HYDRAULIC CIRCUIT FOR CONSTRUCTION MACHINE

摘要

Disclosed is a hydraulic circuit for a construction machine, for preventing the loss of pressure at the time of complex work. A hydraulic circuit for a construction machine, according to the present invention, comprises: variable displacement type hydraulic pumps; at least two hydraulic actuators driven by a hydraulic fluid supplied from the hydraulic pumps; control valves respectively provided to the center bypass paths of the hydraulic pumps and controlling the initiation, suspension and direction conversion of the hydraulic actuators at the time of conversion; parallel paths of which inlets are branched and connected to predetermined positions at the uppermost sides of the center bypass paths and outlets are respectively connected to the inlet ports of the control valves; bleed-off paths provided to the control valves excluding the control valve at the lowermost side of the control valves so as to selectively communicate with the center bypass paths, wherein the bleed-off paths communicate with the center bypass paths at the time of the conversion of the plurality of control valves so as to carry out complex work; and a conversion valve provided at the lowermost side of the center bypass paths and blocking the center bypass paths when a pilot signal pressure is applied.