US2038504A - Signaling system for railroads - Google Patents

Description

pril 2H, 1936. s. N. WIGHT l S'IGNALING SYSTEM FOR RAILROADSV Filed Aug. 3o, l1929 VATTORNEY Patented Apr. 21, 1936 Nrrso STATES SIGNALING SYSTEM FOR RAILROADS Sedgwick N. Wight, Rochester, N. Y., assignor to 1(rcrxizeral Railway SignalV Company, Rochester,

Application August 30, 1929, Serial No.- 389,446

17 Claims.

This invention relates to devices and systems for protecting train movements over power operated switches, and more particularly to means for locking such switches under predetermined conditions of trafiic, and is an improvement over the systems shown in my prior applications Ser. No. 48,553 led August 6, 1925 and Ser. No. 120,423 filed July 3, 1926.

Where track switches, operated by power under lo the control of an operator, are employed, it is important that suitable pro-vision be made to prevent the operator from carelessly or accidentally causing operation of the switch by power in front of an approaching train, at such times and under such conditions that otherwise the switch might be in mid-stroke or unlocked when the train starts to pass over it. If the track is provided with track circuits for a sufcient distance from the switch, such desired protection may be obtained by the application of some one of the well known schemes of track circuit controlled approach locking; but in some cases, as on a passing siding or branch track, or the like, such track circuits may not be available to indicate they presence of a train approaching the switch, so that the ordinary types of track circuit controlled: approach locking are not adequate to protect the movement of a train from such a siding or branch track.

With these considerations in mind, in accordance with the present invention, it is proposed to employ a time element device, in combination with suitable control circuits and a stick relay or its equivalent, in such a way that, whenever the signal is cleared to advance trafc from the siding, branch track, or other portion of track adjacent the switch and not equipped with track circuits, the switch can not thereafter be operated by power, even though this signal is afterwards 40 caused to indicate stop, until after the lapse of predetermined time after a signal has been put to stop, sufficient to permit an approaching train either to come to a stop at the signal, or reach the point where the presence of the train prevents operation of the switch, dueI to the usual detectcr track circuit, or the like.

The characteristic features and advantages of the invention Will be in part apparent to those skilled in the art, and in part pointed out, as thel description progresses.

The accompanying drawing shows in al simplifled and diagrammatic manner one specic embodiment of the invention, applied to an electri-y cally operated switch at the end of a passing sidv ing, the various parts and circuits involved in the invention being shown more with the object of facilitating explanation and understanding of the nature of the invention, than with the purpose of illustrating in detail the structure and arrangement of parts and circuits preferably employed in practice.

Referring to the accompanying drawing, one end of a passing siding PS has been shown, with a track switch SW. The main track, and the portion of the siding up to the fouling point are provided with insulated joints and cross bonding, in accordance with common practice, to form a detector track circuit DTC, having a track relay T. The points of the switch SW are locked and operated by a suitable power switch machine SM, which is assumed to beof the well known electrically operated type, such asY disclosed, for example, in the patent to W. K. Howe, No.- 1,466,903, dated September 4, 1923. It is assumed that the operation of this switch machine SM to its normal and reverse positionsfrom a local source of current, as a. battery 5, is controlled by an operator at',` a distant point, by means of a suitable remote controlA relay, such as a neutral polar relay Z, which may be energized with `current of one or the other polarity, or de-energized, over line wires 6 and v'1, from a distant battery 8, in accordance with the position of a manually operable polechanging switch 9. 'I'he switch machine SM, however, may be operated or controlled in any other suitable way, without departing from the invention.

In the specific embodiment of the invention shown, the operation of the switch machine SM is prevented, as and when desired, by directly controlling the supply of current from the bat'- tery 5 to the switch machine motor, although other `expedienta'well known in the art, may be employed for this same purpose. As shown, the connection from the battery 5 to the switch machine SM includes the front contact Illof the detector track relay T, and the front contact Il of a lock relay LR, so that no power can be supplied to the switch machine, irrespective of the position of the control relay Z, if the detector track circuit DTC is occupied, or if the lock relay LR is de-energized.

Signals I 2 and l3fgovern traic toward the siding; signal I4 governs traffic on the main track; and signal l5, assumed to be a dwarf signal, governs traffic from the siding, all in accordance with common practice. These signals |2|5 have been illustrated as semaphore signals, but trackway signals of any suitable type may be employed, such as color light signals. In accordance with this invention, these signals I2 to I5 are provided with suitable circuit controllers I6, I'I, I8 and I9, respectively, which are closed only if the corresponding signal is in its stop position. If color light signals are employed, suitable contacts on their control relays, or equivalent means, would be employed instead of such circuit controllers. The dwarf signal I5 is also provided with a circuit controller 25, closed when this signal indicates stop.

These several signals I2-I5 are governed in accordance with the position of the switch SW, the presence or absence of trains in advance of the respective signals, and under the control of the operator, in some suitable way in accordance with common practice. For example, these signals may be controlled by separate levers, or may be remotely controlled, in accordance with the principles of the dispatching system disclosed, for example, in my prior application, Ser. No. 48,553, iiled August 6, 1925. Any suitable method of control of these signals, including the block signal circuits, may be employed in accordance with the invention.

The invention contemplates a suitable time element device TE, and a stick relay S, or equivalent means. This time element device TE may be of any suitable construction, operable electrically to close contacts after the lapse of a predetermined time, such as 20 seconds. As shown diagrammatically, this time element device is of the thermal element type, such as disclosed more in detail in my prior application Ser. No. 292,884, dated July 14, 1928, now matured into Patent No. 1,856,045, granted April 26, 1922, and comprises two thermal bi-metallic contact iingers 2I and 22, normally open, and adapted to be closed, after the lapse of a predetermined time, following the supply of heating current to a coil 23 on the nger 22.

For simplicity in illustration, the control circuits for the relays LR and S, and the thermal time element device TE, have been shown conventionally with the symbols (-1-) and indicating the opposite terminals of a suitable battery, or other source of current.

Operation-The stick relay S is normally energized, assuming that the dwarf signal I5 has not been cleared since the last movement of a train over the switch, by a circuit which may be traced as follows: starting at (-1-), circuit controller 20 of signal I5, wires 25 and 26, coil 23 of time element device TE, wire 21, front contact 28 of relay S, wires 29 and 30, relay S, to On account of the resistance ofthe relay S in this circuit, the

current in the coil 23 is not sufficient to heat the thermal nger 22.

With the stick relay S energized, and all of the signals l2-I 5 in the stop position, and assuming no train approaching the switch from either direction on the main track, the lock relay LR is energized by a circuit which may be traced as followsz-starting at (-1-), front contact 3l of relay S, wire 32, circuit controller I8 of signal I4, wire 33, circuit controller I9 of signal I5, wire 34, circuit controller I6 of signal I2, wire 35, circuit controller I'I of signal I3, wire 36, contact a, wire 31, relay LR, to The contact a in this circuit and its controlling relay b represent diagrammatically such contact or contacts as are necessary to provide approach locking protection for the switch SW for trains approaching on the main track in either direction. Such approach locking circuits, although some suitable form is preferably employed in the practical application of the invention, are not material to the invention, and may be of any suitable type, such as disclosed, for example, in my prior application, Ser. No. 48,553, led August 6, 1925.

Under the conditions assumed, that is, with the signals I2-I 5 all indicating stop, and no train approaching from either direction on the main track, and with the lock relay LR energized, the switch machine SM may be supplied with current to operate the switch points to either position, dependent upon the position of the manually operable switch 9 and energization of the remote control relay Z.

Considering now the train movement, to which this invention more particularly relates, assume that the operator, having caused the switch SW to assume the reverse position, and having cleared the dwarf signal I5, with the idea of permitting a train to move from the passing siding PS onto the main track, should for some reason change his mind, and cause the signal I5 to assume the stop position; or, perhaps, the manipulation clearing the signal I5 was made accidentally or thoughtlessly, and is then changed. Under these conditions, if there should happen to be a Vtrain on the passing siding PS approaching the signal I5, and if the engineman observing this signal in the clear position, should maintain `or increase speed, this train might not be able to stop, when the signal I5 was placed in the stop position; and unless some special provisions were made to prevent operation of the switch machine, other than merely the fact that the signal I5 is in the stop position, the switch machine might be operating at the time the train in question entered the detector track circuit DTC, with the result that the train might reach the Switch points when unlocked or in mid-stroke. This would be true if the entrance of the train into the detector track circuit DTC should at once cut off the power for operating the switch machine, as in the arrangement shown, or if provisions were made, as shown, for example, in the patent to W. K. Howe No. 1,399,257, dated December 6, 1921, to permit the switch machine to complete the cycle of operation that had been started. Although such a train movement would trail through the switch points, and might not derail the train,

the possible injury to the switch points or switch operating mechanism makes it desirable to avoid such a contingency. Also, under the conditions assumed, the switch machine may be operated to its normal position, and under certain circumstances the signals I2 or I4 cleared, with the possibility that conflicting train movements on the main track might occur under conditions that might be unsafe with a train coming oil" of the siding.

This invention prevents operation of the switch under the conditions assumed. When the dwarf signal I5 is cleared, its circuit controller 28 opens and de-energizes the stick relay S, thereby breaking at its iront contact 3| the energizing circuit for the lock relay LR, so as to prevent application of power to the swit-ch machine SM. When the signal I5 is caused to assume its stop position by the operator, as in the case assumed, the stick relay S and the lock relay LR remain de-energized; Vand the switch machine SM cannot again be operated until the relay S is again picked up.

When the signal I5 is put back in its stop position, closing its circuit controller 2D, the coil 23 of the time element device TE is supplied with current through a circuit from circuit controller 2l), wires 25 and 26, coil 23, wire 21 and back contact 28 of relay S, to This circuit for the coil 23 does not include the relay S; and this current in the coil 23 is sucient to heat the thermal element constituting the nger 22 and cause this linger to contact with the other linger 2I, after a time interval, thereby establishing a pick-up circuit for the relay S from circuit controller 20, wires 25 and 26, fingers 22-2I, wires38, 39, and 3D, relay S to When the relay S is thus re-energized, it breaks at its back contact 28 the heating circuit for the coil 23, which then cools, opening the contacts 2I-22, ready for the next operation.

The time element device TE is so designed and adjusted that, before the contact iingers 2|-22 engage each other, a predetermined time, such as 20 seconds must elapse. This time interval is selected such that a train o-n the passing siding PS, approaching the signal I5, will either have time to stop, after the signal I5 has been put in the stop position, or if unable to stop, will run by the signal l5 into the detector track circuit DTC. When the train reaches the detector track circuit, the dropping of the track relay T prevents the operation of the switch machine SM, independently of the control of the relay LR, so that, if the approaching train is unable to stop and runs by the signal I5, the switch can not be operated by power until the train has advanced or backed up clear of this detector track circuit. It will be evident that this time interval should take into consideration the speed of trains on the passing siding PS, the sighting distance of the signal I5, and the braking distance of such trains; and any desired time interval may be employed, as found best adapted to particular operating conditions.

In the case of a normal movement of a train from the passing siding PS, the stick relay S is at once re-energized, without the time interval delay, because the signal I5 automatically assumes the stop position, upon movement of the train thereby, due to the usual track circuit control of this Vsignal (not shown), and with the track relay T de-energized, a pick-up circuit for the stick relay S is established from (-1-), circuit controller 20, wires 25 and 40, back contact il of the track relay T, wires 39 and 30, relay S to Thus, in the case of a normal train movement off of a siding, as soon as the train has cleared the detector track circuit DTC, the switch may be operated, without waiting for the time element device TE to close its contacts 2 I-22. This no-t only saves unnecessary delay in many instances, but also avoids the unnecessary operation of the time element device TE.

From the foregoing, `it can be seen that there is provided by this invention a simple and efcient means for affording the necessary approach locking control of a switch for train movements from passing sidings, branch tracks, or similar stretches of track, which are not equipped with track circuits. It will be evident that the principles and essential features of the invention may be applied to varying conditions encountered in practice, and it should be understood that the .invention is not limited to the particular construction and arrangement of parts shown and described.

What I claim is:-

1. In a system of the type described, the combination with a power operated track switch and a signal governing traflic over the switch, of a stick relaycontrolling the application of power to the switch, a stick circuit for said relay broken when said signal indicates clear, a pick-up circuit for said relay, a thermally actuated time responsive device which when in its active condition closes said pick-up circuit, and an energizing circuit for rendering said time responsivel device active closed only if said stick relay is deenergized and said signal indicates stop.

2. A system of the character described comprising, in combination with a power operated track switch and a signal governing traffic over the switch, of a relay acting while `de-energized to prevent operation of the switch, and an energizing circuit for said relay including the contacts of a thermal element time responsive device, said thermal element of said device being heated when said relay is deenergized and said signal indicates stop.

3. A system for protecting a train moving over power operated switches comprising, a stick relay governing the operation of the switch, a thermal time-responsive device for governing said relay and eiective only if said siding signal is at stop, a main track signal associated with said switch, a siding signal associated with said switch, a detector track relay for controlling the energization of said stick relay independently of said thermal device, a lock relay which if deenergized prevents the-operation of said switch, and a circuit for said lock relay including a front contact of said stick relay and a contact closed only if said main signal is at stop.

4. In combination, a track switch, a signal for governing traflic over said track switch, a lock relay which if deenergized prevents operation of said track switch, a stick relay having a front Contact in the energizing circuit of said lock relay, a thermal relay, a pick-up circuit for said stick relay including a front contact of said thermal relay, and a circuit for the heating coil of said thermal relay including a contact closed when said signal is at stop.

5. In combination, a track switch, a signal for governing trac over said track switch, a lock relay which if deenergized prevents operation of said track switch, a stick relay having a front contact in the energizing circuit of said lock relay, a thermal relay, a pick-up circuit for said stick relay including a front contact of said thermal relay; and a circuit for the heating coil of said thermal relay including a contact closed when said signal is at stop and including a back contact of said stick relay.

Y 6. In combination, a track switch, a signal for governing trailic over said track switch, a lock relay which if deenergized prevents operation of said track switch, a stick relay having a front contact in the energizing circuit of said lock relay, a thermal relay, a pick-up circuit for said stick relay including a front contact of said thermal relay, a circuitl for the heating coil of said thermal relay including a contact closed when said signal is at stop, and a contact open when there is a train approaching said switch included in `the energizing circuit of said lock relay.

said signal is at stop and including a back contact of said stick relay, and a contact open when there is a train approaching said switch included in the energizing circuit of said lock relay.

8. In combination, a stick relay for at times preventing the movement of switch points of a railway track switch, a thermal relay having a normally open contact, an energizing circuit for said thermal relay including a contact closed only when a signal associated with said track switch is at stop and a contact closed when said stick relay assumes its deenergized condition, and a pick-up circuit for said stick relay including said contact of said thermal relay.

9. In combination, a stick lock relay for at times preventing the movement of switch points of a railway track switch, a thermal relay having a normally open contact, an energizing circuit for said thermal relay including ra contact closed only when a signal associated with said track switch is at stop, a pick-up circuit for said lock relay including said contact o f said thermal relay, and

a stick circuit for said lock relay closed only if said signal is at stop.

10. In combination, a lock stick relay for at times preventing the movement of switch points of a railway track switch, a thermal relay having a normally open contact, an energizing circuit for said thermal relay including a contact closed only when a signal associated with said track switch is at stop, a pick-up circuit for said stick lock relay controlled by a contact of said thermal relay, and a stick circuit for said lock relay including a contact open when said signal is cleared.

1l. In combination, a track switch of a railway system, a power operated switch machine for operating said track switch, a signal for governing movement of trailic over said track switch, a stick relay for at times preventing operation of said switch machine and having a stick circuit closed only if said signal is at stop, a thermal relay having a contact open when in its deenergized cool condition, an energizing circuit for said thermal relay including a contact closed only when said signal is at stop, and a pick-up circuit for saidstick relay including said contact of said thermal relay. Y

12. In combination, a track switch of a railway system, a power operated switch machine for operating said track switch, a signal for governing movement of traic over said track switch, a lock stick relay for at times preventing operation of said switch machine and having a stick circuit closed only if said signal is at stop, a thermal relay having a contact open when in its deenergized cool condition, an energizing circuit for said thermal relay including a contact closed only when said signal is at stop, and a pick-up circuit for said lock relay including said contact of said thermal relay.

l3.`In combination, a track switch of a railway system, a power operated switch machine for operating said track switch, a signal for governing movement of traffic over said track switch, a lock stick relay for at times preventing operation of said switch machine, a thermal relay having a contact open when in its deenergized cool condition, an energizing circuit for said thermal relay including a contact closed only when said signal is at stop, a pick-up circuit for said lock relay controlled by a contact of said thermal relay, and a stick circuit for said stick relay controlled by said signal, a lock repeater relay controlled by said stick relay and when deenergized preventing operation of said track switch, said lock repeater relay including a contact open when there is a train approaching said track switch.

lll. In combination, a track switch, a signal for governing trac over said track switch, a lock relay which if deenergized prevents operation of said track switch, a stick relay having a front contact in the energizing circuit of said lock relay, an approach relay having a contact opened when there is a train approaching ineluded in the energizing circuit of said lock relay, a thermal relay, a pick-up circuit for said stick relay including a front contact of said thermal relay, and a circuit for the heating coil of said 'thermal relay including a contact closed when said signal is at stop.

15. In combination, a lock stick relay for at times preventing the movement of switch points of a railway track switch, a thermal relay having a normally open Contact, an energizing circuit for said thermal relay including a contact closed only when a signal associated with said track switch is at stop, a pick-up circuit i'or said lock relay including said contact of said thermal relay, a second pick-up circuit for said stick relay including a back contact of a detector track relay associated with said track switch, and a stick circuit for said lock relay closed only if said signal is at stop.

16. In combination, a track switch capable of setting up a main and a diverging route, a main signal governing traffic over said main route, a diverging route signal for governing traffic over said diverging route, a lock relay for preventing operation of said track switch, a stick relay, a circuit for said lock relay including a front contact of said stick relay and a contact closed only if said main signal is at stop, a. pick-up circuit for said stick relay, thermal relay means for closing said pick-up circuit a predetermined time after said diverging route signal has been put to stop, and a stick circuit for said stick relay broken if said diverging route signal is cleared.

17. A system for protecting trains moving over power-operated track switches comprising, a stick relay which must be energized to permit power operation of a track switch, a signal for governing the movement of traflic over said track switch, an electrically controlled thermal relay the energizing circuit of which may be closed only if said stick relay is deenergized and said signal is at stop and having a contact closed only if said thermal relay has been energized for a predetermined period of time, a pick-up circuit for said stick relay including said contact, a second pick-up circuit for said stick relay including a back contact of a detector track relay associated with said track switch, and a stick circuit for said stick relay including a contact closed only if said signal is at stop.

SEDGWICK N. WIGH'I.

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