US2092837A - Apparatus for shunting of track circuits - Google Patents

Description

Sept. 14, 1937. c. w. FAILOR ET AL APPARATUS FOR SHUNTING OF TRACK CIRCUITS Y Filed March 24, 1953 INVENZ'ORS y Ho 7 012.

To other cozzfam 81209.

'C/zarles WFaelor 072d ward/1172011078 (mm-16 I THEIR ATTORNEY Patented Sept. 14, 1937 NlTED STAT S areannrps FOR SHUNTING F TRACK CIRCUITS GharlesW. Failor, Forest Hills, and Howard A.

Thompson, Edgewood, Pa., assignors to The Union Switch & Signal Company; Swissvale, Pa, a corporation of Pennsylvania.

Application March 24, 1933, Serial No. 662,504

20 Claims.

Our invention relates to apparatus. for shunting of track circuits, and more specifically to apparatus for providing track circuit shunting by rail vehicles having wheels equipped with rubber tires, as well as for improving track circuit shunting by light weight steel-wheeled vehicles.

We will describe three forms of apparatus for track circuit shunting embodying our invention,

1'0 and will then point out the novel features thereof in claims.

The present application is a continuation in part of our copending application, filed 'June'24,

, 1932, Serial No. 619,080, for Apparatus for shunting of track circuits, in so far as the subject matter common to the two cases is concerned.

The apparatus for shunting of track circuits set forth in our present application is somewhat similar to that set forth inv the copending application of Howard A. Thompson, Serial No. 629g030, filed on August 16, 1932, for Apparatus for decreasing rail contact resistance, and the said copending application contains claims which cover broadly certain features of the invention described in our present application. In the accompanying drawing, Fig. 1 is an elevation of a rail vehicle equipped with the apparatus embodying our invention, shown diagrammatically. Figs. 2 and 3 are diagrammatic 3 views showing modified forms of the apparatus embodying our invention. Fig. 4 is a diagrammatic view showing a detail of construction of the apparatus illustrated in Figs. 1, 2 and 3.

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

Referring to Fig. 1 of the drawing, the reference character A designates a rail vehicle hav-:

ing wheel groups l and 2 which are insulated from the rails by insulating tread material, thereby being incapable of shunting the track through the medium of the ordinary wheel and axle shunt. The structure designated in general by the reference character D comprises two magnetic rail contact shoes S and S mounted upon magnet legs L and L it being understood that there are two such rail contact structures as D, one for each rail, although but one structure is illustrated for simplicity. The pole shoes S of the two structures are bonded togethed by a con-:

nector 5 of large section, thereby providing a low resistance path from rail to rail for shunting the track. The legs L and L of structure D: form the core of atransformer of whichthe windings P and S are primary and secondary same time forming p art eta magnetic circuit which includes, the rail portion between shoes S and S forcreatingw pressure. of" these shoes upon the railsurface. The block 5, of mag.- netizable material, is, separated from the legs L and L by insulating spacers 3 and 4' whichprovide an air gap in the magnetic circuit of" the transformer for a purpose to be explained hereinafter.

The primary winding P is constantly energized from the secondary of. a transformer T having a relatively highleak'age reactance, the primary of which transformer is'energized from a suitable alternating currentsource, such as a generator G, aboard car A, 'I'l'ie',;r eactive trans' former T is used for energizing the primary winding of the corresponding rail shoe s tructure I D, associated with the other rail;

When winding P is' energized', the f 1ui:; established in the core of structure D will induce a voltage in winding S of sufficient magnitude to cause: current to flow through. the contact, surfaces separating pole shoes S and; S and the rail. The path taken by thiscurrent, may be traced from one terminal of winding S, pole shoes the rail portion between shoes S v and S shoe S wire 1, resistor R, ,and Wire 8", to theother. terminal of winding S; As long as current continues to flow over the path' traced above foreach ofj the two structures D, any rail surface resistance-- film in the path of this current will be broken down, and. a positive track shunt will be estab lished bythe pair of pole shoes S bonded together by .wire 6. An indicator L is connected across a portion of resistor R for, giving an indication that current is actually'flowing in the rail path, i. e., that the surface resistance has been broken down. A similar indicator for the other structure D will show thejcondition of the contact being made with the remaining-rail. Should high rail contact resistance be encountered by pole shoes S and S the'decreased cur rent supplied by winding S under this condition,

voltage of transformer T will rise, producing a corresponding rise in thevoltages across windings P and S in order to enable the voltage of winding S-to puncture through the scale layer} or any other resistance film present on the rail contact surface. v n

The magnetic circuit or structure D'has an additional purpose, apart from pang "a. trans; former core for windings P and S. 'As will be apparent from the drawing, since the rail portion between shoes S and S forms a part of the magnetic circuit for structure D, there will exist a certain amount of adhesion or pull between shoes S and S and the rail surface, the strength of which adhesion, will depend upon the total number of flux lines passing from a pole shoe into the rail.

The purpose served by spacers 3 and 4 is to introduce a fixed air gap into the magnetic circuit, which air gap is relatively large as compared with the air gap represented by a scale layer between a pole shoe and the rail. In this manner, provided that the output of winding S is uniform, which condition depends upon good electrical contact of the shoes with the 'rail, the total number of flux lines and therefore the pressure exerted by the shoes upon the rail will be substantially uniform under most conditions, as car A travels along the track. Assuming, however, that appreciable rail contact resistance is encountered, the resulting increased Voltage across winding-P, delivered by transformer T as noted hereinbefore, will cause an increase in the total number of flux linespassing between the pole shoes and the rail, thereby increasing the pole shoe pressure to overcome the contact resistance, simultaneously with an increase in voltage from winding S to disrupt the resistance film. It will now be apparent that structure D provides high voltage and high mechanical pressure at the time when both of these factors are needed to overcome high Contact resistance'both Voltage and pressure remaining low when good electrical contact is being made, thereby decreasing the mechanical drag load on the driving motor of car A.

' Indicator L serves not only to check that current is flowing from winding S through the rail Pat but in addition, serves to check the integrity of insulations 3 and 4 because, should insulation 3 break down, resistor R and. indicator L will both become short-circuited through insulation 3 and wire 9. Also, should insulation 4 break down, winding S would become short-circuited upon itself through wire 9 and insulation 4, thereby deenergizing indicator L.

Referring to Fig. ,2 o f'the drawing, the modi: fid form of rail contact structure shown therein performs both functions of increasing the voltage and shoe pressure when poor electrical contact is being made, similarly to structure D of Fig. 1, and in addition, performs the function of imparting an oscillating motion, forward and back; to shoes S and S at the frequency of theoutput of generator G, to assist the removal of any resistance film by increased frictional movement. The legs L and L of the magnet of Fig. 2 are clamped rigidly to an insulating block K and have projections or pole pieces l0 and H, with an air gap therebetween. A compression spring F of non-magnetizable material, and insulated from legs L and L furnishes an opposing force to the force of attraction existing between poles l0 and II when winding P -is energized. The combination of legs L and L and spring F, is so proportioned and designed as to be tuned to mechanical resonance at the frequency of the output of transformer T so that there will exist at all times, when Winding P is energized, a move ment to and fro of the shoes S and S irrespective of whether car A is moving, or isat a standstill. Since satisfactory shunting is usually more important and also more diflicult to obtain with a car at a standstill, the apparatus of Fig. 2

provides certain advantages over the apparatus of Fig. l.

When winding P of Fig. 2 is energized from the secondary of reactive transformer T the voltage induced in winding S will cause current to flow through resistor R and the rail path in the same manner as described above in connection with Fig. 1, and indicator L associated with each contact structure will inform the car operator that rail current is flowing and that contact shoes S bonded by connector 5 are making good contact with each rail, for shunting the track. Should high rail contact resistance develop, the voltage of winding S will rise, the shoe pressure will increase, and since the total number of fiux lines passing between poles in and i l is increased,

the amplitude of the mechanical movement of legs L and L will also increase, all three of the above factors becoming simultaneously effective to overcome the rail contact resistance.

Referring to Fig. 3, the apparatus shown therein, accomplishes the same result which is obtained with the apparatus of Fig. 1, except that instead of utilizing magnetic attraction between the rail shoes and. a rail to increase the shoe pressure, air or other fluid pressure is used to supply the necessary increase in shoe pressure when high resistance rail film is encountered. The shoe structure D is similar to the structure D of Fig. l, but the members L and L of structure D can be made of non-magnetizable conducting material, if desired. The film breakdown potential is applied to rail I2 by means of shoes S and S which are connected across the secondary wind-- ing of transformer T through wires 2!) and 25, and the current limiting-reactor X.

When the car reaches a section of track having high film resistance, the breakdown current in the circuit of shoes S and S will decrease, increasing the potential across the two shoes due to the effect of reactor X, thereby aiding to disrupt the rail film. This, increased potential will also be effective across winding l3 of the solenoid magnet SM. The plunger of magnet SM has a magnetizable upper portion l4 and a non-magnetizable lower portion 55, so that downward pressure will be exerted on diaphragm E6 of the diaphragm valve DV, when winding i3 is energized.

The increase in downward pressure on diaphragm I6 resulting from the above increase in potential will cause the exhaust valve H to close more completely, at the same time increasingv slightly the opening at the admission valve l8, to permit added pressure from the reservoir to build up within the valve. The increase in pressure within the valve will be transmitted to the diaphragm piston DP which, through stud l9, will cause the rail contact pressure of shoes S and S to increase, thereby aiding to restore the normal flow of the breakdown current from transformer T i When breakdown current of a predetermined value is flowing in the circuit of shoes S and S winding 22 of the axle transformer T will be energized sufficiently to pick up the indication relay IR, through the rectifier M, thereby energizing lamp L over front contact 25. As a means for checking that the required amount of fluid pressure is at all times available, and that the circuit of winding 13 is notopen, a pneumatic aoeassv:

and shoes S and S will also decrease. Since there is no appreciable time lag in the response of the diaphragm valve DV and: piston DP, a

change in shoe pressure will occur almost instantly following a change in the-potential across winding I3. Q i

From the foregoing description, it will be apparent that I have provideda system in which, as the film breakdown current tends. to; decrease due to: increased film resistance or other causes, the shoe pressure will tend to beproportionately increased, thereby aiding to maintain a substantially uniform value of breakdown current, for eifective shunting, irrespectiveof variations in the resistance of the rail surface film.

The apparatus of Fig. 3 is similar, in principle, to the apparatus of Fig. 1-, the chief difference being that in- Fig. 1, magnetic attraction is used to increase the rail shoe pressure, whereas in Fig. 3, fluid pressure is used for performing the same function. The apparatus of each of the Figures 1, 2 and 3, provides a method for increasing the shoe pressure in accordance with a de-- crease in the film breakdown current, that is, the shoe pressure becomes automatically adjust ed in accordance with theefiectiveness of the rail shunt being provided. If desired shoes S and S of Fig. 3 can be placed. across the two rails of the track, eliminating connection 6 and the sec-- ond shoe structure associated with the other rail;

wires 29, 2! and secondary winding of transformer T serving in conjunction withthe structure D as a shunt path from one to the other rail, as Well as the film breakdown current path.

It will be obvious that the apparatus embodying our invention can be used. withequal. facility on light weight railvehicles having steel'wheels which do notv make dependable contact with the rails. Also, in order that car A may not. foul an adjoining track section or siding, it may be de-- sirable to position a pair of the rail contact struts.- tures at each end of the car, for maximum pro.- tection to traflic.

Although we have herein shown and described only three forms of apparatus. embodying our 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 our invention.

Having thus described our invention, what we claim is:

1. In combination with a rail vehicle and a" stretch of railway track, a magnetizable struc.-- ture carried by said vehicle having, a pair of spaced contact shoes electrically insulated from, each other upon said structure and in contact with a rail of said track, said. structure in conjunction with its associated rail forming a substantially closed magnetic circuit,'a primary and a secondary winding in inductiverelation. onsaidstructure, a connection from one terminal of said secondary winding to one of said shoes and from the other terminal of the secondary winding to,

the other shoe, a source of varying current, and means for supplying current from said source to said primary winding whereby said, shoes will exert pressure; uponthe rail due: to the flux which passes therebetween and whereby a voltage; from said secondary winding will be applied across said shoes to; break down the rail surface resistance between said shoes and, the rail.

2..I-n combination. with a rail vehicle and a stretchof railway track, a magnetizable structure carried bysaid'vehicle having a pairgof spaced contact shoes electrically insulated from each. other upon: said structure and in contact with arail of said track, said structure in con- Junction with its associated rail forming'a substantia-lly closed magnetic circuit, .a primary and a secondary winding in inductive relation on said structure, a. connection from one terminal of said secondary winding to one of said shoes and. from the other terminal of the secondary winding to the other shoe, a source of varying current,

and a transformer having, a high leakage reactance one-winding of which is energized from said source and the other winding of which supplies currentto said primary winding whereby said shoes will exert pressure upon the rail due to the; flux which passes therebetween andwherebya voltage from said secondary winding will be applied across said shoes to breakdown the rail surface resistance, between said shoes and the rail.

3., In combination with a' rail vehicle and a stretch of railway track, a magnetizable structure carried by said vehicle having apair of. spaced contact shoes; electricallyinsulated from.

each other upon said structure. and in contact I withv a. rail of said track, said structure inconjuntion withits associated rail-forminga substantially closed, fmagnetic circuit, a primary and; a secondary windingininductive relation. on said" 'structure,.a connection from one terminal of said secondary winding toone of said shoes, an impedance connected between the other terminal of said secondary winding and the other shoe, an indicator connected across a portion of said. impedance, a source of varying current, and means for supplying-current from said source tosaid primary winding wherebysaid shoes. will exert pressure upon the rail due to the flux which.

passes therebetweenand whereby a. voltage from said secondary winding will be applied across said. shoes to break down the rail surface resistance between said shoes and the rail. 7 1

4-. In combination wit-h a rail vehicle and a.

stretch of railway track, a divided U-shaped structure carried by said vehicle having a:first,..

second, and third magnetizable section, a nonmagnetizahleinsulati-ng spacer between said first and second and between said second and, third sections, twomagnetizable contact shoes one on the free end of said first section, and the other on the freeendof. said third section, said shoes making contact withv one'railof said track, a'pri-f mary and a secondarywinding in inductive relation on-said structure, a connection. from one terminal 01'- said secondary winding to one of said shoes, an-indicator connected between-the other terminal of the secondary winding and the other shoe, a" connection irom said second sectionof the structure tothe junction. point of said other former having a high leakage reactance one winding of which is energized from said source and the other winding of which supplies; our

rent-to said primary winding whereby said shoes which passes therebetween wherebyajvoltterminal or" the secondary winding with said. in-' dicator, a source of varying. current, and a'tr ansage from said secondary winding will be applied across said shoes to break down the rail surface resistance between said shoes and the rail. I

5. In combination with a rail vehicle and a stretch of railway track, a U-shaped magnetizable structure on said vehicle the legs of which structure are separated by a non-magnetizable insulating spacer, a magnetizable rail'contact shoe for each leg of said structure both shoes being in contact with a railfof said track, a primary and-a secondary winding in inductive relation on said structure, a connection from one terminal of said second secondary winding to one of said shoes and from the other terminal of the secondary winding to the other shoe, a source of varying current, and a transformer having a high leakage reactance one winding of which is energized from said source and the other winding of which supplies current to said primary winding whereby said shoes will exert pressure upon the rail due to the flux which passes therebetween and whereby a voltage from said secondary winding will be applied across said shoes to break down the rail surface resistance between said shoes and the rail.

6. In combination with a rail vehicle and a stretch of railway track; two magnetizable structures carried by said vehicle, one for each rail of said track, each having a pair of spaced contact shoes electrically insulated from each other upon the respective structure and in contact with'the associated rail, each structure in conjunction with its respective rail forming a substantially closed magnetic circuit; a low resistance connection from one shoe'of one structure to one shoe of the other structure for shunting said track, a primary and a secondary'transformer winding on each structure, a connection from one terminal of each of said secondary windings to one of said shoes associated therewith and from the other terminal of each secondary winding to the other shoe associated therewith, a source of varying current, and a transformer for each of said structures having a high leakage reactance one winding of each transformer being energized from said source and the other winding of each transformersupplying current to said primary winding of the structure associated therewith whereby both pairs of said shoes will exert pressure upon their respective rails due to the flux passing between the shoes and a railand whereby a voltage from each of said secondary windings will be applied across the shoes associated.- therewith to break down the rail surface resistance between said shoes and the rail.

7. In combination with a rail vehicle and a stretch of railway track, an open magnetizable structure on said vehicle having two legs insulated from each other and having a pair of pole pieces thereon separated by an air gap between the pole pieces; a pair of contact shoes, one for each leg, in contact with arail of said track; a primary and a secondary winding in inductive relation on said structure, a connectionfrom one terminal of said secondary winding to, one of said shoes and from the other terminal of the secondary winding to the other shoe, a source of varyingcurrent, and means for supplying current from said source to said primary winding whereby a pulsating flux at the frequency of said varying current will be established between said pole pieces for causing a movement ofthe legs of said structure to improve the rail contact, said flux being effective in causing said shoes to exert pressure upon the rail as well as to induce a voltage in said secondary winding for breaking down the rail surface'resistance between said shoesand the rail. 7

8. In combination with a rail vehicle and a stretch of railway track, an open magnetizab-le structure on said vehicle having two legs insulated from each other and having a pair of pole pieces thereon separated by an air gap between the pole pieces; a pair of contact shoes, one for each leg, in contact with a rail of said track; a non-magnetizable spring between said legs of the structure and insulated therefrom, the legs of the structure and said spring being so proportioned that said legs will oscillate at a predetermined frequency; a primary and a secondary winding in inductive relation on said structure, a connection from one terminal of said secondary winding to one of said shoes and from the other terminal of the secondary winding to the other shoe, a source of'varying current of said predetermined frequency, a transformer having a high leakage reactance one winding of which is energized from said source and the other winding of which supplies current to said primary winding whereby a pulsating flux will be established between said pole pieces for causing a movement of the legs of said structure to improve the rail contact, said flux being effective in causing said shoes to exert pressure upon the rail as well as to induce a voltage in said secondary winding for breaking down the rail surface resistance between said shoes and the rail.

9. In combination with a section of railway track and a rail vehicle, a source of current on the vehicle, a track shunt including a pair of rail shoes one for each rail of said track, means for passing current from said source through the rail film between said shoes and therail surface to break down the resistance of the film to aid shunting of said track, and means governed by said current for increasing the pressure of said shoes as said current decreases.

10. In combination with a section of railway track and a rail vehicle, a source of current on the Vehicle, a track shunt including a pair of rail shoes one for each rail of said track, means for passing current from said source through the rail film between said shoes'and the rail surface to break down the .resistance of the film to aid shunting of the track, and pressure regulating means controlled by said current and effective to automatically adjust the pressure of said rail shoes inversely with changes in the magnitude of said current. I

11. In combination with a section of railway track and a rail vehicle, a source of current on the vehicle, a track shunt including a pair of rail shoes one for each rail of said track, means for passing current from said source through the rail film between said shoes and the rail surface to break down the resistance of the film to aid shunting of the track, and fluid pressure means controlled by said current and effective to automatically adjust the pressure of said rail shoes inversely with changes in the magnitude of said current.

12. In combination with ,a section of railway track and a rail vehicle, a source of current on the 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 filmbreakdown current to fiow through the rail film between said shoes and the rail surface to breakdown the resistance of said film, and

pressure regulating means controlled by said film breakdown current and effective to automatically adjust the pressure of said rail shoes inversely with changesin the magnitude of said 7 for independently pressing each of said contact I means against the associated rail with a greater unit pressure than that with which said supporting wheels bear against the rails, and means connected across said contact means for short-circuiting the rails. r

15. In a rail car including a truck having side frames and wheels carried thereby supporting said truck on a pair of rails, contact means carried by said car on each side thereof having limited contact engagement with the adjacent rail, means for increasing the unit contact pressure of said contact means on said rails to a point above the unit pressure of said wheels on'said rails, and means for connecting the contact means on opposite sides of said car to short-circuit said rails, said last-named means being independent of said pressure increasing means.

16. In combination with a section of railway track, a source or" current, a track shunt having a pair of rail shoes, means for passing current from said source between the rail shoes and the respective rails, and means for automatically adjusting the pressure of said shoes in accordance with the magnitude of said current whereby the shoe pressure will beincreased with a decrease in the current to aid shunting of the track by said track shunt. V

17. In combination with a section of railway track, a source of current, a track shunt having a pair of rail shoes, means for passing current 7 from said source 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, and means governed by said current for varying the pressure of said shoes as said'current varies.

18. In combination with a section of railway track, a track shunt, means for passing current through the rail contacting portions of said track shunt to break down the rail film between said shunt and the rail surface to aid shunting of said track, and means forl varying the pressure with whichsaid track shunt bears on the rail surface as said current varies. V v

19. In combination with a section of railway track, a track shunt, means for passing current through the rail contacting portions of said track shunt to break down the rail film between said shunt and the rail surface to aid shunting of said track, and means for changing the rail contact pressure of said track shunt inversely with changes in the magnitude of said current.

20. In combination with a section oi railway track and a rail vehicle thereon, a pair' of rail contacts carried by said vehicle and presenting a limited area for continuous contact with the adjacent rail, means for pressing each of said contacts against'the associated rail with a greater unit pressure than that which said vehicle exerts on the rails due to its weight, and means connected across said rail contacts for short-circuit- V ing the rails.

CHARLES W; FAILOR. HOWARD A. THOMPSON.

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