Piston ring

A combination of a piston and a mounted piston ring for a piston/cylinder unit, the piston having a circumferential surface with a height, a first top side and a second top side, the mounted piston ring covering the circumferential surface of the piston and sealing it off from the cylinder, the mounted piston ring comprising:

• a width greater than the height of the circumferential surface and forming an axially projecting length of the piston ring relative to the piston;
• a first spring end formed by the axially projecting length and being axially supported on and bearing against said first top side of the piston, said first spring end having a circular-arc-shaped transition in a range of 90°-180°;
• a second spring end forming an annular bearing surface bearing against a region of said second top side of the piston, said second spring end having a shaping angle adapted to a second angle between the circumferential surface and the second top side;
• and
• a pressure ring disposed between said circumferential surface of the piston and the piston ring, said pressure ring prestressing the piston ring radially against a cylinder wall to be sealed.