Patent ID: 8261546

Claim:
A vehicle hydraulic master brake cylinder assembly, comprising: a master cylinder housing having a generally cylindrical bore; primary and secondary pistons are reciprocally disposed in the bore and defining in conjunction therewith primary and secondary brake fluid pressure chambers; primary and secondary reservoir pots connecting with primary and secondary conduits configured to convey hydraulic fluid between a fluid reservoir and the primary and secondary chambers respectively; and a valve member movable between an open position in which the primary pot is in fluid communication with the primary conduit and a closed position in which the primary pot is isolated from fluid communication with the primary conduit, wherein the secondary piston is moveable between a first piston position and a second piston position, and wherein movement of the secondary piston from the first piston position to the second piston position causes said secondary piston to directly contact the valve member so as to move the valve member from the closed position to the open position.