Abstract: An electrohydraulic drive unit is provided, comprising a cylinder-piston assembly having a piston-side first hydraulic working chamber and a piston-rod-side second hydraulic working chamber, a tank, a hydraulic pump, which can be driven at variable rotational speed and which has a tank connection point and a working connection point, a valve assembly, which is connected between the working connection point of the hydraulic pump and the cylinder-piston assembly, and an anti-cavitation valve, which is connected between the tank and the first hydraulic working chamber; and a machine controller. Switching valves of the valve assembly can be switched between loading of the first hydraulic working chamber and loading of the second hydraulic working chamber of the cylinder-piston assembly during pumping operation of the hydraulic pump from the working connection point of the hydraulic pump by the machine controller.

Abstract: In a machine press with a lower and an upper tool support, a closed hydraulic drive system acts upon the upper tool support. This system has at least one hydraulic drive unit, which includes at least one hydraulic cylinder-piston unit and at least one hydraulic assembly acting upon this unit and supplied from a storage reservoir. A base pressure above environmental pressure constantly prevails in the storage reservoir. The storage reservoir is designed as a cylinder store with a hydraulic chamber defined by a cylinder and a piston unit displaceably guided therein. The piston unit is acted upon on its side functionally opposite the hydraulic chamber by a hydraulic fluid chamber which for its part is connected to a high-pressure gas store. The active surface of the hydraulic fluid chamber on the piston unit is small compared to the active surface of the hydraulic chamber on the piston unit.

Abstract: An electrohydraulic drive unit is provided, comprising a cylinder-piston assembly having a piston-side first hydraulic working chamber and a piston-rod-side second hydraulic working chamber, a tank, a hydraulic pump, which can be driven at variable rotational speed and which has a tank connection point and a working connection point, a valve assembly, which is connected between the working connection point of the hydraulic pump and the cylinder-piston assembly, and an anti-cavitation valve, which is connected between the tank and the first hydraulic working chamber; and a machine controller. Switching valves of the valve assembly can be switched between loading of the first hydraulic working chamber and loading of the second hydraulic working chamber of the cylinder-piston assembly during pumping operation of the hydraulic pump from the working connection point of the hydraulic pump by the machine controller.

Abstract: In a machine press with a lower and an upper tool support, a closed hydraulic drive system acts upon the upper tool support. This system has at least one hydraulic drive unit, which comprises at least one hydraulic cylinder-piston unit and at least one hydraulic assembly acting upon this unit and supplied from a storage reservoir. A base pressure above environmental pressure constantly prevails in the storage reservoir. The storage reservoir is designed as a cylinder store with a hydraulic chamber defined by a cylinder and a piston unit displaceably guided therein. The piston unit is acted upon on its side functionally opposite the hydraulic chamber by a hydraulic fluid chamber which for its part is connected to a high-pressure gas store. The active surface of the hydraulic fluid chamber on the piston unit is small compared to the active surface of the hydraulic chamber on the piston unit.