Patent ID: 6016739
Filing Date: 2000-01-25
Classification: F04B,F16J

Abstract:
A piston for reciprocating and simultaneously rotating through a predetermined length of movement within a piston bore having a piston bore surface, the piston comprising:a substantially cylindrical member having first and second extreme portions, a central portion and first and second ends, the central portion having a known length and a constant diameter over the known length, the first and second ends having equal known diameters, the first extreme portion extending from the first end to the central portion, the second extreme portion extending from the second end to the central portion, the first extreme portion having an extended curvature reducing the diameter of the cylindrical member from the diameter of the central portion to the diameter of the first end, the second extreme portion having an extended curvature reducing the diameter of the cylindrical member from the diameter of the central portion to the diameter of the second end, each extended curvature being convex in nature and providing continuous, tangential cooperation between the extreme portions of the cylindrical member and the piston bore surface within the predetermined length of movement to reduce wear on the piston bore surface, each extreme portion being equal in length and shorter than the central portion, the length of the central portion being less than the diameter of the first and second ends.