Piston for a hydrostatic cylinder block

Abstract

A piston for use in the cylinder block of a hydraulic power unit. The piston has an elongated cylindrical body and one end terminating in a spherical surface. The piston is composed of a body and insert which are made from different materials, preferably metallic materials, and joined together. The piston body takes the form of a solid cylinder or a hollow cylindrical tube. The spherical surface takes the form of an internal spherical socket or an external spherical ball. The insert takes an elongated or abbreviated form providing for both open cavity and closed cavity piston configurations. The piston includes a conduit which traverses the body and insert, providing a path for pressurized fluid. The body and the insert are preferably formed by a metal injecting molding process utilizing a molding material comprised at the time of molding of a mixture of metallic grains and a binder. The body member and the insert are subjected to a debinding process whereupon the binder material is removed from the molding material and the components are sintered whereupon controlled shrinking occurs. The insert is adapted to terminate either in a spherical ball for attachment to a slipper element, or is comprised of a spherical socket adapted to receive a ball element attached to a slipper element.