Center-feed master cylinder with retainer for valve stem

Abstract

A master cylinder of the center feed type including a cylinder defining an axially extending pressure chamber and including a reservoir port proximate the front end of the cylinder for connection with a fluid reservoir; a piston slidably positioned in the cylinder and adapted for coaction with a piston rod extending into the rear end of the cylinder; a valve assembly in the pressure chamber including a valving member proximate the reservoir port and a valve stem secured to the valving member and extending axially rearwardly in the pressure chamber; and a retainer on the front end of the piston. The retainer includes a socket at its rear end for telescopic receipt of a reduced diameter nose portion on the front end of the piston and includes a plurality of rearwardly extending finger portions including head portions at their free, rear ends defining camming surfaces which coact with a camming surface defined by the head portion of the valve stem to cammingly separate the free ends of the finger portions in response to axial insertion of the head portion of the valve stem therebetween so as to snappingly connect the valve stem to the piston assembly in response to relative axial movement therebetween. The retainer is ultrasonically welded to the nose portion of the piston and coacts with the piston to define an annular outwardly opening seal groove at the interface of the retainer and the piston.