Abstract: The invention relates to a hydraulic drive system for the tool-bearing slide of a forging press or a forging machine. The slide is configured as a piston and is provided with a valve seat at the opposite end of the tool, that is, the end which is impinged upon by pressure means. Together with a valve lifter driven by an actuator, said valve seat forms a valve which is able to connect the cylinder chamber to a pressureless discharge pipe and therefore control the stroke of the piston. In order to reduce the mass and the axial construction length of the inventive drive system, the piston is hollow over a portion of its length from the end which is impinged upon, and is provided with the valve seat at the base of the hollow. The valve lifter, which can be axially displaced in the cylinder lid, is tubular in shape and is provided with side channels connecting its inner cavity to a pressureless discharge pipe for the pressure means.

Abstract: A multi-ram forging assembly has a piston-cylinder unit for driving each ram carrying a forging tool wherein at least two diametrically opposed forging unit simultaneously act on a workpiece. Each piston-cylinder unit comprises a pressurized inlet chamber for containing a hydraulic pressure fluid at a predetermined pressure behind a piston movably disposed in the cylinder. The piston includes a front-end ram carrying a forging tool. A valve including a valve seat member is disposed on the piston at a rear side opposite to the front-end ram. A valve cone cooperates with the valve seat member to provide a closed position and an open position for the valve. An actuator is connected to move the valve cone between the closed and open positions. The piston includes a passage bore extending from the valve seat member to a pressure fluid discharge chamber connected to a hydraulic pressure fluid reservoir container providing a pressureless discharge of the pressure fluid medium.