Patent ID: 7607381

Claim:
A control device for a work appliance in which a shovel is held on an extension arm, in particular for a wheeled loader, comprising: two hydraulic cylinders, of which the first actuates the extension arm and the second actuates the shovel; a pump supplying the cylinders with pressure medium from a tank; two valves, of which the first valve controls the supply of pressure medium from the pump to the first cylinder and the second valve controls the supply of pressure medium from the pump to the second cylinder, each valve being provided with a spool having a surface acted upon by an adjustable control pressure counter to the force of a spring and being provided with a notch which runs in its longitudinal direction and determines the size of the passage cross section of the valve and which is formed in such a way that the respective passage cross section of the valve is determined by the position of the spool; two pressure compensators of which one is arranged downstream of the passage cross section of the one valve and the other downstream of the passage cross section of the other valve and which are acted upon in the closing direction by the highest load pressure and in the opening direction by the pressure downstream of the assigned passage cross section, whereby the valves can be activated in such a way that the ratio of the pressure medium quantities supplied to the two cylinders is held at a constant value independently of the size of the control pressure supplied to the first valve; whereby a desired motional relationship between those parts of the equipment that are moved by the two hydraulic cylinders is maintained even in the event of an undersaturation condition.