Abstract: A piston-and-ring assembly includes a piston having a circumferential groove which has an upper side wall and an opposite lower side wall; and a piston ring received in the groove and having opposite radial faces extending obliquely with respect to the side walls. The piston ring engages, with an axial bias, the upper and lower side walls with an annular marginal surface portion forming part of each radial face of the piston ring and extending substantially parallel to the side wall with which it is in engagement.

Abstract: A piston ring whose contour deviates from the circular shape, and in particular an elliptical or oval piston ring, which, when seen in the circumferential direction, has regions that, in the installed state as well as in the operating mode, exert less radial contact pressure than the remaining surface regions in order to reduce wear of and leakage by the ring.

Abstract: A cross-sectionally U-shaped radially inwardly open piston ring for a piston slidably received in a cylinder and dividing the cylinder into a high-pressure side and a low-pressure side. The piston ring includes first and second radially inwardly projecting, circumferentially extending legs for being received in respective grooves of the piston, while straddling a radially outwardly projecting, circumferentially extending web forming part of the piston. That leg which is closer to the high-pressure side than the other leg when the piston ring is in place on the piston, is resiliently deformable in a direction parallel to the axis of the piston in response to pressures prevailing at the high-pressure side, whereby the leg is circumferentially pressed against the web forming part of the piston.

Abstract: A piston ring formed of an annular, cross-sectionally bent metal strip has a series of circumferentially distributed slots extending in a generally axial orientation from edges of the strip. The slots are in an overlapping relationship when viewed circumferentially for defining a series of circumferential, resilient webs. The webs have web portions that are readily deformable to bending forces.