Abstract: An apparatus to cushion movement of a member in a machine includes a piston which divides a cylinder into upper and lower variable volume chambers. A body of lubricating liquid is held in a chamber in the piston. Lubricating liquid is conducted from the chamber in the piston to an annular space between upper and lower seals on a head portion of the piston. During reciprocation of the piston, the lubricating liquid engages the inner side surface of the cylinder. In addition, the lubricating liquid conducts heat away from the cylinder. Fluid pressure is applied against upper side surface of the body of lubricating liquid in the piston chamber by gas pressure conducted from a chamber of the cylinder. During assembly of the apparatus, the piston is inserted part way into the cylinder and a space between seals on the piston is partially filled with lubricating liquid. The piston, with the lubricating liquid between the seals, is fully inserted into the cylinder.

Abstract: A die cylinder assembly is designed for use in an environment which has contaminants outside the assembly. The die cylinder assembly includes a piston disposed in a cylinder and having an outer end surface. The piston is moved in one direction by forces applied to the outer end surface of the piston. The piston is moved in an opposite direction by a working fluid pressure in a head end chamber of the cylinder. The cylinder includes a rod end variable volume chamber which is connected in fluid communication, through a first passage in the piston rod, with a third chamber located in the piston rod. The fluid pressure in the rod end chamber is always maintained at least as great as ambient fluid pressure to prevent contaminants from entering the rod end chamber. A check valve in a second passage admits outside air to the third chamber when fluid pressure in the third chamber drops below ambient pressure. A relief valve vents the third chamber if fluid pressure therein becomes too high.