| 摘要 |
PROBLEM TO BE SOLVED: To provide an inexpensive hydraulic device for an industrial vehicle, reducing the number of motors corresponding to the number of pumps while maintaining high cargo handling performance. SOLUTION: The hydraulic device comprises a cargo handling sub-pump 19 to be driven by the motor M2, a cargo handling main pump 18 to be driven by a motor M1 and a power steering pump 20, the pump 18 and the pump 20 being tandem connected to form a two-motor three-pump system. The motor M1 is started all times with key-on operation and the motor M2 is started only when high power is required. At starting operation, a discharge oil from the pump 20 is supplied to a powder steering system and a braking system hydraulic circuit and a discharge oil from the pump 18 is utilized for a pilot pressure on lift unlocking circuits 43, 44. During operation, the operating frequencies and output values of the motors M1, M2 are controlled depending on the working condition of the forklift 1, thus reducing the number of the motors corresponding to the number of the pumps while maintaining high cargo handling performance.
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