An outer circumferential surface of a piston ring has a cut surface forming a notched portion between an outer circumferential end surface and a lower surface, the cut surface including a first surface between the outer circumferential end surface and a bo...

A combination of piston rings assembled to a piston includes a first compression ring, a second compression ring, a third compression ring and an oil ring. When an axial width of the first compression ring is h1(1), an axial width of the second compression...

A piston ring which is provided with a carbon-based coating which has a low friction property and wear resistance, that is, a piston ring which has a carbon-based coating formed over its sliding surface, in which piston ring, the coating is a multilayer co...