US2092197A - Interlocking control apparatus - Google Patents

Description

Sept. 7, 193 7.

E. M. ALLEN ET AL 2,092,197 INTERLQCKING CONTROL APPARATUS Filed July 31, 1935 I I W FLIO Fly 2 INVENTOR S EarlMflLLew and,

2 nrj/ 5. Yo 21mg.

THEI R ATTORNEY Patented Sept. 7, 1937 STATES PATENT OFFICE W'ilkinsburg, Pa.,

assignors to The Union Switch & Signal Company, Swissvale, Pa, a corporation oi Pennsylvania Application July 31, 1935, Serial No. 34,040

16 Claims.

Our invention relates to interlocking control apparatus for railway track switches and signals in a railway switching or interlocking layout.

One feature of our invention is the provision of means for safeguarding the operation of the apparatus after a switch has been irregularly operated as, for example, by hand.

The apparatus of our invention is an improvement over that disclosed in the copending applications Serial No. 125,659, filed July 29, 1926, by Herbert A. Wallace for Railway trafiic controlling apparatus; Serial No. 313,772, filed October 29, 1928, by Howard A, Thompson for Multiple control apparatus; Serial No. 379,163, filed July 1S, 1929, by Charles A. Brooks for Multiple control apparatus; Serial No. 505,328, filed December 29, 1930, by Allen, Brooks and Thompson for Railway trafiic controlling apparatus; Serial No. 416,061, filed December 23, 1929, by Howard A. Thompson for Multiple control apparatus; Serial No. 653,023, filed January 23, 1933, by Harry C. Vantassel for Remote control systems; and Serial No. 695,294, filed October 26, 1933, by Allen and Thompson for Interlocking control apparatus.

We will describe two forms of apparatus embodying our invention, and will then point out the'novel features thereof in claims.

In the accompanying drawing, Fig. l is a diagrammatic view showing one form of apparatus embodying our invention, in which a switch is operated by an electric motor. Fig. 2 shows a modification of this form of apparatus, also embodying our invention, in which a switch is operated by a motor of the fluid pressure type.

Similar reference characters refer to similar parts in each of the views.

Referring first to Fig. 1, the reference charac ters i and i designate the track rails of a stretch of railway track Y, which is divided by insulated joints 2 into sections B-C and CD. Each of these sections is provided with a. track circuit comprising a battery 3 connected across the rails adjacent one. end of the section, and a track relay designated by the reference character T with a distinguisrnng exponent connected across the rails adjacent the opposite end of the section.

Located in section C-D, is a switch W for connecting track Y with a second track Z. Switch W is operated by an electric motor G which is governed by a control device F. Motor G comprises an armature t and a field winding 6.

A contact 5 is shown in the motor circuit adjacent the field winding 6. This contact may be manually opened in order to deenergize motor G when it is desired to move switch W by hand.

At point C, a signal S is shown for governing eastbound traffic movements, that is, tramc movements from left to right, as shown in the drawing, over switch W in the normal position in which it is shown. A second signal S is also shown for governing eastbound traffic movements over switch W in the reverse position to track Z. Signals S and S operate contacts l'i and i8, respectively, each of which is closed only when the corresponding signal is indicating stop. Both of the signals S, as here shown, are of the semaphore type. They may be of any other suitable construction.

Control device F is controlled by pole-changing contacts 7 and 8 of a lever relay 1;, if a stick locking relay L is energized. Control device F is controlled by a polar contact 9 of a polarized switch indicating relay K, if locking relay L is deenergized.

Lever relay 1) is controlled by a contact 33 of a switch lever V Lever V has two positions, that is, a normal position 11. and a reverse position 7. Its contact 33 is closed only when lever V is in the r position.

Lock relay L is controlled by switch indication relay K, by lever relay 1), by track relay T and by an approach locking relay P.

An indicator which is here shown as a lamp e is controlled by relays K and L.

Approach locking relay P is controlled by sig nal contacts I1 and N, by track relays T, and by a thermal relay R. Thermal relay R comprises a heater element 23, and a contact 22 which closes only after element 23 has been energized for approximately a given period of time. Thermal relay R is controlled by signal contacts I? and H3, and by a back contact 2| of relay P.

Switch indication relay K is controlled by relay L, and by pole-changing contacts 29 and 32 which are operated by switch W.

Each of the signals S is controlled by a relay which is designated by the reference character H with an exponent corresponding to that of its signal, and by a signal lever V Lever V has a. normal position m, and a reverse position 1' for controlling signals S and S and may also have a reverse position n to the left for controlling signals for the opposite direction of trafiic movements over switch W. Contact 34 of lever V for controlling signals S and S, is closed only when lever V is moved to its 1 position.

Each of the relays H is controlled by lever iii relay 1) when relay L is energized, and is controlled by relay K when relay L is deenergized.

Relay H is also controlled by relay K energized in the normal direction, and relay H is contact numbers comprises the reference character and exponent of the device by which it is operated. For example, the exponent K, for contact 9 shown in the circuits for relay L, comprises the reference character K for switch indie cation relay K which operates contact 9 Similarly, exponent T for contact Zii in the circuits for relay L, comprises the reference character T and its exponent 2 for track relay T which operates contact 26".

In Fig. 2, switch W is shown operated by a fluid pressure mechanism M. This mechanism is controlled by normal and reverse magnets 1m and Tr, respectively.

Normal magnet 1m is controlled by a back contact of relay 1; when relay L is energized, and is controlled by a normal contact of relay K when relay L is deenergized. Reverse magnet T1 is controlled by a front contact of relay 1) when relay L is energized, and is controlled by a reverse contact of relay K when relay L is cleenergized.

As shown in the drawing, all parts are in the normal condition, that is, track relays T and T are energized; switch lever V is in its normal position 71; signal lever V is in its normal position m; switch W is in its normal position; signals S and S are indicating stop; relays H, K, P and L are energized; relays H '0 and R are deenergized; and indicator lamp c is deenergized.

We will first trace the operation of the form of apparatus shownv in Fig. 1.

With signals S indicating stop, and with relay T energized, a pickup circuit is closed for energizing relay P, passing from the terminal r of a suitablesource of current not shown in the drawing, through contacts H and B8 of signals S" and S respectively, contact 26 of relay T and the winding of relay P to terminal of the same source of current. A stick circuit is also closed for relay P, and is the same as the pickup circuit just traced except that it includes the front point of contact 2! of relay P instead of contact 26 of relay T A pick-up circuit for relay L is closed, passing I from terminal as, through contact 9 in its normal position, back point of contact 2% of relay 0, contacts 25 and 2W and the winding of relay L to terminal 0. A stick circuit is also closed for relay L, passing from terminal at, through the front point of contact 21 of relay L, contacts 25 and 26 and the winding of relay L to terminal 0.

'Switch control device F is energized in the normal direction by a circuit passing from terminal :0, through the back point of contact I of relay 1), front point of contact iii of relay L, device F, front point of contact 93 of relay L, and the back point of contact 8 of relay 1) to terminal o.

A pick-up circuit for energizing switch indication relay K by current of normal polarity is closed, passing from terminal :c, through contact 29 of switch W in the normal position, winding of relay K, contact BI and contact 32 of switch W in the normal position, to terminal 0. Astick circuit is also closed for relay K, which is the same as the pick-up circuit just traced except that it includes contact 3G) of relay K instead of contact 35 Signal relay H is energized by its circuit passing from terminal as, through the back point of contact 7 of relay 1), front point of contact iii of relay L, contact l l of relay K in its normal position, contact i2 of relay K, and the winding of relay H to terminal 0.

We will assume that, with all parts of the apparatus of Fig. 1 thus in their normal condition, the leverman desires to clear signal S 'to permit a traific movement to be made along track Y over switch W in the normal position. He will therefore move lever V to its 7* position, thus completing a circuit for operating signal S to the clear position, this circuit passing from terminal ac, through contact 34 of lever V contact 35 of relay H and the mechanism of signal S to terminal 0.

Signal S upon being operated to the clear position, opens its contact ll, thereby deenergizing approach locking relay P. Relay P, upon becoming deenergized, permits its contact 25 to open and thereby deenergize relay L. Contact M will therefore open the pick-up circuit for relay K which will, however, remain energized by its stick circuit.

Upon the deenergization of relay L, contact El of this relay will close at its back point, thereby completing a circuit for energizing indicator e, this circuit passing from terminal :r, through the back point of contact M of relay L, front point of contact 28 and indicator 6 to terminal 0.

With relay L deenergized, the circuit previously traced for switch control device F will be open at the front points of contacts H3 and it of relay L, and a second circuit will now be co 1- pleted for energizing device F in the normal direction, this circuit passing from terminal :13, through contact 9 in the normal position, back point of contact Ill of relay L, device F, contact M of relay K in the normal position, and contact IS to terminal 0.

When the lcverman desires to return signal S to the stop position, he will return lever V to its m position, thereby deenergizing the mechanism of signal S approach section BC, relay P will become energized by its pick-up circuit previously traced.

If, however, there is a train in section B C, causing relay T to be deenergized, thermal relay R will become energized by its circuit passing from terminal :0, through contacts ill and it of signals S and 8*, respectively, back point of contact 2| of relay P, and heater element of relay R to terminal 0. Upon the lapse of the necessary period of time, contact 22 of relay R will close,-

and relay P will then become energized by a second pick-up circuit which is the same as the pick-up circuit previously traced, except that it includes contact 22 of relay R instead of contact 26 of relay T If the leverman does not return lever V to its m position until a train has passed signal S and occupies detector section C-D, relay P will then become energized by a third pick-up circuit which is the same as the pick-up circuit first traced,

If at this time there is no train on g 2,092,197 I except that it includes contact IQ of relay '1 instead of contact 20 of relay T We will next assume that, with all parts of the apparatus again in normal condition, the leverman desires to reverse switch W. He will therefore move lever V to its 1' position, thus causing relay 1) to become energized by its circuit which includes contact 33 of lever V With relay energized, switch control device F will become energized by a reverse circuit which is the same as the normal circuit first traced, except including the front points of contacts I and 8 of relay 1) instead of the back points of these contacts. With device F thus energized by current of reverse polarity, motor G will move switch W to its reverse position.

Relay K will become deenergized by the opening of switch contacts 29 and 32 during this movement of switch W. When switch W reaches its reverse position, relay K will become energized by current of reverse polarity through a reverse pick-up circuit which is the same as the normal pick-up circuit previously traced for relay K. ex-

,cept including contacts 29 and 32 of switch W current, through the back point of contact 28 and indicator e to terminal 0 which is common to both sources of current. The second source of current may be arranged to supply current of a slow pulsating characteristic in order to give a distinctive blinking indication by lamp e.

With relay o energized, and with relay K energized by current of reverse polarity, relay H will be deenergized, and relay H will be energized by its circuit passing from terminal 3:, through the front point of contact 8 of relay 1:, front point of contact N3 of relay L, contact M of relay K in its reverse position, contact l5 of relay K, and the winding of relay I-I to terminal 0.

When the leverman desires to return switch W to its normal position, he will return lever V to its n position, thereby deenergizing relay '0 and causing the normal control circuit for device F to be completed, as previously traced, through the back points of contacts 1 and 8 of relay 1). Switch indication relay K will become deenergized during the movement of switch W to its normal position, and, upon the completion of the movement of switch W to its normal position, will become energized by current of normal polarity in its pick-up circuit first described.

We will now assume that, with all parts again in the normal condition, the leverman clears signal S as previously described. We will also assume that while signal S is clear, the maintainer, in order to do some work on the switch, or for some other reason, opens manual contact 5 at motor G and manually reverses switch W. Contacts 29 and 32 of switch W, being of the usual and well-known switch indication type which will open as soon as the operation of unlocking the switch-and-lock movement of switch W is begun, will cause relay K to be deenergized at the beginning of the unlocking operation of switch W, and will thus cause relay I-I to be deenergized before the movement of switch W is begun. With relay H deenergized, the arm of signal S will return to its stop position.

If there is no train on approach section BC, relay P will become energized by its pick-up circuit first traced, as soon as contact I! of signal S closes. With relay P energized, relay L will become energized by its pick-up circuit previously traced. With relay L energized, relay K will become energized, in the reverse direction, by the second pick-up circuit previously described for this relay, as soon as switch W occupies its reverse position and is locked in that position. Relay L will now remain energized by its stick circuit. Although relay K is energized in its reverse direction, relay 1) is deenergized, and hence signal relay H will not become energized.

As soon as the maintainer is through working at switch W and closes contact 5, control device F, being energized by its normal control circuit first traced, will cause motor G to return switch W to its normal position. During this operation of switch W, relay L will remain energized by its stick circuit previously traced, and hence relay K will again become energized in the normal directicn as soon as the movement of switch W to its normal position and the locking of switch W in that position have been completed. Signal control relay H will then become energized by its circuit previously traced, thereby causing signal S to be returned to its clear position.

It follows that, without any action by the leverman, switch W and signal S will be returned, after the maintainer again closes contact 5, to the condition in which they agree with the positions of levers V and V as previously set by the leverman.

We will next assume that all parts are again in the normal condition, and that the leverman again clears signal S as previously described. We will further assume that an eastbound train enters section BC, and that the maintainer then places signal S in its stop position by opening contact 5 at switch motor G, but that before relay P has had time to become energized by its circuit which includes contact 22 of relay R, the maintainer again closes contact 5. When relay P deenergized, relay L will also be deenergized, and hence relay K cannot become energized.

The second normal control circuit will therefore be completed for switch control device F, passing from terminal 11:, through contact 9 in its normal position, back point of contact IU of relay L, control device F, contact IA of relay K in its normal position, and contact IS to terminal 0. With control device F thus energized by current of normal polarity, motor G will return switch W to its normal position, if the maintainer has moved it away from there.

As soon as relay P has become energized by its second pick-up circuit including contact 22 of thermal relay R, relay L will become energized by its pick-up circuit first traced. With relay L energized, relay K will become energized by its normal pick-up circuit previously traced. With relay K energized in the normal direction, and with relay L energized, relay I-I will again become energized by its circuit first traced, thereupon causing the arm of signal S to be operated to its clear position.

We will now assume that, with switch W again in its normal position and with signal S in its clear position, the maintainer, after an eastbound train enters section BC, again opens contact 5 at motor G and reverses switch W by hand, as previously described. Relay K will become deenergized during this operation of switch W, and will remain deenergized until relay L again becomes energized. We will further assume that, while contact 5 is open and before relay P has become energized, the leverman reverses switch lever V thereby causing relay u to become energized as previously described.

As soon as relay P has become energized on 'account'of signal S being returned to its stop position, contact 25 in the pick-up circuits for relay L will become closed, but the pick-up circuit first traced for relay L will be open at the back point of contact 24 of relay '0, and a second pickup circuit for relay L will be .open at the reverse point of contact 3 since relay K has not yet become energized. Signal relays H are controlled in part by front contacts of relay K, and hence neithe" of the signals S can be cleared until relay K is again energized. Signal S will therefore remain in the stop position, although lever V and switch W now occupy corresponding positions.

With relay L deenergized, and with the polar contacts of relay K still in their normal positions, control device F will now be energized in the normal direction by its circuit previously traced through contact 9 in its normal position, and back point of contact IU- of relay L. Hence, as soon as the maintainer closes contact 5 at motor G, switch W will be returned to its normal position.

Relay L will still be deenergized if relay u is still energized. In order to close a pick-up circuit for relay L, which in turn controls the pick-up circuits for relay K, the leverman must return lever V to its normal position, thereby deenergizing relay 1; and causing relay L to become energized by its pick-up, circuit previously traced. Therefore, although switch W is returned to its normal position, signal S will not clear until lever W is returned to its normal position. Also, it follows that storage of control of switch W by lever V is prevented if the condition of relay 1) is changed while relay L is deenergized.

We will now assume that all parts of the apparatus are again returned to the normal condition,

and that the leverman again clears signal S as previously described. We will further assume that an intermittent shunt or open circuit occurs in the circuit for switch indication relay K, causing relay K to; be intermittently deenergized.

On account of signal S having been cleared, relay P will be deenergized, and hence relay L will be deenergized.

As soon as relay K becomes deenergized by the intermittent shunt or open circuit just referred to, contact E2 of relay K will open, causing relay I-I to be deenergized, which in turn will cause the arm of signal S to be returned to the stop position. If train is on. approach section B-C, relay P will not become energized until relay R has had time to close its contact 22 by the circuit previously described. As soon as relay P becomes energized, relay L will become energized, and hence relay K will become energized. As soon as relay K becomes energized, signal relay H will become energized, and hence the arm of signal S will again be returned to the clear position.

As soon as relay K is next deenergized by the intermittent shunt or open circuit, relay I-I will again be deenergized and signal S will again be returned to the stop position. The circuit for energizing heater element 23 of thermal relay R will therefore again be completed, and after another period of time sufiicient for relay R. to close its contact 22, relay P will again become energized, causing relay L to be energized, which in turn causes relay K to also be energized. With relay K again energized, relay H will again be energized, causing the arm of signal S to again be operated to the proceed position.

It follows that, with relay K controlled by relay L, which is in turn controlled by relay P as shown in the accompanying drawing, the bobbing of the signals due to an intermittent shunt or open circuit in the control for relay K will be much less than if relay K were controlled only by switch W. In the apparatus modified as shown in Fig. 2, relays K and L are energized as described in connection with Fig. 1. Normal control magnet m2 is energized by a circuit passing from terminal as, through the back point of contact 37 of relay 1;, front point of contact i3 of relay L, and the winding of magnet "rm to terminal'o. Signal relay H is also energized by its circuit, passing from terminal 9:, through the back point of contact 37?.

of relay 1;, front point of contact E3 of relay L, contacts 38 and i2 ofrelay K, and the winding of relay H to terminal o. i w

If the leverman now clears'signal S by moving lever V5 to its r position as described in connection with Fig. l, relay P will become deenergized due to the opening of contact ll of signal S With. relay P deenergized, relay L will also be deenergized, thereby completing a second circuit for magnet 1m, passing from terminal :1:, through contact 9 in its normal position, back point of contact E3 of relay L, and the winding of'magnet 1m to terminal o. A second circuit will also be completed for relay H passing from terminal 1', through contact 9 in its normal position, back point of contact E3 of relay L, contacts 3?; and E2 of relay K, and the winding of relay H to terminal o a We will assume that all parts of the apparatus are returned to their normal condition, and that the leverman then proceeds to reverse switch W by reversing switch lever V and thereby energizing relay 1:. With relay o energized, a circuit will be completed for energizing reverse magnet T7, this circuit passing from terminal at, through the front point of contact 3? of relay 1;, front point of contact it of relay L, and the winding of magnet rr to terminal 0. Mechanism M will therefore reverse switch W.

Upon the completion of 'theoperation and looking of switch W, relay K will'become energized by its reverse circuit previously described in connection with Fig. 1. With relay K energized in the reverse direction, relay H ,will become energized by its circuit passing from terminal 3:, through the front point of contact 37 of relay 1), front point of contact it of relay L, contacts 39 and 15 of relay K, and the winding of relay H to terminal 0.

If the maintainer opens the circuits for magnets nn and T7 in some manner, such for example as by removing the control wires for these magnets from the terminal posts of the magnets, the operation of the apparatus will be similar to that described in connection with Fig. 1 when the maintainer opens contact 5 adjacent motor G, and will therefore be readily understood by reference to the drawing, without further detail description.

From the foregoing description and the accompanying drawing, it follows that in apparatus embodying our invention:

A. If a maintainer opens the control or operating circuits for a switch While a signal governing traffic movements over the switch is clear, and if the maintainer then moves the switch by hand, the signal will be put to stop as soon as the unlocking operation of the switch has begun, and all signals governing traffic movements over the switch will remain at stop after the switch has been reversed.

B. If the maintainer moves the switch to a new position by hand, causing a signal governing trafiic movements over the switch to be placed in the stop position, and if the leverman then changes the position of the switch lever to agree with that of the switch, the signal for governing trafiic movements over the switch in the new position will not clear, although the position of the switch agrees with the position of its lever.

C. If, after the maintainer opens the circuits for a switch and moves the switch by hand, the leverman makes no change in the position of the levers, and if the maintainer then again closes the switch circuits, the switch and signal will be automatically returned to the condition in which they were before the leverman reversed the switch by hand.

D. In the event of intermittent shunts or open circuits in the control circuits for the switch indication relay K, the signal will be placed in the stop position, and will not again clear until the period of time necessary for the energization of the approach locking relay through its time element device has elapsed. The pumping action of the signal is therefore reduced, since the signal will clear only as often as the approach locking relay can become energized by means of its time element device.

E. An indicator is provided, which becomes energized if either the switch indication relay K or the auxiliary locking relay L is deenergized.

Although we have herein shown and described only two forms of interlocking control apparatus embodying our invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of our invention.

Having thus described our invention, what we claim is:

1. In combination, a stretch of railway track including a switch, a locking stick relay, a manually controllable switch lever having a normal and a reverse position, a pick-up circuit for said stick relay controlled by trafiic conditions in said stretch and closed only if said lever is in its reverse position while said switch is in its reverse position, a second pick-up circuit for said stick relay controlled by traffic conditions in said stretch and closed only if said lever is in a position other than its reverse position while said switch is in its normal position, a stick circuit for said stick relay controlled by trafiic conditions in said stretch, normal and reverse switch control circuits controlled by said lever and by said stick relay in its energized condition for effecting operation of said switch to its normal and reverse positions, and normal and reverse control circuits for said switch controlled by said switch and by said stick relay in its deenergized condition for retaining said switch in its normal and reverse positions respectively or for restoring said switch to those positions.

2. In combination, a stretch of railway track including a switch, a stick locking relay, a manually controllable device having a normal and a reverse position, a pick-up circuit for said stick relay controlled by said device and by said switch and closed if said device is in its reverse position while said switch is in its reverse position, a second pick-up circuit for said stick relay controlled by said device and by said switch and closed if said device is in a position other than its reverse position while said switch is in its normal position, a stick circuit for said stick relay controlled by traffic conditions in said stretch, normal and reverse switch control circuits controlled by said device and by said stick relay in its energized condition for effecting operations of said switch to its normal and reverse positions respectively, an indication device, means controlled by said stick relay in its deenergized condition for energizing said indication device, and other means controlled by said switch for energizing said indication device while said switch is in a position other than its normal and reverse extreme positions.

37 In combination, a stretch of railway track including a switch, a locking relay, means controlled by traffic conditions in said stretch for energizing said locking relay only if said traflic conditions are suitable for said switch to be moved between its extreme positions, a manually controllable device having a normal and a reverse position, normal and reverse switch control circuits controlled by said locking relay in its energized condition and by said manually controllable device in its normal and reverse positions for efiecting operations of said switch to its normal and reverse positions respectively, a normal signal relay, a reverse signal relay, a signal circuit controlled by said locking relay in its energized condition and by said switch and said manually controllable device in their normal positions for energizing said normal signal relay, a second signal circuit controlled by said locking relay in its energized condition and by said switch and said manually controllable device in their reverse positions for energizing said reverse signal relay, a third and a fourth signal circuit controlled independently of the position of said manually controllable device by said locking relay in its deenergized condition and by said switch in its normal and reverse positions for energizing said normal and reverse signal relays respectively, a first and a second signal for governing trafiic movements over said switch, means including said normal signal relay for controlling said first signal, and means including said reverse signal relay for controlling said second signal.

4. In combination, a stretch of railway track including a switch, a signal for governing traflic movements over said switch, a switch controller manually operable to a first or a second condition, a normally energized approach locking relay, means associated with said signal for deenergizing said approach locking relay when said signal is controlled to indicate proceed, means controlled by a train within a given distance to the rear of said signal for preventing reenergization of'said approach locking relay until the lapse of a given interval of time after said signal is again controlled to indicate stop, an auxiliary locking relay, a polarized switch indication relay having normal and reverse polar contacts and also neutral front contacts, a first and a second energizing circuit for said auxiliary locking relay controlled by a front contact of said approach locking relay and said first circuit also controlled by a normal contact of said indication relay and by said switch controller in its first condition and said second circuit also controlled by said switch controller in its second condition and by a reverse contact of said indication relay, normal and reverse pick-up circuits for said indication relay controlled by a front contact of said auxiliary locking relay and by normal and reverse contacts respectively of said switch, normal and reverse stick circuits for said indication relay which are the same as its pick-up circuits except controlled by one of its own front contacts instead of by a front contact of said auxiliary locking relay, means controlled by said switch controller in its first and second conditions for operating said switch to normal and reverse positions respectively, and means controlled in part by a front contact of said indication relay for clearing said signal.

5. In combination, a stretch of railway track including a switch, a signal for governing traffic movements over said switch, manually controllable means for operating said switch to its normal and reverse positions, a polarized switch indication relay having neutral front contacts as well as normal and reverse polar contacts, means manually controllable in part and also controlled in part by a front contact and a polar contact of said switch indication relay for clearing said signal, a normally closed locking contact, means associated with said signal for opening said locking contact when said signal is controlled to permit a traffic movement over said switch, control means for closing said locking contact only upon the lapse of a measured period of time after said signal is restored to the stop condition while a train is within a given distance to the rear of said signal, normal and reverse pick-up circuits for said switch indication relay controlled by said locking contact and by said switch in its normal and reverse positions respectively, and normal and reverse stick circuits for said switch indication relay controlled by one of its own front contacts and by said switch in the normal and reverse positions respectively.

6. In combination, a stretch of railway track including a switch, a signal for governing trafilc movements over said switch, manually controllable means for operating said switch to its normal and. reverse positions, a switch indication relay having neutral front contacts, means manually controllable in part and also controlled in part by a front contact of said switch indication relay for clearing said signal, a normally closed locking contact, means associated with said signal for opening said locking contact when said signal is controlled to permit a traffic movement over said switch, control means for closing said locking contact upon the lapse of a measured period of time after said signal has been controlled to indicate stop, means controlled by said locking contact and by said switch in its normal or its reverse position for energizing said switch indication relay, and means controlled by a front contact of said indication relay for retaining said indicating relay in the energized condition independently of said locking contact while said switch is in its normal or its reverse position.

7. In combination, a stretch of railway track including a switch, a signal for governing trafiic movements over said switch, a polarized switch indication relay having neutral front contacts as well as normal and reverse polar contacts, manually controllable means for clearing said signal, normal and reverse control circuits controlled by said switch in its normal and reverse positions for energizing said switch indication relay by current of normal or reverse polarity respectively only if said signal is controlled to indicate stop, manually operable switch apparatus, means controlled by said manually operable switch apparatus for operating said switch to normal and reverse positions only upon the lapse of a measured period of time after said signal is controlled to indicate stop while a train is within a given distance to the rear of said signal, and means controlled. by normal and reverse polar contacts of said switch indication re lay for operating said switch to its normal and reverse positions respectively before the lapse of said measured period, of time after said signal is controlled to indicate stop while a train is within a given distance to the rear of said signal.

8. In combination, a stretch of railway track including a switch, a signal for governing traffic movements over said switch, a polarized switch indication relay having neutral front contacts as well as normal and reverse polar contacts, manually controllable means for clearing said signal, an approach locking relay, means associated with said signal for energizing said approach locking relay upon the lapse of a measured period of time after said signal is controlled to indicate stop while a train is within a given distance to the rear of said signal, normal and reverse pick-up circuits for said switch indication relay controlled by said switch in its normal and reverse positions respectively as well as by a front contact of said approach locking relay, normal and reverse stick circuits for said switch indication relay controlled by one of its own front contacts and by said switch in its normal and reverse positions respectively, manually operable switch apparatus, means controlled by said manually operable switch apparatus and by a front contact of said approach locking relay for operating said switch to its normal and reverse positions, and means controlled by normal and reverse polar contacts of said switch indication relay for operating said switch to its normal and reverse positions respectively while said approach locking relay is deenergized.

9. In combination, a stretch of railway track including a switch, a signal for governing traffic movements over said switch, a switch indication relay, an approach locking relay, means associated with said signal ior energizing said approach locking relay when said signal is controlled to indicate stop, means controlled by a train within a given distance to the rear of said signal for delaying energization of said approach locking relay after said signal is controlled to indicate stop, means controlled by said'switch in its normal or its reverse position for energizing said switch indication relay only if said approach locking relay is energized, means controlled by a front contact of said switch indication relay for retaining said switch indication relay in its energized condition while Said switch is in its normal or its reverse position, manually controllable means for clearing said signal only if said switch indication relay is energized, manually controllable means for operating said switch to its normal and reverse positions only if said approach locking relay is energized, an indicator, means controlled by said approach locking relay in its deenergized condition for energizing said indicator, and means controlled by said switch indication relay for energizing said indicator while said switch indication relay is deenergized.

10. In combination, a stretch of railway track including a switch, a signal for governing traffic movements over said switch, manually controllable means, a traffic device arranged to be energized only if traflic conditions for said stretch are suitable for said switch to be operated, means controlled by said trafiic device and by said manually controllable means for operating said switch if said trafiic device is energized, a switch indication relay, means controlled by said switch in its normal or its reverse position and by said trafiic device for energizing said switch indication relay only if said traffic device is energized, manually controllable means for clearing said signal only if said switch indication relay is energized, an indicator, means controlled by said trafiic device for energizing said indicator if said traiiic device is deenergized, and means controlled by said indication relay for energizing said indicator if said indication relay is deenergized.

ll. In combination, a railway track switch, a

signal, manually controlled signal means operable to clear said signal to permit traffic movements to be made over said switch if said switch occupies a given extreme position, remotely controlled means operable to effect movements of said switch from each of its extreme positions to the other, manually operable means adjacent said switch for at times effecting movement of said switch to said given extreme position, and means con trolled by said switch and by said signal as well as by said remotely controlled means for prevent ing clearing of said signal by said manually controlled signal means even though said remotely controlled means is operated to the condition to correspond with the position of said switch when said switch has been moved to said given extreme position by said manually operable means adjacent said switch.

12. In combination, a railway track switch, a signal, manually controllable means for moving said switch from each of its extreme positions to the other, a switch indication relay, a pick-up circuit for energizing said switch indication relay only if said signal is controlled to indicate stop and only if said switch occupi s one of its ex treme positions or the other, a stick circuit for retaining said switch indication relay in the energized condition only if said switch occupies one of its extreme positions or the other, and

means controlled in part by said switch indication relay for clearing said signal to permit a trafiic movement over said switch and for retaining said signal in the clear condition whereby the control of the switch indication relay according to the control of said signal reduces the pinnping action of the signal which would occur if there were an intermittent shunt or open circuit in the control circuits for said switch indication relay.

13. In combination, a railway track switch, a signal for governing tramc movements over said switch, a signal control device manually operable to clear said signal if said switch is in its normal position, a switch control device manually oper- .able to a first or a second condition for setting said switch into operation toward its normal or its reverse position respectively, a second switch control device manually operable to a reverse position to remove said first switch control device from control of said switch to permit said switch to be manually actuated, and means controlled by said switch and by said signal for preventing storage of control of said switch by said first switch control device if while said signal is clear said second switch control device is operated to remove said first switch control device from control of said switch and if said switch is then manually actuated and if then said first switch control device is put into its second condition and said second switch control device is afterwards returned to its normal position.

14. In combination, a stretch of railway track including a switch, a stick locking relay, a manually controllable device having a normal and a reverse position, a pick-up circuit for said stick relay controlled by said device and by said switch and closed if said device is in its reverse position while said switch is in its reverse position, a second pick-up circuit for said stick relay controlled by said device and by said switch and closed if said device is in a position other than its reverse position while said switch is in its normal position, a stick circuit for said stick relay controlled by trafiic conditions in said stretch, normal and reverse switch control circuits controlled by said device and by said stick relay in its energized con dition for effecting operations of said switch to its normal and reverse positions respectively, an indication device, and means controlled by said stick relay in its deenergized condition for energizing said indication device.

15. In combination, a railway track switch, a signal for governing trafiic movements over said switch, manually controllable means for moving said switch from each of its extreme positions to the other, a switch indication relay, a pick-up circuit for energizing said switch indication relay after said signal has been controlled to indicate stop a measured period of time and only if said switch occupies one of its extreme positions or the other, a stick circuit for retaining said switch indication relay in the energized condition only as long as said switch remains in one of its extreme positions or the other, and means controlled in part by said switch indication relay for clearing said signal to permit a trafiic movement over said switch for reducing the pumping action of the signal which would occur in the event of an intermittent shunt or open circuit in the control circuits for said switch indication relay.

16. In combination, a railway track switch, a signal for governing trafiic movements over said switch, manually controllable means for moving said switch from each of its extreme positions to the other, a switch indication relay, a pick-up circuit controlled in part by said signal for energizing said switch indication relay after said sig nal has indicated stop a measured period of time, a stick circuit for retaining said switch indication relay in the energized condition as long as said switch remains in one of its extreme positions or the other, a manually controllable circuit for clearing said signal, and a front contact of said switch indication relay included in said manually controllable circuit for reducing the pumping action of the signal which would occur in the event of an intermittent shunt or open circuit in the control circuits for said switch indication relay.

EARL M. ALLEN. HENRY S. YOUNG.

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