Patent ID: 7530225
Filing Date: 2009-05-12
Classification: E02F,F15B

Abstract:
1. An apparatus for increasing an operation speed of a boom on excavators, comprising: first and second hydraulic pumps; a first actuator connected to the first hydraulic pump; a pair of second actuators connected to the second hydraulic pump and connected in series to each other; a first control valve installed in a flow path between the first hydraulic pump and the first actuator, which functions to control startup, stop, and turnabout of the first actuator; a second control valve installed in a flow path between the second hydraulic pump and the second actuators, which functions to control startup, stop, and turnabout of the second actuators; a third control valve installed in a flow path between the second hydraulic pump and the first actuator, which functions to join a part of a hydraulic fluid of the second hydraulic pump into the first actuator; and a block valve installed in the flow path between the second actuators and the second control valve, supplying the hydraulic fluid from the second hydraulic pump to one of the second actuators to be selected 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.