| 摘要 |
PCT No. PCT/JP97/01057 Sec. 371 Date Aug. 13, 1998 Sec. 102(e) Date Aug. 13, 1998 PCT Filed Mar. 27, 1997 PCT Pub. No. WO97/36062 PCT Pub. Date Oct. 2, 1997A braking apparatus for a hydraulic motor (20) having a rotary component (21) includes a rotary side friction plate (22) coupled to the rotary component of the hydraulic motor, a fixed side friction plate (23) coupled to a fixed component of the hydraulic motor, and a braking cylinder assembly (24) having a piston (25), a spring (26) and a piston pressure receiving chamber (27). The piston is energizable by the spring to move in a braking direction for bringing the fixed side and the rotary side friction plates into a pressure contact, whereas the piston pressure receiving chamber can be be supplied with pressure fluid to displace the piston in a braking release direction, thereby separating the fixed side friction plate and the rotary side friction plate from each other. An operating valve (41, 42) supplies pressure fluid into the hydraulic motor, and a hydraulic pilot valve (52, 53) provides pilot pressure fluid for use to switch the operating valve. A pilot pressure fluid from the hydraulic pilot valve is delivered through a hydraulic circuit (28) into the piston pressure receiving chamber. The braking apparatus further includes in the hydraulic circuit a fluid flow control valve (30) which has an area of valve opening progressively reduced as a function of a distance of travel of the piston moving and displaced from a braking position towards a braking release position.
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