Brakes – Vehicle – Railway
Reexamination Certificate
1999-03-31
2001-08-14
Oberleitner, Robert J. (Department: 3613)
Brakes
Vehicle
Railway
C188S25000B, C188S219100
Reexamination Certificate
active
06273219
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to railroad car brakes and will have special application to brake beams for use with railroad cars.
SUMMARY OF THE INVENTION
Conventional railroad car braking systems typically consist of opposed brake beams carrying brake pads disposed adjacent the wheels of the railroad car truck. To slow or stop the car, the beams are shifted along a predetermined linear path from a standby position to a braking position in which the brake pads frictionally engage the wheels. The beams are guided between the standby and braking positions by extensions projecting laterally from the ends of the beams into slots or pockets in the truck sidewalls. Such end extensions, however, occasionally become misaligned and lodged within the sidewall pockets due to irregularities in the end extensions, misaligned sidewall pockets, or railroad track curves and irregularities which shift the truck sidewalls relative to one another. Also, conventional beam ends have a tendency to bend in the direction of wheel travel due to braking torque and can eventually become permanently deformed. Such brake beam deformities can impair proper travel of the end extensions within the pockets. Furthermore, when a rail car couples with another car, the impact can shift one beam of each pair away from the wheels toward the center of the car truck where it can jam. Multiple braking applications may then be required to dislodge the beam and shift it far enough toward the wheels to provide proper braking.
Imperfect travel of the end extensions within the sidewall pockets can also produce undesirable brake pad wear. Many pads are replaced because one portion of the pad, usually either the top or the bottom, has worn to an unacceptable thickness due to beam misalignment. The material remaining on the rest of the pad is wasted.
Also, conventional pads tend to crack or brake upon initial contact with the wheel. When the adjacent wheel is worn or the beam is misaligned, only a corner or edge of the pad engages the wheel. This concentrates force at the perimeter of the pad and can crack or brake the pad and reduce its useful life.
The present invention provides a brake beam which is suspended between the truck sidewalls by a pair of pivot arms that guide the beam along an arcuate path between a standby and a braking, position. Each arm is attached to a beam end and pivotally mounted to the adjacent truck sidewall at a location offset from the axle. When a standard actuating mechanism urges the beam toward the wheels, the pivot arms swing the beam in a pendulum-like manner along a curved path toward the wheels into a braking position. The brake pads at the ends of the beam frictionally engage the wheels to slow or stop wheel rotation. The beam is swung back into the standby position in a similar manner.
In another embodiment of the invention, the brake pads are formed into a curved wedge with a cross-sectional width that decreases from the lower end to the upper end. A ridge protrudes from the braking side of the pad toward the adjacent wheel and extends between the lower end and the upper end of the pad to provide an initial point of contact between the brake pad and the wheel.
Since the beam assembly of the present invention does not use beam end extensions, the brake beam should not jam in position, thereby ensuring effective braking with one stroke of the actuating mechanism. Also, the pivot arms of the beam assembly resist beam end deformation. The braking force vectors created when the brake pads contact the rotating wheels are substantially absorbed as tension or compression force along the axis of the pivot arms.
Additionally, the curved or arcuate path of the pivot arms force a brake pad wear pattern that ensures that each pad is substantially fully worn, and therefore not wasted, at the time pad replacement is necessary. The wedge-shaped embodiment of the brake pad also extends the useful life of the pad since the entire thickness of the thicker, lower end of the pad must wear down before the remaining portions of the pad wear. Moreover, the ridge protruding from the brake pad permits the pad to gradually increase contact with the wheel to avoid cracking or braking at the beginning of the service life of the pad.
Accordingly, an object of the present invention is to provide a brake beam which will not be prone to jam or bind in an inoperable position.
Another object is to provide a brake beam which, unlike conventional beams, is designed not to jam in response to coupling of railroad cars.
Still another object of the present invention is to provide a brake beam which resists deformation due to braking torque.
Another object is to provide a brake beam which increases the useful life of the brake pads.
Other objects of this invention will become apparent upon a reading of the following, description.
REFERENCES:
patent: 3009544 (1961-11-01), Maloney et al.
patent: 3679028 (1972-07-01), Mulcahy et al.
patent: 4193480 (1980-03-01), Malo
patent: 4401197 (1983-08-01), Bohla et al.
patent: 4596311 (1986-06-01), Brodeur et al.
patent: 4771868 (1988-09-01), Haydu
patent: 5000298 (1991-03-01), Jackson et al.
patent: 5456337 (1995-10-01), Jackson
patent: 55-97537 (1980-07-01), None
Car Builders' Cycolpedia, 16 Edition 1943; pp. 1012 & 1017 as indicated; p. 1015—not indicated on copy Simmons, Boardman Publishing Corporation, 30 Church Street, New York City.
Baker & Daniels
Oberleitner Robert J.
Sy Mariano
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