| 摘要 |
PROBLEM TO BE SOLVED: To provide a device for controllably positioning of a working appliance of an earth working machine. SOLUTION: The working appliance has a boom and an attachment fitted to the boom, the boom is operated by a hydraulic lift cylinder, and the attachment is operated by a hydraulic tilt cylinder. An appliance position sensor detects the elevating/lowering position of the boom and the turning position of the attachment, and generates each appliance position signal according thereto. A control device to receive the appliance position signal compares the relative position of the boom and the attachment with the predetermined boundary condition, and generates the electric valve signal. A valve assembly receives the electric valve signal, and the flow rate of the hydraulic fluid is fed controllably to each hydraulic cylinder according to the magnitude of the electric valve signal. |
