| 摘要 |
PROBLEM TO BE SOLVED: To improve the operability of a hydraulic winch by reducing both operational quantity and operating force for brake operation at the time of free fall work. SOLUTION: A positive side oil chamber 11a of a brake cylinder 11 for controlling brake actuation is connected to a tank T and an oil pressure source 18, via an electromagnetic proportional type pressure reducing valve 24 controlled by a controller 29, while a negative side oil chamber 11b is directly connected to the oil pressure source 18, and the operating force of a pedal 26 is adopted as the pressure of an operation cylinder 27 to be taken into the controller 29 to indirectly control the secondary pressure of the pressure reducing valve 24.
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