To shorten a piston assembly and improve the strength of mechanical connection while keeping a high capacity output by fixing the spherical ball of a sliding body into the cavity of a piston, and aligning its outer surface to the outer surface of a piston body in the longitudinal direction, and hardening it over the full length.
A sliding body 18 having a spherical ball 30 on one end is formed, and a piston 20 having a cavity having a spherical bottom surface 44 and a groove 46 separated from the spherical bottom surface 44 with a prescribed distance, a profile forming part of an end part having an angled outer surface protruded outward to the outer surface 38 of the piston 20, and an inner surface 52 adjacent to the end part of the piston 20 is formed. The spherical ball 30 is inserted into the cavity and brought into contact with the bottom surface 44, and the inner surface 52 of the profile forming part of the piston 20 is pressed inward so as to make contact with the spherical ball 30, the angled outer surface is aligned to the outer surface 38 of a piston body 36 substantially in the longitudinally direction, and the whole outer surface of the piston 20 is hardened and finished into a prescribed size over the whole length.
HINRICHSEN MICHAEL H
SAVAGE HOWARD
SHERMAN DONALD H
WATTS KENNETH R
