US2068754A - Car retarder for railroads - Google Patents

Description

Jan. 26,1937.

s. J. MACKEY CAR RETARDER FOR RAILROADS Filed May 13, 1931 BY JIM EI-INTOR I w Patented Jan. 26, 1937 PATENT OFFICE C'AR RETARDER FOR RAILROADS Stuart J. Mackey, Rochester, N. Y., assignor to General Railway Signal Company, Rochester,

Application May 13, 1931, Serial No. 536,959

5 Claims.

This invention relates in general to car retarders of the track brake type, and has more particular reference to improved means for varying the degree of retardation exerted by the retarder on the sides of passing car wheels.

In hump yard operation, and in other connections, it is desirable in using track brakes to be able to readily vary the degree of retardation exerted, in order to care for various speeds, various weights: of cars which it is desired to brake, etc. With the above and other considerations in mind, it is proposed, in accordance with the present invention, to provide a car retarder which operates on the weight principle, wherein the weight of the car itself produces the braking pressures, together with means for varying the lever arms for applying the braking pressures, whereby to vary at will the degree of retardation exerted.

In the present invention, either a portion of the entire weight carried by a car wheel, or the entire weight carried by a car wheel, can be used in producing retardation on such wheel, and the effectiveness of this'weight used is variable at will, dependent upon an adjustable lever ratio through which the force causing retardation, is applied.

Further objects, purposes and characteristic features will appear as the description progresses, reference being made tothe accompanying drawing showing, solely by Way of example, and in no manner whatsoever, in a limiting sense, one form which the invention can assume. In the drawing:-

Fig. l is a transverse sectional view, with parts shown in elevation, of an embodiment of the present invention.

Fig. 2 is a sectional view on line 2-2 of Fig. 1.

Fig. 3 is a sectional view on line 3-3 of Fig. 1.

Referring now to the drawing, there is shown ties I, on which are carried track rails 2, constituting a stretch of singletrack. At each side of each track rail 2, is a roller or support member 3, which rests on a, fixed horizontal supporting member 3 and yoking each pair of rollers 3, associated with each track rail, is a rigid yoke 4, of a general U-shape, pivoted at each of its ends,

to the respective roller 3, as by pivots 4 At each side of each track rail, is a brake shoe 5, carried by a brake beam 6, the outer bifurcated end 6 of which carries a bearing pin 1, which is snugly'slidable in a slot S formed in the respective end of the yoke 4, the slot S having an upper circular arcuate portion 8, and a lower portion 9, for purposes to be explained below.

An operating bell crank lever [0, having a slot H in its bifurcated upper arm for receiving the bearing pin 1, is mounted, as by a pivot pin l2, to any fixed member such as the abutment N3 The rollers 3 are grooved out as at 3 to receive 5 pin 1, and the inner bifurcation of the upper arm of lever ill. The lower end of the vertical arm of the bell crank lever H], is connected, as at 13, to one of rods l4 and l5, as the case may be, and these rods l4 and 15 are connected in turn, to an operating lever l6, pivoted at a fixed point II, and operable in either direction as indicated by the arrows l8, by any desired means, such as an electric motor, (not shown) or the like.

The adjusting lever system, just described, is somewhat similar to that shown in application 504,674 filed December 26, 1930. The rods l4 and l5, are connected to the bell crank levers Ill, in such manner that a movement of lever IS in one direction, results in either raising or lowering the 20 upper ends of all of the bell crank levers H], to' thereby slide the pins 1 and the brake beams 6, either upwardly or downwardly.

The brake beams 6 are normally supported by support plates 6 which are biased upwardly by springs or the like 6 The brake shoes 5, as shown in Fig. l, are formed, and positioned, to each have ,a lower inwardly projecting portion 5 for receiving either the tread or the flange of a passing car wheel, depending on whether it be at the outer or the inner side of the track rail; and an inwardly projecting braking face 5 which, when in active position, is forced against the side of a passing wheel to thus exert a retarding force thereon.

By moving the bell crank levers Ill, to lower the upper horizontal arms thereof, the pins 1 can be slid downwardly into the portion 9, of the slot S to thereby draw the brake shoes 5 away from the track rails 2, and out of position for contacting with a passing car wheel. In such position, the retarder is inoperative to exert any retardation, and a passing car is subjected to no braking.

By operating the bell crank levers ID in the opposite direction so as to raise the horizontal arms thereof, and thus move the bearing pins 1 upwardly in the slot S and into the arcuate portion 8 of such slot, the brake shoes 5 are positioned to receive more or less of the weight carried by the passing car wheels on their inwardly projecting portions 5 The arcuate portion 8, of the slot S, is an arc of a circle concentric with the center of pressure of the portion l": of the brake shoe 5 against the car wheel l9, whereby movement of pin 1 in the portion 8 of slot S does not tend to move the brake shoe 5 either toward, or away from, the car wheel, and hence such movement is entirely possible even while heavy pressures are being exerted between the brake shoes and the car wheels.

Thus, as the bell crank levers are moved by the adjusting lever system including the rods I4 and I5 etc., in an upward direction, the brake shoes 5 are first brought into a position to receive the passing car wheel and support more and more of the weight carried by each wheel until the wheel is lifted clear from the track rail, at the time the pin 1 enters the arcuate portion 8 of slot S. When the car wheel is once lifted from the rail by the brake shoes, further movement of pin 1 cannot result in any further weight being supported transferred from the rail to the brake shoe, but does result in raising the outer ends of the brake beams 6, to thereby vary the ratio,

(see Fig. 1) and increase the value of this ratio, as the outer end of the brake beam 6 is raised.

The distance a, is the horizontal distance from the pin 7 to the near side of the car wheel, while the distance 1) is the vertical distance from the pin I to the horizontal line passing through the center of pressure of the brake shoe on the side of the wheel. By taking moments about the center of pressure of a brake shoe against a car wheel side, we obtain the equation wa=fb, wherein a and b are as defined above, 10 is that part of the weight on a wheel, which is carried by the brake shoe in question, and 7 is the force pressing the brake shoe against the side of the car wheel. From the above equation, we find that,

and since the force f, is proportional to the retarding force, it is seen that the retarding force can be varied through wide limits by varying the ratio of a to b, the retardation approaching infinity as the brake beam 5 approaches a horizontal position.

With the above arrangement of parts, it is clear that as the weight carried by a car wheel is gradually transferred from a rail to a brake shoe, the retardation exerted on the car Wheel gradually increases up to the point where the entire weight is carried by the brake shoes due not only to the fact that the ratio and hence vary f and accordingly the retarding force, at will.

In order to accomplish the above variation in retardation, after the weight on a wheel is once fully supported by a brake shoe, it is necessary to move the outer end of a brake beam along an arc which is concentric with the center of pressure between the brake shoe and the car wheel, and since it is impractical to position a pivot point at this point of the center of pressure, the slot S is employed, as described above.

The above specific description of several forms of inventions, has been given solely by way of illustration, and is not intended, in any manner whatsoever, in a limiting sense. Obviously this invention can assume many difierent physical forms, and is susceptible of numerous modifications, and all such forms and modifications, are intended to be covered by this application, as come within the scope of the appended claims.

Having described my invention, I now claim:-

1. In a car retarder of the track brake type, in combination with a track rail, a brake shoe at each side of the track rail, a downwardly inclined shoe beani at each side of the track rail and carrying its respective brake shoe, means for moving the shoe beams to cause the brake shoes to support a passing car wheel entirely free of the track rail, and means for thereafter moving the outer ends of the brake beams upwardly along an arc concentric with the point of pressure between the brake shoe and the car wheel.

2. In a car retarder of the track brake type, in combination with a track rail, a brake shoe at each side of the track rail, a downwardly inclined shoe beam at each side of the track rail which shoe beam carries its respective brake shoe, means for moving the shoe beams to cause the brake shoes to support a passing car wheel entirely free of the track rail, said means including a pin carried by the outer end of the brake beam and a slotted member within the slot of which the pin is slidable, which slot is concentric with the center of pressure between the brake shoe and the car wheel.

3. In a car retarder of the track brake type, in combination with a track rail, a brake shoe at each side of the track rail, 9. downwardly inclined shoe beam at each side of the track rail and carrying its respective brake shoe, means for moving the shoe beams to cause the brake shoes to support a passing car wheel entirely free of the track rail, said means including a pin carried by the outer end of the brake beam and a slotted member having a slot within which the pin is slidable, and which slot is concentric with the center of pressure between the brake shoe and the car wheel, and a lever system for moving the pin in said slot.

4. In a car retarder of the track brake type, in combination with a track rail, a brake shoe at each side of the track rail, a downwardly inclined shoe beam at each side of the track rail and carrying its respective brake shoe, means for moving the shoe beams to cause the brake shoes to support a passing car wheel entirely free of the track rail, said means including a pin carried by the outer end of the brake beam and a slot within which the pin is slidable, which slot is concentric with the center of pressure between the brake shoe and the car wheel, and a lever system for moving the pin in said slot and including a bell crank lever having a bifurcated end embracing said pin. I

5. In a car retarder of the track brake type, in combination with a track rail, a brake shoe at each side of the track rail, a downwardly inclined shoe beam at each side of the track rail and carrying its respective brake shoe, means for moving the shoe beams to cause the brake shoes to support a passing car Wheel entirely free of the track rail, said means including a pin carried by the outer end of the brake beam and a slot within which the pin is slidable, which slot is concentric with the center of pressure between the brake shoe and the car wheel, and a lever system for moving the pin in said slot, said slot including a non-concentric portion directed away from the track rail for thereby moving the brake shoes away from the track rail.

STUART J. MACKEY.

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