US2124046A - Controlling apparatus for highway crossing signals - Google Patents

Description

July 19, 1938. E. ALLEN 2,124,046

CONTROLLING APPARATUS FOR HIGHWAY CROSSING SIGNALS Filed May 3, 1955 2 Sheets-Sheet 1 Fig.1;

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H'IS' ATTORNEY y 1938- E. M. ALLEN 2,124,046

CONTROLLING APPARATUS FOR HIGHWAY CROSSING SIGNALS Filed May a, 1955 2 Sheets-Sheet 2 A1 B1 1 1; D1 51 Pwkmzp Pit-kw Earl b'ir 5351332 QZWAMQ HIS ATTORNEY Patented July 19, 1938 UNITED STATES PATENT OFFWE CONTROLLING APPARATUS FOR HIGHWAY CROSSING SIGNALS Pa., a corporation of Pennsylvania Application May 3, 1935, Serial No. 19,696

29 Claims.

My invention relates to controlling apparatus for highway crossing signals, that is, to means for the control of signals which are placed at intersections of railways and highways for the purpose of warning users of the highway when a train is approaching.

Two features of my invention are (1) the provision of means for controlling a highway crossing signal for a track on which trains move in both directions in such a manner as to cause the operation of the signal should the track circuit apparatus controlling the signal fail to return to its normal condition after a train receding from the crossing has cleared the control limits. That is, the signal may be caused to operate either in response to traffic conditions in the regular manner or to certain trackway conditions, or both; and (2) a controlled ringing time governed automatically by the speed of a train approaching the crossing.

I will describe several forms of apparatus embodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawings, Figs. 1, 2, and 3 are diagrammatic views illustrating three forms of apparatus, each embodying my invention. Figs. 4 and 5 are diagrammatic views illustrating modified forms of the apparatus shown in Figs. 2 and 3, respectively, and each also embodying my invention.

Similar reference characters designate similar parts in all five views.

Referring now to Fig. 1, the rails I and IA of a stretch of railway track X are divided by insulated joints 2 into one relatively short section AB and into two relatively long sections B0 and C-D. Each section is provided with a track circuit including a track relay, designated by the reference character R with a distinguishing SllfilX, connected across the rails I and IA at one end of the section. and with a track battery 3 connected across the rails at the other end of the section. The track X is intersected adjacent the isolated end of section C-D by a highway designated by the reference character H. The highway crossing H is protected by a signal S, of any suitable type such, for example, as a bell or a light signal or a combination of both, which signal is controlled by a signal control relay designated by the reference character Y3.

The points B and C usually will be so located as to provide adequate warning at the crossing for trains traveling at high and low speeds, respectively. The section AB may be any convenient length and, as will be explained hereinafter, may

be utilized for determining the speed of trains approaching the crossing or may be utilized in conjunction with certain relays as a device for at times initiating the operation of the signal for trains receding from the crossing.

Associated with each track relay R1 and R2 is a repeating relay having a slow release slow pickup characteristic and designated by the reference character W with the same suffix as that used in the reference character for the associated track relay. As will be explained in detail hereinafter, the slow release slow pick-up characteristics of the relays WI and W2 are employed at times to provide proper operation of certain relays.

The reference character V2 designates a stick relay which, as will be explained in detail hereinafter, is normally effective to prevent operation of the signal S when a train is receding from the crossing but which is also effective to initiate the operation of the signal S if the track relays controlling the signal fail to assume their normal condition after a train receding from the crossing has cleared the track sections controlling such relays.

The reference character TE designates a timing device which is here shown as a time element relay. The relay TE is provided with a contact 5 which is closed only when the relay TE is in its initial deenergized condition and with contacts 6 and l which are closed only when the relay TE, after a predetermined operating time, has attained its operated condition from. energy that is applied to its operating winding.

The reference character 4 designates a source of energy which is here shown as a battery.

The signal S is controlled only by a back contact 8 of relay Y3. Signal S, therefore, will be operated when relay Y3 is released and back contact 8 becomes closed.

The signal control relay Y3 is provided with two pick-up circuits and one stick circuit. The first pick-up circuit passes from battery 4 through front contacts 9 and ll! of track relays R2 and R3, respectively, and thence through relay Y3 back to battery 4. The second pick-up circuit passes from battery 4 through contact 7 of relay TE, front contact I0 of relay R3 and relay Y3 back to battery 4. The stick circuit passes from battery 4 through contact 5 of relay TE, front contact ll of relay V2, front contact l2 of relay Y3 and relay Y3 back to battery i. The circuits controlling relay Y3, therefore, provide that if its stick circuit is opened by the releasing of relay V2, the relay Y3 will be released when relay R3 becomes released, or when relay R2 becomes released provided relay TE is not in its operated condition. The contact 5 of the relay TE is included in the stick circuit for relay Y3 as a means of checking the operation of relay TE. That is, if relay TE fails to assume its initial condition after being operated, the relay Y3 will become deenergized for trains receding from the crossing.

The repeating relay WI is controlled over the front point of contact I3 of track relay RI. Likewise, the repeating relay W2 is controlled over front contact I4 of track relay R2. Relays WI and W2, therefore, will be energized or deenergized depending upon the condition of relays RI and R2, respectively.

The stick relay V2 is provided with two pickup circuits and two stick circuits. The first pickup circuit passes from battery 4 through front contact I5 of relay WI, front contact I6 of relay R2 and-relay V2 to battery 4. The second pickup circuit passes from battery 4 through the back point of contact I3 of relay RI, back contact I! of relay W2, front contact I6 of relay R2, and relay V2 to battery 4. The stick circuits for relay V2 are identical to the pick-up circuits just traced except that the stick circuits include front contact I8 of relay V2 instead of front contact I6 of relay R2. With all apparatus in its normal condition, the relay V2, therefore, will be released when relay WI is released in response to the deenergization of relay RI by the entrance of a train into section AB proceeding towards the crossing and will be maintained in that condition by the deenergization of relay R2 until such time as the train clears section BC and relay R2 is again energized. Relay V2 will not be released by a train receding from the crossing until such train clears section BC and relay W2 picks up. When relay W2 picks up, relay V2 will become deenergized and will remain deenergized until the rear of the train clears section AB and relay WI again becomes energized.

The time element relay TE is provided with one operating circuit and with two stick circuits. The operating circuit passes from battery 4 through back contact I9 of relay WI, back contact 20 of relay V2, front point of contact 2I of relay R2 and relay TE to battery 4. The first stick circuit passes from battery 4 through back contact I9 of relay WI, back contact 20 of relay V2, contact 6 of relay TE, and relay TE to battery 4. The second stick circuit passes from battery 4 through back point of contact 2I of relay R2, contact 6 of relay TE and relay TE to battery 4. The relay TE, therefore, will be operated when the relay WI and the relay V2 are both released provided relay R2 is in its energized condition, and when the relay TE attains its operated condition, it will be maintained in that condition when the relay R2 becomes deenergized or as long as relay WI and relay V2 both remain deenergized. That is, with all apparatus in its normal condition the operation of the relay TE will be initiated when the relay WI and the relay V2 both become released in response to the entrance into section AB of a train proceeding towards the crossing, and the relay TE will be either returned to its initial condition or retained in its operated condition, depending upon the speed of the train, when such train enters section BC and relay R2 becomes released.

Having thus described the various parts of the apparatus embodying my invention illustrated in Fig. 1, I will now explain their operation.

Under normal conditions, the track relays RI,

R2 and R3 are all energized and the repeating relays WI and W2, as well as the stick relay V2 and the signal control relay Y3, are also all energized. The time element relay TE is in its initial deenergized condition. I shall now assume that an eastbound train, that is, a train moving toward the right as shown in the drawings, enters section AB while traveling at high speed and causes the deenergization of track relay RI. This opens the front point of contact I3 of relay RI. The opening of the front point of contact I3 causes the repeating relay WI to become released. The releasing of relay WI causes the stick relay V2 to become released. The operation of the time element relay TE will be initiated by the closing of its control circuit over back contact I9 of relay WI, back contact 20 of relay V2 and front point of contact 2I of relay R2. The length of section AB and the timing of relay TE usually will be so chosen that a train traveling at high speed will enter section BC before the relay TE attains its operated condition.

When the train enters section BC, relay R2 will become released. Thus, the front point of contact 2| of relay R2 will become opened so that relay TE will return to its initial condition, and front contact 9 of relay R2 also will become opened thereby opening the pick-up circuit for the relay Y3. The relay Y3 will then become released since its stick circuit is already opened by the deenergization of relay V2. The control circuit for the signal S will become established by the closing of contact 8 of relay Y3. The signal S, therefore, will operate to warn users of the highway H of the approaching train. When the train enters section CD, the relay R3 will become released so that the pick-up circuit for relay Y3 will be held open thereby continuing the operation of the signal S until the train clears section C-D.

It will be noted that since relay W2 has a slow release characteristic, this relay will be delayed in assuming its released condition a predetermined interval of time after the release of relay R2. The purpose of this delayed release is to insure the deenergization of relay V2 even if a train approaching the crossing traverses section AB at a speed sufficient to cause the release of relay R2 before the relay WI becomes released. It is obvious that under this condition relay V2 may be stuck up over its stick circuit including the back point of contact I3 of relay RI and back contact I? of relay W2 if the relay W2 were permitted to release immediately after the release of relay R2. The purpose of the slow pick-up characteristic of relay W2 will be explained more in detail hereinafter.

I shall next assume that with all of the apparatus in its normal condition, a slow moving train enters section AB from the left. When the train enters section AB, the operation of the time element relay TE will be initiated in a manner similar to that just described for a high speed train. That is, the releasing of relay RI will cause the release of the relay WI which will in turn cause the release of the relay V2 so that the oper ating circuit for the relay TE becomes closed. Since the train is traveling at slow speed, the relay TE will attain its operated condition before such train enters the section BC. When the train enters section BC, the relay R2 will become released so that the time element relay TE will be held in its operated condition by the stick circuit which includes its own contact 6 and the back point of contact 2I of relay R2. The relay cuit for relay Y3 so that the signal S may operate Y3, therefore, will be held in its energized'condition by the closing of contact I of relay TE even if front contact 9 of relay R2 and the stick circuit for relay Y3 are both opened. The signal S, therefore, will not operate when the slow moving train enters section BC. When the train enters section CD the relay R3 will become released so that the pick-up circuit for relay Y3 will become opened and relay Y3 will thereby become released to cause the operation of the signal S. When the train clears section CD, the relay Y3 will again become energized and the signal S will cease its operation.

From the foregoing description of the operation of the apparatus shown in Fig. 1, it is apparent that the operation of signal S will be initiated at point B for a fast moving train and at point C for a slow moving train. That is, the length of time of the operation of signal S will be substantially the same for a high speed train as for a low speed train.

I shall next assume that a westbound train, that is, a train moving from right to left enters section CD so that relay R3 becomes released. It is readily apparent that although the pick-up circuit for relay Y3 will become opened by the opening of front contact Iii of relay R3, the relay Y3 will be maintained in its energized condition by its stick circuit which passes over its own front contact I2, front contact ii of relay V2 and contact 5 of relay TE. The signal S, therefore, will not operate for a train in section C'D receding from the crossing. Likewise, relay Y3 will be maintained in its energized condition by virtue of its stick circuit when the train enters section BC and causes the releasing of relay R2. That is, the relay TE will be maintained in its normal condition because its operating circuit will become opened by the opening of the front point of contact 2i of relay R2 and the relay V2 will be maintained in its normal condition because its stick circuit will remain energized over front contact I5 of relay WI. Since both relays TE and V2 will be maintained in their normal condition, the stick circuit for relay Y3 will remain closed so that relay Y3 will not become deenergized while the train traverses section BC. When the train enters section AB, the releasing of relay Bl will close the back point of its contact l3 which will complete the Stick circuit for relay V2 over back contact I? of relay W2, so that relay V2 will not become released. When the train vacates section B-C, the energization of relay R2 will cause the energization of relay W2 which will in turn open the stick circuit for the relay V2. The resulting deenergization of relay V2, however, will not cause the release of relay Y3 because its pick-up circuit will be closed over front contact 9 of relay R2 and front contact In of relay R3. tion AB, the energization of relay R! will in turn energize relay WI so that the relay V2 will again become picked up. This momentary releasing of the relay V2, as will be explained more in detail hereinafter, is utilized to initiate the operation of the signal for a train receding from the crossing if the relay R3 fails to pick-up when such train vacates section CD.

The slow pick-up characteristic of relay W2 insures against the possibility of the relay V2 releasing momentarily when relay R2 becomes energized in response to the clearing of section BC by the train receding from the crossing. It is obvious that under this condition a momentary releasing of relay V2 may open the stick cir- When the train departs from secfalsely until such time as the relay R2 reaches its picked-up condition so as to establish again the pick-up circuit for relay Y3. Since, however, relay W2 does not pick up immediately after the energization of relay R2, the stick circuit for relay BZ remains closed a predetermined interval of time after the energization of relay R2 so that the pick-up circuit for relay Y3 becomes closed before its stick circuit becomes opened by the releasing of relay V2.

It will be noted that relay Wl has a slow release slow pick-up characteristic. The slow release characteristic insures that one stick circuit for relay V2 will become closed before the other stick circuit becomes opened when a train receding from the crossing enters section AB. That is, the slow release characteristic insures that front contact I5 of relay WI will not become open-ed until a predetermined time interval after the closing of backpoint of contact [3 of relay RI, so that relay V2 will be maintained in its energized condition while such train occupies both sections AB and BC. The slow pick-up characteristic of relay WI insures a predetermined time interval between the opening of one stick circuit and the closing of the other stick circuit for relay V2 when a receding train vacates section AB so that if relay R2 fails to assume its normal condition after such receding train has cleared the section BC, the relay V2 will become released. That is, when the train clears section AB so that relay Rl becomes energized, one stick circuit for relay V2 will become opened by the opening of back point of contact l3 of relay Bi and the other stick circuit will not become closed until relay Wl becomes picked up and its front. contact i5 becomes closed. This momentary releasing of relay V2 thus opens the stick circuit for relay Y3 so that relay Y3 may become deenergized if track relay R2 fails to assume its normal condition after the train clears section BC. Therefore, if relay R2 fails to return to its energized condition when the train moving from right to left clears section BC, the relay Y3 will become released when the train vacates section AB and will remain released until such time as the relay R2 is restored to its normal condition. Likewise, if relay R3 fails to assume its energized condition after the train receding from the crossing vacates section CD, the momentary opening of relay V2 when the train clears section BC will open the stick circuit for Y3 which will in turn cause the deenergization of relay Y3 since its pick up circuit is already opened by relay R3 being in the deenergized condition. The signal S, therefore, will operate for a train receding from the crossing if the track relays controlling the signal fail to assume their normal condition after such train has cleared the associated sections.

The section AB thus serves as a timing section for determining the speed of trains approaching the crossing and also, in conjunction with certain relays, as a device for initiating the operation of the signal for a train receding from the crossing if the track relays governing the signal fail to assume their normal condition after the passage of such receding train.

While for the sake of simplicity I have shown apparatus extending only in one direction from the highway H, it is understood that exactly similar apparatus both as to design and operation andextending in the opposite direction from point D will be provided for the control of signal S. The manner in which the control for the signal S may be extended in the opposite direction from the highway H will be readily apparent to those skilled in the art and, therefore, I am making no further detailed explanation herein.

Referring now to Fig. 2, the rails l and IA of track X are divided by insulated joints 2 into sections Al-Bi, BICI, Cl-DI and Dl--El. The highway H intersects the track X adjacent the point CI. Each section is provided with the usual track circuit including a track relay, designated by the reference character R with a distinguishing sufiix, connected across the rails at one end of the section and the track battery 3 connected across the rails at the other end of the section. The signal S for warning users of the highway of approaching trains is controlled jointly by track relay R2 and a signal control relay Z2 for trains approaching the highway in one direction and by track relay R3 and a signal control relay Z3 for trains approaching from the opposite direction.

The points BI and DI usually will be so located as to provide adequate warning at the intersection for trains traveling at maximum speed. The sections AIB| and Dl- E| may be any convenient length and are provided for controlling certain relays, as will be described hereinafter, in such a manner as to initiate at times the operation of the signal S for trains receding from the crossing.

Associated with each track relay RI and R4 is a repeating relay having a slow release characteristic and designated by the reference character U with a suitable distinguishing suffix.

Associated with each signal control relay Z2 and Z3 is a stick relay designated by the reference character J with .a suitable distinguishing suffix.

The repeating relays UI and U4 are effective at times to prevent the release of the signal control relays Z2 and Z3 for trains receding from the crossing. The stick relays J2 and J3, likewise, are effective at times to prevent the release of the signal control relays for trains receding from the crossing. The relays UI and U4 together with relays J2 and J3, however, as will be explained more in detail later, are effective for initiating the operation of the signal S for a train receding from the crossing if the track circuit apparatus controlling the signal fails to return to its normal condition after the train clears such control sections.

The battery 4 supplies current for the operation of the signal S and all relays other than the track relays.

The signal S is provided with two control circuits. One control circuit includes back contact 22 of relay R2 and back contact 23 of relay Z2 and the other control circuit includes back contact 24 of relay R3 and back contact 25 of relay Z3. The signal S, therefore, will be caused to operate when relays R2 and Z2 are both deenergized or when relays R3 and Z3 are both deenergized.

The repeating relays UI and U4 are controlled over the front point of contacts 26 and 21 of relays RI and R4, respectively. The relays UI and U4, therefore, will be energized or deenergized depending upon the condition of the controlling track relay.

The stick relay J2 is provided with a pick-up circuit passing from battery 4 through front contact 28 of relay R2 and relay J2 to battery 4,

and with a stick circuit passing from battery 4 through front contact 29 of relay R3, front contact 30 of relay J2, and relay J2 to battery 4. The relay J2, therefore, will become released only when both relays R2 and R3 are released and will become energized only when relay R2 is energized. The stick relay J3 is provided with a pick-up circuit passing from battery 4 through contact 3| of relay R3 and relay J3 to battery 4, and with a stick circuit passing from battery 4 through contact 32 of relay R2, front contact 33 of relay J3 and relay J3 to battery 4. The relay J3, therefore, will become released only when both relays R2 and R3 are released and will become energized only when relay R3 is energized.

The signal control relay Z2 is provided with a pick-up circuit and two stick circuits. The pickup circuit passes from battery 4 through front contact 34 of relay Ul, front contact 35 of relay R2, and relay Z2 to battery 4. The first stick circuit passes from battery 4 through front contact 34 of relay Ul, front contact 36 of relay Z2 and relay Z2 to battery 4. The second stick circuit passes from battery 4 through the back point of contact 26 of relay RI, back contact 31 of relay J2, front contact 36 of relay Z2 and relay Z2 to battery 4. The relay Z2, therefore, will become released When relay Ul is released by the entrance into section AI-Bl of a train appreaching the crossing and will become energized again only when such train clears section B l-Cl, but will be prevented from being released by a train receding from the crossing until the receding train clears section B|Cl when relay Z2 will become momentarily deenergized while the rear of the train is traversing section A|Bl.

The signal control relay Z3 is also provided with a pick-up circuit and two stick circuits. The pick-up circuit passes from battery 4 through front contact 38 of relay U4, front contact 39 of relay R3 and relay Z3 to battery 4. The first stick circuit passes from battery 4 through front contact 38 of relay U4, front contact 40 of relay Z3 and relay Z3 to battery 4. The second stick circuit passes from battery 4 through the back point of contact 2'! of relay R4, the back contact 4| of relay J3, front contact 40 of relay Z3 and relay Z3 to battery 4. Since the relay Z3 is provided with control circuits similar in all respects to those for relay Z2, the relay Z2 will function for trains moving in the opposite directions in a manner similar to that just described for relay Z2.

Having thus described the various parts of the apparatus shown in Fig. 2, I will now describe their operation.

I shall first assume that an eastbound train enters section A|Bl thereby causing the release of relay RI. When relay RI becomes re leased the relay U! will also become released thereby opening the pick-up circuit for relay Z2 so that relay Z2 becomes released. When the train enters section BI-Cl, the relay R2 will become released so that a circuit for the operation of the signal S will become closed over the back contact 22 of relay R2 and back contact 23 of relay Z2. The signal S, therefore, will operate to warn users of the highway of the approaching train. When the train enters section Cl-Dl so that relays R2 and R3 are both released, the stick relays J2 and J3 will both become released. When the train clears section BIC|, the relay R2 will become energized so that relay Z2 will become energized and the circuit for the operation of the signal S will become opened to prevent further operation of the signal. The energization of relay R2 will also close the pickup circuit for relay J2 so that relay J2 will become energized. When the train enters section DI--El, the relay R4 will become released sothat a stick circuit for the relay Z3 will become closed over the back point of contact 21 of relay R4, back contact 4! of relay J3 and front contact 43 of relay Z3. The relay Z3, therefore, will remain in its energized condition. When relay R4 becomes deenergized, the relay U4 will also become deenergized. It will be noted, however, that due to the slow release characteristic of relay U4, a stick circuit for the relay Z3 will remain closed momentarily over front contact 38 of relay U4 so that relay Z3 will be maintained in its energized condition while relay R4 is moving from its picked-up to its released condition. When the train clears section ClDl, the relay R3 will again become energized so that relay J3 will become energized. When relay J3 is energized the stick circuit for relay Z3 will become opened so that relay Z3 will become released. The signal S, however, will not operate because its operating circuit has been already opened by the picking up of relay R3. When the train clears section DIEI, the relay R4 will become picked up which will in turn pick up relay U4 so that relay Z3 will again become energized.

If, when the train clears section Cl-DI, the relay R3 fails to return to its energized condition then a circuit for the operation of signal S will be closed by the release of relay Z3 in response to energization of relay R4 when the train vacates section DIE| and prior to the picking up of relay U4. That is, if relay R3 fails to assume its normal condition after the passage of the train through section C l-Dl, the signal S will be caused to operate and will continue to operate until relay R3 is restored to its energized condition.

Referring now to Fig. 3, the track X is again divided into sections Al-Bl, Bl-Cl, Cl-Dl and D|-El. Each section AIB| andDl-E'l is provided with the usual track circuit including the track relay designated by the reference character R with a suitable suffix and the track battery 3. Each section Bl-Cl and CIDI is also provided with the usual track circuit including a track relay designated by the reference character P with a distinguishing sufiix and the track battery 3. The relays P2 and P3 are here shown as magnets of an interlocking relay designated by the reference character K.

The magnet P2 of the interlocking relay K is provided with a flagman contact 43 and the usual front and back contacts 44 and 45, respectively. Likewise, the magnet P3 is provided with a fiagman contact 46 and the usual front and back contacts 41 and 48, respectively.

The signal S may be controlled over back contact 45 of the magnet P2 or back contact 48 of the magnet P3. Thus, signal S will be operated when either magnet P2 or P3 is in its full released condition but will not be operated when the magnets are in their locked condition.

Associated with the track relay R4 is a slow pick-up relay designated by the reference character Q4. The relay Q4 may be picked up over a front contact 49 of relay R4 or front contact 4'! of magnet P3. Thus relay Q4 will become released only when contacts 49 and 47 are both opened and may become energized when either contact is closed. Associated with the track relay RI is a slow pick-up relay designated by the reference character Ql. The relay Ql may be picked up over a front contact 50 of relay RI or front contact 44 of magnet P2. Thus, relay QI will become released only when contacts 50 and 44 are both opened and may become energized when either contact is closed.

The battery 4 supplies current for all apparatus except the track relays and may also at times furnish current for the energization of magnets P2 and P3.

Associated with the magnets P2 and P3 are two resistors designated by the reference character T with a suitable distinguishing sufiix. The resistors T2 and T3 are effective at times to limit the current applied to magnet P2 and P3, respectively. That is, the resistors T2 and T3 are provided to prevent excessive energization of the magnets P2 and P3 when, as will be explained more in detail hereinafter, these magnets are energized by battery 4, since the voltage of battery 4 usually will be considerably in excess of the voltage of track battery 3 from which these magnets are normally energized.

The magnet P2 is normally energized by its track battery 3 but may also be energized by a pick-up circuit which passes from battery 4 through front contact 50 of relay RI, back contact 5| of relay Ql, resistor T2, fiagman contact 43 of magnet P2, magnet P2, and back contact 52 of relay Q! to battery 4. The magnet P3 is normally energized by its track battery 3 but may also be energized by a pick-up circuit which passes from battery 4 through front contact 49 of relay R4 and back contact 53 of relay Q4, resistor T3, flagman contact 46 of magnet P3, magnet P3, and back contact 54 of relay Q4 to battery 4.

Having thus described the various parts illustrated in Fig. 3, I will now explain their operation.

I shall first assume that an eastbound train having already entered section AIBI so that relay Rl becomes released now enters section Bl-C|. When the train enters section B l-C l the magnet P2 becomes released so that a circuit for the operation of signal S becomes closed. Thus signal S, therefore, operates to warn users of the highway of the approaching train. When the train clears section Bl-Cl, the magnet P2 will again become energized so that operation of signal S is discontinued. When the train enters section ClDI, the magnet P3 becomes released. Due to the interlocking character of the relay, the flagman contact 46 will not become opened. Front contact 41, however, will become opened but back contact 48 will not become closed. While the train occupies section Cl-Dl, therefore, the control circuit for the signal S will not become closed. When the train enters section D.I-EI

the relay R4 becomes deenergized thereby opening its front contact 49 so that relay Q4 becomes deenergized because its other pick-up circuit is already open at front contact 41 of magnet P3. When the train clears section C l-Dl, the magnet P3 will again become energized and when the train clears section DlEl, relay R4 and relay Q4 will become energized so that all apparatus will be again in the normal condition.

If, when the train clears section CI--Dl the magnet P3 fails to assume its picked-up condition so that the interlocking feature of the relay K remains effective, the relay Q4 will remain deenergized to establish the pick-up circuit for magnet P3 as soon as the train clears section DIE| and relay R4 becomes energized. Due to the slow pick-up characteristic of relay Q4, the magnet P3 will be momentarily energized so that the interlocking feature of the relay K will be released thus allowing the magnet P3 to assume its released condition as soon as relay Q4 becomes energized in response to the energization of relay R4. The signal S, therefore, will be caused to operate by the closing of back contact 48 of magnet P3, and will continue to so operate until such time as the magnet P3 is restored to its normal condition.

Referring now to Fig. 4, which is a modification of Fig. 2, the track X is divided into sections BI-CI and CIDI. The sections BI-CI and CIDI are provided with the usual track relays R2 and R3 each energized by the usual track battery 3. The sections AI-BI and DIEI are eliminated and their functions performed by track instruments designated by the reference characters M and N with a suitable distinguishing suffix.

The track instruments MI and M4 are provided with normally closed contacts 56 and 51, respectively, which may be opened by trains passing over the instruments in either direction. The track instruments NI and N4 are provided with normally open contacts 58 and 59, respectively, which may be closed only by trains receding from the crossing. The instruments MI and M4 usually will be termed non-directional instruments since they function for trains moving in either direction, and the instruments NI and N4 usually will be termed directional instruments since they function for trains moving in one direction only. No further detailed explanation is required here regarding the track instruments since such devices are well known to those skilled in the art.

The signal control relay Z3 is provided with a pick-up circuit and with two stick circuits. The pick-up circuit for relay Z2 includes only front contact 60 of relay R2. The first stick circuit for relay Z2 includes its own front contact BI and normally closed contact 56 of instrument MI, The other stick circuit includes its own front contact 6i and normally open contact 58 of instrument NI. The relay Z2, therefore, may be released when front contact 60 of relay R2 becomes opened provided contact 56 is also opened, and may be prevented from releasing if either contact 56 or 58 is closed even if front contact 60 is opened. The signal control relay Z3 is also provided with a pick-up circuit and with two stick circuits. The pick-up circuit for relay Z3 includes front contact 62 of relay R3. The first stick circuit for relay Z3 includes its own front contact 63 and normally closed contact 51 of instrument M4. The other stick circuit includes front contact 63 and normally open contact 59 of track instrument N4. The relay Z3, therefore, may be released when contact 62 of relay R3 becomes opened provided contact 5'! is also opened, and may be prevented from releasing if either contact 5'! or 59 is closed even if front contact 62 is opened.

The signal S may be controlled by a circuit including back contact 64 of relay R2 and back contact 65 of relay Z2, or by a circuit including back contact 66 of relay R3 and back contact 61 of relay Z3. The signal S, therefore, will operate when both relays R2 and Z2 are released or when both relays R3 and Z3 are released.

Having thus described the various parts of Fig. 4, I will now describe their operation.

I shall assume that an eastbound train having already passed over track instruments MI and NI enters section BI-CI so that relay R2 becomes released. When the train passed over instruments MI and NI, contact 56 became opened but contact 58 did not become closed, therefore, the stick circuit for relay Z2 became opened so that relay Z2 will be released when its pick-up circuit becomes opened by the releasing of relay R2. When relay R2 and relay Z2 both become released, the signal S will be caused to operate and will continue to operate as long as the train occupies section BI-CI. When the train enters section CIDI, the relay Z3 does not become released because one of its stick circuits remains closed over contact 51 of instrument M4 even though its pick-up circuit becomes opened by the releasing of relay R3. When the train passes over the track instrument N4 the other stick circuit for relay Z3 becomes closed by the closing of contact 59 so that when the train passes over instrument M4 and opens contact 51, the relay Z3 will not become released. When the train clears section CIDI, the relay R3 will again become energized which in turn will close the pick-up circuit for relay Z3 so that this relay will not be released even if both its stick circuits become opened by the opening of contact 51 of instrument M4 during the time the rear of the train passes from instrument N to instrument M4.

If, when the train clears section CI-DI, the track relay R3 fails to assume its normal condition, then when the rear of the train passes off instrument N4 so that contact 59 again becomes opened before contact 51 closes, the relay Z3 will become released because its pick-up circuit is already opened at front contact 62 of relay R3 and its other stick circuit is broken by the opening of contact 51 of instrument M4. When relays R3 and Z3 both become released, the signal S will be caused to operate and will continue to operate until relay R3 is restored to its energized condition.

Referring now to Fig. 5, which is a modification of the apparatus illustrated in Fig. 3, the track X is divided into sections BICI and CI DI. The sections AIBI and DIEI are eliminated and their functions performed by directional track instruments designated by the reference characters LI and L4, respectively. The track instruments LI and L4 are provided with normally closed contacts 10 and II, respectively, which may be opened only by trains receding from the crossing.

The signal S may be operated by a circuit controlled over back contact 45 of magnet P2 or by a circuit controlled over back contact 48 of magnet P3. Signal S, therefore, will operate when either magnet P2 or magnet P3 is in its full released condition.

The magnets P2 and P3 of the interlocking relay K are normally energized by their respective track batteries 3 but may also be energized at times by the releasing of slow pick-up relays QI and Q4. That is, magnet P2 also may be controlled over a circuit which passes from battery 4 through contact 10 of instrument LI, back contact 5| of relay QI, resistor T2, magnet P2, and back contact 52 of relay QI to battery 4; and magnet P3 also may be controlled over a circuit which passes from battery 4 through contact II of instrument L4, back contact 53 of relay Q4, resistor T3, magnet P3, and back contact 54 of relay Q4 to battery 4. Magnet P2, therefore, may be energized by the track battery 2 or may be energized by battery 4 when relay Q! is released provided contact II! of instrument Li is closed. Likewise, magnet P3 may be energized by its track battery or by battery 4 when relay Q4 is released provided contact H of instrument L4 is closed.

The relay Q! may be energized over front contact 44 of magnet P2 or contact 10 of track instrument Li, and relay Q4 may be energized over front contact 41 of magnet P3 or contact H of track instrument L4. The relay QI, therefore, may be released if contact 10 of instrument LI and contact i l of magnet P2 are both opened, and may be energized if either of these contacts are closed. Likewise, the relay Q4 may be energized or deenergized in a similar manner by the condition of instrument L4 and magnet P3.

Having thus described the various parts illustrated in Fig. 5, I will now describe their operation.

I shall assume that an eastbound train having already passed over track instrument Ll enters section BiCl so that magnet P2 becomes released. When magnet P2 is released the signal S is caused to operate and continues to operate until the train clears section B|--C|. When the train enters section Cl-Dl, the magnet P3 of the interlocking relay K becomes released but, due to the interlocking feature of this relay, contact 18 will not become closed so that signal S will not operate. When the train clears section C!-Dl, the magnet P3 again becomes energized and relay Qil also again becomes energized.

If, when the train clears section C|Dl, the magnet P3 fails to assume its picked-up condition, then, when the train passes over track instrument L6 so that relay Q4 becomes released, a pick-up circuit for magnet P3 becomes momentarily closed when contact ll of instrument L 3 recloses as the train clears the instrument L4. The slow pick-up characteristic of relay Q4 maintains this pick-up circuit closed until relay Q i becomes picked up so that magnet P3 will be energized momentarily which in turn will release the interlocking pawl of relay K. When the interlocking pawl is released, magnet P3 will be permitted to drop to its full released condition so that back contact 48 becomes closed to cause the operation of the signal S as a warning that the magnet P3 did not return to its picked-up condition after the passage of the train.

While in Figs. 2, 3, 4, and 5, I have described the operation of the apparatus illustrated therein for trains moving in one direction only it is understood that the apparatus in these views operates in substantially the same manner for trains moving in the opposite direction.

The apparatus embodying my invention, therefore, provides a simple and reliable means for operating a highway crossing signal in which normal operation of the signal is provided for an approaching train and in which operation of the signal is also provided in the event of failure of the track circuit apparatus controllng the signal to assume its normal condition after the passage of such train receding from the crossing. in other words, the integrity of the track circuit apparatus controlling the signal is checked each time a train moves over such apparatus.

Although I have herein shown and described only a few forms of apparatus embodying my 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 my invention.

Having thus described my invention, what I claim is:

1. In combination, a stretch of railway track intersected by a highway, a highway crossing signal at the intersection of said stretch and said highway, a track circuit included in said stretch and having a track relay, directional means controlled by the track relay for causing said signal to operate when a train occupies said track circuit and is approaching the intersection but for preventing the signal from operating when a train occupies said track circuit and is receding from the intersection, a train operated device operable by the departure of such receding train from a zone adjacent said track circuit but re mote from the intersection, and means rendered efiective to cause said signal to operate if said track relay is released when said device is operated.

2. In combination, a stretch of railway track intersected by a highway, a highway crossing signal at the intersection of said stretch and said highway, a track circuit included in said stretch and having a track relay,-directional means for causing the operation of said signal when said track relay is released by a train approaching the intersection in said track circuit but for preventing the operation of said signal when said track relay is released by a train receding from the intersection in said track circuit, a device responsive to the presence of a train at a point adjacent said track circuit but remote from the intersection, and means controlled by said device for rendering said directional means ineffective to prevent the operation of said signal if said track relay remains released after a receding train vacates said track circuit.

3. In combination, a stretch of railway track intersected by a highway, a highway crossing signal at the intersection of said stretch and said highway, an interlocking relay for controlling said signal, a track circuit adjacent the intersection normally effective to energize said interlocking relay, a train operated device responsive to the presence of a train at a point adjacent said track circuit but remote from the intersection, and means controlled by said train operated device for at times energizing said interlocking relay when a train is receding from the intersection. 1

4. In combination, a stretch of railway track intersected by a highway, a highway crossing signal at the intersection of said stretch and said highway, an interlocking relay for controlling said signal, a track circuit adjacent the intersection normally effective to energize said interlocking relay, a track instrument responsive to the presence of a train at a point adjacent said track circuit but remote from the intersection, and means controlled by said track instrument for at times energizing said interlocking relay when a rain is receding from the crossing.

5. In combination, a stretch of railway track intersected by a highway, a highway crossing signal at the intersection of said stretch and said highway, an interlocking relay for controlling said signal, a track circuit adjacent the intersection normally effective to energize said interlocking relay, other track circuit apparatus responsive to the presence of a train in a section adjacent said track circuit but remote from the intersection, and means controlled jointly by said interlocking relay and by said other track circuit apparatus for at times energizing said interlocking relay when a train is receding from the crossing.

6. In combination, a stretch of railway track intersected by a highway, a highway crossing signal at the intersection of said stretch and said highway, apparatus for at times controlling said signal, means for placing said signal under control by said apparatus when a train is occupying a zone adjacent the intersection and is approaching the intersection but for removing said signal from control by said apparatus when a train is occupying such zone and is receding from the intersection, a train operated device responsive to the presence of atrain in a zone remote from the intersection, and means controlled by said train operated device for at times restoring said signal to control by said apparatus when a receding train vacates such remote zone.

'7. In combination, a stretch of railway track intersected by a highway, a highway crossing signal at the intersection of said stretch and said highway, apparatus for at times controlling said signal, means for placing said signal under control by said apparatus when a train is occupying a zone adjacent the intersection and is approaching the intersection but for removing said signal from control by said apparatus when a train is occupying such zone and is receding from the intersection, track circuit means responsive to the presence of a train in a zone remote from the intersection, and means controlled by said track circuit means for at times restoring said signal to control by said apparatus when a receding train departs from such remote zone.

8. In combination, a stretch of railway track intersected by a highway, a highway crossing signal at the intersection of said stretch and said highway, apparatus for at times controlling said signal, means for placing said signal under control by said apparatus when a train is occupying a zone adjacent the intersection and is approaching the intersection but for removing said signal from control by said apparatus when a train is'occupying such zone and is receding from the intersection, track instrument means responsive to the presence of a train in a zone remote from the intersection, and means controlled by said track instrument means for at times restoring said signal to control by said apparatus when a receding train departs from such remote zone.

9. In combination, a stretch of railway track intersected by a highway, a highway crossing signal at the intersection of said stretch and said highway, a track circuit included in said stretch and having a track relay, directional means including said track relay and having a normal condition but operable to a different condition to cause the operation of said signal when a train is approaching the intersection in said track circuit and to another condition to prevent the operation of said signal when a train is receding from the intersection in said track circuit, a train operated device operable when such receding train departs from a zone adjacent said track circuit but remote from the intersection, and means effective to cause said signal to operate if said directional means is in such other condition when said device is operated but ineffective to cause said signal to operate if said directional means is in its normal condition when said device is operated.

10. In combination, a stretch of railway track, a highway crossing signal at the intersection of said stretch and said highway, means for initiating the operatiton of said signal when a certain zone adjacent the intersection is occupied by a train approaching the intersection effective at one point or another depending upon the speed of the train, means for preventing the operation of said signal when such certain zone is occupied by a train receding from the intersection, track circuit apparatus responsive to the presence of a train in another zone more remote from the intersection, and means controlled by said track circuit apparatus for at times initiating the operation of said signal when a receding train departs from such certain zone.

11. In combination, a stretch of railway track intersected by a highway, a first and a second and a third section included in said stretch and each having a track relay, a highway crossing signal at the intersection of said stretch and said highway, a signal control relay controlled in part by the track relays for the second and third section, a timing device controlled by the track relays for the first and second sections for causing the sig nal control relay to initiate the operation of said signal when an approaching train enters said second or said third section depending upon the speed of the train, a directional stick relay controlled by the track relays for the first and second sections for preventing the signal control relay from operating said signal when a receding train occupies the second, and third sections, means for causing said signal control relay to operate said signal if the track relay for the third section is released when such receding train departs from the second section, and means for causing said signal control relay to operate said signal if the track relay for the second section is released when such receding train departs from the third section.

12. In combination, three successive sections of railway track, a highway intersecting said track adjacent the isolated end of the third section, a track circuit including a track relay for each section, a signal control relay controlled at times by the track relays for the second and third sections, another relay controlled in part by the track relay for the first section and effective to remove the signal control relay from control by the track relays for the second and third sections when the associated sections are occupied by a train receding from the crossing but effective to restore said signal control relay to control by the track relays for the second and third sections when such receding train departs from these sections, and a highway crossing signal controlled by said signal control relay.

13. In combination, three successive sections of railway track, a highway intersecting said track adjacent the isolated end of the third section, a track circuit including a track relay for each section, a first repeating relay for the track relay for the first section, a second repeating relay for the track relay for the second section, a stick relay, one pick-up circuit for said stick relay including a front contact of said first repeating relay and a front contact of the track relay for the second section, a second pick-up circuit for said stick relay including a back contact of the track relay for the first section and a back contact of said second repeating relay as Well as a front contact of the track relay for the second section, a first stick circuit for said stick relay including its own front contact and a front contact of said first repeating relay, a second stick circuit for said stick relay including its own front contact and a back contact of said second repeating relay as well as a back contact of the track relay for the first section, a signal control relay controlled in part by the track relays for the second and third sections and by said stick relay, and a highway crossing signal controlled by said signal control relay.

14. In combination, three successive sections of railway track, a. highway intersecting said track adjacent the isolated end of the third section, a track circuit including a track relay for each section, a slow pick-up relay controlled by the track relays for the first and second sections, a stick relay controlled by the track relays for the first and second sections, a signal control relay controlled by the track relays for the second and third sections as well as by said slow pick-up relay and said stick relay, and a highway crossing signal controlled by said signal control relay.

15. In combination, three successive sections of railway track, a highway intersecting said track adjacent the isolated end of the third section, a track circuit including a track relay for each section, a first and a second slow pick-up slow release relay for the first and second sections respectively, a stick relay controlled by the track relays for the first and second sections as well as by said first and second slow pick-up slow release relays, and a highway crossing signal controlled by the track relays for the second and third sections as well as by said stick relay.

16. In combination, three successive sections of railway track, a highway intersecting said track at the adjacent ends of the second and third sections, a track relay for each section, a slow release relay controlled by the track relay for the first section, a stick relay controlled by the track relays for the second and third sections, a signal control relay, a pick-up circuit for said signal control relay including a front contact of said slow release relay and a front contact of the track relay for the second section, a first stick circuit 'for said signal control relay including its own front contact and a front contact of said slow release relay, a second stick circuit for said signal control relay including its own front contact and a back contact of the track relay for the first section as well as a back contact of said stick relay, and a highway crossing signal controlled by said signal controlrelay.

17; In combination, a section of railway track, a highway intersecting said track adjacent one end of said section, a track circuit including a track relay for said section, an auxiliary circuit for said track relay, a directional track instrument adjacent the other end of said section and operable only by a train receding from the intersection, means for at times energizing said auxiliary circuit when said directional track instrument is operated, and a highway crossing signal controlled by said track relay.

18. In combination, a section of railway track, a highway intersecting said track adjacent one end of said section, a track circuit including a .track relay for said section, an auxiliary circuit for said track relay, a slow pick-up relay, means for initiating the operation of said slow pick-up relay when a train receding from the intersection departs from a zone adjacent the other end of said section, and means effective before said slow pick-up relay completes its operation to energize at times said auxiliary circuit, and a highway crossing signal controlled by said track relay.

19. In combination, a section of railway track including a track circuit having a track relay, a highway intersecting said track adjacent one end of said section, a non-directional track instrument located adjacent the other end of said section, a directional track instrument located between such other end of said section and said non-directional instrument, a normally open contact operated by the directional track instrument and. closed only for trains receding from the intersection, a normally closed contact operated by the non-directional instrument and opened by trains moving in either direction, a stick relay, a pick-up circuit for said stick relay including a front contact of the track relay, a first stick circuit for said stick relay including its own front contact and said normally open contact, a second stick circuit for said stick relay including its own front contact and said normally closed'contact, and a highway crossing signal controlled jointly by said stick relay and said track relay.

20. In combination, a stretch of railway track including an intersection with a highway, a highway crossing signal located at said intersection, a track instrument normally in one condition but operable to a different condition when a train approaching said intersection passes a point remote from the intersection, means for initiating the operation of said signal when such train enters: a certain zone extending from said remote point to the intersection provided said track instrument is then in such different condition, and means 'eifective thereafter to continue the operation of said signal as long as such train occupies said zone.

21. In combination, a section of railway track including an intersection with a highway adjacent one end of said section, a track circuit including a track relay for said section, a highway crossing signal at the intersection governed by said track relay, another relay operable by a train in a zone adjacent the other end of said section, and an auxiliary circuit including directional means for at times energizing said track relay when said other relay is operated.

22. In combination, a section of railway track including an intersection with a highway adjacent one end of said section, a track circuit including a track relay for said section, a highway crossing signal at the intersection governed by said track relay, another relay operable by a train in a zone adjacent the other end of said section, an auxiliary circuit, a source of energy, and directional means included in said auxiliary circuit for at times connecting said source of energy to said track relay when said other relay is operated.

23. In combination, a section of railway track including an intersection with a highway adjacent one end of said section, a track circuit including an interlocking relay for said section, a highway crossing signal governed by said interlocking relay, another relay which becomes deenergized when a train receding from the intersection occupies a zone adjacent the other end of said section, and an auxiliary circuit for said interlocking relay including a back contact of said other relay.

24. In combination, a section of railway track including an intersection with a highway adjacent one end of said section, a track circuit including an interlocking relay for said section, a highway crossing signal governed by said interlocking relay, another relay which becomes deenergized when a train receding from the intersection occupies a zone adjacent the other end of said section, and an auxiliary circuit for said interlocking relay including its own front contact and a back contact of said other relay.

25. In combination, a section of railway track including an intersection with a highway adjacent one end of said section, a track circuit including an interlocking relay for said section, a highway crossing signal governed by said interlooking relay, another relay, a circuit for energizing said other relay controlled by traffic conditions in a zone adjacent the other end of said section, another circuit for energizing said other relay including a front contact of said interlocking relay, and means governed by said other relay for at times controlling said interlocking relay.

26. In combination, a stretch of railway track including an intersection with a highway, a first track section and a second track section included in said stretch and successively occupied when a train is approaching said intersection, a track circuit for each section including a first track relay and a second track relay respectively, a first auxiliary relay which becomes energized or deenergized according as said first track relay is picked up or released, a second auxiliary relay which at times becomes released when said second track relay is released, a signal control relay, a pickup circuit for said signal control relay including a front contact of said first auxiliary relay and a front contact of said second track relay, a stick circuit for said signal control relay including a front contact of said first auxiliary relay, another stick circuit for said signal control relay including a back contact of said second auxiliary relay as Well as a back contact of said first track relay, and a highway crossing signal governed by said signal control relay.

2'7. In combination, a stretch of railway track including an intersection with a highway, a first track section and a second track section included in said stretch and successively occupied when a train is approaching said intersection, a first track relay and a second track relay for said first and second sections respectively, a signal control relay, a highway crossing signal which is caused to operate when both said signal control relay and said second track relay are released, means effective to release said signal control relay when either said first track relay or said second track relay is released by a train approaching said intersection but eifective to prevent the release of said signal control relay when said second track relay becomes released by'a train receding from said intersection, and means governed by said first track relay effective to release said signal control relay when a train receding from said intersection vacates said first section provided said second track relay failed to become picked up when such receding train vacated said second section.

28. In combination, a stretch of railway track including an intersection with a highway, a first track section and a second track section included in said stretch and successively occupied when a train is approaching said intersection, a first track relay and a second track relay for said first and second sections respectively, a signal control relay, a highway crossing signal which is caused to operate when both said signal control relay and said second track relay are released, means efiective to release said signal control relay when either said first track relay or said second track relay is released by a train approaching said intersection but effective to prevent the release of said signal control relay when said second track relay becomes released by a train receding from said intersection, and means including an auxiliary relay controlled by said first track relay effective to release said signal control relay when a train receding from said intersection vacates said first section provided said second track relay failed to become picked up when such receding train vacated said second section.

29. A track circuit for railroads comprising, a track battery connected across the track rails at one end of the track section, a relay in series with said battery, a separate source of direct current, and means for at times connecting said separate source across the track rails at the other end of the track section to act cumulatively with said track battery to increase the current through said relay and cause effective energization thereof.

EARL M. ALLEN.

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