CONTROL DEVICE FOR A WORK DEVICE COMPRISING A SCOOP HELD ON AN EXTENSION ARM

摘要

An extension arm (12) is rotationally maintained on a work device and a scoop (14) is rotationally maintained on the extension arm. The extension arm (12) and the scoop (14) are respectively actuated by a hydraulic cylinder (18,22). A valve (42,41) is associated with each cylinder (18, 22), enabling the flow of the pressure medium from one pump (28) to the cylinder (18,22) and therefrom to the tan (29) to be controlled. In order to ensure that the upper edge of the scoop (14) maintains the angular position thereof when the extension arm (12) is raised or lowered, the valves (42, 41) controlling the flow of the pressure medium to the cylinders can be controlled in such a way that the ratio (Q2, Q1) of the amounts of pressure medium fed to the cylinders (18,22) is kept to a constant value (KQ), independently from the size of the control signal controlling the flow of pressure medium to the cylinder (18) for actuation of the extension arm.