A reciprocating-piston machine, in particular a two-stage or multi-stage piston compressor, includes: a first connecting rod for deflecting a first piston and which has a connecting-rod eye, the first connecting rod being a drive connecting rod; a second connecting rod for deflecting a second piston and which has at least one further connecting-rod eye, the second connecting rod being a follower connecting rod; a coupling element which extends through the connecting-rod eye and the at least one further connecting-rod eye and about which the first connecting rod and the second connecting rod are rotationally movable relative to one another; a coupling bearing element arranged between the coupling element and a connecting-rod eye inner surface of the connecting-rod eye; and a damping element with elastic damping action arranged in a damping annular chamber between the coupling bearing element and the connecting-rod eye inner surface of the connecting-rod eye.

A fluid compressor includes a housing; a compression chamber within the housing; a motor; a shaft that is rotated by the motor; and a piston assembly including at least two pistons directly connected to each other without any connecting rods. The piston assembly performs a reciprocating motion when acted on by the shaft such that the at least two pistons move within the compression chamber to compress a fluid.

A piston cylinder arrangement for an air compressor including a cylinder, a connecting rod having a wrist pin receiving end, a wrist pin provided in the wrist pin receiving end of the connecting rod, and a piston provided on the connecting rod via the wrist pin and positioned within the cylinder. At least one passageway may be defined in the wrist pin to permit air to flow into the wrist pin from the cylinder.

A gas compressor includes an incompressible fluid source for storing an incompressible fluid. A rotary shaft is coupled to the incompressible fluid source. Operation of the rotary shaft draws the incompressible fluid up or down the rotary shaft. A piston chamber is coupled to each piston in a set of pistons. The incompressible fluid is delivered to the first piston by a controlled fluid valve assembly, to drive the first piston. The centripetal force from the rotation of the rotary shaft and the force of incompressible fluid from an impeller drive the first piston to compress a gas in the piston chamber of the first piston. The incompressible fluid is released from the first piston, by the controlled fluid valve assembly. The incompressible fluid is alternately delivered to the second piston to drive the second piston and compress gas.

A piston drive device includes: a crankcase; first and second compression cylinders fixed to the crankcase; first and second vacuum cylinders fixed to the crankcase; a rotational shaft rotatably supported within the crankcase; first and second compression pistons connected to the rotational shaft and reciprocating respectively within the first and second compression cylinders; and first and second vacuum pistons connected to the rotational shaft and reciprocating respectively within the first and second vacuum cylinders; wherein each diameter of piston heads of the first and second compression pistons is smaller than each diameter of piston heads of the first and second vacuum pistons, and the first and second compression pistons are connected to the rotational shaft so as to sandwich the first and second vacuum pistons in an axial direction of the rotational shaft.

A cam driven compressor includes a cam coupled to a plurality of cylinder and piston assemblies. Each cylinder and piston assembly comprises a piston located and movable within a respective cylinder. Each cylinder has a cylinder head. The compressor comprises a housing defining a cavity configured to receive a portion of a source gas from one or more of the cylinders in order to maintain a positive gas pressure within the cavity.

A radial piston machine includes a piston having a base which is provided with a roller. The roller is held secure by a bearing shell that is inserted in the piston base.