US2231520A

US2231520A - Railway signaling apparatus

Info

Publication number: US2231520A
Application number: US313117A
Authority: US
Inventors: Paul H Crago
Original assignee: Union Switch and Signal Inc
Current assignee: Hitachi Rail STS USA Inc
Priority date: 1940-01-09
Filing date: 1940-01-09
Publication date: 1941-02-11
Anticipated expiration: 1958-02-11

Description

Feb. 11, 1941.

P. H. cRAG RAILWAY SIGNALING APPARATUS 3 Sheets-Sheet 1 Filed Jan. 9, .1940

lllllllllllL INVENTOR Pa .Cz ajo HAS A T'roRNEY Feb. 11, 1941. P. H. CRAGO 2,231,520

RAILWAY SIGNALING APPARATUS Filed Jan. 9, 1940 3 Sheets-Sheet 2 Craga INVENTOR HA5 A'TTORNEY i.|llllll Ill 1% 06 98% Q QN QUE,

Patented Feb. 11, 1941 UNITED STATES PATENT OFFIQ RAILWAY SIGNALING APPARATUS Application January 9, 1940, Serial No. 313,117

16 Claims.

My invention relates to railway signaling apparatus, and moreparticularly to apparatus for control of electric motors used in railway signaling.

In railway signaling a traffic controlling device is provided usually with a mechanism which includes an electric motor for moving such traflic .controlling device from one position to another. Such traffic controlling device often becomes obstructed with the result that the motor becomes overloaded. To protect the motor and the associated mechanism and to avoid an unnecessary output from the current source which may be a battery, it is necessary to interrupt the motor operating circuit automatically under overload conditions when such device .is automatically controlled. .It is often the case that the obstruction in the movement of such traflic controlling device is only temporary so that if a second or later attempt be made to operate the motor shortly after the motor operating circuit has been interrupted due to an overload condition, the desired movement of the device is accomplished in the usual manner. Also such obstruction may be caused by ice or sleet which is broken up when a few repeated attempts are made to move the device.

Accordingly, a feature of my present invention is the provision of novel and improved apparatus 113 for automatically interrupting a motor operating circuit under overload conditions, and wherewith the motor operating circuit is automatically closed at predetermined intervals so that repeated attempts are made to move the associated device as long as the obstruction which causes the overload condition continues to exist. Another feature of my invention is the provision of novel and improved apparatus of the type here contemplated wherein control apparatus common to a plurality of dififerent trafiic controlling devices each operated by an individual motor efiects overload protection for any motor on which an overload may occur and at the same time permits the remaining motors on which no overload exists to complete their respective movements. The above features as well as otherobjects and advantages of apparatus embodying my invention I obtain by providing a slow-acting relay and a time element relay or overload device, there being an overload device for each motor to be protected with a single slow-acting relay common to several motors or there may be a slow-acting relay for each motor. The time element relay or overload device is set for a preselected operation period or when an overload has persisted for a time determined by the degree of the overload and is energized over a circuit including a contact of the control element and a contact of the mechanism which the motor is to actuate. This mechanism contact is closed when the traffic controlling device actuated thereby occupies its stop or a preselected position and is opened when the traific controlling device is moved a short or preselected portion of its movement away from such position. Hence when the control element is set to close the motor operating circuit the circuit for energizing the overload device is also closed and the overload device is operated if an obstruction prevents the motor from actuating the mechanism to move the trafiic controlling device away from the stop position before the operation period of the overload device has elapsed. If the overload device is operated the slow acting relay is energized to interrupt the motor circuit and to also reset the overload device. At the end of the preselected delay period of the slow-acting relay the motor operating circuit is reclosed to make a second attempt to actuate the associated mechanism. If the obstruction still persists then the overload device again functions at the end of its operation period to again energize the slow-acting relay which in turn interrupts he overloaded motor circuit and resets the-overload device. This cycle of events is automatically repeated as long as the obstruction is present or until the position of the control element is changed by some outside condition. Contacts operated by each traflic controlling device, when actuated a given portion of its movement away from the stop or preselected position, complete a stick circuit which removes the associated motor from the control of the slow-acting relay and hence operation of this motor is unaffected if an overload on a second motor causes energization of the slowacting relay.

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

In the accompanying drawings, Fig. 1 is 2. diagrammatic view showing one form of apparatus embodying my invention when used with highway crossing gates. Fig. 2 is a diagrammatic view showing a modification of the apparatus of Fig. 1 also embodying the invention. Fig. 3 is a diagrammatic view showing a different form of apparatus embodying my invention when used with highway crossing gates. Fig. 4 is a. chart showing the sequence of operation of certain circuit controlling contacts of the gate mechanism of Figs. 1, 2 and 3. In each of the several views like reference characters designate similar parts.

It will be understood, of course, that my invention is not limited to apparatus for controlling highway crossing gates but this one use serves to illustrate the many places where apparatus embodying my invention is useful.

Referring to Fig. 1, the reference characters Ia and lb designate the track rails of a railway intersected at grade by a highway H and at which intersection highway crossing gates GI and G2 are located. The track rails Ia and lb are formed by the usual insulated rail joints with two track sections, one on each side of the highway, a section D--E being formed on the left of highway H as viewed in Fig. 1 and a section E F being formed to the right of the highway. Each track section is provided with a track circuit which includes a current source such as a battery I0 connected across the rails at one end of the section and a Winding of an interlocking relay IR. connected across the rails at the other end of the section, a winding I I of relay IR being thus associated with section DE and a winding I2 of relay IR being associated with section E-F. The connections of windings I I and I2 with the track rails are those of common practice to provide the so-called extended shunt protection as will be readily understood by an inspection of Fig. 1 and these connections need not be described in detail as they form no part of my invention.

The highway crossing gates GI and G2 are located one on each side of the railway and the gates are disposed for their respective gate arms I3 and I4 to be operated between a lowered position where the arms extend horizontally. across at least a portion of the highway to obstruct highway traific approaching the intersection, and. a raised position where the arms extend substantially vertical to clear highway trafilc. The

, crossing gates GI and G2 are provided preferably with similar operating mechanisms which maybe of any one of several well-known types. In the present embodiment of the invention the mechanism for each crossing gate is similar to that shown and described in Letters Patent of the United States No. 1,138,087 granted to John P. Coleman on May 4, 1915, for Railway signals, the gate arm being an extended form of. the semaphore of the patent. Inasmuch'as the specific structure of the gate mechanism forms no part of my invention, it will be described only insofar as to provide a full understanding of my invention. Looking at the gate GI mechanism of Fig. 1, the essential elements comprise a motor MI, a slot magnet SMI and a circuit controller designated as a whole by the reference C I. The motor MI includes an armature I5 and a field winding I6 and is connected by suitable means, not shown, with the gate arm I3 of gate GI. The gate arm I3 is biased by gravity to its lowered or obstructing position and the motor M-I when energized raises the arm I3 against the biasing force to its raised or clear position, the full movement of the arm being approximately 90. In the following description the obstruct ingposition will be referred to as the 0 position and the clear position will be referred to as the 90 position- The slot magnet SMI includes a high resistance winding I1 and a low resistance winding I8, winding I! being energized to hold the arm I3 at its clear position after the motor is deenergized, and

winding I8 being connected in series with the The circuit controller CI is operatively connected with the mechanism for operating a series of contacts designated by the

numerals

2, 3, 4, 5 and 8, and which contacts are operated at different points between the 0 and the 90 positions.

These contacts of controller CI are shown conventionally and the sequence in which they are opened and closed is set forth in the chart of Fig. 4.

The gate G2 mechanism of Fig. 1 is preferably the same as the mechanism for gate GI, and

includes a motor M2, a slot magnet SM2 and a circuit controller C2.

The immediate control of the motors MI and M2 is effected by two control relays IWR and 2WR. When control relay IWR. is energized to close front contact I9, a motor operating circuit can be traced from terminal B of a suitable source of current such as a battery not shown over front contact I9 of relay IWR, wire 20, No. 8 contact of circuit controller CI when closed, armature I5 and field winding I6 of motor MI, low resistance winding I8 of slot magnet SMI and to terminal C of the same source of current. Similarly, control relay 2WR controls a motor operating circuit extending from terminal B of the current source over front contact 2| of relay 2WR, wire 22, No. 8 contact of circuit controller C2, armature 23 and field winding 24 of motor M2, low resistance winding 25 of the associated slot magnet SM2 and to terminal C.

The gates GI and G2 are automatically controlled by railway traffic conditions of the track sections DE and EF by the slot magnets SMI and SM2 together with the control relays IWR and 2WR being governed in part by the interlocking relay IR. To provide overload protection for the motors MI and M2, two time element relays ITE and 2TE are associated with the operating circuits of motors MI and M2, respectively. To cause the motors MI and M2, when overloaded, to be operated periodically in attempting to raise the respective gate, the apparatus includes a repeated relay XR. and a slow releasing relay TPR, these two relays being common to both gates GI and G2.

As shown in Fig. 1, the time element relays ITE and 2TE are thermal relays, relay ITE being provided with a heater element 26 and two contact fingers 32 and 33 for engaging a front contact 21 and a back contact 28, respectively; and relay ZTE being provided with a heater element 29 and two contact fingers 34 and 35 for engaging a front contact 30 and a back contact 3|, respectively. Looking at relay ITE, when its heater element 26 is effectively energized the two contact fingers 32 and 33 are gradually moved from the position where contact finger 33 engages back contact 28 to a position where the contact finger 32 engages front contact 21, the movement being effected in. a predetermined time interval, such as, ten seconds. When the heater element 26 is deenergized the relay quickly cools and the contact fingers 32 and 33 are moved back to the normal position, that is, the position shown in Fig. 1. In like fashion the contact fingers 34 and 35 of relay 2TE are moved to open back contact 3! and to close front contact 30 when the heater element 29 is effectively energized for a predetermined time interval such as ten seconds, and the contact fingers are quickly moved back to their normal position when the relay is deenergized.

-Repeater relay XR is preferably of the usual acting type but relay TPR is slow releasing in character and is preferably of the type that permits overenergization to provide a release period of relatively long duration, say, for example, a release period of the order of ten seconds. Furthermore, relay TPR is preferably provided with a so-called snubbing circuit by which the winding of the relay is short circuited to aid in prolonging the slow release of the relay.

In Fig. 1, gates G! and G2 are provided with bells Bi and B2, respectively, which are sounded to give a Warning when the gate arms are about to be lowered, such warning being effective until the gate arms have reached the obstructing position. It will be understood, of course, that other warning signals such as the usual flashing red lights may be provided but such additional warning signals are not shown for the sake of simplicity since they would be in accordance with usual practice.

It is believed that the circuits for the different relays and the control affected by these relays can best be understood from a description of the operation of the apparatus, the circuits being traced as they are used. Normally, that is, when both track-sections D-E and E-F are unoccupied and both windings H and I2 of interlocking relay IR. are energized, the repeated relay XR, the slow release relay TPR and control relays lWR and ZWR are energized, but both time element relays HE and ZTE' are deenergized. Also the high resistance windings I1 and 50 of the slot magnets SMI and SM2, respectively, are energized to hold the respective gate arms at the clear position, and both warning bells BI and B2 are silent so that highway traffic over the intersection is unobstructed.

Repeater relay XR. is normally energized over a circuit including terminal B,

front contacts

36 and 31 of interlocking relay IR, winding of relay XR, No. 4 contact of each of the controllers Cl and C2, and terminal C, the No. 4 contact of each controller being closed with the gate arm at the 90 or clear position as indicated by the chart of Fig. l. Slow release relay 'IPR is normally energized over a simple circuit including front contact 33 of repeater relay XR. The circuit for energizing control relay IWR involves terminal B,

front contacts

39 and 40 of interlocking relay IR, wire M, front contact 52 of the No. 5 contact of controller Cl, wire 43, winding of relay IWR, back contact 28-33 of the time element relay I TE and terminal C. The circuit for control relay iiWR is the same as the circuit for relay IWR up to wire 4!, thence over wire 44, front contact 55 of the No. 5 contact of controller C2, wire 46, winding of relay ZWR, back contact 3l-35 of time element relay 2'IE and to terminal 0. To hold gate G! at its clear position, winding H of slot magnet SM l is normally energized by a circuit extending from terminal B either over front contact 47 of relay TPR to Wire 48 or over front contact 69 of control relay lWR and wire 64 to wire 48, and thence to winding ll of magnet SMI and to terminal C. Gate G2 is held at its clear position by winding 50 of slot magnet SMZ being energized over a circuit extending from terminal B either over front contact 5| of relay TPR to wire 52 or from terminal B over front contact 53 of relay ZWR to wire 52, and thence to winding 50 of magnet SM2 and to terminal 0.

Assuming that a train approaches the highway either from the left to enter section D-E or from the right to enter section E-F, either the winding II or the winding I2 of interlocking relay IR is shunted and the armatureof the shunted winding is released to its full down position so that repeater relay XR and the control relays IWR and ZWR are deenergized and immediately released. The release of relay XR. opening front contact 38 deenergizes slow release relay TPR and that relay is released at the end of its slow release period. It should be observed that the release of relay XR closing back contact. 54 completes a so-called snubbing circuit for relay TPR and which circuit extends from terminal over either full down back

contact

55 or 56 of relay IR, back contact c of relay XR, winding of relay TPR and to terminal C. With the release of control relays IWR and ZWR opening the respective

front contacts

49 and 53, one path of each of the energizing circuits for windings H and 50 of the slot magnets SMI and 8M2, respectively, is opened but both of these windings are retained energized during the slow release period of relay TPR, winding I! being energized over the path including front contact 4'! of relay TPR and winding 56 being energized over the circuit path including front contact 5| of relay 'IPR.

With either winding H or E2 of interlocking relay IR released closing back contact 5'! or 58 a circuit is formed for bells Bi and B2 and the bells are sounded to warn highway users of the approach of a train and that the gate arms are about to be lowered. This bell circuit extends from terminal B over either back contact 51 of winding H or over front contact 36 of winding II and back contact 58 of winding 12 to wire 59 and thence over No. 3 contact of controller Cl and bell Bl to terminal C in parallel with No. 3 contact of controller C2 and bell B2. to terminal C.

When slow release relay TPR is released at the end of its slow release period opening front contacts 41 and 5|, both windings l1 and 56 of the slot magnets SlVIi and SM2 are deenergized and the respective gate arms I3 and hi are permitted to drop under the influence of the biasing element of the respective gate mechanism to be obstructing position where the arm extends across the highway to obstruct highway traffic from the intersection.

Looking at the mechanism for gate GI of Fig. 1 it is to be noted that the motor Ml isprovided with a short circuit including a resistor which circuit causes the motor to act as a generator and cushion the dropping of the gate arm l3 as it reaches the lowered position. Such short circuit can be traced from the left-hand terminal of armature l5 through field winding 6, a slot contact 60 of the mechanism closed when the slot magnet is deenergized and the mechanism'"is moved in the direction to lower the gate arm, a resistor M, No. 2 contact controller CI which is opened at the 2 position when the gate is drop ping (see Fig. 4) and back to the right-hand terminal of armature I5. G2 is provided with a similar short circuit for cushioning the dropping of the gate arm [4 and which short circuit for motor M2 need not be traced, these circuits forming no part of my invention. Consequently, gates GI and G2 are at their lowered positions while the train approaches and passes over the highway.

When the train clears the intersection, the winding H or E2 whichever was shunted by the train approaching the intersection is reenergized and picked up, the other winding of the relay being deenergized with its armature held at the interlocked position of the relay as the train recodes from the intersection.- The repeater relay XR is not at once reenergized when its circuit is The motor M2 of gate prepared at

front contact

36 or 31 of relay IR because the No. 4 contact of both controllers CI and G2 which are interposed in the circuit for relay XR are open with the gate arms at the lowered position. Slow release relay TPR also remains deenergized but both control relays IWR and ZWR are at once picked up over circuits including and to terminal C.

With control relay IWR picked up closing front contacts I9 and 49 the operating circuit for motor MI and the energizing circuit for winding II of slot magnet SMI are completed with the result that the motor MI is operated to raise the arm I3 of gate GI. With control relay 2WR picked up closing front contacts 2| and 53 the operating circuit for motor M2 and the energizing circuit for winding 50 of slot magnet SM2 are closed so that motor M2 is operated to raise the arm I4 of the gate G2. With the gate arms unobstructed the associated motors function to raise the respective arm in the usual predetermined time interval which may be of the order of ten to fifteen seconds, the motor circuit in each case being opened at the No. 8 contact of the associated circuit controller when the arm reaches the clear position but the slot magnet remaining energized to hold the arm in the clear position. When both gates are raised so that the N0. 4 contact of both circuit controllers CI and C2 are closed the repeater relay XR is energized and picked up closing front contact 38 which, in turn, causes the relay TPR to be energized and picked up and the apparatus is restored to its normal position.

Assuming that in response to a train approaching the intersection the gates GI and G2 are lowered in the manner described hereinbefore and the train clears the intersection so that I the two control relays IWR and 2WR are picked up to cause the gate mechanism to be operated to raise the gate arms, energizing circuits for each of the time element relays ITE and 2TE are closed. The circuit for time element relay ITE can be traced from terminal B over front contacts 39 and of interlocking relay IR, wire 4|, back contact 65'of the No. 5 contact of controller CI, wire 66, front contact 61 of control relay IWR, heater element 26 of relay ITE and to terminal C. The circuit for relay ZTE is the same up to wire 4| thence over wire 44, back contact 69 of the No. 5 contact of controller C2, wire Ill, front contact II of control relay ZWR, heater element 29 of relay ZTE and to terminal C. The back contacts 65 and 69 of the No. 5 contact of controllers Cl and C2 are adjusted to be opened when a preselected portion of the movement of the gate arm from the lowered position to the raised position is completed. As indicated in the chart of Fig. 4, the back contacts 65 and 69 of the present embodiment of the invention are set to open at 10. When the gates are unobstructed this portion of the movement is completed and the respective back contacts 65 and 69 are opened before the predetermined operation period of the associated time element relay is completed, whichl operation period, I have assumed for the sake of illustration to be ten seconds. Consequently when the gate arm is unobstructed, the heater element of the associated time element relay is deenergized and the relay returned to its normal position before it has completed its movement to close the respective front contact.

Hence, when the gate arm is unobstructed the time element relay performs no useful function. It is to be observed that although the time element relay ITE may be operated enough to open its back contact 2333 during the time it takes to raise the arm I3 of gate GI 10, control relay IWR is retained energized over its front contact M which front contact completes a shunt path around the back contact 28-43 of relay ITE. Likewise, front contact 13 of control relay ZWR, when closed, completes a shunt path around back contact 3I35 of time element relay ZTE.

I shall next assume that both gates GI and G2 have been lowered due to a train approaching the intersection, the train has passed over the intersection so that the control relays IWR and ZWR have been picked up to cause the gates to be raised and one of the gates, say gate GI, is obstructed and not raised away from its lowered position or at least is raised less than 10 in the ten seconds interval of the operation period of relay ITE so that front contact 2'l32 of relay ITE is closed, a circuit is completed for the slow release relay TPR and that relay is picked up. This circuit for energizing relay TPR extends from terminal B over

front contacts

39 and 40 of interlocking relay IR, wire 4|, back contact 65 of the No. 5 contact of controller CI, wire 66, front contact 2l32 of relay ITE, wire 12, winding of relay TPR and to terminal C. With relay TPR picked up opening back contact 62 the control relay IWR is deenergized and released to open at its front contact I9 the overloaded motor circuit and operation of motor MI is stopped. Release of relay IWR opening front contact 61 also removes current from heater element 26 of relay ITE and that relay quickly cools causing its contact fingers 32 and 33 to move back to their normal position, the circuit for energizing relay TPR being opened when contact 2l--32 of relay ITE is opened. Relay TPR remains picked up until the end of its slow release period which I have assumed to be of the order of 10 seconds. Hence the motor operating circuit of motor MI remains open until slow release relay TPR is released to close its back contact 62 and again cause control relay IWR to be picked up. Motor MI is then operated to make a second attempt to raise the gate GI. If the obstruction still persists so that the gate arm is not raised away from its lowered position or at least is not raised the 10 necessary to open back contact 65 of the No. 5 contact of controller CI in the operation period of the time element relay ITE, that relay is operated to again energize the slow release relay TPR which picks up and causes the control relay IWR to be deenergized to interrupt the motor operating circuit and also to remove current from the time element relay ITE. It is clear that as longas the obstruction remains on the gate GI this up opening back contact 63 interposed in the circuit for control relay 2WR because front contact 45 of the No. 5 contact of controller C2 is closed and control relay 2WR is retained energized over a stick circuit. This stick circuit can be traced from terminal B over front contacts 39 and of interlocking relay IR, wires 4| and 44, front contact of the No. 5 contact of controller C2, since front contact 45 is closed when the gate arm I4 is raised a little over 10, wire 46, winding of relay ZWR, front contact I3 of the relay and to terminal C.

If the obstruction is on gate G2, the associated relays 2TE, TPR and 2WR are operated in the manner similar to that described for relays ITE, TPR and IWR when gate GI is obstructed and the description need not be repeated. It should be observed, however, that when gate G2 is obstructed, operation of gate GI is not hindered because control relay IWR is retained energized when relay TPR is picked up by a stick circuit extending from terminal B over

front contacts

39 and 43 of relay IR, wire 4I, front contact 42 of the No. 5 contact of controller 01, wire 43, winding of relay IWR, front contact I4 of that relay and to terminal C. 7

From the foregoing description it is apparent that if gates GI and G2 are both obstructed the apparatus functions to protect both motors MI and M2 and to make repeated attempts to raise the gates.

It is clear, therefore, that the apparatus of Fig. 1 provides automatic control for the highway crossing gates GI and G2 with protection to motors MI and M2 against overload conditions if the associated gate arm is obstructed at its lowered position. Also if a gate arm is obstructed, the associated motor is periodically energized to attempt to raise the gate arm.

Referring to Fig. 2, highway crossing gates GI and G2 are located at the intersection of a railway and highway H the same as in Fig. l, the track rails of the railway being formed into track-circuited sections DE and E-F. Also'the apparatus for controlling the gatesGI and G2 is substantially the same as in Fig. 1, except the repeater relay XR is replaced by a slow release repeater relay TP, the Warning bells BI and B2 are not shown, and the circuits are arranged differently.

Under the normal condition of the apparatus of Fig. 2, that is, when track sections DE and E-F are unoccupied and both windings II and I2 of interlocking relay IR are picked up, the repeater relay '1? is energized but the remaining relays TPR, IWR, ZWR, ITE and ZTE are deenergized. Windings I! and of slot magnets SMI and SM2 are both energized to hold the gates at their clear position. The circuit for the repeater relay '1? includes front contacts 33 and 31 of the interlocking relay as will be readily understood by an inspection of Fig. 2. The windings I1 and 50 are energized in parallel over a circuit which has three alternative connections with the B terminal of the current source, one of which connections includes front contacts I5 and I3 of interlocking relay IR, the second of which connections includes front contact ll of repeater relay TP and the third of which connections includes front contact E8 of relay TPR when that relay is picked up in a manner to shortly appear.

When a train approaching the highway enters either track section DE or E-F shuntingeither winding II or I2 of interlocking relay IR and the armature of the shuntedwinding is released, the

circuit for relay is opened at either front con- -minal B over either back contact 51 of winding II or over front contact 36 of winding II and back contact 58 of winding I2, front contact 19 of relay 'IP, winding of relay TPR and to terminal C, and relay TPR is picked up to close at its front contact '18 the connection for the energizing circuit of windings I1 and 5B of the slot magnets. When relay T? is released opening front contact I9, relay TPR, is deenergized and released at the end of its slow release period opening front contact l8 whereupon windings I1 and 50 of the slot magnets are deenergized permitting the gate arms I3 and I4 to drop to their obstructing position. It is clear that when a train approaching the highway intersection enters track section DE or E-F the lowering of the gate arms is not initiated until the end of a period equal to the sum of the slow release periods of relays TP and TPR,. Consequently, any desired warning signals, such as the bells BI and B2 of Fig. 1 or the usual flashing light signals, can be operated during this delay period of the lowering of the gate arms by a circuit similar to that shown in Fig. 1 to warn highway users of the approach of a train and that the gates are about to be lowered. With the gates lowered the highway trafic approaching the intersection is obstructed until the train clears the intersection at which time the winding of relay IR first shunted is reenergized and the armature, of the other winding is held at the interlocked position as the train recedes from the intersection so that windings I1 and. 50 of the slot magnets are reenergized, repeater relay TP is reenergized and picked up and circuits are completed for the control relays IWR and ZWR. Starting from terminal B the circuit for relay IWR involves back contact 80 of relay TPR,

front contacts

40 and 39 of interlocking relay IR, wire 8|, back contact 28-33 of time element ITE, winding of relay IWR, No. 8 contact of controller CI and. terminal C. The circuits for relay ZWR is similar and involves terminal B, back contact 82 of relay TPR,

front contacts

83 and 84 of relay IR, wire. 85, back contact 3I35 of time element relay ZTE, winding of relay ZWR, No. 8 contact of controller C2 and terminal C. Control relay IWR on picking up closes front contact I9 and completes the motor operating circuit for motor MI so that motor MI is operated to raise the gate arm I3 of gate GI, the motor operating circuit being substantially the same as described for Fig. 1. Also control rel'ay ZWR on picking up closing front contact 26 completes the motor operating circuit for motor M2 and motor M2 is operated to raise arm Id of gate G2, this motor operating circuit being also substantially the same as in Fig. l.

With neither gate GI nor G2 obstructed each motor MI and M2 is operated to raise the associatedarm to its clear position where the motor I operating circuit is opened at the No. 8 contact of the respective circuit controller. When the No. 8 contact of controller CI or C2, as the case may be, is opened the circuit of the associated control relay is opened and that relay is deenergized and released to its normal position. It is to be observed that with either control relay IWR or ZWR picked up to cause operation of the respective motor, a circuit is formed for the associated time element relay. The circuit for the time element relay ITE involves terminal B, front contact I9 of relay IWR, wire 20, back contact 65 of No. 5 contact of controller CI, heater element 26 of relay ITE and terminal C; and the circuit for relay 2TE involves terminal B, front contact 2I of relay ZWR, wire 22, back contact 69 No. 5 contact of controller C2, heater element 29 of relay 2TE and terminal G. Since back contacts 65 and 69 of the No. 5 contact of the controllers CI and C2 are opened when the respective gate arm has been raised 10 from the lowered position, the circuits for the time element relays ITE and 2TE are opened and the relays deenergized before the end of their predetermined operation period when the gate arms are unobstructed.

Assuming, however that a train has cleared the intersection and control relays IWR and ZWR have been picked up to cause operation of the motors MI and M2, and the gate GI is obstructed so that its arm i3 is not raised away from the lowered position or at least is raised less than 10 before the time element relay ITE is operated closing its front contact 21-32, the slow release relay TPR is energized and picked up. It is to be noted'that the opening of back contact 28-33 'of relay ITE does not cause release of control relay IWR because relay IWR upon picking up closes its front contact 14 and completes the shunt path around back contact 28-33. The closin of front contact 21-32 of relay ITE completes the circuit for relay TPR which extends from terminal B over front contact I9 of relay IWR, wire 20, back contact 35 of the No. 5 contact of controller CI, front contact 21-32 of relay ITE, front contact 19 of relay TP, winding of relay TPR and to terminal C. With relay TPR picked up opening back contact the relay IWR is deenergized and released interrupting both the operating circuit for motor MI and the energizing circuit for the time element relay ITE. Relay ITE quickly cools causing its contact fingers 32 and 33 to move back into their normal positions. The opening of front contact 21-32 of relay ITE deenergizes slow release relay TPR and that relay is released at the end of its slow release period. Release of relay TPR to close back contact 80 causes control relay IWR to be again picked up to complete the motor operating circuit for motor MI and to complete the energizing circuit for time element relay ITE. Hence a second attempt is made to raise the arm I3 of gate GI against the obstruction. If the obstruction persists, then time element relay ITE operates at the end of its operation period to again cause relay TPR to be energized and bring about an interruption of the motor operating circuit. Consequently, as long as the obstruction persists this cycle of operation of the relays is repeated to make periodic attempts to raise the gate arm.

It is to be observed that when relay TPR is picked up because of the obstruction of gate GI, the opening of back-contact 82 interposed in the control circuit for relay 2WR does not cause that relay to be released and interrupt the clearing of gate G2 because control relay 2WR is retained energized by a stick circuit extending from terminal B over front contact 45 of the No. 5 contact of controller C2,

front contacts

83 and 84 of interlocking relay IR, front contact 13 of relay ZWR, winding of relay ZWR, No. 8 contact of controller C2 and to terminal C.

In the event gate G2 is obstructed and not gate GI- the operation of the apparatus is similar to that described in connection with gate GI obstructed, except time element relay 2TE functions to control the slow release relay TPR and in turn control relay 2WR to interrupt the operating circuit for motor H2. Likewise if both gates are obstructed the apparatus functions to protect both motors and make repeated attempts to raise the gates.

Referring to Fig. 3, gates GI and G2 are located at the intersection of highway H with a railway which has its rails formed with track sections D-E and E-F the same as in Fig. 1. Also the track circuits for sections D-E and E-F include windings II and I2, respectively, of the interlocking relay IR. In Fig. 3, the gate GI mechanism which is the same as in Figs. 1 and 2 is controlled by a slow release repeater relay TP. In this form of the invention overload protection is effected by means of an overload relay OR and operation of the gate mechanism is automatically repeated at intervals when the gate arm is obstructed by means of slow release relay TPR. Furthermore, in this form of the invention each gate GI and G2 is associated with a repeater relay TP, an overload relay OR and a slow release relay TPR. Hence only the relays and the circuits controlled thereby for the gate GI are shown for the sake of simplicity since the corresponding apparatus of gate G2 is but a duplication of that provided for gate GI.

The overload relay OR is a two-winding relay, the top winding 68 of which is connected across a resistor RI interposed in the motor operating circuit to be later referred to. Resistor RI is preferably constructed of material having a positive temperature coefiicient and the parts are so proportioned that the motor current flowing in resistor RI and winding 68 in parallel when the gate is unobstructed is not sufficient to cause relay OR to be effectively energized and picked up but when the gate is obstructed the overload current flowing in resistor RI heats up that resistance so that after an interval the voltage drop across resistor RI raises to a point where the current shunted through winding 68 efiectively energizes relay OR and that relay is picked up, the interval required for relay OR to pick up depending in part upon the degree of the overload.

Normally, that is when track sections D-E and E-F are unoccupied both windings II and I2 of interlocking relay IR are energized, the repeater relay TP is picked up and winding I1 of slot magnet SMI is energized to hold the gate at its clear position. The circuit for relay TP includes terminal B,

front contacts

36 and 31 of relay IR, winding of relay TP, back contact 86 and transfer contact 81 of a continuity transfer contact of relay OR and terminal C. The energizing circuit for winding I1 of slot magnet SMI includes terminal B, front contact 88 of relay TP, wire 89, winding I1 and terminal C.

When a train approaches the intersection of Fig. 3 to enter either section D-E or E-F shunting either winding I I or I2, repeater relay TP is deenergized and released at the end of its slow release period. During the release period of relay TP, relay TPR is energized and picked up over a circuit including terminal B, either back contact 51 of winding II or front contact 36 of winding II and back contact 58 of winding I2, winding of relay TPR, front contact 19 of relay TP and terminal C. When relay TP is released opening front contact 19, relay TPR is deenergized and released at the end of its slow release period. It is to beobserved that after relay T1 is released opening front contact 88, the winding ll of slot magnet SMI is retained energized over a circuit completed at front contact 9B of relay TPR during the slow release period of that relay. Hence the lowerin of arm I3 of gate GI is delayed for a period equal to the sum of the release periods of relays TP and TPR and any desired warning signals such as bells BI and B2 of Fig. 1 may be operated during the delay period to warn highway users that the gates are about to be lowered. When winding I1 is deenergized subsequent to the release of relay TPR, the arm l3 drops to its lowered position obstructing highway traffic from the intersection. When the train clears the intersection relay '1? is reenergized and picked up when the first shunted, winding of the interlocking relay is reenergized. Relay TP when picked up closes at its front contact 9| the motor operating circuit for raising the gate. This motor operating circuit involves terminal B, front contact 9| of relay TP, resistor RI and Winding 68 of relay OR in parallel, armature l5 and field winding iii of motor Ml, low resistance winding l8 of slot magnet SMI, No. 8 contact of controller Cl and terminal C.

I shall next assume that when motor MI is operated to raise gate arm l3, the gate arm is obstructed and an overload current flows in the motor operating circuit, overload relay OR is effectively energized and picked up after a predetermined time interval so that the repeater relay TP is deenergized to interrupt the motor operating circuit. It is to be noted that the picking up of relay OR is further delayed by its winding 94 being short circuited at back contact 92-91. The picking up of overload relay OR to bring about an interruption of the motor operating circuit also completes a stick circuit by which relay OR is retained energized subsequent to the interruption of the motor operating circuit. This stick circuit for relay OR includes terminal B, front contact 88 of relay TP, lower winding 95 of relay OR, resistor t5, front contact 96 and transfer contact 81 of relay OR and terminal 0. It is to be observed that when relay OR picks up and before repeater relay TP is released, the relay TPR is energized by current flowing from terminal B over front contact 85 of relay TP, transfer contact 92 and front contact 93 of a continuity transfer contact of relay OR, winding of relay TPR, front contact 79 of relay TP and to terminal C. When relay TP is released opening

front contacts

19 and 88 relay TPR is deenergized and released at the end of its slow release period. During the release period of relay TPR. the stick circuit for relay OR is closed at front contact 90 of relay TPR. Consequently the overload relay OR is retained energized over its stick circuit for a period equal to the sum of the slow release periods of relays TP and TPR. When relay TPR is released opening front contact 90, overload relay OR is in turn released to close back contact 86 interposed in the circuit for relay TP with the result that relay TP is again picked up to close the motor operating circuit so that the motor is operated to again attempt to raise the gate arm. If the obstruction is not removed, the overload relay OR is again operated to cause relay TP to be released to interrupt the motor circuit.

t is clear that with the apparatus of Fig. 3 the relays TP and TPR are operated to protect motor Ml and to periodically bring about operation of motor Mi to raise the gate arm 13.

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

Having thus described my invention what I claim is:

1. In combination, a signal mechanism biased to a stop position and provided with a motor to move the signal mechanism to a clear position, a circuit controller operatively connected with said mechanism, a control device operative at times to cl;se contacts, a motor operating circuit including a contact of the control device and a contact of said circuit controller opened only when the mechanism is at the clear position to operate said motor to move the mechanism, an overload device having a normally open contact which becomes closed after the device has been energized for a predetermined time interval, a circuit including a contact of said control device and a contact of said circuit controller closed when the mechanism is at the stop position only to energize said overload device, and means including said contact of the overload device to operate said control device as required to interrupt said motor operating circuit when the mechanism is obstructed at its stop position for said predetermined time interval.

2. In combination, a signal mechanism biased to a stop position and provided with a motor to move the signal mechanism to a clear position, a circuit controller operatively connected with said mechanism, a control device operative at times to close contacts, a motor operating circuit including a contact of the control device and a con tact of said circuit controller opened only when the mechanism is at the clear position to operate said motor to move the mechanism, an overload device having a normally open contact which becomes closed after the device has been energized for a predetermined time interval, a circuit including a contact of said control device and a contact of said circuit controller closed when the mechanism is at the stop position only to energize said overload device, a slow release relay, circuit means including said contact of the overload device to energize said slow release relay, and means controlled by said slow release relay when picked up to govern said control device as required to interrupt said motor operating circuit and to deenergize said overload device, whereby said slow release relay is released at the end of its slow release period to govern said control device as required to reclose said motor operating circuit to cause the motor to again attempt to move the signal mechanism from the stop position.

3. In combination, a signal provided with a motor to move the signal from a first to a second position, a circuit controller operatively connected with said signal, an electroesponsive control device operative when energized to close a contact, a moor operating circuit including said contact of the control device and a contact of said circuit controller opened only at said second position to operate the motor, an overload device having a control element and a normalfly open contact which becomes closed after the control element has been effectively energized for a predetermined time interval and which control element is associated with said signal for effective energization thereof when the motor is operated with the signal obstructed, a slow release relay, circuit means including said contact of the overload device to energize said slow release relay, and other circuit means including a back contact of said slow release relay to energize said control device to interrupt said motor operating circuit when said slow release relay is picked up and to reclose said motor operating circuit at the end of the slow release period of said slow release relay to periodically operate said motor as long as the signal is obstructed.

4. In combination, a highway crossing gate provided with a mechanism including a motor for raising the gate from an obstructing position to a clear position, a circuit controller operatively connected with said mechanism, a track relay responsive to traflic approaching the highway, a control relay, a slow release relay, a control circuit including a back contract of said slow release relay and a front contact of said track relay to energize said control relay, a motor operating circuit including a front contact of said control relay and a contact of said circuit controller opened only at said clear position to operate the motor, a time element relay having a normally open contact which becomes closed only after the relay has been energized for a predetermined time interval, an energizing circuit including a front contact of said control relay and a contact of said circuit controller closed during a preselected portion of the gate movement from the obstructing position to the clear position to energize said time element relay, and means including said contact of the time element relay to energize said slow release relay to govern said control relay and cause automatically the motor operating circuit to be periodically opened and then reclosed after a period equal to the release period of the slow release relay as long as the gate fails to raise said preselected portion of its movement in said predetermined time interval each time the motor is operated.

5. In combination, a highway crossing gate provided with, a mechanism including a motor for raising the gate from an obstructing position to a clear position, a circuit controller operatively connected with said mechanism, a track relay responsive to traflic approaching the highway, a control relay, a slow release relay, a time element relay having a normally closed back contact and a normally open front contact which front contact is closed only after the relay has been energized for a predetermined time interval; a control circuit including a front contactof said track relay, a back contact of said slow release relay and said back contact of said time element relay to energize said control relay; a motor operating circuit including a front contact of said control relay and a contact of said circuit controller opened only at said clear position to operate the motor, an energizing circuit including a front contact of said control relay and a contact of said circuit controller closed during a preselected portion of the gate movement from the obstructing position to the clear position to energize said time element relay, and another circuit including said front contact of said time element relay to energize said slow release relay.

6. In combination, a highway crossing gate provided with a mechanism including a motor for raising the gate from an obstructing position to a clear position, a circuit controller operatively connected with said mechanism, a track relay responsive to traffic approaching the highway, a control relay, a slow release relay, a control circuit including a front contact of the'track relay and a back contact of the slow release relay to energize said control relay, a motor operating circuit including a front contact of the control relay and a contact of said circuit controller to operate said motor to raise the gate, a time element relay having a normally open contact which becomes closed only after the relay has been energized for a predetermined time interval, another circuit including a front contact of the control relay and a contact of said circuit controller closed during a preselected portion of the gate movement from the obstructing to the clear position to energize said time element relay, and means including said contact of the time element relay to energize said slow release relay to govern said control relay and cause the motor operating circuit to be opened when the gate fails to raise said preselected portion of its movement in said predetermined time interval and the motor operating circuit to be reclosed at the end of the slow release period of said slow release relay to again attempt to raise the gate.

7. In combination, a highway crossing gate provided with a mechanism including a motor for raising the gate from an obstructing position to a clear position, a circuit controller operatively connected with said mechanism, a track relay responsive to traffic approaching the highway, a repeater relay controlled over a front contact of said track relay and a contact of said circuit controller closed only at the clear position of the gate, a slow release relay having a first energizing circuit including a front contact of the repeater relay, a control relay, a control circuit including a front contact of said track relay and a back contact of 'said slow release relay to energize said control relay, a motor operating circuit including a front contact of the control relay and a contact of said circuit controller to operate said motor to raise the gate, a time element relay having a normally open contact which becomes closed only after the relay has been energized for a predetermined time interval, another circuit including a front contact of the control relay and a contact of the circuit controller closed at a preselected portion of the movement of the gate from the obstructing position to energize said time element relay, and a second energizing circuit including said contact of the time element relay to energize said slow release relay whereby said motor operating circuit is periodically interrupted for periods equal to the release period of said slow release relay when the motor fails to raise the gate said preselected portion of its movement in said predetermined operating time of the time element relay.

8. In combination, a highway crossing gate provided with a mechanism including a motor for raising the gate from an obstructing position to a clear position, a circuit controller operatively connected with said mechanism, a track relay responsive to traific approaching the highway, a slow release repeater relay controlled over a front contact of said track relay, another slow release relay controlled over an energized circuit including a front contact of said repeater relay, a control relay, a control circuit including a back contact of said other relay and a front contact of said track relay to energize said control relay, a motor operating circuit including a front contact of said control relay and a contact of said controller opened only at said clear position to operate the motor to raise the gate, a time element relay having a normally open contact which becomes closed only after the relay has been energized for a predetermined time interval, another circuit including a front contact of said control relay and a contact of said controller closed at a preselected portion of the movement of the gate from the obstructing position to energize said time element relay, and said cont-act of the time element relay interposed in said energizing circuit of said other slow release relay to energize said other slow release relay whereby said motor operating circuit is periodically interrupted for periods equal to the release period of said slow release relay when the motor fails to raise the gate said preselected portion of its movement in said predetermined operating time of the time element relay.

9. In combination, a highway crossing gate provided with a mechanism including a motor for raising the gate from an obstructing position to a clear position, a circuit controller operatively connected with said mechanism, a track relay responsive to traffic approaching the highway, a slow release repeater relay, another slow release relay,

an overload relay having a first and a second winding, a circuit including a front contact of the track relay and a back contact of said overload relay to energize said repeater relay; a motor operating circuit including a front contact of said repeater relay, said first winding of the overload relay and a contact of said controller opened only at the clear position to operate the motor to raise the gate; said first winding effectively energized to pick up said overload relay and release said repeater relay to interrupt the motor operating circuit only when the gate is obstructed and an overload current flows in the motor operating circuit for a time interval determined by the degree of the overload, another circuit including a front contact of said overload relay and a front contact of said repeater relay to energize said other slow release relay, and a stick circuit including either a front contact of said repeater relay or a front contact of said other slow release relay and said second winding of the overload relay to retain said overload relay picked up for a period equal to the sum of the release periods of said repeater relay and said other relay subsequent to an overload condition.

10. In combination, an operated device provided with a mechanism including a motor for moving the device from a first to a second position, a control device operative at times to close a contact, a slow release repeater relay, another slow release relay, an overload relay having a first and a second winding, a control circuit including said contact of said control device and a back contact of said overload relay to energize said repeater relay, a motor operating circuit including a front contact of said repeater relay and said first winding of the overload relay to operate said motor to move said operated device, said first winding effectively energized to pick up said overload relay only when an overload condition exists on said operated device and an overload current flows in said motor operating circuit for a time interval whereby said repeater relay is released to interrupt the motor operating circuit under such overload condition, circuit means including a front contact of said overload relay and a front contact of said repeater relay to energize said other slow release relay, and a stick circuit including a front contact of said other slow release relay and said second winding of the overload relay to retain the overload relay energized until the end of the release period of said other relay to cause said motor to be periodically operated to attempt to move said operated device as long as the overload condition persists.

11. In combination, a first and a second highway crossing gate located at the intersection of a railway with a highway and each gate provided with a mechanism including a motor for raising the gate from an obstructing to a clear position and a. circuit controller, a track relay responsive to railway trafilc approaching the intersection, a repeater relay controlled over a front contact of said track relay and a contact of the controller of each of said gates closed at the clear position only, a slow release relay controlled over a front contact of said repeater relay, a first and a second control relay for said first and second gates respectively, and each said control relay controlled over a back contact of said slow release relay, a first motor operating circuit including a front contact of said first control relay for operating the motor of said first gate, a second motor oper ating circuit including a front contact of said second control relay for operating the motor of said second gate, a first and a second time element relay each having a normally open contact which becomes closed after the relay has been energized for a predetermined time interval, a first energizing circuit including a front contact of the first control relay and a contact of the controller of the first gate closed when the gate is at the obstructing position for energizing said first time element relay, a second energizing circuit including a front contact of the second control relay and a contact of the controller of the second gate closed when the gate is at the obstructing position for energizing said second time element relay, circuit means including either the contact of the first time element relay or the contact of the second time element relay for energizing said slow release relay when either gate is held at its obstructing position for said predetermined time interval for interrupting the motor operating cir cuit for the motor of such gate, a first stick circuit including a contact of the controller of said first gate when raised a preselected height above its obstructing position to energize said first control relay, and a second stick circuit including a contact of the controller of said second gate when raised apreselected height above its obstructing position to energize said second control relay.

12. In combination, a first and a second highway crossing gate located at the intersection of a railway with a highway and each gate provided with a mechanism including a motor for raising the gate from an obstructing to a clear position and a circuit controller, a track relay responsive to railway traffic approaching the intersection, a slow release repeater relay controlled over a front contact of said track relay, another slow release relay controlled over a, front contact of said repeater relay and a back contact of said track relay, a first and a second control relay, a first control circuit including a back contact of said other relay and a front contact of said track relay to energize said first control relay, a second control circuit including a back contact of said other relay and a front contact of said track relay to energize said second control relay, a first motor operating circuit including a front contact of said first control relay to operate the motor of the first gate, a second motor operating circuit including first time element relay, a second energizing circuit including'a front contact of the second control relay and a contact of the controller of the second gate closed at the obstructing position to energize said second time element relay, circuit means including either the contact of said first time element relay or the contact of said second time element relay to energize said other slow release relay when either gate isheld at its obstructing position for said predetermined time interval to interrupt the motor operating circuit for the motor of such gate, a first stick circuit including a contact of the controller of the first gate closed when the gate is raised a preselected height above the obstructing position to energize said first control relay, and a second stick circuit including a contact of the controller of the second gate closed when the gate is raised a preselected height above the obstructing position to energize said second control relay.

13. In combination, a first and a second signal mechanism each of which includes a motor for operating the mechanism from a first to a second position, a first and a second controller operatively connected with said first and second signal mechanisms respectively, a control element, a slow release relay, a first and a second control relay each of which is controlled at times over a contact of said control element and a back contact of said slow release relay, a first motor operating circuit including a front contact of said first control relay for operating the motor of said first signal mechanism, a second motor operating circuit including a front contact of said second control relay for operating the motor of said second signal mechanism, a first and a second time element relay each of which has a normally open contact that becomes closed only after the relay has been energized for a predetermined time interval, a first energizing circuit including a contact governed by said control element and a contact of said first controller closed at the first position of said first signal mechanism to energize said first time element relay, a second energizing circuit including a contact governed by said control element and a contact of said second controller closed at the first position of said second signal mechanism to energize said second time element relay, circuit means including either the contact of said first time element relay or the contact of said second time element relay to energize said slow release relay, a first stick circuit including a contact of said first controller when said first signal mechanism is moved a preselected distance away from its first position to energize said first control relay, and a second stick circuit including a contact of said second controller closed when said second signal mechanism is moved a preselected distance away from its first position to energize said second control relay.

14. In combination, a signal mechanism provided with a motor to move such mechanism from a first to a second position, a circuit controller operatively connected with said signal mechanism, a control relay, a motor operating circuit including a front contact of said control relay and a contact of said controller to operate the motor, a normally deenergized overload relay having a normally open contact which becomes closed only after the relay is efiectively energized for a predetermined time interval, means to associate said overload relay with said signal mechanism as required to effectively energize said overload relay when said motor is operated with the signal mechanism obstructed, and means including a slow release relay controlled over said contact of the overload relay and effective to deenergize said control relay to interrupt said motor operating circuit when said overload relay is effectively energized for said Predetermined time interval and to subsequently reenergize said control relay at the expiration of the slow release period of said slow release relay to cause a second operation of the motor to move the signal mechanism,

15. In combination, a" highway crossing gate provided with a mechanism including a motor for raising the gate from an obstructing position to a clear position, a control relay governed by railway traffic approaching the highway, a motor operating circuit including a front contact of said control relay to cause the motor to be operated to raise the gate, a normally deenergizedoverload device having a control element associated with said gate mechanism to cause effective energization of the overload device when the gate is held in the obstructing position with the motor operating for a predetermined time interval, and automatic means including a slow release relay governed by said overload device and operative to deenergize the control relay and interrupt the motor operating circuit when said overload device is eifectively energized and to subsequently reenergize the control relay at the end of the slow release period of said slow release relay for periodically operating the motor when the gate is held at the obstructing position.

16. In combination, a highway crossing gate provided with a mechanism including a motor for raising the gate from an obstructing position to a clear position, a. circuit controller operatively connected with said mechanism, a control relay governed by railway traific approaching the highway, a motor operating circuit including a front contact of said control relay and a contact of said circuit controller opened only at said clear position to operate the motor to raise the gate, an overload relay having a control element associated with said gate mechanism to efiectively energize the control element when the gate fails to raise for a predetermined time interval with the'motor oper-