A pressure-applying arrangement in a hydraulic axial piston machine is disclosed, having a pressure plate (7) and a piston (9) that is axially displaceable in a cylinder body (3), is biased by a spring (10) and acts against the pressure plate (7). It should also be possible to use such a pressure-applying arrangement when the axial piston machine is operated with a hydraulic fluid that has no or only very little lubricating property, for example, water. For that purpose, the piston (9) is formed from a high-strength thermoplastics material.

A spring-loaded piston is produced from plastic, particularly by injection molding. The spring-loaded piston is developed in the area of a connection to a piston or piston rod such that tilting of the spring-loaded piston with respect to the piston rod is prevented and a sufficiently firm connection is ensured. In addition, the spring-loaded piston 1 may include a reinforcing insert by which clearly higher forces can be transmitted while maintaining smaller wall thicknesses than in conventional spring-loaded pistons. Also, the seat or contact surface in the spring-loaded piston is constructed for supporting the preloaded spring such that possibly occurring radial forces do not have any negative influence on the functionality of the spring-loaded piston.

A piston is provided for use in a free-piston engine and includes a crown portion having a predetermined thickness, a plunger connection portion having a passage extending therethrough along the axis of the piston and being connected to the crown portion, a sealing portion extending from the crown portion, and a strut portion having a plurality of struts disposed between the sealing portion and the plunger connection portion. The piston of the subject invention provides a compact, high strength, low weight design that is effective in use to provide efficient operation and effectively conduct heat from the piston during use.

Pistons, which are reciprocated by a swash plate of a compressor, have two separate parts joined together. Each piston has a body and a coupler. The coupler is connected to the swash plate. The body is made of thermosetting resin. The body is molded to the coupler. Accordingly, the piston body to be firmly connected to the coupler.

An angulating piston assembly for a vehicle air conditioning system compressor comprises a composite piston including a metal rod having a ball at a proximal end and a plastic head at a distal end. A piston ring subassembly is operatively received about the periphery of the plastic piston head. The subassembly is characterized by a rigid support collar molded into the piston head and a piston ring of low friction material stretched and snugly received over the collar. An integral molded lip on the piston head and an outwardly projecting skirt on the support collar maintain the piston ring in position. An inwardly projecting flange is provided on the support collar and molded into the plastic piston head to provide a lock to prevent relative axial movement between the support collar and the piston head. A method of forming and assembling an angulating piston assembly includes the steps of: 1) mounting the piston ring on the rigid support collar; 2) placing the piston ring subassembly into a mold cavity; 3) positioning a distal end of a piston rod to extend into the mold cavity; 4) closing the mold cavity; 5) injecting molten plastic into the cavity to form the piston head; and 6) separating the mold cavity and removing the assembly.