Patent ID: 7134380

Claim:
A valve arrangement for controlling a hydraulic drive, the supply and the outflow of the hydraulic drive being separately controllable, the valve arrangement comprising: a pump pipe; a tank pipe; a first control valve connected with the pump pipe and the tank pipe; a second control valve connected with the first control valve; a third control valve connected with the first control valve; a first working connection of the hydraulic drive connected with the second control valve; a second working connection of the hydraulic drive connected with the third control valve; at least one backflow preventer for preventing flow from the hydraulic drive in the direction of the tank pipe, the at least one backflow preventer being connected in parallel with one of the second control valve and the third control valve; and at least one electronic device for controlling the control valves; wherein the electronic device is adapted to operate the valve arrangement in at least one of the following modes by controlling the control valves: a control of supply pressure and outflow amount mode; a control of supply amount and outflow pressure mode; and a controlled returning of hydraulic fluid from one working connection to the other working connection mode.