Patent ID: 8590304

Claim:
A master cylinder of a hydraulic braking circuit, the master cylinder comprising: a body ( 4 ) having a rear surface ( 32 ); a piston ( 2 ) axially slidable in the body ( 4 ); an annular lip seal ( 51 ) engaged with the piston ( 2 ) the lip seal ( 51 ) comprising: an internal, dynamic sealing lip ( 14 ) surrounding the piston ( 2 ); a rear face ( 30 ) comprising an annular, radially inner ring ( 52 ), a plurality of radially extending grooves ( 34 ), and a plurality of raised blocks located radially outwardly of the inner ring ( 52 ), the radially extending grooves ( 34 ) extending between the raised blocks; and a curved surface ( 36 ) connecting the sealing lip ( 14 ) to the inner ring ( 52 ); wherein the plurality of raised blocks are configured to press against the rear surface ( 32 ) of the body ( 4 ); wherein the inner ring ( 52 ) and the grooves ( 34 ) form a continuous, planar surface along the rear face ( 30 ), the continuous, planar surface being recessed from the raised blocks.