Abstract: A piston head assembly has one, two or more grooves to receive piston rings. One or more of the grooves may receive multiple piston rings. A circumferential groove from the bottom of the elastomeric material allows oil pressure to aid in sealing. A novel piston ring employs a circumferential channel facing outwardly with a shorter bottom channel facing outwardly with a shorter bottom channel sidewall. The elastomeric material extends to form a circumferential extension cooperative with a subgroove of the piston ring groove.

Abstract: A piston head assembly has one, two or more grooves to receive piston rings. One or more of the grooves may receive multiple piston rings. One of the piston rings may have a wiper extension on the lower outside edge of the ring either of metal or elastomeric material. An elastomeric ring is retained preferably in a recess in the lower outer edge of the ring and has an outer surface starting inset from the top outer edge of the ring, but tapering to a diameter at least as great as the top outer edge. A circumferential groove from the outer edge. A circumferential groove from the bottom of the elastomeric material allows oil pressure to aid in sealing. A novel piston ring employs a circumferential channel facing outwardly with a shorter bottom channel facing outwardly with a shorter bottom channel sidewall. The channel is filled with elastomeric material providing at its outer surface a wiper member engaging the cylinder wall.