US2391976A

US2391976A - Railway switch lock control system

Info

Publication number: US2391976A
Application number: US461677A
Authority: US
Inventors: John J Jacobus
Original assignee: General Railway Signal Co
Current assignee: SPX Corp
Priority date: 1942-10-12
Filing date: 1942-10-12
Publication date: 1946-01-01
Anticipated expiration: 1963-01-01

Description

Jan. 1, 1946. J. J. JACOBUS RAILWAY SWITCH LOCK CONTROL SYSTEM Filed Oct. 12, 1942 2 Sheets-Sheet l Imventor OLPCOU 0 6 CO L00 p U Q mm Jan. 1, 1946.

J. J. JACOBUS RAILWAY SWITCH LOCK CONTROL SYSTEM Filed Oct. 12, 1942 2 Sheets-Sheet 2 5* mi En us co Loco Zhweutor IL. wu M o.5,coU

Patented Jan. 1, 1946 RAILWAY SWITCH LOCK CONTROL SYSTEM John J. J acobus, Town of Greece, N. Y., assignor to General Railway Signal Company, Rochester, N. Y.

Application October 12, 1942, Serial No. 461,677 8 Claims. (01. 246-160) This invention relates to systems for safeguarding traffic on railroads, and more particularl to devices and circuit organizations for protecting hand operated track switches located in the main track lines of railways.

Track switches unlocked and thrown by hand are frequently included in the main track lines of railways for connecting with passing sidings, storage and industrial tracks, and the like; and these switches are operated manually by a trainman from the normal or main track position to a reverse position as occasion may require for train movement into and from the main track. It can be readily appreciated that when a train is ready to come out onto the main track, the hand operated switch should not be thrown if there is some other train on the main track which may pass over the switch points at speed, since a derailment or collision is likely to occur whenever a switch is thrown in, front of a moving train. The general operating rules of the railroads usually require a trainman to have some special authority, such as a written train order, or permission obtained from a dispatcher over the telephone, before operating the switch to come out on the main track; but there isalways the chance for human error in such a procedure so that it is desirable to provide a switch lock and suitable automatic control for preventing hand operation of the switch under unsafe conditions.

In one arrangement of switch locking contemplated in accordance with this invention, the switch lock is provided with approach control, so that the switch points or the hand throw device are positively locked in the normal position if there is any train on the main track within predetermined approach locking limits of the switch. In order to permit operation of the switch for train movement from the main track into the industrial track or the like, a short release track section adjacent the switch is provided to permit release of the switch lock independently of the approach locking control. An arrangement of this character is disclosed, for example, in the prior patent to S. N. Wight, No. 1,476,866, granted December 11, 1923.

In such an approach locking arrangement with track circuit release, the release of the switch lock is effected by the shunting action of the wheels and axles of a train on the release track section when this train is in motion, as well as when it is at rest; and it may happen that a trainman may carelessly operate the switch when the switch lock is thus released by a moving train.

The principal object of the present invention is to provide a special arrangement for the track circuit release of the approach locking for hand operated switches which is effective when a train stops in the release track section and waits for the switch to be'thrown, but is not efiective if a train is moving over the release track section.

Generally speaking, and without attempting to define the nature and scope of the present invention, it is proposed to utilize a time element device in combination with the release track section and an adjoining track section in such a way that release of the switch lock independently of approach locking control occurs only when the release track section has been occupied for a predetermined time while the adjoining track section is not occupied. With this control arrangement, when a train stands in the release track section for the prescribed time without moving in to the adjoining track section, the switch lock is released, and the switch may be operated for this train to move from the main track into an industrial siding or the like; but when the release track section is occupied by a train in motion; such train will necessarily move into the adjoining track section prior to the expiration of the prescribed time interval, and the release of the switch lock is not effective.

Various other characteristic features, attributes and advantages of the invention will be in part apparent and in part pointed out as the description progresses.

In describing the present invention in detail, reference will be made to the accompanying drawings in which corresponding reference characters are used to designate corresponding parts throughout the various figures, in which like letter reference characters are used to designate parts having similar features andfunctions, such parts being generally made distinctive by reason of preceding numerals, and in which: i

Fig. 1 illustrates the present invention embodied in a switch lock control system having approach locking control; and

Fig. 2 illustrates the presentinvention embodied in a switch lock control system employing time release locking instead of the approach control locking of Fig. 1.

The accompanying drawings illustrate in a conventional and diagrammatic manner two specific embodiments of the present invention, the parts and circuits being shown in a manner to facilitate understanding of the functions and operation of the invention, rather than to illustrate the detail structure and arrangement of parts preferably employed in practice. Thus, symbols are employed in the conventional manner for the various devices and sources of electric current instead of showing all of the wiring connections to the terminals of such sources.

The symbols and are therefore emplayed to indicate the connection to the positive and negative terminals respectively of suitable batteries or other sources of direct current, and the circuits with which these symbols are used always have current flowing in the same direction.

The symbols (B+) and (B areus'ed to indicate connections to the opposite terminals of a suitable battery or other direct current source which has a central or intermediate tap designated (C) and the circuits with which these symbols are used may have current flowin in one direction or the other dependent upon the particular (B+) or (B) terminal used in combination with the intermediate tap (C). If alternating current is to be used instead of direct current. the polarity symbols employed are to be considered as instantaneous relative polarities.

The invention may be used in connection with any one of the various appl cations of hand operated switches on both single and double track railways having any suitable form of block Sig-- nalling. with or without supervisory manual control of the si nals and the switch lock by a s stem of central zed trafilc control. In the specific embodiments of the invention shown. it has been assumed for simplicity that the switch lock is applied to a typical outlying switch for the main track of a double track railway equipped with a conventional automatic block signal system using polarized line c rcuits.

Referring to Fig. 1 of the drawings. the move-' ment. of trains on the portion of track shown in the normal direction of traflic from left to right, indicated by the arrow and legend, is governed by signals I. 2, and 3: and the outlying switch W, equipped with a switch lock in accordance with this invention, is located at an intermediate point in the block between signals 2 and 3. This stretch of track is divided by insulated points into track sections AT, IT, IT, etc., in the usual way, each having a track relay. such as ITR. shown conventionally, and a track battery indicated by the symbol B. The signals I, 2, and 3 may be of any suitable type but shown as color light signals, and are arranged to be controlled in accordance with established practice by neutral polar relays HD and polarized line circuits. The relay IHD, for example, which governs the indications of the signal I is energized by a line circuit readily traced on the drawing as including a front contact 5 ofthe track relay ITR for the track section IT of the block in advance of the signal I, so that when this block is occupied the signal control relay I HD is deenergized, and si nal I indicates stop. The polarity of energization of this line circuit for the signal control relay I BI) is governed, in the simplified arrangement shown, by front and back contacts 6 of the signal control relay 2HD for the signal 2 next in advance, so that when this signal 2 indicates stop, the polarity of energization of this line circuit is changed to govern the signal control relay IHD in a manner to cause the signal I to indicate caution. v

In the simplified arrangement shown, the approach control of the switch lock for the switch W is provided by an approach relay A energized by a line circuit including in series the front contacts of the track relays of the track sections included in the approach locking zone. In this connection, it has been assumed that the block in the rear of the signal I is divided into two track sections, so that the approach locking limits extend from switch W to include one track section in the rear of signal I; but obviously these approach locking limits may extend to the signal (not shown) next in the rear of the signal I.

The switch lock controlled in accordance with this invention may be of any suitable manual or power operated type; but in the specific embodiment of the invention shown, it is assumed that this switch lock will be of the electrically controlled and manually released type, such as disclosed for example in the patent to J. E. Stephenson, No. 1,710,668, April 23, 1929. In this type of switch lock, which has been illustrated diagrammatically, a lock dog I0 is raised by the energization of a lock magnet L out of engagement with a shoulder on sector I I, so that this sector, together with an extending arm I2 connected therewith, may be turned by a suitable crank or handle I 4 in the counter-clockwise direction as shown, to lift a locking plunger I5 out of locking engagement in a hole in a lock rod I6 connected to the, switch points. When the locking plunger I5 is raised to the unlocked position, contacts I 1 shown conventionally are opened; and since this locking plunger I5 cannot be again lowered to its locking position to close these contacts I! unless the switch points are in the normal position, these contacts I! will be open while the switch is in the reverse position. Also, associated with the switch W is a suitable switch box or circuit controller having contacts which are closed only when the switch is in a proper normal or reverse position, and this switch box is shown as having contacts I8 closed in the normal position only. For simplicity, these contacts are indicated as operated by lock rod I6, but usually a separate rod is used to connect such contacts with the switch points.

The other elements of the switch lock include a push button PB, a push button repeater stick relay PBS, an indicating lamp 1, contacts D closed when the door (not shown) for the switch lock casing is opened to give access to the operating handle I4 and the push button PB, and also a time element device designated as a whole as TE.

This time element device TE may be of any suitable type and construction capable of being set into operation by electrical control to operate contacts after the lapse of a relatively short time interval, such as 30 seconds. In the arrangement shown, a thermal time element device of the type disclosed, for example, in the patent to J. E. Willing, No. 1,902,793, dated March 21, 1933, has

been diagrammatically illustrated for this purtralized traffic control system, it may be desired to provide manual control of the release of the switch lock from a distant control office, in order to give the dispatcher or operator supervisory control over the hand operated switch, and in particular prevent the switch from being operated for a train to come out onto the main track, even though such train movement may be made with safety, when such movement is contrary to the wishes of th dispatcher, and might otherwise occur due to careless action by a train crew, or perhaps a misunderstanding of the dispatchers instructions over the telephone. In order to illustrate how such supervisory manual control from a distant control office may be employed in connection with this invention if desired, a simplified arrangement for such remote control has been shown diagrammatically as comprising a relay LZ located at the switch adapted to be energized or deenergized over a line circuit by the operationof a suitable control lever LV in the control oflice. It should be understood that this remote control of the switch lock is optional and may be effected in any suitable way, such as by direct line circuits or code type communication systems.

- Referring now to the special track circuit release of the approach locking control for the switch look, there is provided on the facing point side of the switch W a release track section RT having the usual track relay RTR. This release track section is preferably as short as practicable, such as two or three rail lengths, to prevent any release until the train is close to the switch, and yet long enough to enable an approaching train to readily stop in this release track section without overrunning.

Adjoining this release track section RT is another track section, which in the specific arrangement shown is a relatively short detector track section DT of the usual form having a track relay D'I'R.

The organization of this invention also includes a. lock repeating relay LP, which is controlled, in a manner explained more in detail in discussing the operation, to put the signal 2 to stop when either the release track section RT or the detector track section DT is occupied, and certain operations in connection with unlocking the switch have been performed.

Operation (Fig. 1) .The parts and circuits are illustrated in the drawings in the normal condition for the switch locked in the normal position and no trains approaching. Under these normal conditions, the relay LP is energized by a circuit which may be traced from (-1-) through front contact 24 of the detector track relay DTR, back contact 25 of the push button stick relay PBS, front contact 26 of the release track relay RTR, back contact 21 of the lock magnet L, contacts 11 operated by the locking plunger I5, switch box contacts [8, relay LP to The approach relay A is also energized under these normal conditions by a line circuit which may be traced from through the

front contacts

28, 29, 30 and 3| of track relays ATR, ITR, 2TB and RTR respectively.

Assume now that a train on the siding or industrial track desires to operate the switch and come out onto the main track. It is contemplated that a telephone will be provided at the switch to enable the train crew to communicate with the dispatcher and obtain permission to use the switch. Also, if supervisory manual control is provided, the dispatcher will operate the lever IN to energize the relay LZ. Under these conditions with the door of the casing opened to close contacts D, the indicating lamp' I is lighted by a. circuit readily traced from through front contact 33 of relay LZ, door contacts D, front contact 34 of approach relay A, and indicating lamp I, to assuming there is no train within the approach locking limits of the switch and the approach relay A is energized.

When the trainman operates the push button PB, relay PBS is energized by a circuit including the front contact 33 of relay LZ, and the door contacts D; and the energization of this relay closes its front contact 35 to provide a stick circuit to maintain it energized when the push button is released. The energization of the relay PBS and closing of its front contact 25 establishes a circuit for energizing the lock magnet L which may be traced from through the front contact 24 of the detector track relay DTR, front contact 25 of relay PBS, front con tact 36 of approach relay A, and lock magnet L, to This energization of the lock magnet L releases the switch lock, and allows the locking plunger !5 to be manually raised to unlock the switch points and allow them to be operated by the hand-throw device (not shown) provided for this purpose. An indicator 31 is preferably provided, as shown in the Stephenson Patent No. 1,710,668 above mentioned, to show when the switch lock is actually released.

Referring to the circuit above described for energizing relay LP, it can be seen that as soon as the push button relay PBS is energized, this circuit is broken at back contact 25 to release relay LP and open its front contact 38 in the line circuit for signal control relay ZHZD to put the signal 2 at stop and signal I at caution, thereby blocking train movement toward the switch. When the lock magnet L is energized, the opening of its back contact 21 also acts to deenergize relay LP and keep the signal 2 at stop; and the same is true of the contacts I! opened when the locking plunger is in the unlocked position, as well as the switch box contacts it opened when the switch W is reversed. In short, the signal 2 is put to stop, and the signal lin the rear thereof to caution, as soon as a preliminary operation to unlock the switch occurs; and this condition is maintained until the switch is restored to its normal position and locked, the lock magnet L has assumed its normally deenergized position, and the relay PBS has been restored to its normally deenergized position by closing the door to open contacts D, or by deenergization of the relay LZ by the dispatcher.

If, due to some oversight or carelessness on the part of the dispatcher in authorizing operation of the switch, or negligence of the trainman, or for some other reason, an attempt should be made by the trainman to unlock and operate the switch for a train to come out onto the main track at a time when there is some other train on the main track within the approach locking limits, the switch cannot be unlocked because the approach relay A is deenergized. Thus, in spite of some failure of the human element, the switch cannot be unlocked and operated at a time when it may be unsafe to do so on account of an approaching train.

In the organization as illustrated, the switch is kept locked until the train on the main track passes out of the approach locking limits; and this is adequate for the usual outlying switches, since under ordinary operating conditions there is no occasion for a train on the siding to operate the switch and come out onto the main track until the other approaching train on the though some other train is standing or switching within the approach locking limits.

From the foregoing it can be seen that improper operation of the switch is prevented by approach locking control, so that if there should be a train on the main track so close to the switch that it could not stop before reaching the switch in obedience to the stop and caution signal indications displayed when operation of the switch has started, the switch lock is effective to prevent any unlocking of the switch points. In this connection, th approach locking limits are extended in accordance with recognized practice to include at least one track section in the rea" of the second signal governing train movement toward the switch, so that the switch cannot be unlocked while there is a train in position to accept a clear indication of the signal I.

With such approach locking control, it can be readily seen that some special release must be provided to provide a train on the main track to operate the switch to enter the industrial siding or the like; and this special rel-ease is provided by occupancy of the release track section RT adjacent the switch. In order that'such release may not be effective, however, when the release track section is occupied by a moving train, the time element device TE and associated control circuits are provided to perform the functions in accordance with this invention.

Considering this releasing operation, assume a train pulls up to the switch W into the release track section RT, and then the relay PBS is energized in the same manner above explained. Under these conditions, the approach relay A is deenergized, and the energizing circuit for the lock magnet L above described is open at front contact 35. The heating coil 20 of the thermal element is energized by a circuit which may be traced from through front contact 24 of the detector track relay DTR, front contact 25 of relay PBS, back contact 45 of release track relay RTR., back contact 4! of relay RS, heating coil 20, to After a predetermined time interval, such as 15 seconds, this flow of current through the heating coil 25 causes the thermal device to open the normally closed contacts 22 and close the contacts 2 1, thereby energizing the relay RS over the same circuit above traced in multiple with the heating coil 25. The energization of relay RS breaks at its back contact 4| the circuit through the heating coil and closes through its front contact 4! a stick circuit maintaining this relay energized independently of the contacts 21. When the thermal device cools to its normal condition and the normally closed contacts 22 again close, the energizing circuitfor the lock magnet L is established through the

front contacts

24 and 25 of relays DTR and PBS, back contact 49 of relay RTR., normally closed contacts 22 of thermal element, and front contact 42 of relay RS. p-

In this way, the switch lock is released after a relatively short time interval such as 30 seconds, when a train stops in the release track section RT; and the switch may be thrown for this train to enter the associated siding or track.

If for some reason a trainman should attempt to obtain release of the switch lock for a train movement onto the main track, while some other train is moving over the release track section RT, the release will not occur, because the moving train after entering the release track section RT and closing back contact 40 of track relay RTR to initiate operation of the time element device TE, will necessarily advance into the adjoining detector track section DT prior to the expiration of the prescribed time interval, and by opening front contact 24 of the detector track relay DTR, will stop further operation of the time element device and also open the energizing circuit for the lock magnet L. In other words, a train standing in the release track section RT for a relatively short prescribed time, subsequent to a manual control to initiate unlocking operation, will give a release of the switch look, while occupancy of this release track section by a train in motion will not release the switch look. This aflords additional safety in the track circuit release of an approach locking arrangement for switch locks, since the switch lock cannot be released and the switch operated in the face of a moving train, it the trainman should be so negligent as to attempt to do so. The detector track section DT also prevents release of the switch look while a train is standing or moving over the switch points.

It will be noted that the provision of the indicator lamp I advises the trainman at the switch W whether or not a train is approaching provided the relay LZ has been energized. If the operator in the control oflice has perchance ill-advisedly given the release or has failed to restore lever LV after the passage of some other train, the trainman at the switch will not operate the push button PB and thus cause the picking up of the relay PBS resulting in putting the signals to stop in the face of the oncoming train. In other words, the ind cator lamp I provides means in combination with the use of the push button PB to prevent the signals ill-advisedly being placed at stop merely by the opening of the switch lock door.

With reference to Fig. 2 of the drawings, the present invention has been shown applied to an organization where the approach locking control is replaced by time release locking. It will be noted that the same reference characters have been given to the devices in Fig. 2 corresponding to the devices of Fig. 1. Thus, it will be clear that the approach relay A of Fig. 1 has been omitted and in its place, is a slow-acting timing device STD which is controlled by the door repeating relay DRP through its front contact 45 and by front contact 46 of the release section track relay RTR. This slow-acting timing device STD may be of any suitable type which will measure off a predetermined time before closing its contacts, such as contact 48, upon the energization of its operating windings. This device may be such as shown for example in the Patent No. 2,199.335. granted to O. S. Field, April 30, 1940, or maybe a thermal relay and an associated repeating relay, or any other suitable organization for timing a relatively long time such as for example 4 to 6 minutes.

Operation (Fig. 2) .Assuming that a train is on the industrial track and desires to manually operate the track switch W to a reversed position to enter the main track, a trainman opens the door lay DTR, front contact 41 of the door repeating,

of the switch lock closing the contacts D. He then calls the operator in the control ofiice, and if traflic conditions are proper, the operator in the control office actuates the lever LV and energizes the relay LZ closing front contact 49 and energizing the door repeating relay DRP. This closes front contact 45 of relay DRP energizing the slow-acting timing device STD and immediately opening back contact 44 (a checking contact which is not again closed until the timing device STD is deenergized and restored to normal conditions). At this time back contact 41 of relay DRP is also open so that relay LP is deenergized opening front contact 38 placing signal 2 at stop and signal I at caution in a manner described in connection with Fig. 1. After a predetermined time has elapsed, the slow-acting timing device STD closes its front contact 48 permitting an energizing circuit to be closed for the lock magnet L from through a circuit including front contact 24 of detector track relay DTR, front contact 41 of relay DRP, front contact 48 of the slow-acting timing device STD, windings of the lock magnet L, to

This releases the look so that the trainman may actuate handle 14 in a counter-clockwise direction to release the switch lock and permit hand operation of the switch W to its reversed position.

It will be appreciated that the switch W is not released until a predetermined time after the signals have been placed to stop which time is contemplated as being sufficient for any approaching train to either stop short of signal 2 at stop or to reach the detector track section DT and r y rgize the track relay DTR opening front contact 24 and positively prevent the release of the switch lock. In this way, protection is provided against the unsafe operation of the switch W to a reverse position should the operator in the control ofiice ill-advisedly permit the energization of the relay LZ.

After the train has passed onto the main track, the trainman must, of course, restore the switch W to its normal position and replace the lock handle 14 in its normal locking position before leaving the switch, it being understood that the handle I 4 of the switch lock cannot be replaced unless the switch W is in a proper normal position.

We may now consider the approach of a train in an eastbound direction over the main track which train is to enter the industrial turnout track by reversing the switch W. Such train comes to stop on the release track section RT and a trainman proceeds to open the door of the switch lock and communicates with the control ofilce the same as before. The control office operator then gives permission for the switch to be unlocked by energizing the relay L2, and this energizes the door repeating relay DRP. But in this case, the open condition of front contact 46 of the track relay for the release track section prevents the operation of the slow-acting time device STD, while the closure of back contact 49 causes the time element TE to be immediately set into operation by a circuit including front contact 24 of relay DTR, front contact 41 of relay DRP, back contact 40 of relay RTR, back contact 4!, thermal coil 20. The time device TE operates as previously described.

After the relatively short time of 30 seconds for example, the circuit for the release of the lock magnet L is completed from through a circuit including front contact '24 of detectorrerelay DRP, back contact 40 of relay R'IR, normally closed contact 22 of the thermal relay, front contact 42 of relay RS, windings of the lock magnet L, to This permits the switch lock to be released by. operation of the lever 14 and the trainman moves the switch W to its reversed position to allow the passage of the train. After the passage of the train, the trainman restores the switch W to its normal locked condition closing the door of the switch lock, and thus the signalling system is restored to the condition for following train movements in the usual manner.

The provision of the time element TE in such a system provides that the release track section RTR in eliminating the relatively long time of the slow-acting timing device STD for trains entering the turn-out track does not permit the quick release of the switch lock and operation of the switch W in the face of a moving train. In other words, the time element TE in this form of the invention provides that a train moving over the main track and onto the release track section RT while some trainman is endeavoring to obtain a release of the switch lock, will not permit release of the lock by closure of back contact 49 before the train occupies the detector track section and opens contact 24 to positively prevent the release of the switch lock. The sys- 'tem thus provides additional safety since the switch cannot be released and manually operated in the face of a moving train on the release section, should a trainman be so negligent as to attempt to do so.

The specific embodiment of the invention shown and described is merely a typical example of a construction and arrangement of parts and circuits suitable for accomplishing the desired functions; and I desire to have it understood that various modifications, adaptations, and additions may be made in this particular embodiment without departing from the invention.

What I claim is:

1. In a switch lock control system, a hand operated track switch remote from a control office, an electric switch lock normally efiective to prevent hand operation of said switch, a signal for governing trafiic over said switch, a relatively short release track section in a facing point position with respect to said switch, contact means at the switch manually controlled to open and closed positions from said remote control oflice, other contact means at the switch manually operated locally to open and closed positions, electroresponsive means energized only when both of said contact means have been operated to closed positions, means for causing said signal to display stop whenever said electroresponsive means-is energized, electric timing means, circuit means rendered efiective when said electroresponsive means is energized and said release track section is 00- cupied by a train to initiate operation of said timing means, releasing circuit means acting when said timing means has measured a predetermined time to release said electric switch lock, and other circuit means at times rendered effective by the energization of said electroresponsive means for releasing said electric switch look when said release track section is not occupied by a train.

2. In a switch lock control system, a hand operated track switch remote from a control ofilce, an electric switch lock normally effective to prevent hand operation of said switch, a distant signal for governing traffic toward said switch in a facing point direction, a detector track section associated with said switch, a relatively short release track section between said switch and said si nal, manually controllable means rendered active in response to joint manual control by a trainman at said switch and an operator at the control ofiice, said manually controllable means effective when rendered activ to cause said signal to display stop, electric circuit means governed by said manually controllable means for immediately releasing said electric switch lock if there is no train approaching said switch and said detector track section is unoccupied, and other electric circuit means governed by said manually controllable means in an active condition to release said electric switch lock when a train is in approach to said switch providing said release track section is occupied by a trainfor a predetermined time and said detector track section is unoccupied, whereby a train standing On said release track section permits the manual release of said switch look while a moving train is ineffective to permit a release.

3. In an electric switch lock control system, a hand operated track switch remote from a control ofiice, an electric lock normally eifective to prevent hand operation f said switch, a signal for governing traific over said switch, a detector track section associated with said switch, a relatively short release track section in a facing point position with respect to said switch, electroresponsive means initially rendered active in response to joint manual control by a trainman at the switch and an operator at the remote control ofiice, means for causing said signal to display stop whenever said electroresponsive means is rendered active, electric timing means, circuit means rendered efiective when said electroresponsive means is rendered active and said release track section is occupied by a train to initiate operation of said timing means, said circuit means also acting when said timing means has measured predetermined time to release said electric switch lock, approach controlled circuit means efiective providing there is no train in approach to said switch for releasing said electric switch lock independently of said timing means, and contact means for acting on both said circuit means to prevent the release of said electric look while said detractor track section is occupied by a train.

4. In an electric switch lock control system, a hand operated track switch remote from a control oifice, an electric lock normally effective to prevent hand operation of said track switch, a signal for governing traific over said track switch, a relatively short release track section in a facing point position with respect to said switch, manually controllable means rendered active in response to joint manual control by a trainman at the switch and an operator at the control office, said manually controllable means being effective when rendered active to cause said signal to display stop, electric circuit means governed by said manually controllable means when rendered active for immediately releasing said electric switch lock if there is no train approaching said switch, other electric circuit means governed by said manually controllable means to releasesaid electric switch look when a train is in approach to said switch providing it occupies said release track section for a predetermined time, and an indicator governed in accordance with approaching traflic to indicate when said switch lock can be immediately released by said manually controllable means.

5. In a switch lock control system, a hand operated track switch remote from a control ofllce, an electrical switch lock normally effective to prevent hand operation of said switch, a relatively short release track section in a facing point position with respect to said track switch, a detector track section associated with said track,

switch, a first time measuring means effective when initiated into operation to measure a relatively long predetermined time, a second time measuring means effective when initiated into operation to measure a relatively short predetermined time, electroresponsive means adjacent the track switch energized in response to joint man-x ual control by a, trainman at the switch and an operator at the remote control office, means controlled by the presence or absence of a train in said release track section to respectively determine whether said second or first time measuring means shall be initiated into operation in response to the energization of said electroresponsive means, and means for releasing said electric vice, track circuit means responsive to the presence of a train in approach to said switch for governing the initiation of the operation of said time element device and also governing the stop indication of said signal, a manually operable contact located adjacent to said switch and normally in its open position, a circuit including said time element contacts and said manually operable contact for energizing said lock relay to'permit hand operation of said switch, and means associated with said switch lock for maintaining said signal at stop while said lock relay is energized or said switch is not locked in its normal position. I

7. In a system for governing the release of switch locks for outlying hand-thrown track switches on railroads, the combination with a hand-thrown switch in a stretch of track, of a switch lock for locking said switch against movement in the normal position only, a normally deenergized lock relay acting when energized to govern the release of said switch look, a release track section located adjacent said switch and having a track relay, a signal governing train movement in one direction over the stretch of track and over said switch, circuit means for governing the indications of said signal and efs fective to provide a restrictive indication of said signal if said switch lock is released or said release track section is occupied, an electrically operable time element device located at the switch for closing normally open contacts only if said device has been operated for a predetermined time, a circuit including said contacts of said time element device for causing energization of said lock relay to permit hand oper-,

ation of the switch for train movement from the stretch of track over the switch in a reverse position, and circuit means governed by the track; relay of said release track sectionfor c'on trolling the initiation of the operation of said time element device while a train occupies said track section, whereby said switch lock may be released for a train to enter the switch by reason of the fact that such train comes to a stop and occupies the release track section long enough for the time element device to operate.

8. In a system for governing the release of a switch lock for outlying track switches on railroads, the combination with a hand-thrown track switch and a switch lock therefor including a lock relay for governing the release of said switch look, a signal tor governing train movement over said switch in one direction, a control circuit for said signal effective only if closed to govern the clearing of said signal, a release track section adjacent said switch on the facing point side, another track section adjoining said release track section and including said track switch, an electrically operable time element device located at the switch and having contacts closed only when said time element device has been operated for a predetermined time, an

energizing circuit for said lock relay oi the switch lock including said contacts pf said time element device, means acting in response to the presence of the wheels and axles of a train in said track sections for opening said control circuit for said signal when either of said track sections is cocupied, and means manually conditioned for operating said time element device only while a train approaching the switch occupies said release track section without entering said another 7 adjoining track section, whereby said switch lock may be released when a train enters said release track section provided that train comes to a stop and occupies that track section long enough for said time element to operate to close its contacts, and whereby said switch lock is not released by the presence of a train entering said release track section for a through train movement provided said last mentioned train enters said adjoining section prior to the expiration of said predetermined time.

JOHN J. JACOBUS.