Patent attributes
The present invention overcomes drawbacks whereby the supply of pressure oil to a hydraulic cylinder for operating a ground working device is temporarily cut, and operation of the ground working device is temporarily stopped when a control valve for the travel device is operated while a control valve for the ground working device is being operated. When control valves (V4, V5) for the travel devices are operated during operation of control valves (V6, V7, V8) for the ground working device, and a first flow channel switching valve (V12) is switched from an operating position (31) to a travel position (34), a second flow channel switching valve (V13) is switched from a non-feeding position (39) to a feeding position (40) before or at the same time as the first flow channel switching valve (V12).
