Piston ring

Claim 1

In a cross-sectionally U-shaped, radially inwardly open piston ring for a piston slidably received in a cylinder; the piston ring having an axis and including first and second radially inwardly projecting, circumferentially extending legs having outer circumferential ends; said piston ring further including an annular connecting portion joining said legs at said outer circumferential ends; the improvement wherein said legs are, in course and dimensions, symmetrical to one another relative to a central radial plane of the piston ring; said central radial plane extending perpendicularly to said axis of said piston ring; further comprising means defining a circumferential recess in a radially outer circumferential zone of said first leg near said annular connecting portion for rendering said first leg resiliently swingable in a direction parallel to the axis of the piston ring, so that when said piston ring is in place on said piston, with said legs received in respective grooves of the piston while straddling a radially outwardly projecting, circumferentially extending web forming part of the piston, said first leg is circumferentially pressable against said web by pressures prevailing at said high-pressure side.