Mattingly & Malur, PC
Hydraulic system for working machine
A hydraulic system for a working machine is provided in which when heavy load fine speed operation work is performed using hydraulic cylinders as hydraulic actuators, and deterioration of fuel consumption can be prevented by reducing energy loss and improving fine speed operability. A center bypass cutoff valve 41 is disposed downstream of a center bypass line 26, and pressure sensors 42, 43, a controller 44, and a solenoid valve 45 provide control such that, when operating means 16 corresponding to a boom cylinder 5 (specific hydraulic actuator) among a plurality of operating means 18-21 is operated to supply a hydraulic fluid to a cylinder chamber 5a of the boom cylinder 5 in a load retaining side, the center bypass cutoff valve 41 is actuated and a fluid delivery pressure of a first hydraulic pump 2 is increased to be higher than a load pressure of the boom cylinder 5. 
HITACHI CONSTRUCTION MACHINERY CO., LTD.
E F E E F F E F E F F E E F
E02F F15B E02F E02F F15B F15B E02F F15B E02F F15B F15B E02F E02F F15B
inventional inventional inventional inventional additional additional inventional additional inventional additional additional inventional inventional additional
Yuta Hidetoshi Katsuaki
Nakamura Satake Kodaka