Patent ID: 8539766

Claim:
A master cylinder comprising: a cylinder bore; a first piston positioned within the cylinder bore; a second piston positioned within the bore and located forwardly of the first piston; a first pressure chamber within the cylinder bore and defined in part by a rear portion of the second piston and a forward portion of the first piston; a first pressure chamber seal extending radially outwardly from the rear portion of the second piston; a first reservoir inlet configured to provide fluid communication between a reservoir and the cylinder bore at a location forwardly of the first pressure chamber seal; and a first groove extending axially along the cylinder bore and positioned such that (i) when the second piston is in a released position, the first groove is located directly outwardly of the first pressure chamber seal and the reservoir is in fluid communication with the first pressure chamber through the first groove, and (ii) when the second piston is in an activated position, the first pressure chamber seal isolates the reservoir from the first pressure chamber at a location forwardly of the first groove.