US2880308A - Railway switch control apparatus - Google Patents

Description

March 31, 1959 2,880,308

SIH HSUIN TSIANG RAILWAY swITc CONTROL APPARATUS Filed Jui y 29, 1953 3 SheetsSheet 1 Fig.

INVENTOR. Sill Hsuzn Tsiany BY w.\..w

HIS A TTORYE'Y March 31, 1959 SIH Hsum TSIANG RAILWAY SWITCH CONTROL APPARATUS I 3Sheets-Sheet 2 Filed July 29, 1955 1NVEN TOR. Sill Hs'um Tsi any HIS ATTORNEY March 31', 195.9 -SIH HSUIN TSIANG RAILWAY swmcn CONTROL APPARATUS 5 Sheets-Sheet 3 Filed July 29, 1955 INVENTOR. Sill Hszzm Ts-z'any BY HIS ATTORNEY United States Patent RAILWAYSWITCH'CONTROL APPARATUS Sih..Hs'uih Tsiang, Pittsburgh, Pa., assignor to -westing house Air Brake, Company,, Wi lmerding, P n, a corps ration' of Pennsylvania Application Julyc29, 1953,.SerialNo. 370,941.

4 Cl aiins. (Cl; 246,-16 1.)

My invention. relates to apparatus for controlling rail: Way. switches, and: in particular to. apparatus for controlling railway switches in. classification yards;

In classification yards, railwaycars are sorted onto a number. of classification or storage tracks according to thedestination ofthe cargo in the cars: Ordinarily, a train. is broughtinto the classification yardand-individual cars or cutsof carsare cut loose atthe topof an incline usually referred to as the hump. These cars orcutsare accelerated by the. hump. and move onto the selected storage track correspondingto the cars ultimatedestination. In order toroutethe car or cutontotlieselected storagetrack, the. car. or cut. must pass over a plurality of railway. switches which may be'automaticallyor manually controlled. As .the caror cut'approaches each-switch, it enters; a detector. track. circuit which when occupied controls circuits: for preventing the associated switch from beingthrownuntil the caryhas cleared the switch, therebypreventingpossibl'e derailment. In the past, it has beenzcustomary to makethe detector-track circuitfapproxi mately-fifty-fivereet long. This necessitated spacing ears at a distance of'at.least fifty-five feet. However, with improvements; in automatic switching in classification yards, theghumping capacity of the yard can be increased by decreasing thelength of. the detector track circuits to thus effect a. decrease. in the required. spacing between cars or cuts.

When the spacing between cars is reduced appreciably, the danger of-a fast movingcar catching up with and running into; apreceding slow; moving car isgreatly. increased. Furthermore,.with cars going to; different classification tracks, it is. possible: that. after a slow moving car, has moved out of thedetector: circuit associated with a switch, the switch; may be: thrown. and a, fast; moving following car upon moving into the; adjacenttrack. may collide with the. first car so; that. aportion of the following fast moving car, usually: a. front: corner; will move against some portion, usually; a: rear corner,-.of theslower preceding car. Such a. collision. is known as; cornering, and is obviously; undesirable.

Accordingly, itis an object of my -invention, to; provide control apparatus whichwill prevent corne r ing.

Another object of my invention is, to provide apparatus which will delay the operation of a switch for a time;v if a vehicl approaches the switch at a speed below: a predetermined value, but which will permit; the operation of the switch immediately upon a vehicle clearing the switch points if the vehicle is exceeding the predetermined speed.

It is a further object of my invention to provide apparatus for controlling a. switch movement, which apparas Ills will measure the speed of a caror cut as it approaches the associated switch and will thereafter prevent the throwing of the switch for a predetermined time if the speed of the car or cut is below a given speed.

Yet an th r object o my n en ion. s to. p ovid anparatus for controlling a switch movement which. apparatus; will measure thev speed. of a. car approaching the ice 2. associated switch and will provide atime delay in the subsequent throwing of the switch after the car haspassed over the switch, which time delay will be inversely proportional to the speed of'the car.

According to my invention, I provide arailway switch for diverting traflic approaching the switch onto one of two tracks. I further provide means for measuring the speed of a vehicle approaching the switch and if the speed'is below a predetermined value, a means is actuated for delaying the operation of the switch for a suificient time to permit the slow moving vehicle to clear the fouling point of the switch. In this manner, it a slow moving vehicle moves over the switch onto one track, a second vehicle cannot immediately move over the switch onto the other adjacent track to thereby create the possibility of cornering.

Other objects of my invention will become clear hereinafter as the characteristic features of construction and mode of operation of my invention are described in detail.

In the. accompanying drawings, Fig. 1 is a diagrammatic viewshowing one form of railway switch control apparatus embodying my invention.

Fig. 2 is a diagrammatic view showing another form of railway switch control apparatus embodying my invention.

Fig. 3 is a diagrammatic view showing a third form of. switch control apparatus embodying my invention.

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

Referring first to Fig. l, the reference characters 1 and 2. designate the track rails of a. stretch of railway track which is connected by a switch W to two adjacent tracks T1 and T2. The track rails 1 and 2 are provided at points I and II with insulated joints 3 to. provide an insulated detector track section I-II. The insulated joints 3 at point II should be immediately in approach to the switch, that is, they should be located as close to the tips of the switch points of switch W as is possible and in no case should they be located from the tips more than the shortest distance between the wheels of trucks of vehicles using the switch. An insulated joint 3a is provided in rail 2 in section I.II to. divide that section into two sub-sections AT, hereafter referred to as a measuring section, and ET. A resistor Z is connected around joint 34: to provide an electrical path around that insulated joint.

Detector section III is provided with a detector track circuit which may be traced from they positive terminal of a track battery TB, over rail 2 from point I to joint 3a, resistor Z, rail 2 from joint 3a to point II, thewinding of a first track relay ATR, and rail 1- from points II to I to the negative terminal of battery TB. Sub-section BT is provided with an auxiliary track circuit which may be traced from the positive terminal of battery TB, over rail 2, the winding of a second track relay BTR, and rail 1 to the negative terminal of battery TB.

Also associated with sub-section ET is an intrusion detector including a source of light PL disposed on one side of the section, and a light responsive unit PC disposed on the other side of the section. The light responsive unit PC cooperates With an intrusion detection relay ZR so that when light is received by unit PC from lamp PL, relay ZR will be energized. A repeater relay TZPR is controlled by relays ATP. and ER and two time element relays lTER and ZTER. Relay TZPR in turn partially controls two control relays IWLR and ZWLR. Relays TZPR and IWLR together control the operation of the time element relays ITER and ZTER. Time element relays lTER and ZTER are provided with a normally closed checking contact a which opens immediately upon the. time element relay becoming energized and a normally open front contact b which closes after the relay is energized for a predetermined time interval. Switch W is controlled by a switch movement WM which in turn is is governed by two valve magnets RM and NM. The switch movementmechanism and the operation of the valve magnets form no part of my invention and it will suffice to say for the purpose of understanding the present invention that switch movement WM will operate soas to move the switch to its normal position inwhich cars will move onto track T1 when and only when valve magnet NM is energized and switch movement WM will operate switch W to its reverse position in which cars will move onto track T2 when and only when valve magnet RM is energized. Valve magnets RM and NM are partially controlled by a lever K, here shown as directly connected to the energizing circuits for the valve magnets. It will be clear that some remote control type of circuit controller can be substituted for lever K.

Except for the energy supplied by battery TB to relays BTR and ATR, the energy for the various portions of my novel apparatus is supplied by a battery LB having a positive terminal B and a negative terminal N.

As shown in Fig. 1, the apparatus is in the condition it assumes when the stretch of track is unoccupied and switch W is in its normal position. Relays ATR and BTR are energized by battery TB in the manner already described and are picked up. Since there is nothing to interrupt the .light beam being emitted by lamp PL, light responsive unit PC will supply energy to relay ZR which will be picked up. Relay 1WLR is energized by a first stick circuit which may be traced from positive terminal B of battery LB, over front contact b of relay ATR, front contact a of relay BTR, front contact b of relay 1WLR, and the winding of relay 1WLR to negative terminal N of battery LB. With relay 1WLR stuck up, relay ZWLR is energized over a first stick circuit which may be traced from the positive terminal B of battery LB, over front'contact a of relay IWLR, front contact a of relay ZWLR, and the winding of relay ZWLR to negative terminal N of battery LB. With relays IWLR and ZWLR both stuck up, relays lTER and ZTER will be deenergized due to the fact that their energizing circuits, which circuits will be subsequently traced, are both open. With time element relays 1TER and ZTER released, their checking contacts a will be closed and, accordingly, an energizing circuit for relay TZPR will be established, which circuit may be traced from positive terminal B of battery LB, over front contact a of relay ATR, checking contact a of relay 2TER, checking contact a of relay lTER, front contact a of relay ZR, and the winding of relay TZPR to negative terminal N of battery LB. With relay TZPR picked up, its stick circuit will be closed, which circuit maybe traced from positive terminal B of battery LB, over front contact a of relay ATR, front contact a of relay TZPR, and the winding of relay TZPR to negative terminal N of battery LB. With relays TZPR and IWLR both energized and lever K in its left-hand or L position, an energizing circuit for valve magnet NM will be established, which circuit may be traced from positive terminal B of battery LB, over front contact e of relay TZPR, front contact d of relay IWLR, the contact closed by lever K in its L position, and the winding of magnet NM to negative terminal N of battery LB. Accordingly, switch movement WM will be in its normal position as heretofore described. With switch movement WM in its normal position, switch W will be in the position shown in which any vehicle moving through section III in the direction indicated by the arrow will move onto track T1 and not onto track T2.

Let it be assumed that the entire detector track section 1-11 is a length of twenty-two feet and that sub-section AT is 2 feet long. Let it further be assumed that it is desired to interpose no time delay in the operation of switch W if the speed of a vehicle moving down'the stretch is greater than 4 miles per hour, that it will be safeto reverse the switch in 3 seconds after a vehicle vacates section AT if the vehicle is moving at a speed between 3 and 4 miles per hour, since a vehicle traveling at 3 miles per hour will have cleared the fouling point of the switch before a vehicle moving at the maximum speed for the yard will reach, that point if the slow vehicle is provided with an additional 3 seconds in which to travel, and that it will be safe to reverse the switch 5 seconds after a vehicle vacates section AT if it is moving ata speed less than 3 miles per hour since a vehicle travcling atthe minimum speed for the yard .will clear the fouling point of the switch before a following vehicle moving at the maximum speed for the yard will reach that point if the slow vehicle is given an additional 5 seconds in which to travel. It is possible to interpose an additional time delay in the operation of switch W for all vehicles to prevent the operation of the switch while a vehicle'is traveling on the switch points. However, this forms no part of the present invention and will not be considered in the following description.

. When a vehicle enters the'detector section I-II, its wheels and axles will shunt relays BTR and ATR and both of these relays will release. Upon the release of relay ATR, both the energizing and stick circuits for relay TZPR will'become open at front contact a of relay ATR and, accordingly, relay TZPR will release. Upon relay TZPR releasing, the energizing circuit for valve magnet NM will become open at front contact e of relay TZPR. The energizing circuit for magnet RMis also open at front contact e of relay TZPR so that, at this time, switch W cannot be operated from its present normal position to its reverse position by movement of lever K from its L position to its R position. Furthermore, with relays ATR and BTR both released, a second stick circuit for relay IWLR will become established, which circuit may be traced from positive terminal B of battery LB, over back contact b of relay ATR, back contact a of relay BTR, front contact b of relay IWLR, and the winding of relay 1WLR to negative terminal N of battery LB. Relay 1WLR will not release during the period that relays ATR and BTR transfer their contacts from front to back since relay IWLR is provided with a slow release characteristic which will be described in more detail later. With relay IWLR remaining picked up, the previously traced first stick circuit for relay 2WLR will remain established and relay 2WLR will remain picked up.

Upon the front of thevehicle passing through the light beam being emitted by lamp PL, light responsive unit PC will cease to supply energy to relay ZR and, accordingly, relay ZR will release. Upon relay ZR releasing, the energizing circuit for relay TZPR will be opened at an additional point, and a first energizing circuit for relay IWLR will become established. This energizing circuit may be traced from positive terminal B of battery LB, over back contact b of relay TZPR, back contact b of relay ZR, and the winding of relay IWLR to negative terminal N of battery LB. Furthermore, a first energizing circuit will become established for relay 2WLR, which circuit may be traced from positive terminal B of battery LB, over back contact 0 of relay TZPR, back contact 0 of relay ZR, and the winding of relay ZWLR to the negative terminal N of the battery LB. The two last traced energizing circuits have no effect upon the system at this time since relays 1WLR and ZWLR are maintained in their picked up positions by their stick circuits.

As long as the vehicle occupies a portion of sub-section BT, both relays ATR and BTR will remain released and the system will remain in the previously described condition. However, upon the rear of the vehicle passing beyond the light beam, relay ZR will pick up and thereby close its front contact a and open its back contacts b and c, but this will have no efiect on the system at this time. Relay ZR along with its associated light responsive unit PC and lamp PL are included in the arrangement in order to prevent the apparatus from falsely clearing the switch movement WM under certain conditions. With the .detecr tor track circuit of extremely short length (only 22 feet), it is possible that the wheels of a car mightbridge the length of the section. If this happens, relays ATRand BTR- will pick up, thereby reestablishing the energizing circuit for relay TZPR which will pick up. With relay TZPR picked up, energy will be supplied to.v either of the valve magnets of switch movement WM, thereby creating a dangerous'condition in which theswitch may be moved while a car is passing over'it. Accordingly, there is provided the relay ZR, which is, responsive. not to the shunt,- ing of a track circuit'but'to' the physi'caloccupancy, of 'a portion of the detector section by a vehicle. With a vehicle cutting off the lightbeam'from light responsive unit PC, relay ZR will remain released and thereby prevent relay TZPR from picking up to clear switch. movement WM. Furthermore, with relays. IWLR' and ZWLR energized over their first energizing circuits, .they will not release prematurely, thereby lnterposing an unnecessary time delay in the operation of. Switch; movement WM, which delay will be more fully explained subsequently.

it will be obvious that the light unit and. light, resl'gQnsive unit arrangement shown could be replaced; by some other type of intrusion detector, such as radar. It will also be obvious that the stick. circuit for relay TZPR'is provided to prevent the possible d'eenergization of relay TZPR due to an interruption ofthe light beamrby a person Walking through it, or for some. reason other than a railway vehicle moving through the detector section.

When the rear wheels of the vehicle clear insulated joint 3a, relay BTR will become energized. and will, pick up, but relay ATR will remain deenergized'since it is stillbeing shunted. by the wheels and axles of thevehicle. Accordingly, the previously'traced second stick circuit for relay IWLR will become open atback contact a. of relay BTR and relay IWLR will become. deenergized. Relay IWLR is provided with a, slow. release characteristic which will keep the armature of the relay picked up for .34 seconds after the winding of relay IWLR' becomes deenergized. This slow. release period has been selected because it is equivalent to the time it, will takev a vehicle traveling at 4 miles per hour to travela distance of Zfeet, namely the length of measuring section AT; It will be clear that other. slow release periods. for. relay IWLR may be used if the critical speed is changed or the length of measuring section AT' is. altered.

If the vehicle is traveling at a, speed greater than 4 miles per hour, the rear. wheels of the vehicle, will vacate section AT in atime less than .34 second and, upon the rear wheels vacating section AT, relay AIR will pick. up and reestablish the first traced stick circuit. for. relay llWLR. Accordingly, relay IWLR Will. nqtrelease upon a train moving faster than 4.m iles per hour. traversing the measuring section and the system will be, immediately restored to its. normal condition. If lever K. isgnowthrown to its right-hand or. R position, valve, magnet RM" will become energized and the switch. movement WM will move switch W to its reverse position.

However, if the vehicle is moving between the speed of 3 and 4 miles per hour, the rear wheels of thevehicle. will occupy section AT for a. period of. more than .34 second after they vacate section, BT. and, accordingly, relay IWLR will release. Therefore, the first stick circuit for relay ZWLR will become open at from. contact, a of relay IWLR, but relay ZWLR will not immediately. release because of. its slow release characteristic. The slow release characteristic of relay 2WLR, is. so selected that relay ZWLR will release in a periodof time equivalent to the diiterence in time it wouldtake a vehicleto traverse section AT traveling at 4 miles per hour and traveling at 3 miles per hour. Again, this time will depend. on the assumed critical speeds and the length, of section AT; This time is .12 second for the distance and speed chosen. Assuming the vehicle is traveling at greater than 3 miles per hour, it will vacate section AT in less than .12 second after relay IWLR releases. Accordingly, relay ATR will pick up and establish a second stick circuit for relay 2WLR, which circuit may be traced from positive terminal B of battery LB, over front contact b. of relay ATR, front contact a of relay BTR, back contact a of relay llWLR, front contact a of relay ZWLR, and the winding of relay ZWLR to negative terminal N of battery LB. Accordingly, relay ZWRL will remain picked up. Furthermore, upon relay ATR picking up, the previously traced energizing circuit for relay TZPR will be reestablished and relay TZPR will pick up. Therefore, an energizing circuit for time element relay ITER will become established, which circuit may be traced from positive terminal B of battery LB, over front contact d of relay TZPR, back contact c of relay IWLR, and the winding of relay lTER to negative terminal N of battery LB. Upon relay lTER becoming energized it will open its checking contact a but will not close its front contact b for a predetermined time interval, here selected at 3 seconds, although other time intervals may be used. The selected interval should preferably be long enough to assure that a vehicle moving at the measured speed will be clear of the fouling point when a vehicle moving at maximum speed reaches that point. Upon the checking contact a of relay lTER opening, the energizing circuit for relay TZPR will become open but relay TZPR will remain energized over its previously traced stick, circuit. Upon the expiration of the 3 seconds, relay lTER will close its front contact I) and, accordingly, Will closev a second energizing circuit for relay lWLR which may be traced from positive terminal B of battery LB, over front contact b of relay ATR, front contact a of relay BTR, front contact b of relay iTER, frontcontact b of relay Z'WLR, and the winding of relay IWLR to negative terminal N of battery LB. Therefore, relay lWLR will pick up and reestablish its first stick circuit and the previously traced first stick circuit for relay ZWLR. Furthermore, upon relay IWLR picking up, the energizing circuits for valve magnets RM and NM are conditioned for switch operation. Accordingly, if lever K is thrown to its R position, valve magnet RM will become energized over a circuit which may be traced from positive terminal B' of battery LB, over front contact e of relay TZPR, front contact d of relay IWLR, the lever contact closed with lever K in its R position, and the winding of valve magnet RM to negative terminal N of battery LB; Accordingly, the switch movement WM will operate switch W to its. reverse position. lt will be clear that during the entire time that the vehicle occupied either section BT and AT, relay. TZPR was released and, accordingly, regardless of the position of lever K, neither valve magnet could be energized. Furthermore, as long as relay IWLR. was deenergized, neither valve magnet could be energized to operatethe switch. Therefore, a time delay of 3 seconds has been effected, thereby assuring that if any vehicle moving at a rate much greater than the first vehiclewas following immediately behind the first vehicle, the second vehicle will move onto the same track as the first vehicle and thereby preclude the possibility of cornering.

Now let it be assumed that a vehicle moves down section III at a speed less than three milesper hour. When this is the case, the rear wheels of the vehiclewill occupy section AT for a period of time greater than .46 second. Upon the expiration of .34 second, relay IWLR will re.- lease as previously described and thereby deenergize relay ZWLR. However, relay ZWLR will remain picked up for .12 second after relay IWLR releases. Since the vehicle is traveling at less than three miles per hour, relay ZWLR will release before the vehicle vacates section AT. When the vehicle finally does vacate section AT, relay TZPR will become energized over its previously traced energizing circuit and thereby establish the energizing circuit for time element relay lTER, which circuit has already been traced. Furthermore, with relay ZWLR released, upon the picking up of relay TZPR an energizing circuit will be established for time element relay ZTER, which circuit may be traced from positive terminal B of battery LB, over front contact d of relay TZPR, back contact c of relay 2WLR, and the winding of relay ZTER to negative terminal N of battery LB. Relay ZTER will immediately open its checking contact a but is designed to not close its front contact b for a period of seconds. Upon the expiration of 3 seconds after the vehicle vacates section AT, relay ITER will pick up and close its front contact b but this will not energize relay 1WLR over its second energizing circuit since that circuit will remain open at front contact b of relay 2WLR. Upon the expiration of another 2 seconds, relay ZTER will close its front contact b and, accordingly, will establish a second energizing circuit for relay 2WLR, which circuit may be traced from positive terminal B of battery LB, over front contact b of relay ATR, front contact a of relay BTR, back contact a of relay IWLR, front contact b of relay 2TER, and the winding of relay 2WLR to negative terminal N of battery LB. Upon relay 2WLR picking up it will establish its previously traced second stick circuit and it will cause relay 2TER to become deenergized and to release. Furthermore, upon relay 2WLR picking up, the previously traced second energizing circuit for relay 1WLR will become established and relay 1WLR will pick up. Upon relay IWLR picking up it will reestablish its first stick circuit and will close the energizing circuit for either of the valve magnets RM and NM, depending on the position of lever K. Furthermore, upon relay 1WLR picking up, the previously traced energizing circuit for relay 1TER will become open and relay ITER will release. With relay IWLR now picked up, the second energizing circuit for relay ZWLR will become open at back contact a of relay 1WLR, but the first stick circuit for relay ZWLR will be reestablished and relay 2WLR will remain stuck up. In this manner the system will be restored to its normal condition. It should be noted that with relay IWLR released for the full time interval of operation .of relay ZTER, the switch W could not have been thrown until a full 5 seconds after the vehicle vacated section AT. If a second vehicle were to follow shortly behind the first vehicle, it will move down the same track as the first vehicle and thereby preclude the possibility of cornering.

It should be clear that if it is desired to introduce only one time delay depending upon whether the speed of a cut was above or below a single predetermined value, such as four miles per hour, that relays ZWLR and ZTER and their associated circuits can be omitted and the system will function as described for a vehicle moving at speeds greater or less than four miles per hour. In view of this, the remaining embodiments of my invention, as shown in Figs. 2 and 3, will be described with only one control relay IWLR and only one means for introducing a time delay.

In the described operation of the embodiment shown in Fig. 1, it will be clear that the apparatus is controlled by the speed of the rear set of wheels of a vehicle. It is also possible to govern the apparatus by the speed of the front wheels of a vehicle, as is shown in Fig. 2. Referring to Fig. 2 it will be seen that the short measuring section AT is at the entrance end of the detector section made up of sub-sections AT and BT. For the sake of clarity the dimensions of section AT will be two feet long and that of BT twenty feet long, thereby making the total detector section III twenty-two feet long, as it was in Fig. 1. The system is shown in Fig. 2 in its normal condition with relays ATR and BTR energized by track battery TB, and relay ZR energized by light responsive unit PC which is actuated by lamp PL. With the relays so energized, an energizing circuit is established for energizing relay TZPR, which circuit may be traced from positive terminal B of battery LB over front contact a of relay ATR, .front contact a of relay BTR, front contact a of relay ZR, checking contact a of relay lTER whic relay is deenergized, and the winding of relay 8 TZPR to negative terminal N of battery LB. Furthermore, relay TZPR is supplied with energy over a stick circuit which may be traced from positive terminal B of battery LB, over front contact a of relay ATR, front contact a of relay BTR, front contact a of relay TZPR, and the winding of relay TZPR to negative terminal N of battery LB. At this time control relay IWLR will be energized by its first stick circuit which may be traced from positive terminal'B of battery LB, over front contact a of relay ATR, front contact b of relay BTR, front contact a of relay 1WLR, and the winding of relay IWLR to negative terminal N of battery LB. The switch W is shown in its normal position in which traffic will move onto track T1. Normal valve magnet NM is energized by a circuit which may be traced from positive terminal B of battery LB, over front contact 0 of relay TZPR, front contact 0 of relay IWLR, contact L of lever K, and the valve magnet NM to negative terminal N of battery LB. Again assuming that the critical speed is four miles per hour, relay 1WLR will be provided with a slow release time of .34 second since that is the time it will take a vehicle moving four miles per hour to traverse measuring section AT. Let it now be assumed that a cut enters section I-II traveling at a speed greater than four miles per hour. As the cut enters section I-II, relay ATR will become shunted by the wheels and axles of the train and accordingly will release, thereby opening the previously traced energizing and stick circuits for relay TZPR which relay will also release. Furthermore, upon relay ATR releasing the previously traced first stick circuit for relay IWLR will become open at front contact a of relay ATR and, accordingly, relay IWLR will become deenergized. However, relay IWLR will not immediately release because of its slow release characteristic. With the cut traveling at a speed in excess of four miles per hour, the front wheels of the cut will enter section BT prior to the time that relay IWRL will release and accordingly relay BTR will release. Of course, relay ATR will remain released. Upon the release of relay BTR, a second stick circuit will become established for relay IWLR, which circuit may be traced from positive terminal B of battery LB, over back contact a of relay ATR, back contact b of relay BTR, front contact a of relay IWLR, and the winding of relay IWLR to negative terminal N of battery LB. Therefore relay IWLR will not release. When the vehicle interrupts the light beam emitted by the light unit PL, relay ZR will release and open the energizing circuit for relay TZPR at another point. This will have no effect upon the circuit. It will be obvious that the function of relay ZR in the second embodiment is the same as that described with respect to Fig. 1.

Upon the rear wheels of the cut vacating section I-II, relays ATR and BTR will both pick up and relay ZR will already be picked up. Therefore, the previously traced energizing circuit of the relay TZPR will become reestablished. Accordingly, relay TZPR will pick up and reestablish the energizing circuit for valve magnet NM. If at any time during the further movement of the vehicle lever K is thrown to its right-hand or R position, reverse valve magnet RM will become energized and switch W will be operated to its reverse position. Therefore there will be no time delay introduced in the operation of switch W.

Assuming that a vehicle traveling at a speed less than four miles per hour enters section III, relay ATR will release and thereby deenergize relay TZPR and open the first stick circuit for relay IWLR. Since the vehicle is traveling at less than four miles per hour, its front wheels will occupy section AT for a time greater than .34 second and, accordingly, relay IWLR will release prior to relay BTR being shunted by the wheels and axles of the vehicle. Upon relay IWLR releasing the energizing circuits for the valve magnets will become open at a second point but this will have no immediate effect upon the system. When the vehicle enters section BT, relay BTR will may be traced from positive terminal B of battery LB,

over front contact b of relay TZPR, back contact b of relay IWLR, and the winding of relay lTER to negative terminal N of battery LB. Accordingly, relay lTER will open its checking contact a but will not close its front contact b for a predetermined time interval which, for the sake of explanation, will be assumed to be seconds for reasons which have heretofore been made clear. Upon checking contact q of relay lTER opening, the energizing circuit for relay TZPR will become open but relay TZPR will remain energized over its previously traced stick circuit. It will be noted that as long as relay 1WLR is released it will be impossible to move switch W to its reverse position since the energizing circuits for the valve magnets are open at front contact 6 of relay IWLR.

Upon the 5 seconds time interval expiring, relay lTER will close its front contact I; and thereby establish a circuit for energizing relay IWLR, which circuit may be traced from positive terminal B of battery LB, over front a contact a of relay ATR, front contact 12 of relay BTR, front contact I; of relay ITER, and the winding of relay IWLR to negative terminal N of battery LB.

Therefore, relay IWLR will pick up and reestablish its previously traced first stick circuit and, furthermore, with relay 1WLR now picked up, relay ITER will become deenergized and thereby release, thus opening its front contact I and closing its checking contact a. This will open the energizing circuit for relay IWLR but relay 1WLR will remain energized over its first stick circuit. Furthermore, the previously traced energizing circuit for relay TZPR will be reestablished. Upon relay IWLR picking up, it will place valve magnets NM and RM in a condition to be energized and, accordingly, the switch may now be operated to either its normal or reverse position depending on. the position of lever K. It will be seen therefore that as long as a vehicle is moving at less than four miles per hour, the switch S cannot be operated until 5 seconds after the vehicle vacates section III, which time delay is interposed by the operation of relay lTER. In this way the first vehicle will be given sufficient time to clear the fouling points of the switch W and, accordingly, a following fast moving vehicle will not corner the initial vehicle.

The embodiments shown in Figs. 1 and 2 utilize a time delay based upon the operation of a time element relay. Such a time delay is based purely on a predetermined time interval. It is also possible to delay the operation of switch S until a slow moving. vehicle traverses a predetermined distance. Such an arrangement is shown in Fig. 3. In order to accomplish. this, an insulated track section CT must be provided. in both adjacent tracks T1 and T2. A track circuit associated with sections CT is provided in advance of section AT and this track circuit is energized by track battery CTB which energizes a track relay CTR. In order to include both tracks in the track circuit, a jumper 6 and the usual frog arrangement at the switch are employed to connect the rails in multiple.

As shown in Fig. 3, the apparatus is in its normal condition in which t t a k relay ATR. BTR R a all energized by their associated track batteries. Accordingly, relay TZPR is energized by a circuit which may be traced from positive terminal B of battery LB, over front contact a of relay ATR, front contact a of relay BTR, front contact a of relay ZR, the winding of relay TZPR to negative terminal of battery LB. Furthermore, relay TZPR i'sat this time energized by its stick circuit which may be traced from positive terminal B of battery LB, over front contact a of relay ATR, front contact a of relay BTR, front contact a of relay TZPR, and the winding of relay TZPR tonegative terminal N of battery LB. Furthermore, relay lWLR is energized over a first stick circuit which may be traced from positive terminal B of battery LB, over front contact b of relay BTR, front contact b of relay ATR, front contact a of relay IWLR, and the winding of relay IWLR to negative terminal N of battery LB.

As shown traffic control lever K is in its left-hand or L position and accordingly valve magnet NM is energized over a circuit which may be traced from positive terminal B of battery LB, over from contact c of relay TZPR, front contact 0 of relay -1WLR, the contact closed when lever K is in its L position, and the winding of valve magnet NM to negative terminal N of battery LB. With valve magnet NM' so energized, switch W will be in its normal position in which traffic will move onto trackTl.

Assuming that a vehicle moves down the stretch in the indicated direction at a speedgreater than the critical speed, herein assumed to be four miles, per hour, as the front wheels of the cut enters section III, relays ATR and BTR will both release due. to the fact that they are shunted by the wheels and axles of the vehicle. Accordingly, relay TZPR will release but relay IWLR will remain energized over a second stick circuit which may be traced from positive terminal B of battery LB, over back contact b of relay BTR,, back contact b of relay ATR, front contact a of relay lWLR, and the winding of relay EWLR to negative terminal N or. battery LB. Due to the slow release characteristic of relay IWLR, it will not release during the time it takes relaysBTR and ATR to release their armatures. Upon the vehicle interrupting the light beam emitted by light source PL, relay ZR will release and thereby close a first energizing circuit for relay 1WLR which circuit maybe traced from positive terminal. B of battery LB, over back contact I; of relay TZPR, back contact b of relay ZR, and the winding of relay llWLR to negative terminal. N of battery LB. Since relay EWLR is, at this time energized over its second stick circuit, the establishment of the energizing circuit has no effect upon the apparatus.

When the front wheels of the cut enter section AT there will be no effect upon the apparatus hence both relays ATR and BTR remain shunted. However, upon the rear wheels of the cut passing insulated joint 3a, relay BTR will pick up thereby opening the second traced stick circuit for relay IWLR. As in the other embodiments heretofore described, relay IWLR will have a slow release characteristic whichwill maintain its armature in a picked up positionfor .34 second after it becomes deenergized. Accordingly, with the cut traveling at a speed greater than four miles. per hour, the rear wheels of the cut will vacate the two foot long measuring section AT in a time less than .34 second at which time relay ATR will pick up and. reestablish the first stick circuit for relay IWLR, thereby preventing that relay from releasing. Furthermore, relay ZR will pick up upon the light responsive unit being reactuated by the light beam emitted by the light source PL and, accordingly, upon the cut vacating section AT, an energizing circuit will be immediately established for energizing either the normal or reverse valve magnets NM and RM depending on the position of lever K. It will be seen therefore that with a cut moving at a speed of four miles per hour or greater, there will be no time delay interposedin the operation of the switch W and it may be moved upon section III being vacated.

Now let it be assumed that a vehicle enters section -11 traveling at a speed less than four miles per hour. Upon the front wheels of the cut entering section BT, relays BTR and ATR will release as already described,

11 and relays ZR and TZPR will both release. Relay 1WLR will remain energized over its second stick circuit as already described and this stick circuit will not be opened until the rear wheels of the vehicle vacate section BT at which time relay BTR will pick up and open the second traced stick circuit for relay 1WLR at back contact b of relay BTR. With the vehicle traveling at a speed less than four miles per hour, the rear wheels of the vehicle will occupy section AT for a time in excess of .34 second. Accordingly, relay IWLR will release. Upon the rear wheels of the vehicle vacating section I-II, relay ATR will pick up and reenergize relay TZPR which will pick up. However, the energizing circuit for the valve magnets RM and NM will now be open at front contact of relay IWLR and will remain open until relay IWLR is again energized. At this time, a circuit for energizing an auxiliary relay IWLTPR, which circuit may be traced from positive terminal B of battery LB, over front contact 0 of relay ATR, back contact b of relay 1WLR, front contact a of relay CTR, and the winding of relay IWLTPR to negative terminal N of battery LB will be open at front contact a of relay CTR, which is now released due to its being shunted by the wheels and axles of the vehicle. It will be clear that as long as the vehicle occupies section CT thereby shunting relay CTR, this energizing circuit for relay IWLTPR will remain open. Section CT may be of any desired length but preferably will be long enough to insure that a vehicle, prior to vacating the section, will have moved a sufficient distance down either track to insure that a following vehicle moving at maximum yard speed will not reach the fouling point of switch W until the slow vehicle has cleared that point. When the rear wheels of the vehicle vacate section CT, relay CTR will pick up and thereby energize relay IWLTPR which relay will pick up and close a second energizing circuit for relay IWLR. The second energizing circuit for relay IWLR may be traced from positive terminal B of battery LB over front contact b of relay BTR, front contact b of relay ATR, front contact a of relay IWLTPR, and the winding of relay 1WLR to negative terminal N of battery LB. Upon relay IWLR picking up the valve magnets NM and RM will be put in a condition to be energized and, accordingly, the switch W can now be operated to its desired position. Furthermore, upon relay IWLR picking up, the energizing circuit for relay IWLTPR will become open at back contact b of relay 1WLR and, accordingly, relay IWLTPR will release. Upon relay lWLTPR releasing, the previously traced second energizing circuit for relay 1WLR will become open at front contact a of relay 1WLT PR but relay IWLR will not release since it is now being energized over its previously traced first stick circuit. In this manner the apparatus will be restored to its normal condition.

It will be clear from the above description that if a vehicle is moving at a speed below four miles per hour, then no movement of the switch to its reverse position will be possible until the vehicle vacates section CT at which time the vehicle will be beyond the fouling point of the switch and, accordingly, it will be impossible for any cornering to take place.

It should be pointed out that the slow release relays IWLR and 2WLR shown in the three embodiments of my invention are designed to have a particular slow release characteristic at the highest voltage to which they will be subjected, namely the rated voltage for a battery LB. Accordingly, in the event that the voltage on battery LB decreased due to undue drain or age, the slow release relays will merely release in a time which is less than the prescribed release time, and the system will therefore operate on the safe side.

Although I have herein shown and described only three forms of my invention, it is to be understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. Control apparatus for a railway track switch in a classification yard connecting a first stretch of track to second and third diverging track stretches, comprising, in combination, operating means connected to said switch for moving it between first and second positions in which cars on said first stretch are routed to said second and third track stretches, respectively, means for measuring the speed of a cut of one or more cars approaching said switch on said first stretch, and timing means controlled by said measuring means and operatively connected to said operating means to interrupt the operation thereof for a time interval after a cut has passed over said switch dependent on the speed of said cut.

2. Means for preventing the cornering of a first cut of one or more cars passing over a railway switch in one of two operable positions by a following cut of one or more cars passing over said switch in the other of said positions, said switch being provided with control means for moving it from one to the other of its positions, comprising, in combination, means responsive to the speed of cuts approaching said switch, and means controlled by said speed responsive means for delaying the operation of said control means after said first cut has passed over said switch for a time in accordance with the speed of said first cut sufiicient to prevent cornering if said first and second cuts pass over said switch in different positions thereof.

3. Means for delaying the operation of a railway switch after a first cut of one or more cars has passed thereover to prevent a following cut from colliding with the rear end of the first cut, comprising, in combination, switch control means for moving said switch from a first to a second position, means located in advance of the switch for measuring the speed of said first cut, means actuated from a first to a second condition by a car entering said switch, and means controlled by said speed measuring means and said car actuated means for preventing the operation of said switch control means for a time after said car actuated means has moved from its second to its first position in accordance with the speed of said first cut.

4. In combination with a railway track switch having two operative positions for diverting railway vehicles moving along a stretch of track onto one or the other of two adjacent tracks, depending on the position of said switch, speed measuring means located along said stretch immediately in approach to the switch for measuring the speed of vehicles entering the switch, switch operating means for operating said switch between its two positions, circuit means for controlling said switch operating means, and a contact in said circuit means controlled by said speed measuring means in response to a vehicle entering said switch below a predetermined speed to interrupt said circuit means for a time sufiicient to permit said vehicle to clear the fouling point of the switch.

References Cited in the file of this patent UNITED STATES PATENTS 2,022,708 Crago Dec. 3, 1935 2, 62,835 Schwendt et al. Dec. 1, 1936 2,076,955 Livingston Apr. 13, 1937 ,367,732 Haines Jan. 23, 1945

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