Patent ID: 6318242
Filing Date: 2001-11-20
Classification: B23P,F04B,Y10T

Abstract:
A method of making a hydraulic piston for a rotating hydraulic pump or motor, comprising,cold forming a blank metal piston body to create a hollow cylindrical body with a closed end, an open end, and a center bore of uniform cross section,placing a metal insert slug into the center bore which has a complimentary cross-section to that of the center bore and having an interior end adjacent the closed end of the center bore and an outer end spaced inwardly from the open end of the center bore to leave open an outer end portion of the center bore, with the insert slug being of a material less dense than that of the material of the piston body,cold rolling the open end of the piston body to deform the piston body around the outer end portion of the center bore to decrease the diameter of the outer end portion of the center bore and to partially encompass the outer end of the insert slug,cold forming a partial spherical-shaped socket in the outer end portion of the center bore,and placing a spherical shaped slipper member in the socket.