US2730198A - Track brake assembly - Google Patents

Description

Jan. 10, 1956 w. T. ROSSELL TRACK BRAKE ASSEMBLY 2 Sheets-Sheet 1 Filed June 14, 1951 INVENTOR fl/LK/flm 729 5554 ATTORNEY Jan. 10, 1956 Filed June 14, 1951 W. T. ROSSELL TRACK BRAKE ASSEMBLY 2 Sheets-Sheet 2 In E INVENTOR. fizz/4m T 4 53f 41.

ATTORNEY United States Patent Office 2,730,198 Patented Jan. 10, 1956 TRACK BRAKE ASSEMBLY William '1. Russell, New York, N. Y., assignor to Transit Research Corporation, New York, N. Y., a corporation of New York Application June 14, 1951, Serial No. 231,452 2 Claims. (Cl. 188-41) This invention relates to magnetic track brakes having particular utility on transit rail vehicles and has for its object to provide an improved brake of this type which will follow the contours of the rails closely and which will therefore provide greater braking without increasing the size of the conventional brake shoe.

It is conventional practice to attach two brake shoes together by cross straps bolted securely thereto thus making a rigid assembly. The assembly is hung from springs so that the bottoms of the shoes normally ride close to and immediately above the rails. When current is applied to the coils contained within the shoes the shoes are pulled into contact with the rails. A suitable bracket carried by the frame of the vehicle truck contacts the shoes thus pushing them along the rails. The amount of braking which results depends upon the magnetic force which pulls the shoes against the rails and upon the area of contact between the shoes and the rails.

The surface of transit rails contacted by the shoes varies considerably. Their surfaces are worn by the tires of the vehicles which may be of cylindrical or conical initial shape but which are in various stages of wear, some portions of a rail will naturally wear faster than others, and various rails are of different ages and hence at various stages of wear. As a general statement it may be said that the track brakes will wear and will tend to take the mean of the shapes of all rails with which they have had contact. The result is that friction surfaces of the track brakes seldom have full contact with a given rail and the resultant braking is reduced accordingly.

The object of this invention is to introduce flexibility into the rigid track brake assembly, the flexibility being such that the track brakes under the influence of a strong magnetic force may be able to find greatly increased surface contact with the rails.

More specifically it is the principal object of the invention to provide resilient connections between one track shoe and the straps or cross-bars that connect it to the other shoe, the connections being capable of allowing a slight rotation of the shoe with respect to the cross-bars and also being capable of slight vertical movement of one end of the shoe with respect to the other, thus permitting universal movement of each shoe with respect to the cross-bars and with respect to the other shoe.

Other objects of the invention are to provide an arrangement which is very close to conventional track shoe assemblies in appearance and which may be converted to the teachings of this invention at a minimum of expense and in the shops of the operating companies.

Other objects and advantages will become hereinafter more fully apparent as reference is had to the accompanying drawings in which my invention is illustrated, by way of example, and in which Figure 1 is a side elevation of my improved track brakes, showing their attachment to a rail truck,

Figure 2 is a top plan view of the track brake assembly only, of Figure 1,

Figure 3 is an end view of the track brake assembly resting on rails.

Figures 4, 5, and 6 are end elevations of one brake shoe showing its adaptation to rails of different shapes, and

Figure 7 is a diametric section through a resilient connector which connects each shoe to a cross beam.

More specifically, 1 indicates the two shoes of a track brake. These shoes contain coils of wire (not shown) and are connected to a source of electric power (not shown) so that excitation of the coils sets up a magnetic field in the shoes which draws them to the rails 2.

The shoes 1 are equipped with brackets 3 at each end thereof to which coil springs 4 are attached at their lower ends. The upper end of each spring 4 is connected to a bracket 12 mounted on a side frame 5 of the rail truck of which the track brakes form a part. The brackets 3 are so formed that they serve as the means through which the shoes 1 are propelled along the rails 1. They project outwardly of the track shoes at each end thereof for abutting contact with brackets 6 fixedly secured to the side frames 5.

The foregoing is descriptive of a conventional type track brake. My invention is directed to the manner in which the shoes 1 are connected together as will now be described.

Extending transversely across the truck are the crossbars or cross-beams 7, two being illustrated although one or more than two may be provided. The ends of the cross-bars are each fixedly or integrally attached to a resilient coupling as shown in detail in Figure 7. The couplings are each composed of a metal cylinder 8 having a shaft 9 extending centrally therethrough. Rubber 10 fills the space between the members 8 and 9, being surface bonded to both thereof.

Either member of the coupling is attached to a crossbar and the other to a brake shoe 1. As illustrated, the

cross-bar 7 is fixedly secured at each of its ends to a cylinder 8. Bars 11 project outwardly from the shoes 1 to receive the bars 9 and to hold same against relative rotation by virtue of the keys 12.

The operation is as follows: the shoes 1 are maintained in spaced relation by the cross-bars 7. As they are pushed along the rails 1 by two abutments 6 they encounter rail surfaces of varying contours and surfaces which change within short distances. The flexible connections 8, 9, 10 permit movement of the shoes in a rotational direction around the bars 9 and the rubber by its nature permits one end of a shoe to tilt upward with respect to its other end and it further permits of slight movement of the bars 9 radially of the cylinders 8. Each track shoe under the influence of strong magnetic force can thus adjust itself to a closest possible fit and to maximum contact with a rail.

Figures 4, 5, and 6 illustrate three rail shapes commonly encountered and the accommodation of the shoes thereto. Figure 4 illustrates a rail in good condition. The shoe finds ready contact thereto without distortion of the rubber 10 in the connector. However, whether the rails are in good condition or not, one rail may be higher than the other so that flexibility in the connection of the shoes may improve the contact of the shoes with the rails.

In Figure 5 the rail 2 is illustrated as being worn on the outside portion of its surface. The shoe 1 must therefore tilt to the left in order to find good contact rotating the shafts 9 against the torsional resistance of the rubbers 10 of its mountings. Figure 6 illustrates a rail having a surface which has worn on its inside portion. In this case the shoe 1 must tilt to the right to find good contact therewith. This tilting is accompanied by a slight rotation of the shafts 9 against the torsional resistance of the rubbers 10, the rotation of the shaft 9 being in opposite direction to that illustrated in Figure 5.

In addition to the tilting of the shoes above described, or in lieu thereof, one end of a shoe may tilt longitudinally with respect to the other end by slightly distorting the rubber elements 10 and, further, the shafts 9 may be displaced radically, by slight amounts with respect to the cylinders 8. The shoes, therefore, can accommodate themselves to a wide variety of changing conditions of the track surfaces thus materially increasing their braking effects.

Various changes may be made in the details of construction and arrangement of parts and I therefore desire to be extended protection as defined by the scope of the appended claims.

What I claim is:

1. A track brake assembly comprising spaced parallel track shoes, at least one cross-bar extending between said shoes, a resilient mounting connecting each end of each of said cross-bars to one of said shoes, said mountings each comprising a metallic cylindrical member at the ends of each bar, said cylindrical members each having a core member centrally therethrough, and rubber occupying the space between said members and surface bonded to each of said members and non-rotatably secured to each thereof, one of said members being fixedly secured to one of said shoes in a direction paralleling the length of the shoe, the other of said members being fixedly secured to said cross-bar thereby permitting slight rotative movement of said shoes with respect to said cross-bar, said rubber resisting such rotative movement by torsion.

2. A track brake assembly comprising parallel track brake shoes, parallel bars extending from one of said shoes to the other thereof, the ends of each of said bars being formed as a loop, and means connecting the ends of said bars to said shoes comprising spaced brackets integral with said shoes, a pin nonrotatably mounted in each of said brackets with the pins in the brackets of each shoe being substantially coaxial with each other and substantially parallel to the length of said shoes, and a sleeve of rubber-like material enveloping said pin, each of said loops enveloping one of said sleeves, said sleeves each being surface bonded to their said pins and to said loops whereby relative rotation of said shoes about the axis of said pins is resisted by torsional stresses in said sleeves.

References Cited in the file of this patent UNITED STATES PATENTS 2,178,643 Piron Nov. 7, 1939 2,527,383 Zuckerman Oct. 24, 1950 FOREIGN PATENTS 469,847 France Mar. 17, 1914

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