| 摘要 |
PROBLEM TO BE SOLVED: To reduce co-rotation resistance caused by a cooling oil under low temperature to improve efficiency in free fall operation in spite of a wet type brake system, while a brake is forcibly cooled by the cooling oil. SOLUTION: In this winch, an oil temperature sensor 47 detects a temperature of the cooling oil led in the brake 13, and a selector valve controller 45 changes over a selector valve 46 to on-load a master valve 42 of a pressure control valve 41 when the oil temperature falls to a heating-necessary temperature range. Thereby, the cooling oil is pressurized to raise the temperature.
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