Railway car retarder

Details Railway car retarder Railway car retarder

1998-11-06

2001-04-24

Schwartz, Christopher P. (Department: 3613)

Brakes

Vehicle

Railway

C188S043000, C246S1820AB, C184S026000

Reexamination Certificate

active

06220400

ABSTRACT:

This invention relates to railway braking systems, and more particularly, to a low-profile pneumatically operated braking actuator for a hump-type railway car retarder system.
In railway classification yards, cars are separated from engines and sorted or classified based both on the type of car and the contents of the cars. In humptype classification yards, a series of side tracks are positioned on a sloped surface, leading downhill from the main track. Often, the tracks are also curved. As cars are separated from a train, each car is directed to a specific side track based on the type and content of the car, and is allowed to roll down the sloped surface. A railway car retarding system, generally comprising a frictional braking system having frictional braking members which engage and grip the sides of the passing wheels of the railway cars, is employed to slow and stop the cars on the sloped or curved side tracks.
In recent years, the design of railway cars has been modified in order to increase the load-carrying capacity of the cars. Increasingly, railway cars are being designed lower to the ground, such that the distance between the bed of the railway cars and the rails below is decreased.
Existing braking systems generally include pneumatic or hydraulic piston cylinder actuators which activate the frictional braking members. Generally, the frictional braking members are coupled to a support tube or other device which extends above and in close proximity to the adjacent rail. As the piston cylinder is activated, the motion of the support tube forces the frictional braking member towards the passing car.
The piston cylinder actuators of existing systems are typically controlled by a computerized control system, which activates the actuators, and determines the level of pressure to apply to a given car based on a number of factors such as rail grade, car type, car weight, and wind resistance.
To provide an effective retardation of the cars it is important that the frictional braking members be applied to the cars in a controlled and repeatable fashion. Pneumatic or hydraulic piston cylinder actuators, however, are problematic in this regard for several reasons. First, as noted above, in traditional hydraulic or pneumatic cylinder actuators, the frictional braking elements of the retarding system are pivoted about a point extending above the adjacent rail. When the retarding system is located at a comer, cars of the train may come into contact the with retarder system. The inadvertent contact between the car and the retarder system may cause damage to the train, the car retarder itself, or, in some cases, even derailment.
Secondly, a significant volume of fluid under pressure must be supplied to the cylinder of the actuator to activate the brake, and removed from the cylinder to deactivate the brake. A substantial time period is necessary, therefore, to activate and deactivate the frictional braking members. Furthermore, the fluid must be compressed to a relatively high pressure of about 16,500 pounds force to activate the piston cylinder actuator. Because of the high volume and pressure levels required to control the piston cylinder actuator, it is difficult to provide repeatable incrementally-controlled braking action. Generally, piston cylinder actuators provide on and off positions braking positions, and only a very limited range of intermediary “slowing” positions between. Therefore, when using pneumatic or hydraulic piston cylinder actuators, railway cars are not slowed to a controlled stop, but rather are stopped abruptly.
In addition, in piston cylinder actuators, a seal must be positioned between the movable piston and the cylinder. To assure that a vacuum is maintained between the piston and the cylinder, grease-based or graphite packing materials must be packed around the seal. The seals, however, wear with time and temperature, and may release hydraulic or other fluids into the ground around the actuator. Actuators of this type, therefore, pose an environmental problem for the classification yard. Moreover, the packing materials are very temperature sensitive and harden as the ambient temperature falls. Therefore, as the temperature falls, the amount of pressure required to move the cylinder increases, making it increasingly difficult to retard the cars, and increasingly difficult to accurately control the braking action of the frictional braking members.
It is therefore an object of the invention to provide a railway car retarder which does not interfere with railway car operations when placed at a comer of a classification yard.
It is therefore an object of the invention to provide a railway car retarder which can be activated and deactivated quickly.
It is another object of the invention to provide a railway car retarder which is activated by a relatively low volume of fluid at a relatively low pressure.
It is a further object of the invention to provide a railway car retarder which can be incrementally controlled to provide a wide range of braking levels.
It is yet a further object of the invention to provide a railway car retarder which operates consistently over a wide temperature range.
It is a still further object of the invention to provide a railway car retarder which is environmentally safe.
In one aspect, the present invention is a low-profile railway car retarder system, designed to prevent interference between the passing cars and the retarding system itself as the cars pass the retarder, and particularly where retarders are located at curves in the track. The low-profile car retarder system employs upper and lower levers which pivot about a fulcrum point under the rail itself. The levers are each coupled to an associated brake beam support and brake stop. The brake stops are applied to the passing railway car to stop the car. The levers and brake beam supports are all maintained at a level below the height of the adjacent rail. Therefore, all of the components of the retarding system are positioned to prevent inadvertent contact with passing cars. Furthermore, the levers are controlled by a bladder-activated braking actuator. The bladder-activated actuator is activated by a relatively low volume of compressed air or other fluids. Therefore, the bladder-activated braking actuator is smaller and has a lower profile than prior art systems.
In another aspect, the invention is a railway car retarder system with an improved control system. As noted above, the railway car retarder is activated by a braking actuator controlled by a bladder. The bladder is activated by a relatively low volume of compressed air or other fluids. The amount of pressure required to activate the bladder, therefore, is significantly lower than in prior art hydraulic devices. The bladder also operates at higher pressures, thereby providing a larger operating range than conventional methods. Furthermore, the bladder is not sensitive to changes in ambient, and can be repeatably controlled at any temperature. Additionally, the bladder is sealed on all sides, and does not require a lubricant. Therefore, the bladder braking actuator substantially eliminates the environmental problems often associated with the prior art.
Other advantages and features of the invention, together with the organization and manner of operation thereof, will become apparent from the following detailed description when taken in conjunction with the accompanying drawings wherein like elements have like numerals throughout the drawings.


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