Patent ID: 8671824

Claim:
A hydraulic control system for supplying pressure fluid to at least one consumer ( 2 , 4 ), comprising: an electrical control unit ( 6 ); and an electric or electrohydraulic continuously adjustable valve device ( 18 , 20 ) via which it is possible to connect a supply-side pressure chamber of the consumer ( 2 , 4 ) to a pump ( 20 ) and to connect a return-side pressure chamber of the consumer ( 2 , 4 ) to a tank ( 24 ), wherein the valve device has a first load lowering valve ( 72 , 74 ) disposed in a supply line ( 64 , 66 ) connecting the supply-side pressure chamber with the pump ( 22 ); a second load lowering valve ( 72 , 74 ) situated in a return line connecting the return-side pressure chamber with the tank ( 24 ) and which is acted on in the direction of its opening position by the pressure in the supply line ( 64 , 66 ); a first continuously adjustable directional control valve ( 68 , 70 ) that is situated in the supply line ( 64 , 66 ) between the first load lowering valve ( 72 , 74 ) on the one hand and the pump ( 22 ) and the tank on the other hand and by means of which the connection of the supply-side pressure chamber with the pump ( 22 ) and with the tank ( 24 ) is controlled; and a second continuously adjustable directional valve ( 70 , 68 ), which is disposed in the return line ( 66 , 64 ) between the second load lowering valve ( 74 , 72 ) on the one hand and the pump ( 22 ) and the tank ( 24 ) on the other hand and by means of which a connection of the return-side pressure chamber with the pump ( 22 ) and with the tank ( 24 ) is controlled, wherein the first and second directional valves ( 68 , 70 ) have an open neutral position, in which the first and second load-lowering valves ( 72 , 74 ) are connected with the tank ( 24 ) and wherein the first directional valve ( 68 , 70 ) or the second directional valve ( 70 , 68 ) are actuatable by the control unit ( 6 ) from the neutral position, such that one of the first and second load lowering valves ( 72 , 74 ) is connected with the pump ( 22 ) and the other of the first and second lower valves ( 70 , 68 ) is connected with the tank ( 24 ), and wherein both first and second directional valves ( 68 , 70 ) are actuatable simultaneously from the neutral position, such that both the first and second load-lowering valves ( 72 , 74 ) are connected with the pump ( 22 ).