Abstract: The invention provides a pulley that can prevent the rusting of an insertion member without using expensive heat resistant plating treatment and effectively prevent the slippage between a pulley main body and an insertion member. That is, the pulley main body 10a is integrally formed by the injection molding of synthetic resin on the outer circumferential surface side of the insertion member 11b in which painting having rust preventive properties and heat resistant properties is applied to at least part of surfaces including the outer circumferential surface. Therefore, the rusting of the insertion member 11b can be effectively prevented and besides even when the interior of a mold during injection molding comes to a high temperature state, the painting applied to the surface of the insertion member 11b will not deteriorate due to the high temperature and the corrosion resistance of the insertion member 11b will not be decreased.

Abstract: A refrigerant compressor includes a piston with two circumferential grooves on the outer surface of the piston, one of the grooves being located near the top and the other near the bottom. Conical piston rings made of plastic are disposed in the grooves. The piston rings, which have an outer diameter greater than that of the piston, have a curved surface shaped so that the outer diameter of the curved surface at one axial end of the piston ring is smaller than that at the other axial end. This unique arrangement of the curved conical seals reduces the loss of horsepower in motor driven refrigerant compressors by providing improved sealing between the piston and cylinder.

Abstract: A piston assembly for a reciprocating piston type compressor includes a piston slidably disposed within aluminum alloy cylinders. The pistons have two annular grooves provided toward opposite ends on their outer peripheral surfaces. A conical shaped piston ring formed of resin and having an outer diameter larger than the outer diameter of the piston is disposed in each groove. The conical shaped piston ring creates a gap between the piston and cylinder to prevent direct contact between the piston and cylinder to thereby avoid abnormal wearing while effectively maintaining the flow of lubricating oil from the cylindrical chamber to the crank chamber.