is provided, whereby the control levers for the various stations may be moved simultaneously or in rapid succession, with said means automatically determining the sequence of the transmission of the proper code calls to prevent any mutilation thereof.

This means, which determines the sequence of out-going station selection by determining the code calls which are transmitted, includes a storing relay SR for each group of levers associated with a particular station, which storing relay is energized when any one of the levers of that particular group has been operated to a new position. Ihe energization of a storing relay SR, energizes its corresponding code determining relay CD when. the system is at rest, or in a period of. blank which occurs between two cycles of 0peration. Each of these code determining relays CD provides that the code call of its corresponding station is transmitted with the character of the code call determined by its associated code jumpers, such for example as the code jumpers I60 and l62 associated with the first way station. However, the circuits controlled by the code determining relays CD and associated code jumpers are so interlocked that the impulses of only one code call may be transmitted over the message line during the station selecting part of a particular operating cycle.

If more than one of the code determining relays CD is energized at a time, the code jumpers corresponding to the particular energized code determining relay CD which is farthest to the left, are caused to govern the energization of the code channel circuits; while the code jumpers of the other code determining relays (which are energized) to the right of the above mentioned code determining relay do not effect the code channel circuits. At the end of the operating cycle this particular code determining relay, which determined the code call for that cycle, is dropped out and the next code determining relay to the right of it which is energized determines the call for the succeeding cycle of operation.

This may be best understood by assuming that both the relays CD and CD are energized (see Fig. 1A). The code jumpers I69 and I82 are then conditioned to control the code channel circuits as heretofore pointed out. However, the code jumper 2Bl associated with the relay CD cannot effect the code channel circuit of. the third step, due to the opening of back contact I84 of relay CD nor can either of the two other code channel circuits be effected by the code determining relays and code jumpers to the right of the relay CD due to the open condition of back contacts I63 and H4.

It is obvious that when the relay CD is deenergized the wires I64, 255 and H5 will then be connected to wires 256, 251 and 258 permitting the next code determining relay to the right (which is energized) to then control the code channel circuits. In other words, the code channel circuits pass through chain circuits including contacts on the code determining relays CD, in a manner that when a particular relay is energized, it is effective to prevent the control of every code determining relay to the right of it.

These code determining relays CD may be picked up when the relay SL is deenergized as heretofore pointed out in connection with relay CD Thus, the particular code determining relay to the left, which is last energized during the time that the system is at rest or in a period of blank, is the one to transmit or determine the code call for the succeeding cycle of operation. The energization of the relay SL prevents the mutilation of a code call during transmission.

If the operator moves several levers while the system is in operation, the corresponding storing relays SR are energized, but the code determining relays CD corresponding to those storing relays are not energized until the end of that cycle of operation, at which time they are energized upon deenergization of the relay SL; but these code determining relays CD transmit the code calls in a sequence or order from left to right.

It is of course to be understood, that these relays SR do not have to be associated in an order in accordance with the geographic location of the stations, but each one of these storing relays may be associated with any way station desired. For convenience the storing relay SR has been associated with the group of levers for the first Way station, the storingrelay SR has been associated with the group-of levers for the second way station (not shown), and so on; but these storing relays SR SR could be associated with the other groups of control levers thereby changing the order of sequence in which the code calls of the respective stations are transmitted.

Incoming station selection.The selection of stations for the transmission of out-going controls, the transmission of these controls and the repetition of the indications associated therewith, is all accomplished, as above explained, over the message circuit. Also, the same message circuit is employed for the transmission or communication of impulses to accomplish station selection for incoming indications, the transmission of those indications and the repetition of the controls associated therewith.

This utilization of the message circuit to transmit impulses in either direction is made possible, due to the manner 11 which the system is. conditioned for either out-going station selection or incoming station selection.

As there are many trains passing over the system under the supervision of the operator, these trains may arrive at OS-ing points: simultaneously, thereby providing indications at several stations which are ready for transmission at the same time. Likewise, the operator may transmit controls to several stations, the resulting operations being completed at substantially the same time, thereby providing indications at the several stations to be transmitted to the control ofiice. However, as only one way station can be in communication with the control ofiice for incoming station selection during a particular cycle of operation, means is provided whereby the station having new indications to transmit which is nearest the control office is made superior to the others and locks them out, so to speak, during the initiation of the system from the field. In other words, the initiation from the field is employed as the conditioning period for determining which way station is superior and determining that the cycle of operation shall be for incoming station selection. ,Thus, the condiance with code call transmitted from the field.

For convenience, the selection of a single station and the transmission of its indications, controls and the like will be explained first, with the means of look-out for station superiority during incoming station selection pointed out at a later time.

Automatic starting.Whenever a change takes place in the occupancy of a detector track circuit, the position of a switch, signal or other trafiic controlling device which is required to provide an indication in the control ofiice, the system is automatically set into operation for the selection of the corresponding station. This change in conditions at a Way station is registered by the momentary closure of the pick-up circuit of the change relay CH at that station.

This momentary energization of the relay CH is sufiicient to actuate its contacts to energized positions, which completes a stick circuit for maintaining the change relay energized until the corresponding" station has been selected and the new indication transmitted.

-For convenience, let us refer to the first way station (see Fig. 2) and consider in detail the operation of the system when initiated from the field due to a change in detector track circuit occupancy, such an operation being considered as representative of all such operations which might occur due to a change in position of a signal, track switch or the like at this station or any other station.

The passage of a train onto or off the detector track section causes the contacts of relay T to assume deenergized or energized positions respectively, for reasons well understood. ,This movement of the contacts of the relay T causes the momentary or make-before-break contact of the relay to complete a circuit from through momentary contact 265 of relay T, wires 266 and 261, winding of relay CH, to This energizes the relay CH causing a stick circuit to be closed from through back contact 268 of stepping relay 5, wire 269, front contact 218 of relay CH, wires 21! and 261, winding of relay CH to With the system at rest, the energization of the relay CH shorts the message line to the common return line thereby completing a circuit from (B-|-), through back contact 212 of cycle controlling relay CC, Wire 213, Winding of field starting relay FS, wire 214, back contact 215 of relay SR wire 216, back contact 211 of relay SR wire 218, back contact I48 of relay SL' through the message line Wire to the first way station, wire I58, back contact I5| of relay SL, wire 219, front contact 280 of relay CH, wire 28I, upper winding of relay FC, Wires 282, 283, I51 and I58, to the common return Wire and thence to the midpoint of battery ET. The closure of this starting circuit energizes the field starting relay FS in the control ofiice and the field control relay FC at this way station. The field control relay FC is maintained energized, until that station has been selectively operated, by a stick circuit closed from through back contact 291 of relay 8, wire 298, front contact 299 of relay FC, lower winding of relay FC, to In a similar manner, the field starting relay F'Sand the relay FC at any other way station can be energized in series should the change relay at some other station become energized with the system at rest.

The energization of the field starting relay FS closes a pick-up circuit for the local starting relay LS from through front contact 284 of, relay FS, wires 285 and 41, upper winding of relay LS, to The relay LS becomes energized and closes its stick circuit, and also energizes the starting relay S, which in turn energizes the cycle controlling relay CC, all in a manner as heretofore pointed out for manual starting. Thus, the system is initiated into operation as the result of the change in the condition of occupancy of the detector track section TK at the first Way station. The energization of the change relay CH at that station for any other change in condition of traffic controlling devices, or the change relay at any other station, would result in a similar automatic initiation of the system.

Energization of the field starting relay FS also accomplishes the energization of a field control relay fc in the control office from front contact 286 of relay FS, wires 281 and 288, winding of relay fc, to This relay closes its stick circuit from through back contact 289 of relay LC, wire 290, front contact 298 of relay fc, wire 288, winding of relay jc, to The energization of the cycle controlling relay CC deenergizes the field starting relay FS at back contact 212, but this occurs subsequent to the energization of the relay fc as the energization of relays FS and S intervene between the energization of the relays FS and CC,

The energization of this field control relay ,fc determines that the conditioning channel circuit completed during the execution period of the first step shall be deenergized. In other words, the energization of the field starting relay FS determines that the cycle of operation is one for in-coming station selection which conditioning of the system is accomplished during the initiation thereof from the field.

Transmission and registration of code calls from a way station;Assuming the system to be automatically initiated into operation as above explained and impulses to be placed upon the stepping circuit causing the sequential and simultaneous operation of the step-by-step means at the control ofiice and at each way station, we will now consider the selection and registration of the first way station which is now ready to send in new indications.

During the execution period of the first step, the channel circuit for that step is deenergized. Thus, the relay CR at each of the way stations is left deenergized. This means that the code responsive relays at each of the way stations, except the way station where the relay FC is energized, are not connected to the message line and common return line on their respective channel circuits as explained for out-going station selection, as the front contact I12 of the relay CR is open.

However, the relay FC at the first way station, where the change has occurred resulting in the initiation of the system from the station, is energized. The energization of this field control relay FC closes its front contact I1I which connects those code responsive relays, which are necessarily energized for the selection of that station, through their respective channel circuits to the message line and the common return line. In the control ofiice the energization of the field control relay is causes positive potential to be applied to the message line from the battery ET on each of the code channel circuits. Thus, during the execution period of those steps where the channel circuits have the code responsive relays connected to the message line and the common return line, a circuit is completed which energizes the corresponding code responsive relays in the control ofiice and at the station which is transmitting the code call.

More specifically, during the execution period of the second step, a circuit is completed from the positive terminal of battery BT indicated as (B+), through front contact I65 of field control relay fc, wire I55, lower winding of code responsive relay a, wire I61, front contact I 68 of stepping relay 2, back contact M2 of stepping relay I, wire I43, back contact I44 of relay 1R wire Hi5, back contact I46 of relay 1R wire I41, front contact I48 of relay SL, through the message line to the first way station, wire I50, front contact i5I of relay SL, wire I52, back contact I53 of counting relay I, front contact I69 of stepping relay 2, wire I10, lower Winding of code responsive relay A, code jumper I80, through code bus 200, front contact I1I of relay FC, wires 283, I51 and I 58, to the common return line and thence to the mid-point of battery BT. Thus, the code responsive relays a and A, at the control office and at the first way station respectively, are energized and maintained energized through their stick circuits.

During the execution period of the third step, positive potential is applied to that channel circuit through front contact 292 of relay I0 and the code responsive relay b, but the code jumper I8I at the first station connects the code responsive relay B to the code bus 20I which inasmuch as front contact I12 of relay OR is open, this channel circuit is not completed during the execution period of this third step.

However, during the execution period of the fourth step, inasmuch as the code jumper I82- is connected to the code bus 200 at the first way station, the channel circuit for that step is completed to permit current to flow from the positive terminal of the battery BT indicated as (13+), through front'contact I16 of relay fc, wire E11, lower winding of code responsive relay 0, wire I18, front contact I19 of stepping relay 4, back contacts I85, I68 and I42 of stepping relays 3, 2 and I respectively, wire I 23, back contact I44 of relay 1R wire I05, back contact Hit of relay 1R wire I41, front contact I48 of relay SL, through the message line to the first way station, wire I50, front contact I5I of relay SL, wire I52, back contacts I53, I55 and I85 of stepping relays I, 2 and 3 respectively, front contact I81 of stepping relay 4, wire I88, lower winding'of code responsive relay 'C, code jumper 582, code bus 200, front contact I1I of relay FC, wires 283, I51 and I58, to the common return line and thence to the mid-point of battery BT.

Thus, the group of code responsive relays in the control oflice are energized and ole-energized in correspondence with the group of code responsive relays at the first way station, both groups assuming positions in accordance with the code call of the first way station. This correspondence causes the step-by-step operation at the control ofiice and at the first way station to be transferred from the respective code channel stepping relay banks to the message channel stepping relay banks corresponding to the first way station.

Fromfthe above description it can. be seen, that each, of the channel circuits, having code responsive relays connected therein, receive energy in the control ofiice due to the energization of the field control relay fc, while the actual completion of each channel circuit is dependent upon the position of the respective code jumper at the way station connecting that channel to either the code bus 200 or 20L If the code/jumper connects the channel circuit to the code bus 200, that channel circuit is closed and current flows therein to pick up the corresponding code responsive relays at the control ofiice and at the way station; while if the code jumper connects that channel circuit to the code bus 20L that channel circuit is not closed and current does not flow therein.

For example, the first way station has the code call No. 3 (see Fig. 5) assigned to it which requires the respective channel circuits of the code responsive relays A, B and C to be energized, deenergized and energized. In, accordance with this code call, the code jumpers lat and I82 are connected to the code bus 2530, thereby causing the respective channel circuits to be closed and energized upon their respective steps, while the connection of the code jumper I8I to the code bus 20I causes its respective channel circuit to be deenergized. In other words, the code jumpers I80, I8I and I82 at each station must be arranged in accordance with the code call of that station, each code jumper being connected to the code bus 2M3 if its channel circuit is to be energized as rep-resented by a symbol in the Typical Table of Codes, while if such channel circuit is to be deenergized as represented by a symbol then that code jumper is connected to the code bus 2M.

Transmission of old controls.Upo-n the application of the next impulse (fifth) to the stepping circuit for this cycle of operation, the last code channel stepping relay LC at the control office and at each of. the way stations is energized. At the control office the 'code responsive relays a, band 0 are assuming positions in. correspondence with the code call of the first Way station, hence upon the application of this fifth impulse, the stepping relay 5 will be energized in multiple with the relay LC.

At the first way station the code responsive relays A, B and C are assuming positions in correspondence with the code call of that station,

therefore upon the application of the fifth impulse the stepping relay 5 will be energized in multiple with the last code channel stepping relay LC, in a manner as heretofore pointed out. At all other way stations as the'code responsive relays at those stations are all deenergized the stepby-step operation will be discontinued with the energization of the relays LC at those stations.

Upon the energization of the relay LC in the control office, the field control relay fc is deenergized due to the opening of its stick circuit at back contact 285 of relay LC.

At the first way station the change relay CE is deenergized upon the energization of the stepping relay 5 due to the opening of back contact 258. As this stepping relay 5 is deenergized upon the next step, the change relay is then con.- ditioned for storing such other changes in position of traffic controlling devices at that station as may occur, subsequent to this fifth step.

The step-by-step operation of the system continues in a manner heretofore explained, closing the control channel circuits for the relays SMR, DR and SGR, causing them to be controlled in accordance with the positions of their corresponding levers in the control office. It is not considered necessary to describe and specifically point out the channel circuits for the function control relays SMR, DR and SGR, nor to assume certain positions for the control levers, as such operations have been previously explained.

However, it is to be noted in this connection, that in practice the lever SGL would bein such a position as to have previously caused the clearing of one of the signals I--IA and 2-2A in order for a train to pass onto the detector track section TK. However, it is to be assumed that such a condition or some other similar condition exists and that the controls in accordance therewith have been previously transmitted. Thus, the closure of the channel circuits for the control of the function control relays SMR, DR and SGR is a repetition and serves to check and maintain these function control relays in their previously operated positions.

Transmission of new indications;--Assuming the system. to operate up to the eighth step as previously explained, the indication storing relay IS is energized on the seventh step by the drop in potential across the resistance-R which-insures that the contact 252 is actuated to a left hand position.

If the track relay T is deenergized, the channel circuit closed during the execution period of the eighth step will be energized; but if the track relay is energized, that channel circuit will remain deenergized. If the channel circuit is energized, the polar contact 252 of the indication storing relay IS will be operated to a right hand position energizing the indicator lamp I in the control oflice, indicating the occupied condition of the detector track section TK in accordance with the shunted or deenergized condition of the track relay T. This energized condition of the indicator lamp I will exist, although the station is again selected causing the indication storing relay IS to be energized by the drop in potential across the resistance R, if the track relay is still deenergized, as the indication storing relay IS would again be energized through its respective channel circuit on the eighth step to again actuate the polar contact 252 to a right hand position.

For convenience assuming that the track relay is deenergize'd as heretofore pointed out to accomplish the energization of the relay CI-I, this indication channel circuit closed during the execution period of the eighth step from the positive terminal of the battery BT indicated as through upper winding of indication storing relay IS, wire 300, front contact 30I of stepping relay 8, back contacts 302, 353 and 24I of stepping relays 'I, 6, and 5 respectively, wire 242, back contacts I19, I85, I68 and I42 of stepping relays 4, 3, 2 and I respectively, wire I43, back contact I44 of relay 1R wire I45, back contact I46 of relay 1R wire I4'I, front contact I48 of relay SL, through the message line to the first way station, through wire I50, front contact I5I of relay SL, wire I52, back contacts I53, I69, I86 and IB'I of stepping relays I, 2, 3 and 4, wire 243, back contacts 244, 304 and 385 of stepping relays 5, 5 and I respectively, front contact 306 of stepping relay 8, wire 301, back contact 308 of track relay T, wire 305, front contact 31s of stepping relay 3, back contacts 3I I, 3I2 and 241 of stepping relays I, 6 and 5 respectively, wires 248 and I58 to the common return line, and thence to the mid-point of battery BT.

Also, upon the energization of the eighth stepping relay, the stick circuit for the field control relay PC at Lthe first way station is opened at back contact 2 91 of stepping relay 8.

End of operating cycZe.Upon the application of the next impulse (ninth) to the stepping cirwit, the last message channel stepping relay LM included in the message channel. stepping relay bank for station No. 1, is energized. The energization of this stepping relay causes the deenergizatio-n of the local starting relay LS and the cycle controlling relay CC, thus causing the sys tem to be returned to the at rest or period of blank condition in a similar manner, as explained for the end of an out-going station selection cycle of operation.

When the train passes off the track section TK, the change relay CI-I Will be again energized causing the system to operate through another cycle of out-going station selection. Such a cycle of operation will be similar to the one just explained with the exception that the indication channel circuit of the eighth step will not be' energized. This will leave the polar contact 252 of relay IS in a left hand position to which it is actuated on the preceding step (seventh). Other operations will be understood by analogy.

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