US2734130A - Graduated time control system for - Google Patents

Description

Feb. 7, 1956 E, DODD ET AL 2,734,130

GRADUATED TIME CONTROL SYSTEM FOR HIGHWAY CROSSING SIGNALS Filed Oct. 30. 1952 INVENTORS w +1 Arthur E Dodd and J g q BY James K21 710120 I-\ 5 w. k. Saar THEIR A T TORNE Y United States Patent GRADUATED TIME CONTROL SYSTEM FOR HIGHWAY CROSSING SIGNALS Arthur E. Dodd, Edgewood, and James E. McMahon, Penn Township, Allegheny County, Pa., assignors to Westinghouse Air Brake Company, Wiimerriing, Pa., a corporation of Pennsylvania Application October 30, 1952, Serial No. 317,758

5 Claims. (Cl. 246130) Our invention relates to apparatus for providing graduated time control of a warning device located at the intersection of a highway with a railway for the purpose of warning users of the highway of the approach of a train, for initiating the operation of a highway crossing signal at substantially the same period of time before a train approaching the crossing reaches the crossing regardless of the speed of the train. More particularly, our invention relates to apparatus for controlling a plurality of highway crossing signals, disposed at crossings which are relatively close to each other, in such manner that each of the signals will start to operate at substantially the same period of time before a train approaching the crossing reaches the crossing, regardless of the train speed.

Highway crossing signals are sometimes arranged to be actuated immediately upon the entrance of a train into a section of track in which the crossing is located. Depending upon the speed of the train, the highway trafiic will receive more or less warning time; if the train is moving at a relatively high speed, it will traverse the section rapidly thus giving the highway traffic a relatively short warning period, and if the train is moving slowly, the warning period will be relatively long. In such systems, the length of the track section is normally so arranged that a train moving at maximum permissive speed will actuate the highway crossing signal a minimum safe time prior to its crossing the highway. With such an arrangement, slow moving trains give an unduly long warning period. This situation may lead to highway traffic becoming careless at the crossing and often to highway trafiic ignoring the signal altogether. Such potential indifference on the part of highway trafiic is clearly unsafe and undesirable.

To help in overcoming a prolonged warning period where relatively long track sections are used, highway crossing signals are sometimes set into operation a predetermined period of time after a train enters the track section which includes the highway crossing. However, because the time delay is the same for both slow and fast moving trains, such a scheme does not wholly overcome the principal objection to the arrangement already discussed, and a prolonged warning time, with its possible undesirable results, is still a distinct possibility.

A further improvement in overcoming prolonged warning periods at highway crossings has been the use of graduated time control systems. These systems employ time element means to measure the speed of the train or vehicle moving along the stretch and, upon measuring the speed, introduce means proportional to the train speed for delaying the release of the highway crossing signal control relay which actuates the signal. These time delay means may be thermal elements, slow acting relays or capacitors.

In the past, when capacitors were employed to effect the delay in the release of the signal control relay, the capacitors have been normally charged and were sequentially connected in multiple with the winding of the highway crossing signal control relay by the release of a normally energized time element means. Such a system does not work on a fail-safe basis, and the accidental deenergization of a time element means, due to a broken wire or for some other reason, would introduce an excessive amount of capacitance across the winding of the signal control relay. Such an occurrence will result in a prolonged time delay before the signal control relay will release, thereby giving the highway traflic an unduly short warning time.

lniview of the foregoing, one object of our invention is to provide apparatus for actuating a highway crossing signal in such manner that highway traffic using the crossing will receive approximately the same warning time regardless of the speed of an approaching train.

Another object of our invention is to provide apparatus for sequentially actuating highway crossing signals located at several adjacent highway crossings in such a manner as to afford to the trafiic on each highway approximately the same warning time regardless of the speed of an approaching train.

A further object of our invention is to provide a system of the type described which will operate on a failsafe basis.

According to our invention, a stretch of railway track is divided into several sections by insulated joints. One of these sections is of a predetermined length and will be called the timing section. A second section, called the warning section, is intersected at its end remote from the timing section by a highway. Each of these track sections is provided with the usual track circuit including a track relay. The track relay which is controlled by the track circuit associated with the timing section controls the supply of energy to a number of time element relays which are normally deenergized. Upon energization, the time element relays sequentially close their timing contacts and subsequently hold them closed as long as the stretch is occupied. The timing contacts control circuits each of which when closed places a snubbing capacitor across the winding of an auxiliary relay. The auxiliary relay is energized over an energizing circuit controlled by the track relay for the warning section, and when this circuit is opened this relay will release after a time delay which depends upon the total snubbing capacitance placed across the winding of the auxiliary relay by the time element relays. Since the number of time element relays which have closed their timing contacts will depend upon the time required for the train to traverse the timing section, it will be obvious that the release time of the auxiliary relay will be inversely proportional to the speed of the train.

The snubbing capacitors are proportioned to have the auxiliary relay release within a predetermined time range prior to the train reaching the highway crossing. When the auxiliary relay releases, a warning signal at the highway crossing is energized to warn traffic of the approaching train.

Other objects of our invention will appear hereinafter as the characteristic features and mode of operation of apparatus embodying our invention are described in detail.

We shall describe one form of graduated time control system embodying our invention, and shall then point out the novel features thereof in claims.

In the accompanying drawings, Fig. l is a diagrammatic view showing a preferred form of a graduated time control system embodying our invention.

Fig. 2 is a diagrammatic view of a time element relay suitable for use in our graduated time control system.

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

Referring now to Fig. 1, a stretch of railway track made up of rails 5 and 6 is divided into track sections 1T, 2T and ET by insulated joints 7. Each of these track sections is provided with the usual tracltcircuit including, as here shown, track batteries 1TB, 2TB and 3TB, respectively, connected across the rails at one end of the associated section, and track relays lTR, ZTR and 3TR, respectively, connected across the rails at the opposite end of the associated section. At the end of the section 2T remote from section IT, a highway A intersects the stretch of track, and at the end of section 3T remote from section 2T, a highway B intersects the stretch of track. Adjacent each railway-highway grade crossing, a highway crossing signal is placed. As here shown, these signals are bells 2C5 and 3C8 located at highways A and B, respectively, but it will be understood that other types of highway crossing signals could be employed in connection with our graduated time control system.

Signal 3CS is energized over an obvious circuit which is controlled by a back contact a of a control relay BXR. Relay BXR is at times energized by a battery LB over a first circuit including front contact a of track relay 3TH.

and front contact 0 of a control relay AXR, and at other times by a second circuit including a front contact 0 of a stick relay CKSR and a front contact a of an auxiliary relay BZR. Relay BZR is energized by a circuit which can be traced from the positive terminal B of battery LB,over front contact b of relay 3TR, front contact b of control relay AXR, and the winding of relay BZR to the negative terminal N of battery LB.

Associated with relay BZR is a timingunit U2 comprising a plurality of' snubbing capacitors C7 to C13 and snubbing resistors R7 to R13, the function of which will be described presently.

Highway crossing signal ZCS is energized by an obvious circuit including a back contact a of control relay AXR. Relay AXR is at times energized by a first circuit which can be traced from the positive terminal B of battery LB, over front contact d of stick relay CKSR, front contact a of an auxiliary relay AZR, and the winding of relay AXR to negative terminal N of. battery LB, and at other times over a second circuit passing from positive terminal B of battery LB, through front contact b of relay ZTR, and the winding of relay AXR to the negative terminal N of battery LB. Relay AZR is energized by battery LB over front contact 0 of a repeater relay 2-3TPR.

Associated with relay AZR is a second timing unit U1. comprising a plurality of snubbing capacitors C1-C6 and snubbing resistors Rl-R6, the functions of which will be described presently.

Repeater relay 2-3TPR is energized by a circuit which can be traced from the positive terminal B of battery LB, over front contact a of relay 3TR, front contact r: of relay ZTR, and the winding of relay 2-3TPR to the negative terminal N of battery LB.

Stick relay CKSR is energized by an energizing circuit which can be traced from the positive terminal B of battery LB, over back contact a of relay 1TR,the checking contacts a of each of a plurality of normally deenergizcd time element relays lTER to GTER, front contact b of relay 2-3TPR, and the winding of relay CKSR to the negative terminal N of battery LB. Stick relay CKSR is provided with a first stick circuit which can be traced from the positive terminal B of battery LB, over back contact a of relay 1TR, front contact 0 of relay CKSR, front contact b of. relay 2-3TPR, and the winding of relay CKSR to'the negative terminal N of battery LB.

The time element relays lTER to GTER may be of any suitable type- As shown in Fig, 2, these time element rclays are a modification of the time element relay described and claimedin Letters Patent of the United States No. 1,966,965, granted to Branko Lazich and Harry E. Ashworth, on July 17, 1934, for Electrical Relays. For the purpose of this disclosure, it is sutficient to point out that each of these relays comprises a stepping magnet D and a clutch magnet G. The stepping magnet is adapted to be supplied with'current impulses froma code transmitter CT over a back contact d of the time element relay in a manner which will be madelclear presently, and controls an armature 14 in such a manner that when stepping magnet D is energized, the armature 14 will be oscillated in step with the current impulses supplied to the stepping magnet. The armature 14 actuates a pawl 15 which cooperates with a ratchet wheel 13, the parts being so arranged that oscillation of the armature 14 will cause a step by step rotation of the ratchet wheel in a clockwise direction. The ratchet wheel 13, in turn, is operatively connected with a planetary contact arm 16 in such a manner that when a clutch wheel 11 which is also connected with the arm is engaged by a clutch 10, rotation of the ratchet wheel will cause corresponding rotation of the arm, but that, when the clutch is out of engagement with the clutch wheel, the arm 16 will return, due to gravity, to the position shown. The arm 16 is identical with the arm F shown and described in the abovementioned Lazich and Ashworth patent, and the detailed description of this arm is therefore deemed to be unnecessary. The clutch 10 is arranged to be moved into engagement with the clutch wheel 11 in response to energizaticn of the clutch magnet G by means of an armature 17 which is connected with the clutch. When the clutch magnet G is deenergizcd, the clutch is moved out of engagement with the clutch wheel by gravity. It should be noted that when the clutch is engaging the clutch wheel, the arm 1.6 will be held in any position to which it is rotated by the stepping magnet.

The arm 16 as here shown operates four contacts a, b, c and (l. The contact a is a checking contact for checking when the arm 16 occupies its normal position and is arranged to be closed, by means of an insulating strip 18 secured to the arm 16, when and only when the arm occupies its full normal position, and to open immediately upon the arm startirng to move away from this position. This checking contact is adapted to be included in the energizing circuit for the stick relay CKSR and its function will be more clearly described later. The contacts b and c are timing contacts, and are arranged to be closed at the expiration of the time interval for which the time element relay is set, by engagement of an insulating piece 19 secured to the arm 16.

The contact d is provided for the purpose of deenergizing the stepping magnet D following the completion of the time interval, and is normally closed, but is arranged to become opened following the closing of the contacts b and c in a manner which will be apparent from an inspection of Fig. 2.

The time required to close the timing contacts b and 0 depends upon the are through which the arm 16 has to be rotated before the insulating member 19 moves into engagement with the movable contact fingers of contacts b and c and on the frequency of the time impulses which are supplied to the stepping magnet D by the code transmitter CT. The length of the arc to which the arm 16 has to be rotated to close the contacts b and 0 can be adjusted in a manner described in the above mentioned Lazich and Ashworth patent, while the frequency of the current impulses supplied to the stepping magnet may be varied by proper design of the code transmitter CT. It follows therefore that each time element relay can be made to. close its time contacts b and c at the expiration of any desiredtime interval after the two mag nets G and D have both become energized. Because of this adjustable timing feature, it is possible to arrange the time element relays lTR to 6T R to pick up sequentially in a manner to be described subsequently.

Although we have described the operation of one type of time element relay in some detail, it is understood that any time element means which can perform functions similar to the functions performed by the time element relay just described will be suitable for use in our invention.

The code transmitter CT which at times supplies the current impulses to the stepping magnet D of each of the time element relays, as heretofore described, may be of the conventional type well known in the coded railway signaling art. The code transmitter CT may include one or more contacts which are adapted to be opened and closed at a predetermined rate, for instance, 180' times per minute, when its operating winding is energized from a suitable source. As here shown, the operating winding of the code transmitter CT is con tinuously connected to the terminals B and N of the battery LB. Accordingly, it will be seen that the contact a of the code transmitter CT is continuously operating at the predetermined code rate.

Referring now again to Fig. 1, the clutch magnets G of the time element relays ITER to 6TER are all energized in multiple, as are the stepping magnets D. It follows that the time element relays will all be energized for the same period of time. However, the relays are so set that they do not pick up simultaneously but sequentially. That is, lTER picks up before ZTER which picks up before STER, and so on. The purpose of this will be made clear as the operation of my graduated time control system is described in detail.

With the apparatus arranged as shown in Fig. 1, when a train enters track section 1T moving in the direction indicated by the arrow, the wheels and axles of the train will shunt the track relay lTR causing it to release and close its back contact a. With contact a of relay 1TR closed and the time element relays all in their normally deenergized condition, stick relay CKSR will become energized by its previously traced energizing circuit, including checking contact a of each of the time element relays, and front contact b of relay 2-3TPR. When relay CKSR picks up it will remain energized by its first stick circuit which has already been traced. Relay 2-3TPR will remain picked up because track relays ZTR and STR are both energized.

The closing of front contact a of relay CKSR completes an energizing circuit for the normally deenergized clutch magnets G of each of the relays lTER to 6TER. These circuits are in multiple, and may be traced from the positive terminal B of battery LB over front contact a of relay CKSR, and the clutch magnet G of each of the time element relays in multiple, to the negative terminal N of battery LB. As long as the train remains in section 1T, the stepping magnets D of relays lTER to 6TER are continuously energized in multiple by a circuit which can be traced from the positive terminal B of battery LB, over contact a of a code transmitter CT, front contact a of relay 2-3TPR, and stepping magnet D of each of the time element relays in multiple, to the negative terminal N of battery LB. With the clutch and stepping magnets of the relays lTER to 6TER both energized as just described, these relays begin to operate in the manner heretofore described.

It is obvious that the amount of time it takes a train to traverse the timing section IT is dependent upon the speed of the train. For instance, assuming the timing section IT is 1125 feet long, a train moving at 70 miles per hour will take approximately 11 seconds to traverse section IT, a train moving at 60 miles per hour, 12.8 seconds; 50 miles per hour, 15.4 seconds; 40 miles per hour, 19.2 seconds; 30 miles per hour, 25.6 seconds and miles per hour, 38.4 seconds. It is clear that if ITER was set for an 11 second time delay, 2TER for a 12.8 seconds time delay, and so on to 6TER being set for a 38.4 seconds time delay, if a train moved through section IT at a speed greater than 70 miles per hour, none of the time element relays would pick up during the time the train occupied section 1T. However, if a train moved through section IT at 70 miles per hour or less, lTER would pick up; if it moved through the section at 60 miles per hour or less, lTER and ZTER would both pick up, etc., so that for a train speed of 20 miles per hour or less, all the time element relays would pick up.

Assuming that section IT is 1125 feet long and that a train moving through the section IT is traveling at the rate of 50 miles per hour, by the time the train enters the section 2T, relays ITER, ZTER and 3TER will be picked up. Although the energizing circuit for relay CKSR is interrupted at checking contact a of each of the time element relays lTER to 6TER as soon as the stepping magnets of these relays start to operate, relay CKSR will remain picked up by its previously traced first stick circuit, and the clutch magnets G of the time element relays therefore will remain energized. When the train vac-ates section 1T, relay lTR will pick up, interrupting the previously traced first stick circuit energizing relay CKSR. However, relay CKSR does not immediately release because it is a slow release relay. The purpose of this delayed release will be made clear shortly.

Upon the train entering track section 2T, the wheels and axles of the train shunt relay 2TR causing it to re lease. Upon the release of relay 2TR, the circuit for energizing auxiliary relay AXR including front contact I) of relay ZTR becomes opened, but relay AXR remains picked up because its other energizing circuit, passing from the positive terminal B of battery LB, over front contact (I of relay CKSR, front contact a of relay AZR, and the winding of relay AXR to the negative terminal N of battery LB, is closed. Also upon the release of relay 2T R, relay 2-3TPR will release due to its previously traced energizing circuit being interrupted at front contact a of relay 2TR.

Because of the slow release characteristics of relay CKSR, relay 2-3TPR will release before relay CKSR releases and upon relay 2-3TPR releasing, a second stick circuit energizing relay CKSR will be established, which stick circuit can be traced from the positive terminal B of battery LB, over front contact I) of relay CKSR, back contact b of relay 23TPR, and the winding of relay CKSR to the negative terminal N of battery LB. T herefore, relay CKSR will remain picked up. With relay CKSR remaining picked up, the clutch magnet G of each of the time element relays ITER to 6TER will remain energized. However, the stepping magnet D of each of the time element relays whose magnet D has not already become deenergized due to the opening of its contact d will now become deenergized due to relay 2-3TPR releasing. With the clutch magnets energized and the stepping magnets deenergized due to relay 2-3TPR releasing, the time element relays which have picked up, that is ITER, ZTER and STER, will stay up, and no other time element relays will pick up.

When relay lTER picked up, it closed a circuit in timing unit U1 which can be traced from the positive terminal B of battery LB, over front contact 0 of relay Z STPR, timing contact I) of relay ITER, snubbing capacitor C1, and resistor R1 to the negative terminal N of battery LB. The closing of this circuit will cause capacitor C1 to become charged up to the terminal voltage of battery LB and after the capacitor C1 is fully charged, the charging current will cease to flow in the circuit. Upon relays ZTER and 3TER picking up, similar circuits will be closed for charging capacitors C2 and C3, respectively, and it can be seen that all the charged capacitors are in multiple. The purpose of this will noW be made clear.

it is usually considered desirable that the warning time given to traffic at a railway-highway grade crossing should be within the range of 20 to 30 seconds. Assuming for the sake of explanation that track section 2T, known as the warning section, is 3000 feet long and the train is traveling at a speed of 50 miles per hour, it will take the train approximately 41 seconds to traverse section 2T. In order that the traffic on highway A gets a 20 second warning, relay AXR, which controls highway crossing signal 2CS, must release approximately 21 seconds after the train enters the warning section 2T. As the train enters the warning section, relays 2TR and 2-3TPR release for reasons already made clear. Thus,

the normal energizing circuit for auxiliary relay AZR is opened at front contact c of relay 2-3TPR as soon as the train enters section 2T. However, relay AZR does not release immediately due to the presence of the the capacitors C1, C2 and C3 in multiple will discharge sufficient energy through their respective resistors R1, R2 and R3, and through the winding of relay AZR to cause relay AZR to release at the end of a 21 second interval.

When relay AZR releases, signal control relay AXR will immediately release and will close the circuit which energizes signal ZCS.

From the foregoing discussion, it should be clear that a' train going 70 miles per hour will, in traversing the timing section 1T, cause 1TER to pick up and hence cause capacitor C1 to become charged. Upon entering the 3000 foot warning section 2T, the release of the auxiliary relay AZR will be delayed for the time required for the charged capacitor C1 to discharge. A train moving at 70 miles per hour will travel 3000 feet in approximately 29 seconds. In order that trafiic on highway A is given a second warning of the approaching train, relay AZR must release 9 seconds after the train enters section 2T. Therefore, capacitor C1 and resistance R1 are so proportioned that capacitor C1 will discharge through resistance R1 and the winding of relay AZR sutficiently in 9 seconds to cause relay AZR to release. Upon relay AZR releasing, relay AXR will release and signal 2C8 will become energized.

A train traveling at 61 miles per hour will not stay in the timing section 1T long enough to cause relay ZTER to pick up, since relay ZTER will pick up only when a train moves through section IT at 60 miles per hour or less. Therefore, the only time element relay which will pick up when a train travels through section 21 at 61 miles per hour is relay ITER, and this relay picking up will close a snubbing circuit across the winding of relay AZR including capacitor C1 which will delay the release of relay AZR for 9 seconds after a train enters section 2T. However, a train traveling at 61 miles an hour will travel 3000 feet in approximately 34 seconds. Therefore, traffic on highway A will get a second warning of the approaching train which will be altogether satisfactory.

Timing unit U2 is constructed similarly to timing unit U1 and it provides a time delay in addition to the time delay provided by the timing unit U1. The additional time delay is necessary to provide a warning time at highway B in the desired range of 20 to seconds. Assuming that highway B is 1000 feet from highway A, that is, track section 3T is 1000 feet long, a train traveling at 50 miles per hour would traverse 1000 feet in approximately 13.6 seconds.

As was already described, a train which travels over section IT at 50 miles per hour will cause time element relays lTER, ZTER and 3TER to pick up. With relays ITER, 2TER and BTER picked up, in addition to snubbing circuits including snubbing capacitors C1, C2 and C3 being established across the winding of relay AZR, snubbing circuits including capacitors C8, C9 and C10 will be established across the winding of relay BZR by the closing of front contact 0 of each of the relays ITER, ZTER and BTER. The purpose of this will become clear presently. In addition to the snubbing circuits including capacitors C8 to C10 being connected across the winding of relay BZR, a continuously closed snubbing circuit is also across the winding of relay BZR. The purpose of this snubbing circuit will become clear as this description proceeds. Upon entering section 2T, relays ZTR and 2-3TPR will release and capacitors C1, C2 and C3 will commence discharging through the winding of relay AZR. At this instant relay AXR is energized by the circuit which was previously traced from the positive terminal 13 of battery LB, over front contact d of relay battery LB over a previously traced circuit including front contact b of relay 3TR and front contact b of relay AXR. Now, upon capacitors C1, C2 and C3 discharging sufiiciently to cause relay AZR to release, which should occur approximately 21 seconds after the train enters section 2T, relay AXR will release. When relay AXR releases, the normal energizing circuit for relay BZR will become opened at front contact b of relay AXR. However, relay BZR will not immediately release because it is kept picked up by the energy stored in the snubhing capacitors C7 to C10.

As was pointed out earlier, highway'crossing signal 3C8 should be energized approximately 13.6 seconds after signal 2C8 is energized if a train is moving along the stretch of track at miles per hour. Therefore, relay BZR should release 13.6 seconds after relay AXR. in order to accomplish this 13.6 seconds delay, capacitors C7, C8, C9 and C10 are proportioned so that they will discharge through their respective resistors R7, R8, R9 and R10, and the Winding of relay BZR sufiiciently to cause relay BZR to release in 13.6 seconds. Upon relay BZR releasing, relay BXR will immediately release which in turn will cause signal 3CS to be energized and the time of energization of signal 3CS will be approximately 13.6 seconds after signal ZCS is energized.

One distinction between timing unit U1 and timing unit U2 is that timing unit U2 is provided with capacitor C7 which it directly connected across the terminals of relay BZR as contrasted with snubbing capacitors C8 to C13 which are only connected across the winding of relay BZR when time element relays ITER to 6TER, respectively, are picked up. CapacitorC7 provides a time delay before signal 3CS becomes energized even if signal ZCS is energized immediately upon an approaching train. entering section 2T, that is, even if the train is traveling faster than miles per hour, in which case none of the time element relays would be picked up. For instance, if a train travels miles per hour down the stretch of track, none of the time element relays would pick up while the train occupies section 1T. Upon entering section 2T, relay 2TR would release causing relay 2-3TPR to release which in turn will cause relay AZR to release immediately since its winding will not have a snubbing circuit across it. Upon relay AZR releasing, relay AXR will release thus causing signal ZCS to commence operating and opening the circuit energizing relay BZR. Relay BZR will not yet release, however, because capacitor C7 is charged and connected across its winding.

Capacitor C7 is so proportioned that it will discharge through resistor R7 and the winding of relay BZR in a. period of time which will provide the traflic on highway B a safe warning time if the train is moving at maximum authorized speed. Assuming that the maximum authorized speed is 80 miles per hour, then the train will travel from the entrance of section 2T to highway B in 34 seconds. If capacitor C7 is proportioned to discharge in 9 seconds, trafiic on highway B will receive a warning of the approach of the train 25 seconds before the train reaches the crossing, which is a safe warning time. It should be clear that if section ST is relatively shorter the maximum authorized speed for trains traveling on the stretch is relatively high, capacitor C7 can be dispensed with without danger of unduly long Warnings being given to trafiic on highway B.

When the'train enters section 3T, relay 3TR will release because it is now shunted by the wheels and axles of the train. With relay STR released, the energizing circuit for relay 23-T PR will be open at front contact a of relay STR. When the train vacates section 2T, relay 2TR will pick up but relay 2-3TPR will 'stay released and stick relay CKSR will remain picked up by the previously traced second stick circuit. Also occurring when 9 relay 2TR picks up will be the reenergization of relay AXR which will also pick up, and thereby deenergize signal 2C8. With relay 3TR released, the circuit which normally energizes relay BZR will be open and relay BZR will release. Accordingly, relay BXR will release and close the circuit for energizing signal SCS.

When the train vacates section 3T, relay 3TR will pick up thus closing its front contact b and reestablishing the circuit for energizing relay BZR which will immediately pick up. With relay BZR picked up, relay BXR will pick up due to its receiving energy from battery LB over a previously traced energizing circuit. Also, when relay 3TR picks up, the circuit for energizing relay 2-3TPR is reestablished, causing it to pick up. When relay 2-3TPR picks up, the previously traced second stick circuit which energized relay CKSR will become opened at back contact b of relay 2-3TPR, thus causing relay CKSR to release. With relay CKSR released, the circuits energizing the clutch magnet G of each of the time element relays lTER to 6TER will be interrupted and each of the arms 16 of those relays will be returned to its normal position, thus opening the timing contacts b and c of the time element relays which have picked up and closing the contacts a' and all of the checking contacts a in a manner already described. When relay 2-3TPR picks up, its front contact is once more closed thus reenergizing relay AZR and causing it to pick up. Thus the entire circuit arrangement is reset for its next operation.

It should be pointed out that because the capacitors in the timing unit-s are connected across the winding of the auxiliary relay only after the time element relays pick up, if, for some reason, a time element relay should fail to become energized upon a train or vehicle entering the timing section 1T, the associated capacitor will not be connected across the winding of the auxiliary relay. With less capacitance across the auxiliary relay than there should be under the given conditions, the auxiliary relay 7 will release prematurely. This will cause the signal control relay to release sooner than it should, in view of the train speed, and highway traflic to receive a prolonged warning period. However, this prolonged period is on the safe side.

If, for some reason, one or more of the time element relays fail to release after operating, it is possible that on the following operation more snubbing capacitance would be provided across the terminals of relays AZR and BZR than there should safely be in view of the speed of the following train. This may result in an unduly long time delay before each of the highway crossing signals 2C8 and 3C5 will be energized. Hence trafiic on highways A and B may not receive ample warning of the approach of a train.

In order to avoid this situation, the stick relay CKSR is originally energized over the previously traced circuit including the checking contact a of each of the time element relays lTER to 6TER. If one or more of these relays fail to release after an operation, the stick relay cannot pick up on a subsequent operation. With relay CKSR released, none of the clutch magnets G of relays lTER to 6TER will operate and none of the time element relays will pick up during the subsequent operation. Moreover, as the following train enters section 2T and relay 2TR releases, relay AXR will immediately release since each of the previously traced multiple circuit paths for energizing relay AXR will be open. Thus signal ZCS will be energized immediately upon the following train entering section 2T. There will be no time delay, which is on the safe side. Furthermore, upon relay AXR releasing, relay BXR will also release because neither of its multiple energizing circuits will be closed. Thus signal SCS will also be energized immediately upon the following train entering section 2T, which again is on the safe side.

Although we have herein shown and described a graduated time control system embodying our invention 'which controls two relatively closely spaced highway crossing signals, our system will operate equally as well in the control of one crossing signal or of more than two closely spaced crossing signals. In controlling the signal at only one crossing, the repeater relay 2-3TPR may be omitted and track relay ZTR can be employed to perform those functions performed by relay 2-3TPR which are necessary for controlling only one crossing signal.

Although we have herein shown and described only one form of graduated time'control system embodying our invention, it will 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 our invention.

Having thus described our invention, what we claim is:

I. A graduated time control system for protecting a highway crossing comprising a stretch of railway track divided into a first and a second track section, a highway crossing signal adjacent said highway crossing, a control relay for controlling said highway crossing signal, a plurality of normally deenergized time element relays having different operating times and arranged to pick up sequentially, a plurality of capacitors one associated with each of said time element relays, means actuated by the presence of a train in said first track section for energizing all of said time element relays in multiple, and means controlled by the picking up of each time element relay for connecting the associated capacitor in multiple with said control relay for delaying the operation of said highway crossing signal after the train enters said second section an amount of time dependent upon the speed of said train.

2. In a graduated time control system for protecting a point along a stretch of railway track where a highway intersects said stretch, said stretch being divided into a first and a second track section by insulated joints, a highway crossing signal adjacent said intersection, a control relay for controlling said highway crossing signal, a plurality of normally deenergized time element relays having different operating times and arranged to pick up sequentially, a plurality of capacitors, means actuated by the presence of a. train in said first section for energizing all of said time element relays in multiple, and means controlled by the picking up of a predetermined number of said time element relays for connecting a number of said capacitors dependent upon the speed of the train in multiple with said control relay for delaying the operation of said crossing signal after said train enters said second section an amount of time dependent upon the speed of said train.

3. A graduated time control system comprising a. stretch of railway track divided into a first and second section by insulated joints, each section provided with a track circuit including a track relay, a highway crossing said second section, a crossing signal adjacent said highway crossing, a control relay for controlling said crossing signal, a plurality of normally deenergized time element relays having different operating times and arranged to pick up sequentially, a plurality of capacitors, one of said capacitors associated with each of said time element relays, means for energizing all of said time element relays in multiple upon the track relay associated with said first section becoming deenergized, and means including the picking up of a time element relay for com necting its associated capacitor in multiple with said control relay for delaying the operation of said crossing signal after a train enters said second section an amount of time dependent upon train speed.

4. In combination, a stretch. of railway track divided into a first and a second track section by insulated joints, said first section being of a predetermined length for measuring the speed of a train, said second section being intersected by a highway at the end remote from said first section, each of said track sections being provided with a track circuit including a track relay, a highway crossing signal adjacent said intersection, asignal control relay controlling said highway crossing signal, an

gized, said time element relays each further including a timing contact which becomes closed at the expiration of a predetermined time interval after said first and second magnets become energized and which subsequently remains closed as long as said first magnet remains ener- 'gizd, said time element relays each being'providedwith 'means for deenergizing said second magnet following the closing of said timing contact, said time element relays having different op'era'ti'ngtimes and being arranged to close their timing contacts sequentially, an energizing circuit for said stick relay closed only when said track relay'associated with said first track section is deenergized and all of said checking contacts are closed and said second track relay is energized, a first stick circuit for said stick relay closed onlywhen said first track relay is deenergized and said second track relay is energized, a second stick circuit for said stickrelay closed only when said second track relay is deenergized, a first circuit for energizing said signal control relay closed when said second track relay is energized, a second energizing circuit for said signalcontrol relay closed when said auxiliary relay is energized and said'stick relay is energized, an energizing circuit for said auxiliary relay closed when said second track relay is energized, a plurality of capacitors, one associated with one each of said time element relays, a plurality of circuits for charging said capacitors each closed when said second track relay is energized and said timing contact of said associated time element relay is closed, and a plurality of snubbing circuits for delaying the release of said auxiliary relay each including one'of said capacitors and closed when said timing contact of said associated time element relay is closed.

5. in combination, a stretch of railway track divided into two adjacent track sections by insulated joints, each of said track sections having a track circuit including a track relay, a first of said track sections being in approach to a second of said track sections, said second track section being intersected by a highway at the end remote from said first section, a highway crossing signal adjacent said. intersection, a control relay, circuit means for energizing said signal controlled by a back contact of said control relay, a slow release stick relay, an aux- Cit iliary relay, a first circuit means for energizing said conftrol I relay controlled by a front contact of said stick relay and affront contact of said auxiliary relay, a second circuit means for energizing said control relay controlled by a front contact of the track relay associated with said second track section, circuit means for energizing said auxiliary relay controlied by a front contact of said track relay associated with said second track section, a code transmitter including a contact periodically operated at a predetermined rate, a plurality of time element relays, each time element relay including a first magnet controlled by a front contact of said stick relay and a second magnet energized each time said contact of said code transmitter becomes closed when a front contact of said second track relay is closed, said time element relays each including a. checking contact which becomes opened immediately upon said first and second magnets both be coming energized, each time element relay further including a timing contact arranged to close at the expiration of a predetermined time interval after said first and second magnets become energized and remain closed so long as said first magnet remains energized, and means fo deenergizing said second magnet after said timing contact is closed, said time element relays having difierent operating times andbeing arranged to close their timing contacts sequentially, a circuit means for energizing said stick relay controlled by a back contact of the track relay associated with said first track section and the checking contact of each of said time element relays and a front contact of said second track relay, a first stick circuit means for energizing said stick reray controlled by a back contact of said first track relay and a front contact of said second track relay, a second stick circuit means for energizing said stick relay controlled by a back contact of said second track relay, a plurality of capacitors, one of said plurality of capacitors associated with one each of said time element relays, a plurality of circuit means for charging said capacitors each controlled by a front contact of said second track relay and the timing contact of an associated time element relay, and a plurality of snubbing circuits for relaying the release of said auxiliary relay each including one of said capacitors and controlled by said timing contact of said associated time element relay.

References Cited in the file of this patent UNITED STATES PATENTS Young et al. Feb. 7, 1933 Jacobs et a1 Nov. 18, 1952

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