US2528073A - Traffic direction control apparatus for use in centralized traffic control systems for single-track railroads - Google Patents

Description

4 Sheets-Sheet F. T. PASCOE ET AL FOR SINGLE TRACK RAILROADS IN CENTRALIZED TRAFFIC CONTROL SYSTEMS TRAFFIC DIRECTION CONTROL APPARATUS FOR USE MN ,wwkkm I m g w Em MEN Oct. 31, 1950 Filed Ma 10, 1945 E RR INVENTORS Frank 7? Pascoe and BYAPbuP Jronze THEIR ATTORNEY" Oct. 31, 1950 F. 'r. PASCOE ETAL TRAFFIC DIRECTION CONTROL APPARATUS FOR USE IN CENTRALIZED TRAFFIC CONTROL SYSTEMS FOR SINGLE mcx RAILROADS 4 Sheets-Sheet 2 Filed May 10, 1945 R RTW RNSY w b EG E HEM EN 5 b 8 m Y m p E m2 M mm. 0 ww W m w 72 m 5 m 2 PB F 1% Oct. 31, 1950 F. T. PASCOE EI'AL 2,528,073

TRAFFIC DIRECTION CONTROL APPARATUS FOR USE IN CENTRALIZED TRAFFIC CONTROL SYSTEMS FOR SINGLE TRACK RAILROADS Filed May 10, 1945 4 Sheets-Sheet 4 FEE 4Z5 0 2% aw 0 %ZEHK G 1:25 114 15 J I]? aim [WE/1? ATTORNEY Patented Oct. 31, 1950 TRAFFIC DIRECTION CUNTROL APPARATUS FOR. USE IN CENTRALIZED TRAFFIC CON- TROL SYSTEMS FOR SINGLE-TRACK RAILROADS Frank T. Pascoe, Carnegie, and Arthur L. Jerome, Edgewood, Pa., assignors to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application May 10, 1945, Serial No. 592,947

25 Claims.

1 Our invention relates to railway trafiic controlling apparatus and particularly to improved circuits for the control of the direction of trafiic movement, for use in Centralized Traiiic Control machines for remote control of traffic in track stretches in which traffic may move in either direction.

In Fig. 1 of application for Letters Patent of the United States, Serial No. 501,254 of H. S. Young, filed September 4, 1943, now Patent No. 2,420,579, granted May 13, 1947, there are shown interlocked circuits at the control ofiice governed by the control levers for the signals which govern train movements into the opposite ends of a track stretch so as to prevent interference with train movements in the event of improper manipulation of these levers and to prevent the reversal of the direction of traffic except when the single track stretch is unoccupied and the signals governing entrance of tramc into the stretch are at stop.

An object of our invention is to provide an improved system of the type. described which is arranged so that the interlocked circuits in the oflice are governed to prevent a change in the designated trafiic direction in a stretch as soon as a control code is transmitted to clear the signal at either end of the stretch.

Another object of our invention is to provide improved traiiic locking circuits for C. T. C. ma-

chines which are arranged to eliminate the un locked interval in existing circuits between transmission of a signal clearing control code and receipt of an indication code which results in locking of the traific direction designating means in the C. T. C. machine.

A further object of the invention is to provide improved equipment of the type described which is arranged so that, after a signal clear control code has been transmitted and the trafiic direction designating means has been locked, the operator can regain control of the traiiic direction designating means only after it has been established that it is proper to permit a change in the designated traffic direction.

Anoth r object of the invention is to provide an improved system of the type described which incorporates locking means which looks the traiiic direction designating means as soon as a signal clear control code is transmitted and which releases the trafiic direction designating means when a signal clear indication code is received, or after a signal stop control code has been transmitted and an indi ation code is thereafter received from the field station through which the signal is controlled.

A further object of the invention is to provide locking means of the type described which becomes efiective as soon as a signal clearin control code is transmitted, and which is automatically released when other locking means becomes eiTective.

Another object of the invention is to provide in a system of the type described trafiic locking means in the C. T. C. machine which becomes effective as soon as a control code is transmitted to clear a signal governing entrance of trafiic into a stretch, and which thereafter remains eifective until it is certain that conditions in the stretch are such that it is proper for the established traiiic direction to be disturbed.

A. further object of the invention is to provide improved trafiic locking means of the type described which employs in the C. T. C. machin a traffic locking relay which is operated when a signal clearing control code is transmitted to a field station, and which provides means in the C. T. C. machine for operating the signal indication relay when a stop signal control code is thereafter transmitted so that the locking may be released upon receipt of an indication code from th field station.

Another object of the invention is to provide improved means of the type described which is arranged so that operation of the indication lamps governed by the signal indication relay will not be altered by use of the signal indication relay in conjunction with the traflic locking means.

A further object of the invention is to provide improved trafiic locking means of the type described which is arranged to insure that the looking is effected before a signal clear control code is transmitted and so that, if the locking is thereafter released, it is certain that the prescribed operations have been performed.

In practicing our invention we provide in the C. T. C. machine a traflic locking relay which is picked up upon transmission of a control code to clear a signal governing entrance of tramc into a stretch through which traflic may move in either direction. When this locking relay is picked up, it interrupts the circuit of the traffic designating relay to insure that it maintains trafiic in the direction designated at the time the signal control code was transmitted. The indication codes received from the field following the signal clear control code release the locking relay but cause other relays to lock the traflic direction designating relay so that control of the traffic direction designating means is thereafter subject to traffic conditions in the stretch. If an indication code is not received from the field which releases the locking relay, it may be released by sending a signal stop control cod and thereafter receiving an indication code from the field which re leases the locking relay but also includes elements which will result in locking of the trafiic direction designating relay unless it is proper for the operator to have control of the traits direction designating relay. In one form of the invention a special auxiliary relay is employed in releasing the locking relay following a signal stop control code, and in another form of the invention the signal indication relay is employed for this purpose.

We shall describe two forms of railway traffic controlling apparatus embodying our invention and shall then point out the novel features thereof in claims.

In the drawings,

Figs. 1A and 1B are a diagram of a stretch of single track railway equipped with wayside signaling apparatus governed by a centralized traific control system,

Fig. 2 is a diagram of the circuits in the C. T. C. machine at the control office and controlling the wayside equipment shown in Figs. 1A and 1B, and

Fig. 3 is a fragmentary diagram showing a modified arrangement of circuits which may be employed in the C. T. C. machine.

Referring to Figs. 1A and 1B of the drawings, there is shown therein a stretch of single track railway extending, between two passing sidings, the rails of which are divided by insulated joints to form a series of track sections IT to BT, in-

elusive, each section being provided with a conventional track circuit having a track relay for detecting the presence of a train in the section. The stretch is provided with Wayside signal apparatus comprising a system of cascade-connected reversible line circuits controlled by the track relays and by two manually controllable trafilc relays EWFSR and GEFSR of the polar stick type at the ends of the stretch. Each line circuit as shown is energized at its left hand end,

for the control of the head block signal 41A or ELB according to the position of switch 3W, and of the intermediate signals 5L and GL, for authorizing traific to move in the right to left direction through the stretch. The system may be set up for authorizing tranic to move in the other direction by reversing the trafdc relays ZWFSR and lEFSR, in which cas each line circuit is energized at its right hand end, for the control of the head block signal ERA or ZRB according to the position of switch lW, and of the intermediate signals ER and ER. In this application only the portions of the wayside apparatus essential to the understanding of this invention have been shown, these being arranged substantially as shown in the above identified application of H. S. Young. The remainder of the equipment, com prising the apparatus for authorizing trafiic to move through the passing track area, may likewise be arranged as shown in this Young application.

As shown the wayside signals are of the wellknown Searchlight type and may be constructed as shown in Letters Patent of the United States No. 1,864,224, issued June 21, 1932, to W. B. Wells.

Each signal comprises a lamp and awinding which when energized operates a circuit controller and a spectacle frame for placing difierent colored roundels in front of the lamp. The lamps for the head block signals are connected directly to the terminals B and C of a local source of current so that they are lighted continuously, while those for the intermediate signals are lighted upon the approach of a train, by the release of an approach relay LAR or BAR, the winding of which is included in th line circuit system. If energized by current of normal polarity, as illustrated by signal 6L, front contact G closes, and the signal is conditioned to display a green or proceed aspect when its lamp is lighted. Each signal energized by current or" reverse polarity, as illustrated by signal 5L, closes a front contact Y, and its lamp if lighted displays a yellow or caution aspect. Each deenergized signal closes its back contacts G and Y and displays a red or stop indication when its lamp is lighted. The front contacts G and Y of each signal control a repeating relay LPC or RPC which governs the line circuit for the next signal in the rear, while the back contacts G and Y are checking contacts which generally are included in circuits governing opposing signals.

At intermediate locations, the signals are controlled directly over the line circuits, and directional stick relays are provided for supplying current of reverse polarity to the signal for the section in the rear of an occupied section, in the established direction, in accordance with the usual practice.

At the end locations, th signals are governed in accordance with trafiic conditions in the stretch by a polarized line relay ZRHD and ALHD which is included in the line circuit at the entrance end by the reversal of the associated traffic relay, and the signals are also governed by a manually governed signal control relay ZRI-ISR or ELHSP', and by contacts which reflect the position of the adjacent track switch.

For an understanding of the present invention it may be assumed that the track switches IW and 3W remain in their normal position, in which case signal ZRA or 4LA is energized normal or reverse, when its signal control relay is reversed, in accordance with the polarity of the current supplied to its line relay, while signals 2R3 and LB remain deenergized.

The equipment at the left-hand or west end of the stretch includes a C. T. C. system field station unit designated station l2, and the equipment at the right-hand or east end of the stretch includes a C. T. C. system field station unit designated station 3- 3.

The field stations are connected with the ofiice over a pair of line wires, not shown, by a code communication system which may be of the type shown in Letters Patent of the United States No. 2,229,249, issued January 21, 1941, to L. V. Lewis, or in application for Letters Patent of the United States, Serial No. 496,907, filed July 31, 1943, by A. P. Jackel, now Patent No. 2,411,375, granted .Nov. 19, 1946, which system is described in Manual 596A of the Union Switch and Signal Company, Swissvale, Pa.

Consideration of the detailed mode of operation of the code communication system is not needed for an understanding of our invention and it is deemed sufficient to point out that a field station is provided at each end of each track stretch to be controlled and that coding units are provided at the office and at each field station and are connected by a pair of line wires, not shown, over which control codes are transmitted at times from the ofiice to a selected field station, and at other times indication codes are transmitted over the same line wires from the .diiferent field stations to the office without interference. Transmission of each code includes the temporary establishment of a plurality of communication channels, such, for example, as

seven, between the oifice and a station to position a group of relays.

Each code includes a distinctive code call by means of which a selector relay l-ZS' or 3-4S at the ofiice, shown in Fig. 2 and a similar relay, not shown, at one station only is energized to efiect temporary establishment of seven communication channels between the office and the station. The different stations have difierent code calls, consequently the selector relays for different stations or panels are not energized at the same time, and the same channels provide communication at different times with all of the stations.

The explanation of this invention requires only three channels employed in the transmis- I sion of control codes and five channels employed in the transmission of indication codes, and in order to simplify the disclosure the other channels and related apparatus have not been shown.

The channels employed in the transmission of control codes are designated 2, 5 and I, and the channels employed in the transmission of indication codes are designated l0, l2, l3, l4 and I5, the numbers employed to designate these channels being the same as are employed to designate the corresponding channels in the above-identified application of H. S. Young.

It is to be understood that the system of our invention is made up of a number of unit portions generally similar to the one shown in the drawings, but as the invention may be fully understood from one such portion, only one has been illustrated in the drawings.

The office and field stations are each provided with a suitable source of direct current, such as a storage battery, not shown, the terminals of which are designated B and C in the drawings.

In most instances in the drawings the relay contacts are located directly under the Winding of the relay, but in some cases in order to simplify the drawings, relay contacts are separated from the relay winding and in these instances the'relay with which the contacts are associated is designated by appropriate reference characters placed above the contacts.

The equipment at each field station includes a starting relay FST, which responds to a change in position of any of the associated indicating relays to provide connection from terminal B of a source of current to the indication channels to effect delivery of indication codes over the line wires during the time that a delivery relay D at the ofiice is energized to thereby position a group of indication relays in accordance with the condition of energization of the indication channels.

The indication relays at the oflice governed from the'field station l2, at the left-hand or west end of the single track stretch, include a track indication relay ITK which controls a lamp in the track diagram of the control machine to indicate the condition of occupancy of the detector section !T, Fig. 1A, containing the track switch IW, the relay ITK being controlled by the track relay ITR for the track section;-

repeats the stop indications of the signals 2RA and ZRB; and a block indication relay ZRBK controlled by the relay ZRBP which in turn is governed by trafiic conditions in the single track stretch.

The relays at the field station 34 at the right-hand end of the single track stretch function in a similar manner to control the relays 3TK, 4LI-IK and ALBK at the oflice.

The block indication lamp BKE in the track diagram of the control machine is governed by the relays ZRBK and 4LBK, one of which indicates the condition of occupancy of a portion of the single track stretch and the other of which indicates the condition of occupancy of the remainder of the single track stretch.

The signal levers ZSIG and 4SIG on the panel of the control machine are the usual three-position levers for the code control of the signal control relays at the field stations at the op posite ends of the stretch. The signal levers ZSIG and 481G are electrically interlocked with respect to the control of train movements into the intervening single track stretch by electroresponsive means comprising a master directional polarized relay 2-4LP, as in the above identified application of H. S. Young and also in his Letters Patent of the United States No. 2,326,991.

Relay 24LP determines the direction for traific movements through the stretch, and is energized whenever a signal lever is reversed with the object of clearing a signal to authorize a train to enter the stretch, provided the indicated tramc conditions are such as to makeit proper to change the trailic direction. Under other conditions, relay 2-4LP, is locked deenergized, and it then prevents interference with traffic if the operator should attempt to reverse the direction, or to clear an opposing signal.

With relay 24LP in its normal position as shown, if lever 4SIG is moved to position L, lamp WFE is lighted to designate the right to left direction, while if lever ZSIG is moved to position R with lever 481G in position N or R, relay 2-4LP reverses, if the locking conditions permit,and then lights lamp EFE to designate the left to right direction. In either case, the pressing of the starting button associated with the operated lever causes the transmission of a control code to the corresponding station 3-4 or |2 to operate the signal control relay for the signal which such lever controls, but only if relay 2--4LP occupies the corresponding normal or reverse position.

In the event the position of relay 26LP is changed, as for example, when relay 2 iLP is reversed by moving lever ZSIG to position R, the control code which reverses the signal control relay also reverses the associated trafiic relay, and the starting button operation which initiates this code causes the transmission of a second control code by which the traffic relay at the opposite end of the stretch is restored to normal, so as to reverse the direction ofenergization of the line circuit system to enable signal 4RA to be cleared.

The clearing of a signal is indicated by the lighting of lamps controlled by the corresponding signal indication relay, the operation of whichin response to the clearing ofthe signal locks relay 24LP deenergized. As the train governed by the signal moves through the stretch its progress is indicated by the lighting of lamps in the track diagram by the track and block indication relays as these are successively energized by indication codes initiated by the train. Relay 2-4LP is maintained deenergized unt-il lever ZSIG is restored to position N or L, lever ASIG to position N or R and all of those indication relays have been released and indicate that the block is vacant and that the head block signals are at stop.

The relay 2-4LP has associated therewith relays 24LPS and 2- 3BKSR which are governed in the manner explained in detail in application for Letters Patent of the United States, Serial No. 567,188, filed December 8, 1944, by F. T. Pascoe and A. L. Jerome, now Patent No. 2,411,387, granted Nov. 19, 1946. Relay 2-4LPS is av normally energized relay the release of which indicates that the position of relay 2'(lLP has been changed, and its purpose is to operate relays 2-4BKSR, 2RBK and ALBK in response to such change. One purpose of relay 2-4BKSR is to store a block clear indication registered 5 by relays ZRBBZ and 4LBK to enable relay 2-4LP to be operated in such manner as toprevent he locking of relay 25LP by these relays and the lighting of the block occupancy indicator BKE while the wayside system is being reversed and is incapable of indicating traokway conditions, in order to enable the operator to restore the original trainc direction, if for any reason its reversal cannot be consumated. Another purpose is to establish circuits for the starting relays governing transmission of control codes to the stations at opposite ends of the stretch so as to insure that control codes will be transmitted to both stations for the operation of the trafiic relays, following a change in the position of relay 2-$LP..

The relay 2-4LP also has associated therewith a traffic locking relay 2%FL and a releasing relay 2-3FLO, which are provided in accordance with the present invention in order to control the relay 23LP under certain conditions not provided for by any of the other relays referred to, as hereinafter explained in detail.

The push-buttons l-2STB and 3-4STB are the starting buttons for operating the usual code starting relays l-2ST and 3-5ST by means of which control code are initiated and the corresponding stations selected. Each starting relay when energized initiates a control code as described in Lewis Patent No. 2,229,249 including a code call for energizing a selector relay l-2S or 3-48 for the same panel. Each selector relay when energized releases the associated starting relay and connects terminal B of a local source of energy to selected ones of the control channels in accordance with the positions of the signal levers and of contacts of the master directional relay 24LP.

The equipment is arranged so that when energy is applied to channel 2 and a control code is transmitted to a field station, the trafiic directional relay ZWFSR or :EEFSR at that station is operated to condition the wayside apparatus to make that end of the stretch an exit or leaving end. Similarly, the equipment is arranged so that when energy is not applied to channel 2 and a control code is transmitted to a field station the traffic direction control relay is operated to co7edition the wayside apparatus to make that end of the stretch an entrance end so that the signal at that point may be controlled by the wayside circuits on operation of the associated signal relay.

The equipment is also arranged so that, when energy is supplied-to the code channel governing a signal control relay, such as, for example, channel 5 or 7, and a control code is transmitted to a field station, the signal control relay at that station, such as relay dLHSR. or ZRHSR,v is operated by the code to render the signal'subject to the control of the wayside circuits. When energy is not supplied to the code channel governing a signal control relay, and a control code is transmitted to a field station, the signal control relay at that station is restored to normal by the code to keep the signal at stop irrespective of the wayside circuits.

The signal levers ZSIG and 481G are of the three-position type and each has a normal center position N, a left-hand position L, and a righthand position R. The levers control contacts which are shown diagrammatically in the'drawings, the contacts which are closed in th'e'lefthand position of the lever being designated L; those which are closed in the right-hand position of the lever being designated R; those which are closedin either the normal or the left-hand position of the lever being designated NL; and those which are closed in either the normal or the righthand position of the lever being designated NR.

The equipment at the oifice includes a relay MP which is energized from terminal 5? of the office coding unit as shown in Manual 506A of The Union Switch and Signal Company with the Signal Company with the result that relay MP is energized when and only when the ofiice coding unit is transmitting a control code. The offioe equipment also includes a relay Mill? which energized from terminal 8 of the coding unit with the result that relay M8? is normally energized but is momentarily deenergized after the eighth step of each control code.

The equipment is shown in the condition which it assumes when the track stretch is vacant, the signals 2R, and 4L are at stop, and the signaling apparatus prepares the stretch for westbound traific. At this time the contacts 29 and 21' of the traific directional relay 2WFSR at the lefthand or west end of the stretch are in their left-hand or normal positions and connect the line wires 23 and 24 over back contacts 25 and 26' of rela ZLAlPC to a source" or energy series with an approach relay ZRAR. Relay ZLAPC is controlled as shown and described in the aboveidentified application of H. S. Young, so that it is energized only when signal ZLA is cleared. The energy supplied to the line wires 23 and 24 feeds over front contacts of track relays tTR, 2TB, and 4TB, over back contacts 2'! and 28 of relay 5RPC, and back contacts 36 and 3dof relay 5RSR to the winding of signal 5L and causes this signal, when lighted, to display its yellow or caution indication. The energy supplied to line wires 23 and 24 through the winding of relay 2RAR keeps contact 33 of the relay" picked up to establish a circuit for relay ZRBP and contact 34 of relay ZRBP is picked up to interrupt the circuit leading to terminal M'of the C. T. C. system field station unit and thus cause indication codes sent to the ofiice to release relay ZRBK.

At this time signals 2RA and 2RB are at stop' so the circuit of relay 2RRGP'is complete and its contact 35 interrupts the supply of energy to terminal of the C. T. C. system field station unit, and as section IT is vacant, contact 36 of relay ITR is picked up and interrupts the supply of energy to terminal 10 of the field station unit.

Accordingly, indication codes sent to the .oflic'e from this station release relays ZRHK and ITK.

As signal 5L is conditioned to display its yellow" indication, energy is supplied over back contact G and front contact Y of the signal to relay SLPC and its contacts are picked up to cause energy of normal polarity to be supplied to line wires 40 and 4| leading to the winding of signal 6L. At this time wire 4| is connected to terminal C of a source over front contact 42 of relay ELPC, and wire 40 is connected over front contact 43 of relay LPC, front contact 45 of relay 4TB, winding of relay ELAR, and back contacts Y and G of signal 5R to terminal B of the source. The energy supplied to signal 6L causes it, when lighted, to display its green or clear indication, while energy is supplied over back contact Y and front contact G of the signal 6L to relay BLPC with the result that its contacts are picked up and cause energy of normal polarity to be supplied to line wires 48 and 49 over a circuit similar to that described above for line wires 48 and 4!. This circuit includes in series therewith the approach relay GLAR.

The energy supplied to line wires 48 and 49 is supplied over contacts 59 and 5! of relay lEFSR in their right-hand or reverse position to a polar relay 4LHD to pick up its neutral contacts and to cause its polar contacts to occupy their lefthand or normal positions so that polar contact 53 and neutral contact 54 provide a circuit for relay 4LBP and contact 56 of relay 4LBP interrupts the supply of energy to terminal l2 of the field station unit and causes indication codes sent to the office to release relay 4LBK.

As shown, the contacts 58 and 59 of the signal control relay 4LHSR are in their left-hand or normal positions and interrupt the circuits for supplying energy to the windings of signals 4LA and 4LB and these signals are both at stop and establish the circuit of relay 4LRGP so that its contact 60 interrupts the supply of energy to terminal l3 of the field station unit. As section 3T is vacant, contact SI of track relay 3TB interrupts the supply of energy to terminal l6 of the field station unit, and indication codes sent to the ofiice from this station release relays 4LI-IK and 3TK.

Referring to Fig. 2, which shows the equipment at the office, the contacts of relay 24LP are in their left-hand or normal position in which they designate west-bound tranic in the stretch shown in Figs. 1A and 1B. In addition, at this time relay 24LPS is energized by current supplied over its stick circuit, and relays 24BKSR, 24FL and 24FLO are released. As the relay 24FL and the indication relays 4LI-IK, ZRHK, 4LBK, 2RBK, 3TK and ITK are all released, energy may be supplied to one or the other of the windings of the relay 24LP on movement of the signal lever ZSIG or 451G to thereby move the contacts of relay 2-4LP if the operator wishes to change the designated traffic direction.

For purposes of illustration it will be assumed that the operator wishes'to clear the signal 4LA to authorize a westbound train to enter the stretch. In order to clear this signal, he moves lever 4SIG to its left-hand position L and presses the starting button 34STB to pick up the starting relay 3-4ST and cause a control code to be sent to field station 34. On this movement of the lever 4SIG, the circuit is completed to supply energy to the lower winding of relay 2-4LP, but as its contacts are already in their left-hand position, the supply of energy to this winding is without effect.

During transmission of the initial or station selection steps of the control code sent to station 34, the selector relay 34S at the office is picked up with the result that energy is supplied over normal polar contact it! of relay 24LP, front contact 7! of relay 34S, back contact 12 of relay 2-4FLO, and a contact of lever 4SIG to terminal 5 of the office coding unit during transmission of the function steps of the control code sent to station 34, and the control code sent to station 34 reverses the contacts of relav 4LI-ISR.

In addition, during operation of the oiilce coding unit to transmit a control code, energy is supplied to terminal 51 and picks up relay MP so that on picking up of relay 34S energy is supplied over front contact '55 of relay MP, contacts l6 and H of relay 24FL, normal polar contact 18 of relay 24LP, front contact of relay 34S, a contact of lever 4SIG, back contact 8! of relay 4LI-IK, back contact 82 of relay 3TK, and back contacts 83 of relay 34D and 84 of relay 2--4FLO in multiple to the lower winding of relay 24FL. The energy supplied to this winding picks up the relay contacts so that contact 85 moves contact 11 out of engagement with contact 76 and connects terminal B of the battery to contact H to provide a stick circuit for relay 24FL and keep its contacts picked up after release of relay MP. In addition, When relay 2-4FL picks up, it contact 88 shunts contact 80 of relay 34S and the contact of lever 4SIG in the pick-up circuit of relay Z4FL and thus keeps relay 2--4FL picked up after release of relay 34S or after lever 481G is moved from its position L.

When relay 24FL picks up, its contact 81 interrupts the circuits of relay 24LP to thereby prevent supply of energy to the windings of this relay and thus prevent movement of the relay contacts to change the designated direction of traffic in the track stretch controlled thereby.

As relay 24FL is picked up as soon as relay 345 picks up, which occurs during the station selection steps and prior to the function steps of the control code, and as relay 24FL when picked up locks relay 24LP to prevent a change in the designated traific direction, there is no possibility that the contacts of relay 24LP can be moved to change the designated trafiic direction aftera control code has been sent to clear a signal. If, for example, after the control code is sent to station 34 to clear the signal 4LA but prior to receipt at the office of the signal clear indication code to pick up relay 4LI-IK, the operator moves lever 4SIG to its center or its righthand position, and also moves lever 2SIG to its right-hand position, energy will not be supplied to the upper winding of relay 24LP since contact 8'! of relay 24FL is picked up and interrupts the circuits of relay 2-4LP. Accordingly, the contacts of relay 24LP are certain to remain in their existing positions and maintain the direction of trafiic which was designated at the time the signal control code was transmitted, in this case, westbound trafiic.

If under the conditions outlined above the contacts of relay 24LP should be moved and a control code should thereafter be sent to station l2 to condition that end of the stretch to be an entrance end, it would cause the wayside equipment to attempt to establish eastbound trafiic and would result in putting to stop the westbound wayside signals with resultant interference with movement of westbound trafiic in the 1 l stretch which had been authorized by clearing of signal ALA.

Since relay 2-4FL, which is being added by this invention, operates to lock the relay 2-4LP as soon as the signal clearing control code is sent, there is no possibility that subsequent movement of the signal control levers will cause movement of the contacts of relay 24LP with resultant interference with the designated trafiic direction.

As explained above, when the signal control code is received at field station 3--4, the contacts 58 and 59 of relay ALI-18R. are reversed to cause energy to be supplied to the Winding of signal iLA over the circuit controlled by neutral and polar contacts of relay iLI-ID and by contacts 90 and 91 which are governed in accordance with the position of switch 3W so as to establish the circuit of signal ALA when and only when the switch i in its normal position As shown, the switch 3W is in its normal position and the polar contacts of relay iLHD are in their normal position so that energy is supplied to the winding of signal @LA to cause itto display its green or clear indication. When signal QLA clears, the circuit of relay ALRGP is interrupted and it releases to cause energy to be supplied over its back contact til to terminal $3 of the field station unit while a contact of relay GLRGP momentarily interrupts the circuit oi the starting relay 34 FST to cause an indication code to be sent to the office to pick up relay iL-HK to show that signal #Lif has cleared.

In addition, when relay ALRGP releases, its contact 115 interrupts the circuit of an approach locking stick relay yiLAS and it releases to interrupt its own stick circuit, while contact H6 of the relay flLAS establishes a circuit to supply energy tcterrninal i3 of the field station unit when contact 59 of relay GLHSR is in its normal position. The relay lLAS, when released, operates in the well-known manner to prevent movement of the switch 3W and to prevent clearing of the signal ARA or 413B, while the relay ALAS may operate as explained in the above-identified application of H. S. Young to control the supply of energyto the terminal, not shown, of the field station unit which controls the indications of signals {ERA and QRB to thereby send to the oflice a distinctive indication when the time looking isin effect.

When relay ALHK picks up, it establishes a stick circuit for itself while its contact 8! interrupts the stick circuit for relay 24FL and its contacts release, but before contact 8'? of relay 1 2 sFL establishes the circuit of relay 24LP, contact of relay 4LHK is picked up to interrupt this circuit and thereby prevent movement of the contacts of relay 2 lLP while a signal governing entrance of traffic into the stretch is displaying a permissive indication.

Under some conditions transmission of indication codes from the field station to the office may be delayed and a train may accept signal 4LA and enter the single track stretch before the signal clear indication code is sent to the oifice. When a westbound train enters section 3T, the track relay ST-R. releases to interrupt the circuit of the slow release repeater relay 3'1? and cause energy to be supplied over back contact 94 of relay 3TH and front contact 95 of relay STP to the lower winding of relay QLHSR during the release period of relay STP and contacts 58 and 5%} of relay @LHSR are moved to their normal position to interrupt the supply of energy to the w nding of s na s jAa this caus t i n to display its stop indication. Also on release of relay its contacts 96 and 97 interrupt the circuit of relay 4LHD and its neutral contacts release to additionally interrupt the circuit of signal When signal the displays its stop indication, the circuit of relay (A LRGP is complete and its contact 68 interrupts one branch of the circuit leading to terminal 13 of the C. T. C. unit.

When relay iLRGP picks up, energy is supplied over its front contact H5 and a back contact of relay 3TR to relay 4LAS and its contacts pick up to establish a stick circuit to keep the relay energized after relay 3TB, picks up, while contact H6 of relay ILAS interrupts the second branch of the circuit leading to terminal 13 of the C. 'I'. C. field station unit, consequently indication codes which follow a control code for clearing signal 4LA do not pick up relay .(lLHK unless transmitted before the train governed by the signal enters section 31.

However, when relay 3TH is released, its contact 5] establishes the circuit for supplyingenergy to terminal in of the field station unit so that indication codes sent to the ofiice pick up relay 3TK. The supply of energy to terminal 10 of the field station unit may be controlled by track relay STR through a stick repeater relay, not shown,

,. which operates as explained in the above-mentioned Manual 506A to maintain the supply of energy to terminal Ii) until an indication code has been sent to the office. This insures that the indication of occupancy of section 3T will be sent to the ofiice even through transmission of the indication code is delayed so that section 3T is vacated before the indication is transmitted.

When the relay SIK at the ofiice picks up, its contact $8 interrupts the circuit of relay 2-4LP, and its contact 82 interrupts the stick circuit for relay 2-4FL and its contacts release. As contact 98 of relay 3TK interrupts the circuit of relay 2,4LP before contact 81 of relay 2 4FL releases, there is no period during which the cir- 1 cuit of relay 2-4LP is established, and therefore no possibility that energy may be supplied to relay 2-4LP to move its contacts and change the designated traific direction during occupancy of the stretch.

From the foregoing it will be seen that inclusion of a contact of the indication relay STK for the detector section at the entrance end of the stretch in the control of relay 2-4FL insures that this'relay will be released upon entrance of a train into the stretch if the relay has not al read been released by receipt of a signal clear indication, and thereby makes certain that the locking of relay 24LP will be released when the stretch is vacated.

On release of relay lLHD at field station 34 its neutral contact "5 1 interrupts the circuit of relay ZLBP and contact 55 of relay 4LBP releases to supply energ to terminal I2 01" the field station unit and cause indication codes sent to the office to pickup relay Z-LBK and cause its contact 93 to interrupt the circuit of relay 2- lLP.

On continued movement of the train through the stretch, the block and detector section indication relays control the circuits of the detector section and block occupancy lamps in the track mode1 on the panel of the control machine, while contacts of these relays interrupt the circuits of relay 24LP to insure that the contacts of this relay remain in their left-hand position and maintain westbound traific. As hereinafter explained,

the circuits of the traffic direction lamps and EFE are controlled in a Somewhat different manner than heretofore.

If desired, the contact 8! of relay 4LI-1K in the pick-up and stick circuits of relay 2--4FL may be omitted, and if this is done, the relay 24FL when picked up remains picked up until released by the relay BTK, or is released in the manner explained below.

If an indication code is sent to the ofiice after a signal clear control code has been transmitted but before the signal has cleared or a train has entered the stretch, contact 83 of relay 34D will pick up momentarily, but at such times this contact is shunted by contact 84 of relay 2-4F'LO so the stick circuit of relay 24FL is not interrupted and relay 2-4FL remains picked up tointerrupt the circuit of relay 2-4LP.

After a control code has been transmitted to clear a signal governing entrance of trains into one end of the stretch and before an indication code has been received in response thereto, the operator may find it advantageous to change the direction of traffic in the stretch and clear the signal governing entrance of trafilc into the stretch at the other end. This equipment is arranged so that after a, signal clear code has been transmitted, the operator can regain control of of the traffic direction designating relay to change the direction of traffic in the stretch only after it has been determined that it is safe for him to do so.

As explained above, when a control code is sent to clear signal 4LA, the relay 24FL is picked up to interrupt the circuits of the relay 2-4LP and thus prevent a change in the designated traffic direction. If the operator now decides to establish eastbound traiiic in the stretch and to clear signal ZRA, he must first move signal lever ASIG to its normal position or to its right-hand position and send a control code to field station 3-4. On this movement of the lever 4SIG the contact in the circuit leading to terminal 5 of the office coding unit is opened to cause the controlcode sent to stations 3-4 to move the contacts of relay lLHSR to their normal positions and thus cause signal iLA to display its stop indication.

When lever 4SIG is in its center or its righthand position, but relay 2-4FL is picked up because a signal clear control code has been transmitted and has not been followed by an indication code which will release the relay 24FL, and a control code is sent to station 34, terminal B of the battery is connected to one terminal of the winding of relay 24FLO over the circuit which includes contacts 85 and ll of relay 2-4FL, normal polar contact 18 of relay 2LP, front contact 80 of relay 34S which is picked up during transmission of a control code to station 34, contact NR of lever 481G, contacts WI and 102 of relay 24FLO, and front contact I03 of relay 24FL.-

As explained in Manual 506A referred to above, the supply of energy to relay M8P is temporarily interrupted during the eighth step of the control code sent to station 3-4 and the contacts of relay MBP release for a short time interval. When relay M8P releases, terminal C of the source is connected over back contact 105 of relay MBP, and contacts I06 and I0! of relay 2-4FLO 1 to a terminal of the winding of relay 24FLO to complete the circuit of the relay. The contacts of relay 24FLO now pick up and contact I08 moves contact I02 out of engagement with contact IOI and connects terminal B of the source over front contact 103 of relay 2--4FL to one:

terminal of the winding of relay 24FLO, and contact I09 moves contact I01 out of engagement with contact I06 and connects terminal C of thesource to the other terminal of the relay winding so that, after picking up of relay M8P, relay 2 lFLO is maintained energized by current supplied over a stick circuit governed by contact [03 of relay 24FL. When relay 2-4FLO picks up, its contact 84 in the circuit of relay, 2.4FL is opened, but energy continues to be supplied to relay 2-4FL over back contact 83 of relay 3-4D so relay 2'4FL remains picked up and its contact 8! interrupts the circuits of relay 2-4LP. Also when relay 2-4FLO picks up, its contact 12 interrupts the circuit leading to terminal 5 of the oflice coding unit to thereby prevent supply of.

energy to this terminal in the event the lever 4SIG is restored to its left-hand position after picking up of relay 2 iFLO but prior to transmission of the step of the control code governed by terminal 5 of the ofiice coding unit. Opening of contact 12 of relay 2-4FLO, therefore, guarantees that the signal control element of the control code sent to station 34 will cause' the contacts of relay dLHSR to be moved to their normal positions to cause signal 4LA to displayits stop indication. As signal 4LA displays its stop indication the circuit of relay 4LRGP is complete and it picks up to interrupt the. branch of the circuit which it controls leading to terminal l3.

of field station 3-4.

The signal stop control code sent to station 3-4 causes this station to transmit an indica- A tion code to the office and when this code is re-' ceived at the oiilce the delivery relay 34D picks up with the result that its contact 83 in the cir-j cuit of relay 24FL is opened. As contact 84 of relay 24FLO is also open, the supply of energy.

to the lower winding of relay 2-4FL over the stick circuit for this winding is interrupted and the relay contacts release to additionally interrupt the relay stick circuit, while contact I03 of relay 2-4F'L interrupts the circuit of relay 2-4FLO and it releases.

After release of relay 2-4-FL as a result of re- 1 at this time may result in picking up of one ormore of the relays 4LHK, 4LBK or STK to interrupt the circuits of relay 2-4LP and thus main-' tain the established direction of traflic in the" single track stretch.

If the signal clea control code previously sent to station 34 resulted in clearing of signal 4LA with consequent release of relay ALRGP, its contact H5 will interrupt the circuit of relay GLASY and it releases to interrupt its own stick cir-' cuit, and contact N6 of relay 4LAS establishes a connection to terminal l3 of the field station unit provided contact 59 of relay iLHSR. is in its" stop as a result of passage of a train, the relay ALRGP picks up but relay 4LAS'remains released so that energy is supplied to the time element device 4TER. After a substantial time interval,

l 5 such "as .6 minutes, the contacts of the device ATER pick up and energy is supplied over its contact -Iil8 torelayALAS to pick up its contacts to interrupt thecircuitof device 4TER and establish a stick circuit for relay lLAS.

When contact vHi5 of relay QLAS is released andcontactfiil of relay ALHSR is in its normal position, the battery is connectedto'terminal 43 of the-field station unit to cause indication codes sent to the office to pick up relayALI-IK even though signal LA isat stop and relay ALRGP is picked up.

Innthis case, as explained in the-above-identified application of H. S. Young, another indication relay ARHK is picked up along with relay 4LHK, which prevents the display of a clearsignal indication by relay 4LHK and provides a distinctive indication of the operation of the device 4TER.

*If signal 'ALA .had .been clearedby the signal clear control code and had been accepted by a train, the signal would have been put-to stop by release of relay .3TR, thereby picking up relay QLRGP, while on picking :up of relay iLRGP a pick-up circuit including its front contact H5 is established for relay ALAS and it picks up to establish a stick circuit for itself and to interrupt the supply of energy to terminal l3 of the field station unit with the result the indication codes subsequently sent to the office do not pick up relay 4LI-IK.

If signal dLA had been put to stop by entrance of a train into the stretch, the relay 3TB will-be released so that its .contact 6! establishes connection to terminal [0 of the field station unit to cause indication codes sent to the ofiice to pick up relay 3TK. Also, if a train enters the stretch, the neutral contacts of relay ALI-ID are released and interrupt the circuit of relay 4LBP so itscontact 56 establishes the circuit to'supply energ to terminal i2 of the field station unit-so that indication codes sent to the office pick up relay dL-BK.

If for any reason the signal ALA did not clear in response to the signalclear control code sent to station .3-4, the relays lLRGP and ALAS remain energized and in this case a train would not have entered the stretch and relays 3TB, 4LHD and GLBP would'have remained energized and indication codes sent to the oiiice would not pick up relay iLBK, 4LI-IKor 3TK.

It will be seen that after the signal stop code has been received at the field station the indication codes thereafter sent to the ofi'lce show conditions at the field station. If-the signal GLA- had been cleared bythe signal clear control code a and was put to stop by the signal stop code so that the time locking is effective, the indication code sent to the oflice will pick :up relay ILHK so that its contact '92 interrupts the circuits of relay 2-4LP and thus prevents a change in the designated traffic direction 'until the time interval determined by device l'I ER expires, at which time relay ALAS picks up and an indication code is sent to the ofiice to release relay 4LHK. This is proper since the signal ALA, when clear, may have caused a west-bound train to advance toward the signal to enter the single track stretch, and, after the signal is put manually to stop, this train may be unable to stop before passing the signal. If a train should overrun the signal and enter the single track stretch, it would release relays 3TB, iLE-ID and 4LBP to cause indication codes to be sent to the ofiice to pick up relays ETK and ALBK and inter- 16 rupt the circuits of relay 2-4LP and thus pre vent a change in the designated traffic direction.

Similarly, if a train had passed signal 4LA and had entered the single track stretch before the signal stop control code was received at station 3-4, the indication codes subsequently sent to the oilice would pick up relaysdLBK and STK to prevent movement of the contacts of relay 2-4LP and thus maintain the established direction of trafiic.

If the signal clear control code sent to station 3-4 had not resulted in clearing of the signal, and if no train has entered the stretch, the indication code sent to the office following the signal stop control code will not pick up either of the relays dLBK, dLHK or 3TK, and as relay 2-4FL is released, the circuits of relay 2--tLP are complete and the operator is free to move its contacts and change the direction of traffic in the single track stretch.

From the foregoing it will be seen that relay 2-4FL operates to lock the traffic direction designating relay 24LP and thus maintain the established traific direction as soon as a control code to clear a signal is transmitted. This eliminates the possibility of interference with trafiic in a stretch in the interval between transmission of a signal clear control code and receipt of an indication code showing that the signal has cleared or has been accepted by a train.

It will also be seen that after a signal clear control code has been transmitted the operator can regain control of relay 2-4LP by first transmitting a signal stop control code and thereafter receiving an indication code to show whether it is proper to permit the established trafiic direction to be disturbed.

If the operator desires to change the direction of trafiic in the single track stretch from westbound to eastbound, he may do so providing the stretch is unoccupied and the signals governing entrance of traffic into the stretch are at stop. Under these conditions the relays controlling the circuits of the windings of relay 24LP are released and if lever dSIG is in its center or its right-hand position, and lever ZSIG is moved to its right-hand position, energy is supplied to the upper winding of relay Z-GLP and its contacts are moved to their right-hand or reverse position. The change inthe position of the contacts of relay 24LP reverses the polarity of the current supplied to relay 2-LPS, causing this relay to release to open its stick circuit and to close back contacts over which relays 2-6BKSR, ZRBK and ALBK pick up as explained in the above-mentioned application Serial No. 567,188 of F. T. Pascoe and A. L. Jerome. If the starting button l-2STB is now pressed, energy is supplied to relays I--2ST and 34ST and they pick up to cause control codes to be sent to field stations !-2 and 34. Relay 24,LPS picks up over the connection now established to terminal 51 of the ofiice coding unit, which as already explained is supplied with energy during the transmission of a control code. At this time contact 10 of relay 2-4LP is in 'its right-hand position so that energy is supplied to terminal 2 of the oflice coding unit during the picked-up period of selector relay 3--4S but'not during the picked-up period of selector relay l2S. Accordingly, the control code sent to the field station 34 at the east end of the stretch moves the contacts of relay 4EFSR to their normal po sitions to disconnect line wires t8 and 49 from relay 4LHD and connect them to a source of energy in series with relay dLAR, thereby changing the east end of the stretch from an entrance to an exit end. Similarly, the control code sent to field station l'2 at the west end of the stretch moves the contacts of relay ZWFSR, to their reverse position to disconnect line wires 23 and 24 from the source of energy and connect them to relay 2RHD and thus convert the west end of the stretch from an exit to an entrance end.

Referring to Fig. 2, as contact 70 of relay 24LP is in its right-hand position, and assuming lever ZSIG is in its right-hand position, energy is supplied to terminal 7 of the office coding unit during the picked-up period of relay |2S and the control code sent to field station l-Z reverses the contacts of relay ZRHSR to cause signal 2RA or ZRB to clear when the neu- 1 east end of the stretch to clear signal BR and thus pick up rela GRPC to supply energy to line wires and 4| to clear signal 5B and pick up relay ERPC to supply energy to line wires 23 and 24 to energize relay ZRHD and cause one or the other of the signals ZRA or ZRB to display a permissive indication. I

Referring again to Fig. 2 it will be seen that when the signal clear control code is sent to station l'2, energy is supplied to the upper winding of relay 2-4FL over the circuit including front contact 15 of relay MP, contacts 15 and ll of relay 2-4FL, reverse polar contact 78 of relay 24LP, front contact H2 of relay l-2S, contact R of lever ZSIG, back contact H3 of relay ZRHK, back contact H4 of relay ITK, and back contact H5 of relay I2D and back contact H6 of relay 24FLO in parallel. When relay 24FL picks up, its contacts 85 and Ti provide a stick circuit for the relay, while its contact I213 establishes a path shunting the contact H2 of relay !-2S and the contactR of lever ZSIG. As relay 2-4FL is picked up, its contact 8'! interrupts the circuits of relay 2-4LP to insure that eastbound trafiic will be maintained until, as explained above in connection with westbound trafiic, it is certain that it is proper to change the direction of trafiic in the stretch. The operation of the equipment following transmission of a control code to clear a signal 2R is similar to its operation following transmission of a control code to clear a signal 4L and a detailed operation of the equipment at such times is unnecessary.

The trafiic direction indication lamps WFE and EFE are governed by contact I25 of relay 2-4LP so that one or the other of these lamps may be lighted depending on the position of contact I25. The circuits of the lamps WFE and EFE are also controlled by the signal levers and by the indication relays so as to be lighted when and onl when it is desirable for the operator to know the direction of trafiic established or to be established in the stretch with which the lamps are associated.

When, for example, neither of the levers ZSIG and ASIG is in a position to clear a signal governing entrance of trafiic into the stretch, neither of the signals 2R and AL is displaying a permissive indication, the relay 2--4FL is released showing that no control code has been transmitted to clear signal 4L or 2R, and when, in addition, the entire stretch is unoccupied, there is no reason for the lamp WFE or EFE to be lighted and having these lamps dark at such times makes the other indication lamps on the control panel more effective since the operator can devote his entire attention to the lamps, lighting of which has some significance.

As soon as a signal lever is moved to a position to clear a signal leading into the stretch it is desirable to indicate to the operator the direction of trafiic in the stretch, and to thereafter maintain this indication until conditions I are such that the indication is no longer required. The circuit of lamp WFE or EFE- is established as soon as a signal lever is moved to a signal clearing position, is maintained by relay 24FL after a signal clearing control code is transmitted, and is thereafter maintained by the signal clear indication relay or by the indication relays governed by occupancy of the stretch. When the stretch is vacated and neither of the signal levers is in a position to clear a signal leading into the stretch, the circuit of lamps WFE and EFE is interrupted and these lamps are extinguished.

A back contact of relay 24BKSR is included in the circuits governed by the block indication relays ALBK and 2RBK for supplying energy to the lamps WFE and EFE. As explained in our application Serial No. 567,188, the relay 2-4- BKSR, and the relays 2RBK and ALBK are picked up on a change in the position of the contacts of relay 24LP and relay 2--4BKSR, remains picked up until relays 2RBK and lLBK are released by indication codes transmitted from the field stations showing that trafiic has been established in the new direction, or until one of the detector section indication relays ITK or 3TK is picked up to show that a train has entered the stretch. Inclusion of the back contact of relay 2--4BKSR in. the circuits governed by relays QRBK and 4LBK for lighting the lamps WFn. and EFE prevents lighting of these lamps by energy supplied over the contacts of relays ZRBK and 4LBK at times when these relays are picked up incident to movement of the contacts of relay 24LP and not because of occupancy of the stretch. At such times one of these lamps may. be lighted by energy supplied over another circuit, as, for example, over a contact of lever 2SIG or 4SIG or over the front contact of relay 24FL. However, the lamps WFE and EFE will not be lighted if no such other circuit is established following a movement of the contacts of relay 2-4LP, as might be the case if lever .2SIG is moved to its position R or lever 481G is moved to its position L, thereby producing movement of the contacts of relay 2--4LP, and if the lever is thereafter moved from this position before a control code is sent.

In the machine circuits shown in Fig. 2 of the drawings a special relay 2-4FLO is provided to release relay 24FL upon receipt of an indication code from a field station subsequent to transmission of a signal stop control code to that station. It is possible to employ the signal indication relays for this purpose, thereby eliminating the need for the relay 2-4FLO, and Fig. 3 is a fragmentary diagram showing this modification. The equipment is shown in the condition which it assumes when relay 2--4LP designates westbound trafiic, the signals 4L are at stop, and a signal clear control code has not been transmitted so that relay 24FL is released,

If the operator wishes to clear signal 4LA, he moves lever 4SIG to the left and presses the starting button for station 3-4 to cause a control code to be sent to that station. When selector relay 34S picks up, energy is supplied to the lower winding of relay 24FL over a circuit identical with that traced in detail in connection with Fig. 2 except that contact 83A of relay ALI-1K is substituted for contact 83 of relay 24FLO. As explained in connection with Fig. 2, when relay 2-4FL picks up, it establishes a stick circuit for itself and a contact of relay 24FL interrupts the circuits of relay 2-flLP to insure that the contacts of relay 2- 3LP remain in their left-hand positions and maintain westbound traiiic in the stretch. The stick circuit for relay 2-4FL established at this time includes its own front contact 88 and differs from the stick circuit shown in Fig. 2 in that contact 88 shunts the contact iii of relay QLHK in the relay pick-up circuit as well as contact 88 of relay 3- 38 and contact L of lever 4SIG.

When relay Z-AFL picks up, its contact I25 establishes the circuit including back contact [2? of relay iLl-IK, front contact ll of relay 3-451, and contact L of lever GSIG for supplying energy to terminal 5 of the ofiice coding unit to cause the control code sent to station 35 to include a signal clearing element. If a signal clear control code is sent while relay ELHK is picked up and relay 2-4FL is released, the relay 2-4FL remains released as its pick-up circuit is interrupted by contact 8! of relay ALHK, and, as relay 24FL remains released, its contact i3l maintains the circuit of lamp ALE and it remains g,-

lightedand contact i26 of relay 2-4FL and contact I27 of relay iL HK'establish the circuit to terminal 5 of the ofiice coding unit.

When signal 4LA clears in response to the control code, an indication code is sent to the office to pick up relay lLHK. At the time this inclication code is registered at the oihce the delivery relay 34D picks up with the result that its contact 8 1 in the stick circuit of relay 24FLis open, and when relay ALHK picks up so that its contact 83A in the stick circuit of relay 2-4FL is also open, the stick circuit for relay 2- iF-L is interrupted and the relay contacts release to additionally interrupt the relay stick'circuit. The relay 34D is picked up for only a short time, but this period is long enough to insure release of relay 24FL, while on release of reiay 34D the relay ALI-1K is maintained picked up by a stick circuit in the usual manner.

When relay GLHK picks up, a contact of the relay interrupts the circuits of relay 2- 413? to insure that it maintains the established trailic direction, and relay QLHK is picked up and relay 2-4FL is released, energy is supplied over front contact l3i3 of relay 4LHK and back contact iii! of relay 2- iFL to lamp LE above lever 4S IG 'and'this lamp is lighted to indicate to the operator that signal tLis displaying a permissive indication. Also on :pickihg'up of relay 4LH-K and' release of relay 2'4FL the circuit leading to terminal 5 of the ofiice coding unit is maintained so that as long as lever ASIG remains in its position L control codes transmitted to station 3 4 will include a signal clear element and will maintain the display of a permissive indication by one of the signals 4L;

If a westbound train accepts signal 512A and enters the stretch so that signal 411A isput to stop, an indication code will be sent to the office to release relay ALHK, but to also pick up other indication relays, asfexplaihedin connection with Fig. 2 and thus lock relay 2'4LP. Oil-release of relay iLI-IK its contact ten-interrupt the cir-' cuit of lamp ALE, "it's contacts :8] and 83A establish the pick-up circuit for relay 2-'' il 1i, andits contact I2? interrupts the 'circuit leading to terminal -5 of the office coding unit to prevent transmission of signal clear control codes unless relay 2-4FL is picked up. On continued movement of the train through the stretch, the equipment operates substantially as explained in connection with Fig. 2.

The modification shown in Fig. 3 is arranged so that, after a signal clear control code has been transmitted to a field station, the operator can regain control of relay 24LP by first sending a signal stop control code to the station and thereafter receiving an indication code showing that conditions are proper to permit him to have control of relay 2--4LP.

As explained above, when the signal clear control code is sent to station 34, the relay 2-4FL is picked up and establishes a stick circuit for itself. If the operator now decides to I convert the stretch from westbound to eastbound traffic, he moves lever LiSIG to its normal or to its right-hand position and presses the starting button 34STB to cause a control code to be sent to station 3- As explained in connection with Fig, 2, the relay MBP releases momentarily on the eighth step of the control code sent to station 34, at which time contact of relay 34S is picked up. Accordingly, when relay MHP releases, energy i supplied to the upper winding of relay cLHK over a circuit, a portion of which is common to the stick circuit for the lower winding of relay 2-4FL. The circuit for supplying energy to rela ALHK includes contacts 85 and H of relay 24FL, contact 18 of relay 24LP, contact 80 of relay 34S, contact NR of lever llSIG, winding of relay lLHK, front contact 03 of relay 2-4FL, and back contact N5 of relay M8P. The energy supplied to relay iLI-IK picks up the relay contacts with the result that contact I32 of relay 4LHK establishes the relay stick circuit which includes back contact I33 of relay -3-tD and front contact I34 of relay 24FL in multiple.

On pickingv up of relay iLHK its contact 8| is opened but is bridged by contact 88 of relay 24FL,and contact 83A of relay ALHK is opened but is bridged by contact 84* of relay 3-4D since operation of the office coding unit is such that relay 3-4D is certain to be released at the time relay ALHK is picked up by energy supplied to its upper winding over the circuit governed by relay M8P. Accordingly, on picking up of relay iLHK at this time the stick circuit for relay 2-4FL is maintained and relay 2-AFL remains picked up. As relays 2-4FL and HLHK are both picked up their contacts 26 and i2? interrupt the circuit leading to terminal 5 of the office coding unit to insure that the control code sent to station 34 includes the signal stop element even if lever ASIG should be moved to its position L.

As relay 24FL is picked up its contact 13! interrupts the circuit of lamp ALE to prevent lighting of this lamp even though relay tLHK is picked up. This is proper since picking up of relay GLHK at this time is not the result of a signal clear indication code received from the field.

As relays 2-4FL and lLHK are both picked up, the circuits of relay 2-4LP are interrupted.

211 as will be clear from Fig. 2, and the relay 24LP is certain to maintain westbound traific in the stretch.

The control code sent to station 3-4 causes that station to send an indication code to the office, and, when this indication code is registered at the ofiice, relay 34D picks up with the result that its contact 84 interrupts the stick circuit for relay 24FL and relay 24FL releases. When relay 3-4D picks up, its contact I33 interrupts thestick circuit for relay 4LHK 1 and connects relay lLI-IK to terminal l3 of the ofiice coding unit. If at this time energy is not supplied to terminal l3, the relay 4LHK will be held picked up by energy supplied over front contact I34 of relay 24FL until relay 24FL releases, whereupon relay 4LI-IK releases. The stick circuit for relay 4LHK provided by front contact I34 of relay 2,4FL insures that relay 'ALHK will remain picked up and interrupt the stick circuit for relay 2-4FL-until this circuit is interrupted by release of relay 2-4FL and thereby makes release of relay 24FL certain at these times.

If at the time the indication code is'received energy is supplied to terminal [3, as may be the case when the time looking is in efiect, the relay lLHK will remain picked up after release .of relay 2-4FL. If at the time the indication code is received a train has entered the stretch, the detector section and block indication relays 3TK and 4LBK will be picked up, as explained in connection with Fig. 2.

In any event the indication code received following the signal stop control code will release 5 relay 2-4FL and establish the circuits of relay 24LP unlessthese circuits are interrupted by one-or moreof the other indication relays.

As pointed out above, when a signal stop control code is transmitted following a signal clear control code but prior to receipt of the signal clear indication, the relay 24FL remains picked ,up and the'relay lLHK becomes picked up with .the result that the lamp 411E is not lighted. If

the signal clear indication is received from the field, the relay ALHK will be picked up and the when relay 2--4LP designates eastbound traffic in the stretch and a control code is transmitted to. clear one of the signals 2H. and a detailed explanation of the operation of the equipment at such times is unnecessary.

Although we have herein illustrated and described two forms of railway traflic controlling apparatus embodying our invention, it is understood that various. changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of our invention.

Having thus described our invention, what we claim is:

1. In direction selecting means for a stretch of railway track equipped with a signaling system governed jointly by traffic direction relays at opposite ends of the stretch so that at times the stretch is conditioned for traffic movements in 22 one direction and at other times for traific move= ments in the opposite direction and having a signal at each end for governing traffic movements into the stretch and a signal control relay for each signal for manually governing the clearing thereof in accordance with the condition of said signaling system, together with a code type remote control system for transmitting control codes for controlling the signal control and traffic direction relays from a central oflice and for transmitting indication codes for indicating traflic conditions at said ofiice, in combination, electroresponsive means at said o ifice for desi nating the direction for trafiic movements and for controlling the transmission of codes by said remotecontrol system by which said trafiic direction relays are operated to establish the'corresponding direction for traffic movements in said stretch, an auxiliary relay at the ofiice, means for operating'said auxiliary relay in response to the transmission of a control code for clearing a signal by operation of its signal control relay, an indication relay at said office for each of said signals, each signal indication relay being operated when an indication is received that the associated signal is clear and being re stored to its normal position when an indication is received that the associated signal is at stop,

means responsive to the operation of a signal indication relay by an indication code transmitted when a signal is clear for restoring said auxiliary relay to its normal position, and looking means at said office comprising normally closed contacts of said auxiliary relay and said indication relays in a circuit for controlling said electroresponsive means, the opening of such contacts being efiective to maintain the designated trafiic direction by preventing the energization of said electroresponsive means when said auxiliary relay occupies its operated position or either of said signal indication relays is in its operated position.

2. In direction selecting means for a stretch of railway track equipped with a signaling system governed jointly by traffic direction relays at opposite ends of the stretch so that at times the stretch is conditioned for traliic movements in one direction and at other times for traffic movements in the opposite direction and having a signal at each end for governing trafiic movements into the stretch and a signal control relay for each signal for manually governing the clearing thereof in accordance with the condition of said signaling system, together with a code type remote control system for transmitting control codes for controlling the signal control and traffic direction relays from a central office and for transmitting indication codes for indicatin traffic conditions at said office, in combination, electroresponsive means at said oflice 'for designating the direction for traflic movements and for controlling the transmission of codes by said remote control system by which said trafnc direction relays are operated to establish the correspondingdirection for trafiic movements in said stretch, an auxiliary relay at the ofiice, means foroperating said auxiliary relay in response to the transmission of a control indication is received that the associated signal is at stop, means for restoring-said auxiliary relay to its normal position in response to the operation of a signal indication relay by an indication code transmitted when a signal is clear, occupancy indication means at said ofiice which is operated when an indication is received that said stretch is occupied and is restored to its normal position when an indication is received that said stretch is unoccupied, and locking means at said control oifice comprising normally closed contacts controlled by said auxiliary relay, said signal indication relays and said occupancy indication means in a circuit -for controlling said electroresponsive means, the opening of such contacts being effective to maintain the designated trafiic direction by preventing the energization of said electroresponsive means when said auxiliary relay, said occupancy indication means, or either of said signal indication relays occupies its operated position.

3, In direction selecting'means for a stretch of railway track equipped'with a signaling system governed jointly by trafiic direction relays at opposite ends of the stretch'so that at times the stretch is conditioned for traffic movements in traffic direction relays from a central office and :3:'

for transmitting indication codes for indicating traffic conditions at said oiiice, in combination, electroresponsive means at said office for designating the direction for traffic movements and for controlling the transmission of codes by said 4.:

means for restoring said auxiliary relay to its normal position in response to an indication code transmitted when a train enters the stretch,

occupancy indication means at said ofiice'which is operated when an indication is received that said stretch is occupied and is'restored to its normal'position when an indication is received that said stretch is unoccupied, and locking means at said control :ofiice'comprising normally closed contacts controlled by said auxiliary relay and said occupancy indication means in a circuit for controlling said electroresponsive.means, the opening of such contacts being effective tomaintain the designated traflic direction by preventing the energization of said electroresponsive -means when said auxiliary'relay or said occupancy indication means occupies its operatedposition.

4. In direction selecting'm'eans for a' stretch of railway track equipped with asignaling system governed 'jointly by traffic direction relays at opposite ends of "the stretch so that "at times the stretch is conditioned for 'traflic movements in one direction and at other times for trafiic movements in the opposite direction and having a signal at each end for governing trailic movements into the stretch and a signal control relay for each-signal for manuallygoverning the clearing thereof in accordance with the condition of 24 said signaling system, together with a code type remote system for transmitting control codes for controlling the signal control and tralfic direction relays from a central office and for transmitting indication-codes for indicating traffic conditions at said office, in combination, electroresponsive means at said ofiice for designating the direction for traffic movements and for controlling-the transmission of codes by said remote control system by which said trafiic direction relays are operated to establish the corresponding direction for traffic movements in said stretch, a first auxiliary relay at the oflice, means for operating said first auxiliary relay in response to the transmission of a control code for clearing asignalby operation of its signalcontrol relay, a second auxiliary relay, means effective only when said first auxiliary relay occupies its operated position for operating said second auxiliary relay in-response to the transmission of a control code for putting a signal to stop by restoring its'signal control relay to normal, a signal indication relay for each signal, means responsive to the indication code transmitted'when a signal is clear for operating the corresponding signal indication relay, means controlled by each signal indication-relay for restoring said first auxiliary relay to its normal position when such indication relay is operated, means controlled by said second auxiliary relay for rendering any indication code transmitted when said second auxiliary relay is in its operated position effective to restore said first and second auxiliary relays to their normal positions, and locking means at saidofiice comprising a normally closed contact of said first auxiliary relay in a circuit for controlling said electroresponsive means, the opening of such contact being effective to maintain the designated traffic direction by preventing the energization of said electror-esponsive means when said first auxiliary relay occupies its operated position.

5. In direction selecting means for a stretch of railway track equipped with a signaling system governed jointly by traffic direction relays at opposite ends of the stretch so that at times the stretch is conditioned for trafiic movements in one direction and at other times for traffic movements in the opposite direction and having a signal at each end for governing traflic movements into the stretch and asignal control relay for each signal for manually governing the clearing thereof in accordance with the condition of said signaling system, together with a code type remote control system for transmitting control codesfor controlling the signal control and traific direction relays from a central office and for 'for operating said first auxiliary relay in response to the transmission of a control-codeforclearing a signal by operation of its signal control-relay, a second auxiliary relay, means effective only when said first auxiliary relay occupies its operated position for operating said second auxiliary relay in response to the'transmission of a control code for putting a signal to stop by restoring its signal control relay to normal, a track in 25 dication relay for each end of the stretch, means responsive to the indication code transmitted when a train enters the stretch at either end for operating the corresponding track indication relay, means controlled by each track indication relay for restoring said first auxiliary relay to its normal position when such indication relay is operated, means responsive to an indication code transmitted when said second auxiliary relay is in its operated position for restoring said first and second auxiliary relays to their normal positions irrespective of the condition indicated by such code, occupancy indication means at said office which is operated when an indication is received that saidstretch is occupied and is restored to its normal position when an indication is received that said stretch is unoccupied,and.

locking means at said oflic'e'comprising normally closed contacts controlled by said first auxiliary relay and said occupancy indication means in a circuit for controlling said electroresponsive means, the opening of such contacts being effective to maintain the designated traflic direction by preventing the energization of said electroresponsive means when said first auxiliary relay or said occupancy indication means occupies its operated position.

6. In direction selecting means for a stretch of railway track equipped with a signaling system governed jointly by traffic direction relays at opposite ends of the stretch so that at times the stretch is conditioned for trafiic movements in one direction and at other times for trafiic movements in the opposite direction and having a signal at each end for governing traffic movements into the stretch and a signal control relay for each signal for manually governing the clearing thereof in accordance with the condition of said Signaling system, together with a code type remote control system for transmitting control codes for controlling the signal control and traffic direction relays from a central ofiice and for transmitting indication codes for indicating traffic conditions at said ofiice, in combination, electroresponsive means at said ofiice for designating the direction for trafiic movements and for controlling the transmission of codes by said remote control system by which said trailic direction relays are operated to establish the corresponding direction for trafiic movements in. said an indication relay at said office for each of said signals, each signal indication relay being operated when an indication is received that the aslays is in its operated position for restoring said auxiliary relay to its normal position, and looking means at said ofiice comprising normally closed contacts of said auxiliary relay and of said indication relays in a circuit for controlling said electrorespqnsive mea l fi p n 0f 511,611,0011- 26 tacts being effective to maintain the designated trafiic direction by preventing the energization of said electroresponsive means when saidauxiliary relay or either of said signal indication relays occupies its operated position.

'7. In direction selecting means for a stretch of railway track equipped with a signaling system governed jointly by traffic direction relays at opposite ends of the stretch so that at times the stretch is conditioned for trafiic movements in one direction and at other times for trafiic movements in the opposite direction and having a signal at each end for governing traffic movements into the stretch and a signal control relay for each signal for manually governing the clearing thereof in accordancewith the condition of said signaling system, together with a code type remote control system for transmitting control codes for controlling thev signal control and traffic direction relays from a central ofiice and for transmitting indication codes for indicating traffic conditions at said office, in combination, electroresponsive means at said ofiice for designating the direction for traffic movements and for con-, trolling the transmission of codes by said remote;

indication is received that the associated signal is clear and being restored to its normal position when an indication is received that the associated signal is at stop, means at the office efiec-.

tive when said auxiliary relay is in its operated position and a control code is transmitted for putting a signal to stop by restoring its signal control relay to normal for, causing the signal indicatiomrelay for such signal to assume its operated position concurrently with the transmission of such control code, means responsive to the indication code transmitted when a train enters said signal indicationrelays is in its operated position for restoring said auxiliary relay to its normal position, and locking means at said ofiice comprising normally closed contacts of said auxiliary relay and of said signal indication relays in a circuit for controlling said electroresponsive means, the opening of such contacts being effective to maintainthedesignated trafific direction by preventing the energization of said electroresponsive means when said auxiliary relay or either of said signal indication relays occupies its operated. position.

8. In direction selecting means for a stretch of railway track equipped with a signaling sys tem governed jointly by trafiic direction relays at opposite ends of thestretch so that at-times the'stretch is conditioned for trafiic movements in one direction and at other times for traffic movements in the opposite direction and having a signal at each end for governing traffic movements into the'stretch and a signal control re' 7 lay for each signal for manually governing the clearing thereof in accordance with the condition of said signaling system, together with a code type remote control system for transmitting control codes for controlling the signal cone 27 trol and trafiic direction relays from a central oilice and for transmitting indication codes for indicating trafiic conditions at said oflice, in combination, a signal control lever at the oilice for each of said signals, each of said levers oeing movable between a clear and a stop position, electroresponsive means at said ofiice for designating the direction for trailic movements and for controlling the transmission of codes by said remote control system by which said traffic direction relays are operated to establish the corresponding direction for traiiic movements in said stretch and for also governing jointly with said signal control levers the transmission of codes by said remote control system by which said signal control relays are operated to clear said signals, an auxiliary relay at the oflfice, means for operating said auxiliary relay in response to the transmission of a control code provided such code is transmitted when the control lever for the signal at the end of the stretch which said electroresponsive means designates to be the entrance end is in its signal clear position, an indication relay at said office for each of said signals, each signal indication relay being operated when an indication is received that the associated signal is clear and being restored to its normal position when an indication is re ceived that the associated signal is at stop, means responsive to the indication code which is transmitted when a signal is cleared for restoring said auxiliary relay to its normal position, and locking means at said oiiice comprising normally closed contacts of said auxiliary relay and of said signal indication relays in a circuit for controlling said electroresponsive means, the opening of such contacts being effective to maintain the designated trafiic direction by preventing the energization of said electroresponsive means when said auxiliary relay or either of said signal indication relays occupies its operated position.

9. In direction selecting means for a stretch of railway track equipped with a signaling system governed jointly by trailic direction relays at opposite ends of the stretch so that at times the stretch is conditioned for trafiic movements in one direction and at other times for trainc movements in the opposite direction and having a signal at each end for governing traffic movements into the stretch and a signal control relay for each signal for manually governing the clearing thereof inaccordance with the condition of said signaling system, together withv a code type remote control system for transmitting control codes for controlling the signal control and trafiic direction relays from a central office and for transmitting indication codes for indicating trafiic conditions at said oiiice, in combination, a signal control lever at the ofiice for each of said signals, each of said levers being movable between a clear and a stop position, electroresponsive means at said office for designating the direction for traffic movements and for controlling the transmission of codes by said remote control system by which said traffic direction relays are operated to establish the corresponding direction for traflic movements in said stretch and for also governing jointly with said signal control levers the transmission of codes by said. remote control system by which said signal control relays are operated to clear said signals, an auxiliary relay at the office, means for operating said auxiliary relay in response to the transmission of a control code provided such code is transmitted when the control lever for the signal at the end of the stretch. which said electroresponsive means designates to be the entranceend. is in its signal clear position, means responsive to the indication code which is transmitted whena train enters the stretch for restoring, said auxiliary relay to its normal position, occupancy indication. means at said office which is operated when an indication is received that said stretch is occupied and is restored to its normal position when an indication is received. that said stretch is unoccupied, and locking means at said office comprising normally closed contacts controlled by said auxiliary relay and said occupancy indication means in a circuit for controlling said electroresponsive means, the opening of such contacts being effective to maintain the designated traffic direction by preventing the energization of said electroresponsive means. when said auxiliary relay or said occupancy indication means occupies its operated position.

10. In direction selecting means for a stretch of railway-track equipped with a signaling sys temgoverned jointly by trafiic direction relays at opposite ends of the stretch so that at times the stretch is conditioned for traiiic movements in one direction and at other times for traflic movements in the opposite direction and having a signal at each end for governing traffic movements into the stretch and a signal control relay for each signal for manually governing the clearing thereof in accordance with the condition of said signaling system, together with a code type remote control system for transmitting control codes for controlling the signal control and trafiic direction relays from a centralofiice and for transmitting indication codes for indicating trafic conditions at said oiiice, in combination, a signal control lever "at the oifice for each of said signals, each of said levers being movable between a clear and a stop position, electroresponsive means atv said office for designating the direction for trafiic movements and for controlling the transmission of codes by said remote control system by which said traffic direction relays are operated to establish the corresponding direction for traffic movements in said stretch and for also governing jointly with said signal control levers the transmission of codes by said remote control system by which said signal control relays are operated to clear said signals, an auxiliary relay at the oilice, means for operating said auxiliary relay in response to the transmission of a control code provided such code is transmitted when the control lever for the signal at the end of the stretch which said electroresponsive means designates to be the entrance end is in its signal clear position, means responsive to the indication code which is transmitted when a signal is cleared for restoring said auxiliary relay to its normal position, an indication relay at said oilice for each of said signals, each signal indication relay being operated when an indication is received that the associated signal is clear and being restored to its normal position when an indication is received that the associated signal is at stop, a circuit at said ofiice governed by said signal control levers for operating said electroresponsive means to change the designated trafiic direction, and locking means in said circuit comprising contacts of said auxiliary relay and of said signal indication relays which are closed only when said auxiliary relay and said signal indication relays occupy their normal positions.

.11. In direction selecting means for a stretch of railway track equipped with a signaling system governed jointly by trafiic direction relays at opposite ends of the stretch so that at times the stretch is conditioned for traffic movements in one direction and at other times for trafiic movements in the opposite direction and having a signal at each end for governing traffic movements into the stretch and a signal control relay for each signal for manually governing the clearing thereof in accordance with the condition of said signaling system, together with a code type remote control system for transmitting control codes for controlling the signal control and trafiic direction relays from a central office and for transmitting indication codes for indicating traffic conditions at said ofiice, in combination, a signal control lever at the office for each of saidsignals, each of said levers being movable between a clear and a stop position, electroresponsive means at said ofiice for desighating the direction for traffic movements and for controlling the transmission of codes by said remote control system by which said traffic direction relays are operated to establish the corresponding direction for traffic movements in said stretch and for also governing jointly with said signal control levers the transmission of codes by said remote control system by which said signal control relays are operated to clear said signals, an; auxiliary relay at the office, means for operating said auxiliary relay in response to the transmission of a control code provided such code is transmitted when the control lever for the signal at the end of the stretch which said electroresponsive means designates to be the entrance end is in its signal clear position, means responsive to the indication code which is transmitted when a train enters the stretch for restoring said auxiliary relay to its normal position, occupancy indication means at said ofiice which is operated when an indication is received that said stretch is occupied and is restored to its normal position when an indication is received that said stretch is unoccupied, a circuit at said office governed by said signal control levers for operating said electroresponsive means to change the designated traffic direction, and locking means in said circuit comprising contacts controlled by saidauxiliary relay and said occupancy indication means wihch are closed only when said auxiliary relay and said occupancy indication means occupy their normal positions.

12. In direction selecting means for a stretch of railway track equipped with a signaling system governed jointly by trafiic direction relays at opposite ends of the stretch so that at times the stretch is conditioned for trafiic movements in one direction and at other times for trafiic movements in the opposite direction and having a signal at each end for governing traihc movements into the stretch and a signal control relay for each signal formanually governing the clearing thereof in accordance with the condition of said signaling system, together with a code type remote control system for transmitting control codes for controlling the signal control and traffic direction relays from a central ofiice and for transmitting indication codes for indicating trafiic conditions at said ofiice, in combination, a signal control lever at the ofiice for each of said signals, each of said levers being movable between. a clear and a stop position, electroresponsivemeans at said' office for designatin the direction for traffic movements and for controlling the transmission of codes jointly with said signal control levers the transmission of codes by said remote control system by which said signal control relays are operated to clear said signals, a first auxiliary relay at the ofiice, means for operating said first auxiliary relay in response to the transmission of a control code provided such code is transmitted when the control lever for the signal at the end of the stretch which said electro-responsive means designates to be the entrance end is in its signal clear position, a second auxiliary relay, means for operating said second auxiliary relay in response to the transmission of a con trol code provided such code is transmitted when said first auxiliary relay occupies its operated position and the control lever for the signal at the end of the stretch which said electroresponsive means designates to be the entrance end is in its stop position, means responsive to the indication code transmitted when a train enters the stretch for restoring said first auxiliary relay to its normal position, means controlled by said second auxiliary relay for rendering any indication code transmitted when said second auxiliary relay is in its operated position effective to restore said first and second auxiliary relays to their normal positions, and

locking means at said oflice comprising a nor-' mally closed contact of said first auxiliary relay in a circuit for controlling said electroresponsive means, the opening of such contact being effective to maintain the designated traffic direction by preventing the energization of said electroresponsive means when said first auxiliary relay occupies its operated position.

13. In direction selecting means for a stretch of railway track equipped with a signaling system governed jointly by trafiic direction relays at opposite ends of the stretch so that at times the stretch is conditioned for trafiic movements in one direction and at other times for trafiic movements in the opposite direction and having 7 a signal at each end for governing traflic movements into the stretch and a signal control relay for each signal for manually governing the clearing thereof in accordance with the condition of said signaling system, together with a code communication system of centralized control including a field station for each end of the stretch for controlling the signal control and traffic direction relays from a central ofiice and for indicating trafiic conditions at said ofiice, in combination, electroresponsive means at said office for designating the direction for traffic movements and for controlling thetransmission of codes by said remote control system to said field stations by which said trafiic direction relays are operated to establish the corresponding closed contact of said auxiliary relay in a circuit for controllingi'said electroresponsive-means, the opening of said contact being effective to maintain the designated traific direction when said auxiliary relay occupies its operated position 14. In directionselecting means for a stretch of railway track equipped with a signaling system. governed jointly by trafiic direction relays at opposite ends of the stretch so that at times the stretch is conditioned for trafiic movements in one direction and at other times for trafiic movements in the opposite direction and having a signal at each end for governing traffic movements into the stretch and-a signal control relay for each signal for manually governing the clearing. thereof in accordance with the condition of said signaling system, together with a code communication system of centralized control including a field station for each end of the stretch for i controlling the signal control and traffic direction relays from a central ofiice and for indicating traffic conditions at said office, in combination, electroresponsive means at said office for designating the direction for trafiic movements and for controlling the transmission of codes by said remote control system to said field stations by which said trafiic direction relays are operated to establish the corresponding direction for traffic movements in said stretch, an auxiliary relay at said office, means for operating said auxiliary relay in response to the transmission of a control code, provided such code is one for operating a signal control relay to clear a signal at a field station at one end of the stretch, another relay at the ofiice, means for operating said other relay in response to the transmission of another control code to said field station, provided such other control code is transmitted when said auxiliary relay occupies its operated position and is one for restoring said signal control relay to normal to put the associated signal to stop,.means for restoring said auxiliary relay to its normal position in response to the transmission of an indication code from said field station to the office showing that a train has entered the stretch, means effective only when said other relay is in its operated position for restoring said auxiliary relay to its normal position in response to the transmission of an indication code from said field station to the office irrespective of the character of such code, and means at said otfice comprising a normally closed contact of said auxiliary relay in a circuit for said electroresponsive means the opening of such contact being efiective to maintain the designated traffic direction by preventing the energization of said electroresponsive means when said auxiliary relay occupies its operated position.

15. In direction selecting means for a stretch of railway track equipped with a signaling system governed jointly by trafiic direction relays at opposite ends of the stretch so that at times the stretch is conditioned for trafiic movements in one direction and at other times for traffic movements in the opposite direction and having a signal at each end for governing trafiic movements into the stretch and a signal control relay for each signal for manually governing the clearing thereof in accordance with the condition of said signaling system, together with a code communication system of centralized control including a field station for each end of the stretch for controlling the signal control and trafiic directionrelays from a central oiiice and for indicatall munication system including at the ofiice a delivery relay for each of said field stations, each of said delivery relays being operated temporarily during receipt of an indication code from the associated field station, in combination, electroresponsive means at said office for designating the direction for trafiic movements and for controlling the transmission of codes to said field stations by said remote control system by which said trafiic direction relays are operated to establish the corresponding direction for trafiic movements in said stretch, an auxiliary relay at said ofiice, means for operating said auxiliary relay in response to the transmission of a control code provided such code is one for operating a signal control relay to clear a signal at a field station at one end of the stretch, another relay at the office, means for operating said other relay in response to the transmission of another control code to said field station, provided such other control code is transmitted when said auxiliary relay occupies its operated position and is one for restoring said signal control relay to normal to put the associated signal to stop, a first means for restoring said auxiliary relay to its normal position rendered eilective upon the reception of an indication code from said field station at the ofiice showing that a train has entered the stretch, a second means for restoring said auxiliary relay to its normal position, said second means becoming efiective when said other relay and the delivery relay are both operated, and means at said ofiice comprising a normally closed contact of said auxiliary relay in a circuit for said electroresponsive means, the opening of such contact being effective to maintain the designated trafiic direction by preventing the energization of said electroresponsive means when said auxiliary relay occupies its operated position.

16, In locking means for a stretch of railway track equipped with a signaling system governed by trafiic control means so that at times the stretch is conditioned for traffic governed by a first signal and at other times is conditioned for trafiic governed by a second signal and having signal control means for manually controlling the clearing of said signals in accordance with the condition of said signaling system together with a code type communication system for controlling said signal and trafiic control means from a remote oifice and for indicating traffic conditions at said ofiice, in combination, electro responsive means at said o ifice controlling the transmission of codes by said remote control system by which said trafiic control means is operated to prepare the stretch for trafiic governed by said first or said second signal and for designating at the ofiice. whether tramc governed by said first or said second signal may move in said stretch, an auxiliary relay at the office, means for operating said auxiliary relay in response to the transmission of a control code provided such code is one for clearing a signal by operation of said signal control means, means for restoring said auxiliary relay to its normal position in response to an indication code transmitted when a train enters the stretch, and means at said ofiice efiective only when said auxiliary relay occupies its normal position for operating said electroresponsive means to select the direction for trafiic movements in said stretch.

17. In locking means for a, stretch'of railway

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