Patent ID: 6550246
Filing Date: 2003-04-22
Classification: F15B

Abstract:
A master cylinder comprising:a casing defining a bore, an annular groove surrounding the bore between forward and rearward ends of the bore and defining a forward bore portion forwardly of the annular groove and a rearward bore portion rearwardly of the annular groove, and a port connecting the annular groove with a reservoir for containing hydraulic fluid; a seal positioned in the annular groove; a piston mounted for stroking movement between extended and retracted positions and having a forward end positioned forwardly of the annular groove in a rearward section of the forward bore portion with the piston in its retracted position whereby, in its retracted position, a rear end of the piston is guided in the rearward bore portion and the forward end of the piston is guided in the rearward section of the forward bore portion; axial groove means at the interface between the forward end of the piston and the rearward section of the forward bore portion establishing communication, with the piston in its retracted position, between the bore forwardly of the piston and the annular groove; and port means in the piston communicating at one thereof with the bore forwardly of the piston and opening at another end thereof exteriorly of the piston at a location, with the piston in its retracted position, rearwardly of the seal.