Abstract: A piston for a striker is displaceable in a cylinder and forms compartments on opposite sides which can selectively be connected by hydraulically controlled valve elements to a pump and to an accumulator. A hydraulic controller for the valve elements initially connects a compartment on one side of the piston to contribute the pressure from a respective compartment to the accumulator during a lifting operation, cuts off the valve element affording this pressure accumulation to brake the piston, and other such valve elements enable the accumulator to be charged with the piston in its raised position so that, upon triggering by the controller of the valve elements, the pressure which drives the ram is equal to the total pressure delivered by the accumulator and the pump to the piston.

Abstract: There is disclosed a hydrostatic motor provided with radially arranged hydraulic cylinders provided with radial pistons composed of pairs of pistons with different diameters fitted one into the other. The motor is selectively operable in either of two operating conditions, in a first of which the large and small pistons move as a unit in a heavy duty operation, and in a second of which only the small pistons move in a low duty operation. The motor includes a rotor and a stator, duct means arranged in the stator for the supply of pressure fluid to the pistons, a change-over unit within the motor, and a fluid distributor unit housed in the stator. The motor of the invention employs virtually the same distributing circuits during its operation in both its heavy duty and its low duty modes of operation.