US2209225A - Control system - Google Patents

Description

y J. M. EVANS ET AL CONTROL SYSTEM 3 Shets-Sheet 1 Filed Nov. 4, 1936 A T T ORNE Y5.

. s M O I s 2. M u s mmx VMM WPV EM 1.} M M 8 mm mu Y vB E u n 1 i mh um E m \u L 0 CK new y 23, 1940- J. M. EVANS El AL CONTRQL SYSTEM Filed Nov. 4, 1936 3 Sheets-Sheet 3 Patented July 23, 1940 UNITED STATES CONTROL SYSTEM tion of Delaware Application November 4, 1936, Serial No. 109,110

10 Claims.

The present invention relates to protective systems for crossings, or the like, and in particular provides an improved system for actuating crossing signal devices, or the like, in response to the approach of a vehicle to the crossing, characterized in that the distance in advance of the crossing at which a vehicle is effective to actuate the signals is varied in accordance with the speed of approach of the vehicle.

One illustrative application of the control system of the present invention is in connection with the signal devices located at the intersection between a highway and a railway, although it is not limited to such application, but may be embodied in any of a wide variety of protective systems. The signaling devices themselves may take a wide variety of forms, such, for example, as bells, lights, gates, barriers or the like, and, to include all these as well as other and equivalent elements, the signaling elements are hereinafter referred to generically as signal devices.

In conventional rail-highway crossing protective systems, the tracks are divided into signaling sections extending at either side of the crossing, and the entrance of a train or other vehicle into either section is effective to actuate the signaling devices and to maintain them in the actuated condition until the crossing is passed. In the conventional systems, the actuation of signals occurs when the vehicle reaches a predetermined 7 point relative to the crossing, which point is independent of the speed of approach of the vehicle. Consequently, a substantially longer period of warning is given, as to the approach of a slowly moving train than is given to the approach of a rapidly moving train, resulting in unnecessary delays in traflic; and also resulting, in many cases, in a tendency on the part of the highway ratio to disregard the signal devices.

To overcome difficulties of the just mentioned kind, as well as others, it has been proposed to arrange the control systems for the signaling devices in such a way that a rapidly moving train actuates the signals when it is a greater distance from the crossing than does a slowly moving train, the general object being to make more uniform the period of warning in cases of both rapidly and slowly moving trains.

With the foregoing considerations in mind, objects of the present invention are to provide a crossing protective system adapted to controlthe actuation of crossing signal devices in accordance with the speed of approach of vehicles to the crossing; to provide such a system embodying means to delaythe operation of the signaling devices upon the approach of slowly moving vehicles; to provide such a system constructed and arranged to provide a substantially uniform period of operation of the signaling devices in re- "eA'rENr OFFICE-f sponse to the approach of vehicles operating at a relatively wide range of speeds; to provide such a system involving a series of relays interconnected together and arranged to measure the speed of approach of a vehicle, and involving additional mechanism responsive to the timing relays for actuating the signaling devices at the expiration of a period determined by the timing relays; to provide such a system embodying means to insure timely operation of the signaling devices even in the event of failure of the timing mechanism; to provide such a system constructed and arranged to insure proper operation in the event a following train approachesthe signal at a time that a leading train is within the signaling zone; and to provide such a system, in which the same timing mechanism may be used for vehicles 'appreaching the crossing from either direction.

With the above and other, as well as more. specific objects in view, which appear in the following description and in the appended claims, preferred but illustrative embodiments of the present invention are shown in the accompanying drawings, throughout the three views of which corresponding reference characters are'us'ed to designate corresponding parts, and in which:

Figure 1 is a diagrammatic View of the improved crossing protective system as embodied in a rail-highway crossing; 4

Fig. 2 is a diagrammatic View of a modification of the systems shown in Fig. 1; and,

Fig. 3 is a diagrammatic view of a further feature of the invention which may be embodied in the systems of Fig. 1 and Fig. 2.

Referring particularly to Fig. 1, an illustrative highway His illustrated as intersecting a rail system having the two rails TI and T2; signaling devices comprising thewarning lights LI and L2 are positioned adjacent the crossing and at opposite sides of the-track, in positions to warn highway traffic of the approach of trains on the tracks TI and T2.

bc, extending in one direction from thecrossing. For purposes of description, the section a-b may be termed an operating or warning Illustrative 10 As stated hereinbefore,

the signaling devices LI and L2 are to be regarded section, and the section b-c may be termed a timing section.

The illustrated relay mechanism comprises a series of three relays IR, 2B,, and 3R; a series of conventional track system, but are shown as connected thereinto in accordance with the so-called continuous system. For this purpose, section b c is provided with a batteryBI, connected between the two rails TI and T2, andthe terminals of the relay IR are also connected to the two rails TI and'Tg; Similarly, section ab is provided with a battery B2 connected between the two rails and the relay 3R is, also connected 5 between the two rails. 1' a .are connect'edtogether asa relay chain and function infresponse to the de-energization of the relays IR'and 2R, to measure the time re- The timing relays ITQZT, 3T, 4T, 5T, and 6T quired by a vehicle'ito traverse the timing seccessive' de-energizing-of the timing relays and Thenumber of timingrelays ole-enerthetiming section thus servesas 'a measure of thespeed of. the'vehicle;

The details of connection offlthe timi ng relays canbest be understood from the description of operation given below; Itis noted at this time,

.however, that each of the timing relays IT, 2T,

3T, 4T, ET and 6Tis provided with a seriesof front contacts and a; series of back contacts, the front contacts being closed when the associated coilis energized and the back contact being closed when the associated coil is tie-energized.

Each of the'timing relays is provided with. timing mechanism to delay the movement of the armature from theenergized to the ole-energized or released position for a predetennined period, 9.1-

' though the closing movements arenot delayed, and the contact" arrangement; in each relay is such that the front contactsreach the openpositionsislightly before the back contacts reach the closed positions. The timing'mechanismis' diagrammatically; indicated by the' blacked'in portion of eachjrelaycoil, and in practice may be arrangedin anyof a variety of well-known sways The auxiliary relays IaT, *iaT, 3aLT,

KAaJI', 5q.T,"and 6aT respond to the timing relays 1 of corresponding 3 number and are provided with 'time jdelay mechanisms to" give them progressiveflyi ncreasing periodsof delay. That is, the time delay forjrelay IaTis of minimum value, and

the time delay periodsprovided for. relays ZaT,

, etc. are of' progressively increasing duration.

iThe number of timingzrelays IT, etc; which fare. de-energized' as above described determines .Which of. the auxiliary timingrelays are deene z d-1 and, .eoc nu eflr dete min h As'described-in more detail herein. rafter, -de-energization ;of the relays IF, and ZR. .results in" the timing relays IT, etc. being successively de-en'ergized; The'de-energization of .the relay 3R; 'which.occurs ,when the vehicle --enters. the warning. section interrupts this suclength of the interval by which the operation of the signaling device is delayed after the entrance of the vehicleinto the warning section a-b.

The circuit connections of the auxiliary time" in the positions occupiedwhen the coils are enerfgized; in which cases, all of the relay front contacts are in the closed position, and all of the relayxback contacts are in the open position.

These are the positions occupied by the relays as long. as neither of the sections b-.c and a-b are occupied by a vehicle effective to cause operation of the signal. devices.

Throughout the following description only those relay contacts are mentioned which have an effect-uponthesequence being described, in 'order tov simplify the description. 1

Sequence: of ,opemtion- -Rapz'dly moving trains Assuming, for example, that a train moving at orabove the maximum'rate of speed for which the control system is set; that is, a train for which .themaximum zsignal distance is desired, approaches the crossing from the right as viewed in Fig. 'l,. the entry thereof into section bc forms a short circuit between the rails, which acts to divert current away from the coil of the relay IR.'1'Accor.dingly, relay IR falls to a de- .energizedp'osition, and the opening of its contact Relay 2B. in turn falls to the'de-energized position immediately, notime delay mechanism being' providedbn this relay; and in so doing opens the contact ZRI, The opening of contact 2R! interruptsthe circuit for the coil of the first time relay IT, which circuit initially extends fromthe positive line through the contact SR I, contact ZRI, and through the 'negativeline. 7

'Dpon'interruption ofqthis circuit, the arma- {t'iirepf relay IT tends tofall'to the de-energized position, which action -is, however, delayed by the mechanism associated therewith. LUntil this time delay mechanism times out, accordingly, the front contacts of relay IT remain 'closed and the back contacts thereof remain "on ni :entire sectionZr-c. In the instance being decoil ofi relay IT tothe scribed, accordingly, the vehicle, enters the section a-b*'before, relayJT times out. The entry ,of. the vehicle into section a-"b completes a shunt f'circuit arouridyand lie-energizes, the remaining :relayj3R., In response to" this action, relay 3R falls to-the dc-energized position, bringing its jmovablejcontact 3RI into engagement with an associated lower contact, and also opening its jcontacts j3R9 and ,3RIO. The action of contact 3RI-completes a reenergizi'ng circuit for the coil ,of the time relay IT, which extendsfrom the positive line through contact '3RI, thestill closedmfront contact ITI,

,and thence through the 'coil IT to the negative side of the linel As long,'accordingly, as contact :.3R I remains clos'ed,.or, in other words, as long Ias ,the vehicle remains within the section b'-c ,a continuous energizingeircuit is provided for th se? tesw lia an t as we a the other time relays, all remain in the energized position. The entrance of the vehicle into the operating section thus interrupts the previously instituted timing action- The opening of contacts 3R9 and 3R! inter:- rupts both of two initial energizing circuits for the coil. of the signal relay XR. One of these circuits includes the contacts of the auxiliary time relays in series, but these contacts are now closed as stated.

The interruption of the circuits for the signal relay XR, causes the contacts XRZ thereof to close. Closure of the contact XR2 completes cir- .cuits for each of the signal devices LI and L2 located at the crossing, which circuits extend from the positive line through the contact XRZ and thence in parallel through the signal devices LI and L2 to the negative lines.

As the trailing end of the vehicle passes out of section b-c, the relay IR is again energized and closes its contact IRI, re-completingthe original energizing circuit for the coil of the relay 2R. Relay 2B in turn resumes the energized position, reclosing its contact ZRl. Closure of contact 2R! has no effect other than to prepare the original energizing circuit for the time relay IT. The passage of the vehicle out of the timing section accordingly has no effect upon the actuated condition of the signals.

As the trailing end of the vehicle passes beyond the rail joint a, the relay 3R resumes the energized condition, and the contacts thereof move to the original positions shown in Fig. 1. The reopening of contact 3R2 breaks the previously traced holding circuit for the time relay H, but this action is without efiect since the original circuit for the latter relay is now complete through contact ZZRI.

The reclosure of contacts 3R9 and 3Rlil recompletes the original energizing circuits for the coil of the signal relay XR, the contacts of which accordingly resume the positions illustrated in Fig. 1. The opening of contact XRZ interrupts the circuits for the signal devices LI and LZ,

terminating the signal operation.

Reviewing the just stated sequence, it is noted that the entrance of a train into the timing section b-c starts the timing mechanism in operation, and the departure thereof from the timing section terminates the operation of the timing mechanism. If the train is traveling at or above the maximum speed for which the system is set, the interruption of the timing action occurs before any of the timing relays become deenergized,

I; and, therefore, the signals are placed in operation immediately upon the trains entrance into the operating or signal section ab.

Sequence of operationSZowZy mooingtmins By the term slowly moving train reference is herein made to a train moving at such a rate that the time required to traverse the timing section bc exceeds the time required for one or more of the time relays iT, 2T, etc. to time out. The timing out of these time relays, in turn, through the auxiliary time relays laT, etc., delays the actuation of the signal devices LI and L2 for a period determined in accordance with the number of the time relays which time out.

Considering the case in which the speed of the train allows only one of the time relays, that is, time relay IT, to time out, it will be appreciated that, as in the previous example, the entrance of the vehicle into the timing section b-c deenergizes the relays IR and 2R, which in turn de-energize the coil of the first line'relay- IT, the circuits involved beng the same as those previously traced.

At the expiration of the period for which relay IT is set, the front contacts thereof. move to the open position, and the back contacts thereof move to the closed position. The opening of contact ITZ interrupts the circuit for the coil of the second time relay 2T, causing this relay to start timing out. .The opening of the contact IT3 interrupts one of two energizing circuits for the coil of the first auxiliary time relay IAT. The other energizing circuit for relay IAT is controlled by contact 3R1.

When the vehicle enters the section (1-4); the relay 3R is de-energized, as previously described, and all of the contacts thereof move to the deenergized positions. In this instance, the opening of contacts 3R9 and 3RIU is without effect, since the contacts 1T5 are now closed in parallel therewith. Similarly, the closure of contact 3RI is without effect, since the contact ITI in series therewith is now open.

The opening of contact 3R! interrupts the remaining energizing circuit for the first auxiliary time relay IAT, which accordingly starts timing out. The closure of contact 3R2 completes a re-energizing circuit for the coil of the second time relay 2T, which circuit extends from the positive line through contact 3R2, contact 2TI, and thence through the coil 2T to the negative line. Completion of this circuit, as will be appreciated, interrupts the timing out of the second time relay 2T.

The de-energization of the coil of the auxiliary time relay IaT, effected by the opening of contact 3R1, described above, causes this relay to start timing out. At the expiration of the time period provided by relay M1, the contacts IaTI thereof move to the open position, interrupting the circuit for the signal relay XR which, as described in connection with the first example places the signal devices Li and L2 in operation. In this instance also, closure of contact XRI upon its lower stationary contact provides a re energizing circuit for time relay IT, which thereupon recloses and through contact ITS causes reclosure of relay IaT. The signal relay KR thus acts, upon operation, to reset all operated time relays and auxiliary time relays.

As the trailing end of the vehicle passes the rail joints 1), the relays PR. and 2B. are again energized and the contacts thereof resume the illustrated energized positions. Re-energization of relay 2R prepares the original energizing circuit for the first time relay IT, but does not affect the circuits for the signal devices.

As the trailing end of the vehicle passes out of the section aF-h, the relay 3B is re-energized and the contacts thereof resume the illustrated positions. The reclosure of the contacts 3R9 re-energizes the signal relay, as described in connection with the first example, restoring the signal devices LI and L2 to the inactive condition. Movement of the contact BRI of the relay 33 into engagement with its associated upper stationary contact recompletes the original energizing circuit for the coil of the timing relay iT.

Summarizing the just described example, it is noted that the timing out of the time relay iT before the vehicle passes entirely through the timing block b-.c renders one of the auxiliary time relays, in this case IaT, eifectiveto delay the operation of the signal for a predetermined period after the passage of the vehicle into the operating section, a-'-b. In accordance'with'th'e present invention, the period of delay afforded by the auxiliary time relay IaT is such thatlthe signals remain actuate'din response to the 'just described slowly'm oving train for a period' which does not differ, more than a predetermined amount, from the period during which theywould be actuated by a train traveling at the maximum speed for which the system is designed. v

Considering the case of, a train 'traveling'at a 'still lower rate, sufiicient to allow, during its passage through the section b-c, time relay 2T, as Well as time relay IT, 'to'time out, it is believed 'to be evident that, as in the preceding example, the timing out of relay IT de-energizes the coil of relay 2T, and also renders the circuit forthe coil of the auxiliaryjtime relay IaT subject'to contacts 3R1 of relay 3R.

Upon the timing out of the relay 2T, the contacts thereof fall to the de-energized position. The opening of contact 2T2 de-energiz'es the third time relay 3T and starts its timing out laction. The opening of contact 2T3 renders/the circuit for the coil of the second auxiliary time relay 2aT subject to contacts 3R'I,"and the closure of contact 2T5 completes a circuit to battery around the contacts ERIU, ITS, and IaTI, but iswithout other immediate effect. v

If" the train passes the rail joints 1) before the time relay 3Ttimes out, which timing out action vbeganwith the timingout of relay 2T, as just described, it is believed to be evident that the consequent closure of the relay contact 3R3 com,- pletes a re-energizing circuit for the coil of the time relay 3T and interrupts the timing out there-,

of. In this event, the only time relays involved .in the operating sequence are relays 'I T and ET and the auxiliary relays IaT and MT, both of which are de-energizedand start timing out when the vehicle enters section a1'b and de-energizes relay 3R. In this case the signal devices are placed in operation when the time relay, ZaT times out, opening the contacts 2aT I. This action opens the only available energizing circuit 'for the coil'of the signal relay XR, it being noted that the time, delay of relay IaT is shorter than the time delay of relay 2aT,'so,tha't thecontact I aTI opens prior to the opening of contact ZaTI, but without effect. The de-energization of the coil of relay XR places the signals in operation in accordance with the previous description, and

7 also resets time relay IT. Timerelay IT in-turh resets relays 2T and IaT; and relay 2T resets relay 2aT. I

As the trailing end of the vehicle passes beyond the rail joints b, relays IR. and 2R are re-energized, but the system remains otherwise unaffected.

As the trailing end of the vehicle passesbeyorid the rail joints a, the operating relay 3R is reenergized and moves the contacts thereof to the illustrated positions. Reclosure'of contacts 3R9 re-energizes the signal relay XR, terminating the signal operation.

It is believed to be evident that in the event the vehicle moves at a lower rate than considered in the "immediately preceding examples, some or all of the remaining time relays 3T, 4T, ST, and BT may time out during the .passage of the vehicle through the timing section b -c, in addition to the relays IT and 2T. It is believed to be evident also that as each succeeding time'relay 3T, etc. times out, it opens the circuit to the coil of the succeeding time relay, initiating .the timing out thereof. Also, as each time relay times out, it

renders the' circuit of the associated auxiliary time relay subject to the contact 3R7, which; in

turn, initiates the timing out thereof upon the entrance of the vehicle into section a-b.

1 The circuit for the coil of relay XR is ultimately controlled by the contacts of the last of the auxiliary time relays to be de-energized. mAssuming the time relay 4T is'the'last one to completely time out during the passage of the vehicle through the timing section, closure of the contacts 4T5'thereof forms a shunt circuit around all of the contacts 3RIO, IT5, IaTI, 2T5, ZaTI,

3T5, andl3aTI. The opening of the contacts IaTI, 2aTI, 3aTI, therefore, which occurs prior to the opening of the contacts 4aTI because the time delay periods thereof are progressively shorter, doesnot interrupt the circuit for the coil of relay XR. At the expiration of the timing period for which relay 4aTI is set, however, the-opening of contacts 4aLTI interrupts the only existing circuit for the coil of relay XR, causing it to assume the de-e'nergized position and'plac'e the signal devices inoperation.

As'in the previously described examples also,

enters the warning section after time relay 4T of relay 5T, the de-energization of the relay 3R completes'a re-energizing circuit for the'coilof the time relay 5T through the contacts 3R5 and the still closed contacts 5TI; and tie-energizes all of relays IaT, 2aT, 3aT and MIT.

In each instance also where one or more of the time relays is timed out during the passage of the vehicle through the timing section, the deenergization of relay XR causes the resetting'of all operated timing relays; and the passage of the trailing end of the vehicle beyond the rail joints and immediately restores the relay 3R to the original position, which in turn re-energi'zes relay XR, terminating the signal operation. i

The actual calculation and determination of the timing of the various timing relay's IT, etc. and. the auxiliary time relays IaT, etc. may be determined in various ways, depending upon the operating requirements of the associated protective system,. and principally by the selection of the maximum and minimum periods of operation of the signal devices for the range of speeds at which trains may be expected to traverse the timing and warning section. For example, it may be desired to provide a minimum operating'period of 25 seconds for the signal device, and to provide a maximum operating period of 35 seconds therefor. The minimum signal period of 25 seconds, in conjunction with the maximum allowable speed of the trains on the system, of course immediately determines the length of the warning section,

stance, is required to impose-anadditional ten has timed out, but during the'timingout period seconds delay in the operation of the signal devices. Therefore, the initial auxiliary time relay laT requires a setting of ten seconds; relay 2aT requires a time setting of twenty seconds; relay 311T a setting of thirty seconds, etc., the last illustrated auxiliary time relay BaT requiring a time setting of sixty seconds. 4

The selection of the twenty-five seconds minimum and thirty-five seconds maximum operating times for the signal devices also determines the time intervals required for the timing relays IT, 2T, etc. That is to say, a train traveling at the maximum allowable speed must traverse the timing section 11-0 in a time just slightly less than the timing afforded by the time relay 1T,

since, as previously stated, for a train traveling at maximum speed, the signals are required to be placed in operation immediately upon the eratrance of the train into the warning section aP-b. Since the maximum warning period is thirty-five seconds, it follows that a train traveling slightly inexcess of of the maximum operating speed must also traverse the timing section before the timing relay 1T times out; and, a train traveling at or below ;;,-,'of the maximum speed must require a time to traverse the timing section which exceeds the time period for relay IT. The time period ior relay iT is, therefore, the length of the section Z270 divided by 2% of the maximum allowable speed.- Or, where: i

Z=length of section b-.-c; ti=timing period of relay lTI; m=maximum allowable train speed;

The value if] is given by the expression:

To go further, it is believed to be evident that the second time relay 2T would be allowed to time out in the event of the approach of a train traveling at a speed less than of the speed of a train which allows just the one relay .IT to time out. That is to say, the total time period (to) allowed by timing relays lT and 2T-is:

- accumulated time periods of the preceding relays in the series.

The total number of relays used determines the range of speeds below the selected maximum speed within which the signal operation'may be maintained within the selected limits. Conversely, the number of relays used determines,-for a particular range of speeds, the maximum and minimum periods of signal operation. For a given range of speeds, the-greater'the number of timing relays used, thecloser may be maintained the maximum and minimum signal operating periods. s I

it will be noted that all signaloperations, as affected by the time relays and theauxiliary-time relays, are initiated by the dropping out ori.de energization of these relays. The danger of a'ny of the time relays, or .other relays :in the..-systen fa'iling'to fall to the ide-ene'rgized position when the coil thereof is de-ie'nergized is negligible. It may occur from time to time, however, due to wire failure or other causes that a relay will falsely fall to the de-energized position or will fail to move to the energized position when the coil thereof is energized. In accordance with the present invention, means are provided to prevent a false operation of the signals in response to failures of the just stated character and also to assure that, in the event of such a failure a maximum period of signal operation is provided Referring further to Figure 1, the contact 3R9 is connected to supply a direct energizing circuit for the coilof the signal relay KB. A false opening of any-of the auxiliary time relay contacts :la'ii, etc., therefore, is-inefiectiveto de-energize circuit of which includes the contacts lT4, 2T4,

.etcrof the time relays in series. time relays remain in the energized position, 'relay K also remains energized. Also, upon move- 'ment to ,the energized position, the relay K completes a self-holdingcircuit for itself through its own contact Kl contacts 3R8 and 2R2 in parallel, and through the contact of-the signal relay me when the latter is in its upper position. Due

to the contact XR, this self-holding circuit is ebi-ok'en each time the signal relay XR operates. 15 at this-time anyof the time relays IT, etc. are inthe tie-energized position, relay K falls to the de-energized position, and can 'be re-energized .onlyhyireclosure of-all of the time relay contacts. 'Ifany time relays thereforfail to restore themselves after the train passes the crossing, the relay'K remainsin. de-energized position. On the other hand, if any of the time relays IT, 2T, etc. drop away when no train is on either track section, the control circuit for relay K is broken, and

As long as all.

since the self-holding circuit includes front con- 'ataGtSLQRZ and 33.8, which are open when the track sections are unoccupied, relay K drops out. iAta-ny time that relay K is in the de-energized position, the contact K2 thereof is in the open position, and renders the signal relay XR. subject Eto control entirely by the relay 3R at contact 3R9.

Although no abnormal movement of any time relay to de-energ-ized position results in a deenergization of the checking relay K, the normal operation of these relays to the de-energized position .does not have this effect, since, any time-a time relay is normally de-ene'rgized, oneor the other of the relays ZRor 3B is :also'de-energized .by the presence of. a vehicle in the associated section. .Wheneitherof these two relays is de.-

energized, the contacts :tRB .or 2R2 thereof, as

-thecase-may be,'closes inthe previously described self -ho1ding .circuit and retains the checking :re lay K in the ,energized position until the signal relay XR'is deenergized.

Checkingrelay K thus normally remains en "ergized, is .de-energized immediately upon the :false falling away of a time relay if no vehicles .are in the section, is automatically deenergized at i end of each operating sequence in which any ,one of the timesrelays isiproperly de-energized; is res-energized.only=.if.;all operated timerelays prop- 1. r ,-.In the ,event the leading train passesbeyond I erly. lreclose;. and,when de'-.energiz'ed,.renders'ithe 'signall de'vices subject entirelyto the relay 3Rn'. It may occur from time to time that during the .passageof onetrain through .the warningsection kt b, -.a following train will enter the section b c..wIn such instance, the illustrated arrangements reduceany delay which; inthe absence or theleading: train, would otherwise be introduced into the'operation'. of thesignals by. the. approach ofthe following train. I l o accomplish' thisthe-system is soiarranged that i'fithelsignals have been placed in operation bya leading train,and if, while such leadingtrain is still occupying the warning section and. thus maintaining.thLsignals in operation, a followingtrain enters the timing section, such. entrance of-la'ifollowing .trainis ineffective to initiate the -timing action.=-.-As previouslydescribed, the contactI-XRl...;of..the signalrelay XR, when in the lower position, closes an energizing circuit for the coil. of uthe first. time relay. .1 TL long. as 'thlS lel'leIglZlI1g'I circuit is complete, therefore,.=.the dee'nergization.of--.the relays. IR and 2R-which results from the entrance of the followingf...train into the timing. section is ineffective to. de-ene'n .gize the first 'timing-'relay:.lT.1; Since. timing .ree

. .lay IT. directly controlszthe3succeeding.timeureslays, such entrance is equally ineffective -.to cause the. de-energization.-.of any other time relays 1231, 3T,.etc.. 1;; .1 I...

zIfzthepassage of the leading trainbeyondthe .railjoints a occurs after the entrance of the 011- -lowing-train into the warning section,.no.inter.- ruptionin thesignal operation occurs during the passage ofthe two trains past the intersection, since in. this I instance relay 3R not re-ener- .gized'when' the. leading train passes beyond the :railjoints'a. Accordingly no re-energization of :the signal. relay XR occurs until the following .train has'passed beyond theintersectiom for relay IT. Relay 2R being now de-energized .by the presence of the following train in the tim- 3 ing.section, relay IT becomes de-energized and :55

initiates the usual timing action. In this case, .hgwever, since the timing is not initiated immeg diately upon the entrance of the following train into thetirning section, any time delay. which no'rmal traflic congestion. at thecrossing making i v,wquld normallybe occasioned by such following train is shortened and the maximum allowable jwarning period is provided for such train. This desirable since the passage of the leading train pastthe;intersection may have occasioned an ab- ;it advisable to give a substantial period of warnin ,ofnthe approach of the following train.

- Modified embodiment-Jig. 2

-. ;.Referring 'iowto Figure 2, an embodimentof the invention is shown in which the auxiliary ,time relays may be omitted, and the .function there'ofperformed-jby introducing selective delays zinthefi-relea'se of the signal relay XR. In the xembodiment of *Fig. 2,.each of the time relays,

insteadoi. starting the timing out of an auxiliary time relayga's' describedxwith reference'to Fig. 1, completes a-di'scharg'e'circuit for the .coil'of XR, the discharge circuit embodying one or more con densers, which causes a how of current through the coilof thesignal relay, which flow continues forithe predetermined time period; V The general arrangement andoperation of the system shown in Figure 2 duplicates that shown in Figure l. That is to say, the relays IR, 2R,

and 3B are provided in the same circuit relation to each other, to the signal relay, and to the respective sections; anda series of time relays I T, 2T, 3T, etc. is provided, the energizingand selfholding circuits of which are arranged as described in connection with Figure. 1.

So'fa-r asconcerns the operation of the system, accordingly, in the instance where a train is traveling at or above the maximum speed for which the systemnis adjusted, the operation duplicates that ofthe system in Fig. 1. The sequential dropping out of the time relays IT, 'ZT,

etc., in the event the vehicle traversing the timing section bc travels ata rate below the maximum; speed, is also thesame as .described with reference to the system in Fig. 1.-

, .In the arrangement of Fig. 2, the previously described contacts T4, 2T4, etc. of the respective time relays are connected in parallel branches of a circuit. leading to the signal relay XR. Each contact IT4, etc. is disposed'to be open when the associated coil is energized. Closure of each contact, however, connects .an' associated condenser IC, 20, 3C,"etc. in a local circuit'with the coil of the signal relay Each local. circuit extends from the negative side of the line, or the common return conductor, through an associated time relay contact and thence through the coil of the signal relay XR' to the negative or common return line.

,gized position,the contact3R9 affords a charging .circuit for'condenser IC.- Similarly,'upper fixed jcontacts associated .withthe moving contacts 3R2, 3R3, etc. provide corresponding charging.

circuits for the condensers 2C, 30, etc. As long as no vehicle occupies the warning section -ab, accordingly, all condensers are supplied with charging current and are thus normally in a charged condition. The capacities of the respective condensers are such that they provide time delays inthe dropping out of the signal relay XR which corresponds to the time delays provided by the auxiliary time relays of the systern of Figure l, V

view of the preceding-description of Fig. 1 and the immediately preceding description with A charging circuit for each condenser is provided by a contact on the relay 3R. For example, when relay 3R is in theenerreference to Fig.2, it is believed that a description of one typical operating sequence will serve,

-to;-make;the'operation of the system of Fig. 2 entirely clear. Assuming, for example, that a :vehicleenters the timing sectionb-c, the relays |R. ,and 2R, arede-energized ,as previously described, andthe de-energization ofthe lattersta-rtsthe timing out of thefirst time relay IT. If the vehicle enters the warning section 'a-b priorftorthetimin-g out of relay IT, the consequent-dropping out of the. relay 3R immediately de energizes the coil ofa-the signal-relay XR (at contact 3R8). Under these conditions no delay is introducedinto the dropping out of the signal relay and it immediately closes the contact XRI tokplace the signaldevices LI. and L2: in operation.

If 2 thexspee'd iof .ath. train is. below the just stated value, one or more of the time relays IT, 2T, 3T, etc. may complete their timing out before the vehicle enters the warning section ab. Assuming, for example, that time relays IT, 2T and 3T drop out, three parallel discharge circuits are provided for the coil of relay XR, one of which includes condenser IC, the second of which includes condenser 20 and the third of which includes the condenser 3C. The circuit including condenser 2C is in itself sufficient to afford a predetermined time interval corresponding for example to the time provided by the previously described auxiliary time relay MT. The additional discharge circuits connected in parallel with the first are effective to supplement the effect of the first, and provide a total time delay in the discharge action which equals the total time afforded by the auxiliary time relay 311T of Fig. l. The dropping out of the three time relays IT, 2T, and 3T in the order named and at the time intervals described with reference to Fig. 1, affords a discharge circuit for the coil of the signal relay XE, which delays its release movement for an interval equal to the interval provided by relay MT in the system of Figure 1.

Modified embodiment-Fig. 3

In each of the foregoing two embodiments, sections at only one side of a crossing have been considered. In the broader aspects of the invention, arrangements for effecting proper signal operation for trains approaching the crossing from either direction, and to prevent false signal operation by trains leaving the crossing, may be effected in various ways. A preferred arrangement, however, is shown in Fig. 3.

Referring to Fig. 3, the rails Ti and T2 of an illustrative track are intersected by a highway H, and are divided by rail joints a, b, cl, 02, d, and e, into two timing sections dr-b, and elf-e, disposed at opposite sides of the crossing; and two warning or signal sections 17-0! and c2-d also disposed at respectively opposite sides of the crossing. The two control relays 2R and 3R are arranged for selective control by vehicles approaching the crossing from either direction, and correspond in all respects in function to the cor espondingly numbered relays in the systems of Figs. 1 and 2. The various circuits controlled by the relays 2B and 3R are therefore not shown in Fig. 3, in order to simplify the drawing.

The control of the two relays 2R and 3R is effected by a series of three relays of the interlocking type, the coils of which are designated 6R through 9R. Relays 4B and 5B are mechanically connected together to form an interlocking relay structure, such, for example, as the type disclosed in the Patent No. 1,799,629 granted to Lockhart April '7, 1931; that is to say, the armatures of these two relays are connected to-, gether in such a waythat if one of them is deenergized and falls to the de-energized position, it mechanically locks the other against movement beyond a mid-position, part way between the energized and the de-energized position, and the interlocking thus interposed is not released until both relays are restored to the energized condition. The relay GR is connected directly across the timing section a-b, and normally is energized from a battery B3. Contact 43! of relay 4B is of the so-called flagman type, that is, it is closed when the associated coil is energized and moves to the open position only if the associated relay is permitted to fall to the completely tie-energized position. 'The relay SR is used simply to interlock the relay 4B and the coil thereof is connected in a local circuit including a contact 6R2 of the relay GB. The contact 6R2 is not of the flagman type, and is closed only when the associated coil SR is energized.

The two relays $R and IR, are connected respectively across the sections b-cl, c2 and (1-01, 02, and normally receive power from batteries B4 and B5. The relays BR and IR are interlocked together in the manner described with reference to relays 4B. and ER. In addition to the previously mentioned contact 6R2, the relay GR is provided with a contact 6R3 of the flagman type. The relay IR, is provided with contacts IE2 and IE3 which duplicate the corresponding contacts of relay 6R. Contacts 6R3 and IE3 are disposed in series in a circuit which includes the coil of the relay 3B. In addition, relays ER and IR are provided with back contacts GRI and ER! to form a conventional staggered connection of relays BR and IR into the sections b-cl, c2 and d-cl, 02.

The remaining two relays 8B and 9B are related in the manner described with reference to relays 4R and ER. The relay 8B is controlled by the contact IE2 and the relay SR is provided with a contact QRI of the flagman type which,

in conjunction with the previously described con-- tact ARI, controls the circuit of the relay 2R.

A typical operating sequence is as follows:

Assuming that a vehicle enters the approach section a-b, the relay 4R is de-energized and the contact 4R6 thereof moves to the open position, interrupting the circuit to the relay 2R with functions as described in connection with Figs. 1 and 2. The de-energization of relay 4R also mechanically locks the armature of the relay 5R but this is of no consequence in the present instance since no contacts of relay 5B are utilized.

As the vehicle proceeds through the timing section ab and enters the warning section bcl, 02, the relay ER is tie-energized and falls to the de-energized position, opening the contacts 6R2 and 6R3. The opening of contact 6R3 de-energizes the relay 3?, which functions as described in connection with Figs. 1 and 2. The opening of contact 5R2 ole-energizes the coil of the relay 5B which operation is without effect in the example being considered. The de-energizatio'n of relay 6R also applies a mechanical interlock tothe armature of the relay IR. The passage of the leading end of the vehicle past the rail joint cl is without immediate effect upon either of relays GR. and IR. The passage of the leading end of the vehicle past the rail joint 02, however, completes a direct shunting circuit for the coil of relay ER. Upon being tie-energized, relay 1R, closes its contact IRE and opens its contactlRZ. Contact 1R3, being of the fiagman type as previously described, is retained closed by themechanical interlock previously applied by relay 5R. The closure of contact 'Z'Bi is without effect during vehicle travel in the direction now being described, but the opening of contact 132 de-energizes the coil of the interlocking relay 8B.

As the trailing end of the vehicle passes out of the section a-b, the relay 4B is re-energized and recloses its contact 4R1, recompleting the circuit for the relay 2B. This relay, accordingly, resumes the energized position which, as described with reference to Figs. 1 and 2, is without eiiect upon the signal devices located at the intersection.

When the trailing end of the vehicle passes the rail joint cl, the initial direct shunting circuit until-the trailing end of-thevehicle passes the rail joint C2, atjwhichtime the just described supplemental shunting circuit is interrupted, re-

storing the coil 6R. to the energized condition.

The re-energization of relay 5R restores all of the contacts thereof to the illustrated positions.

jes

Reclosure of contact 6R3 re-completes the energizing circuit forthe relay 3R which, as described with reference to Figs. 1 and 2, restores the signal system to its original unactuated condition. The reclosure of contact 6R2 re-energizes the coil of the relay 5B, which thereupon resumes the energized positionreleasing the interlock between relays 4R and ER. Reopening of contact GR] is without effect. 3 V i As previously stated, the reenergization of the relay 6R does not release'the mechanical interlock previously applied thereby to the armature of the relay TR. Accordingly, relay 1R remains in the interlocked position until the trailing end of the vehicle passes beyond the rail joints d. At this time, the relay 1R recloses its contact 1R2, re-energizing the relay BR, and reopens its contact IRI. The latter action is without eifect.

The re-energization of relay 8R does not release the, previously applied interlock t0 the armature relay 9R, but as the trailing end of the vehicle passes beyond the section de, coil 9B. is reenergized and'releases the lock. No change in the position of the contact 9R! occurs, however.

From the foregoing description, it is seen that the passage past the intersection of the vehicle traveling in the direction stated; first de-energizesthe relay 2R, upon the entrance of thevehicle intothe approach timing section; and deenergizes the relay 3R upon the entrance of the vehicle into the approach operating section. Relays 2 Rand 3R remain de-energized until the trailing end of the Vehicle passes beyond the rail joint 02 at the far side of the intersection. The re-energization of relays 3R and 2R, which occurs when the trailing end of the vehicle passes the rail joint 02, restores the signal system to its original unactuated condition. During the passage of the vehicle through the operating and timing sectionscl, c2-cZ andde, the mechanical interlocks applied to relay TRby relay GR and applied to relay 9R by relay 8R remain effective. No signal operation accordingly results from the passage of the vehicle through the just identified sections. When, however, the trailing end of the vehicle passes beyond the rail joint d, relay 'iRis re-energized, restoring itself to its original condition and releasing the lock applied thereto. Similarly, when the trailing end of the vehicle passes beyond the joints e, relay SR is re-energized and releases the lock previously applied thereto. I

It is believed to be evident thatv in the event of vehicle travel in the reverse direction, a signal timing action is'initiated by the entrance oi. the vehicle into the section de, at which time the relay 2B is de-energized. Similarly, the passage of thevehicle past the rail joints d de-energizes the relay 3R to either immediately place the signal devices in operation or to initiate a sequence which, places theisignaldevices'in operation after a suitable time delay, as'described with reference to Figures 1 and 2. Also, relays 2R and 3l't remain energized until the trailing end, of the'vehicle passes the rail joint 0!, at, which time the signal system is restored to its initial condition. Also, the relays GR, and 4R re-. main in the interlocked condition until the trailing end of the vehicle passes beyond therail' joints 2) and a, respectively.' The-interlocking relation of the system is such, accordingly, that only the-relays associated with the approach sections are efiective to control the signal relays ZR and 3R, and the relays associated with the outgoing sections are ineiTective to control relays 2R and 3R. 7

Although specific embodiments of the present; invention have been described and explained, it

will be appreciated that various changes in the form, number andarrangement of parts may be made in the illustrated arrangement within the spirit and scope of the present invention.

What is claimed is:

1. In a system for protecting a predetermined point along a traveled way, a protective device associated with said point, means defining first and second protective sections along said way in advance of said point, 'a-series of time element relays, means including circuit connections for normally maintainingsaid relays in an energized condition, means actuated by the passage of a vehicle through one of said sections forinterrupting the circuit connections for said relays to thereby deenergize said relays, and additional time element means controlled in accordance with the number of said relays which drop away and rendered effective upon-the entrance of a vehicle into the other of said sections for actuating said protective device atthe expiration of a predetermined interval-after said entrance;

2. In a system for protecting a predetermined point along a traveled way, a protective device associated with said point, means defining first and second protective sections along said way in advance of said point, a series of time element relays, a first normally completecircuit for energizing a'first one of. said relays, a secondnormally energized circuit controlle'd by said first one of said. relays for normally energizing a second one of said relays, means actuatedby the entrance of a vehicle into one of saidsections for interruptingsaid first circuit toinitiate a successive dropping away of said relays, and additional time element means controlled in accordance with the number of said relays which drop away and rendered effective upon the entrance of a vehicle into the other of said sections for actuating said protective device at the expiration of a predetermined interval after said entrance into said other section. e

3. In. a system for protecting a predetermined 1 point along a traveled way, a protective device associated with said point, means defining first and second protective sections along said way in advance of said point, a series of time element relays, means for normally energizing said reseries to therebysinitiate a successive dropping away'of said relays, means responsive to the entrance of said vehicle intothe other-of said sections for completing secondary energizing cirr ts t tal of a e ays wh h, have ress aw u n h P ssa e of said hi le h mi h s n sesi q and sen -sqn llsd in accordance with the number of said relays which dropaway for actuating said protective deyice. l A- n. a r r ir tt v a p ed t rmined. p 'atalq a e wa a o e ive dai ies as o ia with. s 'point mea s. definin firs and second protective sections along saidway in advance of-gsaid point, a series of time element relays, means for normally energizing said relay s including means whereby the dropping away of each relay interrupts the circuit for and decnergizes the next succeeding relay in the series, means responsive to the entrance of a vehicle into one of said sections for interrupting the circuit for and de-energizing the first relay in said series to thereby initiate a successive dropping away of said relays, means responsive to the entrance of said vehicle into the other of said sections for completing secondary energizing circuits for any of said relays which have not dropped away during the passage of said vehicle through said one section, and means also rendered effective by the entrance of said vehicle into said other section and controlled in accordance with the number of said relays which drop away for actuating said protective device.

5. In a system for protecting a predetermined point along a traveled way, a protective device associated with said point, means defining first and second protective sections along said way in advance of said point, a series of time element relays, means for normally energizing said relays including means whereby the dropping away of each relay interrupts the circuit for and deenergizes the next succeeding relay in the series, means responsive to the entrance of a vehicle into one of said sections for interrupting the circuit for and de-energizing the first relay in said series to thereby initiate a successive dropping away of said relays, means responsive to the entrance of said vehicle into the other of said sections for completing secondary energizing circuits for any of said relays which have not dropped away during the passage of said vehicle through said one section, a second series of time element relays corresponding to the relays of said first series, means forming a normally complete energizing circuit for each relay of said second series disposed to be interrupted by the dropping away of the corresponding relay of the first series, and means controlled by the number of relays of said second series which drop away for controlling said protective device.

6. In a system for protecting a predetermined point along a traveled way, a protective device associated with said point, means defining first and second protective sections along said way in advance of said point, a series of time element relays, means for normally energizing said relays including means whereby the dropping away of each relay interrupts the circuit for and de-energizes the next succeeding relay in the series, means responsive to the entrance of a vehicle into one of said sections for interrupting the circuit for and deenergizing the first relay in said series to thereby initiate a successive dropping away of said relays, means responsive to the entrance of said vehicle into the other of said sections for completing secondary energizing circuits for any of said relays which have not dropped away during the passage of said vehicle through said one section, a second series of time element relays corresponding to the relays of said first series, means forming anorfn'ally comp ete energizingv circuit for each relay o'f -.Zsaid v second series disposed to be interrupted by thedropping away of the correspondingrelay of the firstfse ries, and means also rendered efiective by the entrance of a vehicle'into the other of saidsections and controlled in accordance with' the number of. relays of said second series which dropfaway for. actuating said protective device.

In a system for protecting a predetermined point along a. traveled way, a; protective device associated with'sa'id point, nieans defining a tim ing section and protective section in advance of said point, a series of time element relays, means including circuit connections for normally maintaining said relays in an energized condition, means actuated by the passage of a vehicle through said-timing section for causing a successive interruption of the circuit connections for said relays to thereby de-energize said relays, means actuated by the entrance of a vehicle into said protective section and disposed upon actuation to actuate said protective device, and means controlled by said relays for delaying the actuation of the protective device after said entrance for a predetermined period determined by the number ofsaid relays which drop away.

8. In a system for protecting a predetermined point along a traveled way, a protective device associated with said point, means defining a timing section and a protective section in advance of said point, a series of time element relays, a first normally complete circuit for energizing a first one of said relays, a second normally energized circuit controlled by said first one of said relays for normally energizing a second one of said relays,

means actuated by the entrance of a vehicle into said timing section for interrupting said first circuit to initiate a successive dropping away of said relays, means actuated bythe entrance of a vehicle into said protective section and disposed upon actuation to actuate said protective device, and means controlled by said relays for delaying the actuation of the protective device after said entrance into said protective section'for a period determined by the number of said relays which drop away.

9. In a system for protecting a predetermined point along a traveled way, a protective device associated with said point, means defining first and second protective sections along said way in advance of said point, a series of time element relays, means for normally energizing said relays including means whereby the dropping away of each relay interrupts the circuit for and de-energizes the next succeeding relay in the series, means responsive to the entrance of a vehicle into one of said sections for interrupting the oncuit for and de-energizing the first relay in said series to thereby initiate a successive dropping away of said relays, means responsive to the entrance of said vehicle into the other of said sections for completing secondary energizing circuits for any of said relays which have not dropped away during the passage of said vehicle through said one section, a second series of time element relays corresponding to the relays of said first series, circuit connections for each relay of said second series disposed to be interrupted by the entranceof said vehicle into said other section providing the corresponding relay of said first series has dropped away, and means controlled by the number of relays of said second series'which dropaway for controlling saidpro tective device. v g

'10. In a system for protecting a predetermined point along a traveled way, a protective device associated with said point, 'means defining first and'second protective section's along said'wayin advance of said pointga' time element relay, means including circuit connections for normally retaining said relay inenergized condition, means actuated by the entrance of a vehicle into'one off said sections for interrupting said circuit connections to thereby de-e'nergi'ze said relay, addi-

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