Patent ID: 7343741

Claim:
A master cylinder ( 1 ) of an automobile, comprising a body ( 2 ) hollowed out to form a bore ( 3 ), at least one piston ( 4 , 5 ) sliding along a wall ( 6 ) formed by the bore of the body and defining a chamber ( 13 , 14 ), at least one hydraulic fluid reservoir ( 15 , 16 ) emerging in the bore, and at least one seal ( 21 , 22 ) for the chamber having a U-shaped section housed between the wall and the piston, characterized in that: the seal including a stiffening reinforcement ( 25 ) that extends circularly in a circular cylinder shape with an axis coaxial with an axis of movement of the piston, the reinforcement being formed of a wire having a series of identical crenellated portions, each connected to the remainder of the others, said portions each being formed of a first section ( 39 ) that extends in a first direction parallel to the axis of the piston, a second section ( 40 ) that extends from the first section and is carried by a first circumference of the cylinder and extending along a portion of the circumference of the cylinder, a third section ( 41 ) that extends from the second section in a second direction opposite to the first direction and a fourth section ( 42 ) that extends from the third section and is concentric with the second section and is carried by a second circumference of the cylinder, said seal having an outer lip ( 27 ) and an inner lip ( 28 ), the outer lip and the inner lip being connected by an intermediate section ( 29 ), the outer lip being placed at a first location away from the piston and the inner lip being placed at a second location close to the piston, the inner lip including the reinforcement, said piston ( 4 ) having a peripheral rebate ( 31 ) hollowed on it's circumference, against which the top of the inner lip of the seal ( 21 ) bears to form a stop for the piston inside the body ( 2 ).