Abstract: Disclosed is a centrifuge including a rotationally mounted drum and a worm mounted therein in a concentric manner to rotate at a different speed therefrom. The drum and the worm are driven by a stationary motor unit. A hydraulic motor, provided with a housing and a rotor and fed by means of a hydraulic pump, is mounted therebetween. Such a centrifuge has the hydraulic feed pump assigned to the hydraulic motor to rotate along with the hydraulic motor while the rotor thereof is supported outside the rotating centrifuge parts to not rotate together with the rotating centrifuge parts. Additionally, the quantity of liquid delivered to the hydraulic motor by the feed pump is modified via displacement members actuated in a hydraulic fashion and disposed on the drive unit to rotate therewith.

Abstract: A hydrostatic piston-and-cylinder machine includes an array of cylinders and a piston movable in each cylinder, a sinuous cam track and a cam-follower associated with the pistons engaging the cam track in a manner such that the pistons move to and fro along the axes of their cylinders on movement of the cylinder array along the cam track. For the relief of stresses due to high mutual convexity of the cam and cam follower the cam is shaped to give a relatively low velocity change rate for the pistons along the cylinder bores when the cam follower is negotiating the crests of the cam and a relatively high velocity change rate when the cam follower is negotiating the troughs of the cam.

Abstract: A piston for a hydrostatic machine comprises a cam follower ball in a seating in a piston body. An aperture through the piston body provides access for working fluid to reach the seating to give lubrication and hydrostatic support. A low friction insert of synthetic plastics material in the seating provides a bearing surface for the ball. The insert is retained in the piston body by a lip which prevents or inhibits extrusion of the plastics material under working load pressure.