| 摘要 |
PROBLEM TO BE SOLVED: To allow an operator to securely sense a limit of excavation depth by a front work mechanism by operation reaction force of an operation lever when the depth is limited by it. SOLUTION: When a stroke sensor provided in respective hydraulic cylinders for driving a boom and an arm bucket is taken into a controller and a possibility of loss of stability of a vehicle is judged operation reaction force of an operation lever 10 is increased more than that at ordinary operation. Operation reaction force of the operation lever 10 is obtained by a return spring 33 and a spring for setting 34 acting on a pusher 30, and a spring seat 32 pushed and moved by the pusher 30 is constituted by a permanent magnet to increase reaction force of the operation lever 10 additionally. Moreover, an electromagnet 39 is arranged at outer periphery of a spool 26 to provide a reaction force generation means. Electricity is conducted into the electromagnet 39 based on a signal from the controller so that a magnetic field acts in the direction in which it repels for the permanent magnet constituting the spring seat 32.
|
