US2114554A - Track shunting apparatus - Google Patents

Description

Patented Apr. 19, 1938 UNITED STATES PATENT OFFlCE TRACK SHUNTING APPARATUS Application January 9, 1933, Serial No. 650,799

9 Claims.

My invention relates to track shunting apparatus and more particularly to apparatus for shunting track circuits by light weight rail vehicles having steel wheels or pneumatic tired wheels.

I will describe two forms of track shunting apparatus embodying my inventionand will then point out the novel features thereof in claims.

The track shunting apparatus set forth in my present application is somewhat similar to that set forth in the two copending applications of Howard A. Thompson, Serial No. 617,137, filed on June 14, 1932, for Apparatus for shunting of track circuits, and Serial No. 629,030, filed on August 16, 1932, for Apparatus for decreasing rail contact resistance, and the said copending applications contain claims which cover broadly certain features of the invention described in my present application.

Fig. l of the accompanying drawing is a diagrammatic view showing the electrical connections of the track shunting apparatus. Fig. 2 is a diagrammatic view showing the apparatus for regulating the contact pressure of the rail shoes shown in Fig. 1. Fig. 3 is a modification of a portion of the circuit illustrated in Fig. 1.

Similar reference characters refer to similar parts'in each of the figures.

In shunting a track by means of a pair of rail 30, shoes which apply a voltage across the two rails for breaking down the rail film resistance, it has been found that, within certain limits, an increase in the pressure with which the rail shoes bear upon the rail surface results in a decrease 35 of the voltage and current required for establishing a satisfactory shunting path, this de crease being desirable from the standpoint of power economy because, usually, this voltage and current must come primarily from the car-car- 40 ried storage battery. On the other hand, if a high shoe pressure is used, this pressure will add a substantial friction load, particularly at high speeds, which must be overcome by the motive power of the car, and which is therefore not desirable.

Assuming for example, that under average conditions with a relatively clean rail surface, a given voltage and current on the car will give satisfactory shunting with a rail shoe pressure of 50 pounds per shoe, it may be found that under certain conditions of rail surface a shoe pressure of 50 pounds may be required. Such conditions may arise as a result of the rust film which forms on the rail surface following a shower, or

55 the film present on the rails of a seldom used form a thin layer upon the rail surface. '5

One object of the apparatus embodying my invention is to regulate the shoe pressure in such manner that under normal conditions, a light pressure will be used, whereas under adverse conditions of rail surface, additional pressure will 10 become automatically effective to aid shunting of the track, the increased pressure being removed by manual action taken by the car operator, or automatically upon the expiration of a predetermined time interval. 15

Referring to Fig. 1 of the drawing, the apparatus therein disclosed is intended to be carried on a rail car which travels on rails I and 2 of the track. The film break-down voltage is furnished by the alternating current generator G, 20 driven by a motor M energized from the car battery CB, and is applied across rails l and 2 by means of two secondary windings 3 and 4 of transformer T. It will be noted that the instantaneous polarities of windings 3 and 4 are such 25 that these windings are series-aiding in causing the film breakdown current to fiow in the circuit which includes rail shoes 6-1 and 8-41. If the breakdown current is of sufficient magnitude, as determined by track shunting considerations, windings ill and H of current transformer T which are connected in such manner as to aid each other, will induce a suflicient voltage in secondary winding 12 to pick up indication relay K, through the rectifier R, whereupon indicator L will become energized over front contact 13 of relay K to supply an indication that safe shunting is being provided by the apparatus.

The apparatus thus far referred to is illustrated and described in a copending application for United States Letters Patent, Serial No. 644,180, filed Nov. 25, 1932, in the name of Bernard E. OHagan, for Track shunting apparatus.

The reference character SR designates a slowreleasing stick relay which is controlled by the normally open push button PB and by relay K. Assuming relay SR to have been picked up, a stick circuit will become effective for maintaining this relay in its energized condition, which circuit may be traced from one terminal B of a source, front contact M of relay SR, wire l5, front contact i6 of relay K, wire 11, and winding of relay SR, to the other terminal C of the source.

As long as relay SR remains energized, air valve AV will also remain energized over front contact l8 of relay SR, for a purpose to be explained in detail hereinafter.

Should relay K become deenergized for any reason, such as a decrease in the film breakdown current below a value at which safe shunting can be obtained, the above stick circuit for relay SR will become interrupted at front contact [6, and relay SR will release, releasing the air valve. Relay SR can not again be picked up until relay K picks up and push button PB is depressed to close the pickup circuit for relay SR. Indicator N, energized over back contact E8 of relay SR, is provided for the purpose of informing the car operator that high pressure is being applied to the rail shoes, in order that he may know when manual action may be taken to release the increased pressure.

Referring now to Fig. 2, the reference character P designates a piston which is normally held down against the compression of a spring S, by air pressure in the cylinder 1). Piston P operates a pair of arms is and 2t), pivoted upon studs 2! and 22, respectively, in such manner that when the piston is depressed by the air pressure, weights W1 and W2 will be lifted from the collars 23 and 2d, and will exert no pressure upon the members 25 and 25 of the respective rail shoes 6 and I. This will be the condition maintaining when the valve AV is energized to admit fluid pressure from a suitable reservoir not shown in the drawing to the cylinder D. When the valve AV becomes deenergized, the main reservoir pressure will be cut off and the pressure within cylinder D will be released to atmosphere by any suitable valve arrangement well known in the art, as a result of which the piston P will rise, causing weights W and W to act upon the shoes 6 and l, thereby increasing the shoe pressure. If desired, spring pressure or pressure produced in any other suitable manner may be substituted for the weights W and W In order to avoid short circuiting of the rail shoes, the shoe rigging and other mechanical connecting elements should be separated by suit able insulating members, as indicated for example, at 27 and 28. It will be understood that a duplicate piston such as P, controlled by the valve AV, will be used to regulate the pressure of shoes 8 and 9, or, if desired, one piston may be used to regulate the pressure of all four shoes, by means of a suitable mechanical linkage.

Referring to Fig. 3, the reference character TE designates a time element relay, the purpose of which is to provide an alternate method whereby push button PB becomes closed automatically upon the expiration of a predetermined time interval following the application of high pressure to the rail shoes and the subsequent pickup of relay K. Relay TE is energized over a series circuit including back contact l8 of relay SR and front contact 32 of relay K, so that the time interval begins to be measured from the moment a satisfactory shunt is established, the increased shoe pressure being released when relay TE comple es its operating stroke and closes PB.

From the foregoing explanation, it will be clear that as long as the condition of the rail surface is such that satisfactory shunting may be obtained with low rail shoe pressure, relays K and SR will remain energized, to maintain a low value of shoe pressure. However, as soon as a rail surface of high resistance is encountered, relays K and SR and valve AV will become deenergized, thereby producing an increase of the shoe pressure, whereupon relay K will again pick up, but relay SR and valve AV will remain deenergized until action is taken by the car operator to close the manually operable contact PB which completes the pickup circuit for relay SR, or until a suificient time interval has elapsed to permit relay TE to operate, if the circuit of Fig. 3 is used. If a contact such as PB were not used, and the pickup circuit for relay SR were to be controlled directly by a front contact of relay K, undesired pumping action of the apparatus might result, since passage of the car over a high resistance rail surface would cause a release of the valve AV, whereupon the shoe pressure would increase to pick up relay K and the valve again decreasing the pressure to its former insuflicient value, with the result that the above cycle might be repeated many times before a stretch of track witha low resistance rail surface was reached.

If preferred, the closing of contact PB to remove the hi h shoe pressure can be accomplished in any one of numerous suitable ways, other than automatically or by direct manual action of'the car operator. For example, contact PB can be a contact of a car door control relay, becoming closed each time that the operator takes action to open the car doors when making a station stop. Contact PB can also be operated by the electrical controller of the car, becoming closed only when the controller is in the off position. This allows resetting of the equipment to the low shoe pressure condition by a momentary movement of the controller to the off position, following the loss of shunt as indicated by lamp L. It will be apparent that the use of relay TE as well as of the indicator N is optional. Furthermore, it is obvious that the apparatus embodying my invention is not confined to the particular shunting system illustrated, but may be applied to any system using film breakdown current for establishing a low resistance shunting path.

The reason for using a relay SR having a slowrelease characteristic is to prevent momentary releases of the indication relay K such as may occur when passing over a switch, etc., from causing a release of the valve AV, and an unnecessary increase in the shoe pressure. If a set of the shunting apparatus is installed at each end of the car, one relay SR for both sets may be used to control either one valve for all the shoes on the car, or two valves, one for each set of the apparatus. Should an increase in pressure on all the shoes of the car be desirable when the indication, at one end only of the car is lost, this may be accomplished by including a front contact of each of the front and rear indication relays in the pickup and stick circuits for the relay SR.

Although I have herein shown and described only two forms of track shunting apparatus embodying 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 with a rail vehicle and a section of railway track, a source of current on said vehicle; a track shunting circuit including a pair of rail shoes, one for each rail, for applying a potential from said source across the two rails of said track for causing a film breakdown current to flow through-the rail film between said shoes and the rail surface to break down the resistance of the film to aid shunting of said track; pressure regulating means controlled by a decrease of said film breakdown current below a predetermined value for increasing the pressure of said shoes upon the rail surface, and manually controlled. means for releasing said increase of pressure provided said breakdown current is at or above said predetermined value.

*2. In combination with a rail vehicle and a section of railway track, a source :of current on said vehicle, a circuit including a pair of rail shoes for applying a potential from said source across a portion of the rail surface for causing a film breakdown current to flow through the rail film between said shoes and the rail surface to break down the resistance :of the film to aid shunting of said track, pressure regulating means controlled by said film breakdown current and effective to automatically increase the pressure of said rail shoes when said current decreases below a predetermined value, and manually controlled means for releasing said increase of pressure provided said breakdown current is at or above said predetermined value.

3. In combination with a rail vehicle and a section of railway track, a source of current on said vehicle, a circuit including a pair of rail shoes for applying a potential from said source across a portion of the rail surface for causing a film breakdown current to flow through the rail film between said shoes and the rail surface to break down the resistance of the film to aid shunting of said track, a first relay controlled by said film breakdown current in such manner as. to remain energized when said current is at or above a predetermined value and to release when said current decreases below said predetermined value, a second relay, .a normally open manually controlled contact, a pickup circuit for said second relay including a front contact of said first relay and said normally open contact, a stick circuit for said second relay including said front contact, and means controlled by said second relay when the second relay is deenergized for increasing the pressure of said rail shoes to aid the flow of said breakdown current.

4. In combination with a rail vehicle and a section of railway track, a source of current on said vehicle, a circuit including a pair of rail shoes for applying a potential from said source across a portion of the rail surface for causing a film breakdown current tov flow through the rail film between said shoes and the rail surface to break down the resistance of the film to aid shunting of said track, a first relay controlled by said film breakdown current in such manner as to remain energized when said current is at or above a predetermined value and to release when said current decreases below said predetermined value, a slow release relay, a normally open manually controlled contact, a pickup circuit for said slow release relay including a front contact of said first relay and said normally open contact, a stick circuit for said slow release relay including said front contact, fluid pressure apparatus for controlling the pressure with which said shoes bear upon the rail surface, and a fluid pressure control valve governed by said slow release relay for controlling said fluid pressure apparatus.

5. In combination with a rail vehicle and a section of railway track, a source of current on said vehicle, a circuit including a pair of rail shoes for applying a potential from said source across a portion of the rail surface for causing a film breakdown current to flow through the rail film, between said shoes and the rail surface to break down the resistance of the film to aid shunting of said track, a first relay controlled by said film breakdown current in such manner as to remain energized when said current is at or above a predetermined value and to release when said current decreases below said predetermined value, a second relay, a normally open manually controlled contact, a pickup circuit for said second relay including a front contact of said first relay and said normally open contact, a stick circuit for said second relay including said front contact, means controlled by said second relay when the second relay is deenergized for increasing the pressure of said rail shoes to aid the flow of said breakdown current, and an indicator controlled over a back contact of said second relay,

Si. In combination with a rail vehicle and a section of railway track, a source of current on said vehicle, a circuit including a pair of rail shoes for applying a potential from said source across a portion of the rail surface for causing a film breakdown current to flow through the rail film between said shoes and the rail surface to break down the resistance of the film to aid shunting of said track, a first relay controlled by said film breakdown current in such manner as to remain energized when said current is at or above a predetermined value and to release when said current decreases below said predetermined value, a second relay, means controlled by said second relay when said second relay is deenergized for increasing the pressure of said rail shoes to aid the flow of said breakdown current, said increase of pressure being released when said second relay is energized, a normally ineffective pickup circuit for said second relay, a stick circuit for said second relay including a front contact of said second relay, and means for at times rendering said pickup circuit effective.

7. In combination with a rail vehicle and a section of railway track, a source of current on said vehicle, a circuit including a pair of rail shoes for applying a potential from said source across a portion of the rail surface for causing a film breakdown current to flow through the rail film between said shoes and the rail surface to break down the resistance of the film to aid shunting of said track, a first relay controlled by said film breakdown current in such manner as to remain energized when said current is at or above a predetermined value and to release when said current decreases below said predetermined value, a second relay, means controlled by said second relay when said second relay is deenergized for increasing the pressure of said rail shoes to aid the flow of said breakdown current, said increase of pressure being released when said second relay is energized, a normally open pickup circuit for said second relay, a stick circuit for said second relay including a front contact of said first relay, and a time measuring device controlled by said second relay and efiective for closing said pickup circuit upon the expiration of a predetermined time interval following deenergization of said second relay provided said first relay is energized.

8. In combination with a rail vehicle and a section of railway track, a source of current on said vehicle, a circuit including a pair of rail shoes for applying a potential from said source across a portion of the rail surface for causing a film breakdown current to fiow through the rail film between said shoes and the rail surface to break down the resistance of the film to aid shunting of said track, a first relay controlled by said film breakdown current in such manner as to remain energized when said current is at or above a predetermined value and to release when said current decreases below said predetermined value, a second relay, a time element relay, a normally open contact governed by said time element relay in such manner as to become closed after a predetermined time interval following energization of said time element relay, means controlled by said second relay when said second relay is deenergized for increasing the pressure of said rail shoes to aid the flow of said breakdown current, a pickup circuit for said second relay including a front contact of said first relay and said normally open contact, a stick circuit for said second relay including said front contact, and an energizing circuit for said time element relay including a front contact of said first relay and a back contact of said second relay.

9. In combination with a vehicle designed for running on the rails of a railway track, a track circuit, a vehicle-carried shunt including at least two shoes which constantly engage the two rails of said track respectively for shunting said track circuit by conduction, pressure regulating means on the vehicle responsive to a given reduction in the current through said shunt for increasing the pressure with which said shoes engage said rails, and manually controlled means for releasing said increased pressure.

GEORGE W. BAUGHMAN.

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