US2159922A - Centralized traffic controlling system for railroads - Google Patents

Description

2 Sheets-Sheet l I "I ml 6 R. F. WELLS Filed Sept. 22, 1932 May 23; 1939.

' 'CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS 8 I u T Y w k H la v a! 3 S.\ m

A E .58m wit R. F. WELLS I 2,159,922 CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAIL-ROADS Filed Sept. 22, 1932 2 Sheets-Sheet 2 May 23, 1939.

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Patented May 23, 1939 UNITED STATES PATENT oFFcs Robert F. Wells, Rochester, N. Y., assignor to General Railway Signal Company,

Rochester,

Application September 22, 1932, Serial No. 634,370

21 Claims.

This invention relates to centralized traffic controlling systems for governing traffic on railroads, and more particularly pertains tothe interrelation of the communication part of such a system with the trafiic controlling devices which are supervised thereby.

This invention is to be considered as an improvement over the prior application of Neil D. Preston, Ser. No. 573,079, filed November 5, 1931, and no claim is made herein to any subject matter disclosed in such prior application.

In a centralized trafiic controlling system of the type contemplated by this invention, communication is established between a central control office and. a large number of outlying field stations by means of a station selective coded type of communication system. In a communication system of this type, a plurality of series of impulses of different code combinations are transmitted over the line circuit connecting the control ofilce and the field stations, The first part of each different series of code combinations is employed for the selection of the station; while the later part of each different series of code combinations is employed to control the trafilc controlling devices at the selected station.

The present invention pertains more particularly to the manner in which the later part of each different series of code combinations is arranged in what is conveniently termed a composite route control code, and the manner in which such a route control code is employed to govern the traflic controlling devices at a station.

More specifically, a track switch and the signals for governing traflic thereover are governed in accordance with the conditions of control relays. The control relays for the track switch remain in the positions to which they were last actuated. Similarly, the signals are governed by signal control relays which establish the direction, but the particular route over the track switch for such direction is dependent upon a selection which requires that the switch control relays are in correspondence with the tralck switch.

These switch and signal control relays receive their selective energizations in accordance with the positions of their respective code receiving relays which are positioned by the route con- 0 trol codes comprising the latter part of each different series of code combinations. The code receiving relays are neutral relays, one neutral relay for each distinctive character of the impulse on each step, and these relays are all restored to 55 normal deenergized positions between the (iiiferent series of impulses for their station, thus giving what may be conveniently termed a clean slate.

Then upon reception of the new control code impulses, one code receiving relay or the other for each step is selected in accordance with the character of the impulse for that step. Upon the last step of a cycle of operation, the last impulse is effective to transfer or execute the positions of the code receiving relays to the switch and signal control relays, but the positions of the code receiving relays corresponding to the signal control part of the code, are not executed unless the switch control relays are in correspondence with the switch code receiving relays.

In other words, the complete number of steps must be taken for each series of impulses received by a station, and each impulse of such series must have positioned its corresponding code receiving relay, and the positions of the code receiving relays for the switches and the positions of the control relays for the switches must correspond in order for any route to be cleared. In this way, the integrity of the code reception is completely checked and the failure of a contact, as for example in the executing circuits, results in the failure of the setting up of a route, rather than the setting up of an undesirable or erroneous route.

Other features of the present invention reside in the various circuit arrangements particularly adaptable for systems of this type.

These characteristic features of the invention, thus briefly stated, will be explained more: in detail in the following description of one embodiment of the invention; and various other characteristic features, functions and advantages of a system embodying the invention will be in part pointed out and in part apparent as the description progresses.

In describing the invention in detail, reference will be made to the accompanying drawings, in which the various parts are designated by suitable reference characters, and in which:-

Figs. 1 and 2, when placed end to end, illustrate diagrammatically the apparatus and circuits provided in accordance with the present invention at a typical field station for the control of a single track switch and the signals for governing traflic thereover.

For the purpose of simplifying the illustration and facilitating in the explanation, the various parts and circuits constituting the embodiment of the invention have been shown diagrammatic lly and certain conventional illustrations have been employed, the drawings having been made more with the purpose of making it easy to understand the principles and mode of operation, 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, instead of showing all of the wiring connections to these terminals.

The symbols and are employed to indicate the positive and negative terminals respectively of suitable batteries, or other sources of direct current; and the circuits with which these symbols are used, always have current flowing in the same direction. The symbols (13+) and (3-) indicate connections to the opposite terminals of a suitable battery, or other direct current source which has a central or intermediate tap designated (CN); and the circuits with which these symbols are used may have current flowing in one direction or the other depending upon the particular terminal used in combination with the intermediate tap (CN) Communication system in generaZ.A centralized trafiic control system in which the present invention is more particularly useful, consists of a control ofiice and a large number of outlying field stations. Communication is established be tween the control oflice and the field stations for the transmission of controls for governing the traflic controlling devices at such stations and for the transmission of indications to give the operator in the control ofiice information as to the location of trains and the response of the various trafiic controlling devices. This communication is established over a station selective coded type communication system in which a small number of line Wires is employed and in which the selective communication between the control ofiice and any particular field station either for the transmission of controls and/or the transmission of indications is established by the transmission of suitable codes.

For the purpose of illustrating the present invention, it is considered unnecessary to illustrate the apparatus in the control omce for impressing a plurality of series of different code combinations to a line circuit in accordance with the positions of code jumpers and control levers, and to illustrate the reception of code combinations of impulses from the field stations, but it is assumed that a system for these purposes may be of any suitable character, such for example as shown in the application of T. J. Judge Ser. No. 613,353, filed May 25, 1932.

It is considered sufficient for an understanding of the present invention to merely illustrate how the composite route control code part of each series of impulses applied to the line circuit results in the control of the trafiic governing devices at a particular station, and to indicate the relation of the apparatus shown with the rest of the apparatus of a complete system.

With reference to the accompanying drawings, a control cflice has been merely indicated by a dotted rectangle as connected to the field station illustrated in Figs. 1 and 2 by three line wires including a control line wire iii, an indication line wire l2, and a common return line wire it, it being assumed that these line wires extend from the control ofiice to each of the outlying field stations of the system. The control line wires together with the common return line Wire are so employed as to complete two line circuits, namely, a control line circuit and an indication line circuit. The control line circuit is for the transmission of impulses from the control office of selected polarities and includes at each field station a three position polarized biased to neutral line relay F.

The transmission of a series of distinctive impulses over the control line circuit results in the step-by-step operation of a stepping relay bank at each field station, irrespective of the character of the impulses; while the character of the impulses determine the particular field station to be selected. A station selecting relay S0 at each field station is energized at the beginning of each cycle of operation and remains selectively energized during the first part or station selecting part of the cycle, so long as the code combination of impulses on the control line circuit corresponds with the code combination assigned to the corresponding field station, but when the code combination of impulses does not correspond with the code combination of a field station, the station selecting relay S0 at that station is deenergized thereby rendering inefiective the succeeding impulses of the series of impulses for that cycle. At the particular station where the relay S0 is selected, that is, still energized at the end of the station selecting part of the cycle, the remaining impulses of the cycle are effective to establish the proper control conditions.

Similarly, for the transmission of indications to the control oflice, only one field station is rendered effective to transmit over the indication line circuit during any particular operating cycle. That particular field station, which is rendered efiective, is selected by means of some suitable lock-out arrangement or superiority of code type of system. In any event, this selection of a field station for permitting it to transmit indications is made effective at such field station by the continued energization of its selecting or lock-out relay LO throughout such cycle of operation, but the detail circuit arrangements and method of operation for the transmission of indications has been considered as immaterial for an understanding of the present invention.

Field station apparatus.'The field station in cludes, besides a line relay F, a neutral line repeating relay FP of the quick acting type which is energized each time the line relay F is energized, irrespective of the polarity of such energization, and is deenergized each time the line relay F is deenergized.

A slow acting neutral relay SA is picked up at the beginning of each cycle of operation and is dropped at the end of each cycle of operation although it is energized only during the successive energizations of the control line circuit as repeated by the relay FP. This is because the relay SA is provided with such slow acting characteristics that its contacts remain in picked up positions during the time period between successive impulses applied to the control line circuit. The slow acting relay SA is also preferably slow acting in picking up, although its drop away time is relatively much longer than its pick-up period.

The field station includes a selecting relay SO which is energized whenever the field station is selected for the reception of controls, as pre viously mentioned; and similarly a lock-out relay LO which is energized whenever the station is selected for the transmission of indications, as previously mentioned.

The field station includes a stepping relayv bank which takes one'step for each'deenergized condition of the control line circuit, but only those relays of this bank, which are operated after the station is selected, have been illustrated, such for example as stepping relays 3V, 4V and 5V. Although the stepping relays have been indicated as being picked up during the deenergized periods of the control line circuit, so that the-energized condition of the control line circuit .may be directly executed or stored on each step, it is to be understood that these operations might be reversed so that the steps could be taken during the energized periods of the control line circuit with the character of the energizations executed or stored during their following deenergized periods.

The field station includes two neutral code receiving relays for each code receiving step taken by the stepping relay bank. For example, the code receivingrelays IPC and INC are positioned when the relay 3V is picked up; the code receiving relays 2P0 and 2N0 are positioned while the stepping relay 4V is picked up; and, similarly any number of code receiving relays can be positioned upon additional steps. The positive code receiving relays PC respond only to positive impulses applied to the control line circuit; while the negative code receiving relays NC respond only to negative impulses applied to the control line circuit. Thus, only one of the two code receiving relays for each step may be positioned or picked up during that step.

. Although the field station is illustrated as including but a single track switch TS, it is to be understood that any number of track switches may be similarly controlled at a field station. The track switch. TS is operated from one extreme locked position to the other by a suitable switch machine SM, which may be of any suitable type known to those skilled in the art.

Associated with the track switch TS and the switch machine SM is preferably a switch box or point detector contacts (not shown) for controlling a switch position repeating relay WP. This switch repeating relay WP is of the polarneutral type, which is energized with one polarity when the track switch TS is in one position and locked, but is energized with the opposite polarity when the track switch is in the opposite position and locked, and deenergized whenever the track switch TS is unlocked or is in operation.

Suitable signals lA-lB and 2A-2B are provided for governing trafiic over the track switch according to the usual practices. Although these signals have been illustrated as color light signals, they may be of any other, suitable type governed in accordance with the present invention. These signals are normally at stop but are cleared whenever their corresponding signal control relays lAG--lBG and 2AG-2BG are energized, subject to the usual automatic block signaling protection. Such block signal control has been indicated in the drawings by the provision of home relays IH and 2H. It is of course, understood that the home relay IE is governed in accordance with traffic conditions in advance of the signal IA; while the home relay 2H is governed in accordance with trafllc conditions in advance of the signals 2A and 2B, all of which has been disclosed in prior applications, such as for example in the patent of S. N. Wight, Patent No. 2,082,436, dated June 1, 1937.

The track switch TS also has associated therewith the usual closed circuit detector track section having the usual track battery and track relay T. A slow acting relay TP is provided for directly repeating the track relay T for purposes hereinafter pointed out.

For the purpose of controlling the operation of the switch machine SM, two switch machine control relays WN and WR. of the neutral type have been provided. These relays'have stick circuits each including a back contact of the other so that only one of these relays will be maintained energized at any one time. If both of these relays are energized, or if both relays are deenergized, the control circuits for the switch machine are so arranged that there is no resulting control. On the other hand, with the relay WN energized, the normal operating wire is energized, thereby causing the switch machine SM to operate the track switch TS to a normal locked position; and similarly, with the relay WR energized, the reverse operating wire is energized, thereby causing the switch machine SM to operate the track switch TS to a reverse locked position.

The direction of trafiic over the track switch is determined by the direction control relays LD and RD, only one of which may be picked up at' any one time. The particular route for the direction selected by these relays is determined by the position of the track switch TS in correspondence with the switch control relays WN and WR, as more specifically pointed out hereinafter.

As previously mentioned, it is contemplated that indications of the positions of the various traflic controlling devices as well as the locations of trains along the trackway may be transmitted to the control oflice, all of which has been omitted for the sake of simplicity in the disclosure of the present invention. Such features are merely indicated on the drawings by suitable legends.

Also, a change relay CH is provided to register whenever a change in indication conditions occur. This change relay is illustrated more for the purpose of showing how it may be made responsive to a particular code call received over the control line circuit for causing the indications at that station to be rechecked so to speak, than for the initiation of the system for the transmission of indications from this field station, as indicated on the drawings by a suitable legend.

Various other apparatus and devices for the field station include bus wires and circuit connections, suitable overload protection, terminal blocks, and such other devices as may be necessary to be employed in actual practice, the illustration being made more with the idea of disclosing the novel features of a system embodying the 4 present invention.

It is believed that further characteristic functions and features of the present invention will be best understood'by considering various typical operations of the present embodiment.

Operation For the transmission of controls a plurality of distinctive code combinations are applied to the control line circuit in the control office, each code combination comprising a plurality of distinctive impulses. In the present disclosure, these impulses are distinctive by reason of their polarity.

The first part of each different series forms a combination that may be termed a station code call for the selection of a particular station; while the latter part of each different series forms a composite route control code transmitted for that station designated by the station code call part of the series. Thus. the composite route control codes for the several stations differ only with respect to their different functions at the several stations, but are designated for the several stations by reason of the preceding station selecting code call. Thus, consideration of the station code calls will be given only general mention, while detailed consideration will be given the composite route control code part of each different series.

With the possibility of having either a positive or a negative impulse for each step, the number of codecombinations is equal to two (2) raised to the power of the number of steps. Each one of these combinations forming a. composite route control code is assigned to the control of a particular route. In the present illustration, three steps have been employed for the composite route control codes, and with the impulses for these three steps arranged in code combinations, eight different codes may be formed as illustrated in the table given below.

Table of composite route control codes Code First Second Third number step step step Code use Switch normal signals stop.

+ Switch normal signals east.

+ Switch normal signals west.

+ Switch normal recheck indications.

Switch reverse signals stop.

Switch reversesignals east.

Switch reverse signals west.

Switch reverse recheck indica tions.

More specifically, there is a group of control levers in the control oflice for each field station. The positioning of the control levers for a particular station followed by the actuation of suitable means to initiate the system, causes the transmission of a series of impulses comprising the code call for that station and the composite route code to select the route at the selected station.

Following the transmission of the station code call, the composite route code is impressed upon the control line circuit, which particular combination is determined in accordance with the composite or combined positions of the control levers for the particular station. In the example chosen, it is assumed that there is a signal control lever and a switch control lever, thus requiring three successive impulses to make the required route combinations as illustrated in the above given table of composite route control codes. It is assumed that these codes are transmitted when the control levers are in proper positions to give the desired controlling conditions at the field station as assigned to each code combination in the table. For example, if the switch lever is in a normal position and the signal lever is in an east clearing position, the second code would be transmitted consisting of to position the track switch TS in a normal position and to clear the eastbound signal lA.

Also, the route codes include a recheck code which is transmitted when suitable means in the control office (in addition to the control levers) is actuated. For example, in the present embodiment, it is assumed that when this recheck lever or other means is actuated, that the fourth route code will be transmitted with the switch lever in its normal position and the eighth code will be transmitted with the switch lever in its reverse position. The purpose of these recheck codes,

as more specifically explained hereinafter, is to cause the field station to retransmit its indications so that the operator may be advised of the actual conditions then existing at the field station.

Station selection andstep-by-step operation. At the beginning of a cycle of operation, the relay FP is energized by polar contact 20 in either a right or a left hand position depending upon the polarity with which the line relay F is energized. The closure of front contact 2| of relay FP energizes the slow acting relay SA, which after a time picks up and remains picked up throughout the cycle of operation until the control line has been deenergized at the end of such cycle for a predetermined period of time.

Also, upon the first impulse of the cycle, the relay S0 is picked up and is selectively held depending upon the following impulses, which, if they are arranged in a particular combination for this station, are effective to maintain the relay SO energized throughout the cycle of operation. Upon the first deenergization of the control line as repeated by the relay FP following the first energization, the relay SA being picked up, the first stepping relay is picked up, and similarly during each following deenergized condition of the control line circuit a succeeding stepping relay is picked up, so that after the station has been selected by the continued energization of the relay SO during the station selecting steps, the control steps are then taken including the stepping relays 3V, 4V and 5V. Thus, five stepping relays, for example, furnish a sufficient number of local channel circuits for the reception of six impulses.

Reception of composite route codes.Assuming that the stepping relays are suitably picked up during the deenergized period following each impulse, then the polarity of the next impulse for each step is efiective to pick up one or the other of the code receiving relays for that step. For example, if the first impulse of a route control code is positive, the positive code receiving relay IPC will be energized; while if the first impulse of a route control code is negative, the negative code receiving relay INC will be energized. i i

More specifically, assuming the impulse to be positive with the stepping relay 3V picked up, the relay IPC is energized by a circuit closed from through front contact 22 of relay SO, wire 23, polar contact 24 of relay F in a right hand position, wire 25, back contacts 23 and 21 of stepping relays 5V and 4V respectively, front contact 28 of relay 3V, wire 29, lower winding of relay IPC, to

On the other hand, assuming the impulse to be negative with the stepping relay 3V picked up, the relay INC is energized by a circuit closed from through front contact 22 of relay SO, wire 23, polar contact 24 of relay F in a left hand position, wire 30, back contacts 3| and 32 of stepping relays 5V and 4V respectively, front contact 33 of relay 3V, wire 34, lower winding of the relay INC, to

The picking up of the contacts for either the relay IPC or the relay INC closes a stick circuit for that relay, which circuit is maintained closed until the end of the cycle of operation. For example, the stick circuit for the relay IPC, when picked up, is closed from through front contact 22 of relay SO, wires 35 and 36, front contact 31 of relay IPC, wire 38, upper winding of relay IPC, to

A similar stick circuit is closed for each of the other code receiving relays when they are once picked up during a cycle of operation. 7

In a similar manner, either the relay ZPC or the relay 2N0 is energized with the stepping relay 4V picked up depending upon whether the next impulse upon the control line circuit is positive or negative respectively.

In other words, at the beginning of each cycle of operation all of the code receiving relays are deenergized, but as the route control code is received, one relay of a pair of relays for each step is picked up on the corresponding step depending upon the character of the impulse for that step.

Execution of route. code.--When a code receiving relay for each step has been properly positioned and the last step is taken during the deenergized period of the control line circuit preceding the application of the last or executing impulse of the cycle, the switch control relays are positioned or governed in accordance with the positions of their respective code receiving relays, as set up by the code impulses, just received.

With the system in normal at rest conditions, one or the other of the switch control relays WN 'or WR is energized through its stick circuit. For

example, if the control received on a previous operating cycle was a normal control, the relay WN is maintained (as shown) energized by a stick circuit closed from through back contact 39 of relay WR, wire 49, front contact 4| of relay WN', wire 42, lower winding of relay WN, to On the other hand, if the control received on a previous operating cycle was a reverse control, the relay W'R would be maintained energized by a stick circuit closed from through back contact 4! of relay WN, wire 46, front contact 39 of relay WR, wire 43, lower Winding of relay WR, to

Returning to the cycle of operation under consideration, if the code receiving relay IPC has been picked up, then upon the last step, the switch control relay WN is energized by a circuit closed from through front contact 44 of relay 5V, wires 45 and 46, back contact 41 of relay lNC, wire 48, front contact 49 of relay IPC, wire 55, upper winding of relay WN, wires 5! and 52, back contact 53 of relay LD, wire 54, back contact 55 of relay RD, to Thus, the normal switch control relay WN is merely maintained energized when its corresponding code receiving relay IPC is picked up. However, the relay WN may be initially picked up by such energization.

On the other hand, if the relay INC has been picked up, then the switch control relay WR is energized bya circuit closed from ,through front contact 44 of relay 5V, wire 45, back contact 49 of relay IPC, wire 48, front contact 41 of relay INC, wire 55, upper winding of relay WR, wires 51 and 52, back contact 53 of relay LD, wire 54, back contact 55 of relay RD, to The picking up of the contacts of the relay WR opens the stick circuit for the relay WN at back contact 39, and as soon as the contacts of the relay WN assume deenergized positions, the stick circuit for the relay WR is closed through front contact 39 of relay WR and back contact 4| of relay WN;

With the switch machine control relay WN picked up andthe switch machine control relay WR deenergized, the normal operating wire 60 of the switch machine SM receive-s energy from through front contact 6| of relay WN and back contact 62 of relay WR; while with relay WR picked upand relay WN deenergized, the reverse operating wire 63 of the switch machine SM receives energy from through front contact 62 of relay WR and back contact 6| of relay WN. With both of the relays WN and WR either energized or deenergized, neither operating circuit of the switch machine can be closed.

This positioning of the switch machine control relays WN and WR causes positive potential to be applied to the operative circuits of the switch machine SM subject of course to suitable approach and detector locking (not shown)-in accordance with the usual practices, thereby allowing the track switch TS to be operated to a new position only under safe conditions.

With the relays WN and WR positioned in accordance with the positions of the code receiving relays 51C and INC respectively, then upon the application of the last or executing impulse of the 'cycle of operation (third in this case), the direction relays RD and LD are positioned in accordance with the positions of their respective code receiving relays ZPC and 2N0, depending upon the polarity of the execution impulse.

With reference to the code table given above, it can be seen that the first impulse of the route code on the first control step, if positive, causes the switch to assume normal positions, and, if negative, causes the switch to assume reverse positions. Likewise, the character of the impulses on the second and third steps determines the character of the signal control. If the character of the second impulse is positive, the signals may be either cleared for an east direction or put to stop depending upon the character of the last impulse; while if the character of this second impulse is negative, then the signals may be either cleared for a west direction or the indications at the station may be re-checked depending upon the character of the last or third impulse, which will be readily apparent from the table of codes.

The various routes set up and the operations which result from the reception of each code can be best explained by considering each code individually. We will consider first, to completethe cycle of operation under consideration, the reception of the second route control code (code No. 2 in the table) which causes the energization of the relays IPC and 2P0, as previously explained. Upon the picking up of the stepping relay 5V, the normal switch control relay WN is picked up in accordance with relay IPC, and the reverse switch control relay WR is left deenergized in accordance with relay INC, as previously explained. Then, upon the application of the last impulse, which is negative for this code, the right or east direction relay RD is energized by a circuit closed from through front contact 22 of relay SO, wire 23, polar contact 2d of relay F in a left hand position, wire 38, front contact 3| of relay 5V, wires 69 and 10, back contact 1! of relay INC, wire 12, front contact 13 of relay iPC, wire 14, back contact 15 of relay WR, wire 76, front contact T! of relay WN, wires 18 and 68, back contact 19 of relay ENC, wire 80, front contact 8| of relay ZPC, wires 82 and 83, back contact 84 of relay LD, wire 85, lower winding of relay RD, to As soon as the contacts of the relay RD respond to such energization, a stick circuit is closed for this relay from through front contact 85 of relay T,' wires 81 and 88, front contact 89 of relay RD, wires 9!] and 83, back contact 84 of relay LD, wire '85, lower winding of relay RD, to

The picking up of the contacts of the relay RD closes an energizing circuit for the relay I AG dependent of course upon the traffic conditions in advance as indicated by the relay II-I. This circuit is closed from through front contact 9I of relay TP, wire 92, front contact 93 of relay WP, polar contact 84 of relay WP in a right hand position, wires $5 and 96, windings of relay IAG, wire 91, front contact 98 of relay II-I, wire 99, front contact II of relay RD, wire I02, back contact I63 of relay LD, wire I04, front contact I05 of relay WN, wire IIIE, back contact I01 of relay WR, to

The energization of the relay IAG closing front contact I88 in combination with the position of the polar contact I99 of the relay IH causes the clear or caution indication of the signal IA to be displayed, so that traffic may pass in an eastbound direction over the track switch TS in a normal position. It is of course to be understood that all of the signals IAIB and 2A2B normally display stop or danger indications.

The passage of an eastbound train over the detector track section associated with the track switch TS in acceptance of the cleared signal IA deenergizes the track relay T which opens front contact IIii deenergizing the track repeating relay TP thereby closing back contact III. The sequential deenergization of the relays T and TP momentarily opens the stick circuit for the relay RD, so that the relay RD assumes a deenergized position.

The opening of front contact SI of relay TP as well as the opening of front contact IUI of relay RD deenergizes the relay IAG causing the signal IA to indicate stop by the closure of back contact I08. In this connection, it will be noted that the closure of back contact III of relay TP prepares the stick circuit of the relay RD so that the relay RD will be stuck up if it is again picked up by the reception of its route code, and will be maintained even upon the sequential picking up of the relays T and TP.

End of operating cycZe.-In the above description, the return to normal of the communication part of the system has not been considered, but the completed control operation has been pointed out instead. Returning to the operation of the communication part of the system, the execution or last impulse, in this case considered to be the sixth of the operating cycle, is applied for the usual period of time for an impulse, after which the control line circuit is deenergized for a prolonged period of time, so that the relay SA at each field station returns to a deenergized position.

The dropping away of the relay SA causes the stepping relays to be deenergized and also the deenergization of the selecting relay S0. The deenergization of the relay S0 at the end of a control cycle causes the stick circuit for the code receiving or registering relays IPC, INC, ZPC and 2N0 to be opened, so that they are returned to normal deenergized conditions in readiness for the reception of the next route code. However, it may be well to point out that, although the code receiving relays do return to deenergized positions, the direction relays LD and RD and the switch machine control relays WR and WN remain in their last actuated positions until again acted upon. In other words, the switch machine control relays must receive a subsequent control in order to change their relative positions; while the relays LD and RD require either a subsequent manual or automatic control for momentarily opening their stick circuits, as previously pointed out in connection therewith.

Consideration of remaining route codes.-Ilaving considered the manner in which the code receiving relays IPC, INC, 2PC and 2NC are positioned during a cycle of operation in accordance with the code received, and the specific manner in which controls result from the execution of route code No. 2, the execution of the remaining codes may be taken up individually with the conditions established prior to the execution impulse being merely mentioned.

For example, the route code No. 1 differs from the route code No. 2 only in the character of the last impulse. This code energizes the code re ceiving relays IPC and 2P0 so that upon the picking up of the fifth stepping relay 5V, the switch control relay WN is energized. As this code is employed for putting the signals at stop, we may assume for convenience that the signal IA is clear, as previously explained, with the direction relay RD picked up, then upon the application of the last or executing impulse, the relay RD is differentially energized with respect to its energization through its stick circuit, so that its con tacts assume deenergized or dropped away posi tions. This differential energizing circuit for the relay RD is closed from through front contact 22 of relay SO, wire 23, polar contact 24 of relay F in a right hand position, wire 25, front contact 26 of relay 5V, wires II2 and H3, back contact H4 of relay 2N0, wire H5, front contact I I6 of relay 2P0, wires I I? and I I8, front contact H9 of relay RD, wire I20, upper winding of the relay RD, to

As soon as the contacts of the relay RD drop away by reason of the substantial reduction to zero of the flux in the relay, both the difierential circuit including its front contact H9 and its stick circuit including front contact 89 are simultaneously opened, so the relay RD is insured of remaining deenergized. The dropping away of the contacts of the relay RD opens the pick-up circuit of the relay IAG at front contact IiJI, so that the signal IA is caused to indicate or display a stop indication, assuming that it was cleared.

It will be apparent that this differential circuit for the relay RD is independent of switch positions, so that should the track switch be in a reverse position, the direction relay RD may be put to stop without operating the switch. This is accomplished by the use of route code No. 5, which is the same as the stop route code No. 1 with the exception that the first impulse of the code is negative. But the stop route codes are not dependent upon the character of the first impulse of the code as the execution circuit for the last impulse of each code goes directly from front contact 26 of relay 5V to the code receiving relays 2P0 and ZNC, and does not include contacts of the relay IPC and INC. This arrangement further provides that by the transmission of one or the other of the stop route codes, namely, code No. l or code No. 5, the track switch can be operated from one position to the other without the clearing of a route for the passage of traffic.

The reception of the third composite route control code (code No. 3) results in the clearing of the signal 2A. More specifically, the reception of this code picks up the relays IPO and 2N0, so that upon the application of the last or executing impulse, which is positive in this case, an energizing or pick-up circuit is closed for the direction relay LD from through front contact 22 of relay SO, wire 23, polar contact 24, of relay F in a right hand position, wire 25, front contact 26 of relay 5V, wires H2, I2I and I22, back contact I23 of relay INC, wire I24, front contact I25 of relay IPC, wire I26, back contact I28 of relay WR, wire I29, front contact I30 of relay WN, wires I3I and I32, back contact N6 of relay 2PC, wire I I5, front contact II4 of relay ZNC, wires I33 and I34, back contact I35 of relay RD, wire I36, lower winding of relay LD, to v The picking up of the contacts of the relay LD closes its stick circuit from through front contact 86 of relay T, wires 81 and I31, front 0on tact I38 of relay LD, wires I39 and I34, back contact I35 of relay RD, wire I36; lower winding of relay LD, to

The picking up of the contacts of the relay LD closes an energizing circuit for'the relay 2AG, from through front contact 9i of relay TP, wire 92, front contact 93 of relay WP, polar contact 94 of relay WP in a right hand position, wires 95 and I21, windings of relay ZAG, wire I40, front contact I4l of relay 2H, wire I42, front contact I03 of relay LD, wire I52, back contact IIlI of relay RD, wires I43 and I04, front contact I05 of relay WN, wire I06, back contact I81 of relay WR, to The energization of the relay 2AG causes the signal 2A to indicate proceed or caution depending upon the traffic conditions indicated by the relay 2H, as indicated in the drawings.

The passage of a train over the detector track section in acceptance of the cleared signal 2A causes the relays T and TP to be sequentially deenergized, which results in the momentary opening of the stick circuit of the relay ID. The release of the relay LD deenergizes the relay ZAG at open front contact I03 and puts the signal 2A to stop. Also, the sequential picking up of the relays T and TP maintains the stick circuit of the relay LD prepared in readiness for its energization upon the reception of a proper route code.

The transmission of the signals-at-stop code No. 1 or the signals-at-stop code No. 5 will also cause the release of the relay H) by energizing the relay LD differentially through its upper winding similarly as the relay RD. For example, the circuit is the same up to and including wire II'I, through wire I50, front contact I5I of relay LD, wire I52, upper winding of relay LD, to

The route code No. 4 and similarly the route code No. 8, are recheck codes which cause the change relay OH to be released for starting the system for the transmission of the indications of the conditions of the traffic controlling devices at the field station. The recheck code No. 8 is the same as the recheck code No. 4 with the exception of the character of the first impulse, but the character of the first impulse does not effect the recheck part of the code, and the same execution circuit is established irrespective of whether code No. 4 or code No. 8 is transmitted. This arrangement is provided so that the recheck codes may be transmitted without effecting an operation of the track switch. In other words, the selecting circuit for the recheck code is not dependent upon the position of the relays IPO and INC.

More specifically, this executing circuit is closed upon the application of the last impulse of either code No. 4 or code No. 8, from through front contact 22 of relay SO, wire 23, polar contact 24 of relay F in a left hand position, wire 35, front contact 3I of relay 5V, wires 69, 1B and I53, back closure of back contact I15 starts the system for the transmission of indications in accordance with the positions of the contacts "I and I12 of the relay WP and contact I13 of relay TP, as indicated by the legends on the drawings. Also, the change in position of the relay TP, or the relay WP, or both, causes the momentary deenergization of the relay CH which ilkewise causes the initiation of the system. The feature of the present invention more particularly resides in the control of the change relay CH from. the control office for the purpose of rechecking the indications.

Regardless of how relay CH is released, it is restored when the indications from the field station have been transmitted, as indicated by the energization of the relay L0 during an operating cycle. This restoration circuit for the relay OH is closed between the third and fourth steps. of an indication cycle from through front contact I14 of relay LO, wire I15, front contact I'IG of relay 3V, back contact ill of relay 4V, wires 18 and I52, lower winding of relay CH, to In other words, during a cycle of operation be.-

tween the third and fourth steps in this case,

while the lookout relay L0 is energized, the change relay CH is restored in readiness for another change in indication conditions at the field station or until a recheck code is again received.

The reception of the route control code No. 6 is similar to the route control code No. 2 except that the track switch is reversed by reason of the negative character of the first impulse of the code. More specifically, the relay INC is picked up by the first impulse instead of the relay IPC, thus causing the relay WR to be energized upon the picking up of the stepping relay 5V.

Thus, upon the application of the last or executing impulse, which is negative in this case, the direction relay RD is energized by a pick-up circuit closed from through front contact 22 of relay SO, wire 23, polar contact 25 of relay F in a left hand position, wire 38, front contact 3I of relay 5V, wire 69, back contact 13 of relay IPC, wire l2, front contact 'II of relay INC, wire I80, back contact I! of relay WN, wire 16, front contact 15 of relay WR, wire 58, back contact 19 of relay 2N0, wire 85, front contact 8| of relay ZPC, wires 82 and 83, back contact 84 of relay LD, wire 85, lower winding of relay RD, to Relay ED is stuck up as previously pointed out.

The picking up of the contacts of the relay RD, with the relay WR energized, causes the energization of the relay IBG by reason of a circuit from through front contact SI of relay TP, wire 92, front contact 93 of relay WP, polar contact 94 of relay WP in a left hand position, wires I3! and 82, windings relay iBG, wire 433, front contact I of relay RD, wire I85, back contact I85 of relay LD, wire I81, front contact I51 of relay WR, wire I 66, back contact I05 of relay WN, to This energization of the relay IBG causes the signal IE to indicate proceed by reason of the closure of front contact I88.

The passage of a train over the detector track section causes the deenergization of the relay RD, as previously pointed out putting the signal IE to stop in a similar manner as described for the signal IA. Also the signal IB is subject to manual control, that is, it may be put to stop upon the reception of the stop code, as will be readily apparent.

The route control code No. 7 differs from the route control code No. 3 only in the fact that the track switch TS is in a reverse position and which is set up by the relays INC and WR. The relay ENC is picked up for this code.

Thus, upon the application of the last or executing impulse of the code No. 7 to the control line circuit, which in this case is positive in character, a circuit is established for the energization of the relay LD, from through front contact 22 of relay SO, wire 23, polar contact 24 of relay F in a right hand position, wire 25, front contact 26 of relay 5V, wires H2 and I2I, back contact I of relay IPC, wire I24, front contact I23 of the relay INC, wire I89, back contact I30 of relay WN, wire I29, front contact I28 of relay WR, wire I32, back contact I I6 of relay 2P0, wire I I5, front contact H4 of relay 2NC, wires I33 and I3 3, back contact I35 of relay RD, wire I36, lower winding of relay LD, to The relay LD is stuck up as previously described.

This energization of the relay ID with the relay WR picked up causes the relay ZBG to be energized by reason of a circuit closed from through front contact 9! of relay TP, wire 92, front contact 93 of relay WP, polar contact 94 of relay WP in a left hand position, wires ISI and ISO, windings of relay ZBG, wire ISI, front contact I92 of relay 2H, wire I93, front contact I85 of relay LD, wire I85, back contact I84 of relay RD, wires I94 and I37, front contact I01 of relay WR, wire I06, back contact I05 of relay WN, to This energization of the relay 2BG causes the signal 2B to indicate proceed subject to traflic conditions indicated by relay 2H. This signal 213 is similarly subject to automatic control upon the passage of a train to thereby return it to stop, as well as being subject to manual control by the stop codes No. 1 and No, 5, as will be obvious from the above description.

Summary The system of the present invention provides for the control of the routes over a railway track switch, together with the putting to stop of these routes andtherechecking of the indications associated therewith, by what is conveniently termed composite route control codes. Such control is thus termed because the codes are usually set up by reason of the combined or composite arrangement of the control levers in the control oflice and more particularly because the response of the traffic controlling devices at the field station or the setting up of a route is dependent upon the completion of a proper code.

In the system of the present invention, two neutral code receiving relays are provided for each step, and all of these relays assume normally deenergized positions. Then one or the other of the relays for each step must receive its impulse in order for a completed code to be transferred from the code receiving relays to the function control relays at the end of an operating cycle.

t will be apparent from the drawings and description that if for one reason or another, one

or more code receiving relays fails to be picked up, the execution impulse at the end of the cycle will be ineffective to position either of the direction relays LD and RD. Furthermore, the system is so arranged that the switch control relays will not be positioned in accordance with their respective code receiving relays except, when only one of the code receiving relays is picked up, so that if a short circuit occurs and both relays are picked up, no control results. In other words, the control of the switch is dependent upon the proper energization of its code receiving relays, and an open circuit, or a short circuit, leaving both relays deenergized, or energizing both relays, respectively, does not result in the improper control of the track switch.

Also, the circuits are so arranged that the switch control relays may not be operated to new positions while a signal is clear as governed by the direction relays LD and RD. This is apparent as the relays LD or RD open the circuits for the relays WR and WN at contacts 53 and 55 respectively.

In connection with the control of the direction relays it will be seen that each is interlocked with the other so that only one may be up at any one time. Also, if the switch controls are not properly executed so that the relays WN and WR are in correspondence with the relays I PC and INC, then the direction relays can not be positioned to clear a route.

Another feature of the present invention resides in the manner in which the track switch may be operated by the transmission of a code while the signals are at the same time held at stop. In other words, there are two stop route codes so that the track switch may be operated independently of the putting to stop of the signals and so that the signals may be put to stop independently of the track switch.

Independently of the position of the track switch, a recheck code may be transmitted to cause the system to retransmit its indications. Also, this recheck code can be transmitted independently of the route conditions that are set up. In brief, the transmission of the recheck code does not effect the control of the track switch or the control of the signals. On the other hand, however, the track switch may be operated at the same time that the recheck code is transmitted.

Having thus described a centralized traffic controlling system as one specific embodiment of the present invention, it is desired to be understood that this form is selected to facilitate in the disclosure of the invention rather than to limit the number of forms which it may assume; and, it is to be further understood that various modifications, adaptations and alterations may be applied to the specific form shown to meet the requirements of practice, without in any manner departing from the spirit or scope of the present invention except as limited by the appended claims.

What I claim is:

1. In a centralized traffic controlling system for railroads, a line circuit having a series of time spaced positive and negative impulses of electric current impressed thereon, a biased-toneutral polar line relay included in said line circuit, step-by-step means caused to take one step for each time space in said series of impulses as repeated by said polar line relay, positive and negative code receiving relays for each step except the last, a pick-up circuit for each positive code receiving relay closed on its corresponding step only when said polar line relay is energized with a positive impulse on that step, a pick-up circuit for each negative code receiving relay closed on its corresponding step only when said polar line relay is energized with a negative impulse on that step, a stick circuit for each positive and negative code receiving relay closed whenever a code receiving relay is picked up until the end of said series of impulses upon which such code receiving relay has been picked up, switch machine control means energized in accordance with said positive and negative code receiving relays for the first step upon the taking of the last step by said step-by-step means, and signal control means energized in accordance with the character of the last impulse of said series as repeated by said polar line relay only when said switch machine control means is in correspondence with its respective positive and negative code receiving relays.

2. In combination; a line circuit having a series of positive and negative impulses forming a code combination applied thereto; a three position polarized line relay included in said line circuit;

a bank of stepping relays, one for each of said impulses and each responsive to take its step for a particular impulse of said series irrespective of the character of such impulse; a positive and a negative code receiving relay for each step; an energizing circuit for each positive code receiving relay closed on its corresponding step when said polar relay is actuated to one polar position; an energizing circuit for each negative code receiving relay closed on its corresponding step when said polar relay is actuated to its other polar position; a stick circuit for each of said positive and negative code receiving relays closed during and only until the end of said series of impulses; and means controlled at the end of said series in accordance with the combination of all of said positive and negative relays which are energized by that series.

3. In combination, a switch machine for operating a railway track switch, signals forv governing trafiio over thetrack switch, a line circuit extending from a control office to the track switch and having a single series of impulses applied thereto for controlling both the operation of said switch machine and said signals, switch control means responsive to certain impulses of said series to thereby control said switch machine, signal control means responsive to certain succeeding impulses of said series only when said switch control means has actually responded to its impulses, and means for clearing said signals when said signal control means has responded to. its impulses only if said switch machine has responded to said switch control means, whereby the failure in the reception of an impulse results in the failure to clear one of said signals,

4. In a centralized trailic control system for governing signals associated with a track switch at a distant point from a control oflice, a single stepping and control line circuit extending from the control oflice to the field station, and apparatus at. the field station comprising, a series of stepping relays operated sequentially in response to the energization and deenergization of said line circuit irrespective of: the polarity of such energization, two neutral signal direction control relays each governing the clearing of either of two signals for one particular. direction over the track switch in accordance with its position, means governed by said stepping relays for momentarily energizing one or the other of said control relays depending upon the polarity of the impulses applied to said line circuit, stick circuits for maintaining said control relays energized, a track relay of a track circuit adjacent the switch, a slow acting track repeater relay, and means including said track relay and said track repeater relay for momentarily breaking said stick circuits to deenergize said control relays upon passage of a train until another series of impulses is transmitted.

5. In a centralized trafiic control system for governing the operation of signals associated with a track switch at a distant field station from a control office, a stepping and control line circuit extending from the control ofiice to the field station, two neutral signal direction control relays each respectively governing the clearing of either of two signals inv a particular directionover the track switch depending upon its position, means for selectively energizing said control relays mo.- mentarily in accordance with the polarity ofv the impulses applied to said line circuit at a particular time, a track relay of a track circuit, ad: jacent the track switch, a slow repeater relay directly controlled by said track relay and assuming its energized and deenergized condition. respectively after a time interval following the energ'ization and deenergization of said track relay, and stick circuits for said control relays. each including a front contact of said track relay in multiple with a back contact of said repeater relay, whereby said control relays. are deenen, gized when a train enters the detector track circuit but not when it leaves, and whereby said control relays may be energized while the train is on said track circuit.

6. In a centralized trafiic control system for governing the operation of signals associated with a track switch at a distant field station from a control office, a stepping and control line circuit extending from the control office: to the field station, a neutral relay responsive to the energization of said line circuit irrespective of the polarity of such energization, a series'of stepping. relays controlled by said neutral relay and energized sequentially, a polar line relay in said line circuit, two neutral signal relays respectively governing the clearing of signals in opposite directions over the track switch, an energizing circuit for each of said signal control relays including av contact of a particular stepping relay and a contact of said. polar line relay, a track relay having a detector track circuit adjacent the track switch, a. slow release repeater relay directly controlled by said track relay, and stick circuits for said signal control relays closed only if said: detector track relay is energized or said repeater relay is deenergized.

'7. In a centralized traffic control system for governing the operation of signals at a distant field station from the control office, a single stepping and control line circuit extending fromthe field station to the control ofiice, and apparatus at the field station comprising, a relay responsive to the energization of said line circuit irrespective of the polarity of such energization', a series of stepping relays controlled by said relay and operated sequentially, a polar line relay in said line circuit, a neutral signal control relay,

'means controlled by a particular stepping relay relay is energized, a stick circuit for maintaining said control relay energized, a detector track relay for breaking said stick circuit to cause deenergizaticn of said control relay upon passage of a train, and means for deenergizing said signal control relay Without breaking its stick circuit when said line circuit is energized with the pposite polarity at the time said particular stepping relay is energized.

8. A centralized traiilc control system for governing the operation of signals at a distant field station from a control office by the polarity of impulses applied to a stepping and control line circuit comprising, a group of stepping relays operated one at a time in response to the successive energization and deenergization of said line circuit, twoneutral signal control relays, means rendered eiiective on a particular step of said stepping relays for momentarily energizing on a subsequent step said control relays selectively dependent upon the polarity of energization of said line circuit on such particular step and said subsequent step, stick circuits for maintaining said control relays energized, and a track relay of a track circuit in advance of the signals for breaking said stick circuits upon the passage of a train.

9. A centralized traffic control system operated by time-spaced impulses of a selected polarity and comprising, in combination with a track switch and associated signals, a neutral signal control relay for governing the clearing of a signal governing tramc in one direction over said track switch, a single stepping and control line circuit, stepping relays operated sequentially one at a time in response to the impulses on said line circuit, an energizing circuit for said control relay including a front contact of a particular stepping relay, means responsive to the polarity of the energization of said line circuit for supplying current to said energizing circuit, a stick circuit for said control relay, and means controlled by said stepping relays and responsive to the polarity of energization of said line circuit for deenergizing said control relay.

10. A centralized trafiic control system for governing the operation of a track switch and associated signals at a distant field station from a control office, a single stepping and control line circuit extending from the control ofiice to the field station, a group of stepping relays energized sequentially in response to impulses on said line circuit, a polar line relay in said line circuit, a station identifying relay controlled by said polar line relay, two neutral signal control relays, energizing circuits for said control relays including contacts of said polar line relay, said station identifying relay and said stepping relays, stick circuits for said control relays, and means responsive to the presence of a train for temporarily breaking said stick circuits during the movement of a train into the portion of track protected by said signals, whereby said signal control relays are automatically deenergized by the passage of a train but may again be energized by subsequent energizations of said line circuit even though a train is present.

11. In combination with a railway switch, four signals for governing traffic over said switch, two

switch control relays, means for operating said switch to one position or the other according as one or the other of said switch control relays is energized, two signal control relays, means controlled from a remote point for selectively energizing said switch and signal control relays, four signal relays, one for controlling each of said signals, circuits for each of said signal relays, each including contacts operated in accordance with the position of the track switch and closed only when the route over the switch governed by the associated signal is available, contacts closed only when the route is unoccupied, contacts controlled by each of said signal control relays and other contacts operated by each of said switch control relays and constituting a part of such relays.

12. In a centralized traffic control system for governing the operation of a power-operated switch and its associated signals at a distant field station from a control office, a single stepping and control line circuit extending from the control oifice to the field station, and apparatus at the field station comprising, a neutral relay energized and deenergized in response to the energization and deenergization or" said line circuit irrespective of the polarity of energization, a bank of stepping relays controlled by said neutral relay and operated sequentially one relay being picked up for each deenergization of said neutral relay, a polar line relay in said line circuit, two neutral normal and reverse switch control relays for governing the operation of the power-operated track switch, means for momentarily energizing one or the other of said control relays depending upon the position of the contacts of said polar line relay following the picking up of a particular stepping relay, and a stick circuit for each of said control relays including a back contact or" the other for maintaining each such control relay energized until such other is energized.

13. Field equipment for a centralized traffic control system of the multiple polarized impulse type comprising, a stepping and control line circuit, a group of stepping relays energized one at a time and one for each deenergization of said line circuit, a neutral control relay, circuit means for momentarily energizing said control relay or not dependent upon the polarity of energization of said line circuit next following the operation of a particular stepping relay, a stick circuit for said control relay, a detector track circuit for breaking said stick circuit upon the passage of a train, and means responsive to the polarity of energization of said line circuit for also deenergizing said control relay.

14. A centralized trafiic control system operated by time-spaced impulses of a selected polarity and comprising, in combination with a track switch and associated signals, a neutral signal control relay for governing the clearing of a signal governing trafiic in one direction over said track switch, a single stepping and control line circuit, stepping relays operated se ,ientially one at a time in response to the impulses on said line circuit, an energizing circuit for said control relay including a front contact of a particular stepping relay, means responsive to the polarity of the energization of said line circuit for supplying current to said energizing circuit to energize said control relay in a particular direction, a stick circuit for said control relay for energizing said control relay in said particular direction when it is once picked up, and circuit means controlled by said stepping relays in accordance with the polarity of energization of said line circuit for at times momentarily energizing said control relay in an opposite direction for causing said control relay to drop away.

15. In a centralized trafiic control system for governing from a control oofice the operation of a power operated track switch and its associated signals at a distant field station, a single line circuit extending from the control office to the field station and having a series of time spaced polar impulses impressed thereon with their polarities selected in accordance with the intended control of the switch and its signals, a polar line relay included in said line circuit, step-by-step means controlled by said line relay to take one step for each time space in said series of impulses, a positive and a negative code receiving relay for each step except the last, a pick-up circuit for each positive code receiving relay including a contact closed on its corresponding step and energized when said line relay is energized with a positive impulse on that step, a pick-up circuit for each negative code receiving relay including a contact closed on its corresponding step and energized when said line relay is energized with a negative impulse on that step, stick circuits for said code receiving relays closed until the end of said series of impulses, a normal and a reverse switch control relay for governing the normal and reverse power operation of said track switch, circuit means effective on said last step for energizing the normal or the reverse switch control relay in accordance with the energized condition of said positive or negative code receiving relay for a particular step of said step-by-step means, said circuit control means being ineffective if both code receiving relays for that step are picked up, stick circuits for said normal and reverse switch control relays, the stick circuit for each controlrelay including a back contact of the other control relay for maintaining it energized until the other relay is energized, two signal control relays for selectively clearing said signal, and circuit means causing the energizaton of one or the other of said signal control relays depending upon whether the positive or the negative code receiving relay for another step of said step-by-step means is picked up, said circuit means being efiecti-ve on said last step of said step-by-step means only if said switch control relays are in correspondence with their respective positive and negative code receiving relays, and only if there is but a single code receiving relay picked up for said another step, whereby a signal is cleared only if said series of impulses is completely received by said positive and negative code receiving relays for the several steps.

16; In combination; a single line circuit having any one of a plurality of different series of ries; normally deenergized code receiving relays for each step of said step-by-step means, one for each distinctive character of impulse in said series; circuit means for energizing that particular code receiving relay for each step corresponding to the character of the impulse for that step; stick circuit means maintaining energized those of said code receiving relays which are energized during any series of impulses only until the end of that series; storing relays for storing said code of any series, there being one storing relay for each code receiving relay; circuit means rendered effective at the end of a series of impulses to energize those of said storing relays corresponding to the code receiving relays energized during such series, said circuit means being efiective only if there is only one code receiving relay energized for each step; and stick circuit means for each of said storing relays, said stick circuit means for each storing relay for a given stepof said step-by-step means being deenergized only if another stcring relay for that step is energized; whereby said storing relays remain as energized at the end of the. preceding series of impulses if more than one code receiving relay is energized for any step during a series of impulses just received.

17. In a centralized traffic controlling system for railroads; a single line circuit having a plurality of series of positive and negative impulses applied thereto, each of said series of impulses forming a different code combination; a polar line relay included in said line circuit; step-by-step means operable to take one step in an invariable manner for each impulse of any series; a positive and a negative code receiving relay for each step; circuit means energizing either said positive or said negative code receiving relay for each step depending upon whether said polar line relay is energized with a positive or a negative impulse for that step; means maintaining energized those of said code receiving relays which are energized during aseries only until the end of that series; storing means for storing the code combination of any series received; by said code receiving relays; circuit means for maintaining said storing means energized in accordance with the last code stored until: conditioned in accordance with the code registeredby said code receiving relays during the next succeeding series of impulses; and circuit means efiective for conditioning said storing means in accordance with the code registeredby said code receiving relays only if there is but a single code: receiving relay energized for each step; whereby said storing means fails tobe conditioned in accordance with the code combination of any series if on any step of said step-by-step means for that series both or neither of said code receiving relays is energized.

l8. In a centralized traffic control system of the character described for transmitting controls froma control ofiice over a single line circuit to any selected one of a plurality of field stations, a field station equipment for each of the stations responsive to a series of time spaced impulses of selected polarities including a first group of consecutive impulses of polarities forming a code characteristic of that particular one of said stations and a second group of consecutive impulses of polarities characteristic of the controls for such particular station, said field station equipment comprising a station identifying relay remaining energized at the end of the first group of a series of impulses on said line circuit only if each impulse of that group has a predetermined polarity, a series of stepping relays operated sequentially through a cycle of operation during a series or time spaced impulses one at a time each time said line circuit is deenergized for a time space, a pair of neutral code responsive relays for each of said stepping relays operated during said second group of impulses, means effective only if said station identifying relay is energized for energizing one or the other of the code responsive relays for each pair dependent upon the polarity of energization of the line circuit following the time space which operates the corresponding stepping relay, means for maintaining such code responsive relays as are energized during a cycle of operation of said stepping relays only until the end of such cycle of operation, and control means conditioned near the end of such cycle of operation in accordance with the then existing condition of said code responsive relays.

19. In a centralized traffic control system for governing the operation of signals at a distant field station from a control office by the polarity of a series of impulses applied to a line circuit comprising, a group of stepping relays picked up one at a time and one for each successive deenergization of said line circuit, two neutral code receiving relays, two neutral signal control relays, circuit means eifective on a particular step for energizing one or the other of said code receiving relays dependent upon the polarity of the impulse on said line circuit following the picking up of the stepping relay for that step, stick circuit means for said code receiving relays energized only until the end of a series of impulses, pick-up circuit means efiective on a subsequent step for energizing one or the other of said signal control relays depending upon the particular code receiving relay picked up on said particular step and depending upon the impulse applied during said subsequent step being of a predetermined polarity, a stick circuit for each of said signal control relays for energizing its control relay in the same direction as its pick-up circuit, circuit means effective on said subsequent step if a particular one of said code receiving relays is picked up and if the polarity of the impulse for said subsequent step is opposite from said predetermined polarity for said subsequent step to cause the energization of that particular one of said signal control relays then picked up in a direction opposite to the energization of such relay by its stick circuit, said circult means for each relay including a front contact of that relay, and a track relay of a track circuit in advance of the signals having a contact for also breaking said stick circuits for said signal control relays upon the passage of a train.

20. In a centralized traffic control system for governing the operation of a power-operated switch and its associated signals at a distant field station from a control office, a single stepping and control line circuit extending from the control ofiice to the field station and having different series of polar impulses applied thereto, and apparatus at the field station comprising, a bank of stepping relays operated sequentially through a cycle of operation in response to the energization and deenergization of said line circuit for any series of impulses, switch control means conditioned to govern said poweroperated track switch to the normal or reverse positions depending upon the polarity of energization of said line circuit at the time a particular step relay is operated, signal control means for governing the clearing of signals in opposite directions over the track switch and selectively conditioned in accordance with the polarity of energization of said line circuit at the time another step relay is operated only if said switch control means has been conditioned to correspond to the polarity of energization of the line circuit on said particular step, means preventing a change in the condition of said switch control means while said signal control means is conditioned to clear the signals in either irection, and means controlled by said signal control means for selectively clearing said signals only if said track switch has operated into correspondence with said switch control means.

21. In a centralized trafiic control system for governing from a control office the operation of a power operated track switch and its associated signals at a distant field station, a single line circuit extending from the control omce to the field station and having a series of time spaced polar impulses impressed thereon with their polarities selected in accordance with the intended control of the switch and its signals, a polar line relay included in said line circuit, a stepby-step means controlled by said line relay to take one step for each time space in said series of impulses, a positive and a negative code receiving relay for each step, a pick-up circuit for each positive code receiving relay including a contact closed on its corresponding step and energized when said line relay is energized with a positive impulse on that step, a pick-up circuit for each negative code receiving relay including a contact closed on its corresponding step and energized when said line relay is energized with a negative impulse on that step, stick circuits for said code receiving relays closed only until the end of said series of impulses, a normal and a reverse switch control relay for governing the normal and reverse power operation of the track switch, stick circuit means effective to maintain energized the particular switch control relay to be last energized until the opposite switch control relay is energized, circuit means effective at the end of said series for energizing the normal or the reverse switch control relay in accordance with the energized condition of a positive or negative code receiving relay for a particular step of said step-by-step means, said circuit means being ineffective if both code receiving relays for that step are picked up, a signal control relay, circuit means for effecting the energization of said signal control relay depending upon the energization of a positive or a negative code receiving relay for another step of said stepby-step means, said circuit means being effective at the end of said series of impulses and only if said switch control relays are in correspondence with their respective code receiving relays, and circuit means controlled by said signal control relay for clearing one or the other of the signals depending upon the position of the track switch only if such position of the track switch corresponds to the position required by the normal or reverse switch control relay then energized.

ROBERT F. WELLS.

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