Brakes – Operators – Fluid pressure
Reexamination Certificate
1999-07-21
2001-08-07
Oberleitner, Robert J. (Department: 3613)
Brakes
Operators
Fluid pressure
C188S15100A, C188S348000, C188S072400
Reexamination Certificate
active
06269916
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates, in general, to a brake cylinder for use in railway vehicle brake assemblies and, more particularly, to a brake cylinder using a dual piston assembly with two sealing surfaces for generating forces under varying load conditions for initiating a braking sequence in railway vehicle brake assemblies. The brake cylinder of the invention is especially suitable for truck-mounted braking assemblies.
BACKGROUND OF THE INVENTION
As is generally well known in the railway industry, truck mounted braking systems comprise a series of force transmitting members, levers and linkages which function to move a group of brake shoes against the wheels of a railway vehicle to effect stoppage of such railway vehicle. A pneumatically activated brake cylinder is typically provided in the braking system to initiate movement of this series of force transmitting members, levers and linkages to apply the brakes of the railway vehicle. A well known type of truck mounted braking system is a TMX® truck mounted braking system (TMX® is a registered trademark of Westinghouse Airbrake company, the assignee of the present invention).
A currently used pneumatically activated brake cylinder for TMX® truck mounted braking systems is shown in FIG.
2
and comprises an air cylinder piston which moves in a forwardly direction within a cylindrical member upon the application of pneumatic pressure thereto. A sealing means is provided on, or adjacent, a first end of the piston. This sealing means contacts the inner surface of the cylindrical member so as to provide an airtight chamber at one end of the cylindrical member such that application of pneumatic pressure therein and against the first end of the piston enables forward movement of the piston. A piston rod is attached at a second end of the piston and moves in accordance with movement of the piston. An opposite end of the piston rod is connected to the end of a push rod which is, in turn, connected to a cylinder force transfer lever. This cylinder force transfer lever is connected through a series of force transmitting members and linkages so as to initiate a braking sequence and consequently apply the brake shoes to the vehicle wheels.
A disadvantage of this type of pneumatically activated brake cylinder is that, due to regulations regarding the amount of air pressure which must be supplied into the brake cylinder, it is sometimes difficult to control the movement and/or force applied by the piston. During light load conditions, too much force applied by the piston can cause the brake shoe forces to be greater than necessary resulting in wheel skid.
SUMMARY OF THE INVENTION
The invention comprises a brake cylinder for use in a railway vehicle braking system comprising a cylindrical casing engageable with the railway vehicle braking system. A hollow piston assembly which is mounted for reciprocal movement within the cylindrical casing. This hollow piston assembly has a hollow portion defined by a back wall and at least one sidewall. A small piston assembly is positioned within this hollow portion. The small piston assembly includes a first surface facing the back wall of the hollow portion and a peripheral edge portion for sealingly engaging an inner surface of the at least one sidewall of the hollow portion. A first space is defined by the back wall of the hollow portion, at least a portion of the inner surface of the at least one sidewall and the first surface of the small piston. Fluid communication means are provided which are in fluid communication with the first space for supplying fluid pressure within this first space during a brake application of the railway vehicle braking system resulting in movement of the hollow piston assembly away from the small piston assembly and for evacuating fluid pressure from the first space during a brake release of the railway vehicle braking system resulting in movement of the hollow piston assembly toward the small piston assembly. A piston rod assembly having a first end and a second end is provided. The first end of the piston rod assembly is connected with the hollow piston assembly and the second end of the piston rod assembly is engageable with the brake rigging of the railway vehicle such that movement of the piston rod assembly in an outward direction during a brake application initiates a braking sequence of the railway vehicle braking system.
OBJECTS OF THE INVENTION
It is an object of the present invention to provide a brake cylinder using dual piston assemblies with two sealing surfaces which allows for improved control of the movement of the brake cylinder piston and consequently improved control of the brake shoe forces.
It is a further object of the invention to provide a brake cylinder using dual piston assemblies which allows for a reduced amount of force to be applied to the brake cylinder piston during light load conditions.
It is yet a further object of the invention to provide a brake cylinder using dual piston assemblies which can readily supply sufficient force to the brake cylinder piston during full load conditions.
Although a number of objects and advantages of the present invention have been described in some detail above, various additional objects and advantages of the brake cylinder of the present invention will become more readily apparent to those persons who are skilled in the art from the following more detailed description of the invention, particularly, when such detailed description of the invention is taken in conjunction with both the attached drawing figures and with the appended claims.
REFERENCES:
patent: 3068841 (1962-12-01), Robbins et al.
patent: 3595348 (1971-07-01), Kyllonen
patent: 3779135 (1973-12-01), Sugimura
patent: 4033629 (1977-07-01), Spalding
patent: 4225193 (1980-09-01), Hart
patent: 4467605 (1984-08-01), Smith
patent: 4493246 (1985-01-01), Dailbout
patent: 4925618 (1990-05-01), Takada
patent: 5746293 (1998-05-01), Engle
James Ray & Associates
Oberleitner Robert J.
Sy Mariano
Westinghouse Air Brake Company
LandOfFree
Brake cylinder using dual piston assemblies does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Brake cylinder using dual piston assemblies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Brake cylinder using dual piston assemblies will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2439591