Patent ID: 7562525

Claim:
A hydraulic system for utility vehicles, in particular agricultural tractors, for supplying one or more primary pressure medium consumers ( 6 ) with pressure medium via one or more first slide valves ( 17 ) and one or more auxiliary pressure medium consumers ( 11 , 12 ) with pressure medium via one or more second slide valves ( 23 ), the system comprising a pump ( 1 ) sucking from a pressure medium tank ( 3 ), the pressure of said pressure medium being controlled as a function of the load pressure of the pressure medium consumers and supplying a pump pressure exceeding the load pressure by a predetermined control pressure differential, whereby in order to produce a first control pressure differential for operating primary pressure medium consumers ( 6 ) the pump load pressure acts upon a pressure and flow controller ( 13 ) assigned to the pump and in order to produce a second higher control pressure differential for operating auxiliary pressure medium consumers ( 11 , 12 ) a pressure exceeding their load pressure is produced by means of an amplifying circuit ( 29 ) in which two orifices ( 32 , 31 ) and a pressure regulator ( 33 ) are arranged in a line ( 34 ) which supplies fluid from the pump to the second slide valve ( 23 ), the pressure regulator ( 33 ) being operated in the opening direction by the load pressure of an auxiliary pressure medium consumers ( 11 , 12 ) and the increased pressure in the line between the orifices acting upon the pressure and flow controller ( 13 ), the load pressure of a primary pressure medium consumer ( 6 ) and the pressure supplied by the amplifying circuit ( 29 ) being fed via a shuttle valve ( 19 ) to the pressure and flow controller ( 13 ) of the pump ( 1 ), and a load pressure reporting line ( 28 ) conducting the load pressure of an auxiliary pressure medium consumers ( 11 , 12 ) to the pressure medium tank ( 3 ) via a flow control valve ( 30 ).