Patent ID: 6430922
Filing Date: 2002-08-13
Classification: E02F,F15B

Abstract:
A construction machine comprising:a rotating motor for causing a rotating operation of a part of the construction machine; actuators including an arm cylinder for causing operation of an arm of the construction machine; a plurality of hydraulic pumps; control valves positioned and adapted to control supply and discharge of oil between the hydraulic pumps and each of the actuators, said control valves including a control valve for the rotating motor and a control valve for the arm cylinder; a switching valve switchable between a first position and a second position, wherein the switching valve is positioned and adapted such that when the switching valve is in the first position the switching valve separately supplies oil from the hydraulic pumps to the control valve for the rotating motor and the control valve for the arm cylinder, and when the switching valve is in the second position the switching valve unites the oil from the hydraulic pumps; a detector adapted to output signals responsive to a rotating operation and an arm operation, respectively; a switching controller adapted to receive the output signals from the detector, and to switch the switching valve to the second position when signals responsive to a rotating operation and an arm operation are output substantially simultaneously; and a meter-in flow controller adapted to restrict a quantity of oil supplied to the arm cylinder when the switching valve is switched to the second position.