US2220484A - Railway signaling apparatus - Google Patents

Description

Nov.- 5, 1940. o. M. JENSEN 2,220,484

RAILWAY SIGNALING APPARATUS Filed March 25, 1939 9 A 117 6" 7 I E1 21- 'L J 2 50% E c 25 c .B

- I 44' 6 m L- 56 INVENTOR 0660 Jensen.

HIS ATTORNEY Patented Nov. 5, 1940 UNITED STATES PATENT OFFICE Otto M. Jensen, Milwaukee, Wis., assignor to The Union Switch & Signal Company, Swissvale,

Pa., a corporation of Pennsylvania Application March 25, 1939, Serial No. 264,181

4 Claims.

My invention relates to railway signaling apparatus, and particularly to apparatus for the control of highway crossing signals.

A feature of my invention is the provision of 5 novel and improved means for checking a track circuit used to govern a signal control circuit.

A further feature of my invention is the provision of novel and improved means for controlling a time element device associated with a track circuit used to govern a warning operation of a highway crossing signal in response to a train occupying the track circuit, the time element device being eifective to discontinue such warning operation of the signal a predetermined time interval subsequently to the train occupying the track circuit. Other objects and advantages of apparatus embodying'my invention will appear as the specification progresses.

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

The accompanying drawing is a diagrammatic View of a preferred form of apparatus embodying my invention.

Referring to the drawing, the reference characters la and lb designate the track rails of a stretch of railway over which trafiic normally moves in the direction indicated by an arrow, and which railway is intersected at grade by a highway H, a highway crossing signal S being located at the intersection. The signal S may be any of the several well-known types and as here shown is an audible signal in the form of an electric bell.

The track rails la and intersection lfrom which traffic normally approaches the highway are formed by the usual insulated rail joints into two track sections DE and EF, a train traversing these track sections in the order named when approaching the intersection and the exit end of section EF being preferably located adjacent the highway. I shall call the section DE a first or normal operating section and the section EF a second or emergency operating section. The section EF would, ordinarily at least, be relatively short and of just sufiicient length to provide a desired period of warning operation of the signal S prior to the arrival of a train at the intersection when the train operates at a relatively low speed, and such warning operation is initiated when this low speed train first enters the section EF. The section DE is preferably of sufficient length so that section DE and the shorter section E-F providea desired period of the warning operation lb on the side of the of the signal S prior to the arrival of the train I at the intersection when the train traverses the two sections at the maximum permissible speed for all trains, the warning operation in this latter case being initiated when the train enters section DE and being continued of course while the train occupies section EF.

Specifically, such a track layout would be used where track section DE includes track switches leading to spur tracks or where a station is located adjacent the section. Hence some trains at least would occupy section DE for a relatively long period of time in switching or standing at the station.

Each of the track sections D--E and E F is provided with a track circuit. section DE, the normal track circuit includes a track battery 3 connected across the track rails at the entrance end of the section through a current limiting resistor 4, and a direct current track relay 2 whose operating winding 5 is connected across the rails of the exit end of the section over lead wires 6 and I, an impedance or reactance unit 8 being interposed in the lead wire 6. The section DE is also provided with an auxiliary or checking track circuit which in- I cludes a source of alternating current such, for example, as a track transformer 9, an alternating current track relay Ill, and two resistors ll and I2. As here shown, the primary winding l3 of transformer 9 has its two terminals BX and CX supplied with alternating current from any convenient source such as a generator not shown. The secondary winding Id of transformer 9 and the operating winding l5 of relay l0 areserially connected across the rails at the exit end of section DE by virtue of a circuit one side of which circuit can be traced from the left-hand terminal of secondary winding l4 over wire l6, resistor H, and lead wire I to rail lb; and the other side of which circuit can be traced from the right-hand terminal of secondary winding l4 over wire l'l, operating winding l5 of relay l0, wire l8, resistor l2, and lead wire 6 to rail la.

Normally, that is, when section D--E is unoccupied, the direct current relay 2 is effectively energized and picked up by the direct current supplied from the track battery 3, the impedance unit 8 ofiering but little resistance to the flow of direct current but being so proportioned as to I li In the case of substantially block the flow of alternating cur rent from the transformer 9 to the operating winding 5 of relay 2. Under this unoccupied condition of section DE, the alternating current flowing in the operating winding l5 of relay ll] is only the leakage current passing between the track rails due to the ballast resistance, the connection at battery 3 and the path through winding 5 of relay 2 and unit 8. This leakage current may or may not be suificient to energize relay I8 sufficiently to pick up the relay. As will shortly appear, it is immaterial whether or not the relay I8 is picked up when the section DE is unoccupied. In the drawing the relay I8 is illustrated as being released under the unoccupied condition of section DE. The resistors II and I2 are proportioned so that little direct current from battery 3 flows through the auxiliary circuit including the secondary winding I4 of transformer 9 and the operating winding I5 of relay I0 and hence this auxiliary circuit does not form a shunt path to relay 2 that materially affects the operation of relay 2.

When the track section DE is occupied by a train the track relay 2 is shunted and released in the usual manner. The additional alternating current caused to fiow due to the low train shunt resistance between the track rails efiectively energizes the alternating current relay I8 and that relay is picked up. The manner by which this operation of the alternating current track relay I8 is used to check the operation of the normal direct current track circuit will appear hereinafter.

The track section EF is provided with a direct current track circuit including a track battery I9 and a direct current track relay 28, the relay 28 being connected across the rails at the exit end of section E--F as will readily appear by an inspection of the drawing. The track battery I9 is connected across the rails of the section EF over two alternative paths. To be explicit, one terminal of battery I9 is connected with the rail lb over a lead wire 2|, and the other terminal of battery I9 is connected with the rail Ia over two alternative paths, one path including a current limiting resistance 22, front contacts 23 and 24 of relay 2 in multiple and lead wire 25. The other path includes resistor 22, wire 41, front contacts 26 and 21 in multiple of a relay 28 to be referred to later, and lead wire 25.

It follows that when section E-F is unoccupied the relay 28 is energized and picked up when either the track relay 2 of section DE is picked up closing front contacts 23 and 24, or when the relay 28 is picked up closing front contacts 26 and 21. When the track section EF is occupied by a train the relay 2!) is shunted in the usual manner irrespective of the condition of the relays 2 and 28.

The signal S is provided with a simple operating circuit easily traced and which includes a back contact 29 of a normally energized control relay 30 so that signal S is normally silent and is sounded to provide a warning operation when the relay 38 is deenergized. The relay 30 is normally energized over either one of two alternative circuits, one circuit extending from terminal B of a convenient source of direct current such as a battery not shown, front contact 3| of track relay 2, wire 32, front contact 33 of track relay 28, winding of relay 3!] and to terminal C. The other circuit extends from terminal B of the current source over back contact 34 and contact finger 36 of a thermal relay TH to be shortly described, wires 35 and 32, front contact 33 of track relay 28, winding of relay 30 and to terminal C.

The apparatus also includes a time element device here shown as a thermal relay TH and a stick relay 28. The type of thermal relay TH is immaterial and it may be any one of several of the well-known types. It is deemed sufficient for this application to say that relay TH is provided with a heater element 38 and two circuit controlling contact fingers 36 and. 31, the contact fingers being insulated from each other but mechanically connected as indicated by a dotted line so that the two move substantially in unison. When the heater element 38 is cold the two contact fingers 36 and 31 occupy the position illustrated in the drawing with contact finger 38 in engagement with the back or checking contact 34 and the contact finger 31 disengaged from the front contact 39. When the heater element 38 is supplied with heating current for a predetermined time interval, say for example 20 seconds, the contact fingers 36 and 31 are moved so that contact finger 38 is disengaged from back contact 34 and the contact finger 31 engages the front contact 39. When heating current is removed from the heating element 38 the heating element quickly cools and the contact fingers 36 and 31 are moved back to their normal positions, that is the positions illustrated in the drawing.

The relay TH is provided with a control or heating circuit which extends from terminal B over front contact 40 of relay I0, back contact M of relay 2, wire 44, back contact 42 of relay 28,

back contact 43 of relay 20, heater element 38 f and to terminal C. It is to be observed that this control or heating circuit is closed only when the alternating current relay I8 is picked up closing front contact 40, and the direct current track relays 2 and 20 are released closing back contacts 4| and 43, respectively.

The stick relay 28 is provided with a pick-up circuit that extends from terminal B over front contact 40 of relay I 8, back contact 4| of relay 2, wires 44 and 45, front contact 39 and contact finger 31 of thermal relay TH, winding of relay 28 and to terminal C. With relay 28 once picked up it is retained energized over a stick circuit that is the same as its pick-up circuit up to wire 44 and thence over front contact 46 and winding current track relay 2 is shunted and is released 3'5 but the alternating current relay I8 is energized at its pickup value by virtue of the train shunt, and this latter relay is thus picked up. With track relay 2 releasing to open front contacts 23 and 24 the first traced alternative path for conm necting track battery I9 with the rails of section E'-F is opened and hence track relay 28 is in turn also deenergized and released opening front contact 33 and closing back contact 43 due to the second alternative path being also open.

Since front contact 33 of track relay 28 is interposed in both circuits for the control relay 30, the relay 30 is deenergized and released to close back contact 29 with the result that the warning operation of the signal S is initiated. With both 1 track relays 2 and 28 released closing back contacts 4| and 43, respectively, and the alternating current relay I0 picked up closing front contact 40, the heating circuit for the thermal relay 'I'H is completed with the result that the relay TH is heated and operates its contact fingers 36 and 31 after the predetermined operating time of relay TH. The operation of contact fingers 36 and 31 opens back contact 34 and closes front contact 39 of relay TH. As soon as the front contact 39 is closed the pick-up circuit for relay 28 is completed and'that relay is picked up and then retained energized over its stick circuit. With the picking up of relay 28 closing front contacts 25 and 21 the alternative path for connecting the track battery l9 across the rails of section E--F is completed with the result that the track relay 2!) is again energized and picked up since the train is still in the section DE and the section EF is unoccupied. When relay 28 picks up opening back contact 42 the heating circuit for relay TH is opened and the heater element 38 of that relay is cooled so that its contact fingers 36 and 31 shortly move back to their normal positions. The closing of back contact 34 of the thermal relay TH completes the second one of the control circuits for relay 30 since track relay 20 is now picked up closing front contact 33 and relay 30 on picking up opens the operating circuit for signal S and the warning operation of the signal ceases. The signal S now remains silent as long as the train remains in the section DE.

When the train in section DE has completed its work and again moves forward toward the right, it will enter section EF at a relatively low speed. When the train enters the section EF and shunts track relay 20, the release of that relay opens front contact 33 and brings about the warning operation of the signal in the manner previously explained. The warning operation of the signal S prior to the arrival of the train at the intersection will be of sufiicient interval to assure safety for the highway users because the train speed is relatively low. When the train passes over the intersection to the right and vacates section EF, the trackrelay 20 is reenergized and picked up because the track relay 2 of the section DE is picked up when the train vacates section DE. With both track relays 2 and 20 picked up, the control relay 30 is reenergized and the warning operation of the signal ceases.

In the event a train moving at the usual speed approaches the highway from the left and passes through the track sections DE and EF without stopping, the warning operation of the signal S is initiated as soon as the train enters the section DE and shunts track relay 2 and the warning operation of the signal is then continued without interruption until the train passes over the intersection and vacates the section E--F because this train will pass through the section DE before the thermal relay TH has had time tocomplete its operation.

In the event the normal or direct current track circuit of section DE should fail due to a weakened track battery, or broken rail bond, or broken rail, or other loss of power, the release of track relay 2 to open front contacts 23 and 24 will disconnect the track battery I9 from the section EF and track relay 2!! will be deenergized and released with the result that the warning operation of the signal S is initiated. Such failure of the track circuit for section DE will tend to decrease the flow of alternating current so that the alternating current relay I!) will be deenergized. With relay [0 not picked up to close its front contact 40, the control or heating circuit for the thermal relay TH remains open after the track relay 2 is released and hence the time element device does not function to bring about an interruption of the warning operation of the signal S after a predetermined time. Heretofore when such time element devices have been provided with track circuits that govern the operation of a highway crossing signal a failure of the track circuit which causes a release of the track relay will initiate the operation of the signal and also cause operation of the time element device so that the warning operation of the signal is interrupted at the end of the predetermined time interval for the operation of the time element device. In such case, when a train next approaches the highway the warning operation of the signal is not initiated for that train until the train enters the emergency track section and the warming operation prior to arrival of the train at the intersection may be of so short a duration that it is oflittle use in protecting the highway users. It is to be seen, therefore, that with apparatus embodying my invention the superimposing of alternating current on the normal direct current track circuit provides a control for the time element device such that the time element device is rendered ineffective to discontinue the operation of the highway crossing signal when the track relay is deenergi'zed due to a failure of the track circuit. In other words, with apparatus embodying my invention, the thermal relay or time element device is effective to interrupt the operation of a highway crossing signal only when the track circuit is occupied by a train.

It will be understood, of course, that my invention is not limited to this one application but that this one use of apparatus embodying my invention will serve to illustrate the many places where the apparatus may be used.

Although I have herein shown and described only one form of railway signaling apparatus em- 4!) bodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a stretch of railway track intersected by a highway, a highway crossing signal located at said intersection, a track section formed on one side of said intersection, a track circuit for said section including a source of direct current and a direct current track relay connected across the rails at opposite ends of the section to normally energize said relay and to shunt said relay when a train occupies the section,

a source of alternating current, an alternating current relay, means to serially connect said source of alternating current and said alternating current relay across the rails of the section at the,

same end said direct current track relay is connected across the rails to energize said alternating current relay when a train occupies thesection, an operating circuit controlled by said direct current track relay when shunted to cause operation of said signal, a time element device, means governed by said device when operated a predetermined time interval to remove said operating circuit from the control of said direct current relay, and a control circuit for said device serially including a front contact of said alternating track relay and a back contact of said direct current track relay.

2. In combination, a stretch of railway track intersected by a highway, a highway crossing signal located at the intersection, a first and a sec-. ond track section formed on one side of the intersection and traversed in the order named by a train approaching said highway, a track circuit for each of said sections, said track circuits each including a source of direct current connected across the rails at one end of the associated section and a direct current relay connected across the rails at the other end of the associated section, a front contact of the track relay of said first section interposed in the connection of the current source of the second section, a control circuit including a front contact of the relay for said second section for governing the operation of said signal, a time element device operative when energized a predetermined period to establish a shunt path for the connection of the current source of the second section around said front contact of the track relay of the first section, a source of alternating current, an alternating current relay, means to serially connect said source of alternating current and said alternating current relay across the rails of said first section to energize that relay when a train occupies said first section, and an energizing circuit for said device serially including a front contact of said alternating current relay and a back contact of the direct current relay of said first section.

3. In combination, a stretch of railway track intersected by a highway, a highway crossing signal located at the intersection, a first and a second track section formed on one side of the intersection and, traversed in the order named by a train approaching said highway, a track circuit for each of said sections, each of said track circuits including a source of current connected across the rails at one end of the section and a track relay connected across the rails at the other end of the section, a front contact of the track relay for said first section interposed in the connection of the current source for the second section, a control circuit including a front contact of the track relay for said second section for governing the operation of said signal, a time element device operative When energized a predetermined time interval to establish a shunt path for the connection of the current source for the second section around said front contact of the track relay for the first section, another track circuit including the rails of the first section and a track relay connected to the rails to be picked up when the rails are shunted, and an energizing circuit including a front contact of the track relay of said other track circuit to energize said device.

4. In combination, a stretch of railway track intersected by a highway, a highway crossing signal located at the intersection, a first and a second track section formed on one side of the intersection and traversed in the order named by a train approaching said highway, a track circuit for each of said sections, each of said track circuits including a source of current connected across the rails at one end of the section and a track relay connected across the rails at the other end of the section, means including a front contact of-the track relay for the first section to interrupt the track circuit of the second section when the track relay for the first section is released, a control circuit including a front contact of the track relay for the second section for governing the operation of .said signal, a time element device having a normally open contact which becomes closed when the device is energized a predetermined time interval, means including said contact of the time element device when closed to close the track circuit of said second section when the trackrelay for the first section is released, an auxiliarytrack relay and a current source connected in series across the rails of said first section to pick up-such auxiliary relay when the rails of that section are shunted, and a circuit including a front contact of said auxiliary relay and a back-contact of the track relay for the second section to energize said time element device.

' OTTO M. JENSEN.

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