US2113383A - Centralized traffic controlling system for railroads - Google Patents

Description

April 5, 1938. w. T. POWELL CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Filed April 15; 1935 7 Sheets-Sheet 1 mvsmo Z0. .7

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April 5, 193-8. w. T. POWELL I CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Filed April 15, 1933 INVENTOR BY a ATTORNEY 7 Sheets-Sheet 5 ATTORNEY W. T. POWELL CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Filed April 13, 1933 April 5, 193-8.

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April 5, 1938. w. T. POWELL 2,113,383

CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROAI JS Filed April 15, 1935 7 Sheets-Sheet 7 R 5 ATTORNEY 'INVENTO Z0. .7

Patented Apr. 5, 1 938 PATENT OFFICE CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Winfred T. Powell, Rochester, N. Y., assignor to General Railway Signal Company, Rochester, N. Y.

Application April 13, 1933, Serial No. 665,991

25 Claims.

This invention relates to centralized traflic controlling systems for governing traffic over railroads and it more particularly pertains to the communication part of such systems.

In a centralized traffic controlling system of the type contemplated by the present invention, the switches and signals at various points along a railroad system are placed under the control of an operator in a central control ofiice in such a way that the operator may at will change the position of the switches and signals, subject to the safeguards which are customarily provided to prevent unsafe operations. Also, the system provides means whereby indications are displayed in the control ofiice to inform the operator of the presence or absence of trains on the various track sections throughout the territory under his supervision and to indicate the positions and conditions of the various switches, signals and the like.

This invention is particularly useful in such a system which is called upon to carry out a large number of control and indication functions during a short time. A single dispatcher can handle the traffic over a large section of track, so it is apparent that the controls and indications should be capable of transmission at such a high rate of speed that excessive accumulation of stored controls and indications is avoided.

The switches and signals are distributed throughout the territory but those located relatively near or adjacent each other, together with the apparatus provided for their control are conveniently referred to as comprising a field station. The communication system is provided to interconnect the control office with the several field stations and is so organized that the operator obtains complete supervision of the various switch and signal devices at the stations.

In accordance with the present invention, the communication system includes three line wires extending from the control ofiice through the several field stations in series. For convenience in describing the operation of the system, these three line wires are referred to as the N, A and B lines. Line N is the neutral line over which stepping impulses and certain control impulses are transmitted. The A and B'lines serve as the return conductors for the N line and are also used for transmitting certain other control impulses, as well as indication impulses. In other words, line N in combination with lines A and B comprise the stepping line circuit, while lines A and B in combination with line N comprise the message line circuit.

Since the system is of the coded duplex type, it is operable through cycles for the transmission of controls and/or the transmission of indications. The system is also of the diplex type which provides for the transmission of two simultaneous coded control combinations during a cycle of operations for selecting two field stations and for transmitting simultaneous controls t6 these two field stations.

When controls are transmitted to a single station during an operating cycle, a station selecting code is first applied to the line for selecting the particular station desired, after which the controls are transmitted to the selected station by means of code impulses. When controls are transmitted to two stations during a single cycle, two station selecting codes are simultaneously applied to the line for selecting the two particular stations desired, after which the controls are transmitted to these selected stations by means of simultaneous code impulses.

When indications are transmitted, the field station transmitting such indications first sends a station registering code for registering that Sta-- tion in the control office. ular indications are transmitted from the registered station to the control office by means of an additional code and are displayed on indicator devices, such as lamps or the like associated with the transmitting station.

For the transmission of controls, a predetermined number of impulses of selected polarities is placed on the stepping line circuit. The apparatus at the control ofiice and at the field stations operate through a cycle of operations, irrespective of the polarities of the impulses, while the distinctive polarities of such impulses determine the particular'station to be selected and the controls to be transmitted thereto. During the transmission of a predetermined number of impulses over the stepping line circuit for selecting a station, an additional station may be selected by the distinctive polarities of the impulses which are applied to the message line circuit. Inother words, the stepping operation during a cycle is controlled over the stepping line conductor N with station selection and the transmission of controls to selected stations controlled independ ently over line N and over the message lines A and B.

If a single station is to be selected which responds to distinctive polarities applied to the message line circuit, then the impulses applied to the stepping line circuit are used for stepping purposes only and are all of the same polarity.

Thereafter the partic- If a single station is to be selected which responds to a distinctive code applied to the stepping line circuit, then the impulses applied to this circuit control the stepping operations and by virtue of their polarities, control the selection of the desired station. Under this condition, the current impulses applied to the message line circuit in the control oifice serve no useful purpose and are all of the same polarity.

For the transmission of indications, means are provided to condition the message line circuit during the de-energized periods of the cycle between impulses in any one of three different ways. First, leaving the A and B lines closed; second, opening the A and B line circuit once; and third, opening the A and B line circuit twice. This provides a choice of three code characters for each step.

Obviously, the provision of three distinctive code characters for each step results in obtaining nine distinctive codes where each complete code comprises two steps. Similarly, twenty-seven distinctive complete codes are obtained where each complete code comprises three steps. In other words, the number of indication code combinations obtained is equal to three raised to the power of the number of steps.

Other objects and advantages of the present invention will be hereinafter set forth in the specification and claims and shown in the drawings. The characteristic features will be explained more in detail in the following description of one embodiment of the invention, while various other characteristic features and advantages of the system will be in part pointed out and in part apparent as the description progresses.

For convenience in describing the operation of the system, the energized periods of the stepping line circuit will be referred to as the on periods while the de-energized periods which separate the on periods will be referred to as the off periods.

In describing the invention in detail, reference will be made tothe accompanying drawings which illustrate in a diagrammatic manner the apparatus and circuits employed. Those parts having similar features and functions are designated in the different figures by like letter reference characters, generally made distinctive either by the use of distinctive exponents representative of their location or by the use of suitable prefix numerals representative of the order of their operation and in which:-

Fig. 1 is a diagrammatic showing of the threewire line circuit extending from the control ofiice through a typical intervening field station to an end field station;

Fig. 2 illustrates the interlocking circuits of the storing, storing repeating and code determining relays located in the control office and assoc ated with four field stations;

Figs. 3A, 3B, 4A and 4B illustrate the apparatus and circuits employed at the control ofiice;

Fig. 5 illustrates a portion of the apparatus and circuits employed at a typical even field station;

Fig. 6 illustrates an additional portion of the apparatus and circuits associated with the typical even field station illustrated in Fig. 5, together with a small part of the apparatus and circuits employed at a typical odd field station.

In tracing the detailed circuits, Fig. 4A should be placed below Fig. 3A, Fig. 4B should be placed below Fig. 3B, and to the right of Fig. 4A, Fig. 6

should be placed below Fig. 5, and Fig. 5 should be placed to the right of Fig. 3B, with correspondingly numbered lines in alignment.

General description The general plan of operation of the system may be best understood by referring to Fig. 1, which illustrates the fundamental line circuits extending from the control office through one intervening field station to the end field station. Two line batteries are used in the control office for controlling the stepping operations and for the transmission of controls. Battery NB is conveniently referred to as the neutral battery, since it is applied to the neutral line N for impulsing and for transmitting controls to those stations which have their controls effected through the medium of the N line. Battery AB is used for transmitting to those stations whose controls are effected over the A and B line conductors. Battery AB has a center tap X which is connected to line N through battery NB when the system is going through a cycle of operations.

Assuming that relays STR and EPC are picked up and that relays ENC and 0C are de-energized, a circuit may be traced for energizing line N which extends from the terminal of battery NB, front contact 20 of relay STR, front contact 2I of relay EPC, back contact 22 of relay ENC, winding of relay IF, back contact 23 of relay EP, N line conductor 24, winding of relay IF line conductor 25, winding of relay IF line conductor 26, front contacts 21 and 28 of relay SA (relay SA will be picked up as will be later described), to both the A and B line conductors in the direction indicated by the dotted line arrows. The current will divide and partly return by way of the B line conductor 3|, upper winding of relay 2F conductor 32, upper winding of relay 2F conductor 33, back contact 9 of relay 00, upper winding of relay 2F, through the upper portion of battery AB to terminal X, back contact 34 of relay ENC, front contact 35 of relay EPC, and front contact 36 of relay STR to the terminal of battery NB.

Again referring to the end field station, as mentioned above the current divides and another portion of the current flows through A line conductor 3'! in the direction of the dotted line arrows, back contact 38 of relay P lower winding of relay 2F conductor 39, back contact 40 of relay P lower Winding of relay 2P conductor 4|, back contact I4 of relay 0C, lower winding of relay 2F, through the lower portion of battery AB to terminal X and thence to the terminal of battery NB over the remainder of the circuit previously described.

Current in the above assumed direction applied to line N is effective to position line relays IF, IF and I F to their right hand positions. It is obvious that the reversal of current flow from battery NB, by relay ENC being picked up and relay EPC being down, is effective to position line relays IF, IF and IF to their left hand positions. Therefore, the selective operation of relays EPC and ENC effect the selective operation of the polar relays connected in the neutral line N.

Referring to the dotted line arrows (battery NB current) associated with relays 2F, 2F and 2F it will be noted that the current flow through the two windings of each of these relays is in the same direction. The upper and lower windings of each of these relays are either oppositely wound or the wires leading to the terminals of one winding are reversed with respect to the wires leading to the other winding, either of which expedient results in the 2F relays (with suitable exponent) not being affected by the currents above mentioned and being properly operated by current flowing in line conductors A and B in series as will be later described.

Since the reversal of the current in line N results in a current flow in opposition to that indicated by the dotted line arrows at all points, it will be apparent that the same relation exists with respect to the 2F relay windings just mentioned, because the reverse in direction through one winding of each 2F relay is accompanied by a similar reverse in direction through the other winding of the same relay. BriefiyQline N may be impulsed with or impulses from battery NB to effect the positioning of the IF relays to the right or left respectively, without adversely affecting any of the 2F relays.

Referring now to the full line arrows which indicate the current flow when the A and B line conductors are energized from battery AB. This energizing circuit may be traced from the terminal of battery AB, lower winding of relay 2F, back contact M of relay 0C, conductor 4|, lower winding of relay 2F back contact 40 of relay P conductor 39, lower winding of relay 2F back contact 38 of relay P conductor 31, front contacts 28 and 21 of relay SA conductor 3!, upper winding of relay 2F conductor 32, upper winding of relay 2F conductor 33, back contact 9 of relay OC and upper winding of relay ZF, to the terminal of battery AB; The full line arrows indicate that the current flow through the upper windings of the 2F relays is in opposition to the current flow through the lower windings of these relays and it follows from the above discussion relating to the direction of the windings of these relays or their terminal connections, that the magnetic flux in the two windings aid.

It will be assumed that current flowing through the lower windings of the 2F relays from left to right and through their upper windings from right to left, is efiective to position these relays to their right hand positions. By picking up relay 00, the direction of current fiow over the above described circuit is reversed and since this reversal affects both windings of the 2F relays alike, the full line arrows will be assumed transposed to indicate this condition, with the result that both windings of the 2F relays are energized in aiding relation, so that these relays actuate their contacts to the left hand positions.

A brief statement of the four conditions of energization of the three line conductors is as follows:

First, line N energized with potential from battery NB, line A energized with potential from battery AB and line B energized with potential from battery AB results in a current flow from battery NB through the IF relays from left to right. The current from the upper portion of battery AB through line N is in series aiding relation with the current from battery NB, while the current flow from the lower portion of battery AB through line N is of opposite sign, with the result that the IF relays are positioned to the right.

Second, reversing the connection of battery NB to line N places battery NB and the lower portion of battery AB in series aiding relation, while the current from the upper portion of battery AB is opposite in sign from both other battery units,

with the result that the IF relays are positioned to the left.

The third condition is the same as the first with the connection of battery AB to lines A and B reversed, which results in the IF relays being positioned to the right because again the'upper portion of battery AB aids and the lower portion opposes battery NB.

The fourth condition is the same as the second with the connection of battery AB to lines A and B reversed, which results in the IF relays being positioned to the left because again the lower portion of battery AB aids, While the upper portion opposes battery NB.

These four conditions effect the proper operation of the 2F relays because, under the first condition currents from battery NB and the upper portion of battery AB combine and flow through the upper windings of the 2F relays (on line B) from right to left, which positions these relays to the right. Under the second condition, currents from battery N13 and the lower portion of battery AB combine and flow through the lower windings of the 2F relays (on line A) from left to right to position these relays to the right. Under the third condition, currents from battery NB and the upper portion of battery AB combine and flow through the lower windings of the 2F relays (on line A) from right to left, which positions these relays to the left. Under the fourth condition, currents from battery NB and the lower portion of battery AB combine and "flow through the upper windings of the 2F relays (on line B) from left to right to position these relays to the left.

This discussion relating to the 2F relays does not refer to the 2F relay in the control office, since this is not a polar relay. Under the four conditions discussed, the currents which combine in a winding of a 2F relay predominate over the current through the other winding of the same relay, which is either of comparatively low value or entirely neutralized by the current fiow from the two battery units in opposition. It is therefore apparent that conditioning the A and B line conductors by applying and polarities from battery AB thereto'does not interfere with the conditioning of the N line conductor by battery NB. Further, these two circuits may be simultaneously conditioned without interference, so that controls may be transmitted simultaneously over the 3 wire circuits indicated in Fig. 1 to two different field stations.

It will be understood that additional stations connected in the line, either between the control ofiilce and the intervening field station or between the intervening field station and the end field station, have their line circuits arranged the same as the intervening station shown in Fig. 1. As will be more specifically pointed out, the points of difference in the circuit connections at different field stations are the distinctive connections of the code jumpers, which so condition the circuits that a particular field station will be fully responsive only to the particular code assigned to that station.

For the purpose of simplifying the drawings, certain conventional illustrations have been employed which are used more with the idea of making it easy to understand the principles and mode of operation, rather than with the attempt of illustrating the specific construction and arrangement of parts and circuits that conventional manner, the use of symbols being employed to indicate the connections to the terminals of batteries or other sources of current instead of showing all of the wire connections to these terminals.

The symbols and indicate the positive and negative terminals respectively of suitable batteries or other sources of current and the circuits with which these symbols are used always have current flowing in the same direction. The symbols (B+) and (B-) are employed to indicate the positive and negative terminals respectively of a suitable battery or other source of current having an intermediate tap (CN). and the circuits with which these symbols are used may have current flowing in one direction or the other, depending upon whether the terminal (B+) or (B) is used in combination with the intermediate tap (CN).

No attempt has been made to show all of the apparatus employed, such as the total number of manual controls at the control ofiice, the total amount of equipment or its exact arrangement at the field stations since this apparatus and equipment may vary to suit local conditions. The character of that apparatus illustrated in the typical control office and at the typical field station will now be considered.

Control o fice equipment-The control oflice includes a control machine having a group of control levers for each of the field stations, a miniature track layout corresponding to the actual track layout in the field and indicating lamps or equivalent devices, together with ap paratus and circuits to accomplish the desired operation of the system. That part of the control oflice illustrated in Figs. 3A, 3B, 4A and 4B shows more particularly that part of a control machine which is typical of the apparatus associated with a single field station having a track switch, a cross-over or the like, together with the general transmitting apparatus employed for all such field stations.

The apparatus for one track switch comprises a miniature track switch 2ts, a switch machine control lever 2SML, a self-restoring starting button 28B and switch machine indicating lamps NL and RL. Starting buttons ISB, 38B and 4SB illustrated in Fig. 2 and corresponding switch machine levers ISML, 3SML and 4SML illustrated in Fig. 4A are associated with respective field stations, in addition to the No. 2 field station apparatus previously mentioned. Attention is particularly directed to the miniature track switch 215s, starting button 283 and switch machine lever ZSML, because in describing the detailed operation of the system it will be assumed that station No. 2, which corresponds to these devices will be selected and controls transmitted thereto.

Similarly, signal control levers are also associated with the respective miniature track switches and starting buttons, but in order to simplify the drawings and description, these levers have been omitted, since the control of the track switch at station No. 2 may be considered as typical of the control of other types of traflic controlling devices.

The actuation of lever ZSML to one extreme position or the other followed by the actuation of the starting button ZSB, results in the normal or reverse operation of the track switch corresponding to lever ZSML at field station No. 2 illustrated in Fig. 5. The momentary actuation of a. starting button is stored by its associated storing relay ISR, 28R, 38R. or ISR, see Fig. 2. Storing repeating relays ISRP, 2SRP, 3SRP and 4SRP are associated with corresponding storing relays. Code determining relay [2CD is associated with starting buttons ISB and ZSB, while code determining relay 340D is associated with starting buttons 38B and 4SB. Common relay CM cooperates With the bank of storing, storing repeating and code determining relays to deenergize the series pick-up circuit of the CD relays as long as a CD relay is energized.

The control oflice includes a biased-to-neutral polar line relay IF and a neutral line repeating relay FP, both of which are normally deenergized. Slow acting line repeating relays SA and SAP are picked up at the beginning of each cycle and dropped during the change to normal period at the end of each cycle. The releasing or drop-away time of relay SA is sufficiently long so that its contacts remain in their actuated positions during all off periods between successive on periods. During the last 0115 period, which is comparatively long for the purpose of returning the system to normal, relay SA is released and after a predetermined interval of time, its repeating relay SAP is released.

Associated with line relay F and its repeating relays is a bank of stepping relays IV, 2V and 3V,

together with a half step relay VP, which are provided to mark ofi the successive steps of each cycle. An impulsing relay E is jointly controlled by the half step relay and the stepping relays, with the operations of relay E repeated by impulse repeating relay EP, which in turn opens and closes the N line conductor. Relays E and EP also control the pick-up and stick circuits of the indication message relays IM, 2M and 3M, as well as controlling the indication executing circuits, all of which will be specifically pointed out in the detailed description. Line relay 2F, of the neutral type, is for the purpose of controlling the circuits to the message relays IM, 2M and 3M and also to start the system into a cycle of operations in response to a change in condition at a field station.

The polarities of the impulses applied to the stepping line circuit from battery NB on successive steps of a cycle, are determined by positive code sending relay EPC and negative code sending relay ENC. The reference character E associated with these code sending relays indicates that even numbered stations are selected over the line circuit controlled by these two relays. This is merely a typical arrangement used for convenience in describing the operation of the system, since the stations controlled over line N could as well be referred to as odd stations. The polarities of the impulses applied to the message line circuit from battery AB are determined by odd code sending relay OC and for convenience in the description, it will be assumed that odd numbered stations in the system are controlled over the message line circuit.

A starting relay STR is picked up to initiate a cycle of operations, both when controls are to be transmitted to an odd and/or an even station due to the manual initiation of the cycle in the control oflice and when indications are to be transmitted due to the automatic initiation of a cycle by a field station. Field start relay FC is picked up when the cycle of operations is initiated by a field station and oflice start relay C is picked up when a cycle of operations is initiated in the control office.

in Fig. 4A. Pilot relays IPT and ZPT are selectively connected to the indication buses so that they may be positioned on the first step of the cycle when indications are transmitted. Similarly, additional pilot relays (not shown) may be provided for additional steps, up to the point where a sufficient number of codes for station registration is obtained.

Station relays IST and 2ST are provided for registering, in the control office, the station transmitting indications. The conductor indicated indication phantom is not used in this embodiment for connection to a station relay, because when controls aloneare transmitted during a cycle, the system inherently transmits back to the control ofilce an indication code combination which positions relays IPT and 2PT to the left and which code combination does not correspond to a field station.

A choice of three code characters for each. step results in selectively positioning the two pilot relays in three distinctive positions, two of which may be used as indicated. By adding two more pilot relays and conditioning them on the second step, nine different code combinations are obtained, eight of which may be used, with the ninth or phantom combination not being employed.

The control machine also includes suitable indication storing relays HR and ZIR. for storing the indications of whether the associated track switch is in its locked normal position, its locked reverse position, or unlocked, as repeated by a switch repeating relay at the station. Indicator lamp NL is displayed to indicate the locked normal position and indicator lamp BL is lighted toindicate the locked reverse position. Both of these lamps unilluminated is an indication that the switch is in its unlocked position.

It will be obvious that additional indication receiving relays may be provided and connected in the manner typically illustrated by relays IIR and 21R, for receiving and displaying additional indications from a registered field station.

Field station equipment.-The even field sta tion illustrated in Figs. 5 and 6 is typical of all field stations of the system and may be adapted to be used at the first, second or any other location by merely altering certain code jumpers to arrange for the desired codes and by altering certain wire connections to arrange for the distinction between odd and even stations. The end field station differs slightly from the others with respect to contacts 21 and 28 on relay SA. and resistance 313. the purpose of which will be pointed out later in the description. For convenience in the description, the field station illustrated in Fig. 5 and in the portion below the dashed line in Fig. 6, is assumed to be even station No. 2. It will be understood that the equipment and apparatus at all other even field stations are the same as illustrated in connection with the No. 2 station with the exception of the above mentioned code jumpers.

All odd numbered stations, of which station No. l partly illustrated above the dashed line of Fig. 6 is typical, have apparatus and circuits the same as the illustrated even field station, except that the polar contact I86 of relay 2P is used at the odd stations and is not used at the even stations. Likewise, polar contacts similar to E9! of relay IF are not used on corresponding relays at the odd stations. The organization of the different odd station circuits is otherwise the same except for the distinctive connections of the code jumpers.

With reference to Fig. 5, a turn-out track is illustrated as connected to a main track by means of a track switch T8 which is operated from one extreme locked position to the other by a suitable switch machine SW. The switch machine is operated by the two-position polar magnetic stick relay SMR which is in turn controlled from the control ofilce through the medium of the com-' munication system.

Suitable signals are associated with the track switch T8 for governing trafiic thereover and automatic signaling means are provided, interrelating the trafiic over this track switch with such other sections of track and traffic controlling devices as may be associated therewith. These signals are also controlled from the control office through the medium of the communication system by means of control relays operated in a manner similar to the operation of relay SMRF, which operation may be considered typical. For the sake of simplicity, the signals and signal relays are omitted from the present disclosure. The detector track section having a normally closed track circuit with the usual track relay and suitable track battery (not shown), are also associated with the track switch T3 for indicating the passage of trains thereover.

Switch repeating relay WP shown in Fig. 6 repeats the position and condition of track switch TS This relay is of the polar neutral type and is so controlled that it positions its polar contact I98 to the right when the track switch is in its normal locked position and to the left when the track switch is in the reverse locked position. Neutral contacts 200 and 2M are dropped when the track switch is in its unlocked or mid stroke position. It will later be explained how these three conditions of relay WP effect the transmission of indications from this station when it is registered in the control office. It is believed that this explanation will be sufficient to indicate the manner in which similar indications relating to other conditions at the field station may be transmitted, as will be apparent from a discussion of the typical operations effected by the positions of relay WP A quick acting biased-to-neutral polar relay IF repeats the impulses applied to line N. A quick acting biased-to-neutral polar relay ZF responds to the impulses applied to line conductor A. As above mentioned, the polar contacts on this relay are not used at even numbered stations but to make the system symmetrical, it is preferred to make use of the windings of this relay at all field stations. A quick acting line repeating relay FP repeats the energizations and deenergizations of the N line circuit, irrespective of the polarities-pf the energizations. A slow acting relay SA of the neutral type repeats the energized condition of relay F'P and is used to define the bounds of each cycle of operations at the field station, since it is energized at the beginning of each cycle and is not dropped until the change to normal period at the end of the cycle.

A bank of stepping relays IV 2V 3V and the associated half step relay VP is likewise included at each field station. Since these relays operate in a similar manner and in synchronism with the stepping relay bank in the control ofiice, their detailed circuits have not been shown. Conductors 150, WI, [52, I53 and I54 leading to bracket BK correspond to conductors 50, 52, 53 and 54 of Fig. 3B so that it is obvious how the field station stepping relay bank operates in synchronism with the control ofiice bank of stepping relays. Odd station stepping relays IV 2V and 3V shown in the upper portion of Fig. 6 are illustrated for the purpose of indicating the manner in which the 2F relays efiect station selection and control relay operation at odd numbered sta- .tions.

For the purpose of illustrating the selection of a station, station relay S0 is provided. These station relays are picked up at all stations at the beginning of a cycle and as stepping progresses, they are dropped out, one-half of those up being dropped at each step, until only the one associated with the desired station remains picked up after the station selecting steps have been marked off. It is to be understood that any suitable station selecting means may be employed, such as the use of pilot relays and a station relay at each station and still be within the scope of the present invention.

A lock-out relay L0 is provided at each station to determine when a particular station is to transmit new indications. Relay L0 is picked up during the initiating period of a cycle when indications are transmitted and is stuck up until the change to normal period at the end of a cycle. Resistance units such as 2R are provided to compensate for the resistance of the 2F relays in the A line conductor toward the end of the line, which is removed from this conductor when the lock-out relay is energized. Resistance 3R at the end field station is for the purpose of providing a return path to line B when line N is energized during the conditioning period of a control cycle.

Line impulsing relays P IP and 2P are provided to impulse the A and B line circuit to provide code combinations during the transmission of indications. These relays are conditioned in accordance with the condition of the No. 1 pulse bus and the No. 2 pulse bus as selected by the code jumpers and relay contacts at the different steps of a cycle. Relay P also functions to effect the look-out circuit operation at the beginning of a cycle, in response to a change in condition at the station as repeated and stored by change storing relay CHS It is believed that the nature of the invention, its advantages and characteristic features may be best understood with further description being set forth in the manner of operation.

Detailed operation Normal at-rest condition.Although the system may be initiated from the field stations, the line circuits are normally deenergized and similarly, the remaining circuits of the system are normally deenergized, with a few exceptions. For example, relay WP shown in Fig. 6 is normally energized over a circuit which is controlled by the switch machine and associated apparatus, in a manner which is well-known in the art. The track circuit is preferably of the closed circuit type, so that a normally energized track relay (not shown) is provided to repeat the unoccupied and occupied conditions of the track section. Likewise, one or more normally energized relays control the stick circuit of a normally energized change relay, in such a Way that a change in condition at a field station drops the change relay, which in turn picks up the change storing relay CHS Since these circuit arrangements ISB is actuated, a circuit is closed for picking up relay ISR extending from contact 42 of button I SB, back contact 43 of relay ISRP and Winding of relay ISR, to Relay ISR closes a stick circuit for itself extending from front contact 44 of relay ISR and back contact 2 43 of relay ISRP to the winding of relay ISR.

If button 2SB is actuated, a circuit is closed for picking up relay 2SR extending from contact 45 of button 2SB, back contact 46 of relay ZSRP and winding of relay 28R, to J Relay 2SR closes a stick circuit for itself extending from front contact 41 of relay 2SR and back contact 46 of relay 2SRP to the winding of relay 2SR. If button 383 is actuated, a circuit is closed for picking up relay 3SR which extends from contact 48 of button 383, back contact 49 of relay 3SRP and winding of relay 3SR, to Relay 3SR closes an obvious stick circuit for itself by way of its front contact 55. If button 4SB is actuated, relay 4SR is picked up over a circuit extending from contact 56 of button 4SB and back contact 51 of relay 4SRP to the winding of relay 4SR. Relay 4SR closes an obvious stick circuit for itself by way of its front contact 58.

The picking up of relay ISR closes a circuit for picking up relay I SRP which extends from back contact 59 of relay SAP, front contact 6''! of relay lSR, back contact BI and winding of relay ISRP, to The picking up of relay 28R closes a circuit for picking up relay 2SRP extending from back contact 59 of relay SAP, front contact 62 of relay 2SR, back contact 63 and winding of relay 2SRP, to Stick circuits for relays ISRP and ZSRP are established through their make-before-break front contacts 6i and 63 respectively to at back contact 64 of relay I2CD.

The picking up of relay. 3SR closes a circuit for picking up relay 3SRP which extends from back contact 59 of relay SAP, front contact 65 of relay 3SR, back contact 66 and winding of relay 3SRP, to The picking up of relay 48R closes a circuit for picking up relay 4SRP which extends from back contact 59 of relay SAP, front contact 67 of relay 4SR, back contact 68 and winding of relay 4SRP, to Stick circuits for relays 3SRP and 4SRP are established through their make-before-break front contacts 66 and 68 respectively to at back contact 69 of relay 340D. The picking up of the storing repeating relays ISRP, ZSRP, 3SRP and 4SRP causes the dropping of the associated storing relays by opening back contacts 43, 46, 49 and 57.

The actuation of one or more of the starting buttons during a cycle results in the corresponding storing relay or relays being picked up and stuck up. Then when the system returns to normal, the corresponding storing repeating relay or relays will pick up, stick and cause the release of the associated storing relay or relays.

The stations are arranged in pairs, with each code determining relay controlling the selection of one odd and one even station and the transmission of controls thereto. As a typical example, when relay I2CD is up and both relays ISRP and 2SRP are up during a cycle, odd station (No. 1) and even station (No. 2) are selected and controls transmitted to both stations during the same cycle. With relay IZCD up and relay lSRP up during a cycle, odd station No. 1 alone is selected and controls are transmitted to it alone. Similarly, when relays IZCD and ZSRP are up together during a cycle, station No. 2 alone is selected and the transmission of controls tothis station alone is effected. This discussion applies to relays 340D, 3SR-P and 4SRP which govern the transmission of controls to another pair of stations, No. 3 and No. 4.

The picking up of relay ISRP closes a circuit for picking up relay IZCD which extends from back contact 8| of relay SAP, back contact iii of relay CM, conductor l9, front contact 1" of relay ISRP, back contact 12 and winding of relay lZCD, to When relay 2SRP is picked up alone, then the circuit for picking up relay ltZCD extends from back contact 8| of relay SAP, back contact 10 of relay CM, back contact ll of relay ISRP, front contact 13 of relay ZSRP, back contact 12 and winding of relay IZCD, to If both relays ISRP and ZSRP are up, the circuit previously described through front con tact H of relay ISRP is effective to pick up relay l'lCD. The picking up of relay lZCD closes a stick circuit for itself which extends from winding of relay CM, front contact 14 of relay SRP or front contact 15 of relay 2SRP (or both), front contact 12 and winding of relay IZCD, to

The picking up of relay 3SRP closes a circu for picking up relay 340D which extends from back contacts 8!, 10, H and 13 of relays SAP. CM, ISRP and ZSRP respectively, conductor l8, front contact i6 of relay 3SRP, back contact l! and winding of relay 34CD, to The picking up of relay ASRP closes a similar circuit for picking up relay 34CD, this circuit extendin through back contact 16 of relay SSRP and front contact 18 of relay 4SRP. The picking up f relay SACD closes a stick circuit for itself extend ing from winding of relay CM. one, th' other or both front contacts I9 and of relays SSRP and GSRP respectively and front contact ll of relay 340D to the winding of this relay.

The stick circuits of all code determining relays includes the winding of relay CM, which picks up and removes the potential from conductor 19 so no other CD relay can pick up until th one that is up is deenergized. It is obvious tha in the event of two or more odd or two or more even storing repeating relays being up at the same time with the system in its normal period the corresponding CD relay nearest the p tential at back contact H! of relay CM will ha preference. because the extended pick-up wire I to other CD relays to the right is de-energized.

The picking up of relay IZCD transfers (at its make-before-break contact 64) the stick circuit for relays lSRP and ZSRP to at back contact 8! of relay SAP and at front contact 8-? relay SA. Relays SA and SAP pick up in sequence during the conditioning period at the start of a cycle and are dropped in sequence at the end of a cycle, so that the stick circuit for relays I (with the corresponding CD relay picked up) have been released. Those storing repeating relays (if any) which are stuck up at this time to at a back contact such as 64, 69 or the like of their associated CD relays are not released, so that another CD relay has a chance to be picked up to start another cycle when the previously energized CD relay is deenergized to deenergize and release relay CM by the dropping of the corresponding storing repeating relay or relays.

Briefly stated, as many storing relays may be picked up as there are starting buttons actuated, irrespective of the condition of the system. An exception to'this is that a storing relay such as relay ISR; cannot be picked up when relay ISRP is up, because back contact 43 is open. There is no need of operating relay ISR under this condition, because its associated station is either already being selected or a stored condition for this station is waiting. As many storing repeating relays may be picked up when the system is in its normal period as there'are storing relays up, after which the corresponding storing relays are dropped. Only one code determining relay can be up at the same time and controls will be transmitted to the odd, or even, or both stations associated with this code determining relay, as determined by the picked up condition of the odd, or even, or both storing repeating relays.

It is obvious that after a cycle of operations has been started as a result of the picking up of one storing repeating relay, the other storing repeating relay of the pair must be prevented from picking up. Otherwise, a storing repeating relay picking up after the start of a cycle when its associated CD relay is up, would not be up in time to transmit all of the codes necessary. Therefore, when relay SAP picks up to start a cycle, the removal of potential from conductor 83 at its back contact 59 prevents the picking up of any storing repeating relay. It is understood that under this condition, the storing relay is stuck up until the end of the cycle, at which time the corresponding storing repeating relay can be picked up and stuck up until the end of the next cycle.

It will now be assumed that the operator in the control office desires to transmit controls to station No. 2 illustrated in Figs. 5 and 6. When starting button 2SB is actuated, relays ZSR, 2SRP and I2CD are picked up as above described. A circuit is now closed for picking up relay C which extends from back contact 84 of relay SA, conductor ll, back contact 85 of relay ENC, front contact 86 of relay I2CD and winding of relay C, to Relay C closes a stick circuit for itself by way of its front contact 81 to at back contact 88 of relay SAP, which iseffective until relay SA picks up and thereafter the stick circuit extends to at front contact 84 of relay SA.

The operation of relay C opens the pick-up circuit of relay FC at back contact 89, which prevents the picking up of relay FC after the cycle is initiated by a manual start in the control ofilce. The picking up of relay C closes a circuit for picking up start relay STR which extends from front contact 90 of relay C and winding of relay STR, to A circuit is now closed for picking up relay EPC which extends from front contact 9| of relay ZSRP, front contact 92 of relay lZCD, even control conductor 93, back contacts 94, 95 and 96 of relays 3V, 2V and 'IV respectively, conductor l0, front contact 91 of relay C and winding of relay EPC, to This marks the beginning of the conditioning period by applying potential to line N for the purpose of conditioning the relays at the field stations. Relays IF, IF (and similar line relays at all the stations) are now positioned to the right by means of a circuit extending from the terminal of battery NB, front contact 26 of relay STR, front contact 2| of relay EPC, back contact 22 of relay ENC, conductor I3, Winding of relay IF, back contact 23 of relay EP, N line conductor 24,.winding of relay IF, resistance 3R at the end station, upper winding of relay 2F B line conductor 33, back contact 9 of relay 00, upper winding of relay 2F, through the upper portion of battery AB, back contact 34 of relay ENC, front contact 35 of relay EPO and front contact 36 of relay STR to the terminal of battery NIB. Current flow in this circuit includes the upper portion of battery AB which aids battery NB and is effective to position the 2F relays at all stations to the right and to energize the 2F relay in the control office. A circuit is now closed for picking up relay FP in the control office which extends from polar contact 99 of relay IF in its right hand dotted position and winding of relay FP, to Relay FP closes a circuit for picking up relay SA which extends from front contact I00 of relay FF and winding of relay SA, to A circuit is closed for picking up relay SAP which extends from front contact IUI of relay SA and winding of relay SAP, to

Relay FP (Fig. 5) is picked up over a circuit extending from contact 202 of relay IF in its right hand dotted position and winding of relay FP to A circuit is closed for picking up relay SA which extends from front contact 203 of relay FF and winding of relay 8A to Before the picking up of relay SA relay S0 is picked up over a circuit extending from back contact 294 of relay SA conductor 299 back contacts 205, 206 and 291 of relays 3V 2V and IV in series, control bus contact I91 of relay IF in its right hand dotted position and winding of relay S0 to Relay SO establishes a stick circuit for itself over the circuit just described, to at its front contact 208 which is effective after relay SA picks up.

It is to be understood that relays similar to- IF FP SA and S0 at all other even field stations are operated by means of circuits similar to those just described. At all odd field stations, the SO relays are picked up over a circuit similar to that which extends from applied to conductor 299 (Fig. 6), from back contacts similar to 294 of relays similar to SA and thence through back contacts 29I, 292 and 293 of relays 3V 2V and IV respectively, control bus contact I96 of relay 2F in its right hand dotted position and the winding of the SO relay which is connected to conductor 294.

Referring back to the control oflice, the picking up of relay SAP closes a circuit for picking up relay EP which extends from front contact 29 of relay SAP, back contact 39 of relay E and lower winding of relay EP, to The picking up of relay EP deenergizes line N at back contact 23, to mark the end of the conditioning on period and the beginning of the first off period.

Relay 8A at the end field station is picked up by means of a circuit similar to that described for picking up relay SA and by closing its front contacts 21 and 28, the continuity of the A--B line circuit is established (see Fig. 1). This is effective to energize the A and B lines with potential from battery AB applied to the A line conductor, which maintains the 2F relays (with suitable exponents) positioned to the right.

During this cycle, since it is assumed that a single even station is to be selected, the condition of the A and B line conductors is not changed but these conductors are maintained energized in the same direction so that the 2F relays (with suitable exponents) remain actuated to their right hand positions. Since back contact I02 of relay 2F in the control ofiice is maintained open, the pick-up circuits of relays IM,

2M and 3M are not energized during this cycle. Therefore, (B-) potential is applied to pilot relays IPT and 2PT, over circuits which will be later described, so that these relays are both positioned to the left to select the indication phantom wire.

In the event that starting button 4SB is actuated, relays ISR, 4SRP and 340D are picked up as above described. Since this requires the selection of an even station, the operations are the same for conditioning the line circuits as explained in connection with relay I2CD, except that the circuit for energizing the even control bus 93 which picks up relay EPC now extends through front contact 4SRP and front contact I04 of relay 34CD. Also the pick-up circuit for relay C extends through front contact I05 of relay 340D instead of front contact 86 of relay I2CD. It will thus be seen that the picking up of any CD relay initiates a l control cycle by applying potential to line N during the conditioning period. As will be later explained, the different conditions set up by the different CD relays which are picked up result in distinctive impulses being applied to the line circuits, following the conditioning impulse, as controlled by the jumper and lever connections associated with the one particular CD relay which is picked up during the cycle.

In the event that starting button ISB is actuated, relays I SR, ISRP and I2CD are picked up and the line is conditioned as above described in connection with the operation of button 28B, except that relay EPC is energized by means of a circuit extending from front contact ID! of relay ISRP, front contact I08 of relay I2CD, odd control bus I 96, back contacts I09, III) and III of relays 3V, 2V and IV respectively, conductor I0, front contact 91 of relay C and winding of relay EPC, to

In the event that button 38B is actuated, relays 3SR, BSRP- and 34GB pick up as above explained and the N line circuit is conditioned in the same manner as described in connection with the actuation of button 2SB, except in this case relay EPC is energized over the circuit just described, including odd control bus I96, but this time through front contacts I I2 and I I3 of relays 3SRP and 340D respectively.

Polarity selection of impulses.It will first be assumed (and later described) that the stepping relays in the control office and at the field stations step through the cycle in synchronism (except certain field stations which are dropped out during the cycle). When line N is deenergized to mark the end of the conditioning period as previously discussed, relay IF in the control office, relay I F at the field station illustrated in Fig. 5 and similar line relays at all other field stations are deenergized. The first stepping relay I03 of relay in the control office is now picked up, following which relay E picks up and relay EP drops to mark the end of the first off period.

The picking up of relay IV establishes the No. 1 control conditioning circuit, extending from front contact 9| of relay 2SRP, front contact 92 of relay I2CD, conductor 93, back contacts 54 and 95 of relays 3V and 2V respectively, front contact 95 of relay IV, No. 1 even conductor H6, front contact I I4 of relay I 2CD, jumper 254, EPC bus II5, front contact 98 of relay C and winding of relay EPC, to This circuit is effective to pick up relay EPC during the first o period for energizing line N with potential during the following or first on period.

In the event that jumper 254 is connected to ENC bus II'I instead of EPC bus I I5, then the above described circuit extends by way of bus I I1 and the winding of relay ENC, to which is effective to pick up relay ENC for energizing line N with potential during the first on period.

Relay 2V is picked up during the second "off period and the No. 2 even conductor H8 is selected at front contact 95 of relay 2V. The circui t extends through front contact 9 of relay I2CD and jumper 255' to the ENC bus II I which is effective to energize relay ENC for selecting a potential to be applied to line N during the second on period. In the event that jumper 255 is connected in its alternate position to EPC bus II5, then relay EPC is picked up to select potential for the No. 2 on impulse.

Relay 3V is picked up during the third off period to select the No. 3 even conductor I20 by way of its front contact 94. This circuit is extended through front contact I2I of relay I2CD to lever ZSML. Should lever 2SML be in its right hand position, the conditioning circuit would be connected to the EPC bus H5 for picking up relay EPC to apply potential to line N during the third on period. Or if lever ZSML is in its left hand dotted position, the ENC bus I I I is selected and relay ENC is picked up to apply potential to line N during the third on period.

From the above discussion, it will be apparent that line N is impulsed with a combination (following the conditioning impulse) of impulses with jumpers 254 and 255 and lever ZSML in the positions indicated in the drawings. Also, the polarity tobe applied to line N during an on period is determined by the particular polarity control relay EPC or ENC which is picked up during the preceding off period. In the event that relay 340D is picked up as a result of button 483 being actuated, then the impulses applied to line N are The first impulse (following the conditioning impulse) is as determined by jumper 256 connecting the No. 1 even conductor I I6 by way of front contact I22 of relay 340D to the ENC bus. The second impulse is as selected by jumper 251 connecting the No. 2 even conductor H8 by way of front contact I23 of relay 34CD to the EPC bus. The third impulse is as determined by lever 4SML connecting the EPC bus to the No. 3 evenconductor I20by way of front contact I24 of relay 34CD.

In the event that relay |2CD is picked up as a result of button ISB being actuated, the AB line circuit is impulsed (following the conditioning impulse) with a combination of impulses. The first impulse is because juniper 250 is connected to 00 bus I25 for completing an energizing circuit for relay 0C when relay IV is picked up, which extends from front contact II" of relay ISRP, front contact Hi8 of relay I2CD, odd control conductor I06, back contacts I09 and H0 of relays 3V and 2V respectively, front contact III of relay IV, No. 1 odd conductor I26, front contact I21 of relay I2CD, jumper 250, conductor I25, winding of relay 0C and front contact II of relay C, to Relay 00 connects potential from battery AB through the lower winding of relay 2F and front contact 9 of relay O0 to B line conductor 83, while potential from battery AB through the upper winding of relay 2F is connected to the A line conductor M at front contact I4 of relay 0C.

The second impulse is because jumper 25I- is effective to deenergize relay 00 when the No. 2 odd conductor I28 is selected at front contact HII of relay 2V, which conductor extends through front contact I29 of relay I2CD to jumper 251. Relay 00 remaining deenergized reverses the connection of battery AB to lines A and B from that explained in connection with the first impulse. The third impulse is because with lever ISML in the position shown, relay 0C is deenergized when the circuit including the No. 3 odd conductor I and front contact I3I of relay I2CD is established.

Jumpers 252, 253 and lever 3SML are selected by relays 3SRP and 34GB and when connected as shown, result in relay 00 being picked up during the No. 1 and the No. 2 odd steps respectively, to make the first two impulses in the A line This is because these two jumpers are connected by way of front contacts I32 and I33 of relay 340D and the No. 1 odd and No. 2 odd conductors to the odd control conductor I06 by way of front contacts III of relay IV and III) of relay 2V respectively, at the first two steps of the cycle. Odd control conductor I06 extends through front contact I I3 of relay 340D and front contact N2 of relay 3SRP, to Lever 3SML de-energizes the 00 bus I25, as selected on the third step by way of front contact I34 of relay 340D.

From the above description it will be seen that line circuits N and AB are distinctively conditinned with and impulses, as selected by a combination of SRP and CD relays. In other words, a CD relay being picked up in combination with an even numbered SRP relay, causes line N to be impulsed with a combination of and impulses as determined by the associated jumper and lever connections. A CD relay being up in combination with an odd numbered SRP relay causes the A and B line circuit to'be impulsed with a combination of and impulses as determined by the associated jumper and lever connections. Since these two line circuits are independently energized without interference between the two circuits, it is apparent that the system will function to transmit a single combination of impulses for selecting a single odd or even station, or a double combination of impulses for selecting an odd and an even station during the same cycle.

Line impulsing and operation of stepping relay ban7c.-Relay IV in the control ofiice is picked up during the first off period as a result of relay IF being de-energized to drop relay FP. The circuit for picking up relay IV extends from front contact I 35 of relay SA, back contact I36 of relay FP, back contact I31 of relay VP, back contact I-3B of relay 2V and winding of' relay IV, to

(). Relay IV closes a stick circuit for itself extending from front contact I of relay SA, front contact I39 and winding of relay IV, to Relay E is now picked up over a circuit extending from back contact I40 of relay 3V, back contact I4I of relay 2V, front contact I42 of relay IV, back contact I43 of relay VP and winding of relay E, to

Relay EP is now dropped due to the energizing circuit through its lower winding being open at back contact 30 of relay E. Relay EP is slightly slow to release due to its upper winding being short circuited at its front contact I44. This slow releasing feature of relay EP is for the purpose of timing the off periods between impulses. The slight delay in the release of relay EP delays the energization of the line. The release of relay EP and the resulting energization of line N at back contact 23 marks the end of the first off period and the beginning of the first on period.

Relays IF and FF now pick up in turn and relay FP closes a circuit for picking up relay VP extending from front contact I 45 of relay SA, front contact I46 of relay F'P, back contacts I41 and I 48 of relays 3V and 2V respectively, front contact I49 of relay IV and winding of relay VP, to Relay VP establishes a stick circuit for itself extending from front contact I45 of relay SA, front contact I60 of relay VP and over the remainder of the previously described circuit to the winding of relay VP. The stick circuit is effective until stepping relay 2V picks up and opens its back contact I48, which occurs during the second off period. For maintaining relay VP in its energized condition during the second off period, an additional stick circuit is established which extends from front contact I45 of relay SA, back contact I46 of relay FP, front contact I6I and winding of relay VP, to

Relay VP, in picking, up opens the circuit of relay E at back contact I43, so that relay E drops after a predetermined time interval and closes the pick-up circuit for relay EP at its back contact 30. Relay EP picks up and deenergizes line N by opening its back contact 23 to mark the end of the first on period and the beginning of the second off period.

Relays IF and FF are now dropped and relay 2V is picked up over a circuit extending from front contact I35 of relay SA, back contact I36 of relay FP, front contact I3! of relay VP, back contact I62 of relay 3V, front contact I63 of relay IV and winding of relay 2V, to Relay 2V establishes an obvious stick circuit for itself by way of its front contact I64.

Relay E is now picked up over the previously described circuit through back contact I40 of relay 3V, which now extends through front contacts MI and I43 of relays: 2V and VP respectively. Relay EP is dropped and line N is energized as before, which marks the end of the second off period and the beginning of the second on period.

Relays IF and PP are now picked up in turn and relay VP is dropped, because one stick circuit is open at back contact I48 of relay 2V and the other stick circuit is open at back contact I46 of relay FP. Relay E is now dropped because its energizing circuit is open at front contact I43 of relay VP. Relay EP is again energized and line N is deenergized to mark the end of the second on period and the beginning of the third off period.

Relays IF and FF are now dropped and relay 3V is picked up over the previously described circuit, which now extends through back contact I31 of relay VP and front contact I38 of relay 2V to the Winding of relay 3V. Relay 3V closes an obvious stick circuit for itself by way of its front contact I65. Relay E is now picked up over a circuit extending from front contact I40 of relay 3V, back contact I43 of relay VP and winding of relay E, to Relay EP is now dropped to mark the end of the third off period and the beginning of the third "on period, by energizing line N.

Relays IF and FP now pick up in turn and relay VP is picked up over the previously described circuit which now extends through front contact I41 of relay 3V. Relay VP closes the previously described stick circuits for itself through its front contacts I60 and I6I. Relay E is now released because the potential applied to its winding through front contact I 40 of relay 3V is interrupted at back contact I43 of relay VP. Relay EP is picked up as before and line N is deenergized to mark the end of the third on period and the beginning of the change to normal period.

Relays IF and PP now drop in turn and since there is no other stepping relay to be picked up, relay VP remains stuck up and relay E cannot again pick up to deenergize relay EP. After a predetermined interval of time, relay SA is dropped because its energizing circuit remains open at front contact I00 of relay FP. Relay SAP is dropped after an additional interval of time because its energizing circuit remains open at front contact IOI of relay SA. The dropping of relay SA deenergizes the pick-up and stick circuits of the stepping relays and the half step relay, by opening its front contacts I35 and I45, with the result that these relays are dropped.

Relay 2SRP is dropped when relay SA drops its front contact 82. The energizing circuit of relay I 2CD is opened at front contact "I5 of relay 2SRP, with the result that relays IZCD and CM are dropped. Relay C is deenergized when relay SA drops its front contact 84 and since relay I2CD is dropped at substantially the same time, the pick-up circuit of relay C through front contact 86 of relay IZCD is interrupted. Relay STR is deenergized when relay C drops its front contact 90. Relay EP is deenergized when relay SAP drops its front contact 29.

Since relays IF and FP operate substantially in synchronism with the corresponding relays in the control oflice and since the stepping relays illustrated in Figs. 5 and 6 operate substantially in synchronism with the stepping relays in the control office, it is not believed necessary to explain the field station stepping operations in detail. It should be mentioned, however, that the SA relays at the field stations are dropped substantially in synchronism with the corresponding relay in the control oflice and when relay 8A at the end station is released, the AB line circuit is deenergized which results in deenergizing relay 2F in the control ofiice and the 2F relays at the field stations. The system is now in its normal condition.

Station selection and transmission of controZs.It will now be assumed that the stepping relays in the control oiiice and at the field station operate as above described and an explanation will be given of the circuits which are efiective during this operation for selecting the illustrated even station and the transmission of controls thereto.

As above explained, line N is conditioned with ill;

a impulse for picking up the station relays similar to relay S at all field stations. During each off period of the cycle, all SO relays which remain up throughout the preceding on period are stuck up by means of a circuit similar to that extending from front contact 208 of relay S0 front contact 204 of relay SA back contact 2I2 of relay FF (and contact I91 of relay IF in its neutral position in multiple) and winding of relay S0 to With jumpers 2I0 and 2 connected as shown in Fig. 5, the No. 2 even station is selected when starting button 2SB in the ofiice is actuated. It will be recalled that the actuation of this button causes relays 28R? and I2CD to be up during the cycle and that these two relays up together energize even control bus 93. This energized bus is extended to relays EPC and ENC in sequence on the first two steps, by way of jumpers 254 and 255 so that line N is impulsed for station selection.

Relay IF at the illustrated station (and similar relays at all other stations) is positioned to the right by the impulse. A circuit is closed for energizing relay SO which extends from front contact 208 of relay S0 back contacts 205 and 206 of relays 3V and 2V respectively, front contact 207 of relay IV jumper 2l0, control bus contact I91 of relay IF in its right hand dotted position, terminal I and winding of relay SO to At those stations having a jumper similar to 2 I 0 connected to the control bus, relays similar to so will be maintained energized during the first on period by means of a circuit similar to that just described. At those stations not having a code jumper similar to M0 connected to the control bus, the SO relays will be dropped because there is no circuit for maintaining them energized.

When the system advances into the second off period, relay SO and similar relays at other stations, which are up will be stuck up as previously described. It is obvious that the stick circuits of those station relays similar to relay SO which were dropped during the first "on period, are not completed during the second off period since their contacts similar to 208 are open.

The system advances into the second on period after relay 2V has been picked up and the impulse applied to line N is effective to position relay IF (and similar relays at all other stations) to the left. A circuit is completed for energizing relay SO extending from front contact 208 of relay S0 back contact 205 of relay 3V front contact 205 of relay 2V jumper 2H, control bus contact I91 of relay IF in its left hand dotted position, terminal I10 and winding of relay S0, to Any other station with a jumper connection similar to 2| I and with its SO relay up, will maintain this relay energized throughout the second on period in a similar manner. Any other station with its SO relay up and without such a jumper connection will drop this relay in the second on period.

During the third off period, relay 3V is picked up and relay S0 is stuck up over a circuit extending from front contact 208 of relay S0 front contact 205 of relay 3V and winding of relay S0 to This maintains relay SO picked up during the remainder of the cycle, ir-

respective of the number of stepping relays which may be used for the selection of controls after the station is selected. With relay SO picked up after station selection, additional impulses are effective to operate only those stepping relays at this particular station, since the circuit for the stepping relays is by way of front contact 2I3 of relay S0 It will be understood that the contacts similar to H3 of other station relays which are dropped during the cycle, are effective to discontinue the stepping relay operation at those stations.

During the third on period, the No. 3 control impulse is as determined by lever 2SML of Fig. 4A being actuated to its right hand position. This impulse in line N actuates relay IF to the right and closes a circuit for energizing relay SMR. which extends from front contact 208 of relay S0 front contact 205 of relay 3V contact I91 of relay IF in its right hand dotted position, control bus conductor I9l, front contact 2 I4 of relay 3V and upper winding of relay SMR to This actuates relay SMR to the right, which closes a circuit for energizing the motor to operate the track switch TS to its normal locked position.

It will be obvious that lever ZSML'in its alternate position is effective to energize relay ENC, which applies a impulse to line N at the third step for actuating relay IF to the left. This transfers the above described circuit from at contact I91 of relay IF to the control bus and thence through conductor I90 and front contact 2H5 of relay 3V to the lower winding oi relay SMR This circuit is effective to energize relay SMR, in the opposite sense for actuating the switch machine motor in the proper direction to operate the track switch TS to a reverse locked position. In a similar manner, any num' ber of additional steps may be provided for trans mitting additional controls to the selected field station for governing the signals and such other devices as may be necessary.

It will be understood thatcontacts 2 I4 and 2 I5 on relay 3V are typical of the arrangement used when additional steps are provided. For example, wires I90 and I9I will be connected through back contacts of additional stepping relays starting at the last stepping relay of the series and extending up to contacts such as 2M and M5.

During the selection of an even station alone, odd control relay 00 of Fig. 3A remains deenergized, due to the No. 1 and No. 2 odd. control conductors which extend through jumpers 250, 25L 252 and 253 to relay OC not being energized. This is because odd control bus I06 isdeenergized at front contact I01 of relay ISRP which is down. This results in line A being energized continuously from the terminal of battery AB so that relays similar to relay 2F at all odd stations remain actuated to their right hand positions. A series of all impulses applied to line A during the station selecting steps of a cycle corresponds to a phantom code and does not result in the selection of an odd numbered station.

Assuming that starting button ISB alone is actuated toinitiate a cycle of operations, then relays ISRP and I2CD will be up during the cycle and odd. control bus I06 will be energized. This results in the selection of the N0. 1 odd conductor I26, the No. 2 odd conductor I28 and the No. 3 odd conductor I30 on the three steps of the cycle respectively. Since conductor I26 extends through front contact I21 of relay IZCD and jumper 250 to odd control bus 'I25,'the firstimpulse applied to line A (with line B serving as.

the return conductor) is because relay 0C is picked up.

With conductor I28 extending through front contact I29 of relay I'ZCD to jumper 25!, which is disconnected from the 0C bus, relay 0C is deenergized on the second step so that line A is energized with a impulse from battery AB. Since conductor I30 extends through front contact I3! of relay I2CD to lever ISML and since this lever is shown disconnected from bus I25, relay 00 remains deenergized so that the third impulse applied to line A is Referring to the field station circuits, relay ZF is actuated to the left by the first impulse and a circuit is closed for energizing the station relay (S0 with suitable exponent) at odd station No. 1. This circuit is similar to that previously traced in connection with even station No. 2, except that it extends from a terminal such as H6 at the odd station through conductor 294, contact I96 of relay 2F in its left hand dotted position, control bus jumper 2 I6, front contact 293 of relay IV back contact 292 of relay 2V back contact 29! of relay 3V conductor 290 (which corresponds to conductor 29!) associated with even station No. 2) and through a front contact similar to 208 of the station relay to The second impulse which is actuates relay 2F to the right and completes the above described circuit by way of contact I96 in its right hand dotted position, control bus jumper 2", front contact 292 of relay 2V back contact 29! of relay 3V conductor 290 and over the remainder of the previously described circuit.

The third impulse which is actuates relay 2F to the right and extends which is applied to conductor 290 from the front contact similar to 208 of the station relay, through front contact 29! of relay 3V contact I96 of relay 2F in its right hand dotted position, control bus front contact 295 of relay 3V and upper Winding of relay SMR to This actuates relay SMR, to the right for actuating the switch machine at the odd station to its normal locked position, in a manner which is obvious from the previous description.

It has been mentioned that the 2F relays are not dropped during a cycle for the selection of an even station. During a cycle for the selection of an odd station, the 2F relays at the stations are of course shifted during off periods, in accordance with the polarities required for the succeeding on periods. Relay 2F in the control oflice is not dropped during stepping because the make-before-break contacts 9 and I4 of relay 0C prevent the deenergization of relay 2F. This results in back contact I02 of relay 2F remaining open during a control cycle to prevent the energization of any message relay IM, 2M or SM of Fig. 4B.

During the selection of the No. 1 odd station and the transmission of controls thereto, line N is impulsed with a series of impulses which corresponds to an even phantom code and is ineffective to select any even station. This series of impulses is provided by relay ENC being picked up during all station selecting impulses over a circuit extending from back contact 9! of relay ZSRP, front contact I55 of relay I 2CD, even phantom bus I56, front contact I51 of relay IV, conductor II'! and winding of relay ENC, to The even phantom bus is also energized for the same purpose when relays 3SRP and 34GB are up, through back contact I93 of relay 4SRP and front contact I68 of relay 340D.

It will be obvious that odd station selection may be accomplished with additional steps provided in the manner previously mentioned in connection with even station selection and that additional steps may be provided for the transmission of additional controls for governing signals and such other devices as may be necessary.

The jumpers connected as shown in Fig. 4A

indicate the method of odd and even station selection on two steps each. This invention contemplates the use of a different number of steps during a cycle for selecting odd and even stations. For example, the No. 1 odd conductor I26 might be selectively connected by jumper 250 or 252 to bus 00 for selecting station 1 or 3 respectively on the first step. The No. 2 odd conductor I28 could then be connected through switch machine lever or signal lever contacts to selectively energize bus 00 on the second step. Then with both the No. 1 even and the No. 2 even conductors H6 and H8 connected by means of jumpers 254, 255, 256 and 25! as shown, even station selection is accomplished on two steps, after which the No. 3 even wire I20 connected through switch machine or signal lever contacts, selectively energizes buses EPC and ENC on the third step. In other words, while jumpers 250 to 251 inclusive are shown for selecting both odd and even stations on two steps, these jumpers may be replaced by jumper and lever contacts in any desired combination.

Diplezz: transmission.It has been explained how the present invention functions during the transmission of controls to even stations and to odd stations on separate cycles of operation. Diplex transmission is effected when both storing repeating relays and the associated CD relay are up at the same time when a cycle is initiated.

For example, relays ZSRP, ISRP and I2CD may be up at the start of a cycle. In this event, station No. 2 is selected over the N line circuit and station No. 1 is selected over the AB line circuit in the manner already explained.

Since the N line circuit is used for controlling the stepping at all stations and for the selective conditioning of a polar relay during stepping at each even station and since the AB line circuit is independently used for the selective conditioning of a polar relay during stepping at each odd station, both stations of a pair are simultaneously selectable and controls may be transmitted to both during the same cycle. An explanation oi the effect of simultaneously conditioning the two line circuits has been given in connection with the fundamental line circuit arrangement shown in Fig. 1.

Automatic start by a field station.Whenever the system is in the normal period or period of blank, it may be initiated from a field station, either in response to some automatic change in trafl'ic conditions or in response to the operation of a traii'ic controlling device to a new position, such as moving the track switch TS from its reverse locked to its normal locked position during a control cycle. Such a change results in change storing relay CHS being picked up. It is not believed necessary to show or describe the detailed circuits for picking up relay CHS since this may be accomplished in the manner disclosed in connection with relay OHS shown and described in the patent to DeLong et al., Patent No. 1,852,402 issued April 5, 1932.

The picking up of relay OHS closes a circuit for picking up relay P extending from back contact 2I8 of relay SA back'contact' 219 of relay FP front contact 220 of relay CHS and upper winding of relay P to Relay P closes a stick circuit for itself extending from back contact 218 of relay SA front contact 22l and upper winding of relayP to The actuation of the P relay contacts opens the A line conductor, extending from the calling station toward the end of the line, at back contact 40. The A line conductor is connected to the N line conductor at front contact 40of relay P in series with resistance 2R the upper winding of relay L and back contact 222 of relay SA.

Since line N is open at front contact 2| of relay EPC in the control office, there is no potential applied to this line up to the calling station. A circuit is effective for energizing the AB line circuit, which extends from the terminal of battery AB, lower Winding of relay 2F, back contact 14 of relay 0C, A line conductor 4!, lower winding of relay 2E front contact 40' of relay P resistance 2R upper w nding of relay L0 back contact 222 of relay SA line N through to the end station, resistance 3R B line conductor, upper winding of relay 2E B line conductor 33, back contact 9 of relay 0C and upper winding of relay 2F to the terminal of battery AB.

Current flow in this circuit results in picking up relay 2F in the control office and actuating relay 2F at the field station to the right. It will be understood that all 2F relays at both odd and even stations, are actuated to the right. Helay LO at the calling station is picked up. Since the N line conductor is connected to the B line conductor at the end station, those IF relays farther out theline pick up and effect the picking up of the SA relays at the respective stations.

The picking up of relay 2F in the control office closes a circuit for picking up relay FC which extends from back contact 29 of relay SAP, conductor 278, front contact 8' of relay 2F, back contact 89 of relay C, back contact l of relay STR and winding of relay FC, to Relay FC closes a stick circuit for itself through its front contact IE to at back contact 88 of relay SAP until relay SA is picked up and thereafter to at front contact 84' of relay SA.

A circuit is now closed for picking up relay STR which extends from front contact 1 of relay FC and winding of relay STR, to

A circuit is also closed for picking up relay ENC which extends from back contact I 66 of relay C, front contact I61 of relay FC and winding of relay ENC, to The picking up of relays ENC and STE applies potential to line N for energizing all other IF relays connected in this line, including relay l-F Relay SA is picked up to open the circuit including resistance 2R Other SA relays likewise pick up.

Relay IE (not shown) at the end field station is effective when actuated to pick up relay FP (not shown), which in turn picks up relay SA by means of circuits which will be obvious from those shown. in connection with the No. 2 station. This establishes the line circuit arrangement as illustrated in Fig. 1 (assuming front contacts 27 and 28 of relay SA picked up). The continuity of the A line conductor at the calling station is established at polar contact 2250f relay IF so that this line conductor is pieced out irrespective of its open condition at back contact 49 of relay P The station relays (S0 with suitable exponent) are picked up at all odd stationsby means of a circuit, similar to that extending through contact I96 of relay 2E in its right hand dotted position. The station relays at even stations are picked up over circuits similar tothat previously ing each on period from the terminal.

of battery AB because relay 00 remains deenergized throughout the cycle. Therefore, the IF relays at the stations are actuated to the left in response to a series of impulses and the ZF-relays areactuated to the right in response to a series of impulses applied to line A. It will be recalled that a series of all impulses, positioning the 2F relays to the right, corresponds to a phantom code and does not select any odd station and that a series ofall impulses, which position the. IF relays to the left, also corresponds to a phantom code combination and does not effect the selection of an even station.

7 After relay- SA is picked up at the calling station, a circuit is-closed forsticking the lockout relay which extends from front contact 221 of relay SA front contact 228and lower winding of relay L0 to The picking up of relay IF in. the control office, due to the energization of line N, is followed by the pick-- ing up. of relays FP, SA, SAP and EP inv the manner previously described in connection. with.

a control cycle. The system is now stepped through the cycle as previously described and.

during the off periods between the energized periods. of theline circuit, the A and B line conductors are conditioned for transmitting indication code combinations.

Registration of a field station.--It. will now be assumed that the system is advanced through a cycle and an explanation-will be given of the.

manner the. field station (illustrated in Figs. 5 and 6) is registered in the control office The AB. line circuit is impulsed during the first off. period (following the conditioningperiod above explained) once or" twice or not at all, as determined by the connections of jumpers.

28B and 281. With jumper 280 connected to. the

No. 1 pulse bus 299 as shown: and with jumper 28! disconnected as shown, the AB' line circuit is impulsed once. It will be recalled that relay P was picked up to start the cycle. It is stuck up until relay SA picks up, when its energizing circuit is opened at back contact 2|8' of relay SA P is. established when relay SA picks upwhich extends from front contact 282 of relay FP front' contact 283 of relay SA front contact 284 of relay'LO back contacts 285, 286" and 281 of relays VP 3V and 1V respectively, the No. 1 conductor, jumper 280,. No. 1 pulse bus 299 and upper winding of relay P to.

With relay P picked. up and its back contact 49. open, the AB line circuit is deenergized'when. relay [F is dropped. at the start of the first.

foff? period, by the opening of its contact.225.

Another energizing circuit for relay

Images