Attitude manipulation structure null of anti- area job

摘要

PURPOSE:To make possible to perform manual posture-changing operation of ground working machine without hindrance by separating automatic control valve and manual valve and constructing specific oil path. CONSTITUTION:Second control valve 22 for manual operation is installed between hydraulic cylinder 7 and first control valve 21 for automatic operation. An automatic operating position allowing oil discharge of second oil path 27, an expansion operating position communicating only the second oil path to hydraulic cylinder and a contraction operating position are installed in the second control valve. Expansion operation of the hydraulic cylinder is performed by only supplying and discharging of hydraulic oil from the first control valve in a case of operation of the second control valve at automatic position. In a case of operation of the second control valve in expansion operating position or contraction operating position, the second oil path from excess flowing port 13b of flow priority valve 13 is connected to the hydraulic cylinder and operation of the second control valve is not caused any hindrance by operation of the first control valve in manual operation.