US2097789A - Centralized traffic controlling system for railroads - Google Patents

Description

w, D. HAlLEs 2,097,789

CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Npv. 2, 1937.

6 Sheets-Sheet lV Filed July 30, 1935 Iv N: J H R am Tm mw A A... r m ,jm flwlwl v Vf 3 1 To Aromm* ..lllJrl E, @F. P IWW lllww @n lvT s# Nk H +V E im om S ma E I .1+ I ..Al+ l rl.m www l. mm mm Law HARM 3 T omv k| 3 uz d@ I W. D. HAILES Nov. 2, 1937.

CENTRALIZ'ED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Filed July 50, 1955 6 Sheets-Sheet 2 MNZTMZ@ BY w ATTQRN EY W. D. HAILES Nov. 2, 1937.

VCENTRALIZED TRAFFIC CONTROLLING SYSTEM FQR RAILOADS 6 Sheets-Sheet 5 Filed July 30, 1935 Nov. 2, 1937. W. D. HAILES CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS 6 Sheets-Sheet 4 Filed July 50, 1935 JE M Mum @ ATTORNEY 6 Sheets-Sheet 5 ATTORN EY W. D. HAlLES CENTEALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Filed July 50, 1935 No'v. z, 1937.

Nov. 2, 1937.

w. D. HAILES Filed July 50, 1935 S EN Patented Nov. 2, 1937 UNITED STATES PATENT OFFICE wiiiiam D. Hanes, Brighmmiv. Y.,y assignor to General Railway` Signal` Company, Rochester,

Y Application July 30, 1935, Serial No. 33,8261

iol claims. (ci. 1ra-.iriaA This invention relates.V to centralized traffic controlling system; for railroads, and*` it more particularly. pertains to the communication part of such system.

By means of `thecentralized traffic controlling system. contemplated by the present invention a central control olce is placed in communication with a number of outlying iieldstations in such a waythat: controls may be transmitted to these field stations for governing the operation of traflic controlling devices located at the various stations. Likewise the conditions of the various traffic controlling devices at eachstation are transmitted from the station to the-control office to advise the voperator of the location of trains and the condition of the traffic controlling devices, such conditions being transmitted as indications. Y

` `The present invention more particularly relates to a centralized traffic controlling system wherein the supervision of the trafc governing devices andthe indication of their conditions are accomplished over a communication system comprising two line circuits, namely a control line circuit and an indication line circuit. The present invention is more particularly directed to a traffic controlling system in which the distance between certain of the field stations and the control oflce is such that it is impractical to transmit impulses between the control oflice and these certain field stations without the use of undesirably high line voltages or unduly large line conductors,` because of the length of the line circuits. f

An important feature of the present invention is a storage and repeater arrangementwhereby it is'possible to operate one or more laterals or branches extending from the main line of the communication system, without the necessity of looping the line circuit of such laterals in series with the main line circuit, with the consequent need of high line voltage and/or large line conductors. It will be obvious from the description which follows that a storage and repeater arrangement as disclosed'in the present invention may be installed at the locations where such laterals branch off from the main line, thus repeating controls and/or indications from the main line to these branches `with a consequent reduction in line voltage and/or line conductor values required. It `will also be obvious that sub laterals may be branched oir the above mentioned laterals by means of the storage and repeater arrangement disclosed, all 'within' the 'scope of the present invention.

' Another'objectof the present invention is theY provision of arepeating circuit arrangement so that distant field stations may operate inconnection with the i,communication vsystem without the need of increasing-the size of the line conductors or providingv line voltages beyond a reasonable value. As a result of the repeating arrangement provided in the present invention, installation costscf a centralized traffic controlling system are reduced because it is possible to keep the'size of the line battery and the line conductors down to a.- mim'mum. In other words the present circuit arrangement yis so arranged that when the economical'limit of line wire size is reached and the `economical limit of line battery size is reached, 'the line circuit will be arranged to repeat into another'line circuit and this process can be repeated as often as required. This applies to the 'controlline circuit and the indication line circuit.

Another object ofthe presentr invention is the provision of a circuit arrangement for directly repeating impulses from a primary control line circuit which extends from the control oflice to a repeater location, into a secondary control line circuit whichv extends from the repeater station to one or more distant field stations.

Another object of the present invention is the provision of astorage arrangement at the repeater location, whereby indications transmitted from a distant eld station during one cycle of operation of the communication system are received and stored at theA repeater' location and then retransmitted from the repeater location to the control oflice during a succeeding cycle of operations of the communication system.

Still another-objectofthe present invention is the provision of means for precharging the indication line circuitlextending from the control oiiice to the repeater location in advance of the transmission of Veach indication to the control office and for'precharging the indication line circuit which extends from the repeater location to the distant field stations in advance of the transmission of each indication to the repeater station.

The advantages of Vsuch a precharging arrangement will be briefly pointed out during the following description, while a more detailed discussion of such an arrangement is set forth in applicants prior Patent No. 2,045,908, granted June 30, 1936.

Other objects, purposes and characteristic features of the present invention will be in part obvious from the accompanying drawings and in ment at the control oice end of the communication system.

Figs. 2A, 2B and 2Cv illustrate in a diagrammatic and conventional manner'the circuit' organization at the repeater location.

Fig. 3V illustrates in a diagrammatic and conventional manner the application of the present invention to a eld station operating in connection with the communication system.

In following the circuits of the present drawings Fig. 1B should be placed below Fig. 1A, Fig. 2A shouldbe placed to-the right of Fig. 1A, Fig. 3 should be placed to the right of Fig. 2A, Fig. 2B should be placed belowFig. 2A and Fig. 2C should be placed below Fig. 2B, with c orrespondingly identied lines in alignment.

, For-the purpose of simplifying the illustrations and facilitating in the explanation the various parts and circuits constituting the embodiment of the invention have been shown diagrammatically and certain conventional illustrations have been employed, the drawings having been made more with the purpose of making it easier to understand the processes and mode of operation thanwith the idea of illustrating the specic 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 connectionsv to the terminals ofY batteries or other sources of electric current instead of showing all'of the wiring connections to these terminals. i l l The symbols and are employed to indicate the positive and negative terminals respectively of suitable batteries or other sources of current Yand the-circuits with which these symbols are used always have current flowing i-n the same direction, that is from Ato The symbols (B+) and (B are employed to indicate the positiverand negative-terminals respectively of a battery or other source of direct current having a mid-tap (CN) and the circuits with which these symbols are used Vmay have current Viowing in one direction or another depending upon whether the circuitis connected to (B+) or (B ,Y A

Insome of the drawings, Figs. 2A, 2B and 2C for examplefcertain relays have been shownrin full lines onrone drawing and inp-,dottedlines on an adjacent drawing. vThe relays shown in dotted lines have been given the samereference characters as applied to these relays shownk in full lines since they are the same relays` as indicated by the dotted line connections from one drawing to another. It is thus believed unnecessary to show the windings of the relays-illus- Y trated in dotted lines since the windings of these relays are indicated in the gures which show therrelays by full lines. Y

Control oce equipment-The control oiice equipment includes a neutral line relay F'which repeats the impulses applied to the control line circuit, comprising control line conductorv CL and control return conductor CR, by means of battery -CB, l\Teutral line repeating relay FP Yre- 'Bushnell Ser. No. 640,062 iled Oct.

peats the impulsesrapplied to relay F and since relay FP is of the quick acting type it follows the operations of relay F with small delay. Neutral line repeating relay ZFP repeats the operations of relay FP. Slow acting relay SA is used for defining the bounds of each operating cycle, this relay being picked up* at the beginning of each cycle,'remains up throughout the impulses during .the cycle Vand is dropped atthe end of the cycle.

Cycle determining relay C and code determining relay CD are picked up at the beginning of ya cycle, during which controls are transmitted, Y by means of starting button SB. The detailed circuits for controlling the operation of relays C and CD are not shown since they are immaterial for an understanding of the present invention and may be arranged as shown in detail in the prior application of T. J. Judge and C. S. 28, 1932, corresponding to British Patent No. 419,399.

f Field cycle determining relay FC remains down during a control cycle but is picked up during a duplex cycle or a cycle for the transmission of indications alone. The circuit arrangement of relay FC is likewise omitted from the present drawing for the sake of simplicity and this relay may have its circuit controlled in the same manner as disclosed in the above mentioned application Ser. No. 640,062.

Code sending relays PC and NC are for the purpose of providing (-1-) and impulses respectively in the control line circuit during a cycle of operations. Relays MB and MF are for the purpose of receiving indications over the primary indication line circuit, comprising indication line conductor IL and indication return conductor IR, during an operating cycle. The executing circuit arrangement of relays MB and MF is not shown since this arrangement is immaterial for an understanding of the operation of the present embodiment and may be exactly the same as disclosed in the above mentioned prior application No. 640,062. This executing circuit arrangement is controlled by the lower contacts on relays MB, MF, FP andFC as shown in Fig. 1B, with the indication storing relays being omitted. It will be understood that the indication storing relays are selectively energized with or current as determined by the positions of relays MB and with these relays selected by the stepping relay bank as fully disclosed in the above mentioned application Ser. No. 640,062.

A suitable step-by-step relay bank is employed including relays VP, lV, 2V and.' LV. Relays lV, 2V and LV take their steps during the cie-energized or oi periods of the controlline circuit and relay VP shifts its position during the energized or on periods of the control line circuit.A When the stepping relays are picked up they are stuck up until the end of the cycle. Half-step relay VP is picked up and dropped during alternate on'periods of the cycle, all-of which will be pointed out in detail. Control line impulsing relay E controls the application of impulses to the control line circuit by openingand closing the energizing circuit of the PC and NC relays at the proper times as determined by the response of the stepping relay bank in the control oice to the impulses and the time spaces.

Resistance lCRS is acharging resistance for charging the indication line circuit extending from the cnice to the repeater station to apply a flow of charging current at the beginning of Although not shown in the present drawings it will be understood that the control ocelis provided with. a suitable control machine which includes a miniature track diagram representa` tive of the actual track layout in the eld. Cer` tain control levers and buttons which are manually operable to obtain the desired control are included in the control machine, switch machine lever` SML and starting button SB being typical of such devices. It Will be understood thata starting button is provided for each `group of control levers and is associated'with a particular eld station so that the positioning of the con-v trol levers for a particular station results inthe transmission of controls to that station follow# ing the operation of the associated starting button. Station selection is provided by the particular CD relay which isv picked up in response to the operation of a particular starting button, by connecting the PC and NC relays to the channel circuits selected by the stepping relay bank by means or code jumpers connected in various combinations for providing a station selecting code.

Repeater station equipment- Referring to Figs. 2A, 2B and 2C the repeater station includes a biased to neutral polar kline relay F1 which repeats the polar impulses applied to the primary control line circuit in the control oiice. The and impulses applied to the primary control line circuit and received by relay F1 eitiect the operation of relays `FC1 and N01, respectively, to apply corresponding polar impulses to the secondary control line circuit, comprising controlline conductor CL1 and control return conductor CR1 extending to the field station or stations beyond the repeater station. These iinpulses in line CL1 are repeated (irrespective of their polarity) by neutral relay FN1. c

A stepping relay bank comprising relays VP1, IV1 2V1 and LV1 are operated by the impulses applied to the control line circuit in the oice. This stepping relay bank operates substantially in synchronism with the stepping relay bank in the control office, with the exception that relay LV1', which responds to the de-energization` of control line circuit CL1 following they last impulse, is not released like the corresponding relay Vin the control office but remains stuck up jand functions as a stored starting relay for initiating a second cycle of operations, following ,the receipt of a rst seresof indications transmitted from a .distant iieldstation and received in the repeater station. f

`Relay E11 responds tothe operation of the `stepl ping relay bank and is for the purpose of pro- Viding stick circuits for relays MB1 and MF1 as will be later pointed out.Y Relays MB1 and MF1 are message receiving relays which correspond "to relays MB and MF respectively in the control oilice. Relays MB1 and MF1 receive the indications which are transmitted from a distant field station and cause these indications to be stored by storing relays STO1, S1102, STO3 and STO4 during a particular cycle of operations. These storing relays are energized vin various combinations in accordance with the indications received from a distant field station during a particular cycle and are stuck up until the next succeeding cycle, when these indications are transmitted to the control office in accordance with the ombinations of storing relays which were energized during the previous cycle.

Relays FP1, 2FP1 and SA1 correspond to relays FP, 2FP and SA respectively in the control oice, that is relays FP1 and 2EP1 are picked up and dropped in sequence in response to the impulses applied to control line CL. Relay SA1 is picked up at the beginning of each cycle, remains up throughout the cycle and is dropped at the end of the cycle. K Relay SB1 is a repeater of relay SA1.

Relays PB1 and PF1 are for the purpose of applying indication impulses to the indication line circut extending from the repeater station to the control oilice during a cycle in accordance with the indications which were stored at the repeating station during a preceding cycle as manifested by the particular combination of storing relays picked up.

Relay FC1 corresponds to relay FC in the control oflice in that it is picked up in response to the initiation of a cycle from a eld station and remains stuck up until the end of the cycle. Lock out relay L01 is provided for the purpose of initiating the system in the control oice in response to a eld start condition at a distant iield station and in response to a stored Start condition at the repeater station. Relay L01 is picked up to initiate an indication cycle and is dropped when such a cycle is initiated from a distant eld station. During the consequent cycle the indications are transmitted from the distant field station and stored in the repeater station and at the end `of this cycle, relay L01 is again picked up to initiate the system `through a second cycle of operations and to lock out all distant eld stations to prevent any distant eld station transmitting indications during this second cycle of operations.

Resistance CRS1 is a charging resistance for charging the indication line circuit extending from the repeater station to the distant stations to apply a flow of charging y ning'of each period of an indication cycle which follows a period during which the indication line circuit including conductor IL1 has been conductively closed or opened at the field station. Resistance IR1 is a compensating resistance for compensating for the lower winding of relay L01 which is removed from the indication line circuit afterthe lock-out period of a cycle.

Field station equipment- Referring to Fig. .l

the eld station includes a biased-to-neutral current at the beginpolar line relay F2 and its repeating relays FP2,

SA2 and SB2, which operate in a similar manner to corresponding relays in the control office, eX- cept that relay F2 `is a polar relay while the corresponding relay in the control cnice is a neutral relay. Relay SB2 is a repeater of relay SA2.

The eld'station includes a bank oi stepping relays IV2, 2V?,V LV2 and the associated halt-step relay VPZ operating substantially in synchronism with corresponding relays at the repeater station in response to impulses applied to control line CLl and received by relay F2. The detailed circuits for operatingthe stepping relay bank and the line repeater relays are not shown since they may be the same as for corresponding'relays in the control ofce and at the repeater station, with the exception that relay LV2 is released in the same manner as relay LV in the control oi-Tice, that is at the end of each cycle. It is thus believed obvious that the line repeaterrelays and the stepping relays operate in response to the operation ofl relay FP2 by means of circuits which are not shown but merely indicated by dotted line connection tions for the transmission of Relays PB2 and BF2 are similar to relays PB1 and PF1 at the repeater location. Relays PB2 and PF2 are controlled locally in accordance with local jumper connections and the positions of local relay contacts. They function to condition the indication line ILl in accordance with the indications to be transmitted during the different periods of a cycle as will be pointed out in detail.

Lock out relay L02 is picked up in response to a field start condition at the illustrated station and it functions to energize indication line IL1 for initiating a cycle of operations for the transmission of indications from the associated station. Relay L02 furthermore locks out distant field stations so that they are ineffective to apply impulses to the indication line circuit during a cycle of operations for the transmission of indications from the illustrated iield station.

Resistance IR2 is a compensating resistance for compensating for the resistance of the lower winding of .relay L02 which is removed from the indication line circuit after the lock out period. Resistance 2R2 is a compensating resistance to compensate for the value of resistance in the indication line circuit which is disconnected when a particular eld station is transmitting. When the illustrated field station is transmitting, the indication line IL1 is connected to the indication return line IRl by way of resistance 2R2, which resistance is of the proper value to compensate for the resistance of the indication line circuit which would be completed at the end station of a series of field stations connected to the indication line circuit.

Track switch TS is illustrated as being controlled by switch machine SM in response to the operation of switch machine relay SMR. The occupied and kunoccupied condition of the illustrated track section is repeated by track relay T in the usual manner.

The control of the signals at the illustrated station has not been shown since the control of the switch machinemay be considered typical of the manner in which additional steps of the cycle function to control signals in response to additional impulses. RelayV M is the usual signal repeating relay which, when lde-energized as shown, indicates that all signals associated with the illustrated track section are at stop and when energized indicates that some signal is clear.

Change relay CH2 is normally energized and is dropped (circuits not shown), in response to a changed condition at the associated eld station for initiating the system into a cycleV of operaindications.

The station selection portion of the system is not illustrated since this feature is immaterial for an understanding of the present invention. Station selection may be provided as explained in detail in the abovementioned application Ser.

No. 640,062. .It need only be mentioned here that station relay SO2 is picked up at the beginning of a control or duplex cycle and remains up throughout the cycle at this station only when controls are to be transmitted to this station.

GENERAL OPERATION For convenience the control line circuit and the indication line circuit extending from the control oflice to the repeater stationl will be referred to as the primary controlfline circuit and the primary indicationline circuit respectively. The control line circuit and the indication line circuit extending from the repeater station to the distant field station will be referred y the control line impulses Y mitting indications originating "cations are being handled by the to as the secondary control line circuit and the secondary indication line circuit respectively. It will be understood that one or more eld stations such as shown in Fig. 3 may be interposed in the primary and/or secondary line circuits.

The repeater station of the present invention comprises a stepper and a storage portion. The stepper portion comprises the relays necessary to enable the repeater station to follow the cycles sent out from the control ofce and to repeat received from the control oice. The stepper portion also includes relays necessary to enable the repeater station to respond to the secondary indication line impulses received from distant iield stations and also to impulse the primary indication line circuit in order to transmit indications to the control oiiice.

The storage portion of the repeater station includes relays which enable the repeater to store indications received until it has an opportunity to transmit them to the control oiiice. The repeater station has its own control line battery CB1 and indication line battery IB1 which furnish the energy for the secondary control and secondary indication line circuits respectively.

In the event that any one of the eld stations connected to the secondary line circuit has new indications to transmit to the control cnice, the

transmitting eld station rst transmits these indications to the repeater station where they are stored. When a set of indications has been stored in the repeater no other indications can be transmitted to the repeater until it has transmitted the stored indications to the control oiiice, which it does on the cycle following the storage cycle, unless some superior eld station connected to the primary line circuit takes the line.

If there is a set of indications stored in the repeater station there is also a start condition stored in the repeater station which will remain eiective until the repeater station is successful in transmitting its stored indications to the control oice.

Indications can loev stored in the repeater station or transmitted from the repeater station to the control oiice by duplex operation, or if the system is not operated for controls a start is initiated automatically for the purpose of transnected to the secondary line circuit.

The precharging .feature for the secondary indication line circuit is provided at the repeater station and functions in the same manner as the precharging feature oflice for the primary indication line circuit.

'I'he stepping and preconditioning of indications and other detailed operations are performed in much the same manner as in an ordinary control office and iield station with the exception that; first, when the repeater station is storing indications the stepping at the repeater station follows the line relay of the secondary line circuit, that is relay FNI, and when the repeater station is transmitting stored indications to the control oiiice the stepping at the repeater station follows the line relay of the primary control line circuit, that is relay F1. Second, when no indirepeater station, no stepping takes place at the repeater station since only the line relays F1 and FNI, the code sending relays PC1 and N01 and the line repeating relays SAl and SB1 operate.

The lock out feature at the repeater station at a station conl.

employed at the control functions the same as at an ordinary iield stav` tion. The repeater station is inferiorl to all stations connected ,to the primary line circuits, which are located nearer the control oiiice,.and the repeater station is superior to all eld stations connected to the secondary line circuits. Thus the lock out feature,.superiority, etc., of the field locations-.connected to the secondary line circuits arel the same as for a control office and a series of eld stations, the repeater station representing the control oice for the group- Qne or more repeater stations may be used as required. If more than one repeater station` is used Vthe controlsrare repeated in the same `manner. as., illustrated yingfthe accompanying drawings Without any storage feature, Whilethe indications` are stored `rst in the repeater station of the group originating the start condition, then in theA next repeater station and .finally transmitted tothe control ,office if the repeater stations are used-to extend the vmain/circuit. If the repeater stations are'used to.v handle branch lines extending from, a main line without repeaterstationsin Athe main line, then the `repeater stations transmit directly tothe control oice subject to thegeographic; superiority, butwithout the necessitypf transferring.; stored indications to any otherrepeaterstation. a f, Y The line circuits of a selector system such as r disclosed in the above mentioned application Ser.

. indication return conductor No. 640,062 comprise a Acontrol linecircuit including control line conductor CL and control return `conductor CRfand an indication line circuit including indication line conductor IL and 1R..V 4,'Ihesetwo line circuits correspond Vto 'thev control line circuit including conductors I and I2 yand theindication'linefcircuit including conductors I4 and vll in the above mentioned prior application. In a system of this character the control; line conductor CL is connectedv to the control return, con-y ductor CR.-V at the ,last field station associated with the primary line circuit, with the line relays of` any field station or stations between the re,- peater stationand the control oliice, as -well as the linerelays Vat-the control oiceand at the repeater station connected in, series with the control line wire.,

The primary line circuit is energized with positiveand negative impulses from a control line battery in the control oilce for the purpose of transmitting controls and for the purpose of causing the synchronous step-by-step operation at the controloilice and at the stations as will be later explained.

The primary indication line circuit is energized from, an indication line, batteryV in the control office, having includedv therein 4`at the control office message receiving relays, MF and MB which are controlled through trontand back contacts Yrespectively of relays Fl" and ZEP, as well as through` `contacts of relays PC and NC. The primary indication' line conductor IL extends to all of the iield stations connected to the` primary line `circuits and normally includes a back Contact, such as back contact 255 of relay LO2 of Fig. 3, at any station located between the oi'lice and the repeater station. In the present embodiment the primary indication line conductor terminates at `front contact ist of relay L01 at the repeater station. 1w i When a particular field stationv is transmitting= the lock outl relay at the associated station is picked up thereby rendering the open or closed conductive condition of the` primary indication line circuit with which the transmitting station is associated, dependent upon the control of either a relay similar to relay PE2 or PB2 of Fig. 3 in accordance with whether the primary control line circuit is energized or deenergized. It will be understood that the above discussion assumes that one or more field stations are connected to the primary line circuits between the repeater station and the control ollice.

A similar condition exists with regard to the secondary control and indication line circuits extending from the repeater station to the distant eld station or stations, that is the secondary control vline circuit includes `line relays at these distant stations with the control line conductor CL1 permanently connected to the return line conductor CB1 at the end station. The lock out arrangement and the conditioning of the secondary indication line circuit by the PB2 and PE2 relays associated with the secondary in.- dication line circuit is similar to the functions of corresponding relays associated with the primary indication line circuit, with the secondary indication line circuit normally open ended at the last station.

DETAILED OPERATION Normal marittima-With the system in its normal condition as indicated in the accompanying drawings, the primary control line circuit "I' and the secondary control line circuit are both deenergized. The primary indication line circuit and the secondary indication line circuit are both normally held open. All relays in the control oflice and at the repeater station are normally deenergized. All relays at the ield station (Fig. 3) are likewise normally deenergized with the exception of track relay T which is illustrated in its picked up condition, since it is assumed that the associated `track section is unoccupied. Change relay CH2 is likewise illustrated in its picked upcondition since it is assumed that a field start has not beenv initiated.

For convenience in describing the operations 1 which follow, the control line circuits will be referred to as on periods, while the deenergized or time space periods between impulses will be referred to as ofi periods. The system will be described as stepping through cycles, each comprising a conditioning on period, a rst off period, a rst on period, a second oir period, a second on period and a third clearing out off period.

Manual start-It will rst be assumed that the operator in the control office desires to move track switch TS at the eld station, illustrated in Fig. 3i, from its normal locked position to its reverse locked position. It will be assumed that the illustrated eld station responds to a code combination of (-1-) and on the rst two steps of the communication system. It will also be assumed that the trackswitch is operated to its reverse position in response to a impulse on the third step of the system.

With the system in its normal condition the actuation of starting button SB in the control oirlce is effective to pick up relays C and CD for initiating a control cycle. Since the detailed circuit arrangement for controlling the VC and CD relays is immaterial for an understanding of the present invention it has been omitted from the present disclosure, but this circuit arrangement may be the same as disclosed in the above mentioned application Ser. No. 640,062. It will be understood that only one CD relay can be picked the energized or impulse periods of up at anyone time and only at the time system is in its normal condition.

VThe picking up of relays CD and C closes a circuit Vfor picking up relay PC which extends fi'om'K-Il), back Contact d0 of relay E, front con-V tact 4I of relay C, back contacts 43 and 44 of relays 2V and IV respectively, conductor 45, front contact 46 of relay CD, code jumper 5, PC bus 4l and winding of relay PC to Y impulsing and stepping operations-The pickthe ' ing up of relay PC energizes the primary control line circuit with a impulse to mark the beginning of the conditioning on period. This circuit extends from the (I-) terminal of battery CB, front contact 5| of relay PC, back contact 5t of relay NC, winding of relay F, primary control line conductor CL, winding of relay F1, primary control return conductor CR, back contact 50 of relay NC and front contact 5310i relay PC to the terminal of battery CB.

This energization 'of the primary control line circuit picks up relay F and positions the polar contacts of relay F1 to the right. Relay F closes an obvious pick-up circuit for relay FP at its front contact 61, relay FPcloses an obvious pickup circuit for relay EFP at its front contact 63 and relay EFP closes an obvious pick-up circuit for relay SAat its front contact 59.

Relay F1 closes an obvious pick-up circuit for relay PC1 at contact |61 in its right hand dotted position. Relay F1 closes a pick-up circuit for relay SA1 which extends from contact |60 of relay F1 in its right hand dotted position, .back contact IGI of relay FCl, back contact |62 of relay L01 and Winding of relay SA1 to Since neither relay F01 nor relay L01 is picked up during a control cycle, the above described circuit for relay SA1 is intermittently energized by the intermittent operation of contact I 60 of relay Fl in response to the control impulses applied to the primary control line circuit, which maintains relay SA1 picked up until the end of the cycle. Relay SA1 closes an obvious pick-up circuit for relay SB1 at its front contact |63 which maintains relay SB1 picked up until the end of the cycle.

The picking up of relay PC1 energizes the secondary control line circuit with a impulse over a circuit extending from the (-l-) terminal of battery CB1, front contact I5I of relay PC1, back contact |54 of relay NC1, winding of relay llNl, control line conductor CLI, winding of relay F2, control return conductor CRl, back con' tact |50 of relay NC1 and front contact |53 of relay PC1 to the terminal of battery CB1.

Relay FNl is picked up over the secondary control line circuit and relay F2 actuates its polar contacts to the right. Since relay F01 at the repeater station is not picked up during a control cycle the operation of relay FN1 during such a cycle is ineiective because of open front con tact I 64. Y

At the field station, the actuation Vof contact 26IV of relay F2 to the right closes an obvious pick-up circuit for relay FP2.V Although the detailed circuits are not showin Fig. 3, in ac-V cordance with the operation of the system disclosedin the above mentioned application Ser. No. 640,062, the conditioning (-I) impulse applied to the secondary control line effects the pick-up of the station relays at a portion of the eld stations, such as relay S02 of Fig. 3. Thus, due to the actuation of contact 2I4 of relay F2 to the right, it will be assumed that relay S02 is picked up and remains in its picked up condition in response to the station selecting impulses applied to the line circuits for selecting the station illustrated in Fig. 3, so that the rst control impulse following station selection will be eiective at Athe illustrated field station due to closed front contact 2| 5 of relay SO2.

As above mentioned the detailed circuits for controlling relays SA2, SB2, VP2, IV2, 2V2 and LV2 at the eld station have been omitted, since this control may be elected in the same manner disclosed in the above mentioned application Ser. No. 640,062 and indicated in the present drawing by dotted line 265. 1

During the impulsing of the primary control line circuit which follows, the stepping relay bank at the repeater station is not operated because of open front contacts |52 and |55 of relays L01 and PC1 respectively.

The energization of the primary and secondary control line circuits as above described is elective to provide the lconditioning on period of the cycle. During this on period relay VP in the control oce is picked up overa circuit ex tending from front contact 'II of relay SA, front contact 'I2 of relay 2FP, back contacts 85 and I3 of relays 2V and IV respectively and winding of relay VP to Relay VP closes a rst stick circuit for itself extending from front contact II of relay SA, front contact I4 of relay VP, back contacts and 'I3 of relays 2V and IV respectively and winding of relay VP to The picking up of relay VP closes an energizing circuit for relay E which extends from front contact of relay SA, back contacts 3| and 32 of relays 2V and IV respectively, front contact 33 of relay'VP and winding of relay E to The picking up of relay E opens the circuit of relayiPC at its back contact 40. Relay PC drops and opens the control line circuit to mark the end of the conditioning on period and the beginning of the first olf period. This drops relays F, FP and 2FP in sequence in the control office. Relays F1 and PC1 at the repeater station are de-energized in sequence, the dropping of relay PC1 deenergizing the secondary control line circuit which is effective to drop relays F2 and FP2 at the field station. 0f course relay FNl responds to the impulses in the secondary control line circuit but since this relay is ineffective during a control cycle its operation will not be further mentioned during the description of the control cycle operation.

'Ihe dropping of relay 2FP in the control office closes a circuit for picking up relay IV which extends from (-1-) front contact 'I5 of relay SA, back contact 'I6 of relay 2FP, front contact 'I'I of relay VP, back contact 'I8 of relay 2V and winding of relay IV to Relay IV closes a stick circuit for itself extending from (f-), front contact 'I5 o f relay SA, front contact 'I9 and winding of relay IV to This stick circuit for relay IV is maintained energized until relay SA is dropped at the end of the cycle. It will be obvious that relays 2V and LV, when picked up, close similar stick circuits for themselves at their front contacts 83 and 84 respectively and it will not be necessary to point out the closure of these stick circuits again during the operation of the system, since these stick circuits are likewise maintained energized until the end of the cycle.

'I'he picking up of relay IV opens the first stick circuit of relay VPy at back contact 13, but prior toI this a second stick circuit is closed for relay VP which extends from front contact acetico 1I of relay SA, back contact 12 of relay` 2FP, front contact 85 and winding of relay VP to The picking up of relay IV de-energizes relay E at back contact 32 and the dropping of relay E picks up relay NC over a circuit extending from back contact l5 of relay E, front contact 4I of relay C, back contact i3 of relay 2V, front contact 4i of relay iV, conductor 56, front contact 51 of relay CD, jumper 6, NC bus 48 and winding of relay NC to l The primary control line circuit is therefore energized with a impulse over a circuit which now extends from battery CB through back contacts 5I and 53 oi' relay PC and front contacts 5@ and 5iof relay NC, which contacts reverse the connection of the battery applied to the primary control line circuit from that previously pointed out.

The energization or" the primary control line circuit effects the picking up of relays F, FP and 2FP in the control office, positioning of the polar contacts of relay F1 at the repeater station to the left and the picking up of relay NCl over an obvious circuit closed at contact |61 of relay F1 in its left hand dotted position. With relay NC1 picked up and relay PC1 down the secondary control line circuit is energized with a impulse.

The picking up of relay ZFP in the control oii'ice drops relay VP because the first stick circuit for relay VP is open. at back contact 13 of relay IV and the second stick circuit for relay VP is open at back contact 12 of relay ZFP. The dropping of relay VP closes a circuit for picking up relay E which extends from (-I) iront contact 9i! of relay SA, back contact 3l of relay 2V, front contact 32 of relay IV, back contact 33 of relay VP and Winding of relay E to the primary control The picking up of relay E de-energizes the above traced circuit for relay NC which drops and de-energizes the primary control line circuit to mark the end of the first on period. Relays F, FP and are dropped in sequence and relay 2V is picked up over a circuit extending from front contact 15 of relay SA, back contact 15 of relay liFP, back contact 11 of relay VP, front contact 32 of relay IV and winding of relay 2V to The picking up of relay 2V de-energizes relay E at back Contact 3l and the dropping of relay E energizes relay NC which in turn energizes line circuit to mark the beginning of the second on period.

^ Relays F, FP and 2FP are picked up in sequence and relay VP is picked up over a circuit extending from iront contact 1I of relay SA, front contactJ 12 of relay iront contact 85 of relay 2V and winding relay VP to Relay VP again completes and prepares its stick circuits which are believed to be obvious and unnecessary to be pointed out again.

The picking up of relay VP energizes relay E over a circuit extending from (-I-), front contact Si! of relay SA, iront contacts 3l and 33 of relays 2V and VP respectively and winding of relay E to The picking up of relay E de-energizes relay NC which drops and de-energizes the primary control line circuit to mark the end of the second on period and the beginning of the third or releasing out ofi period. Relays F, FP and 2FP are dropped in sequence and relay LV is picked up over a circuit extending from front contact 15 or relay SA, back contact 1E of relay ZFP, front contact i1 of relay VP, front contact 18 of relay 2V and winding oi relay LV to The picking up of relay LV does not change the circuit condition of relay E, therefore this relay remains up, the PC and NC relays remain down and the primary control line circuit remains deenergized so that relay ZFP remains down for a suiiciently long period to drop relay SA and clear out the circuits. The dropping of relay SA de-energizes relays E, VP, IV, 2V and LV` by the opening of its front contacts 90, 1I and 15. The dropping of relay SA also de-energizes relays CD and C, by circuits not shown in the present disclosure.

When relay 2V was picked up during the second ofi period as above described, its contact 43 shifted the energizing circuit from conductor 56 to 5I, which extends this circuit through front contact 62, lever SML in its right hand dotted line (reverse) position and NC bus 43 to the winding of relay NC. This is effective to make the third impulse applied to the primary control line circuit during the second on period It will be understood that lever SML in its left hand (normal) position would energize relay PC instead of relay NC, so that the switch control impulse would be instead of Referring to the field station illustrated in Fig. 3 it will be recalled that the (-I) and irnpulses applied to the primary control line circuit are repeated into the secondary control line circuit by the operation of relays PCl and NC1 respectively at the repeater station. It will be understood that the conditioning and the first impulses which were assumed to be and because of the connections of jumpers 5 and 6 in the control o-iiice, were effective to select the station illustrated in rig. 3 by maintaining relay SO2 in its energized condition.

After the station is selected the third impulse (second 0n) which was applied to the secondary control line circuit in response to the impulse applied to the primary control line circuit (because lever SML was assumed to be in its reverse position), positions contact 2 It of relay F2 to the left. This closes a circuit for energizing relay SMR extending from (CN), winding of relay SMR, front contact 2 i6 of relay 2V2, front contact 2 I5 of relay SO2 and contact 2 I4 of relay F2 in its left hand dotted position to (B This positions contact 256 of relay SMR to its left hand dotted position for controlling the operation of the switch machine for actuating the track switch to its reverse locked position.

It will be apparent that a impulse received at the iield station during the second on period would position contact 2M of relay F2 to the right, which would energize relay SMR in the i opposite direction for positioning contact 250 to the right for controlling the switch machine to actuate the track switch to its normal locked position.

It will be understood that relays F2 and FP2 which follow the impulses in the secondary control line circuit remain cle-energized at the end of the cycle for dropping relays SA2, S32, the stepping relays and relay SO2. Likewise, relays SA1 and SBl at the repeater station are dropped during the clearing out period because contact i60 of relay F1 remains in its neutral position for a comparatively long interval of time when the secondary control line circuit is cle-energized at the end of the cycle.

INnrcAfiIoNs Automatic start-Assuming the system to be in its normal condition when a change in condition occurs at a iield station, for example the station illustrated in Fig. 3, relay CH2 is dropped in response tosuch a change in condition. This closes a circuit for picking up relay L0.2 which extends from (Jp), back contact 261 of relay FP2, back Contact 238 of relay SB2, back Contact 253 of relay SA2, upper winding of relay L02 and back contact d of relay CH2 to Relay L02 establishes a substitute circuit to at its front contact 255 which is independent of back contact 25d of relay CH2.

The secondary indication line circuit is enerv gized in response to the picking up of relay L02 iii) over a circuit extending from the terminal ofV battery IB1 (see Fig. 2C), lower winding of relay MB1, back contacts |58 and |59 of relays SB1 and LV1 respectively, indication line conductor IL1, front contact 255 of relay L02, back contact 212 of relay SB2, lower winding of relay L02, resistance R2 and indication return conducto-r TR1 to the terminal o-f battery IB1.

Relay MB1 Vis picked up over the above described circuit and a circuit is closed for picking up relay FC1 which extends from (-1-), front contact |65 of relay MB1, back contact IBS of relay SB1 and winding of relay FC1 to The picking up of relay FC1 closes a circuit for picking up relay L01 which extends from back contacts |68, |59 and |10 of relays FP1, SB1 and SA1 respectively, upper winding of relay L01 and front contact |1| of relay FC1 to The picking up of relay L01 closes the primary indication line circuit over a circuit eX- tending from the terminal of battery IB (see Fig. 1B), lower winding of relay MB, back contacts S28 and 91 of relays PC and NC respec tively, back contacts $4 and 92 of relays FP and EFP respectively, front contacts 9| and 8| of relays SA and FC respectively, indication line conductor IL, front contact |56 of relay L01, back Contact i12 of relay SB1, back contact |13 of relay FP1, lower winding of relay L01 and indication return conductor IR to the terminal of battery IB.

The closing of the primary indication line circuit picks up relay MB which in turn closes a circuit for picking up relay FC at its front contact 33. The pick-up and stick circuits of relay FC have been omitted from the drawings for the sake of simplicity, since the detailed operation of this relay is immaterial for an understanding of theY present invention, it being understood that these circuits can be the same as disclosed in the above-mentioned application Ser. No. 640,062..

Repeater stepping opwarmen-The picking up of relay FC closes a circuit for picking up relay NC which extends from (-l-), back contact 4|) of relay E, back contact 4| of relay C, front contact of relay FC, NC bus 48 and winding of relay NC to It will be assumed that this is a cycle for the transmission of indications alone (not a duplex cycle), so that relay C remains down and relay FC remains picked up for maintaining relay NC energized throughout the cycle. This provides a series of impulses applied to the primary control line circuit over a circuit extending through front co-ntacts and 54 of relay NC and back contacts 5| and 53 of relay PC.

The energization of relay NC energizes the primary control line circuit with a conditioning impulse which effects the picking up of relays F, FP, ZFP, SA, VP and E in the same manner as previously described.

The picking up of relay E drops relay NC which de-energizes the primary control line circuit to effect the dropping of relays F, FP, EFP and the picking of relay |V, which in turn drops relay E for again picking up relay NC which in turn energizes the primary control line circuit with a impulse,

It is believed unnecessary to pointout in detail how the step-by-step operations in the control oice and atthe field station (Fig. 3) are effected, since these operations are the same as already described in connection with a control cycle, with the above mentioned exceptionthat the primary control line circuit is energized with a series of impulses. This positions the polar contacts of relay F1 at the repeater station to the left for each impulse which picks up relay NC1 to repeat a series of impulses into the secondary control line circuit.

During the step-by-step operations relay FN1 at the repeater station follows the impulses applied to the secondarycontrol line circuit. Relay MB is dropped when relay EFP is dropped during the rst olf period of the cycle. The stick circuits for relays MB and MF will be later pointed out. Since the primary indication line circuit is not energized during this rst indication cycle relay MB (as well as relay MF) remains down throughout this first cycle.

The conditioning impulse applied to the primary control ondary control line circuit with a impulse for picking up relay FN1. Relay FN1 closes a circuit for picking up relay FP1 which extends from front contact |14 of relay FN1, front contact |66 of relay FC1 and winding of relay FP1 to Relay FP1 closes a circuit for picking up relay 2FP1 which extends from front contact |15 of relay FC1, winding of relay 2FP1 and front contact |16 of relay FP1 to The picking up of relay FP1 opens the primary indication line circuit at back contact |13 and since relays PF1 and PB1 are not operated during this first indication cycle the primary indication line circuit remains open throughout the cycle because of open front contacts 11 and |18 of relays PF1 and PB1 respectively.

The picking up of relay FP1 opens the local energizing circuit including the upper winding of relay L01 at back contact |68 and, since the energizing circuit through the lower winding of relay L01 is open at back contact FP1 and back contact |19 of relay FC1, relay L01 is dropped. This opens the primary indication line circuit at front contact |56, at which point it remains open throughout this rst indication cycle.

Relay FC1 is stuck up throughout the first indication cycle over an obvious circuit to at front contacts |41 and |415 in multiple of relays SA1 and 2FP1 respectively. Relay MB1 is dropped during the conditioning on period in response to the opening of the secondary indication line circuit by the picking up of relay SB2 at the station of Fig. 3. This is because the secondary indication line circuit is opened before relay SB1 is picked up to close the stick circuit for relay MB1 at front contact |38.

From the above it will be observed that a change in condition at a ield station is effective through a cycle during which the primary indication line circuit is not conditioned. It will now be explained how the secondary indication line circuit is conditioned for transmitting indications to the repeater station where they are received and stored, after line circuit energizes the sec- |13 of relay 4tioning on applied to which a second indication cycle is effected for the transmission oi these stored indications to the control oiiice.

The picking up oi relay 2FP1 as above described. closes a circuit for picking up relay SA1 which extends from (J,), iront contact |58 of relay FP1, conductor 25|), front contact |85 of relay FC1, front contact iiil of relay 2FP1 and Winding of relay SA1 to Relay SA1 closes an obvious pick-up circuit for relay S131 at its front contact |63.

Relay VP1 is now picked up over a circuit extending frorn (-1-), front contact |51 of relay SB1, front contact |55 of relay FC1, front contact |82 of relay FP1, back contact |33 of relay |V1 and Winding of relay VP1 to Relay VP1 closes a first stick circuit for itself including the above described circuit and by vvay oi` front contact |85 of relay VP1, which circuit is independent of contacts |55 and |82 of relays FC1 and FP1 respectively.

In response to the termination of the condithe secondary control line circuit, relays FN1, FP1 and 2FP1 are deenergized in sequence. It will be observed that stepping at the repeater station is controlled by contact |15 of relay FN1, contact |55 of relay F1 being ineffective because of open contact |E| of relay FC1.

A circuit is now closed for picking up relay |V1 which extends from iront contact |51 of relay SE1, front contact |55 of 'relay F01, back contact |32 of relay FP1, iront contact |555 of relay VP1, back contact |55 of relay 2V1 and winding of rela?,T |V1 to Relay FP1 closes a second stick circuit for relay VP1 to prevent this relay being dropped during the 01T period, which circuit extends from (-l-) iront contact |81 oi relay SE1, back contact |88 of relay FP1, iront contact |89 and Winding of relay VP1 to The picking up of relay |V1 closes a stick circuit for itself extending from front contact |51 of relay SB1, iront contact 95 and winding of relay |V1 to Relay E1 is picked up during the conditioning on period over a circuit extending from iront Contact Veil oi relay SB1, iront contact |92 of relay F01, back contact |53 of relay ZV1, back contact iifi or" relay |V1, front contact |95 oi relay VP1 and winding of relay E1 to in response to the picking up of relay |V1 during the first ofi period the above described circuit for relay E1 is opened at back contact itt which effects the release of relay E1.

In response to the termination of the first ofi period and the beginning oi the first on period applied to the secondary control line circuit, relays FN1, FP1 and 2FP1 are picked up in sequence. Relay VP1 is dropped during this on period because its first stick circuit is open at back contact |133 of relay |V1 and its second stick circuit is open at back contact |88 of relay FP1. Relay E1 is now picked up over the above described circuit which now extends through back contact |95 oi relay VP1 and front contact |S of relay |V1.

In response to the termination of the rst "on period and the beginning of the second off period relays FN1, FP1 and 2FP1 are dropped in sequence. Relay ZV1 is picked up over a circuit extending irorn iront contact |51 of relay SB1, iront contact of relay FC1, back contact |62 oi relay FP1, back contact |85 of relay VP1, iront contact |55 of relay |V1 and winding of relay ZV1 to Relay ZV1 closes an obvious stick circuit for itself at its front contactv|91. Relay E1 is dropped during this ofi period because of open back contact |93 of relay ZV1.

In response to the termination oi the second ofi period and the beginning of the second on period relays FN1, FP1 and 2FP1 are picked up in sequence. Relay VP1 is now picked up over a circuit extending from (-1-), front contact |51 of relay SB1, front contact |55 of relay FC1, front Contact i82- of relay FP1, iront contact |98 of relay 2V1 and winding of relay VP1 to Relay VP1 closes its rst stick circuit at its front contact |84 and prepares its second stick circuit at iront contact |89, which circuits are obvious from the previous explanation. Relay E1 is picked up over the above described pick-up circuit which now includes front contact |93 of relay ZV1 and iront contact |95 of relay VP1.

In response to the termination of the second on period and the beginning of the third oit period relays FN1, FP1 and 2FP1 are dropped in sequence. A circuit is now closed for picking up relay LV1 which extends from (-1-) front contact |51 of relay SB1, front contact |55 of relay FC1, back contact |32 of relay FP1, front contact |85 of relay VP1, front contact |85 of relay 2V1 and lower winding of relay LV1 to Relay LV1 establishes a stick circuit for itself which extends from back contact |99 of relay L01, iront contact |49 and upper winding of relay LV1 to Since relay L01 remains down throughout this first cycle and is not picked up until the beginning of the second indication cycle or possibly a later cycle when the repeater station is allowed to transmit, relay LV1 is maintained stuck up during the clearing out period between cycles by a circuit extending to at back contact |48 of relay ZV1.

The third oir period marks the end of the first indication cycle, since there are no further impulses applied to the primary control line circuit in the control oiiice, so that relay 2FP1 remains down for a period of time sucient to allow all slow repeater relays to release. Relay SA1 drops which in turn deenergizes relay SB1 at open front contact |63 and the dropping of relay SB1 deenergizes relays VP1, |V1 and ZV1 at open front contacts |51 and |81. Relay SA1 deenergizes relay F01 at open front contact |41.

The opening of front contact |92 of relay F01 deenergizes relay E1.

Transmission of indications to `repeater station.-During the operation of the rst indication cycle above described, indications are transmitted from the iield station illustrated in Fig. 3 to the repeater station illustrated in Figs. 2A, 2B and 2C by the conditioning of the secondary indication line circuit. Relays LOZ and SB2 remain picked up at the eld station throughout this first indication cycle so that the circuit of the secondary indication line including front contact 212 of relay SBZ, can be energized or deenergized during both the on" and off periods as selected by contact 213 of relay FP2 in accordance with the closed or open conditions of contacts 295 and 29| of relays PF2 and FB2 respectively. l

During each ofi period in the series ofv impulses the (-1-) terminal of indication battery 1B1 (Fig. 2C) is connected tosecondary indication line conductor IL1 through the lower winding of relay MB1 and current flow in the secondary indication line circuit is dependent upon front contact 29| of relay FB2. More specically, relay PB2 is the code transmitter for of the series. Assuming jumper 289 at the iield station to be connected to (-1-) as shown, relay FB2 is picked up during the conditioning on period over a circuit extending from (-1-), jumper 239, back contacts 295 and 286 of relays IV2 and 2V2 respectively, iront contact 288 of relay FP2, winding of relay FB2 and front contact 289 of relay L02 to The picking up of relay FB2 provides one of a choice of two off indication codes.

When relay FP2 is dropped during the first on period relay FB2 is stuck up over a circuit extending from (-1-), iront contact 299 of relay FB2, back contact 283 oi relay FP2, winding of relay FB2 and front contact 289 of relay L02 to When relay FP2 is picked up during the rst on period the above described stick circuit is opened and the energization of relay FB2 is dependent upon a circuit extending through front contact 285 of relay W2 for the second olif indication, to contact 292 of relay T, which being open illustrates the alternate choice of an off indication. Relay FB2 will be deenergized.

During the second on period the energization of relay FB2 is dependent upon the energization of a circuit including front contact 286 of relay 2V2, which circuit has not been shown because the above examples are typical of the choice of two conditions for the transmission of oli indications.

With relay FB2 picked up during the conditioning on period and stuck up throughout the rst 01T period as above described, the secondary indication line circuit is closed as will be presently pointed out. This indication line circuit Was opened during the conditioning on period when relay SB2 opened its back contact 272.

The lock out period for maintaining relay L02 energized extends from the time of the picking up of relay FP2 and the consequent opening of its back contact 297 until the picking up of relay SA2 and the consequent closing of its front contact 253, during which period relay L02 is dependent for its energization on line current received from battery IB1 at the rep-eater station and through its lower Winding. In the event that some other station superior to the station of Fig. 3 opens the secondary indication line circuit during this lock out period, then of course relay L02 is dropped during the lock out period and it cannot be picked up again until the start of another cycle. With relay L02 maintained picked up during the lock out period, then when relay SA2 closes` its front contact 253, relay L02 is stuck up over a circuit including its upper winding and its front contacts 255 and 258 in series with iront contact 253 of relay SA2. Thus relay L02 is maintained picked up until relay SA2 drops at the end of the cycle.

During each on period the secondary indication line circuit remains open or is closed depending upon contact 299 of relay PF2. For example, assuming that code jumper 282 is connected to (-1-) as shown in Fig. 3, then relay FP2 is picked up during the rst off period over a circuit extending from (-1-), jumper 282, back contact 294 of relay 2v2, front contact 295 of relay VF2, back contact 297 of relay FP2, winding of relay PF2 and front contact 289 of relay L02 to When relay FP2 is picked up during the first on period relay PF2 is stuck up over a circuit extending from (-1-), iront contact 298 of relay PF2, front contact 297 of relay FP2, Winding of 4relay PF2 and front contact 289 of relay L02 to The abovev illustrates one choice of an on indication Whereby relay P1212 is picked up. The other choice of an on indication is effected by the Ideenergization of the circuit including the Winding of relay PF2 and back contact 227 of relay FP2. The first choice on indication again energizes relay PF2 in the second oi period, While the other choice on indication does not eiect the picking up of relay PF2 during an oil period so that it is down throughout the following on period.

Since relay M is assumed to be deenergized and its back contact 29! closed, the econd on indication is the same as the iirst on indication because relay BF2 will be picked up during the second olf period over a circuit extending through back contact 29! of relay M, iront contact 293 of relay lV2, back contact of relay VP2 and back contact 297 of relay FP2 to the winding of relay PF2. The third on indication is selected through front contact 2913 of relay 2v2, which circuit is not shown since it is believed the above examples are suiiicient to illustrate the choice of two on indications which may ce provided at each step of the system,

It will now be explained how the conditioning of relays FB2 and PF2 effects the closing and the opening of the secondary indication line circuit for transmitting indications to the repeater station Where they are received and stored.

From the above discussion of the conditioning of the FB2 and PF2 relays it will be observed tha' relay FF2 is positioned during an oil period in accordance with the indication it is to transmit in the next on period, While relay FB2 is positioned during an on period in accordance with the indication it is to transmit in the next olif period. Thus on each step taken by the step-by-step mechanism at the field station relays PF2 and FB2 govern the secondary indication 'ne circuit.

It will be recalled that the secondary indication line circuit was opened during the conditioning on period by the picking up of relay SB2 andthe consequent opening or its back contact 272. The dropping of relay 2FP1 at the repeater station during the iirst oli period permits current to iloW in the secondary indication line circuit (because relay FB2 is picked up throughout this off period), over a circuit extending from the (-1-) terminal of battery IB1 at the repeater station, lower winding of relay MB1, back contacts iili and l of relays P01 and NC1 respectively, back contact i152 of relay FP1, back contact lll! of relay 2FF1, iront contact M9 of relay SA1, iront contact E52 oi relay SB1, back contact 59 of relay LV1, secondary indication line conductor IL1, front contacts 256 and 272 of relays L02 and SB2 respectively, back contact 273 oi relay FP2, front contact 29! of relay FB2, resistance 2R2 and indication return conductor IRl to the terminal of battery IBI,

This energization of the secondary indication line circuit picks up relay MB1 and it is stuck up over a circuit extending from (-1-), front contact I or relay 5B1, back contact 939 of relay E1, front contact i355- and upper Winding' of relay MB1 to During the iirst on period the picking up oi relay ZFPl (before the picking upI of relay E1) closes a substitute stick circuit for relay MB1 which extends through front contact 39 of relay SE1 and front contact i3! of relay 2ER Relay MB1 is thus stuck up when picked up throughout the "on period following the off period during which it was picked up.

The picking up of relay N01 at the repeater station to mark the beginning of the iirst on period opens the secondary indication line circuit at back contact |43. This deenergizes the secondary indication line circuit and when relay 2FP1 is picked up during the rst on period the secondary indication line circuit is again energized because relay PF2 at the field station is up.

The energizing circuit for the secondary indication line circuit extendsV from the (-1-) terminal of battery IB1, lower winding of relay MF1, back contact |35 of relay PC1, front contact |36 of relay NC1, front contact |31 of relay FP1,rfront contact |l|| of relay 2FP1, front contact |4 of relay SA1, front contact |58 of relay SB1, back contact |59 of relay LV1, indication line conductor IL1, front contacts 256 and 212 of relays LO2 and SB2 respectively, front contacts 213 and 299 ci relays FP2 and PFZ respectively, resistance 2R2- and indication return conductor IR1 to the terminal of battery IB1. This eiects the energization of rel-ay MF1 and since relay E1 is picked up during this first on period, relay MF1 is stuck up over a circuit extending from front contacts |30 and |33 of relays SB1 and E1 respectively, front contact |38 and winding of relay MF1 to When relay 2FP1 is dropped during the succeeding (second) off period relay MF1 is stuck up over a circuit including back contact |3I of relay 2FP1. It will thus be observed that relay MF1 when picked up during an on period is stuck up throughout the following oif period. The dropping of relay 2FP1 during the second off period fails to close the secondary indication line circuit because of open front contact 29| of relay PB2. 1

When relay 2FP1 is picked up during the second "on period then the secondary indication line circuit is closed because relay PF2 is picked up throughout this period. It is believed unnecessary to trace the energizing circuit for the secondary indication line since it is the same as previously traced.

Since the secondary indication line circuit is not energized during the second oif period in response to the dropping of relay 2FP1, relay MB1 is dropped during this period when relay 2FP1 opens its front contact I3| because the stick circuit for relay MB1 is de-energized at open back contact |33 of relay E1 and open front contact |3| of relay 2FP1.

The energization of the secondary indication line circuit during the second on period picks up relay MF1 as previously described and this relay is stuck up for a sufcient period of time during the following off period to execute this particular indication condition. In the event that relay PF2 is down throughout the second "on period the relay MF1 is dropped when relay 2FP1 opens its back contact |3| to de-energize the stick circuit of relay MF1 before it is energized by the closure of front contact |33 of relayE1.

During the last off (clearing out) period the secondary indication line `circuit Vis de-energized by the dropping of relay NC1 and the opening of its front contact |355. Relay MF1, which was stuck up throughout the second on period, is dropped in the lclearing out period when relay SB1 drops and opens its front contact |30. Relay PFZ, which was stuck up throughout the second on period, is dropped when relay FP2 drops and opens its front contact 291 in the clearing out period.

From the above it will be observed that relay MB1 is selectively responsive during the oif periods to the energization and de-energization of the secondary indication line circuit for receiving either one of a choice of two distinctive indications, with the selected choice maintained throughout the following on period by relay MB1 either being up or down throughout this on period. Furthermore, relay MF1 is selectively responsive during each on period in accordance with one oranother choice of two indications transmitted during each on period, with relay MF1 remaining up or down throughout the following off period to register the selected indication which was transmitted and received by this relay.

Storage of indications. -Storage relays STO1 and STO3 store the off indications received by relay MB1 and storage relays STO2 and STO4 store the on indications received by relay MF1. It will be understood that additional storage relays may be provided when additional steps are used at the repeater station.

It will be recalled that relay MB1 was maintained in its picked up position throughout the first on period in accordance with the indication received in the previous o period. With relay MB1 picked up a circuit is closed during the first on period for energizing relay STO1 which extends from front contacts |20 and |2| of relays MB1 and FP1 respectively, front contact |22 of relay F01, back contact |23 of relay 2V1, front contact l2@ of relay |V1 and winding of relay STO1 to Relay STO1 closes a stick circuit for itself extendingfiom (-i-) front contact |39 of relay SB1, front contact |25 and winding of relay STO1 to Since relay MB1 is not up during the second on period relay STO3 is no-t picked up.

It will be recalled that relay MF1 is up throughout the second off period, which is effective to close a pick-up circuit for relay STO2 which extends from (-i-), front contact |26 of relay MF1, back contact |21 of relay FP1, front contact |28 of relay FC1, back contact |29 of relay VP1, front contact H0 of relay |V1 and winding of relay STO2 to Relay STO2 closes an obvious stick circuit for itself at its front contact Since relay MF1 is up during the third oi period following the dropping of relay FP1, a pickup circuit is closed for relay STO1 similar to the above described circuit for STO2, but extending through front contacts ||2 and |29 of relays 2V1 and VP1 respectively. Relay STO'1 closes an obvious stick circuit for itself at its front contact H3. From the above discussion of' the operation of the storage relays it will be apparent that the choice oi each off indication effects the energization or the de-energization of relays STO1 and STO3, while the choice of the on indications effects the energization or the deenergization of relays STO2 and STO1.

Repeating' the stored ind'catz'ons. -Recalling that relay LV1 at the repeater station was picked up during the third foi period and was not dropped when relays SA1 relays FP1, SB1 and SA1 respectively, upper windand SB1 were dropped to de-energize the other relays which were stuck ing ofrelay L01, backl contact VH of relay FC1, front contact ||5 of relay LV1 and back contactk ||6 of relay VP1 to Relay L01 establishes a stick circuit for itself by way of its front Contact |I'l which is effective after the picking up of relay VP1. At its front contact HB a stick circuitA is established through back contact H9 oirelay FC1 and iront contact |70 of relay SA1, which is eiective after the lock out period.

In'the event that there are one or more field stations connected to the primary line circuits between the repeater station and the control oihce, then the lockv out arrangement at these field'v stations is effective toy prevent the transmission of repeater station stored indications to the control ofce, in the event that indications are ready for transmission at some one of these superior field locations. The lock out feature at the repeater station is eiTective to drop relay L01 in the event that the primary indication line circuit is interrupted by a superior eld station. This feature is eieotive during the time interval between the picking up of relay FP1 and the consequent de-energization of the upper Winding of relay L01 at back contact |63 and the re-energization of this upper winding by the picldng up of relay SA1 and the consequent closure of its front contact Illl. It will be obvious that during this interval, if the primary indication line circuit is open at some superior station, then relay L01 cannot be maintained energized and it will be dropped away before relay SA1 is picked up to complete its permanent stick circuit at contact |10.

'I'he picking up o1" relay L01 previously described closes the primary indication line circuit by the closure of front contact |56 over the circuit which was previously pointed out. Following this energization of the primary indication line circuit relays MB, FC and NC in the controloice are picked up as previously described, with the picking up of relay NC energizing the primary control line circuit to start the system through a second cycle of operations. The primary control line circuit is impulsed with a series of impulses throughout this second indication cycle and relays F, FP, rFP, SA, E, NC and the stepping relay bank all operate in the manner previously described. Relay MB is stuck up until relay EFP drops in the rst ofi period to connect the lower winding of relay MB in the primary indication line circuit as later described. This stick circuit extends from front contact 60 of relay SA, front contact El; of relay 2F?, front contact 65 and winding of relay MB to Since it is assumed that no controls are to be transmitted during this second indication cycle, a,v series of impulses are applied to the primary control line circuit. Relay NC1 at the repeater station follows these impulses to transmit a series of impulses over the secondary control line circuit. These impulses applied to the secondary control line circuit eiect the intermittent operation of relays F1 and FN1 as before but, because relay F01 is not picked up during this second indication cycle, the operation of relay FN1 is not effective to control the line repeater relays because of open front contact ld. The intermittent actuation of contact |61? of relay F1 is effective to control the line repeater relays at the repeater station because of closed back contact |6| of relay FC1.

The line relays at the field stations, such as the' station illustrated in Fig. 3, are responsive to the impulses applied to the secondary control line circuit vduring this second indication cycle but, in accordance with the tem disclosed in the above mentioned application Ser. No. 640,062, stepping does not take place at these stations because neither the station selecting relays (such as relay SO2) nor the lock out relays (such as relay L02) are picked up.

The first or conditioning impulse applied to the control line circuit actuates contact |553 of relay F1 to the left which closes a circuit for picking up relay FP1 extending from'(-|-) contact |60 in its right hand dotted position, back contact |6| of relay F01, back contact |09 of relay SB1 and winding of relay FP1 to A circuit in multiple with contact i633 extends through front contact |62 of relay L01. A circuit is closed for picking up relay SA1 which extends from front contact E58 of relay FP1, conductor 200, back contact |39 of relay F01 and winding of relay SA1 to Relay 2FP1 is not picked up during this cycle because of open front contact |15 of relay FC1, but relay SE1 is picked up over an obvious circuit including iront contact |63 of relay SA1.

The intermittent operation of relay FP1 during this second indication cycle is effective to operate the stepping relay bank as previously described because of closed front contact |52 of relay L01. The system therefore steps through a cycle of operations in the manner previously described.

During this second cycle of operations, relays PB1 and PF1 at the repeater station are positioned in accordance with the positions of the storage relays and the primary indication line circuit is impulsed in accordance with the positions of relays PB1 and PF1 in much the same vmanner as described in connection with the impulsing of the secondary indication line circuit in accordance with the positions of relays PB2 and PFZ.

For example, with relay ST01 picked up and stuck up as previously explained relay PB1 is picked up when relay FP1 picks up, by means of a circuit extending from (-l-) front contact |99 of relay ST01, back contacts 0| and |92 of relays |V1 and ZV1 respectively, front contact 43S of relay FP1, winding of relay PB1 and front contact Id of relay L01 tol When relay FP1 is dropped at the end of the conditioning on period relay PB1 is stuck up over an obvious circuit including its front contact |95. This stick circuit is maintained throughout the rst off period so that relay PB1 when picked up is stuck up until relay FP1 again picks up to open its back contact |03.

The closure of front contact |03 extends the circuitv of relay PB1 by way of back contact |62 of relay .2V1 and front contact HH of relay |V1 to front contact lil@ of relay ST03, but since relay ST03 is not picked up relay PB1 will not be energized at this time. It drops because both its pick-up and stick circuits are open. When relay PB1'is not picked up during an on period it remains down throughout the following 01T period. The above illustrates how the off indications stored by relays ST01 and ST03 are effective to position relay PB1.

Recalling that relay ST02 was picked up and stuck up, the dropping of relay W1 at the beginning of the iirst off period closes a circuit for picking up relay PF1 which extends from front contact l'l of1elayST02,backcontact |98 of relay 2V1,front contact 220 of relayVP1,back contact 22| of relay FP1, Winding of relay PF1 and operation of the sys-` front contact lili of relay L01 to With relay PF1 picked up it is stuck up when relay FP1 picks up at the end of the first olf period over an obvious circuit including front contact 22! of relay FP1 and front contact 222 of relay PF1.

The dropping of relay FP1 at the end of the first on period de-energizes the above described stick circuit for relay PF1, but since relay STO*1 is picked up relay PF1 is immediately energized over a circuit extending from front contact 223 of relay STO1, front contact 224 of relay W1, back contact 22E! of relay VP1, back contact 22! of relay FP1, winding of relay PF1 and front contact lili! of relay L01 to Relay PF1 is again stuck up when relay FP1 is picked up at the beginning of the second on period. The above illustrates how relay PF1 is picked up during an oif period and maintained picked up throughout the following on period for one choice indication. It is believed obvious that the other choice indication is effected by relays STO2 orV S'IO1 being down to effect the de-energization of relay PF1 when relay FP1 is dropped so that relay PF1 will be down throughout the following on period.

Relay PB1 is picked up during the conditioning on period in preparation for the iirst off indication as one which shall close the primary indication line circuit, but this line circuit is not closed by PB1 until Vthe following off period. When relays NC, FP and 2FP are dropped in the control ofce to apply energy to the primary indication line circuit by way of back contacts 91, gli and S2 respectively, the primary indication line circuit is completed because of closed front contact lli? of relay PB1 at the repeater station.

When relay NC in the control oflice picks up and opens its back Contact 91 at the beginning of the first on period, the primary indication line is de-energized and the circuit including the primary indication` line is switched from relay MB to relay MF by way of front contacts 93 and 92 of relays FP and 2FP respectively, when'these relays are picked up during the first on period. Since reiay PF1 is up for the transmission. of an impulse over the primary indication line circuit during the first on period, the closure of iront contact 225 of relay FP1 completes the energizing circuit for the primary indication line circuit by way of iront Contact II'l of relay PF1. Then when relay NC drops and opens its front contact S5 at the beginning of the second off period the primary indication line circuit is de-energized.

Since relay PB1 is left down in preparation for a non-pulse of the primary indication line circuit for the second olii period, the dropping of relays FP and 2FP in the control oiilce are ineffective to close the primary indication line circuit with back contact el oi" relay NC closed because of open front contact liS of relay PB1.

Since relay PF1 is up in preparation for a pulse for the second on indication of the primary indication line circuit the picking up of relays NC, FP and 2FP the control office completes the primary indication line circuit because of closed front contact il? of relay PF1.

From the above it will be observed how the primary indication line circuit is pulsed or not pulsed to provide a choice of two off indications in accordance with the position or relay PB1 at each step and how this indication line circuit is pulsed or not pulsed to provide a choice of two on indications in accordance with the position of relay PF1 at each step.

This conditioning ci the primary indication line circuit eiects the energization and the de-energization of the MB and MF relays in the control oflice in exactly the same manner as described in connection with the impulsing of the secondary indication line circuit for energizing and de-ener gizing relays MB1 and VMF1 at the repeater station. Furthermore, this conditioning of the primary indication line circuit transmits codes to the control cnice where they are received by the MB and MF relays and stored on indication receiving relays in the same manner as described in the above mentioned application Ser. No. 640,-

O62. It is therefore believed unnecessary to point out in detail how, the positioning of the MB and MF relays in the office is eifective to transfer the received codesto indication storing relays.

It will be pointed out however how the MB and MF relays, when picked up in the oif and on periods respectively, are stuck up throughout the following on and off periods respectively.

When relay MB is picked up during the first off period as above described, a stick circuit is closed for this relay which extends from (+L front contact 6!) of relay SA, back Contact 63 of relay E (relay E being dropped before the indication line circuit is de-energized) front contact 65 and upper winding of relay MB to Since relay 2FP is picked up during the first on period before relay E is picked up, a substitute stick circuit is closed by way of front contact 64 of relay ZFP which is e'ective to maintain relay MB stuck up until the following olf period, when its energization is determined by the closed condition of the primary indication line circuit for the second off indication.

With relay MF picked up in the first on period as above described, a stick circuit is closed for this relay which extends from front contact 6B of relay SA, front contact 63 of relay E, front contact 66 and upper winding of relay MF to This circuit is completed through front contact 63 of relay E because relay E is picked up before they primary indication line circuit is opened to de-energize the lower winding of relay MIF. Since relay 2FP is dropped before relay E opens its front contact 63, a substitute stick circuit is closed for relay MF which extends through back contact Si of relay 2FP. When relay 2FP picks up during the second on period the stick circuit of relay MF is de-energized and relay MF is dependent upon the energization of the primary indication line circuit for the energization of its lower winding.

It is believed that the above examples relating to the stick circuits for the MB and MF relays when picked up during the first off and first on periods respectively are suicient to indicate how these relays are stuck up when picked up during other off and on periods.

At the end of the second indication cycle, during which the stored indications are transmitted to the control ofce, the last o period of the control line circuits is effective to de-energize the SA and SB relays in the control oice and at the repeater station in the same manner as previously described. The stepping relays are deenergized as previously described and the storage relays at the repeater station are dsa-energized when relay SB drops and opens rits front Contact 039, since at this time relay LV1 will have been dropped to open its front contact H4. Relay LV1 is cie-energized during the Second 011 Period by the opening of back contact 226 of relay V131. It Will be obvious that back contact |48 of 'transmitting contacts at the outlying field station and at the repeater station respectively. With this arrangement it happens that the sequence of events is such that the distributed capacity of the .indication line circuits may become discharged .so that the application of energy to these circuits may result in a temporarysurge of current which is conveniently termed the charging current. This charging current flows irrespective of `whether the line circuit is open or closed at the location from which an indication is to be received.

It has been found in some instances that the charging current that ows into an open circuited indication line reaches a peak value which is considerably greater than the current that normally flows under the stable conductive condition of the line circuit and that this charging current surge lasts for an appreciable length of time. Under these conditions the Ymessage receiving relay in the indication line circuit, for the purpose of detecting the conductive condition of the line, may be undesirably picked up by the charging current when such relay was supposed to remain down in accordance with the open circuit condiltion of the line.

vIt will be recalled that the primary indication rline circuit was not impulsed during the rst indication cycle above described because of open front contact |56 of relay L01 of Fig. 2C. Durl ing this cycle the contact arrangement comprising contacts 92, 93 and Sil of relays EFP and FP of Fig. 1B apply a charge to the primary indication line circuit at each period of the cycle, which is effective to prevent the false energization of relay MB or MF due -to the capacity of the primary indication line circuit. Of course the primary indication line circuit is maintained open through out this rst cycle so that one charge would be suiicient. However during the second cycle a repeated charge is required because the primary indication line circuit may be repeatedly discharged by a closed contact at a eid location.

YDuring the iirst indication cycle however, the secondary indication line circuit connecting the repeater station with the distant eld station is impulsed and the contact arrangement, comprising contacts |41, |31 and mi of relays 2FP1 and FP1 of Fig. 2C, is effective to precharge the secondary indication line circuit.

During the transfer from one period to another, that is from an on period to an 01T period or viceversa, there is an interval of time during which the secondary indication line circuit is not energized from indication battery IB1 and during which time the distributed capacity of the secondary indication line circuit may become discharged by reason of the closed condition of one of its controlling contacts at the eld station.

This is because the eld station apparatus is not Y permitted to change the condition of the secondary indication line circuit until after this line circuit is opened at the repeater station, which is necessary to provide that the message receiving relays MF1 and MB1 will be properly controlled. Thereafter, the transfer at the eld station occurs so that upon the closure of the secondary indication line circuit at the repeater station, the conductive circuit then established is dependent upon the governing contact at the eld station. Thus it is obvious that a charging current will iiow at the beginning of each period which follows a period during which the secondary indication line circuit has been conductively closed at the eld station, or at the beginning of a period following an interval during which the line may have been discharged for any other reason. The same discussion applies to the operation of relays MF and MB in the oice, with energy applied to the primary indication line circuit from battery IB.

During an on period for example, relays FP1 and 2FP1 at the repeater station are picked up. The relay MF1 is energized or not depending upon the closed or open condition of contact 299 of relay PF2 at the eld station. It will'be assumed that contact 299 of relay PF2 is closed during the first on period. Therefore relay MF1 will be picked up, but just before it is connected into the secondary indication line circuit this line circuit is precharged.

When relay N01 picks up to mark the beginning of the first on period in the control linel relay 2FP1, the indication battery is connected to the secondary indication line circuit through charging resistor CRS1 over a circuit extending from the terminal of battery IB1, resistor CRS1, front contact |42 of relay FP1, back contact MI of relay 2FP1, front contact Itl of relay SA1, front contact |53 of relay SB1 and back contact H59 of relay LV1 to secondary indication line conductor IL1. This connection of battery IB1 to the secondary indication line circuit through resistor CRS1 is effective to apply a charging current to the secondary indication line circuit before the Winding of relay MF1 is inserted vin this line circuit to detect its closed or open condition at the transmitting eld station.

Thefirst on codeV in the secondary indication line circuit in the above description was one during which the secondary indication line circuit was closed because relay PF2 was picked up during the first off period, due to the connection to by way of jumper 282. Therefore, since the transmission of the rst on indication is one which requires the closed condition of the secondary indication line circuit, it will be obvious that it was not necessary to precharge the indication circuit, because the message relay MF1 was supposed to pick up during this on period. However in the event that an on indication is transmitted which requires that this line circuit be open at the transmitting eld station, the application of the charging current to the line circuit just before the message receiving relay is inserted into this line circuit charges the secondary indication line circuit to terminate any flow of current which might be effective to falsely operate the message receiving relay when it is inserted into the circuit and supposed to remain down because of the open condition of the indication circuit.

A similar condition exists during the transmission of off indications, for example the sec-

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