US2625649A

US2625649A - Directional relay control circuits for railway signaling systems

Info

Publication number: US2625649A
Application number: US148967A
Authority: US
Inventors: Crawford E Staples
Original assignee: Westinghouse Air Brake Co
Current assignee: Westinghouse Air Brake Co
Priority date: 1950-03-10
Filing date: 1950-03-10
Publication date: 1953-01-13
Anticipated expiration: 1970-01-13

Description

3 c. E. STAPLES DIRECTIONAL RELAY CONTROL CIRCUITS FOR RAILWAY SIGNALING SYSTEMS 4 Sheets-Sheet l- Filed March 10, 1950 .v v. 0p

1 n W L d u W m AM u Mk5 m m NEW w. E Aw w w Eww aw HIS ATTORNEY Jan. 13, 1953 c. E. STAPLES DIRECTIONAL RELAY CONTROL CIRCUITS FOR RAILWAY SIGNALING SYSTEMS 4 Sheets-Sheet 2 Filed March 10, 1950 INVENTOR. Crawford E. Staples BY HIS ATTORNEY Jan. 13, 1953 c. E. STAPLES DIRECTIONAL RELAY CONTROL CIRCUITS FOR RAILWAY SIGNALING SYSTEMS 4 Sheets-Sheet 5 IN VEN TOR.

Unzwi'ord l1 Staples BY 60- in M His ATTOIZNY Filed March 10, 1950 mvwm as Jan. 13, 1953 c. E. STAPLES 2,625,649

DIRECTIONAL RELAY CONTROL CIRCUITS FOR RAILWAY SIGNALING SYSTEMS Filed March 10, 1950 4 Sheets-Sheet 4 1% CST-1*? n a N a nr-Lhufi 9 6* g..- L E ""QLA' "g l---l a Q r": E J L,

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E a a l l l INVENTOR.

Gmwibrdfl Staples HIS ATTORATEY Patented Jan. 13, 1953 DIRECTIONAL RELAY CONTROL CIRCUITS FOR RAILWAY SIGNALING SYSTEMS Crawford E. Staples, Turtle Creek, Pa., assignor to Westinghouse Air Brake Company, a corporation of Pennsylvania Application March 10, 1950, Serial No. 148,967

2 Claims. (Cl. 246-33) My invention relates to directional stick relay control'circuits used in railway signaling systems governing the movement of trafiic in stretches of single track in which trafiic moves in two directions. More particularly, my invention relates to improved directional stick relay control circuits for use in absolute permissive block signaling system employing cascade connected reversible coded track circuits, arranged so that the traffic direction is set up and the headblock signals are cleared by a control, which may be effected either manually or by a train entering an approach section, while the intermediate signals which are controlled solely by the track circuits, are cleared automatically in one direction or the other in accordance with the established trafiic direction.

Signaling systems of the absolute permissive block type provide for the control of traific moving in either direction in a single track stretch by means of headblock signals which display absolute or stop-and-stay indications and intermediate signals which display permissive or stop-then-proceed indications. The headblock signals control the movement of trafiic from passing sidings into the single track stretch, while the intermediate signals control the movement of traific that has passed a headblock signal and has entered the single track stretch. Each intermediate signal is controlled by an associated track relay and is provided with a directional stick relay normally arranged to become energized when its track relay releases in response to a train passing the associated signal at clear or approach. Each stick relay when energized prepares a circuit for energizing the next signal in the rear, governing tralfic movements in the same direction, so as to allow that signal to indicate approach as soon as the portion of the stretch in advance of the signal is vacated by a train and thus permits following movements in the stretch.

The directional stick relays have been con trolled in the past jointly by the track relays and by controls transmitted over line wires, but improved systems have been devised for efiecting' the control of the stick relays solely through the medium of the track rails so as to dispense with the necessity for control line wires. Systems of the latter type are shown in Letters Patent of the United States, Reissue No. 22,915, dated Septem-- ber 16, 1947, (original Patent No. 2,344,573, issued March 21, 1944) and Reissue No. 22,780 dated Au- 1 gust 13, 1946 (original Patent No. 2,344,333, issued March 14, 1944) granted respectively on applications filed by James J. Van Horn. The system of Van Horn Reissue Patent No. 22,915 makes use of normally deenergized reversible coded track circuits arranged so that after a traliic direction has been established by energizing the track circuits controlling the signals for the selected direction, the stick relays at the intermediate location are controlled by means of approach relays connected in the track circuits to respond to the approach of a train in the section in the rear of each signal. The system of Van Horn Reissue Patent No. 22,780 is in general similar to that of Reissue No. 22,915, except that the former makes use of normally steadily energized reversible coded track circuits, that is, the track circuits are normally supplied with noncoded energy.

An object of my present invention is to provide novel and improved means for controlling directional stick relays in non-line wire absolute permissibe block signaling systems, that is, ab-' solute permissive block signaling systems in which all controls for intermediate signals and directional stick relays are transmitted through the track rails and in which no line wires are used. My improved stick relay control may be used in non-line wire signaling systems in which track circuits are normally energized or normally deenergized, or are of the coded type normally supplied with non-coded energy. A more specific object of my invention is to provide novel and improved means for controlling these directional stick relays by the associated track circuit, so that each directional stick relay becomes energized when its associated track relay releases due to a train entering a corresponding track section in the established direction, but not when an opposing train overruns a headblock signal nor when the track circuit is deenergized in preparation for reversing the direction of traffic.

A further object of my invention is to provide improved means of the type described which is arranged so that the equipment of each intermediate signal location in the stretch is substantially self -contained and does not depend for its operation on special energy impulses transmitted over the track rails from an adjacent signal location.

Another object of my invention is to provide improved means of the type described which is arranged so that the operation of the equipment is independent of changes of operating conditions, such as changes in ballast resistance or in the voltage in the batteries from which energy is supplied to the track circuits.

In practicing my invention I provide, at each intermediate signal location, means for each signal operative upon shunting of its associated track relay, to sheet a momentary connection of a source of current and an auxiliary relay in series across the track rails of the section governed by that signal. The auxiliary relay is normally released and is arranged to become picked up only in response to current of the relatively large value caused to be drawn from the source when a train shunt is applied across the rails of the section at or near the signal location.

Thus the auxiliary relay will pick up due to the shunting of associated track relay by a train entering the section in the established trafuc' direction, but will not pick up upon operation of the track relay for any other cause, as for example, if the track relay is deenergized preparatory to reversing traffic direction in the stretch.

The intermediate signals may be approach lighted, in which event each such signal will be provided with an approach relay for governing the lighting of the lamp or lamps on the associated signal, with the approach relay for each signal arranged to be connected in series with a source of current across the rails of the section in the rear of the signal and proportioned to pick up only when a train approaches in that section toward the associated signal. The same source may be used at a double intermediate location for controlling the approach relay for one of the two signals at that location and the directional stick relay for the other of the two signals.

The specified objects of my invention, as well as other objects not specifically described above, are obtained by apparatus subsequently to be described and shown in the accompanying drawings.

The system shown and described in this application is closely related to that shown and described in a, copending application for Letters Patent of the United States, Serial No. 762,617, filed on July 22, 1947, by Arthur L. Jerome, for a Coded Traci: Circuit Railway Signaling System, which application is assigned to the same assignee as the present application, and this application contains claims to certain features which are shown but not claimed in the said Jerome application.

I shall describe one form of railway signaling system embodying my invention and shall then point out the novel features thereof in claims.

Referring to the accompanying drawings, Figs. 1A, 1B and 1C, placed side by side in the order listed with Fig. in at the left, and Fig. 1D placed beneath Fig. 1B, are diagrammatic views illustrating the track plan and wayside circuits and apparatus for a railway signaling system which embodies my invention. In this application only the portions of the wayside apparatus essential for the understanding of this invention have been shown and the remainder of the equipment may be arranged in any of several arrangements well known in the railway signaling art.

Similar reference characters refer to similar parts in each of the several views.

Referring to the drawings, I have here shown a stretch of single track railroad extending between the ends of two passing sidings, and over which trafiic may move in either direction. Movements of trains in and out of the sidings are directed by the track switches NV and SW, located at the ends of sidings X and 0, respectively. The movement of trains into the single track stretch is governed by wayside entering headblock signals located at the ends of the passing sidings, such as signals 2RA and 238 shown in Fig. 1A at the end of passing siding X, and the signals 4LA and QLB shown in Fig. 1C at the end of passing siding 0. Movement of trains leaving the single track stretch is governed by wayside leaving signals such as signals ELA and ZLB at siding X and signals RA and 5R3 at siding 0. Located at an intermediate point in the single track stretch is a pair of intermediate signals iiL and SR, which govern trairlc moving through the single track stretch. It will be seen, therefore, that each track switch and each wayside signal is designated by a number identifying its location, the signal designations also including the sulfur L or R to indicate the direction of trallic movements which the signal governs, that is, to the left or to the right, respectively.

Associated with the switches and signals are a plurality of relays which will be described in detail hereinafter. Each of these relays is identified by a characteristic letter or combination of letters, prefixed by the designation of the switch or signal with which it is associated.

Signals ERA, 2R8, 5L, 5R, GLA and #i-LB are of the well known color light type, having a green lamp Gr, a yellow lamp Y, and a red lamp R, which lamps when lit, indicate clear, approach, and stop, respectively. The detailed circuits for signals Z'LA, ZLB, ARA, and QRB are not shown, since they are not necessary for an understanding of my invention. The entering headblock signals are arranged to be continuously lighted, while the intermediate signals 6L and SR are arranged to be lighted only when the track section in the rear of the signal is occupied by a train, as will be subsequently described.

The stretch of track between the entering headblock signals ZRA and ZRB and ALA and 4L8 is divided into a plurality of track sections by the usual insulated joints to form track sections IT, 2R6LT, SR-4LT and ST. The track sections IT and 3T provide conventional detector track sections at the ends of the passing sidings and each have a conventional direct current track circuit including a track relay such as relay iTR, and a track battery such as ITB. The remaining track circuits for sections 2R-6LT and Elia-4LT, extending from the ends of the passing siding to the intermediate signals, are of the reversible coded type, which may be connected in cascade when the block includes two or more sections and provide means for controlling the signals for both directions to provide three indications and also for indicating at either end whether or not the single track stretch is occupied, without the use of line wires. The track relays ZR'I'R, fiLTR, SRTR and lLTR, and also the approach relays GEAR and GLAR associated with the coded track circuits of sections 2R$LT and (SR-4LT are code following relays of the biased polar type. These relays are constructed and arranged so that the contacts of the relays are normally biased to their released positions and will pick up when and only when energy flows through the winding in the direction indicated by the arrow thereon.

One form of code following relay of this general type is shown, for example, in Letters Patent of the United States No. 2,057,605, issued October 13, 1936, to Herman G. Blosser.

The periodically operating contacts of the code following relays are distinguished from those of the other quick acting relays by dotted lines indicating the alternative position of the contacts, and the contacts of slow acting relays are identified in the conventional manner by the vertical arrows thereon. It is to be understood that the slow acting relays having condensers bridged across their windings, such for example, as the relay ZRTF shown in Fig. 1A, have release delay periods of about five seconds.

Energy for the operation of the apparatus other than the track circuits is furnished by suitable sources of direct current, such as the batteries shown at each location, the positive and negative terminals of which are designated by the reference characters B and N, respectively.

As previously pointed out, my invention may be employed with various types of absolute permissive block signaling systems including those in which the headblock signals for traflic direc-- tion are subject to manual control from a remote oflice, such systems being commonly known as centralized traffic control systems. The system described herein for purposes of disclosure is of the centralized traflic control type.

Inasmuch as my invention relates only to wayside signaling apparatus, the centralized traffic control system by means of which the direction of energization of the signal circuits and the clearing of the headblock signals is made subject to manual control from the central ofilce is not shown herein, but it is to be understood that this is preferably a remote control system of the code type such as that disclosed in Letters Patent of the United States No. 2,229,249, issued January 21, 1941, to Lloyd V. Lewis, for Remote Control Systems, or in a modified form in a publication entitled Centralized Trafiic Control Systems-Time Code Scheme, Manual No. 506A, published by The Union Switch and Signal Company, Swissvale, Pennsylvania. For an understanding of my invention, it will suffice to point out that the remote control system has at each headblock location a field station which is connected with the control office by a line circuit over which codes are transmitted in either direction for selective communication between the ofice and the different stations, one at a time. The control codes transmitted to the station serve to operate a group of control relays of the stick polar type, in accordance with the positions of control levers at the oflice. Two such control relays are shown herein at each station, and these comprise a traffic relay such as relay ZRFS, Fig. 1A, which governs the direction of traffic movements in the single track stretch by cooperation with a similar relay lLFS at the opposite end of the single track stretch, shown in Fig. 1C, and also, includes to the reversal of the associated code signal conv trol relay 2RHS or ELI-IS. Each traffic relay when reversed, so as to close its contact enables the associated end of the stretch to become the exit end.- In this position the traffic relay supplies energy to the signal circuits for the block to enable the signals which govern tralfic movements toward its location to be cleared.

The present invention relates more particularly to the coded track circuit apparatus, and is an improvement on that disclosed in an applica- 6 tion for Letters Patent of the United States Serial No. 596,470, filed May 29, 1945, by Henry S. Young for Railway Traflic Controlling Apparatus. In the system of this Young application the coded track circuit are normally deenergized and are set up by manual control by reversing the traflic relay at the exit end of the single track stretch for the desired direction of traflic movement, and then reversing the code signal control ,relay for the entering signal at the other end of the single track stretch. The system of the Young application is also arranged so that when a train vacates the single track stretch and an indication of that fact has been transferred to the ofiice, the operated traffic relay is restored automatically to normal, and the wayside circuits are thereby restored to their normal deenergized condition. This mode of operation may be employed in connection with the track circuits of my invention, or they may be left energized until the reversal of the trafilc direction is required to thereby provide a normally energized system. It is also to be understood that the remote control system preferably includes means for preventing the operation of traffic and signal control relays except when under the proper traffic conditions, so that a signal cannot be put to stop by the operation of any lever other than its control lever, one arrangement suitable for this purpose being disclosed in the above-mentioned Young application.

In the coded track circuit system as disclosed herein, the coded currents are generated by code .transmitters of the pendulum type designated IBUCT and T at the various locations. These code transmitters are energized continuously at the headblock locations and when required at the intermediate locations and operate their contacts periodically at a rate of or '75 times per minute, respectively, to periodically operate a transmitter relay such as relay ZRCT, by which the coded energy of the selected frequency is supplied to the track rails. Each code following track relay, such as relay ZRTR, is provided with a slow release, front contact repeater relay, such as the relay 2RTF, which remains picked up as long as the track relay is responding to coded energy. The code responsive apparatus at the different signal locations is substantially similar and its operation will be understood from the description of that of Fig. 1A, where it will be seen that the closing of front contact a of track relay 2RTR in response to the supply of an impulse of coded energy to the winding of relay 2RTR establishes' an obvious circuit for supplying energy to the winding of relay ZRTF. Relay 2RTF is rendered slow in releasing its contacts by the condenser connected across the relay winding, so that the contacts of the relay will remain picked up during the intervals in which the control circuit of the relay is opened by the recurrent operation of contact a of relay ZRTR. When the contacts of relay ZRTF pick up, its front contact (1 establishes an obvious circuit for supplying energy to a code following repeater relay ZRTP each time that the relay 2RTR releases its contact a. Additionally, when relay ZRTF picks up, its contact b establishes a circuit for supplying energy to the primary winding of a decoding transformer 2DT over contact a of relay ZRTP. As the contacts of relay 2RTP are recurrently picked up and released in response to the code following operation of contact a of relay ZRTR, contact a of relay ZRTP alternately energizes the lower half and the upper half of the primary winding of decoding transformer ZDT. As a result, current is induced in asecondary winding of the transformer 2DT which current is mechanically rectified by contact b of relay ZRTP and supplied to the winding of a slow acting code detecting relay ZRH. It will be seen that the relay ZRH will be energized and picked up when and only when the track relay ZRTR is following code. Transformer 2DT also supplies code frequency energy to a decoding unit IBUDU which is of a type well known in the art. The decoding unit l8lDU is constructed and arranged so that it will supply energy of a value sufiicient to pick up the contacts of clear control relay 2RD when and only when the frequency of energy supplied to the decoding unit from transformer 213T is of the order of 180 cycles per minute. Accordingly, relay 2RD will be energized when and only when the code following relay ZRTR is responding to 180 code. The display of a green or clear aspect by the signals is governed by the clear control relay, as will be subsequently described.

The circuits for controlling track switches !W and 3W which lead to the passing tracks at the ends of the single track stretch have been omitted in order to simplify the drawings, and it will be understood that when switch IW is locked in its normal position as shown, a normal switch repeating relay INWP is energized, and when switch lW is locked in its reverse position, reverse switch repeating relay IRWP is energized. The circuits for these relays are completed over the contacts NW and RW of a circuit controller actuated by switch lW, as will be obvious from an inspection of the drawings. These relays serve to select the signal lighting circuits for signal ZRA or ZRB, in accordance with the position of the switch IW, the selected signal displaying a yellow aspect when the code detecting relay ZRI-I is energized alone, or displaying a green aspect when relay 2RD is also energized. The relays 3NWP and 3RWP associated with track switch 3W are similar in their operation and functions to relays INWP and lRWP described above.

The operation of the system is generally similar for both directions of trafiic movement and the circuits of Fig. 1C therefore, are similar to those of 1A, except they are oppositely directed. Likewise, the apparatus at the intermediate signal location of Fig. 1B is similar for eachdirection but oppositely directed. In Fig. 1B, but one set of decoding apparatus is used, this being arranged for either direction of operation depending upon which of the track relays is operated, and in addition a pair of directional stick relays, such as SRSR and ELSR, are provided for controlling energization of the track circuit system as required for following train movements in either direction, The directional stick relays are governed at times by an associated relay, such as the relays GLSAR and BRSAR, as will be subsequently described.

In describing in detail the operation of the system embodying my invention, it is assumed that the apparatus is in its normally deenergized condition, as shown. It will now be assumed that the operator desires to move a train from right to left through the single track stretch. By operation of the control levers at the control office, the trafiic relay ZRFS of Fig. 1A and the signal control relay GLHS of Fig. 1C are operated to their reverse positions.

At this time, since signal ZLA is at stop, the circuit for supplying energy to the signal repeater relay 2LAPC is interrupted and the contac'ts of relay 2LAPC are released. The circuit for. controlling relay ZLAPC is not shown but it may be of any of several well known types in which the relay is energized when and only when signal ZLA displays a green or yellow aspect. Accordingly, a circuit is established to supply energy of ?5 code frequency to the transmitting relay ZRCT. This circuit may be traced from terminal B, over contact a of code transmitter TECT, over back contact a of relay 2LAPC, front contact a of relay (TR, over reverse polar contact a. of relay ZRFS and through the winding of relay ZRCT to terminal N, whereby the contacts of the relay ZPLCT are operated at '75 code rate.

When contact a of relay ZRCT picks up, it in terrupts the connection of track relay ERTR to the rails of section 2R-6LT, and establishes a circuit for supplying energy from the battery ZRTB through the Winding of relay 2RTR and the rails of section ZR-SLT to the winding of relay BLTR shown in Fig. 1B. This circuit may be traced from the positive terminal of battery ZRTB, over front contact a of relay ZRCT, through the winding of relay ZR'IR, over rail 5 of section 2R-6LT, over back contact 2: of relay ELSAR, through the winding of relay ELTR from left to right, over back contacts a and b of relay SLCT in multiple, through rail 6 of section 2R--LT, and to the negative terminal of battery ZRTB. The direction of flow of energy is such that the contact of relay ZRTR, remains released, and the contact of relay GLTR, picks up.

When contact a of relay ERCT releases, the circuit traced above is interrupted, and the contact of relay SLTR releases. Accordingly, at this time the coded energy supplied to the left hand end of the rails of section 2R6LT causes the contact of relay GLTR to be operated at the '75 code rate. The recurrent operation of the contact of relay ELTR causes energy to be supplied over front contact a of the relay to the winding of front contact repeater relay BLTF, and as a result the contacts of relay BLTF pick up and remain picked up as long as relay BLTR, is following code.

When contact a of relay iLTF picks up, it establishes a circuit for supplying energy to the code following repeater relay GTP each time relay GLTR releases its contact a. This circuit may be traced from terminal B, over back contact a of relay GLTR, front contact a of relay GLTF, back contact a of relay GR'I'F, and through the winding of relay 6T)? to terminal N. As a result, the relay STP will recurrently pick up and release its contacts in accordance with the operation of contact a of relay BL'I-R. The primary winding of decoding transformer BDT, and as a result, alternating current is incircuit including front contact c of relay BLTF and contact a of relay iiTP. The recurrent operation of contact a of relay STP causes energy to be alternately supplied to the upper and lower portions of the primary winding of transformer GDT, and as a result, alternating current is reduced in the secondary winding of the transformer. This energy induced in the secondary winding is rectified mechanically by contact I) of relay BTP, and is supplied to the winding of the code detecting relay 51-1 to thereby cause the contacts of relay 6H to pick up and remain picked up as long as relay (ST)? is following code. Additionally, energy is supplied from decoding transformer EDT to the decoding unit I80DU, but

9 since the code rate at this time is only '75 cycles per minute, the energy supplied from the decoding unit iBiIDU to the relay 6D is insufficient to pick up the contacts of relay 6D.

When relay 6H picks up, its contact a establishes a circuit for supplying energy to the operating Winding of code transmitter IBBCT, and contact b of relay 6H establishes a circuit for supplying energy to the transmitting relay 6RCT, which circuit may be traced from terminal 13, over front contact a of code transmitter ISOC'I, front contact In of relay 6H, over front contact d of relay GLTF, over back contact a of relay BRSR, and through the winding of relay BRCT to terminal N. As a result, the contacts of relay GRCT are picked up and released at the 180 code rate. a

When the contacts of relay ERCT pick up, a circuit is established to supply energy from battery GRTB to relay ALTR, Fig. 1C. This circuit may be traced from the positive terminal of battery ERTB, over front contact b of relay BRCT, through the winding of relay BRHR, over back contact b of relay BRSAR, to the section rail 6 of section 6R-4LT. An additional low resistance SLAR to the negative terminal of battery ERTB.

The relay BLAR and resistor R2 associated therewith are selected and adjusted So that the value of energy which flows through the approach relay ELAR at this time is insufficient to pick up the relay contact. The direction of flow of energy is such that relay ALTR will pick up its contact and the contact of relay ERTR. will remain released. The shunting of the winding of relay GRTR by front contact a of relay GRCT affords a lower resistance to the fiow of energy in the circuit traced above. When the contacts of relay SRCT release, the circuit traced above is interrupted and contacts of relay ALTR release. Accordingly, at this time, the contact of relay 4LTR of Fig. 1C is picked up and released 180 times per minute in response to the coded energy supplied over the rails of section SR-4LT.

Each time relay 4LTR picks up, energy is supplied over front contact a to the winding of front contact repeater relay ALTF, so that at this time, the contacts of relay 4LTF are picked up, and since relay 4LTF is rendered slow in releasing by the condenser connected across its winding, the relay contacts remain picked up as long as relay 4LTR is following code. Each time contact a of relay ALTR releases, energy is supplied over an obvious circuit including front contact a, of relay 4L'IF to the winding of relay lLTP. Accordingly, the contacts of relay 4LTP are picked up and released 180 times per minute in accordancewith the operation of contact a of relay 4LTR.

The primary winding of decoding transformer 4DT is now supplied with energy by an obvious circuit including front contact 12 of relay 4LTF and contact a of relay 4LTP. The recurrent operation of contact a of relay 4LTP causes energy to be alternately supplied to the upper and lower portions of the primary winding of decoding transformer 4DT, and as a result, an alternating current is induced in the secondary winding of the transformer having a frequency corresponding to this code rate, which at this time is 180 cycles per minute. This energy is rectified mechanically by the contact b of relay ALT? and supplied to the winding of code detector relay ALE to thereby cause the contacts of relay 4LH to pick up and remain picked up as long as relay 4L'I'P is following code. Additionally, energy is supplied from the decoding transformer 4DT to the decoding unit lSBDU and since this energy has a frequency of 180 cycles per minute, the decoding unit lBODU supplies sufficient energy to the relay lL-D to pick up its contacts.

Since it is assumed that the code signal control relay :iLI-IS has been reversed by the central ofiice operator and since switch 3W is assumed to be in its normal position, so that relay 3NWP is picked up, the picking up of relays 4LH and 4LD establishes a circuit for supplying energy to the green lamp of signal 4LA. This circuit may be traced from terminal B, over reverse polar contact a of relay lLHS, over front contact b of relay 3TB, over front contact a of relay 3NWP, over front contact a of relay lLH, front contact a of relay 41D and through the green lamp G of signal ALA to terminal N. Accordingly, at this time signal 4LA will display a green aspect, indicating "clear.

If the operator now clears signal ZLA by means of circuits not shown, the relay ZLAPC will become picked up, and its contact a transfers the circuit for supplying energy to relay 2RCT from contact a of code transmitter T to contact a of code transmitter ISGCT. As a result, relay ZRCT operates its contacts times per minute and the supply of energy from battery 2R'I'B to the rails of section ZR-BLT is coded at that rate.

Relay BLTR, Fig. 13, will now operate its contacts 180 times per minute in response to the 180 code supplied to its winding, and repeater relay GTP also operates its contacts 180 times per minute.

Accordingly, energy of a frequency of 180 cycles per minute is supplied from decoding transformer EDT to the decoding unit I80DU, which now supplies suificient energy to the relay 6D to cause the relay to pick up its contacts, thereby conditioning the signal 6L to display a green aspect when energy is supplied to its lamp.

The movement of a train from right to left through the single track stretch will now be traced, assuming that the signals ZLA, 6L and 4LA have been conditioned to indicate clear as above described.

When the train moves past signal ALA and enters detector section 3T, detector track relay 3TB is shunted and its contacts release. Contact I) of relay BTR. interrupts the circuit previously traced for supplying energy to the green lamp G of signal 4LA and establishes an obvious circuit to supply energy to the red lamp R of the signal.

It is to be understood that at this time the code Signal control relay GLHS is restored automatically to normal and an indication of the occupancy of section 3T is transmitted to the control office as described in the manual identified above.

When the train enters section BR4LT, the relay ALTR is shunted and its code following operation ceases. Contact a of relay zLTR releases and remains released at this time, and the supply of energy to relay 4LT? is cut off as a result, but it retains its contacts picked up until the energy stored in the condenser connected across its winding is dissipated. The contacts of relay 4LT? are picked up continuously for this time interval, but energy is no longer supplied to relays QLH and QLD from the transformer ADT and the contacts of these relays will release, further interrupting the circuit for the green lamp G of signal 4LA.

Subsequently the contacts of relay 4LTF release, interrupting the supply of energy to relay GLTP and to the primary winding of transformer GDT.

At this time, relay BRCT, Fig. 1B, continues to operate its contacts, supplying coded energy from battery ERTB through the circuit including resistor R2 in multiple with the winding of relay SLAR. As a result of the shunting effect of the wheels and axles of the train, the current supplied to the rails from battery ERTB increases as the train approaches signal SL. The various parts of the equipment are arranged and proportioned so that when the train advances with in a substantial distance of the signal GL, as for example, 4000 feet, the value of current which flows through the winding of approach relay SLAR becomes sufiicient to cause the relay to operate its contact in response to the impulses of energy flowing in the relay winding. Each time contact a of relay BLAR. picks up, energy is supplied to the slow release approach repeater relay 6LAP by the circuit which is traced from terminal B, over front contact a of relay ELAR, and through the winding of relay eLAP to terminal N. Accordingly, relay SLAP is energized at this time and its front contact a establishes the circuit for supplying energy to the green lamp G of signal 5L, which circuit may be traced from terminal B, over front contact a of relay SLAP, front contact d of relay 5H, over front contact a of relay 5D, and through the green lamp G of the signal to terminal N, thus causing signal EL to display a green aspect, indicating clear.

When the train passes signal EL and enters section 2R-8LT, relay SLTR is shunted and its contact a releases and remains released and cuts off the supply of energy to relay fiLTF. However, the relay GLTF is slow in releasing and after release of relay BLTR, the circuit including back contact a of relay SLTR for supplying energy to relay GTP is established and the contacts of relay GTP remain picked up for a substantial time interval. The cessation of operation of the contacts of relay STP cuts off the supply of energy from the transformer SDT to relay 6H and ED and these relays release after a relatively short time interval which is less than the time required for relay fiLTF to release. When contact at of relay SH releases, the supply of energy to the green lamp G of signal 6L is interrupted, and the circuit is established for supplying energy to the red lamp R of the signal.

The relay ELTF and ERTF are selected and arranged with condensers of sufficient capacity so that these relays will remain picked up for a comparatively long time interval after the supplyof energy thereto has been interrupted by the release of the associated track relay. As previously pointed out, this time interval may be of the order of five seconds, for example.

Accordingly, there will be a substantial time interval between the release of relay 6H and the release of relay 6LT after the supply of energy to each of these relays has been cut off by the cessation of operation of the contact of relay SLTB. During this time interval, a circuit is established for supplying energy to the winding of the stick control relay ELSAR. This circuit may be traced from terminal B, over back contact a of relay 6H, over back contact 12 of relay ELSE, over front contact I) of relay fiLTF, and through the winding of relay iLSAR to terminal N. Accordingly, the relay ELSAR will be picked up during the interval between the time at which relay 6H releases, and the time at which relay SLTF releases.

When the contacts of relay SLSAB pick up, energy is supplied from the battery ELTB through the upper winding of the double wound stick relay SLSR. to the rails of section 2R-6LT, over the circuit which may be traced from the posi- 1 tive terminal of battery SLTB, through the upper winding of relay GLSR, over front contact a of relay ERSAR, through rail 5 of section 2R-BLT, through the wheels and the axles of the train occupying the section, through rail 5 of section 2RELT, and from thence over front contact 2) of relay QLSAR to the negative terminal of battery ELTB. The parts are proportioned and arranged so that with the resistance in the circuit traced above at a comparatively low value, such as will be obtained when the train has just entered the section, the relay SLSR will be picked up by the value of energy which flows through its upper winding at that time. When relay tLSR is picked up by the energy flowing through its upper winding, it establishes a stick circuit for itself, which circuit supplies energy to the lower winding of relay BLSR. This stick circuit may be traced from terminal B, over back contact a of relay 5H, over front contact I) of relay ELSE, and through the lower winding of relay ELSE. to terminal N.

When relay SLSR picks up, its back contact 1; interrupts the circuit previously traced for supplying energy to the relay ELSAR, and relay GLSAR subsequently releases thereby cutting off the supply of energy to the circuit including the upper winding of relay GLSR. However, at this time the stick circuit previously traced serves to keep the relay fiLSR energized until relay GE is again picked up.

A short time later, relay GLTF releases and its front contact b additionally interrupts the circuit for supp-lying energy to relay EELS-AR, but if relay BLSR is picked up by this time, the circuit is already interrupted.

At this time the operating winding of code transmitter 'IECT, Fig. 1D, is supplied with energy by an obvious circuit including front contact c of relay BLSR.

When contact 12 of relay 6H releases due to the entrance of the train in the section 2R6LT. the circuit previously traced for supplying energy coded at 180 times per minute to the transmitting relay GRCT is interrupted. Shortly thereafter, relay GLSR picks up in the manner described above and its front contact 1) establishes a circuit for supplying energy coded at times per minute to the transmitting relay BRCT. This circuit may be traced from terminal 13 at front contact a of relay l5CT,'over front contact (1 of relay BLSR, over back contact a of relay BRSR, through the winding of relay SRCT to terminal N.

As a result, energy is now supplied to the rails of section 6R4LT at the '75 code rate, and in the event the rear portion of the train still occupies the section BR--4LT, the approach relay GLAR will now operate its contact at the 75 code rate, and the relay SLAP will remain energized. The

release time of relay SLAP is made suiiicientlylong to bridge the time necessary for the equip- 13 ment to operate to change the code speed of relay GRCT from 180 to 75 times per minute.

When the train under discussion vacates the section BBL-4LT, the removal of the shunt decreases the amount of current supplied thereto from the battery BRTB, and as a result the flow of energy through the winding of relay ELAR falls below the value necessary to pick up the contact of relay BLAR and its contact releases and remains released. Accordingly, energy is no longer supplied to relay SLAP over the circuit including front contact a of relay GLAR, and after a time interval the contacts of relay GLAP releases.

When contact a of relay ELAP releases, it interrupts the circuits previously traced for supplying energy to the lamps of signal 6L, and as a result, the red lamp R of signal L is extinguished.

At the time, as previously explained, energy coded '75 times per minute is supplied to the rails of section 5RiLT by the operation of the contacts of transmitting relay GRCT, and when the section is vacated relay 4LTR responds to the 75 code supplied over the rails of section SR-ALT energizing relaysALTF and iLI-I in a manner similar to that previously described.

However, since the contacts of relay ALTP are operating at 75 code rate, the relay ALD does not receive suflicient energy from decoding transformer 4DT and the decoding unit IEGDU to pick up its contacts at this time. Consequently, if relay 4LHS is again reversed by the operator, signal ALA will be cleared in a manner similar to that previously described, except that, since relay 4LD is released the signal Will display a yellow aspect, indicating that the next signal is displaye ing, or is in condition to display, a red aspect.

As the train passes the signal 2LA, and enters detector track section 1T, the detector track relay ITR is shunted and its contacts release.

When contact a of relay I TR releases, the circuit previously traced for supplying energy to transmitting relay ZRC'I is interrupted so that coded energy is not supplied to the rails of section 2R5LT after the train vacates that section. Additionally, it is to be understood that when the train under consideration enters section IT, signal 2LA will be put to stop, and as a result, the relay ZLAPC will be deenergized and its contacts will release.

When the train vacates the section IT, the relay ITR picks up, and contact a of relay ITR again establishes the circuit for supplying energy to relay 2RCT. However, since the relay ZLAPC is released at this time, the circuit is governed by contact a of code transmitter J5CT, so that relay ZRCT supplies energy coded at the 75 code rate from battery LRTBto the rails of section 2R6LT.

The relay BLTR follows the coded energy supplied thereto over the rails of section 2R-6LT, and as a result, the contacts of relays BLTF and 8H pick up, as previously described. When contact a of relay 6H picks up, it interrupts the stick circuit previously traced for relay BLSR, and relay GLSR releases its contacts. When relay ELSR releases its front contact d, the circuit previously traced for supplying energy to the relay GRCT over contact a of code transmitter 150T is interrupted, and additionally, the relase of contact c of relay ELSE interrupts the supply of energy to the operation winding of code transmitter 150T.

The operating winding of code transmitter I80CT is now energized by the circuit including front contact a of relay 6H. Front contact o of relay 6H, and front contact 11 of relay BLTF again establishe the circuit for controlling relay tRCT over the contact (1 of code transmitter lBllCT. Also, the front contact d of relay 6H, and back contact d of relay 6D prepares the circuit for supplying energy to the yellow lamp of signal 6L should an approaching train cause the relay SLAP to pick up, as previously described.

With the contacts of relay GRCT operating at the code rate, energy is supplied from battery SRTB to the rails of section (FR-4LT at the rate of 180 impulses per minute. Response of relay dLTR to the coded energy supplied thereto causes the relays ALTF, dLl-I, and llLD to pick up, as previously explained. Energization of relay GLD may be employed in any suitable manner to indicate that the entire single track stretch is vacant, but this means is not part of this invention and has been omitted in order to simplify this disclosure.

With the single track stretch unoccupied, and the traflic relay ZRFS reversed to set up the direction of movement from right to left, as described above, it is assumed that the operator at the control ofiice restores the trafiic relay ERFS to normal.

When contact a of relay ZRFS opens, the supply of energy to relay ZRCT is cut oil. As a result. coded energy is no longer supplied from battery ZRTB over the rails of section ERr-BLT to relay ELTR, and relay GLTR releases and remains released.

As previously explained, the release of contact a of relay GLTR results in the release shortly thereafter of the contacts of relay 51-1, but the contacts of relay BLTF remain picked'up for a relatively long time interval after release of relay GLTR.

When contact a of relay 6H releases, it establishes the previously traced circuit for supplying energy over back contact b of relay ELSR, and front contact 17 of relay BLTF to the winding of relay GLSAR. Accordingly, the contacts of relay GLSAR pick up and connect the battery SLTB across the rails of section ZR-SLT in series with the upper winding of the stick relay SLSR.

At this time, since section 2R5L-T is assumed to be unoccupied, the value of energy which flows through the upper winding of relay GLSR is insufficient to pick up the contacts of the relay. As a result, the relay GLSR remains released, until the release time of relay BLTF expires. When relay BLTF releases, its front contact b interrupts the circuit for supplying energy to the winding of relay SLSAR, so that relay GLS-AR releases and its contacts a and b disconnect the battery GLTB and the upper winding of relay ELSE from the section rails. Accordingly, it will be seen that relay GLSR is not picked up at this time.

It is apparent that at this time with the section 2R--6LT unoccupied, when the battery SLTB and the upper winding of relay BLSR. are connected in series across the section rails, energy may flow over the section rails 5 and 6 of section 2R-$LT and through the winding of relay ZRTR. However, it will be noted that the direction of flow of energy through the winding of relay ZRTR is in the direction such that the contacts of thi relay will not pick up, so that any possibility of a false operation of relay 2RTR at this time is avoided.

When relay 6H releases its contacts, front contact a interrupts the supply of energy to code transmitter i80CT, and front contact in of relay 6H interrupts the circuit for supplying energy to relay GRCT over contact a of code transmitter H001, and since relay BLSR does not pick up at this time to supply energy over its front contact b and contact a. of code transmitter it-CT to the winding of relay ERCT, the contacts of relay ERCT remain released.

As a result, coded energy is no longer supplied from battery GRTB over the rails of section v fiR-4LT to the winding of relay ALTR, and relay tLTR releases, which results in the release of relays QLTF, lL-TP, ALI-I and tlLD, as previously explained.

The system is now restored to its normal or deenergized condition as shown in the drawings.

From the foregoing, it will be seen that the directional stick relays, such as relay ESL-SR is energized when the code operation of the associated track relay cease as a result of a train entering the corresponding track section at the entrance end thereof, but is not energized if the code operation of the track relay ceases when the section is not occupied.

This result is secured by providing at each intermediate signal location means effective upon release of the code detecting relay governed by a track relay at that location to temporarily connect. the associated track battery and an auxiliary relay, in the form of a winding of a multiplewinding stick relay, in series across the rails of the track section in advance of a signal. The auxiliary relay is adjusted so that energy suhicient to pick up the relay contact is supplied from the track battery to the relay winding only if a train is present at that end of the track section, and the relay is additionally governed by the code detecting relay so that the relay if picked up will remain picked up as long as the section is occupied.

When the track battery is connected across the track rails at the end of a track section in series with the winding of the stick or auxiliary relay, the energy supplied to the winding of the stick relay is of a high value if a train occupies that end of the section but is of a low value if the track section is not occupied, or if a train is present in a distant portion of a track section so that a considerablc length of track rail is included in the circuit of the track battery and approach relay.

Occupancy of, the battery or feed end portion of a track section produces much greater increase in the value of the energy supplied from the track battery through the winding of the stick relay than is produced by the variations in other conditions, such as changes in ballast resistance or in the voltage of the track battery. Accordingly, at the time the code detecting relay releases the stick relay may be adjusted to respond only to energy of relatively high value so that if that end of the tracksection is not occupied, the stick relay Wlll not respond to energy of the value supplied as a result of high battery voltage or low ballast resistance, or as a result of both conditions, but so that the stick relay will be certain to respond if that end of the track section is occupied.

As a result, this method of controlling the directional stick relay insures that the relay will be picked up to cause coded energy to be supplied t the track stretch behind the train when release of a code detecting relay is caused by occupancy of a track section, and at the same time it insures that variation in operating conditions will not cause the directional stick relay to be improperly picked up when release of a code detecting relay occurs because the supply of coded energy over the rails of a track section is cut oil for the purpose of deenergizing the track circuit apparatus.

My invention is advantageous in that no control pulse need be transmitted from the locations of each end of the single track block to the intermediate signal location, or from one intermediate signal location to another, to cause the system to assume its deenergized condition as is required in some systems. If the supply of coded energy from battery ZRTB, for example, is interrupted during the time when the system is set up for trafiic moving from right to left, if no train is occupying the section ZRFBLT' the equipment at the intermediate signal location BL6R will assume its deenergized condition, as previously explained and will out ofi the supply of coded energy to section 6R-4LT, tothereby cause the release of the relays flLI-I and 4L1) at the other end of the single track stretch.

An additional advantage which is gained from this arrangement is that it causes all the opposing signals governing traffic in the single track stretch to assume the stop position in case a train overruns the entering headblock signal at the exit end of the stretch. If a train moving from left to right should pass signal ZR-A at a time when signals 6L and GLA are cleared for a train moving from right to left, the entrance of the overrunning train into detector section IT will cause relay iii? to release with the result that its front contact a interrupts the circuit for relay 2RCT. Accordingly, the supply of coded energy to section 2R-6LT is cut off, and as previously explained, the equipment of signal 6L and also of signal 4LA is restored to its deenergized condition with the result that the signals indicate stop.

The equipment operates in a manner similar to that described in the foregoing when the single track stretch is conditioned for traflic movements from left to right, when a. train moves through the stretch from left to right, and when the system is being deenergized after such a move, and a detailed description of the operation of the equipment is deemed unnecessary.

It is to be understood that although only one set of intermediate signals, BL and GR, is shown in the drawings, the invention is not limited to this arrangement and any number of intermediate signals may be provided if necessary. Additionally, the conventional cut sections and hand operated track switches equipped with electric locks be interposed as desired without affecting the operation of the arrangement of the equipment embodying my invention.

Although I have herein shown and described only one form of directional relay control circuits for railway signaling systems embodying my invention, it is to be 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 my invention.

Having thus described my invention, what I claim is:

1. In a coded track circuit signaling system, in combination, a stretch of railway track comprising adjoining first and second track sections, first code transmitting means for at times supplying coded energy of a first polarity to the rails of said first section at the end thereof remote from said second section, a first code following track relay connected across the rails of said first track section at the end thereof nearest said second section and responsive only to energy of said first polarity supplied thereto, second code transmitting means for at times supplying energy of a second polarity to the rails of said first section at the end thereof adjacent said second section, a second code following track relay connected across the rails of said first section at the end thereof remote from said second section and responsive only to energy of said second polarity supplied thereto, a slow release relay energized as a result of operation of said first code following track relay, means operative upon release of said slow release relay for momentarily disconnecting said first track relay from the rails of said first section and for connecting in series across the rails of said first track sectionat the end thereof nearest said second track section a battery and a first winding of an auxiliary relay, the polarity of said battery being such that said battery is ineffective to cause operation of said second code following track relay, said auxiliary relay having normally released contacts which become picked up when and only when there is supplied through said first winding energy of the value which is supplied when the portion of said first track section nearest said second track section is occupied by a train, a second winding of said auxiliary relay, a stick circuit for supplying energy to said second winding when the contacts of said slow release relay are released and the contacts of said auxiliary relay are picked up, means for supplying coded energy to the rails of said second section while said slow release relay is picked up, and means responsive to the picking up of the contacts of said auxiliary relay for supplying coded energy to the rails of said second section while said slow release relay is released.

2. In a coded track circuit signaling system, in combination, a stretch of railway track comprising adjoining first and second track sections, first code transmitting means for at times supplying coded energy of a first polarity to the rails of said first section at the end thereof remote from said second section; a first code following track relay responsive to energy of said first polarity, a code transmitting relay, a track battery, an approach relay, a directional stick relay having a first and a second winding, and a directional stick control relay, all located at the end of the first section adjacent said second section; means including said code transmitting relay for at times connecting said first code following track relay across the rails of said first section and for at other times recurrentlyconnecting said track battery and said approach relay in series across the rails of said section to energize the rails of said section with energy of a second polarity, approach controlled means governed by said approach relay, a second code following track relay located at the end of said first section remote from said second section and responsive to energy of said second polarity, a first and a second slow release relay energized in response to the operation of said first code following track relay, said second slow release relay remaining picked up for a time interval subsequent to the release of said first slow release relay on cessation of operation of said first code following track relay, first circuit means for picking up said directional stick control relay during the interval in which said first slow release relay is released and said second slow release relay is picked up, second circuit means efiective when said directional stick control relay is picked up for connecting said track battery and the first winding of said directional stick relay in series across the rails of said first section independently of the connections of said approach relay, said first code following track relay, and said code transmitter relay, to thereby momentarily energize the rails of said first section, said second circuit means being arranged so that the momentary energization is of said first polarity and ineffective to operate said second code following track relay, said directional stick relay having normally released contacts which become picked up when and only when there is supplied through said first winding energy of the value which is supplied when the portion of said first track section nearest said second track section is occupied by a train, a stick circuit for supplying energy to said second winding when the contacts of said first slow release relay are released and the contacts of said directional stick relay are picked up, means for supplying coded energy of a first distinctive type to the rails of said second section while said first slow release relay is picked up, and means effective upon picking up of the contacts of said directional stick relay for supplying coded energy of a second distinctive type to the rails of said second section as long as said first slow release relay is released.

CRAWFORD E. STAPLES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,342,488 Preston Feb. 22, 1944 2,349,460 Phinney et al May 23, 1944 2,400,005 Jerome May 7, 1946