| 摘要 |
A hydraulic circuit having a holding valve of an external pilot pressure operation type is provided, which can make a double check valve (6), which is installed to prevent an actuator (1) from being pushed due to leakage of hydraulic fluid of a main control valve (2), be opened by an external signal pressure being supplied to shift the main control valve (2). The hydraulic circuit includes a hydraulic pump (P) connected to an engine and a pilot pump (Pp), a hydraulic cylinder (1) connected to the hydraulic pump (P) to expand and contract when hydraulic fluid is supplied thereto, a main control valve (2) installed in a flow path between the hydraulic pump (P) and the hydraulic cylinder (1) and shifted to control a start, a stop, and a direction change of the hydraulic cylinder (1), a joystick (11) outputting a pilot signal pressure from the pilot pump (Pp) in accordance with an amount of user's manipulation thereof, a double check valve (6) installed in a flow path between the main control valve (2) and the hydraulic cylinder (1) to be opened by the pilot signal pressure for shifting the main control valve (2), and preventing the hydraulic cylinder (1) from being moved due to leakage of hydraulic fluid of the main control valve (2), and a select valve (7) shifted to open the double check valve (6) in response to the pilot signal pressure being supplied in accordance with the manipulation of the joystick (11). |
