Patent ID: 7430864

Claim:
A master cylinder comprising a cylinder body having an inner wall defining a cylinder bore, a primary piston and a secondary piston both slidably mounted in said cylinder bore, and a stopper plate disposed in said cylinder bore behind said secondary piston, said inner wall having sliding surfaces along which said primary and secondary pistons slide respectively, said sliding surfaces having a first diameter, said inner wall further having a groove formed at a longitudinally intermediate portion of said inner wall, said groove having a second diameter larger than said first diameter, said stopper plate having a pair of diametrically opposed flanges having outer edges defining a circle having a third diameter larger than said first diameter and smaller than said second diameter, said flanges being received in said groove so as to be engageable with said secondary piston and a shoulder formed on said inner wall at a rear end of said groove, said stopper plate having a dimension perpendicular to the direction in which said flanges extend and smaller than said first diameter.