Master cylinder with piston retainer

Abstract

A master cylinder comprising a cylinder body having a bore, a plunger in the bore, a bearing secured to the rear end of the cylinder body and slidably supporting the plunger, a sleeve fitted in the cylinder bore adjacent to the bearing and receiving the plunger therein, and stopper means between the sleeve and plunger for defining a retreat limit of the plunger, wherein the cylinder body is connected to a booster shell with a sealing member therebetween, and the rear end of the plunger protrudes into the booster shell for connection to an output rod of the booster, the sealing member having a lip placed in close contact with the outer peripheral surface of the plunger. An annular set screw is threadedly mounted to the rear opening of the cylinder bore to fix the sleeve while surrounding the plunger, so that the lip of the sealing member is received in a tool-engaging recess provided on the set screw. Alternatively, the plunger comprises a front plunger and a rear plunger. In this case, a rear return spring for biasing the rear plunger in a retreating direction is disposed in a rear hydraulic chamber between the front and rear chambers, wherein a forwardly projecting guide shaft is mounted on the rear plunger, the rear return spring being compressed between the rear plunger and a spring retainer tube slidable on the guide shaft. Stopper means is provided between the spring retainer tube and the inner peripheral wall of the rear hydraulic chamber.