DEVICE AND METHOD OF CONTROLLING OPERATING TOOL

PURPOSE: To minimize stress to the car body of a wheel loader at work in sudden stop of the bucket, by controlling up and down movement of the bucket based on a pilot signal selected depending on a position that the bucket passes during the work cycle and the position of a control lever. CONSTITUTION: In a control unit 10 around a hydraulic lift cylinder 18 which whirls the bucket 16 around a pivot pin 13 of a wheel loader 12, a detent mechanism 26 is attached to a control lever 24 that is springed toward the neutral position, and when a kickout signal is received from a controller 30, the control lever 24 is released under control from each detent position for up and down movement. Control of an electrohydraulic pilot supply valve 38 depending on the signal from the controller 30 controls respective flow of operating fluid to pilot valves 40, 42, feeds the operating fluid passed through the pilot valve 40, 42 to a main valve 48 through resolvers 44, 46 for up and down movement, and controls telescopic motion of a lift cylinder 18.