| 摘要 |
PCT No. PCT/JP90/00357 Sec. 371 Date Mar. 16, 1991 Sec. 102(e) Date Mar. 16, 1991 PCT Filed Mar. 16, 1990 PCT Pub. No. WO90/10757 PCT Pub. Date Sep. 20, 1990.A parking brake circuit for a hydraulically driven vehicle which prevents the occurrence of an erroneous operation at the time when the vehicle travels on a downward slope. The parking brake circuit comprises first and second main circuits (2, 3) for supplying hydraulic operating fluid into a hydaulically driven motor (1) for traveling the vehicle. A counterbalance valve (4) provided between these main circuits for feeding hydraulic operating fluid on the side of high hydraulic pressure into a pressure receiving chamber (6a) of a parking brake actuating actuator (6). A conduit (5) for connecting an outlet port of the counterbalance valve to the pressure receiving chamber, and a slow return valve (12) are provided in the conduit so as to control a flow of hydraulic operating fluid directed from the pressure receiving chamber to the counterbalance valve.
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