US2210052A

US2210052A - Railway traffic controlling apparatus

Info

Publication number: US2210052A
Application number: US232378A
Authority: US
Inventors: Henry S Young; Ronald A Mccann
Original assignee: Union Switch and Signal Inc
Current assignee: Hitachi Rail STS USA Inc
Priority date: 1938-09-29
Filing date: 1938-09-29
Publication date: 1940-08-06
Anticipated expiration: 1957-08-06

Description

Aug. 6, 1940. H. s. YOUNG ET AL 2,210,052

RAILWAY TRAFFIC CONTROLLING APPARATUS I Filed Sept. 29, 1958 II H G +2 X 5 la T21 T22 T195 6 v 10 B 17 35 B I] 22 Z] 25 1 1 29 I [1 1: Tm] T 122 1 A121 Aim Ll Q15 f? 304' Flagman 6 012227011 INVENTORS Henry 5Y0 and 0 C of the current source.

Patented Aug. 6, 1940 UNITED STATES PATENT OFFICE RAILWAY TRAFFIC CONTROLLING APPARATUS Application September 29, 1938, Serial No. 232,378

Claims.

Our invention relates to railway traflic controlling apparatus, and has for an object the provision of novel and improved means for governing a control device whereby a momentary loss of train shunt within a control section does not affect the operation of the control device. Other objects and advantages of our invention'will appear as the specification progresses.

We shall describe one form of apparatus embodying our invention, and shall then point out the novel features thereof in claims.

The accompanying drawing is a diagrammatic View showing a preferred form of apparatus embodying our invention when applied to the control of a highway crossing signal.

Referring to the drawing, the reference characters I and la designate the trafiic rails of a stretch of railway track X over which traffic moves in both directions. Rails I and rare divided by means of the usual insulated rail joints 2 into relatively long sections D-E and FG separated from each other by a relatively short section EF, which is intersected by a highway H. Located adjacent the intersection is a highway crossing signal S, which may be of any suitable type, but which, as here shown, is an audible signal in the form of an electric bell. Sections D-E and F-G usually will be of such length suitable to provide an adequate warning period to highway users of the approach of a train to the intersection. Section E-F will usually be of such length as to completely include the intersection.

Sections D-E, E-F, and F--G are provided with track circuits comprising in each instance a suitable source of current, such as a track battery 3, connected across the track rails at one end of the section, and a track relay, designated by the reference characters TRI, TR2, and TR3, respectively, connected across the track rails at the other end of the section.

The reference characters SRI and SR2 designate stick relays associated with track relays TRI and TR3, respectively. Relay SRI is normally energized over a stick circuit passing from terminal B of a suitable source of current, such as a battery not shown, through front contact 6 of relay TRI, front contact 1 of relay SRI, and the winding of relay SRI to the other terminal The relay SR2 is normally energized over a stick circuit passing from terminal 13 through front contact I! of relay PR3, front contact I8 of relay SR2, and the winding of relay SR2 to terminal C. The relays SRI and SR2 are provided each with a first and a second pick-up circuit and which circuits will be described more fully hereinafter.

The reference character TERI designates a time element relay which is governed jointly by relay TRI and relay SRI, and the reference character TER2 designates a time element relay governed jointly by relay 'I'R3 and relay SR2. The time element relay TERI and TERZ may be of any suitable type, such as, for example, the type disclosed in the United States Letters Patent No. 2,114,895, granted on April 19, 1938 to H. E. Ashworth for Thermal relays. These relays are each provided with a normally open contact which closes within a predetermined interval, of, say, 10 seconds, after the relay is energized.

Two auxiliary relays ARI and AR2 are provided for checking the operation of the thermal relays TERI and TER2, respectively. The circuits for controlling the auxiliary relays ARI and AR2 will be pointed out later.

Directional control of the highway crossing signal S is established through the medium of an interlocking relay XR. The interlocking relay XR may be of any suitable type, such as, for example, therelay covered by United States Letters Patent No. 1,799,629, granted to W. K. Lockhart and T. J. OMeara on April 7, 1931. This type of relay is well-known and is characterized by the fact that when the left-hand winding WI is deenergized, the downward movement of the armature associated therewith operates a mechanical locking device which keeps the armature associated with the right-hand winding W2 locked up in approximately its mid position, so that the subsequent deenergization of winding W2 while winding WI is still deenergized cannot close back contact 24. Similarly, if the right-hand winding W2 is first to become deenergized, then back contact 25 is prevented from closing when the left-hand winding WI becomes deenergized during the interval that winding W2 is still deenergized. Relay XR is also provided with

front contacts

26 and 21 associated with windings WI and W2, respectively, which have what we shall term flagman adjustments. That is to say, each flagman contact remains closed when its associated armature is in its locked up position. Winding WI is provided with an energizing circuit which may be traced from terminal B through front contact I II in multiple with front contact I I of relay TRZ, front contact 9 of relay SRI, back contact I2 of relay ARI in multiple with the front fiagman contact 26 of winding WI of relay XR, and the winding WI of relay XR to terminal C. Winding W2 is provided with an energizing circuit passing from terminal B through front contact Ill in multiple with front contact II of relay 'I'RZ, front contact I9 of relay SR2, back contact 32 of relay AR2 in multiple with front flagman contact 21 of winding W2 of relay XR, and the winding W2 of relay XR to terminal C. Hence, windingWI of relay XR is governed jointly by track relay TR2, stick relay SRI and auxiliary relay ARI, but at times front flagman contact 26 of winding WI nullifies the control exerted by relay ARI over winding WI. Winding W2 is governed jointly by relay TR2, relay SR2, and

relay AR2, with front flagman contact 21 of winding W2 at times nullifying the control of relay AR2 over winding W2.

The immediate operating circuit for signal S passes from terminal B through back contact 25 of winding WI or back contact 24 of winding W2 of relay XR, and the winding of signal S to terminal C.

Theapparatus is in its normal condition, as shown in the drawing, when sections DE, E,F, and FG are unoccupied. In this condition of the apparatus, the track relays TRI, TR2, and TR3 are energized, the stick relays SRI and SR2 are energized over their respective stick circuits, windings WI and W2 are energized, and relays TERI, TERZ, ARI, AR2, and signal S are deenergized.

Having thus described the various elements of the apparatus embodying our invention, we shall explain their operation for an eastbound train, and shall at the same time trace the circuits con-' trolling each part of the apparatus.

Whenan eastbound train, that is, a train op-' erating from left to right in the drawing, enters section D E, relay TRI is deenergized'and releases to open front contact Band thereby open the stick circuit for relay SRI with the result that relay SRI becomes deenergized and releases to open front contact I and thereby open its stick circuit, and closes back contact 8 to prepare an energizing circuit for relay TERI. The release of relay SRI also opens front contact 9 and thereby opens the control circuit for winding WI so that winding WI releases to close back contact 25' and thereby initiate the operation of signal S.

In the event a momentary loss of train shunt occurs while the train occupies section D--E, the track relay TRI might pick up, following the fluctuation in the train shunt, but the operation of the control device, that is, signal S, is unaffected, since relay TRI ordinarily will release, again prior to the completion of the cycle of operation necessary to effect the energization of winding WI and the consequent deenergization of signal S. This cycle of operation is initiated when front contact 6 of relay TRI closes when the track relay picks up, and consists of the following steps: The energization of relay TERI until such time as contact I3 closes; the energization and deenergization of relay ARI; and the energization of relay SRI, which relay then completes the control circuit for winding WI. For a more complete understanding of our invention, we shall describe in detail this cycle of operation of the apparatus, it

being understood that relay TRI is assumed to remain energized for the entire interval required for the apparatus to complete is cycle of operation.

'The energization of relay TERI is effected over a circuit passing from terminal B through front contact 6 of relay TRI, back contact 8 of relay SRI, the operating element of relay TERI, and back contact I4 of relay ARI. to terminal C. The

energization of relay TERI for its predetermined time interval will result in contact I3 closing the pick-up circuit for relay ARI, this circuit passing from terminal B through front contact 6 of relay TRI, back contact 8 of relay SRI, contact I3 of relay TERI, and the winding of relay ARI to terminal C. Relay ARI picks up upon becoming energized to close front contact I5 and thereby complete a stick circuit for that relay passing from terminal B through front contact I5 of relay ARI, contact I3 of relay TERI, and the winding of relay ARI to terminal C, and to open back contacts I2 and It, the opening of back contact I l opening the energizing circuit for the operating element of relay TERI, and the opening of back contact I2 opening the previously traced control circuit for winding WI. of relay ARI also completes the second pick-up circuit for relay SRI, which may be traced from terminal B through front contact 6 of relay TRI, front contact I6 of relay ARI, and the winding of relay SRI to terminal C, whereupon relay SRI picks up to close front contact 9 interposed in the control circuit for winding WI, but winding WI remains deenergized until the control circuit for winding WI is completed at back contact I2 of relay ARI. This control circuit is completed when the contact I3 of relay TERI opens at the end of a short interval after the operating element of the relay TERI is deenergized. The opening of contact I3 of relay TERI opens the. stick circuit for relay ARI, with the result that relay ARI releases to close back contact I2 and thereby complete the control circuit for winding WI, and to open front contact I6 and thereby open the pick-up circuit for relay SRI, the relay SRI being retained energized over its stick circuit. The complete cycle of operation aforementioned is now completed, so that in the event that relay TRI is not released, winding WI be* comes energized to deenergize signal S. However, relayTRi remaining picked up for the full interval required for theapparatus to complete its cycle of operation is a very remote possibility, since ordinarily a loss of shunt within a control section is only of very few seconds duration, and the train shunt is normally restored and relay- TRI released prior to the control circuit for winding WI being completed, with the result that the control circuit for winding WI remains open and the operation of signal S is not affectedby the' picking up and releasing of the track relay in response to variations in train shunt in the control section. It is understood, of course, thatthe period of time required for such cycle of operations may be selected by proper proportioning of the parts to best suit the different conditions existing at each location wherein such apparatus is installed.

When the train enters section EF, relay TRZ- releases to open front contacts I0 and II which are interposed in the control circuits for windings WI and W2, with the result that winding W2 releases to its locked position.

When the train enters section F-G, relay TR3 releases to open front contact I'I, thereby opening the stick circuit for relay SR2 with the result that relay SR2 is deenergized and releases to open front contacts I8 and I9, and to close back contact 20. The opening of front contact I8 of relay SR2 opens its stick circuit, the opening of front contact I9 opens the previously traced control circuit for winding W2, while the mg circuit-for relay TER2.

When the train vacates section DE, relay TRI picks up to close front contact 25 and thereby complete a first pick-up circuit for relay SRi, which circuit may be traced from terminal B through back contact 22 of relay TR3, front contact 2| of relay TR! and the winding of relay SR! to terminal C. Relay SR! becomes energized and picks up to close front contact '1, thereby completing its stick circuit including front contact 6 of relay TR!, and to close front contact 9, thereby preparing the control circuit for winding Wl. It should be noted that when the train vacates the section D-E,relay SR! is picked up over its first pick-up circuit to prepare the control circuit for winding Wl independently of the time element relay TERS, with the result that the delay period of the time element relay resulting from the complete cycle of operation necessary to close the second pick-up circuit for relay SR! is not ordinarily employed.

When the train vacates section E-F, relay TR2 picks up to close front contacts Hi and l l and thereby completes the control circuit for winding WI, whereupon winding W i picks up to open back contact 25 with the result that the operation of signal S is terminated.

It should be noted that back contact I?! of relay AR! must be closed in order to enable relay TRZ to complete the control circuit for winding WI. It can be seen that in the event the above described cycle of operations has been effected while the train occupied section DE, back con-- tact l2 of relay AR! will be closed only if contact l3 of relay TERI is opened, since contact l3 governs the stick circuit for relay ARl. It follows that back contact E2 of relay ARI provides a check upon the normally open position of con tact !3 of relay TERl, since if the relay fails to open contact l the signal S will continue to operate and so denote the improper condition existing within the apparatus.

When the train vacates section F-G, relay PR3 picks up to open back contact 22 and thereby open the finest pick-up circuit for relay SR!, and to close front contacts ll and 2 53, the closing of front contact l'l completing an energizing circuit for relay TERfi passing from terminal B through front contact I? of relay back contact 2B of relay SR2, the operating element of relay TERZ and back contact 2% of relay ARE to terminal C. At the end of its predetermined time interval, relay TERZ closes contact 2i. thereby completing a pick-up circuit fer relay A132 passing from terminal B through front contact ll of relay TR3, back contact of relay SR2, contact 29 of relay HERE, and the winding of relay ARZ to terminal C. Relay AR? energized and picks up to close front contact 3i! and thereby complete a stick circuit for that relay through front contact 38 and contact 29 of relay TERB, and to close front contact 35, thereby completing the second pick-up circuit for relay passing from terminal B through front contact I! of relay TR3, front contact 3! of relay ARR and the winding of relay SR2 to terminal C. The piclnng up of relay AR? also opens back contact 28 which opens the circuit for the operating element of relay TERZ and back contact which is interposed in the control circuit for winding W2.

Relay SR2 now picks up to open back contact 20, thereby opening the pick-up circuit for relay ARZ, and to close front contacts i8 and iii, the closing of front contact l8 completing the stick circuit for relay SR2, and the closing of front contact l9 completing the control circuit for winding W2 passing from terminal B through front contact Ill and front contact I I, in multiple, of relay TR2, front contact IQ of relay SR2, front flagman contact 21 of winding W2, and the winding W2 of relay XR. to terminal C, with the result that winding W2 picks up.

After relay TERZ has been deenergized for a brief interval, contact 29 opens to open the stick circuit for relay ARE, with the result that relay ARZ releases and the apparatus is restored to its normal condition.

In the event that a loss of shunt occurs in section F--G while the train is receding from the intersection, the directional control of signal S is maintained by virtue of the cycle of operation eifected by relays TER2, AR2 and SR2, as described in connection with the train vacating the section FG. It follows that since a loss of train shunt is ordinarily of quite short duration, the shunt will be restored and the track relay TR3 released prior to the apparatus completing its cycle, with the result that the winding W2 re mains deenergized so that the directional control of signal S is not affected.

It should be noted front flagman contact 27 of winding W2 provides a shunt path around back contact 32 of relay ARE in the control circuit for winding W2. It should further be noted rat although back contact 32 of relay AR? may be opened by virtueof the failure of relay TER'l to open contact 29 and thereby open the stick circuit for relay ARZ, whereby relay ARZ is maintained energized, the winding W 2 will pick up to restore the interlocking relay XR to its normal condition when section F-G is vacated by the eastbound train. In the event that relay TER2 fails to open contact 29, it can be seen that when a westbound train approaches the intersection, signal S will operate properly to warn the high way users of the approach of a train, and after the train has cleared the intersection, signal S will continue to operate to indicate the failure of relay TERZ to open contact 29 since the control circuit for winding W2 is open at back contact 32 of relay ARZ and at front flagman contact 2! of winding W2. It follows that back contact of relay ARE serves to check the normally open position of contact 29 for relay TERZ by causing the signal S to continue to operate when relay TERZ fails to open its contact.

The operation of the apparatus of a westbound train is similar to the operation just described for an eastbound train, audit is believed therefore that this latter operation will be apparent from the foregoing description together with an inspection of the drawing without further detailed explanation.

Although we have herein shown and described only one form of 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 combination, a stretch. of railway track provided with a track circuit including a track relay, a stick relay normally energized over a stick circuit including a front contact of said track relay, a time element relay, circuit means for energizing said time element relay including a front contact of said track relay and a back contact of said stick relay, an auxiliary relay, an energizing circuit for said auxiliary relay including sald circuit means together witlia contact of said time element relay closed only in the energized condition of the time element relay, a pick-up circuit for said stick relay including a front contact of said track relay and a front contact of said auxiliary relay, and a control circuit including a front contact of said stick relay.

2. In combination, a stretch of railway track intersected by a highway and divided into a first and a second track section extending in opposite directions from the intersection, a highway crossing signal located at such intersection, a track circuit for said first section including a first track relay, a track circuit for said second section including a second track relay, a first stick relay normally energized over a stick circuit governed by said first track relay, a second stick relay normally energized over a stick circuit governed by said second track relay, a first time element relay governed jointly by said first track relay and said first stick relay, a second time element relay governed jointly by said second track relay and said second stick relay, a first auxiliary relay; a pick-up circuit for said first auxiliary relay governed jointly by said first stick relay and said first time element relay; a stick circuit for said first auxiliary relay governed by said first time element relay; a second auxiliary relay; a pickup circuit for said second auxiliary relay governed jointly by said second track relay and said second time element relay; a stick circuit for said second auxiliary relay governed by said second time element relay, a pick-up circuit for said first stick relay governed jointly by said first track relay and said first auxiliary relay, a pick-up circuit for said second stick relay governed jointly by said second track relay and said second auxiliary relay, an,interlocking relay having a first winding and a second winding, an operating circuit for said signal including a back contact of each of said windings of the interlocking relay, a control circuit for said first winding governed jointly by said first stick relay and said first auxiliary relay, and a control circuit for said second winding governed jointly by said second stick relay and said second auxiliary relay.

3. In combination, a stretch of railway track intersected by a highway and divided into a first and a second track section extending in opposite directions from the intersection, a high way crossing signal located at such intersection, a track circuit for said first section including a first track relay, a track circuit for said second section including a second track relay, a first stick relay normally energized over a stick circuit governed by said first track relay, a second stick relay normally energized over a stick circuit governed by said second track relay, a first time element relay governed jointly by said first track relay and said first stick relay, a second time element relay governed jointly by said second track relay and said second stick relay, a first auxiliary relay; a pick-up circuit for said first auxiliary relay governed jointly by said first track relay, said first stick relay and said first time element relay; a stick circuit for said first auxiliary relay governed by said first time element relay. a second auxiliary relay; a pick-up circuit for said second auxiliary relay governed jointly by said second track relay, said second stick relay and said second time element relay; a stick circuit for said second auxiliary relay governed by said second time element relay, a pick-up circuit for said first stick relay governed pointly by said first track relay and said first auxiliary relay, a pickup circuit for said second stick relay governed jointly by said second track relay and said second auxiliary relay, an interlocking relay having a first winding and a second winding, an operating circuit for said signal including a back contact of each of said windings of the interlocking relay, a first control circuit for said first winding governed jointly by said first stick relay and said first auxiliary relay, a second control circuit for said first winding governed jointly by said first stick relay and a flagman contact of said first winding of the interlocking relay, a first control circuit for said second winding governed jointly by said second stick relay and said second auxiliary'relay, and a second control circuit for said second winding governed jointly by said second stick relay and a flagman contact of said second winding of the interlocking relay.

4. In combination, a stretch of railway track intersected by a highway and divided into a first and a second track section extending in opposite directions from the intersection, a track circuit for said first track section including a first track relay, a track circuit for said second track sec-- tion including a second track relay, a first stick relay normally energized over a stick circuit controlled by a front contact of said first track relay, a second stick relay normally energized over a stick circuit controlled by a front contact of said second track relay, a first time element relay governed jointly by said first track relay and said first stick relay, means governed by said first time element relay for establishing a first pick-up circuit for said first stick relay, a second pick-up circuit for said first stick relay governed jointly by said first track relay and said second track relay, a second time element relay governed jointly by said second track relay and said second stick relay, means governed by said second time ele ment relay for establishing a first pick-up circuit for said second stick relay, a second pick-up circuit for said second stick relay governed jointly by said second track relay and said first track relay, operating means for operating said signal when a train approaches the intersection, a first control circuit for said operating means governed by said first stick relay and a second control circuit for said operating means governed by said second stick relay.

5. In combination, a stretch of railway track divided into a first section and a second section separated from each other by a third section intersected by a highway, a highway crossing signal located at such intersection, a track circuit for said first section including a first track relay, a track circuit for said second section including a second track relay, a track circuit for said third section including a third track relay, a first stick relay normally energized over a stick circuit governed by said first track relay, a second stick relay normally energized over a stick circuit governed by said second track relay, a first time element relay governed jointly by said first track relay and said first stick relay, a second time element relay governed'jointly by said second track relay and said second stick relay, a first auxiliary relay; a pick-up circuit for said first auxiliary relay governed jointly by said first track relay, said first stick relay and said first time element relay; a stick circuit for said first auxiliary relay governed by said first time element relay, a second auxiliary relay; a pick-up circuit for said second auxiliary relay governed jointly by said second track relay, said second stick relay and said second time element relay; a stick circuit for said second auxiliary relay governed by said second time element relay, a pick-up circuit for said first stick relay governed jointly by said first track relay and said first auxiliary relay, a pick-up circuit for said second stick relay governed jointly by said second track relay and said second auxiliary relay, an interlocking relay having a first and a second winding, an operating circuit for said signal including a back contact of each of said windings of the interlocking relay; a control circuit for said first winding governed jointly by said third track relay, said first stick relay and said first auxiliary relay; and a control circuit for said second winding governed jointly by said third track relay, said second stick relay and said second auxiliary relay.

6. In combination, a stretch of railway track divided into a first section and a second section separated from each other by a third section intersected by a highway, a highway crossing signal located at such intersection, a track circuit for said first section including a first track relay, a track circuit for said second section including a second track relay, a track circuit for said third section including a third track relay, a first stick relay normally energized over a stick circuit governed by said first track relay, a second stick relay normally energized over a stick circuit governed by said second track relay, a first time element relay governed jointly by said first track relay and said first stick relay, a second time element relay governed jointly by said second track relay and said second stick relay, a first auxiliary relay; a pick-up circuit for said first auxiliary relay governed jointly by said first track relay, said first stick relay and said first time element relay; a stick circuit for said first auxiliary relay governed by said first time element relay, a second auxiliary relay; a pick-up circuit for said second auxiliary relay governed jointly by said second track relay, said second stick relay and said second time element relay; a stick circuit for said second auxiliary relay governed by said second time element relay, a pick-up circuit for said first stick relay governed jointly by said first track relay and said first auxiliary relay, a pick-up circuit for said second stick relay governed jointly by said second track relay and said second auxiliary relay, an interlocking relay having a first and a second winding, an operating circuit for said signal including a back contact of each of said windings of the interlocking relay; a first control circuit for said first winding governed by said third track relay, said first stick relay and said first auxiliary relay; a second control circuit for said first winding governed by said third track relay, said first stick relay and a fiagman contact of said first winding a first control circuit for said second Winding governed by said third track relay, said second stick relay and said second auxiliary relay; and a second control circuit for said second winding governed by said third track relay, said second stick relay and a flagman contact of said second winding.

7. The combination with a section of railway track having a track relay responsive to trafiic conditions in the section and a stick relay normally energized over a stick circuit including a front contact of the track relay, and a time element relay controlled over an energizing circuit which includes a front contact of the track relay and a back contact or" the stick relay, said time element relay having a time contact which is operated from its normal position to an operated position in a predetermined time interval of energization of the time element relay, of an auxiliary relay, an energizing circuit for said auxiliary relay including a front contact of the track relay and a back contact of the stick relay and the time contact of the time element relay in its operated position, and a pick-up circuit for the stick relay including a front contact of said auxiliary relay.

8. The combination with a section of railway track having a track relay responsive to traific conditions in the section and a stick relay normally energized over a stick circuit including a front contact of the track relay, and a time element relay controlled over an energizing circuit which includes a front contact of the track relay and a back contact of the stick relay, said time element relay having a time contact which is operated from its normal position to an operated position in a predetermined time interval of energization of the time element relay, of an auxiliary relay, a pick-up circuit for said auxiliary relay including a front contact of the track relay and a back contact of the stick relay and the time contact of the time element relay in its operated position, a stick circuit for said auxiliary relay including the time contact of the time element relay in its operated position, a pick-up circuit for the stick relay including a front contact of the track relay and a front contact of said auxiliary relay, and a control circuit including a front contact of the stick relay and also including a back contact of said auxiliary relay whereby the return of the time contact of the time element relay to its normal position is checked.

9. The combination with a section of railway track having a track relay responsive to trafllc conditions in the section and a stick relay normally energized over a stick circuit including a front contact of the track relay, and a time element relay controlled over an energizing circuit which includes a front contact of the track relay and a back contact of the stick relay, said time element relay having a time contact which is operated from its normal position to an operated position in a predetermined time interval of energization of the time element relay, of circuit means controlled by a front contact of the track relay and the time contact of the time element relay in its operated position for establishing a pick-up circuit for the stick relay, a control circuit controlled by the stick relay, and means controlled by said circuit means interposed in said control circuit to check the return of the time contact of the time element relay to its normal position.

10. In combination, a stretch of railway track divided into two outer sections and an intermediate section, said intermediate section being intersected by a highway and provided with a highway crossing signal located at such intersection, a track circuit including a track relay for each of said sections, two stick relays one for each of the track relays of said two outer sections and each stick relay normally energized over a stick circuit controlled by a front contact of its associated track relay, a first pick-up circuit for each of said stick relays controlled by the other of the track relays of said two outer sections, means controlled by each track relay of said two outer sections for establishing a second pick-up circuit for its associated stick relay in a predetermined time interval after such track relay picks up, whereby a momentary loss of train toward the intersection in said two outer sections but to operate said signal for railway trafiic moving in either direction in said intermediate section and terminate operation of said signal after railway trafiic clears said intermediate section.

HENRY S. YOUNG. RONALD A. McCANN.