US2681985A - Highway crossing signal control system - Google Patents

Description

June 22, 1954 w us HIGHWAY CROSSING SIGNAL CONTROL SYSTEM Filed Sept. 50, 1950 Patented June 22, 1954 HIGHWAY CROSSING SIGNAL CONTROL SYSTEM William H. Claus, DownersGrove, 111., assignor to Westinghouse Air Brake Company, a corporation of Pennsylvania Application September 30, 1950, Serial No. 187,797 9 Claims. (01. 246-130) My invention relates to highway crossing signal control systems, and particularly to a system for providing proper operation of a highway crossing signal under a variety of different traffic conditions in the track stretch adjacent the crossing.

It is general practice in highway crossing signal control systems to initiate operation of the highway crossing signal at least twenty seconds before a train arrives at the intersection so that My system provides warning times of substantially equal duration regardless of the speed at which a train travels toward the intersection. To this end, I provide a number of speed measuring sections in the approach portion of track and equip each with a timing device which will operate whenever a train travels the speed measuring section with which it is associated at less than a predetermined speed. The timing de- 10 vices operate to select one or another of a pluusers of the highway will have adequate warning rality of control sections for initiating the opof the trains approach. In systems employing eration of the signals in such a manner that optrack circuits an operating period of at least eration of the signals is determined in accordtwenty seconds is usually obtained by locating anoe with the speed of the train travelling tothe entrance point of the first control section ward the intersection so as to initiate operation encountered by a train travelling toward the of the signals when the train is within approxintersection a distance from the crossing at least imately twenty seconds travel time from the crossequal to that which would be travelled in twenty ing. To obtain proper operation in the event a seconds by a train travelling at maximum autrain stops or delays as at a station after it has thorized speed. The first control section is usucaused the signals to be set into operation, I ally provided with a track relay which releases utilize a track relay to control a timing device to set the signals into operation when a train which operates at the end of a predetermined enters that section, and if succeeding sections are time to discontinue operation of the signals. employed each is also provided with a track re- Switching movements in and out of a control seclay which releases whenever the section is '00- tion are also accommodated without excessive cupied to maintain the signals in operation unperiods of operation of the signals. Circuit means til the train passes over the crossing. controlled by track switches are provided t Although a system of the above described type move the control sections which contain such will insure that the signals are operated for at switches from the control of the signals during least the requisite time for all trains approachon switching movements, so that operation of t ing the intersection, it may also result in unduly signals is not obtained unless the train advances long periods of operation at times inasmuch as toward the crossing and enters the adjoining the signals are set into operation when a train control section. I provide directional control of first enters the control stretch of track and such the signals, that is, prevent the signals from operation is continued as long as any control operating while a train recedes from the crosssection is ccupied so that prolonged operation ing on a single track stretch, by means of a sewill be provided for trains which travel at subrles of interlocking relays arranged with t stantially less than high speed. This may therewindings of each controlled over adjacent track fore unnecessarily obstruct highway traffic. Prosections. One winding of each interlocking relay longed operation will also occur if a train stops 1s available under proper conditions t Set t or slows down on a control stretch of track as signals into operation for a train travelling t at a station before reaching the intersection, or Ward the crossing and the other winding of each if a t n engages in switching movements on a Int rlocking relay is utilized to latch up the concontrol stretch of track at a siding. I O tficts e fi st and so prevent the signals from course, necessary and usual to provide means opoperating While a tram is receding from the erative when a train recedes from the crossing crossing. on a Single track stretch to prevent operation It is therefore an object of my invention to of the signals after the train clears the intersecprovide a novel and improved highway Crossing non signal control system of the type described which I propose to provide a highway crossing signal will provide for proper operation of the signals control system arranged to insure that the requiin any of the aforementioned situations. site warning time is given for high speed trains, Another object of my invention is the provision and incorporating novel and improved means for of novel and improved means operated by a train providing proper periods of operation of the sigtravelling toward the intersection for initiating ml in any of t aforementioned situations. operation of the crossing signals at one or another 3 of several points in the track travelled by the train in its approach to the intersection, the particular point at which operation is to begin being determined by the speed with which the train approaches the crossing.

A further object of my invention is the provision of novel and improved means for discontinuing the operation of the highway crossing signals when a train which has caused the signals to be set into operation stops or slows down as at a station before reaching the intersection.

It is a still further object of my invention to provide novel and improved means for avoiding the setting into operation of the signals if a train enters the control stretch from a siding, and to provide for such operation for the train only if it advances toward the crossing to enter the control section adjacent the track section containing the siding switch.

It is yet another object of my invention to provide novel and improved means for providing directional control of the signals so as to prevent their operation while a train recedes from the crossing over a single track stretch equipped with my system.

Other important objects and characteristic features of my invention will become apparent from the following description.

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

The accompanying drawing is a diagrammatic view showing one form of apparatus embodying my invention.

Referring now to the drawing, the reference characters I and la designate the rails of a stretch of track intersected at grade by a highway H. Highway crossing signals designated by the reference characters XS, which may take any one of a number of suitable forms, but which are for the sake of simplicity shown as bells, are located adjacent the intersection. The signals are controlled by an operating relay OR, as is obvious from an inspection of the drawing.

Insulated joints designated by the reference characters 2 divide the track into a plurality of successive adjoining track sections. As shown, the stretch may include four such sections AT, BT, CT and DT, all of which lie to one side of the intersection as shown and may therefore be considered as approach sections, and another section XT which extends over the crossing. Sections BT and CT as shown include track switches BW and CW, respectively, each of which establishes a route between the rails l and Id of the main line and one or more sidings not shown, and each switch is provided with a circuit controller contact I which it operates in such a manner as to close the contact only when the switch is reversed for a movement into or out of the siding. Each of the track sections is provided with a track circuit comprising a track battery 3' and a track relay connected respectively to the rails at opposite ends of the section, the track relay for each section being designated by the reference character R with a suitably distinguished prefix corresponding to the reference character of its associated section.

As will be made clear hereinafter, certain of the approach sections are utilized as operating sections at all times, another or other approach sections are utilized at times as operating sections and at other times as speed measuring sections, while still another or other approach sections are utilized at all times as speed measuring sections. As shown, sections AT and BT are arranged for utilization as speed measuring sections and each is provided with a timing device as in the form of time element relays ATER. and BTER. provided respectively for sections AT and ET. The time element relays ATER and BTER may be of any suitable type which is arranged to pick up and operate its contacts after the completion of an operating cycle which requires the relay to be energized for a predetermined period of time. These relays may for example be of the oscillating armature type shown and described in Patent No. l,966,965, granted on July 17, 1934, to Branko Lazich et al. for Electrical Relays. The contacts of relays ATER and B'IEPt are shown on the drawing with an upwardly directed arrow therethrough, indicating that these relays are slow in picking up their contacts. Each time element relay is controlled so as to become energized when its associated section is occupied provided the adjoining section toward the intersection is vacant, and if picked up is provided with a stick circuit when the adjoining section becomes occupied. That is to say, when section AT is occupied with section BT vacant, relay ATER associated with section AT is energized over an operating circuit extending from one terminal 13 of a suitable source of current such as a battery not shown, through front contact l i of relay BTR of the adjoining section BT, back contact iii of relay ATR and the winding of relay ATER to the other terminal N of the source of current. If with relay ATER picked up to close its front contact 33, section BT becomes occupied, relay ATER is provided with a stick circuit which includes its own front contact 33 and back contact l I of relay BTR. Relay BTER is similarly provided with operating and stick circuits controlled by relays BTR and CTR as will be evident from an inspection of the drawing, it being noted that the pickup circuit for relay BTER is also controlled by a relay BTHSPR hereinafter referred to. The time element relays are employed in a manner to be made clear hereinafter to obtain substantially uniform periods of operation of the crossing signal under different speeds of operation of trains approaching the crossing.

The approach sections BT, CT and DT as shown, are arranged to be utilized as operating sections, and thus it will be noted that section BT at times is utilized as a timing section, and at other times as an operating section. Each operating section has associated therewith an interlocking relay designated by the reference characters XR with a suitably distinguishing prefix, the interlocking relays BXR, CXR and DXR being associated respectively with sections BT, CT and DT. Each interlocking relay XR is characterized by the provision of two windings 4 and 5 and a mechanical locking arrangement controlled by the windings in such a manner that with both armatures picked up the release of either latches up to the other if it should release before the first armature is picked up. The winding 4 of each interlocking relay is provided with a front flagman contact l3 which is arranged to open when the armature of that winding releases to a full-down position but which does not open when the armature with which it is associated is released to a latched up position. Taking interlocking relay BXR as an example, if the armature of winding 4 is released when the armature of winding 5 is picked up, flagman contact i3 of winding 4 opens, but if Winding 4 become deenergized when the armature of winding 5 is released, flagman contact l3 of winding 4 is prevented from opening. A relay having an interlocking mechanism of the type which may be adapted to provide this operation is shown for example in Letters Patent of the United States No. 1,799,629, granted April 7, 1931, to W. K. Lockhart and 'I'. J. OMeara.

The one winding 4 of each interlocking relay XR is normally energized over a circuit controlled by the track relay of the associated operating section and the other winding 5 is normally energized by a circuit controlled by the track relay for the next adjacent section toward the crossing. Thus, relay BXR associated with operating section BT has its one winding l normally energized over a circuit controlled by front contact I2 of relay BTR while the other winding 5 of relay BXR, is normally energized over a circuit governed by front contact 25 of relay CTR for the next adjacent section CT toward the crossing. Similarly, winding 4 of relay CXR is energized over a circuit controlled by front contact 25 of relay CTR, and winding 5 of relay CXR is energized over front contact 3| of relay D'I'R; while relay DXR. has its winding 4 controlled by front I contact 3| of relay DTR, and its winding 5 energized over front contact 32 of relay XTR.

Certain of the operating sections are provided with other time element relays designated by the reference characters THR with a suitably distinguishing prefix for discontinuing the operation of the crossing signals, if such operation has been initiated for a train which slows down to a very low speed or stops in the associated section. As

shown, the two sections BT and CT are respectively provided with timing relays BTHR and CTHR which relays may be of the thermal relay type shown and described in Letters Patent of the United States No. 2,114,895, granted to Harry E. Ashworth on April 19, 1938, for Thermal Relay. The contacts of these relays are shown on the drawing with a double-headed arrow therethrough, indicating that these relays are slow in picking up and slow in releasing their contacts. Each of the thermal time element relays BTHR and CTl-IR is provided with a stick relay designated by the reference character THSR with a distinguishing prefix, and each is energized when its associated operating section is occupied provided that its stick relay is released. Each thermal relay if picked up completes a pick up circuit for its associated stick relay which then picks up to complete a stick circuit for itself and interrupt the energization of the thermal relay. For example, thermal relay BTHR has associated therewith a stick relay BTHSR, and is energized when its associated section is occupied if relay BTHSR is released, over a circuit including back contact l2 of relay BTR and back contact I8 of relay BTHSR. If relay BTHR picks up, its front contact l9 completes for relay BTHSR a pick up circuit which includes back contact l2 of relay BTR, and when relay BTHSR picks up it closes its front contact It to complete an obvious stick circuit for its winding, and to openthe pick up circuit for relay BTI-IR. Relay BTHSR also has another pick up circuit which may be established, independently of its associated thermal relay BTHR, when track switch BW is reversed to close its circuit controller contact I and section BT is occupied, this pick up circuit extending from terminal B through back contact I 2 of relay BTR, contact I of switch BW closed in the reverse position of the switch, and the winding of relay BTHSR to terminal N. The thermal relay CTHR 6 provided for section CT, and its associated stick relay CTHSR are similarly controlled by the track relay CTR for its associated section and by contact l of the track switch CW included in that section, as will be apparent from an inspection of the drawing.

A track section which has associated with it a time element relay THR and stick relay TI-ISR, as described above, and which also functions as a speed measuring section, has its speed measuring time element relay TER subject to the con trol of the stick relay TI-ISR, and to effect this conveniently a repeater relay THSPR is provided for the controlling stick relay THSR. Thus, for example, section ET which is equipped with speed measuring time element relay BTER and also with time element relay BTI-IR and stick relay BTHSR, has a repeater relay BTHSPR which is, energized over an obvious circuit including back contact 20 of relay BTHR and front contact 2| of relay BTHSR. Relay BTHSPR, when picked up opens its back contact 22 in the preme-ntioned pick up circuit of relay BTER, and as will be made clear presently has the function of positively assuring operation of the crossing signals when a train enters section CT after operation of the signals has been discontinued as a result of the train slowing down or stopping in section BT, or after the train enters section ET over track switch SW.

The windings l of the interlocking relays, the speed measuring relays TER for the timing sections, and the time element relays THR with the associated stick relay THSR, or the repeater relay THSPR, cooperate with relay XTR of the crossing section XT in the control of operating relay OR to provide substantially uniform periods of operation of the crossing signal for trains operating at different speeds approaching the crossing, while providing for the discontinuance of the operation if a train should stop or slow down in sections B1 or CT, the avoidance of setting into operation the crossing signals if a train should enter section ST or CT from a siding and recede from the crossing, and the establishment of directional control arranged to prevent operation of the signals when the train recedes from the crossing. This control of the signals is established by providing operating relay OR with a circuit controlled by the various elements named above, and effective when all of the various sections are vacant, to energize relay OR over a normal circuit path including, in series, flagman contacts l3 of winding i of interlocking relays BXR, CXB and DXR, and front contact l6 of relay XTR, At times front contact as of relay ATER is closed to provide an alternate path around flagman contact l3 of winding 4 of relay BXR in the normal circuit path just traced, and at other times front contact 23 of relay BTHSPR closes another alternate path around fiagman contact I3 of relay BXR. Similarly front contact 33 of relay BTER at times provides an alternate path around flagman contact 53 of winding 4 of relay CXR in the normal circuit path of operating relay OR, while at other times another alternate path around flagman contact 13 of relay CXR is provided through back. contact 29 of relay CTHR and front contact 3% of relay CTHSR. Relay OR when released closes its back contact ll to establish an obvious energizing circuit for the crossing signals XS.

The lengths of the operating sections will be so selected that a train operating at the maximum train speed for the stretch will require approximately 20 seconds to reach the intersection after entering the first operating section which it encounters, while trains operating at one or another of a plurality of ranges of slower speeds will require approximately 20 seconds to reach the crossing after entering one or another of the succeeding operating sections selected according to the train speed. For example, with the arrangement of sections shown in the drawing and assuming that the maximum authorized train speed is 80 miles per hour, and that a medium speed ranges between 45 miles per hour and 15 miles per hour, while a slow speed range includes speeds of 15 miles per hour or less, the combined lengths of the operating sections BT, CT and DT will be such that a train operating at the maximum speed of 80 miles per hour will require approximately 20 seconds to reach the intersection after entering section ET, the combined lengths of sections CT and DT will be such that a train travelling at the highest authorized medium speed (45 miles per hour) will require 20 seconds to reach the intersection after entering section CT, while the length of section DT will be such that a train travelling at the highest speed (15 miles per hour) in the slow speed range will require 20 seconds to reach the intersection after entering section DT. As will be explained hereinafter, a train travelling toward the intersection at more than medium speed will set the signals into operation when it enters section BT, while a train travelling at medium speed will set the signals into operation when it enters section CT, and a train travelling at slow speed will set the signals into operation when it enters sec tion DT. The apportionment of the various track sections referred to above will therefore insure an operating period of at least twenty seconds before a train arrives at the intersection. Section XT is symmetrically arranged with respect to the intersection, and preferably just spans the crossing so that it is relatively short with respect to the lengths of sections 131, CT and DT.

It will be understood that the operating cycles of the time element relays TER will be adjusted with respect to the length of the associated measuring sections so that each time relay will operate through its complete cycle within the time required for a train operating within a speed range selected for that section, to traverse the section. Sections AT and BT are medium speed and slow speed measuring sections, respectively, and relay BTER will thus be adjusted with respect to the length of section ET so as to pick up within the time required for a slow speed train (operating at 15 miles per hour) to traverse section BT, while relay ATE-R will be adjusted with respect to the length of section AT so as to pick up within the time required for a medium speed train (operating at 45 miles per hour) to traverse section AT. Section AT can therefore be of any suitable length and its length will largely be determined by the ranges of operating periods afforded by the particular form of timing relay employed.

It should also be understood that the operating cycles for the time element relays THR provided for certain of the operating sections will likewise be adjusted with respect to the length of the associated section so that each relay THE will pick up if the associated section is occupied by a train for longer than a predetermined period.

The apparatus embodying my invention is i1- lustrated in the drawing in the normal condition that it obtains when the track sections are unoccupied. In this condition of the apparatus each track relay is picked up and both windings of each interlocking relay are energized. Relay OR is energized over its previously traced normal circuit and the signals are disconnected from the source of power. The time element relays TER, thermal relays THR, stick relays THSR and repeater relay TI-ISPR are all released.

I shall now describe the operation of my invention and shall for that purpose first assume that an eastbound train travelling toward the intersection enters section AT at more than medium speed and maintains that speed at least until it reaches the intersection. Upon entering section AT the train shunts track relay ATR causing it to release and its back contact Ill closes to complete an operating circuit for time element relay ATER, which circuit extends from terminal B over front contact H of relay BTR and back contact 10 of relay ATR through relay ATER to terminal N. As previously pointed out, relay ATE' U has an operating cycle such that it will pick up only after being energized for a predetermined period which is equal to that required for a train to travel the length of section AT at medium speed, and since the train being considered is travelling at more than medium speed, relay ATER, will not pick up before the train travels the length of section AT and enters section BT.

When the train enters section BT, track relay BTR releases and its front contact ll opens the circuit for relay ATER to discontinue the energizaticn of relay ATER and so prevent it from picking up under these conditions. Back contact ll of relay BTR closes, but its closing performs no useful function at this time. Front contact 12 of relay BTR opens the obvious energizing circuit for winding 4 of interlocking relay BXR and that winding releases so that its flagman contact l3 opens. This causes the re lease of relay OR, by opening its normal energizing 1 circuit including i'lagman contacts [3 of each of the windings 4 of the interlocking relays XR and front contact [6 of relay XTR. Back contact ll of relay OR closes the obvious circuit for the signals KS and the signals begin their operation. It will thus be seen that the signals are set into operation when a train enters section BT at a speed above the medium speed.

When relay BTR releases, its back contact l2 closes to complete the operating circuit for relay BTHR which circuit also includes back contact N3 of relay BTHSR. Relay BTHR has as previously mentioned an operating cycle such that it will pick up only after being energized for a period substantially longer than that required for a train moving at any substantial speed to travel the length of section BT. Relay BTHR therefore will not pick up before the train travels the length of section BT and enters section CT, and further operation of relay BTHR need be considered only in the event that the train slows down or stops in section ET. This operation will be discussed in detail hereafter.

When back contact H of relay BTR is closed it also brings about the energization of relay BTER by completing its operating circuit extending from terminal B over back contact l2 of relay BTR, back contact 22 of relay BTHSPR and front contact 24 of relay CTR through relay BTER to terminal N. As previously pointed out, the operating cycle for relay BTER is such that it will pick up only after being energized for a predetermined period which is equal to that required for a train moving at slow speed to travel the length of section BT, and since the train is travelling at more than medium speed relay BTER will not pick up before the train travels the length of section BT and enters section CT.

As the train enters section CT track relay CTR releases opening its front contact 2 2 This opens the previously traced operating circuit for relay BTER to discontinue the energization of relay BTER and so prevent it from picking up under the conditions assumed. Front contact 25 of relay CTR also opens to open the obvious energizing circuits for winding of interlocking relay BXR, which releases to its latched up position, and winding i of relay CXR. Flagman contact it of winding d of relay CXR becomes opened in the previously traced normal energizing circuit for relay OR. Relay OR is held released and its back contact ll remains closed to maintain the signals in operation.

Back contact 25 of relay CTR closes to complete the operating circuit for relay CTHR which circuit extends from terminal B over back contact 26 of relay CTR and back contact 2] of relay CTHSRA through relay CTHR to terminal N. Relay CTHR has an operating cycle which as previously mentioned is such that it will pick up only after being energized for a period substantially longer than that required for a train moving at any substantial speed to travel the length of section CT. Relay C'IHR therefore, will not pick up before the train travels the length of section CT and enters section DT and like relay BTHR, further operation of relay CTHR will be of importance to the system only if the train slows down or stops in section CT and will be discussed hereinafter.

W'hen the train enters section DT relay DTR releases opening its front contact 3! in the obvious energizing circuit for winding 4 of relay DXR. Winding a releases and opens its front contact E3 in the previously traced normal energizing circuit for relay OR. When front contact 3! of relay DTR opens it also brings about the deenergization of winding 5 of relay CXR by opening its previously traced circuit and winding 5 releases its armature to the latched up position.

When the train enters section XT relay XTR releases opening front contact It in the normal energizing circuit for relay OR thus maintaining relay OR released and its back contact ll closed to insure operation of the signals while the train occupies that section. Front contact 32 or relay XTR also opens when relay XTR rethe effect of which is to bring about the deenergization of winding 5 of relay DXR by opening its energizing circuit which extends from terminal 3 over front contact 32 of relay XTR through winding 5 to terminal N. Winding 5 releases and its armature drops to the latched up position.

the train vacates section AT relay ATR picks up to open its back contact It in the previoi ly traced operating circuit for relay A'IER. l: v circuit for relay ATER is however, already open at front contact H of relay ETR as expl ed heretofore, and the opening of back contact it of relay ATR therefore has no effect upon relay ATER.

When the train vacates section BT, relay BTR picks up, its back contact ll opens and its front contact ll closes. Back contact 12 of relay BTR also opens as the train vacates section ET. This contact is in the circuit for relay BTER- but that circuit is already open at front contact 25 of relay CTR as the latter contact opened when the train entered section CT. Front contact E2 of relay BTR closes to complete the previously traced energizing circuit for winding l of relay BXR and winding 4 picks up: to close its fiagman contact It in the normal energizing circuit for relay OR. This circuit, however, is still open at fiagman contacts I3 of windings t of relays CXR and DXR and at front contact l6 of relay XTR. Relay OR- is therefore held released and its back contact I! remains closed to continue operation of the signals.

As the train vacates section CT relay CTR picks up and its front contact 24 closes to prepare the energizing circuit for relay BTER but that relay is unaffected because its circuit remains open at back contact 12 of relay BTR. Front contact 25 of relay CTR closes to complete the previously traced energizing circuit for winding 5 of relay BXRand winding 5 picks up. Front contact 25 also completes the previously traced energizing circuit for winding l of relay CXR and that winding picks up to close its flagman contact [-3 in the normal energizing circuit for relay OR. Although flagman contacts E3 of windings l of relays BXR and CXR are closed in this circuit, it is still open at flagman contact it of winding 4 of relay DXR and front contact it of relay X'IR. Relay 0R therefore remains deenergized and its back contact ll remains closed to continue operation of the signals.

When the train vacates section DT relay DTR picks up closing its front contact 3| to complete the previously traced energizing circuit for winding 4 of relay DXR. Winding '6 now picks up closing its flagman contact 13. Although the normal energizing circuit for relay OR extends over this fiagman contact relay OR remains released and the signals continue to operate since the energizing circuit for relay OR is still open at front contact it of relay XTR. When front contact 3| of relay DTR closes it also completes the previously traced energizing circuit for wind ing 5 of relay CXR and that winding 5 picks up.

After the train vacates section XT, relay XTR picks up to close its front contact 16. The normal energizing circuit for relay OR is now complete at flagman contacts l3 of windings l of relays BXR, OXR and DXR and front contact It of relay XTR. Relay OR accordingly picks up opening its back contact H, the signals XS cease their operation, and the apparatus is restored to its normal condition.

I shall now assume that .an eastbound train travels toward the intersection at medium speed, which it maintains at least until it reaches the intersection. When this train enters section AT relay ATR releases and its back contact It closes to complete the previously traced circuit for time element relay ATER. Relay ATER will pick up after being energized for a period equal to that required for a train to travel the length of section. AT at the highest speed (45 miles per hour) in the medium speed range and since the train being considered is moving at a speed in this range relay ATER will pick up before the train travels the length of section AT and enters section BT. When relay ATER picks up its front contact 33 closes to prepare a stick circuit for relay ATE'R and its front contact 36 closes to complete an alternate circuit path about flagma contact it of winding 4 of relay BXR in the normal energizing circuit for relay OR.

When the train enters section BT, track relay BTR releases and its front contact ll opens the previously traced operating circuit for relay ATER, momentarily disconnecting it from the source of power. Before relay ATER can release however, back contact ll of relay BTR closes to establish a stick circuit for relay ATER over its from contact 33 and relay ATER is held energized.

Front contact l2 of relay BTR opens the previously traced energizing circuit for winding 4 of interlocking relay BXR and winding 4 releases to open its front contact l3. Although the normal energizing circuit for relay OR extends over flagman contact l3 of winding 4, relay OR is unaffected when this contact opens because of the alternate path established about contact l3 when front contact 34 of relay ATER closes. Relay OR is therefore held energized and its back contact [1 remains open to prevent the signals from operating.

Back contact l2 of relay BTR closes to com plete the operating circuit for relay BTHR but as previously explained operation of relay BTHR at this time need not be considered.

When back contact (2 of relay BTR closes it also brings about the energization of relay BTER by completing the previously traced circuit of that relay. As already explained the operating cycle of relay BTER is such that it will pick up only after being energized for a predetermined period which is equal to that required for a train moving at slow speed to travel the length of section BT, and since this train is travelling at more than slow speed relay BTER will not pick up before the train travels the length of section BT and enters section CT.

As the train enters section CT relay CTR releases opening its front contact 24. Front contact 24 opens the operating circuit of relay BTER to discontinue the energization of relay BTER and thereby prevent it from picking up. Front contact 25 of relay CTR opens the energizing circuit for winding 4 of interlocking relay CXR and as a result its flagman contact l3 opens in the previously traced energizing circuit for relay OR. Relay OR releases to close its back contact H thereby setting the signals into operation. It will be seen therefore that the signals are set into operation when a medium speed train enters section CT.

When front contact 25 of relay CTR opens it also brings about the deenergization of wind- 1 ing 5 of relay BXR by opening the previously traced energizing circuit for that relay. Winding 5 releases and its armature drops to a latched up position. Back contact 25 of relay CTR closes to complete the operating circuit for relay CTHR, but this action need not be considered at this time.

The operations which follow as the train enters sections DT and KT are the same as those already described for an eastbound train travelling toward the intersection at more than medium speed and a detailed description at this point is therefore believed unnecessary.

As the train vacates section AT relay ATR picks up to open its back contact It in the pre-- viously traced circuit for relay ATER. This relay is however now held energized over its stick circuit including back contact ll of relay BTR as explained heretofore and relay ATER is therefore unaffected.

When the train vacates section BT relay BTR picks up and its back contact ll opens the previously traced stick circuit for relay ATER, whereupon relay ATER releases to open its front contacts 33 and 34. Relay OR is unaffected when front contact 34 of relay ATER opens since the energizing circuit for relay OR is now open at flagman contact l3 of winding 4 of relay CXR and DXR and at front contact N5 of relay XTR to insure the deenergization of relay OR and the continued operation of the signals. With the exception of the release of relay ATER previously described, the operation of the apparatus in response to the medium speed train vacating sections BT, CT, DT and XT is identical to that previously described for the high speed train and repeated explanation is believed unnecessary, it being obvious that operation of the crossing signals is maintained until the train clears section XT at which time the apparatus is restored to normal.

When a train travelling toward the intersection at slow speed enters section AT it shunts track relay ATR causing it to release and its back contact Ill closes to complete the operating circuit of time element relay ATER. Since relay ATER will pick up after being energized for a period equal to that required for a train to travel the length of section AT at medium speed and the train being considered is moving at less than medium speed, relay ATER will pick up before the train travels the length of section AT and enters section BT. When relay ATER picks up its front contact 33 closes to prepare a stick circuit for relay ATER and its front contact 34 closes to complete an alternate path about front contact IQ of winding 4 in the normal energizing circuit for relay OR.

When the train enters section BT, track relay BTR releases and its back contact ll closes to establish the stick circuit for relay ATER as previously explained.

Front contact !2 of relay BTR also opens to deenergize winding 4 of interlocking relay BXR and winding 4 releases to open its flagman contact 13, but this action as previously mentioned does not result in releasing relay OR because of the alternate path established about this flagman contact I3 when front contact 34 of relay ATER is closed. Relay OR is therefore held energized and its back contact l1 remains open to prevent the signals from operating.

With back contact l2 of relay BTR closed relay BTER is now energized. As already explained the operating cycle of relay BTER is such that it will pick up after being energized for a predetermined time which is equal to that required for a train moving at the highest speed (15 miles per hour) in the slow speed range to travel the length of section BT, and since this train is travelling at a speed in this range relay BTER will pick up before the train travels the length of section BT and enters section CT. When relay BTER picks up its front contact 35 closes to prepare a stick circuit for relay BTER and its front contact 36 closes to complete an alternate path about flagman contact I3 of winding 4 of relay CXR in the normal energizing circuit for relay OR.

When the train enters section CT track relay CTR releases and its front contact 24 opens the previously traced operating circuit for relay BTER momentarily disconnectin it from the source of power. Before relay BTER can release however, back contact 25 of relay CTR closes to establish a stick circuit for relay BTER over its 13 front contact 35 and relay B'IER is held energized.

Front contact 25 of relay CTR opens the obvious energizing circuits for windin 5 of interlocking relay Elm, which releases to its latched up position, and for winding 4 of relay CXR, which opens its flagman contact I3 in the previously traced normal energizin circuit for relay OR. Relay OR is unaffected when fiagman contact l3 opens because of the alternate path established about this fiagman contact l3 when front contact 36 of relay BTER is closed. Relay OR is therefore held energized and its back contact ll remains open to prevent the signals from operating.

When this slow speed train enters section DT, relay DTR releases to deenergize both windings 5 of relay CXR and winding 5 of relay BER, and the latter opens its fiagman contact [3 to open the circuit for relay OR and set the crossing signals into operation. It follows therefore, that for a slow speed train operation of the signals will be initiated only when the train enters operating section DT.

The operations which follow as the train enters section XT are the same as those already described for a train travelling toward the intersection at more than medium speed and a detailed description at this point is therefore believed unnecessary. Also, the operations of the system when the slow speed train vacates the several sections will be the same as those already described, it being noted that relay ATER will release when the train vacates section BT and relay BTER will likewise release when section CT is vacated. Operation of the crossing signals will be maintained unti1 section X'I' is cleared by the train and at that time the apparatus will be restored to normal.

Having described the manner in which the signals are set into operation when a train approaching the intersection arrives at one or another of a plurality of points in the approach stretch of track depending upon the speed of the train, and are thereafter maintained in operation until the train vacates the crossing section, I shall now describe the manner in which my invention functions to interrupt the operation of the signals when a train which has caused the signals to be set into operation stops or unduly delays in either section BT or CT.

In considering. this function of my system in connection with a train that slows down or stops in, section ET, it is of course necessary to treat only a high speed train which stops or slows down in section ET because the signals will have been set into operation. by this train when it entered section BT, whereas medium and slow speed trains do not initiate the operation of the signals when section ET is entered. I shall therefore assume first that an eastbound train travelling at more than medium speed stops or unduly delays in section BT. As explained previously, a train travelling at more than medium speed will when it enters section BT cause front contact 13.

of winding 4 of relay BXR to open the normal energizing circuit for relay OR and the signals will be set into operation. Under the conditions assumed, timing relay BTHR is brought into operation and the manner in which it functions to affect the control of operating relay OR will now be explained. With the train stopped or unduly delayed in section BT, back contact l2 of relay BTR completes the energizing circuit of relav BTl-IR for the operatin period of that relay, and relay'BTHR will pick up to close its front contact l9, thereby completing the pick up circuit for relay BTHSR. The latter relay in turn picks up to close its front contact is and complete its stick circuit, and to deenergize relay BTHR at back contact I 8. When relay BTHR releases, relay BTHSPR is energized over back contact 20 of relay BTI-IR and front contact 2! of relay BTHSR, and relay BTHSPR thereupon picks up to close its front contact 23 which completes an alternate path around opened flagman contact I3 of relay BXR in the circuit of relay OR. Relay OR is therefore energized and picks up to discontinue the operation of the crossing signals. Relay BTl-ISPR also opens its back contact 22 in the operatin circuit of relay BTER and in that way prevents the continued occupancy of section BT by the train (before it enters section CT) from causing relay BTER to be picked up when the train enters section CT. As a result therefore, when the train in section BT resumes its movement toward the intersection, the release of relay CTR when. the train enters section CT will result in winding 4 of relay CXR openin its flagman contact 13 to again deenergize relay OR and restart the operation of the CIOSSlllg signals. Further operation of the system for this train will be similar to that already described in detail, it being noted that when section ET is vacated, relay BTR in picking up opens at its back contact I? the stick circuit of relay BTHSR so that the latter relay will release and in turn cause its repeater relay BIHSPR to release.

In considering this function of my system for a train stopping in section CT, it is of course unnecessary to consider slow speed trains because for these trains the signals are set into operation only when section D1 is entered. I shall therefore assume that the stretch is entered by a train travelling at a speed above the low speed range, and that this train stops or unduly delays in section CT. If this train entered the stretch at high speed, the signals will have been set into operation when the train entered section BT, and are retained in operation after it clears that section and occupies section CT because at that time fiagman contact l3 of relay CXR is open in the energizing circuit of relay OR so that relay OR is released and the signals are operating, On the other hand, if the train entered the stretch at medium speed, operation of the signals will have been initiated when the train entered section CT. In either event, if the train stops or unduly delays in section CT, relay CTHR is brought into operation and is energized, for the length of its operating cycle, over back contacts 26 and 2'? of relays CTR and CTHSR. Relay CTHR will pick up to close its front contact 28, whereupon relay CTHSR picks up to close its stick contact 27 and deenergize relay CTHR. When the latter relay releases, an alternate circuit path is established around opened flagman contact 13 of relay CXR. and relay OR becomes energized over a circuit ineluding flagman contact [3 of winding i of relay BXR (or front contact 3 5 of relay ATER in the case of a medium speed train stopping in section CT without clearing section BT), back contact 29 of relay CTHR, front contact 38 of relay CTHSR, iiagman contact it of winding 4 of relay DXR, and front contact [6 of relay XTR. Relay OR will therefore pick up and discontinue the operation of the crossing signals.

When the train resumes its movement and enters section DT, it causes release of winding 4 of relay DXR and flagman contact I3 of that winding opens. The alternate energizing circu t previously traced for relay OR including back contact 29 of relay CTHR, and front contact 39 of relay CTHSR is now open at fiagnian contact I3 of relay DXR and relay OR releases to again set the signals into operation.

The remaining operations which occur as the train enters sections UT and XT, and as the train vacates each of the various track sections employed have been considered elsewhere and it is, believed unnecessary to repeat them here except to point out that when the train vacates section CT, the stick circuit of relay CTHSR is opened and relay CTHSR releases when relay CTR- picks up.

My invention also provides for a proper period of operation of the highway crossing signal in the event a train should engage in switching movements at one of the sidings located in the approach stretch of track.

If a train is to enter section BT from a siding, the track switch BW is set accordingly and its contact l' becomes closed. When this train enters section BT relay BTR releases closing its back contact :2 thereby completing an alternate circuit for relay BTHSR, which circuit extends from terminal B over back contact IQ of relay BTR and contact I of switch BW through the winding of relay BTHSR to terminal N. Relay BTHSR picks up and its front contact it closes to complete the previously traced stick circuit for relay BTHSR, which removes contact I of the track switch from control of relay BTHSR. Front contact 25 of relay BTHSR closes to complete the previously traced energizin circuit for relay BTHSPR and relay BTHSPR picks up to open its back contact 22 and to close its front contact 23. Back contact 22 of relay BTl-ISPR opens the previously traced operating circuit for relay BTER to prevent relay BTER from picking up due to the occupancy of section BT with section CT vacant, and front contact 23 of relay BTHSPR establishes an alternate circuit path about front contact i3 of winding ll,

When the train entered section BT and relay BTR released, its front contact I2 opened the energizing circuit for winding i of relay BXR. Winding 4 released and opened its front contact t in the normal energizing circuit for relay OR, but the latter is retained energized because of the alternate path established by contact 23 of relay BTHSPR about flagman contact I3 of relay BXR when the train entered section BT over switch BW reversed, as explained above. This alternate path maintains relay OR energized to prevent the signals from operating under the 1 "ions assumed.

11 the train should clear the switch BW and the track switch BW be returned to its normal position while the train is still in section BT, relay BTi-ISR will nevertheless remain energized because of the stick circuit established over ts front contact I8. Relay BTHSPR w ll rema n picked up and its front contact 23 will remain closed to maintain the alternate path about front contact I3 of winding intact. Relay OR w ll therefore be held energized and the signals will w ented from operating.

f i fiis l lfmll'lg the train proceeds toward the intersection, when it enters section CT relay CTR releases and its front contact 25 opens the energizing circuit for winding 4 of relay CXR. W1nding 4 releases and its fiagman contact I3 opens to disconnect relay OR from the source of power.

Relay OR releases and its back contact I'I closes to set the signals into operation.

The other operations which occur as the train proceeds in the assumed direction are the same as those dealt with elsewhere and it is believed unnecessary to relate them again here.

If the train should recede from the crossing instead of travelling toward it, it will enter section AT and cause the release of relay ATR. Back contact II] of relay ATR will close to prepare the pick up circuit of relay ATER, which circuit is now held open at front contact II of relay BTR.

When the train vacates section BT, relay BTR picks up and back contact I2 opens the previously traced stick circuit for relay BTHSR. Relay BTHSR releases and its front contacts I8 and 2| open, the latter interrupting the circuit for relay BTHSPR and relay BTHSPR releases to close its back contact 22 and to open its front contact 23. Front contact 23 opens the alternate path about front contact I3 of winding 4 but relay OR does not release, for when relay BTR picks up its front contact I2 closes the previously traced energizing circuit for winding 4 of relay BXR and that winding picks up closing its flagman contact It to complete the normal energizing circuit for relay OR. In this manner relay OR is held energized and the signals are prevented from operating.

When section ET is vacated, the previously traced operating circuit for relay ATER is now closed at front contact I I of relay BTR and relay ATER may pick up. If relay ATER does pick up, its front contacts 33 and 34 will close but neither will perform a useful function at this time. When the train vacates section AT, relay ATR picks up opening its front contact I0, and. if relay ATER has picked up it releases to open its front contacts 33 and 34 thereby restoring the apparatus to its normal condition.

I shall now assume that a train is about to enter section CT from a siding and that track switch CW is set for traffic between the main line and the siding so that contact I of switch SW is closed. When the train enters section CT over switch CW, relay CTR releases closing its back contact 26 thereby completing an alternate circuit for relay CTHSR, which circuit extends from terminal B over back contact 26 of relay CTR and contact I of switch SW through the winding of relay CTHSR to terminal N. Relay CTI-ISR picks up and its front contact 21 closes to complete the previously mentioned stick circuit for relay CTHSR which removes contact 1 of switch CW from control of relay CTHSR. Front contact 30 of relay CTHSR closes to establish an alternate path about flagman contact I3 of winding 4 of relay CXR in the circuit of relay 0R.

When the train entered section CT and relay CTR released, its front contact 25 opened the energizing circuits for winding 5 of relay BXR, and for winding 4 of relay CXR. The latter winding opened its contact I3 to open the normal energizing circuit for relay OR, but relay OR is maintained energized because of the alternate path established about contact I3 of relay CXR when the train entered section CT as explained above. This prevents the signals from operating.

If the train should clear switch CW and the track switch CW be returned to its normal position while the train occupies section CT, relay CTHSR will nevertheless remain energized because of the stick circuit established over its front contact 21,-andwill hold closed its front contact. 30 tomaintain thealternate path about flagman contact 13 of winding of relay CXR so that relay OR will therefore remainenergized and thesignals will be prevented from operating.

Assuming the train proceeds toward the intersection, when it enters section DT relay DTR releases and its front contact-3| opens the energizing circuit for winding 4 of relay- Dim. Winding 4 releases and its flagman contact 13 opens to disconnect relay OR from the source of power. Relay OR releases, its back contact I! closes and the signals begin to operate.

The remaining operations which occur as the train enters sections DT and KT, and as it vacates each of the various track sections employed have already been considered in detail and it is believed unnecessary to repeat them at this point.

If the train should recede from the crossing instead of travelling toward it the system will operate to provide a directional control of the crossing signals effective to prevent operation with the train in sections BT and AT, in the same manner asthat which will be described hereinafter for-awestbound train movement. At this time it is only necessaryto point out that the stick circuit which holds relay CTHSR energized will be opened when section CT is vacated, so that relay CTHSR will then release.

Considering now'the operation of the system for a westbound train movement, it will of course be understood-that the stretch of track (not shown) on the other side ofthe crossing will be provided with apparatus for controlling the operation of'the'crossing signals when westbound trains approach the intersection but since a consideration of such apparatus isnot required for an understanding of my-invention, the apparatus providing such a control has not been illustrated in the drawing and will notbe further discussed in the description except to point out that such apparatus may control an operating relay similar to relay OR, in which case relay XTR can be used (as in the case of eastbound movement) to assure release of the operating relay for westboundtrains during occupancy of the crossing "section XT. Assuming now that a westbound train operates on the stretch, I shall describe how the apparatus illustrated 'in 'the drawing functions 'for such westbound train. Relay XTR at the crossing will of course be shunted when the train reaches the intersection and this relay will'hold open its front contact IE to deenergize relay .OR and maintain the operation of the crossing signals until the train clears the crossing section. Front contact'32 of relay XTR also is open under these conditions and as a result winding 5 of relay DIG, is released to its full-down position.

When the train enters section'DT relay'DTR releases and its front contact 3| opens the energizing circuits for winding 4 of interlocking relay DXR and winding 5 of relay CXR. Winding '4 of relay DXR releases but its flagman contact I3 remains closed since winding 5 of interlocking relay DXR has already been released as noted above and the armature of the other winding of this relay may now drop to a'latched up position only. With the energizing circuit for winding'5 of relay CXR now open, that winding drops to its full-down position.

As the trainenterssection CT relay CTR releases and its front -contact'25 opens-the energizing circuit for-winding 4 ofrelay CXR-causing that wlnding to release. Flagman contact .18 13 of winding 4 remains closed, however, since winding 5 of interlocking relay CXR has already een released and the armature of winding 4 may now drop to a latched up position only. Front contact 25 of relay CTR also opens the energizing circuit for winding 5 of relay BXR and winding 5 releases.

When the train enters section BT relay BTR releases and its front contact i2 opens the energizing circuit for winding 4 of relay BXR. Although winding 4 releases, its fiagman contact I3 remains closed since its armature is latched up by the prior release of winding 5 of that relay.

It is apparent from the foregoing that the normal energizing circuit for relay OR remains closed at fiagman contacts [3 of windings l of relays BXR, CXR and DXR. as the train recedes from the crossing. It only remains for front contact 16 of relayXTR to close to complete the normal energizing circuit for relay OR and this occurs when the train vacates section XT causing relay XTR to pick up. Thus, the signals become inactive when the train vacates section XT and remain so as the train continues to recede from the crossing.

When the westbound train vacates sections DT, CT and ET, the track relays for each section will pick up to energize the windings of the interlocking relays which it controls and when section AT is vacated relay ATR will pick up so that all of the apparatus is restored to its normal condition as illustrated in the drawing.

It follows from the foregoing description of the operation of the apparatus shown in the drawing, that a highway crossing signal control system embodying my invention is effective to provide reasonable periods of operationof a highway crossing signal in a variety of possible situations, that is, periods of operation which while adequate to warn users of the highway of an approaching train are not excessive so as to cause. an undue delay of highway traffic.

Prolonged periods of operation by trains travelling at a relatively slow speed are prevented and a substantially uniform period of operation regardless of the speed with which a train approachesthe intersection is provided in its place. Stops and undue delays in the approach stretch of track are also accommodated without excessive periods of operation of the signalslby interrupting their operation until thetrain can once again resume its movementtoward the crossing. If a train should enter the approach stretch of track from a siding or engage in switching movements at the'siding, it will not cause the. signals to be set into operation until it advances far enough toward the crossing to enter an adjoining control'section, and a train receding from the crossing on a single track stretch may proceed without actuating the-signals at all.

It is to be noted that my invention provides means operative when the crossing signalshave been cut out by a train delaying or stopping in a section used both as an operating and a measuring-section, to remove the measuring apparatus of that section from control of the crossing signals so that'the signals will be set into operation immediately when the train resumes its operation towardthe crossing and enters the next adjacent section toward the intersection. This feature is provided for section ET by relay BTHSPR which repeats relay BTHSR and when picked up opens the pick up circuit oftime measuring relay 'BTER associated'with-section BT. In this manner operation of the signals willbe resumed.

19 for a high speed train when it enters section CT if that train slows down or stops in section BT to cause the thermal time element relay BTHR to operate and discontinue the signal operation.

Although I have illustrated and described only one form of highway crossing signal control system embodying the features of 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 control system for a highway crossing signal located at the intersection of a highway and a stretch of railway track provided with a plurality of successive adjoining approach sections located to one side of and adjoining a crossing section including the intersection, the combination with said highway crossing signal and said track sections of a timing relay for the one of said track sections most remote from said intersection, means for operating said timing relay when the associated section is occupied provided the next adjacent section is vacant, an interlocking relay for each of the remaining approach sections and each having a first winding responsive to traiilc in the associated section and a second winding responsive to trafiic in the next adjoining section toward the intersection, an operating relay for controlling the operation of said highway crossing signal, a circuit including in series a contact of each first winding of the interlocking relays for normally energizing said operating relay, and means controlled by said timing relay for at times completing an alternate path in said circuit for said operating relay around the contact of the interlocking relay for the section next adacent said most remote section.

2. In a control system for a highway crossing signal located at the intersection of a highway with a stretch of railway track provided with a plurality of successive adjoining approach sections located to one side of and adjoining a crossing section including the intersection, the combination with said highway crossing signal and said track sections of a plurality of interlocking relays one for each of said approach sections except the section most remote from the intersection and each having a first winding responsive to traffic in the associated section and a second winding responsive to trafiic in the next adjoining section toward the intersection, a plurality of timing relays one for each of a plurality of said approach sections including said most remote section and at least the next adjacent section, means for operating each said timing relay when its associated section is occupied provided the next adjacent section toward the crossing is vacant, an operating relay for controlling the operation of said highway crossing signal, a circuit including in series a contact of each first winding of the interlocking relays for normally energizing said operating relay, and means controlled by each said timing relay for at times completing an alternate path in said circuit for said operating relay around the contact of the interlocking relay for the section next adjacent the section associated with that timing relay.

3. In a control system for a highway crossing signal located at the intersection of a highway with a stretch of railway track provided with a plurality of successive adjoining approach sections located to one side of and adjoining a crossing section including the intersection, the combination with said highway crossing signal and said track sections of a plurality of interlocking relays one for each of said approach sections except the section most remote from the intersection and each having a first winding responsive to trafllc in the associated section and a second winding responsive to trafiic in the next adjoining section toward the intersection, a plurality of timing relays one for each of a plurality of said approach sections including said most remote section and at least the next adjacent section, means for operating each said timing relay when its associated section is occupied provided the next adjacent section toward the crossing is vacant, another timing relay for the one of said track sections adjacent the most remote section, means for operating said other. timing relay when its associated section is occupied, an operating relay for controlling the operation of said highway crossing signal, a circuit including in series a contact of each first winding of the interlocking relays for normally energizing said operating relay, means controlled by each of said plurality of timing relays for at times completing an alternate path in said circuit for said operating relay around the contact of the interlocking relay for the section next adjacent the section associated with that timing relay, and means controlled by said other timing relay for at times completing an alternate path in said circuit for said operating relay around the contact of the interlocking relay of the section associated with said other timing relay.

4. In a control system for a highway crossing signal located at the intersection of a highway with a stretch of railway track provided with a plurality of successive adjoining approach sections located to one side of and adjoining a crossing section including the intersection, each said track section being provided with a track circuit including a track relay, the combination with said highway crossing signal and said track relays of a plurality of interlocking relays one for each of said approach sections except the section most remote from the intersection and each having a first winding controlled by the track relay of the associated section and a second winding controlled by the track relay of the next adjoining section toward the intersection, a plurality of timing relays one for each of a plurality of said approach sections including said most remote section and at least the next adjacent section, means controlled by said track relays for operating each said timing relay when its associated section is occupied provided the next adjacent section toward the crossing is vacant, another timing relay. for the one of said track sections adjacent the most remote section, means controlled by said track relays for operating said another timing relay when its associated section is occupied, an operating relay for controlling the operation of said highway crossing signal, a circuit including in series a contact of each first winding of the interlocking relays for normally energizing said operating relay, means. controlled by each of said plurality of timing relays for at times completing an alternate path in said circuit for said operating relay around the contact of the interlocking relay, for the section next adjacent the section associated with. that timing relay, and means controlled by said other timing relay for at times completing an; alternate path in said circuit for said'operating relay around the contact of the interlocking;

relay of the section associated with said' other timing relay and for disconnecting the timing relay of the one of said sections adjacent said most remote section from its operating means.

5. In a control system for a highway crossing signal located at the intersection of a highway with a stretch of railway track provided with a plurality of successive adjoining approach sections located to one side of and adjoining a crossing section including the intersection, the combination with said highway crossing signal and said track sections of a plurality of interlocking relays one for each of said approach sections except the section most remote from the intersection and each having a first winding responsive to traffic in the associated section and a second winding responsive to trafiic in the next adjoining section toward the'interse'ction, a plurality of timing relays one for each of a plurality of said approach sections including said most remote section and at least the next adjacent section, means for operating each said timing relay when its associated section is occupied provided the next adjoining section toward the crossing is vacant, two additional timing relays one for the said adjacent section and one for the next succeeding section toward the intersection, means for operating each said additional timing relay when its associated section is occupied, an operating relay for controlling the operation of said highway crossing signal, a circuit including in series a contact of each first winding of the interlocking relays for normally energizing said operating relay, means controlled by each of said plurality of timing relays for at times completing an alternate path in said circuit for said operating relay around the contact of the interlocking relay for the next section adjoining the section associated with that timing relay, means controlled by the additional timing relay of said adjacent section for at times completing an alternate path in said circuit for said operating relay around the contact of the interlocking relay of said adjacent section and for disconnecting the timing relay of said adjacent section from its operating means, and other means controlled by the additional timing relay of said next succeeding section for at times completing an alternate path in said circuit for said operating relay around the contact of the interlocking relay of said next succeeding section.

6. In a control system for a highway crossing signal located at the intersection of a highway with a stretch of railway track provided with a plurality of successive adjoining approach sections located to one side of and adjoining a crossing section including the intersection, a track switch for the section next adjacent the section most remote from said intersection, the combination with the foregoing of a plurality of interlocking relays one for each of said approach sections except said most remote section and each having a first winding responsive to trafiic in the associated section and a second winding responsive to traffic in the next adjoining section toward the intersection, a plurality of timing relays one for each of a plurality of said approach sections including said most remote section and at least the said adjacent section including said track switch, means for operating each said timing relay when its associated section is occupied provided the next adjoining section toward the crossing is vacant, another timing relay for said adjacent track section,

means for operating said other timing relay when said adjacent section is occupied, an oper ating relay for controlling the operation of said highway crossing signal, a circuit including in series a contact of each first winding of the interlocking relays for normally energizing said operating relay, means controlled by each of said plurality of timing relays for at times completing an alternate path in said circuit for said operating relay around the contact of the interlocking relay for the next adjoining section toward the intersection from the section associated with that timing relay, means controlled at times by said other timing relay and at other times by said track switch for completing an alternate path in saidcircuit for said operating relay around the contact of the interlocking relay of said adjacent section and for disconnecting the timing relay of said adjacent'section from its operating means.

' '7. In a control system for a highway crossing signal located at the intersection of a highway with a stretch of railway track provided with a plurality of successive adjoining approach sections located to one side of and adjoining a crossing section including the intersection, each said track section being provided with a track circuit including a track relay and that section adjacent the section most remote from the intersection being provided with a track switch, the combina tion with said highway crossing signal and said track relays and saidtrack switch are; plurality of interlocking relays one for each of said approach sections except said most remote section and each having a first winding controlled by the track relay of the associated section and a second winding controlled by the track relay of the next adjoining section toward the intersection, a plurality of timing relays one for each of a plurality of said approach sections including said most remote section and at least said adjacent section, means controlled by said track relays for operating each said timing relay when its associated section is occupied provided the next adjoining section toward the crossing is vacant, two additional timing relays one for said adjacent section and one for the next succeeding section toward the intersection, means controlled by said track relays for operating each said additional timing relay when its associated section is occupied, an operating relay for controlling the operation of said highway crossing signal, a circuit including in series a contact of each first winding of the interlocking relays for normally energizing said operating relay, means controlled by each of said plurality of timing relays for at times completing an alternate path in said circuit for said operating relay around the contact of the interlocking relay for the section next adjoining the section associated with that timing relay, means controlled at times by the one of said two additional timing relays associated with said adjacent section and at other times by said track switch for completing an alternate path in said circuit for said operating relay around the contact of the interlocking relay of said adjacent section and for disconnecting the timing relay of said section from its operating means, and other means controlled by the additional timing relay of said next succeeding section for at times completing an alternate path in said circuit for said operating relay around the contact of the interlocking relay of said next succeeding section.

8. In a control system for a highway crossing signal located at the intersection of a highway with a stretch of railway track provided with a plurality of successive adjoining approach sections located to one side of and adjoining a crossing section including the intersection, the combination with said highway crossing signal and said track sections of a plurality of interlocking relays one for each of said approach sections except the section most remote from the intersection and each having a first winding responsive to trafiic in the associated section and a second winding responsive to traflic in the next adjoining section toward the intersection, a timing relay for the one of said track sections adjacent the most remote section, means for operating said timing relay when its associated section is occupied, an operating relay for controlling the operation of said highway crossing signal, a circuit including in series a contact of each first winding of the interlocking relays for normally energizing said operating relay, and means controlled by said timing relay for at times completing an alternate path in said circuit for said operating relay around the contact of the interlocking relay of the section associated with said timing relay.

9. In a control system for a highway crossing signal located at the intersection of a highway with a stretch of railway track provided with a plurality of successive adjoining approach sections located to one side of and adjoining a crossing section including the intersection, the combination with said highway crossing signal and said track sections of a plurality of interlocking relays one for each of said approach sections except the section most remote from the inter section and each having a first winding responsive to traffic in the associated section and a second winding responsive to traflic in the next adjoining section toward the intersection, two timing relays one for the section adjacent the most remote section and one for the next succeeding section toward the crossing, means for operating each of said timing relays when its associated section is occupied, an operating relay for controlling the operation of said highway crossing signal, a circuit including in series a contact of each first winding of the interlocking relays for normally energizing said operating relay, and means controlled by each of said timing relays for at times completing an alternate path in said circuit for said operating relay around the contact of the interlocking relay for the section associated with that timing relay.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,884,329 Spray Oct. 25, 1932 2,097,827 Young Nov. 2, 1937 2,176,866 Allen Oct. 24, 1939 2,406,955 Lower Sept. 3, 1946 2,439,013 Lower Apr. 6, 1948

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