the control valve 2 interrupts the flow and the control valves 5 6 and 7 are open thus the working connections a and b are connected with each other and with the tank 4 so that the low tank pressure rules at both working connections a and b another operation mode for example in connection with a jerk like pulling movement is achieved in that the cylinder position of the hydraulic drive 1 is controlled and a pressure relief is provided such an operation mode for example occurs in a tractor particularly when controlling the toolbar of a tractor which carries for example a plough for controlling the cylinder position when lifting a load l hydraulic fluid is supplied to the hydraulic drive 1 at the working connection a and when lowering a load l hydraulic fluid is returned to the working connection b from the working connection a via the control valves 5 and 6 a pressure control keeps the pressure p b under a certain pressure level by means of the control valve 7 the control valve 2 supplies hydraulic fluid to the hydraulic drive 1 which keeps the pressure p a at a lower level to prevent cavitation for this.