| 摘要 |
A parking brake system for use on a railway car includes an actuator which is adapted to be attached to a service brake actuating lever arm of the railway car and to receive a flow of non-compressible holding liquid from a reservoir through a first valve unit. The first valve unit permits the liquid to freely flow to and from the actuator in a first position and only permits flow of the liquid towards the actuator in a second position. With this arrangement, movement of the service brake actuating lever arm automatically causes the actuator to be supplied with holding liquid from the reservoir, which liquid can be selectively retained by shifting of the first valve unit to the second position. Furthermore in accordance with the invention, the actuator can be shifted by supplying pressurized holding liquid thereto through the use of a motor driven pump circuit including a pressurizable reservoir. In accordance with this embodiment of the invention, an additional valve is provided between the pressurizable reservoir and the actuator to selectively interconnect the pressurizable reservoir to the actuator. Various components of the system are preferably integrated into units which can then be interconnected. With such an arrangement, only minor attachments have to be made to retrofit an existing railway car with the parking brake system. Furthermore, the system can be incorporated in either static or pressurized modes of operation with the static system being readily convertible to a pressurized system.
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