US1982181A - Railway traffic controlling apparatus - Google Patents

Description

Nov. 27, 1934. P.- P. STOKER RAILWAY TRAFFIC CONTROLLING APPARATUS original Filed Feb. s, 1928 Patented Nov. 27, 1934 UNITED STATES PATENT OFFICE RAILWAY TRAFFIC CON TROLLING APPARATUS Application February 3, 1928, Serial No. 251,576 Renewed April 30, 1930 v32 Claims.

My invention relates to railway trafc controlling apparatus, and particularly to apparatus of the type lintended for safely controlling railway traic governing devices, such as railway switches and signals from a remote point.

I will describe one form of railway traic controlling apparatus embodying my invention, and will then point out the novel features thereof in claims. i

The accompanying drawing is a diagrammatic View showing one form of railway traino controlling apparatus embodying my'invention.

Referring to this drawing, the reference characters 1 and 1a designate the track rails of a stretch of railway track connected with a siding 4,

by a switch 3 of the usual and well known form.

The rails 1 and 1EL of the main track are divided,

by means of insulated joints 2, to form a plurality of successive track sections A B, B-C, C D, D E, and E F. The rails of siding 4 are also divided by means of insulated joints 2 to form a track sectionG-H, the rails of the siding to the left of point G being connected with the rails of section C D in accordance with the usual practice. Each track section is provided with a track battery 10 connected across the rails adjacent one end of the section, and with a track relay connected across the rails adjacent the other end of the section and designated by the reference character R with a suitable distinguishing exfponent. Each track relay R is normally energized, but is arranged to 4open when a train enters the corresponding section.

Associated with the switch 3 is a circuit controller designated in general by the reference 'character J. When the switch 3 is in its normal position, in which it is illustrated in the drawing, contacts 5 5a and 6 6a are closed. Whengthe switch occupies its reverse position, contacts 5 5b 49 and 6 6b are closed. The circuit controller J also comprises contacts 8 8a and 9 9a which are closed at all times except when the 'switch occupies its reverse position. Contacts 8 8b and 13 95 are closed at all times except when the switch occupies its normal position. The reference character 7 designates a pole-changer by means of which a polar indication relay K is connected with the terminals X and Y of a suit- 50 able source of energy not shown in the drawing. vlWith this arrangement, when switch 3 occupies its normal position, the relay K is energized in ,one direction so that the polar contact 50 is swung to the left. When switch 3 is reversed, I however, the pole-changer 7 reverses the polarity of the current supplied to relay K and causes polar armature 50 to swing to the right.

Westbound trahie, that is, tranc moving from right to left, over the portion of track shown in the drawing iscontrolled by two signals S?4 and S4, and traic in Vthe opposite direction is controlled by two similar signals S1 and S3, which in the form here shown are mounted on the same mast. The signals S are illustrated in the drawing as semaphore signals, but this particular form is not essential. The switch 3 and the signais associated 'therewith are arranged to be controlled manually from a remote point. In the form of apparatus here illustrated, this is accomplished by means of a plurality of selectors, each designated by the reference character W with a distinguishing exponent and each comprising an operating winding 11 and a contact controlled thereby. The operating windings 11 of all the selectors are connected in parallel across a pair of line wires 97 and 97a. The selectors W are selectively responsive to control codes which may be impressed upon the line Wires 97 and 97a by any suitable means. It is frequently desirable to control the selectors by means of a code transmitter indicated diagrammatically at T and located at some central control point such for example as a train despatchers oiiice. Each of the selectors'Wl, W2, W3 and W4 comprises a normally open contact 12` which is arranged to be closed for a brief interval of time when the corresponding selector receives its proper control code. The selector W5 comprises a normally closed contact 12a which is arranged to be opened for a brief interval of time when selector W5 receives its proper control code.

The reference characters QE and QW designate two signal relays which, or traffic direction stick relays, are controlled by the selectors W3, W4 and W5. Thegrelay QE is provided with a pick-up circuit which may be traced from terminal X of a suitable source of energy not shown in the draw- Ving through Contact 12 of selector W3, wires 13 and 14 and winding of relay QE` to the terminal Y of the same source. Relay QE is also provided with a stick circuit from terminal X, over contact 12a of selector W5, wires 15 and 16, back contact 17 of relay QW, wire 18, front contact 19 of relay QE, wires 20 and 14, and winding of relay QE, to terminal Y. It is plain, therefore, that relay QE may be energized by operating selector W3 and that after the relay has once picked up, it will be maintained in its energized condition until relay QW is closed to open back contact 17, or until selector W5 is operated to open contact 12'.

R3 andpush button Z.

When relay QE is energized, signal S1 or signal S3 is cleared depending upon the position of switch 3. If the switch occupies its normal position,current flows from terminal X over Wire 56, front contact 57 of track relay R3, Wires 58, 59 and 60, front contact 61 of relay QE, wire 62, contact 6-62 of circuit controller J, wire 63, and operating mechanism of signal S1 to terminal Y. If switch 3 occupies its reverse position, the energization of relay QE completes an operating circuit for signal S3 which may be traced from terminal X, over wire 56, front contact 57 of relay R3, wires 58, 59 and 60,front contact 61 of relay QE, Wire 62, Contact 6--6b of circuit controller J, wire 64, and operating mechanism of signal S3 to terminal Y. It follows therefore that if section C-D is unoccupied and if relay QE .isener-f gized, signal S1 or signal S3 will be cleared accordf ing as switch 3 occupies its normal or its reverse position.

Insin'iilar manner, the signals S2 and S3 governing westbound traffic are controlled by relay QW and thisrelay is provided with a pick-up circuit controlled by selector ,W4 and a stick circuit `controlled by relayl QE and selector W5. The circuits for relay QW are similar to the circuits al-` ready traced for relay QE and-will be readily understood from the drawing Without further explanation. l s

The switch 3 is controlled in part by two approach locking relays L1 and L2. Referring first tcrelay L1, this relay is provided with a pick-up circuit from terminal X, over wire 21, back contact 22 of track relay R3, wires 23, 24 and 25, and

winding of relay L1 to terminal Y. The relay L1 may also be energized by actuating a manually operable push button Z which is preferably located in the trackway adjacent the switch 3. When this push button is operated, current flows from Iterminal X, through wire 26, contact 98 of push button Z, wires 27, 28, 24 and 25, winding of relay L1 to terminal Y. Relay L1 is also provided with a stick circuit from terminal X, over wire' 29, back contact 30 of relay QE, wire 31, front contact 32 of relay L1, wires 33`and 25 and winding of relay L1 to terminal Y. Still another stick circuit is provided for relay L1 which may be traced from terminal X, over wire 34, front Contact 35 of relay R1, wire 36, front contact 37 of relay R2, wire 38, front Contact 30 of relay QE,

wire 31, front Contact 32 of relay L1, wires 33 and 25, and winding of relay L1 to terminal Y. It-

follows, therefore, that if relay L1 is once energized, as by the de-energization of relay R3, or by operation of push button Z, the relay will subsequently be maintained in its energized condition as long as relay QE is cie-energized. 1f relay fQE becomes energized, however, the locking relay L1 is held in its energized condition only if track relays Rl'and R2 of approach section 1 -C for trafc moving from left to right are both energized.

The relay L2 is provided with two pick-up circuits similar to the pick-up circuits already traced for relay L1 and controlled respectively `by relay It follows thatthe locking relay L2 is picked up by de-energization of relay 112.3 or'by the actuation of the push button Z. Relay rL2 having Yonce been energized, is held closed as long as .signal relay` QW is `de-energized, by'virtue of a stick circuitwhich passes from terminalX, overv wire 39, back contact 40 of relay QW, wire 41, front contact 42 of relay L2, wiresl 43 and 44and winding of vrelay L2 to terminal Y.

If relay QW is energized, however, the stick circuit `for relay yL2 is Vcontrolledrby traffic conditions in of relay R5, wire 49, normal contact 50 of relay K, wire 99frontcontact 51 of relay K, wire 52, front Contact 40 of relay QW, wire 41, front contact 42 of relay L2, wires 43 and 44, and winding of relay L2 to terminal Y. If, however, switch 3 is reversed, and if relay QW is energized, the stick circuit for relay L2 passes from terminal X, through wire v53, .front contact 54 ofl relay R4, wire 55, kreverse contact of relay K, wire 99, front contact 51 of relay K, wire 52, front contact 40 of relay QW, wire 41, front contact 42 of relay L2, wires 43 and 44, and winding -of yrelay L2 toterminal Y.

The switch` 3 is actuated Iby a motor which in the .form here shown comprises :an'armature 91 and a field 92 and which-is in turn controlled by two lswitch relays, or route stick-relays, PR and PN. The switch relays PR and PN are controlled by the locking relays L1 and L2 and also by selectors W1 and W2. As shown in the drawing the switch 3 occupies its normal .position and the switch relays PR,V and PN are both de-energized so that the motor M is cie-energized, but relays Ll .and L2 are both energized. If, now, :selector W1 is operated to close contact 12, current flows from terminal X, over Wire 56, front contact '57 of relay R3, wires-58, 70 and 7l, contact `12 of selectorW1, Wires '72 and 73, vwinding of` relay. PE, wires 74 and 75, front contact '76 of relay L1, Wire 77, and front contact 78 of yrelay vL2 to terminal Y. ,Relay PR ltherefore becomes PE, Wires 87 and '73, vwinding of relay PE, wires 74 and 75, front contact 76 of relay L1, wire 77 and front contact '78 of relay L2 to terminal Y. It should be noted that the stick circuit for relay PR includesback contacts on the signal relaysQE and QW so that the switch relay PR` can vnot be held closed unless the signal relays are both deenergized to `insure that the associated signals all indicatev stop. Furthermore, both the-pick-up andthe stick circuits ofthe switch relay PR in- 'clude `front contacts of the track relay R3 and..

the locking relays L1 and L2.

When relay PR isenergized, current flows from termina'lX, over wire 88, front contact 89 of relay PE,wire 90, armature 91 of v,motor M, wire 93,

back contact 94 of relay PN, wire 95, contact 9-9a of circuit controller J, wire 96, and eld'92 of motor M'to terminal Y. The motor M is theretains its full reverse position, contact 8--8b opens to break the stick circuit for relay PE, :to de-energizemotor M. The motor circuit is also opened at contact *9-912 `which Ais open when the switch occupies its reverse position.

`Thecontrol Aof relay'PN'by selector W2 is similar to' that already described in connection with the control of relay PR by selector W1, and it willI therefore be plain that if selector W2 is operated, relay PN will be picked up, and stuck up over contact 8 8a of circuit controller J. When relay PN is energized, current from terminal X flows over wires 88 and 882 front contact 94 of relay PN, wire 93, armature 91 of motor M, wire 90, back contact 89 of relay PR, wire 100, contact 9--9a of circuit controller J, wire 96, and eld 92 of motor M, to terminal Y. When this circuit is closed, the motor M is operated to move switch 3 to its normal position. When the switch has attained its full normal position, the opening of Contact 9 9@ interrupts the circuit for motor M. It should also be observed that the stick circuit for relay PN includes contact 8-82, so that when the switch is restored to its normal position, the relay PN becomes de-energized. I

It will be observed that the circuits for the switch relays PR and PN each include front contacts on the locking relays L1 and L2. It is therefore impossible to operate the switch 3, except when the locking relays are both energized. Under normal conditions, that is, when the signal relays QE and QW are both de-energized so that all signals indicate stop, the locking relays L1 and L2 are stuck up over back contacts of the signal relays. Furthermore, if either of the signal relays is energized to clear the corresponding signal, the relays L will continue in their energized condition provided the track relays are all energized. The circuits are so arranged, however, that if a train enters the approach section for the switch when the signal has beencleared for governing traic in the direction in which such train is travelling, one of the locking relays L will be de-energized, thereby preventing operation of the switch 3. For example, I will assume that the switch occupies its normal position and that relay QE has been energized to clear signal S1. Under these conditions, the stick circuit for relay L1 passes over front contacts of the relays R1 and R2. If, now, a train moving from left to right, approaches the switch 3 and enters either of sections A-B or B-C, the de-energization of the corresponding track relay will interrupt the stick circuit for relay L1 and will cause this relay to become de-energized. Of course, relay L2 remains in its energized condition but the opening of front contact '76 of relay L1 opens both the pick-up and stick circuits for both relays PR and PN so that it is impossible to operate the switch 3. It should be noted that if the train continues to move toward the right and enters the switch section C-D, the deenergization of relay R3 completes a pick-up circuit for relay L1. If, now, relays R1 and R2 both become energized, the stick circuit for relay Ll is re-established and the switch may be operated, by picking up one of the switch relays P, as soon as the train has left section C-D to allow relay R3 to become energized. In similar manner, if switch 3 occupies its normal position, and signal relay QW is energized, the relay L2 is stuck up over front contacts of relays R5 and R6. If a westbound train approaches the switch under these conditions, the relay L2 will become de-energized as soon as the train passes point F and it will therefore be impossible to operate the switch. 3 until relay L2 has again been energized as by the entrance of the train into section C-D, and relay R3 has subsequently been re-energized. It should be observed, however, that if relay QW is energized with switch 3 reversed to clear signal S4, the stick circuit for relay L2 is controlled by relay R4, so that under these conditions the apparatus is locked up by the approach of a westbound trainvtoward the switch along the siding 4, as soon as such train passes point I-I.

Under some conditions of operation it is desirable to release the approach locking without requiring the train to actually enter the section which contains the switch. It is for this purpose that the push button Z is provided, and it should be noted that when a train approaches a cleared.`

signal, thereby de-energizing one of the locking relays L1 or L2, the locking relay may again be picked up by the operation of push button Z. If the signal relays Q may have been de-energized in the meantime, the locking relays will remain in the energized condition after operation of push button Z, so that the switch may then be operated from the despatchers oii'ice. It should be observed that signals may be cleared and restored to the stop position without causing deenergization of the locking relays L provided no train accepts the clear signal by approaching when the signal is at clear position. For'example, with switch 3 normal, relay QE may be energized to clear signal S1 and the selector W5 may then be operated to de-energize relay QE and restore the signal to stop without affecting relay L1, alr though if relay QE is energized, relay L1 would become de-energized if a train entered section A-B. In order to bridge the interval of time required for operation of relay QE, relay L1 may be made slightly slow acting, or the front and back points of contact 30 of relay QE may be made to overlap. In similar manner the parts are so arranged that relay L2 remains closed during an operation of relay QW.

Although I have -herein shown and described only one form of railway traffic controlling 'apparatus embodying my invention, it is understood that various changes and modications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what' I claim is:

1. In combination with a railway switch, a con-A tact, manually controlled means for at times operating said switch provided said Contact is closed, a signal governing traffic over said switch, a signal relay controlling said signal, means effective when said signal relay occupies one position to hold said contact closed independently of l tact of said signal relay, a second stick circuit for said locking relay including a front contact of said signal relay and a contact of said track relay, and-manually controlled means effective when said lockingrelay is energized to operate said switch.y

3. In combination with a railway switch, a manually controlled signal relay, a signal 'controlled by said signal relay and governing trahie over said switch, a push button located in the trackway, a track relay responsive to traic conditions adjacent saidl switch, a locking relay, `a pick-up circuit for the locking relay controlled by said push button, a first stick circuit for said locking relay including a back Contact of said Signal relay, a second stick circuit for said locking relay including a front contact of said signal relay and controlled by said track relay, a manually operableselector, a switch relay controlled by said selector and by said locking relay, and a motor controlled by said switch relay for operating said Switch 4. In combination with a railway switch, a' manually controlled signal relay, a signal controlled by said signal relay and governing traillc over said switch, a push button located in the trackway, 'an indication relay controlled in accordance with the position of said switch, a lock'- ing relay, a pick-up circuit for the locking relay controlled by said push button, a rst stick circuit for said locking relay including a back contact of said signal relay, a second stick Circuit for said locking relay including a front contact of said signal relay and a contact of said indication relay and responsive to traffic conditions adjacent the switch, a manually operable selector, a switch relay controlled by said selector and by said locking relay, and a motor controlled by said switch relay for operating said switch.

5. In combination with a stretch of main railway track, a siding, a railway switch for at times connecting said siding with said stretch, a manually controlled signal relay, a signal controlled by said signal relay for governing traffic over said switch, a polar indication relay responsive to the position of said switch, ka locking relay provided with a pick-up circuit, a first stick circuit for said locking relay including a back contact of said signal relay, a second stick circuit for said locking relay including a iront contact of said signal relay land responsive to traffic conditions in said siding or in `said main track depending upon the condition of said indication relay, and means controlled by said locking relay for operating said switch.

6. In` combination, a section of railway track, a track relay for said section, a manually controlled signal relay, a locking relay, a pick-up circuit for said locking relay including a back contact of said track relay, manually operable means for energizing said. locking relay, a first stick circuit for said locking relay including a back contact of said signal relay, a second stick circuit for said locking relay including a front contact of said signal relay and responsive to traine conditions adjacent said section, and a railway switch iny saidsection controlled by said locking relay.

'7. In combination, ai section of railway track, a railway switch in said section, manually controlled mechanism for operating said switch, a railway signal governing traiiic through said section, manually controlled means for controlling said signal, a manually operable push button, means vset into operation when a train approaches said section while said signal is clear for rendering said mechanism ineffective to operate said switch until said train has passed through said section or until said push button is operated.

8. In combination, a section of railway track containing. a railway track switch, a signal 'for governing traiiic movements over said switch, a control circuit for said signal, a track relay for said section, a locking relay, a pick-up circuit for said lockingV relay controlled by said track relay, a stick circuit for said locking relaycoritrolled by said signal control circuit, a switch relay con.-

trolled by saidy locking relay and by saidY track relay, and means controlled by said switch relay for operating said switch.

9. In combination, a section of railway track containing a railway track switch, a signal for governing trailicmo-vements over said switch, a control circuit for said signal, a track relay for said section, a locking relay controlled by said track relay and by said signal control circuit, a third relay controlled by said locking relay and by said track relay, and means controlled by said thirdv relay for controlling said switch.

10. In combination with a railway vtrack switch, an indication relay responsive to the condition of said switch, a signal for governing trai'lic over said switch, a control circuit for said signal, a stick relay, a manually controlled pick-up circuit for said stick relay, a stick circuit for said stick relay controlled by said indication relay and by said signal control circuit, and means controlled by said stick relay for operating said switch.r

11. In combination with a railway track switch, an indication relay responsive to the condition of said switch, a signal for'governing traiiic over said switch, a control circuit for said signal, a stick relay, a manually controlled pick-up circuit for said stick relay, a stick circuit for said stick relay controlled by said indication relay and by-said signal control circuit, operating mechanism for said switch, and mea-ns controlled by said stick relay for at times disabling said mechanism.

l2. In combination with a railway track switch, an indication relay responsive to the condition of said switch, a signal for governing trailic over said switch, a control circuit for said signal, a 1u' stick relay, a manually controlled pick-up circuit gized only if said signal control circuit is ener- 5 5 gized, a stick relay, a pick-up circuit for saidv stick relay controlledby said track relay, a stick circuit for said stick relay controlled by said locking relay,l and means controlled by said stick relay for controlling said switch.

ics-

14. In combination, a section of railway track lcontaining a switch, a track circuit for said section including a track relay, a signal for governing traiiic movements over said switch, a control relay for said signal, a stick relay, a pick-up cirje cuit for said stick relay controlled by a back con- .is energizedonly if said signal control circuit is energized for controlling'said energized, and means controlled by` said stick relay for operating said switch.

16. In combination, a main `section and an approach section or" railway track, a switch in said main section, a signal for governing traiiic movements over said switch, a .control relay for controlling said signal, a stick relay, a. pick-up circuit for saidstick relay controlled by traino conditions in said main section, a stick circuit for said stick relay controlled by trairlcconditions in said approach section when said control relay is energized and controlled independently of traic conditions when said control relay is deenergized, and means controlledby said stick relay for operating said switch. l

17. In combination, a main and an approach section of railway track, a switch in said main section, a signal for governing traflic movements over said switch, a control circuit for said signal, two track relays one for each said section,y a manually operable circuit controller, a stick relay having pick-np and stick circuits one of which is controlled by one of said track relays and is energized if and only ii said signal is controlled to display a proceed indication and the others of which are controlled by said circuit controller and by the other of said track relays, and means controlled by said stick relay for operating said switch.

18. In combination, a section of railway track including a switch, a track circuit for said section including a track relay, a signal for governing traiiic movements over said switch, a signal control relay, a circuit for clearing said signal including iront contacts of the signal signal, an approach track section, a second approach track section, a stick relay, a manually controlled pick-up circuit for said stick relay, a stick circuit for said stick relay controlled by said signal control circuit and also controlled .by trailic conditions in said i'lrst approach section if and only if said indication relay responds to a given condition of said switch, a second stick circuit for said stick relay controlled by said signal control circuit and also controlled by trafiic conditions in said second approach section if and only ii said indication relay responds to a second condition of said switch, and means controlled by said stick relay for operating said switch.. v

20. In combination, a railway track switch, an

indication relay responsive to the condition ofv said switch, an approach track section, a second approach track section, a stick relay, a manually controlled pick-up circuit for said stick relay, a stick circuit for said stick relay controlled by traffic conditions in said first approach section if and only if said indication relay responds to a given condition of said switch, a second stick circuit for said stick relay controlled by traffic vconditions in said second approach section if and only if said indication relay responds to a second condition of said switch, and means controlled by said stick relay for operating said switch.

21. A railway system having a track switch and a plurality of signals for governing traffic movements over said switch, apair of relays at said switch for controlling said switch, manually operable control means at a remote point for transmitting code signals to selectively operate one or `the other of said relays to control said switch, and means for preventing the operation of either of said relays if a train approaches within a given distance of one of said signals while-the signal is displaying a proceed indication.

22. In combination, a railway track switch hav` ing a normal and a reverse position, a Asignal for governing tra-inc movements over said switch, a rst and a second switch relay, a circuit for energizing said first switch relay for causing an operation of said switch to its `normal position, a second circuit for energizing said second switch relay for causing an operation of said switch to its reverse position, an approach locking relay which becomes deenergized if a train approaches said switch while said signal is controlled to display any other than a stop indication, and means controlled by said approach locking relay for deenergizing said switch relays if said approach locking relay is deenergized. 1

23. A system of railway trafc route signaling comprising a switch and a plurality of signals for governing traffic movements over'said switch, a pair of route stick relays, a pair of traffic direction stick relays, means for energizing one or the other of said route stick relays for causing an operation of said switch to its normal or its reverse position respectively, means for energizing one or the other of said traiiic direction stick relays for clearing a signal for a given direction of traiiic movement or for the opposite direction respectively, approach locking means for preventing energization of said route stick relays but permitting energization of said traic direction stick relays, and means for rendering saidY approach locking means eiective to deenergize said routefstick relays when a train approaching one of said signals arrives at a given point if and only if the signal is controlled to display a proceed indication. Y

24. In combination, a section of railway track containing 'a track switch over which trafiic may move in either of two directions, selecting means manually controllable fromia point remote from the switch for operating the switch and for governing the direction of traffic movement over the switch, an approach locking relay, means for deenergizing said relay when a given direction of traffic is established by said selecting means provided a train vapproaching in said direction is within a predetermined distance of the switch, but for maintaining said relay energized at other times independently of traiiic conditions, r and lli] means eilective when said relay is` deenergized for preventing operation of said switch by vsaid selecting means.

25. In combination, a section of railway track containing a track switch over which traffic may move in either of two directions, manually controllable selecting means for governing the direction of traino movement over the switch, an approach Ysection adjacent said switch section,

leid.

an approach locking relay, means for controlling p.

said relay in accordance with the condition of said approach section when and only when said selecting means is controlled to permit a traffic movement in the direction from said approach section to said switch section, and means conlio.

lain."

` trolled by lsaid approach locking relay for concontaining ,a track switchover which Itrai'lic may csi move in either of two directions, manually controllable selecting means for operating said switch and `for governing the direction of trailic movements over the switch, two approach locking relays one for each direction; means for deenergizing one of said relays when one direction of traic is established, and for deenergizing the other relay when the other direction of traffic is established by said selecting means provided a train moving in the direction established is within a predetermined distance of said switch; and means effective when either of said relays is deenergized for preventing operation of said switch by said selecting means. Y

v2'1. In combination, a stretch of railwaytrack over which trailic may move in either direction comprising a section containing 'a track switch and two approach sections :one at each end of said switch section, manually controllable selecting means for governing the direction of traiiicmovement over the switch, an approach locking relay for each approach section, means for controlling each said relay in accordance vwith the condition of the corresponding approach section when and only when the selecting means `is controlled to permit a traflic movement in the direction from such section to the switch section, and means.

controlled by said approach locking relaysfor controlling said switch.

28. In combination, a stretch of railway track over which traffic may move in either direction ycomprising a section containing a track switch and two approach sections, including one at each end of said switch section, manually controllable selecting rmeans for governing vthe direction of trafc movement over the switch, an approach locking relay for each approach section, means for deenergizing each said relay when the corresponding approach section is occupied and the selecting means is controlled to permit a traffic movement in the direction from'such section to the switch section, means for energizing each said relay when the switch section becomes occupied, and means for operating the switch effective only when kthe switch section is unoccupied and both saidrelays are energized.

' 29. In combination, a section of railway track containing a track switch, a pair of opposing signals for governing traic over the switch, a track circuit for said switch section having a track relay, manually controllable selecting means effective when said track relayvis energized to clear one signal or the` other to permit the movement of traffic over the switch in one direction or the other, two approach locking relays one for each direction, a pickup circuit for each approach locking relay including a back contact of said track relay, a-stick circuit for each approach locking said approach locking relays and byv said track relay for controlling said switch.

30. In combination, a'stretch of railway track comprising a section containing a track. switch and two approach .sections one at each end of said switch section, two Signals one at each end of said switch ,section for `governing traic approaching said switch through the adjacent approach section, a stick relay for each signal, manually con.- trollable signal selecting means for selectively energizing one stick relay or kthe other, or `for releasing `such relay when energized, manually controllable switch control means for operating the switch eiective only whenboth said stick relays are deenergized, and approach locking means arranged to prevent operation of the switch con'-V trol means provided one of said stick relays becomes deenergized when the approach section adjacent .the signal controlled byy such relay is' Van approach track section, a second approach track section, `a stick relay, means for picking up said stick relay, al first stick `circuitior ksaid stick relay controlled -by `said signal control relay and by traffic conditions in said rst approach section if and only if said indication relay is energized in said one direction, a second stick circuit for said stick relay controlled by said signal control relay and -by traic conditions in said second approach section if and only if said indication relay is energized in said other direction, vand means controlled by said stick relay for operating 4said switch,

32. In combinationwith a switch section of railway trackcontaining a track switch adapted to beoperated to one position for trailic approaching said switch from an adjacent main track section and tofanother position for traffic approaching said switch from an adjacentsiding, an approach Y locking stick relay, a rpickup circuit for said relay closed only when said switch section is occupied, stick circuits for said ,relay controlled by a train approaching said switch in said main track section or in ,said siding in accordance with the position of said switch, and means for-preventing the operation of said switchV except whensaid stick relay is energized and said switch section is unoccupied.

PAUL P. STOKER.`

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