| 摘要 |
An apparatus for increasing an operation speed of a boom on excavators is disclosed, which enables an unskilled operator to conveniently manipulate a working device by decreasing a rotation speed and increasing a lifting speed relatively when the excavator performs combined operation of boom lift and swing drive to improve its working efficiency. The apparatus includes first and second hydraulic pumps, a first actuator, a pair of second actuators, first to third control valves, a block valve installed in a flow path between the selected second actuator and the second control valve, supplying the hydraulic fluid from a second hydraulic pump to the selected actuator only when the second actuators are driven to be switched according to a control signal of boom lift at combined operation in which the first and second actuators are simultaneously driven, to replenish the first actuator with the hydraulic fluid to be supplied to the second actuator.
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