| 摘要 |
PROBLEM TO BE SOLVED: To provide a driving circuit constituted further compactly in a simple structure for a cooling fan for supplying cooling air to a cooler such as a radiator or an oil cooler provided at an industrial vehicle such as a construction machine. SOLUTION: The driving circuit for the cooling fan includes: a hydraulic motor 13 with the cooling fan 12 fixed to an output shaft; a variable displacement hydraulic pump 5 including a discharge quantity control part 5a controlling the discharge quantity of an operating fluid, and sucking the operating fluid from the operating fluid tank 15 to discharge the operating fluid; a pump discharge passage 31 reaching the hydraulic motor 13 from the hydraulic pump 5; a return passage 34 reaching the operating fluid tank 15 from the hydraulic motor 13; a branch passage 41 formed branching from the pump discharge passage 31 and reaching the operating fluid tank 15; a throttle 51 and a pressure control valve 52 provided in the branch passage 41; and a discharge quantity control pressure supply passage 42 connected between the throttle 51 and the pressure control valve 52 of the branch passage 41 to supply discharge quantity control pressure to the discharge quantity control part 5a. COPYRIGHT: (C)2011,JPO&INPIT
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