| 摘要 |
PROBLEM TO BE SOLVED: To reduce loss of a hydraulic pump as much as possible, while using the actuator at a most appropriate speed, further to unload the engine during startup. SOLUTION: In this hydraulic unit, an engine 4 drives a hydraulic pump 3, and the hydraulic pump 3 supplies hydraulic oil to an actuator 1 for working unit, etc. This hydraulic unit is further equipped with an electric motor 8 for driving the hydraulic pump 3. Driving of the hydraulic pump 3 by the engine 4 and the driving of the hydraulic pump 3 by the electric motor 8 are to be switched over. Moreover, an assist pump is provided for supplying hydraulic oil to the actuator 1, with an electric motor to drive the assist pump.
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