In a hydraulic drive of a tool piston in a cylinder first and second flat contact areas each are contiguous, when moving into and in the open position of the valve member between the detent element and the valve member, wherein a pressure-limiting valve that can be loaded with the pressure in the cylinder from a closed position to an open position and a detent element loaded by a spring in the locking direction to positively hold a neck of a valve member of the pressure-limiting valve are arranged in the open position, wherein the detent element at least via the tool piston at its return to a released position can be moved and, when moving the valve member to the open position of the pressure-limiting valve, non-positively acts on the valve member.

A hydraulic drive including a differential cylinder that has a first pressure chamber and a second pressure chamber and a differential piston, a first hydraulic pump that includes a pump intake and a pump outlet, a directional control valve having a first switching position and a second switching position, a high pressure tank, and an additional hydraulic cylinder that includes an additional pressure chamber hydraulically connected with the pump intake and with the high pressure tank and an additional piston limiting the additional pressure chamber, the differential piston being movably coupled with the additional piston, wherein in the first switching position of the directional control valve the first pressure chamber is hydraulically connected with the second pressure chamber, and in the second switching position of the directional control valve the second pressure chamber is not hydraulically connected with the first pressure chamber.

In a hydraulic drive of a tool piston in a cylinder first and second flat contact areas each are contiguous, when moving into and in the open position of the valve member between the detent element and the valve member, wherein a pressure-limiting valve that can be loaded with the pressure in the cylinder from a closed position to an open position and a detent element loaded by a spring in the locking direction to positively hold a neck of a valve member of the pressure-limiting valve are arranged in the open position, wherein the detent element at least via the tool piston at its return to a released position can be moved and, when moving the valve member to the open position of the pressure-limiting valve, non-positively acts on the valve member.