US2742563A - Time locking control apparatus for railways - Google Patents

Description

April 17, 1956 A. HOOGERHYDE TIME LOCKING CONTROL APPARATUS FOR RAILWAYS Filed Nov. 50, 1951 2 Sheets-Sheet l April 17, 1956 HQOGERHYDE TIME LOCKING CONTROL APPARATUS FOR RAILWAYS Filed Nov. 30, 1951 2 Sheets-Sheet 2 g Q m E W w A ER W n W w W. A a A m w S m w m m m w m R a 0% m K mm M Q UT m wwww w W w m "HT m u g m M wfi m m EM 11,----l--i:l W SB 1? i LP RN 1F 4 w NI for railways.

2,742,563 I tented Apr. 17, 1956 TIME LOCKING CONTROL APPARATUS FOR RAILWAYS Arthur Hoogerhyde, Verona, Pa.', assignor to Westing house Air Brake Company,Wilmerding, Pa., a corporation'of Pennsylvania Application November 30, 1951, Serial No. 259,045 13 Claims. (Cl. 246-160) My invention relates to time looking control apparatus More specifically, my invention relates to a releasing arrangementfor time locking controlapparatusfor railways such, for example, as approach looking apparatus for railway traffic governing devices which may be track switches in an interlocking'plant.

This application is a continuation in-part of my earlier A l a home signal is controlled to display a stop indication,

if a train has arrived adjacent the signal before the signal is controlled to display the stop indication. I

I shall describe two forms of apparatus embodying my invention,-and shall then point out the novel features thereof in claims. 1

l'n the accompanying drawings, Fig. 1 is a diagraminatic view'showing one form of apparatus embodying my invention, in which the stretch of track between a V home'signal Zand its approach signal 2D is divided into application for Letters Patent of the United States, Serial No. 239,446, now abandoned,'filed July 31, 1951, for Time Locking Control Apparatus for Railways. Fig. 1 of the present application corresponds to Fig.1 ofithe earlier application, and Fig. 2 of the present application I is a modification of Fig. 2 of the earlier application.

When setting the operating time of releasesfor approach locking, railroads generally make use of a standard formula given in Part 128 of The Association of American Railroads Signal Section Instructions. As determined by that formula, the length of the releasing time depends largely on the distance between a home signal and an approach signal for the home signal which controls traflic movements over a switch or other't'rafiic governing device to which the approach locking is applied,

so that, ifthe distance is long between the home signal v the releasing time Types of traffic movements'which may result in hnnecessarily long delays to trains are as follows: (l)i If a train approaches a home signal which has been controlled to display a proceed indication for a through traffic movement on a main track, but the engineman of the train wishes to make a movement onto an auxiliary track to leave a bad order car such, for example, as a car with a hot box. (2) If a train moves off of an interlocking track layout or siding area, and a leverman controls a home signal to display a proceed indication for the train to reenter the interlocking trackklayout or siding area by a route other than that which is desired by the engineman on the train.

With either of these two types of traffic movements, the home signal will be controlled to display a stopindication after having first been controlled to display 'a proceed indication; operation of the time releasing means for the approach locking will be thereby initiated; upon expiration of the release time period, the switches for,

the desired route can be moved to the positions in-which they are included in that route; and the home signal can then be controlled to display a proceed indication for the desired route. With time releasing-arrangements :previously used, a long release period would be imposed in the event of either of the two types of trafiic move mentsreferred to, even if the train had stopped before two approach sections designated by the reference characters AT and ET; in which two time element devices or relays which may be of the well-known thermal type, designated by the reference characters TER and ATER, are provided; in which two approach locking relays designated by the reference characters 2LSR an d A2LSR are provided; and in which the approach control of relay ZLSR is inresponse to occupancy of an approach section CT inthe'rear of signal 2]) and in response to-occupancy of section BT, whereas the approach control of relay AZLSR is in response to occupancy of section AT only.

Fig. 2 is a diagrammatic view showing a modification of the apparatus of Fig. 1, also embodying my invention, in which only one approach locking relay ZLSR is provided; in which an approach relay, designated by the reference character 2AR,'is of the polarized type, and is controlled to 'be energized by current of reverse polarity when any one of the approach sect-ions AT, BT and CT is occupied by a train; and in which the approach control of relay ZLSR is effected by-relay 2AR in response to occupancy of any one of the'three'section s'AT, BT and Similar reference characters refer to similar parts in each of the views} w In'each of the Figures 1 and 2 of the drawings, a stretch of railway track is shown including a track switch, designatedby the reference character 3.- In order to simpljfy 'the drawings, each track, comprising two parallel series of track rails, is represented by a single line.

The stretch of trackis divided by insulated joints 1 to form a detector track section, designated by the reference character 3T, in which switch 3 is located, and a first and asecond and alsoI-a third approach section designated by the reference characters CT, BT and AT, respectively. Each of the track sections is provided with a track circuit includinga suitable sourceof current such, for example, as a batteryf4, connected across the rails adjacent'one' end of the section, and a track relay, designated bythe reference character R preceded by the reference character for the corresponding section, connected across the rails adjacent the oppositeend of the section.

A home signal 2 isshown for governing traflic movements over section 3T, past switch 3, in a given direction from right to left, as shown in the drawings, which I shall assume is the westbound direction. An approach signal, designatedby the reference character 2D, is shown,

in the rear of section 'BT and in advance of section CT,

for governing trafiicmovements over sections BT and AT 3 in the westbound direction, toward signal 2. Signals 2 and 2D may be of any suitable design such, for example, as the well-known scarchlight type.

Switch 3 is operable between a normal extreme position, in which it is shown in the drawings, anda reverse extreme position, by suitable mechanism, designated by the reference character 3M. Energization of mechanism 3M for moving switch 3 between its two extreme positions is controlled by a switch locking relay, designated by the reference character 3LR, and by a manually operable switch control device such, for example, as a lever, designated by the reference character 3V.

Signal 2 is provided with a suitable mechanism, designated by the reference character 2G, which ,is operable from a normal or deenergized position to an approach proceed position or to a clear proceed position. While mechanism 2G is deenergized, signal 2 displays a stop indication, and when mechanism 26 is moved to the approach or clear proceed position, signal 2 displays an approach proceed indication or a clear proceedindication,

respectively. Energization of mechanism 2G is controlled by a manually operable signal control device s1 1ch,.for example, as a lever, designated by the reference character 2V. Selection between the approach and the clear proceed position is effected by suitable means not part of my invention, and therefore not shown in the drawings.

Each of the levers 2V and 3V has a normal position, designated by the reference character 11, in which it is shown in the drawings, and a control position, designated by the reference character 1'. Lever 2V has also a second control position designated by the reference character f. Contacts operated by levers 2V and 3V are represented on the drawings by circles, in which are placed reference characters to show the positions of the respective levers in which the contacts are closed. Contact of lever 2V, for example, shown in the lower left-hand corner of each of the drawings, is closed only while lever 3V is in the n position, as indicated by the reference character n in the circle for this contact. Contact 34 of lever 2V, in Fig, 2, as another example, is closed only while lever 2V is in the n or the r position or at any point between thesepositions, as indicated by the reference character nr in the circle for this contact.

Signal contacts, designated by the reference characters g and y, are operated in conjunction with signal mechr anism 2G, and are normally closed, while mechanism 2G is in the deenergized position, but are arranged so that contact g will be opened when mechanism 2G is moved to the clear proceed position, and contact y will be opened when mechanism 26 is moved to the approach proceed position. 1

A signal indication relay, designated bythe reference character 2RP, is controlled by contacts g and y, so that it is normally energized while mechanism 2G is inthe deenergized or stop position, but becomes deenergized when mechanism 2G is moved to either of its proceed positions.

A suitable source of current may, for example, be a battery, shown in the drawings and designated by the reference character Q, having terminals designated by the reference characters B and N.

Referring to Fig. 1 of the drawings, an approach relay, designated by the reference character 2AR, is here controlled by front contacts of relays BTR and CTR.

A first and a second approach locking relay, designated by the reference characters 2LSR and A2LSR,respeetively, are shown in Fig. 1.

A first and a second time element device or relay which may. be of the well-known thermal type, designated by the reference charactersTER and ATER, respectively, are also shown in Fig. 1. Each of the devices TER and ATER is provided with a back contact 46 or 50, respectively,

which is normally closed, while the correspondingdevicc is deenergized, but becomes opened when the corresponding device becomes energizedand-is then slow 'to close when the corresponding device becomes deenergized.

'Each of the devices TER and ATER is also provided with a front contact or 49, respectively, which is normally open, but which becomes closed upon the lapse of a corresponding measured period of time after the corresponding device becomes energized. First and second timing stick relays are also shown, designated by the reference characters TESR and ATESR, respectively.-

I shall assume that the time setting of the TER-TESR relay combination is that which is required for a distance equal to the sum of the lengths of the track sections CT and ET. I shall also assume that the time setting of the ATER-ATESR relay combination is that which is required for-a distance equal to the length of track sectibmAT, which is shorter than the sum of the lengths of sections CT and BT.

Each of the approach locking relays 2LSR and A2LSR has pickup and stick circuits which include a front contact of relay ZRP and an nr contact of lever 2V. An energizing circuit for each of the time element devices or relays TER and ATER also includes a front contact of relay 2RP and an nr contact of lever 2V. The energizing circuit for time element device or relay TER includes back contacts of relays 2LSR and TESR, and an energizing circuit for time element device or relay ATER likewise includes back contacts of relays A2LSR and ATESR. As shown in Fig. 1, relay 3LR is energized only while relay 3TR and approach locking relays 2LSR and A2LSR are all energized.

Referring now to Fig. 2 of the drawings, a slow release signal control relay, designated by the reference character ZDHR, for signal 2D, is controlled by front contacts of relays ATR and BTR. A slow release directional stick relay, designated by the reference character 2DSR, is controlled by relays BTR and ZDHR. A second slow release directional stick relay, designated by the reference character ESR, is controlled by relays 3TR and ATR to become energized when a train moves from section 3T onto section AT.

Approach relay ZAR is here of the polarized type, energized by current of normal polarity while the three approach track sections are unoccupied, but controlled to become energized by current of reverse polarity when any one of the approach sections CT, BT and AT becomes occupied by a westbound train. A repeater relay, designated by the reference character APR, is controlled by a front contact of relay ZAR, and is of a slow releasing type, so that it will retain its front contacts closed during the intervals between energization of relay 2AR by current of normal polarity and energization of relay ZAR by current of reverse polarity.

Only one approach locking relay, designated by the reference character ZLSR, is required in the arrangement shown in Fig. 2. One of the pickup circuits for relay 2LSR includes a normal polar contact 36 of relay 2AR in addition to a front neutral contact 37 of relay 2AR. A first time element relay TER, in Fig. 2, is controlled by a reverse polar contact of relay ZAR and by a from point of a contact 56 of relay APR. Relay TER may also at times be controlled, through the back point of contact 56 of relay APR, over a portion of the energizing circuits for a second time element device or relay ATER. Relay SLR is here controlled by only relays 3TR and 2LSR.

I shall assume that the time setting of relay TER, in Fig. 2, is that which is required for a distance equal to the sum of the lengths of track sections CT and BT, and that the time setting for relay ATER is that which is required for a distance equal to the length of track section AT, which is shorter than the sum of the lengths of sections CT and BT.

Having described, in general, the arrangement and con trol of the various parts of apparatus embodying my invention, I shall now describe the circuits and operation in detail.

As shown in the drawings, all parts of the apparatus are in the normal condition, that is, all track sectionsare vand 37 ofrelay 2AR.

unoccupied, 'and therefore all track relays are energized; switch 3 is in its normal position; signal mechanism 2G is deenergized, and-is'therefore in the stop position; signal 2D is displaying an approach proceed indication; each of the levers 2V and 3V is in its n position; relays 2AR, 2LSR,'A2LSR, 3LR and 2RP in Fig. l are energized; relay 2AR in Fig. 2 is energized by current of normal polarity; mechanism 2DGis energizedfor controlling signal 2D to display an advance proceed indication; relays 2DHR, 2LSR, APR, 3LR and 2RP in Fig. 2 are energized; relays TER, TESR, ATER and ATESR in Fig. 1 are deenergized; and relays ESR, 2DSR, TER and ATER in Fig. 2 are deenergized.

As shown in each of the-Figures 1 and 2, relay 2RP is energized by a circuit passing from terminal B of battery Q, through'contact's g and y of signal 2, and the winding of relay 2RP to terminal N of battery Q.

As shown in Fig. l, relay 2AR is energized by a circuit passing from terminal B, through contacts 5 and 6 of relays CTR and BTR, respectively, and the winding of relay 2AR to terminal N.

-Relay2LSR in Fig. 1 is energized by a stick circuit and by a first pickup circuit. The first pickup circuit passes from terminal B, through contact 7 of lever 2V, contact 8 of relay 2RP, contact.9 of relay 2AR, and the winding of relay 2LSR to terminal N. The stick circuit for relay 2LSR is the same as the pickup circuit just traced except that it'includes the front point of contact 10 of relay 2LSR instead of contact 9 of relay 2AR.

. Relay AZLSR in Fig. 1 is also energized by a stick circuit and a first pickup circuit. The first pickup circuit for relay A2LSR passes from terminal B, through contact 11- of lever 2V, contact 12 of relay 2RP,, contact 13 of relay 2LSR, contact 14 of relay ATR, and the winding of relay AZLSR to terminal N. The stick circuit for relay AZLSR ,is the same as the pickup circuit just traced except that it includes the front point of contact 15 of relay.A2LSR instead of contact 14 of relay ATR.

Relay 3LR in Fig. 1 is energized by a circuit passing from terminal B, through contacts 16, 17 and 18 of relays 3TR, 2LSR, and A2LSR, respectively, and the winding of relay 3LRto,terminal N. Contact 19 of relay .3LR and contacts 20 and 21 of lever 3V are closed in a normal operating circuit for switch mechanism 3M for switch 3. As shown in Fig. 2, relay 2DHR is energized by a circuit passing from terminal B, through contacts 24 and 25 of relays ATR and BTR, respectively, and the winding. of relay 2DHR to terminal N. With relay 2DHR energized, mechanism 2DG for signal 2D is energized by a circuit passing from terminal B; through contact 26 of relay 2DHR, and mechanism ZDG to terminal N.

Relay 2AR in Fig. 2 is energized by current of normal polarity passing from terminal B, through-the front points of contacts 27 and 28 of relays CTR and 2DHR, respectively, the winding of relay 2AR, and the front points of contacts 29 and 30 of relays 2DHR and CTR, respectively,

, vto terminal N. With relay 2AR energized, relay APR is energized by a circuit passing from terminal B, through contact 33 of relay 2AR, and the winding of relay APR to terminal N.

Relay 2LSR in Fig. 2 is energized by both a stick circuit of relay 2AR, and the winding of relay 2LSR to terminal .N. The stick circuit for relay 2LSR is the same as the fpickup circuit just traced except that it includes the front point of contact 38 of relay 2LSR instead of contacts 36 7 Relay 3LR is here energized by a circuit passing from terminal B, through contacts 39 and 40 of relays 3TR and 2LSR, respectively, and the winding of relay 3LR to terminal N. Contact 19 of relay 3LR and contacts 20 ll'l d: 21 of lower 3V'are here closed in a normal operatingcircuit for switch mechanism 3M, as in Fig. 1.

I shall assume that, with the apparatus arranged as shown in Fig. l, a leverman or dispatcher moves'lever 2V to its f position to clear signal 2 for a westbound train to move past switch 3. Signal mechanism 26 will therefore be energized by a circuit passing from terminal B, through contact 41 of lever 2V, and mechanism 2G to terminal N, for controlling signal 2 to display an approach proceed or a clear. proceed indication as selected by means not shown in the drawings.

Lever 2V, upon being moved away from its 11 position toward the 1 position, opens its contacts 7 and 11, there- 1 by deenergizing relays 2LSR and AZLSR.

With signal 2 displaying either an approach or a clear proceed indication, contact y or contact g of this signal will be open, and therefore relay 2RP will bedeenergized.

With relays 2LSR and A2LSR deenergized, contacts 17 and 18, respectively, of these relays will be open, and therefore relay 3LR will be deenergized. With relay 3LR deenergized, contact 19 will be open in the operating circuits for switch mechanism 3M, and therefore mechanism 3M could not now be energized for moving switch 3 to the reverse position.

I shall assume further that a westbound train enters section CT, thereby deenergizing relay CTR, which, in turn, at its contact 5, opens the circuit for relay 2AR, causing relay 2AR to be deenergized. When the train enters section ET, the circuit for relay 2AR will be opened at another point by contact 6 of relay BTR. When the train enters section AT, relay ATR will be deenergized, and therefore its contact 14 will be opened in the pickup circuit previously traced for relay A2LSR, which is, however, already deenergized on account of the opening of contact 11 of lever 2V. When the train enters section 3T, relay 3TR will become deenergized, and therefore its contact 16 will open the circuit forrelay 3LR at a third point. If, now, while the train is on section 3T, a leverman or dispatcher returns lever 2V to its n position, contact 41 of lever 2V will open the circuit previously'traced for signal mechanism 26, causing mechanism 2G to be deenergized and relay 2R1 to in turn again becomeenergized by its circuit previously traced. A second pickup circuit will now be completed for energizing relay 2LSR, this circuit passing from terminal B, through contact 7 of lever 2V, contact 8 of relay 2RP, contact 42 of relay 3TR, and the winding of relay 2LSR to terminal N. With relay 2LSR energized, a second pickup circuit will also be completed for relay A2LSR, this. circuit passing from terminal B, through contact 11 of lever 2V, contact again in the normal condition, and that, again, a leverman or dispatcher moves lever 2V to its f position for clearing signal 2. I shall vassume further that a westbound train enters section CT, and that while the train is moving over section CT or section ET, the leverman or dispatoher returns lever 2V to its 11 position, thereby controlling signal 2 to again display the stop indication, and causing relay ZRP to again become energized.

With the train on section CT or, BT, relay 2AR will be deenergized, and therefore its contact 9 will be open in the first pickup circuit traced for relay 2LSR. Relay 2LSR will therefore remain deenergized when lever 2V is returned to its n position, and an energizing circuit will be completed for time element device or relayTER, this circuit passing from terminal B, through contact 7 of lever 2V, contact 8 of relay 2RP, back point of contact 10 of relay 2LSR, the back point of contact 44 of relay TESR, and the control element of d'eviceTER to terminal N. Device TER will then open its contact 46 and, upon the lapse of a measured period of time, will close its contact 45, thereby completing a pickup circuit for ,relay,.TESR,, this circuit passing from terminal B, through contact 45 ofrelay TER, and the winding of relay TESR to terminal N. Relay TESR, upon becoming energized, will complete its own stick circuit, which is the same as the energizing circuit previously traced for relay TER except that it includes the from point of contact 44 of relay TESR instead of the back point of this contact.

Relay TESR,UPO11 opening its contact 44, at the back point, deenergizes relay TER, so that contact 46 of relay TER then again becomes closed, upon the lapse of a brief period of time. Another, or third, pickup circuit will now be completed for relay ZLSR, this circuit passing from terminal B, through contact 7 of lever 2V, contact 8 of relay ZRP, contact 46 of relay TER, contact 4-7 of relay T ESR, and the winding of relay ZLSR to terminal N. Relay 2LSR, upon becoming energized, opens its contact 10 at the back point, thereby deenergizing relay TESR.

1f the westbound train should stop on section CT or section BT, or if it should move so slowly that energization of relay ZLSR by its third pickup circuit would be effected by relay T ER before the train enters section AT,-relay AZLSR would become energized by its first pickup circuit, previously traced, as soon as relay 2LSR closed its contact 13. Relay SLR would therefore become energized upon the lapse of only the period of time determined by relay TER.

It follows that, in this event, the approach locking of relay .3LR is released after only a short period of time, determined by relay TER, instead of after a long period of time as determined by the operating time of both relays TER and ATER.

If, however, the train enters section AT before relay AZLSR has become eenergized, contact 14 of relay ATR would be open in the pickup circuit first traced for relay A2LSR, and therefore relay AZLSR would not become energized as soon as relay ZLSR becomes energized.

When relay 2LSR closes its contact 13, an energizing circuit would, however, be completed for time element relay ATER, this circuit passing from terminal B, through contact 11 of lever 2V, contact 12 of relay 2RP, contact 13 of relay ZLSR, back point of contact 15 of relay A2LSR, backpoint of contact 48 of relay ATESR, and the winding of relay ATER to terminal N. Relay ATER would then open its contact 50 and, upon the lapse of a measured period of time determined by relay ATER,

contact 49 of relay ATER would become closed and thereby complete a pickup circuit for relay ATESR, this circuit passing from terminal B, through contact 49-of relay AT ER, and the winding of relay ATESR to terminal N. Relay ATESR, uponbecoming energized, would complete its own stick circuit, which is the same as the I contact 11 of lever 2V, contact 12 of relay ZRP, contact 13 of relay ZLSR, contacts 50 and 51 of relays ATER and ATESR, respectively, and the winding of relay AZLSR to terminal N. Relay AZLSR, upon becoming energized,

will open its contactlS at theback point, thereby deenergizing relay ATESR. Relay AZLSR will also complete its own stick circuit previously traced through the front point of its contact 15,

The approach locking of relay 3LR by relays ZLSR andAZLSR is now released after a time interval deter- 8 mined'by both relays TER' and ATERg This releasing time is therefore longer than the release time determined in the previous example given, in which relay ZLSR became energized before the train entered section AT.

I shall next assume that, with all parts of the apparatus again in the normal condition, the leverman or dispatcher again moves lever 2V to its f position for energizing mechanism 2G tocontrol signal 2 to again display a proceed indication.

I shall assume further that a westbound train proceeds over sections CT and BT, and stops on section AT because the engineman desires to move over switch 3 in its reverse position instead of in the normal position. The leverman or dispatcher will then return lever 2V to its n position, causing signal mechanism 26 to returnto the stop position .and thereby causing relay 2RP to in turn again become energized.

With sections CT and BT unoccupied, relay 2AR will be energized by its circuit previously traced. Relay 2LSR will therefore become energized at once by its pickup circuit first traced, when lever 2V is returned to its n position. Relay ATER will now become energized by its circuit previously traced, and, upon the lapse of a measured period oftime, relay ATESR will become energized. Relay A2LSR will therefore become energized by its third pickup circuit, previously traced, upon the lapse of only the period of time determined by relay ATER, which is shorter than the time required when the leverman returned signal 2 to stop while a train was moving rapidlyover section CT and BT so that the train entered section AT before relay AZLSR became energized.

I shall now assume that, instead of a westbound train moving over sections CT and BT, an eastbound train is to move over switch 3 in its reverse position. A leverman or dispatcher will therefore effect operation of switch 3 to its reverse position by moving lever 3V to its r position, thereby completing a reverse operating circuit for mechanism 3M, passing from terminal B, through contact 19 of relay 3LR, contact 23 of lever 3V, mechanism 3M, and contact 2201 lever 3V to terminal N.

I shall assume further that the train, upon moving over switch 3 in its reverse position, stops on section AT, preparatory to reversing its movement. I shall assume still further that the leverman controls signal 2 to display a proceed indication for the train to move back over switch 3 in the reverse position, whereas the engineman desires to go over switch 3 in its normal position. It is therefore necessary for the leverman to now return lever 2V to the 11 position. With sections CT and BT unoccupied, relay 2AR will be energized, as previously described. and therefore relay ZLSR will now become energized without the delaytime imposed by relay TER. The approach locking will therefore be released upon the lapse of only the time determined by relay ATER, as previously described for a westbound train which had stopped on section AT.

It follows that, with apparatus arranged as shown in Fig. 1, my invention provides means for releasing aproach locking in a short time if a leverman or dispatcher changes the indication of a home signal from a proceed indication to a stop indication after a train has arrived adjacent signal 2 and stopped on the approach section AT, whereas, if the leverman or dispatcher changes the indication of a home signal from proceed to stop whilea train is approaching at high speed at a longer distance away, a longer time, determined by both relays TER and ATER, will be required for the release of the approach locking.

I shall assume that, with apparatus arranged as shown in Fig. 2, a leverman or dispatcher moves lever 2V to the position. Mechanism 26 will then be operated, and relay 2R1 will become deenergized, as previously described in connection with Fig. 1. Contact 34 of lever 2V will open the stick andfirst pickup circuits for relay senses when levenzV is moved away from its ftp'o'sition towarditsf position, and therefore relay 2LSR will be 'deenergized, and, in turn, relayf3LR will be deen'ergized, becausef the opening of contact 40 of relay ZLSR. With relay 3LR deene'rgized, its contact 19 will be open in 'e operating 3 circuits for switch mechanism 3M, and

therefore switch 3 cannot be'moved. v "I shall assume further that a westbound train new enterssection CT. Relay 2AR,wi1l therefore be energized by current of reverse polarity in a circuit which is the same "as the circuit traced for energizing this relay by'current of normal polarity except that it includes the back points of contacts 27 and 30 of-rel'ay CTR instead of the front points jof-these'contacts. With relay ZAR energized by current of reverse polarity, its contact 36 will be open in the pickup circuit first traced for relay ZLSR. Relay APR will, however, remain energized by its circuit previously traced. With relay 2AR energized by current 'of reverse polarity, and with relay APR energized,

relayTER becomes energized as soon as the westbound train 'enterssection CT, althoughlever 2V is still in its 1 position. Operation of relay TER is therefore started for closing its contact 57 upon the lapse of a measured period of time.

i QWhen-"the westbound train enters section BT, 'contact 25'of relay BTR will open the circuit for relay ZDHR which is slow releasing'and which will therefore not open same as thelpickup circuit just traced except .that it includes contact 54 of relay ZDSR instead of the front point of contact 53 of'relay ZDHR. Upon the lapse of a brief period of time, the contacts of relay 2DHR will bercleased, and therefore a second stick circuit will be completed forrelay 2DSR,-this circuit passing from termian ['13, through-the back point of contact 53 of relay 2DHR, contact 54 of relay ZDSR, and thewinding of relayv ZD SR to terminal N;

With relay 2DSR energized and'relay ZDHR deenergized, asecond circuit is now completed for energizing relay ZAR bycurrent of 'reverse polarity, this circuit passing from terminal B, through contact 31 ofrelay 'ZDSR, back point of contact29 of relay ZDHR, winding of relay ZAR, back point of contact 28 of relay ZDHR, andcontact32 ofirelay ZDSR to terminal Since relay ZDHR is controlled by relays. ATR and BTR,'it follows that relay ZAR will remain energized by current of reverse polarity as long as the train remains on any, portion of sections, BT and AT, as well as while the train isj on section CT.

I shall now assume still further'that, while the train is on one of the sections CT BT or AT, a leverman or dispatcher returns lever 2V to its 11 position. .Mechanism 2G will then be returned to the stop position, and relay 2R1 will again be energized, as previously described.

1 As soon ,as the westbound train enteredsection CT,

causing relay 2AR to become energized by current of reverse polarity, relay .TER became energized by' a circuit passing from terminal B, through contact 55 of relay 2AR, front point of contact 56v of relay APR, and the winding of relay TER to terminal N. The operation of relay TER therefore began at thetime the train entered section CT, instead of not until lever 2V was returned to its n position, as with the apparatus arranged as in Fig. 1. Upon the lapse of the remaining portion of the measured period of time for operating relay TER, after lever 2V tact 57, thereby completing an energizing circuit for relay lever"2V contact 35 of relay ZRP, back point of can:

tact 38 of relay 2LSR,'contact 57 of'relay TER, and the winding of relay ATER to terminal N.

With relay ATER energized, another, or third,pick'+ up circuit will be completed for relay ZLSR, upon the lapse of a further measured period oftime, this circuit passing from terminal B, through contract 34 of lever 2V, contact 35 of relay ZRP, contact 59 of relay ATER, and the winding of relay 2LSR to terminal N. 'Th approach locking of relay SLR, as effected by relay 2LSR', will therefore be released upon the lapse of a measured period of time as determined by relay ATER 'and the portion of the time remaining for the operation of relay TER' atthe time the leverman returns lever 2V to the 12 position. 1 If the leverman or dispatcher does not return lever 2V to the n position until after the train h'asstopped adjacent signal 2, sufiicient time will have elapsed for relay TER to have closed its front contact 57, and therefore relay ATER'will become energized'at once. The release of the approach locking of relay 3LR, after lever 2V is thus returned to its n position, will thereforebe effected upon the lapse of a measured periodof time dependent upon only relay ATER, which is shorterth'an would be required if lever 2V were' returned to its 'ri position while' the train is moving rapidly over section CT orfsection'fBTsothat the measured period of time for relay TER to close its-contact 57 has ;not elapsed before'tlie return of lever 2V' t o its n pos'ition.

I shall now' -ass'urhe' that a,'l'ever'man or dispatcher reverses switch 3, as previously described, for an eastbound train to] move from an auxiliary track onto the main tracln'When the eastbound train enters section 3T; relay ESR' will become energized by a pickup circuit passing f romt'erminal B, 'through contact 61 of relay 3TR, front'point of contact'62 of relay ATR, and'the im'nding of'rel'ay ESR to terminal N. Relay ESR, upon becoming energized, will complete a stick circuit which is the same as the pickup circuit-just traced except that it includes contact 63 of relay ESR instead of the front point of contact 62 of relay ATR. When the train enters section.-'AT-, causing the contacts of relayATR to become released, a secon d stick circuit will'be completed for relay ESR, passing from terminal B, through the back pointof contact 62of relay'ATR, contact63 of relay ESR, and the winding'of relay ESR= to terminal N. If'the leverman or dispatcher now clears signal-2 for the train to return over switch'3 reversed, whereas the en'gineman' desires toumove over switch 3 normal, and if the leverman .then returns lever 2V to its n position; relayATER' will'at once become energized by a'cin cuit passing fr'omterm'inal'B, through contact 34;of le'ver ZVicontact 35'ofrelay ZRP, .back point of contact 38 of reIay'ZLSR, contact 58 of relay ESR, and the winding of relay ATER to terminal N. It follows that,funder these conditions, the release ofqthe, approach locking of relay 3LR Willibe efiecteduponthe lapse of only the period of time determined byrelay ATER instead of by both relays TER and ATER. I v

From the foregoing description of operation of apparatus arranged as in the-modifiedform' shown in Fig. .2,

'ATER, after lever 2V is returned to the 11 position, before release .ofthe. approach ,locking can be. eifected ,-,If, however, .the leverman does. not return lever 2V, ,'t:;t h n position until after relay TER has completed its operation and closed its contact 57, the approachlocking will then be released upon the further lapseof only the time required for relay ATER to be operated, for closing its contact 59. It is to be understood that the time of operation. of relay TER is selected so that it will have expired by the time the train has left sectionB'L- Therefore, if the leverman returns lever 2V to the, n positionat any time after the train has left section BT,-as .when it has stopped at signal 2, the approachlocking will be released at the expiration of the time required foropera tion of only relay ATER after the return of lever 2V to its 11 position.

It follows that apparatus embodyingmy invention, eitheras shown inFig. 1, or as in the modified form shown in Fig. 2, provides means for releasing approach locking upon the lapse of a short period of time if a leverman or dispatcher returnsleverZV to the 11 position after a train has stopped at the home signal 2, but that a longer time is required for the release of approach lockingif the leverman returns lever 2V to the )1 position soon after a westbound train, moving at high speed, enters the approach zone which includes sections CT, BTand AT.

In the modified form of apparatus shown inFig. 2, a

second circuit is provided for energizingrelayTER,

through the baek point of contact 56 of relay APR, after a leverman or dispatcher has returned lever 2V to its n position, if relay 2DSR has failed to become energized when a westbound train entered section BT, or .if relay ESR has failed to become energized in response to-an eastbound train. Without this second circuit for energizing relay TER in the event of such a failure of relay ZDSR or relay ESR to become energized, the time element relays would remain deenergized until after the cause of the failure had been removed by a maintainer orother authorized person. In the meantime, approach locking relay ZLSR would remain deenergized,,causing relay SLR to also remain deenergized, and therefore, switch 3 would remain locked and cause anunnecessary train delay.

In the event of failureofrelay 2DSR,.or relay ESR to become energized, there is no need for retaining thcswitch in the locked condition after the lapse of a period ,of time determined by both relays TER and ATER, .asinitiated, by the second energizing circuit for relay .TER through the back point of contact 56 of relay APR.

I shallassume that, as previously described,-with apparatus arranged as shownin Fig. -2, a leverman or. a dispatcher moves lever 2V to its 1 position to .clearsignal 2 for a westbound train, thereby deenergizing relay,.2LSR,

and that a westbound train then enters section CT, causing r.

relay 2AR to become energized by' current of-reverse polarity. I With relay 2AR energized by current of reverse polarity, the first energizing circuit for relay TER, previously traced through the front point of contact. 56:01?

relay APR, will be completed, and will start operation of t relay'TER.

When the train enters section BT, relay 2DH'R will become deenergized, thereby opening the circuit, previously described, including the back-points of-contacts27 and 30 of relay CTR, for energizing relay ZAR by current of reverse polarity. I shall assume further -that relay ZDSR has failed to become energized when the train entered section ET. The second circuit, previouslytraced, including contacts 31 and 32 of relay ZDSR, for energizing relay 2AR by current of reverse polarity, will therefore i of relay ZRR, back point of contact 38 of relay 2I.;S R, baelr point of contact 56 of relay APR, and the winding of relay TER, to terminal N. Upon the lapse of a measured period of time as determined by relay TER, relay ATER will become energized, and upon the lapse of a further measured period of time as determined by relay ATER, relay 2LSR will become energized by its third pickup circuit and will release the locking of switch 3, as previously described. 7

I shall now assume that a train moves eastward off of the auxiliary track, over switch 3 reversed, and that relay ESR fails to become energized. If a leverman or a dis patcher then clears signal 2 for the train to move westward, .and if he then again returns lever 2V to its 11 position, relay ATER will not at once become energized as previously described, because contact 58 of relay ESR has not become closed.

With the train on section AT, ,relay ZDHR will be deenergized, and therefore relay 2AR will in turn also be deenergized. Relay TER will therefore become energized by, its second circuit, including the back point of contact 56 of relay APR, as previously described in connection with an assumed failure of relay ZDSR to become energized. As in case of a failure of relay ZDSR, relay ZLSR will then become energized upon the lapse of a measured period of time determined by both relay TER and relay ATER.

I have described the operation of the apparatus embody.- ing my invention for a few typical trafiic movements, It is believed that in view of such description, taken with the accompanying drawings, the operation of the apparatus for any other possible trafiic movement can be readily traced without further detailed description.

Although I, have herein shown and described only two .forms of apparatus embodying my invention, it is under,- stood that various changes and modifications may be made therein within the scope of the appended claims Without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. Inapproach locking control apparatus for a stretch of railway track which is provided with a traflic governing device and a home signal for governing trafficmovements in a given direetion past said trafiic governing device and also an approach signal in the rear of said home signal for governing trafiic movements in said given direction toward said home signal, said stretch of track divided into a first approach section in the rear of said approach signal and a second and a third approach section between said approach signal and said home signal with said third approach section adjacent said home signal, the combination comprising, an approach locking relay, time element means, control means manually operable from a normal condition to a control condition for controlling said home signal to display a proceed indication, means controlled by a train approaching said home signal. in said given direction-and by said control means if said. control means is restored to its normal condition while said train,is on said first approach section for operating said time element means for energizing said approach locking relay ,upon the lapse ofa given measured period of time after said control means is restored to its normal condition, means controlled by a train approaching said hometsignal in said given direction and by; said control means if saidcontrol meansis restored to its normal condition while said train is on said third approach section for operating ,saidtime element means for energizing said approach locking relay upon the lapse of a second measuredperiod of time. which is shorterthan said given measured period of tim,e, and means including a contact of said approach lockingrelay for controlling said traffic governing device.

2. In approach locking control apparatus fora stretch of railway track which is providedivith .a traffic governing device anda. home signal for governing traific movements in a given direction past said trat l'ie governing device uid also an approach signalin the rear of said homesignal for l3 governing traific movements in said given direction toward said home signal, said stretch of track divided into a first approach section in the rear of: said approach signal and a second and a third approach section between said approach signal and said home signal with said third approach section adjacent said home signal, the combination comprising, an approach locking relay, control means manually operable from a normal condition to a control condition for controlling said home signal to display a proceed indication, means controlled by a train approaching said home signal in said given direction and by said control means if said control means is restored to its normal condition while said train is on said first approach section for energizing said approach locking relay upon the lapse of a givenmeasured period of time after said control means is restored to its normal condition, means controlled by a train approaching said home signal in said given direction and by said control means if said control means is restored to its normal condition while said train is onsaid third approach section for energizing said approach locking relay upon the lapse of a second measured period of time which is shorter than said given measured period of time, and means including a contact controlled by said approach locking relay for controlling said trafiic governing device.

3. .In approach locking control apparatus for a stretch of railway track which is provided with a signal for governing trafiic movements in a given direction, said stretch of track divided into a first and a second and also a third approach section arranged in the order named in the rear of said signal with said third approach section adjacent said signal, the combination comprising, approach locking means, control means manually operable from, a normal condition to a control condition for controlling said signal to display a proceed indication, means controlled by a train approaching said signal in said given direction and by said control means if said control means is restored to its normal condition while said train is on said first or said second approach section for energizing said approach locking means upon the lapse of a given measured period of time after said control means is re stored to its normal condition, means controlled by a train approaching said signal in said given direction and by said control means if said control means is restored to its normal condition while sa'id train is on said'third approach section for energizing said approach locking means upon the lapse of a second measured period of time which is shorter than said given measured period of time, and traflic governing means controlled by means including said approach locking means in its energized condition.

4. In approach locking control apparatus for a stretch of railway track which is provided. with a signal for governing traflic movements in a given direction, said stretch of track divided into a first and a second approach section with said second approach section adjacent said signal and said first approach section in the rear of said second approach section, the combination comprising, approach locking means, control means manually operable from-a normal condition to a control condition for controlling said signal to display a proceed indication, means controlled by a train approaching said signal in said given direction and by said control means if said control means is restored to its normal condition while said train is on said first approach section for energizing said approach locking means upon the lapse of a given measured period of time after said control means is restored to its normal condition, means controlled by a train approaching said signal in said given direction and by said control means if said control means is restored to its normal condition while said train is on said second approach section for energizing said approach locking means upon the lapse of a second measured period of time which isshorter than said given measured period of time, and trafiic governing means conits 'energized condition.

trolled byv means including said approach locking means in 5. In approach locking control apparatus for a stretch of railway track which is provided with a signal for governing trafiic' movements in a given direction, said stretch of trackdivided into a first and a second approach section with said second approach section adjacentsaid signal and said first approach section in the rear of said second approach section, the combination comprising, approach locking means, control means manually operable from a normal condition to acontrol condition for controlling said signal to display 9. proceed indication, means controlled by a train approaching said signal in said given direction and by said control means if said control means is restored to its normal condition while said train is on said first approach section for energizing said approach locking means upon the lapse of a given measured. period of time after saidcontrol means is restored to its normal condition if .said train has not yet entered'said second approach section,'means controlled by a train approaching said signal in said given direction and by said control means if said control means is restored to its normal condition while said train is on said first approach section for energizing said approach locking means upon the lapse of a second measured period of time which is longer than said given measured period 'of time if said train enters said second approach section before expiration of said given measured period of time,means controlled by a train approaching said signal in said given direction and by said control means if said control means is restored to its normal condition while said train is on said second approach section'for energizing said approach locking means upon the lapse of a third measured period of time which is shorter than said second measured period of time, and 'trafiic governing means controlled by means including said approach locking means in its energized condition.

6. In combination, a stretch of. railway track provided with a traffic governing device, a signal for governing trafiic movements in a given direction past said tratfic governing device, a first and a second section of said track in the rear of said signalvwithsaid second section adjacent said signal and said first section in the rear of said second section, a first and a second approach locking relay, a first and a second time element device, a control device manually operable from a normal position to a controlposition for controlling said signal to display a proceed indication, a first trafiic responsive device for said first section normally energizedbut becoming deenergized in response to a train occupying said first section, a second trafiic responsive'device for said second section normally energized but becoming deenergized in response to a train occupying said second section, a first pickup circuit and a stick circuit for said first approach locking relay controlled by said control device in its normal position and said first pickup circuit also controlled by said first trafi'ic responsive device in the energized condition, an energizing circuit for said first time element device controlled by said control device in its normal position and by a back contact of said first approach locking relay, another pickup circuit for said first approach locking relay controlled by said control device in its normal position and by a contact controlled by said first time element device to become closed when said first time element device has been energized for a given measured period of time, a first pickup circuit and a stick circuit for said second approach locking relay controlled by a front contact of said first approach locking relay and by said control device in its normal position and said first pickup circuit for said second approach locking relay also controlled by said second trafiic responsive device in the energized condition, an energizing circuit for said'second time element device controlled by a front contact of said first approach locking'relay and by said controldevicein its normal position and also by a back contact of saidsecondapproachtlocking relay, another pickup circuit for said second approach locking relay controlled by said control device in its normal position and by a contact closed in response to energization of said second time element device a second given measured period of time, andmeans including front contacts of said first and second approach locking relays for controlling said traffic governing device.

7. In combination, a railway track, a signal for governing trafiic movements in a given direction on said track, a first and a second portion of said track in the rear of said signal with said second portion adjacent said signal and said first portion in the rear of said second portion, a first traffic responsive device normally energized but becoming deenergized in response to a train entering said first portion, a second traflic responsive device normally energized but becoming deenergized in response to a train entering said second portion, a first and a second approach locking relay, control means manually operable from a normal condition to a control condition for controlling said signal to display a proceed indication, a stick I circuit and a first pickup circuit for siad first approach locking relay each controlled by means including said control means in its normal condition and said first pickup circuit also controlled by said first trafiic responsive device in the energized condition, a stick circuit and a first pickup circuit for said second approach locking relay each controlled by means including a front contact of said first approach locking relay and said first pickup circuit for said second approach locking relay also controlled by said second' trafiic responsive device in the energized condition, a first and a second time element device energizedby means including said first and second approach locking relays respectively in the deenergized condition and said control means in the normal condition and said second time element device also controlled by a front contact of said first approach locking relay, an-' other pickup circuit for each of said first and second approach locking relays controlled by means including said first and second time element device respectively in the energized condition, and trafiic governing means controlled by means including front contacts of said first and second approach locking relays.

8. In combination, a stretch of railway track provided with a trafiic governing device, a home signal for governing traffic movements in a given direction on said' track past said traflic governing devicepan approach signal in the rear of said home signal for governing traffic movements in said given direction toward said home signal, a first approach section of; said tra'ckin' the rear of said approach signal, a second and a third approach section of said track between said approach signal and saidhome signal with saidthird approach section adjacent said home signal, a polarized approach relay normally energized by current of normal polarity but becoming e nergizedby current of reverse polarity in response to a train moving in said given direction over said approach sections, an approach locking'relay, afirst and'a second time element device, means including a'reversepolar contact of said approach relay for e'nergiziiigsaid first time element device, control means manually op'erable from a normal condition to a controlcoridition'fo-r controlling'said home signal'to display a proceed indication, a stick circuit and a first pickup circuit for said approach locking relay controlled'by means including said control means in the normal condition and said first pickup circuit also controlled by means including a normal polar contact of said polarized approach relay, an energizing circuit for said second time element device controlled by means including said control means in its normal condition and a back contact of said approach'locking relay and also'said first time element device in the energized condition, another pickup circuit for saidapproach locking relay controlled by means including said second time element device in the'energized condition, and'rneans including a front contact of said approach locking relay for controlling said trafiic governing device.

9. In combination, a railway track, a signal for governing traflic movements in a given direction on said track, an approach portion of said track in the rear of said signal, a polarized approach relay normally energized by'current of normal polarity but becoming energized by current of reverse polarity in response to a train moving over said approach portion of said track, a first and a second time element device, means including a reverse polar contact of said approach relay for energizing said first time element device, control means manually operable from a normal condition to a control condition for controlling said signal to display a proceed indication, an approach locking relay, a stick circuit and a first pickup circuit for said approach locking relay controlled by means including said control means in the normal condition and said first pickup circuit also controlled bymeans including a normal polar contact of, said approach relay, energizing means for said second time element device controlled by means including said control means in its normal condition and a back contact of said approach locking relay and also said first time element device in the energized condition, another pickup circuit for said approach locking relay controlled by means including said second time element device in the energized condition, and tratfic governing means controlled by means including a front contact of said ap proach locking, relay.

10. In combination, a stretch of railway track provided with a trafiic governing device, a signal for gov erning trafficmovement in a given direction past said trafiic governing device, a first and a second portion of said track in the rear of said signal with said second portion adjacent said signal and said first portion in the rear of said second portion, a first and a second approa'ch locking relay, a first and a second time element device, a control device manually operable from a normal position to a control position for controlling said signal to display a proceed indication, a first traflic responsive device for said first portion of said track normally energized but becoming deenergized in response to a train occupying said first portion, a second traffic responsive device for said second portion of said track normally energized but becoming deenergized in response to'a train occupying said second portion, a first pickup circuit and a stick circuit for said first approach locking relay controlled by means including said control device in its normal position and said first pickup circuit also controlled by said first trafiic responsive device in the energized condition, an energizing circuit for said first time element device controlled by means including said control device in" its normal position and a back contact of -said'first approach locking relay, another pickup circuit for said first approach locking relay controlled by means including a contact controlled by said first time element device to become closed when said first time element device has been energized for a given measured period of time, a first pickup circuit and a stick circuit for said'second approach locking relay controlled by means including a front contact of said first approach locking relay and said first pickup circuit for said'second approach locking relay also controlled by said second traffic responsive device in the energized condition, an energizingcircuit for said second time element device controlled by means including a front contact of said'first approach locking relay and a back contact of saidsecond approach locking relay, another pickup circuit for said second approach locking relay controlled by means'including a contact closed in response to energization of said second time element device'a" second measured period of time, and means including front contacts of said first and second approach locking relays for controlling said trafiic governing device;

11. In combination, a railway track, a signal for governing trafiic movement in a given direction on said track, a first and a second time element device, control means including means responsive to a train approaching said signal in said given direction within a given distance in the rear of said signal for energizing said first time element device, a directional stick relay, a pickup circuit for energizing said directional stick relay in response to a train moving oppositely to said given direction from a first portion of said track in advance of said signal to a second portion of said track in the rear of said signal, a stick circuit for then retaining said stick relay energized while said train occupies said second portion of said track, an approach locking relay, manual control means manually operable from a normal condition to a control condition for controlling said signal to display a proceed indication, a stick circuit and a first pickup circuit for said approach locking relay controlled by means including said manual control means in its normal condition and said first pickup circuit also including traflic responsive means which is normally closed but which becomes opened when a train occupies said track within said given distance in the rear of said signal, energizing circuit means for said second time element device including means controlled by said manual control means in its normal condition and a back contact of said approach locking relay and also including a front contact of said directional stick relay connected in multiple with a contact which is controlled by said first time element device to become closed when said first time element device has been energized for a measured period of time, another pickup circuit for said approach locking relay controlled by means including said second time element device in the energized condition, and trafiic governing means controlled by means including a front contact of said approach locking relay.

12. In combination, a railway track, a signal for governing tralfic movement in a given direction on said track, a first and a second time element device, control means including means responsive to a train approaching said signal in said given direction within a given distance in the rear of said signal for energizing said first time element device, a directional stick relay, a pickup circuit for energizing said directional stick relay in response to a train moving oppositely to said given direction from a first portion of said track in advance of said signal to a second portion of said track in the rear of said signal, a stick circuit for then retaining said stick relay energized while said train occupies said second portion of said track, an approach locking relay, manual control means manually operable from a normal condition to a control condition for controlling said signal to display a proceed indication, a stick circuit and a firstpickup circuit for said approach locking relay controlled by means including said manual control means in its normal condition and said first pickup circuit also including traffic responsive means which is normally closed but which becomes opened when a train occupies said track within said given distance in the rear of said signal, energizing circuit means for said second time element device including means controlled by said manual control means in its normal condition and a back contact of said approach locking relay and also including a front contact of said directional stick relay connected in multiple with a contact which is controlled by said first time element device to become closed when said first time element device has been energized for a measured period of time, another pickup circuit for said approach locking relay controlled by means including said second time element device in the energized condition, other control means including means controlled by said manual control means in its normal condition and a back contact of said approach locking relay and also a contact which becomes closed in response to a train moving from said first portion to said second portion of said track for energizing said first time element device, and traffic governing means controlled by means including a front contact of said approach locking relay.

13. In combination, a railway track, a signal for governing trafiic movements in a given direction on said track, an approach portion of said track in the rear of said signal, a polarized approach relay normally energized by current of normal polarity if said approach portion of said track is unoccupied but becoming deenergized if a train moving oppositely to said given direction enters said approach portion of said track, a directional stick relay, pickup circuit means for energizing said directional stick relay in response to a train moving in only said given direction onto said approach portion of said track, stick circuit means for then retaining said directional stick relay energized while said approach portion is occupied, means controlled by said directional stick relay in the energized condition for energizing said polarized approach relay by current of reverse polarity, a slow release relay controlled by a front neutral contact of said polarized approach relay, time element means, an energizing circuit for said time element means controlled by a reverse polar contact of said polarized approach relay and by a front contact of said slow release relay, signal control means operable from a normal condition to a control condition for controlling said signal to display a proceed indication, an approach locking relay, a stick circuit and a first and a second pickup circuit for said approach locking relay controlled by means including said signal control means in the normal condition, said first pickup circuit also controlled by means including a normal polar contact of said approach relay and said second pickup circuit also controlled by said time element means in an operated condition, a second energizing circuit for said time element means controlled by means including said signal control means in its normal condition and by back contacts of said approach locking relay and said slow release relay, and traflic governing means controlled by means including a front contact of said approach locking relay.

References Cited in the file of this patent UNITED STATES PATENTS 2,013,986 Langdon Sept. 10, 1935 2,334,506 Pflasterer Nov. 16, 1943 2,369,113 Allen Feb. 13, 1945 2,385,179 Allen Sept. 18, 1945

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