Patent ID: 6837048

Claim:
A master cylinder havign a body with a longitudinal axis (X) pierced with a bore along the axis (X), and at least one piston ( 10 ) mounted to sealingly slide within said bore, said piston ( 10 ) comprising a piston head ( 32 ) with a piston shank ( 34 ) connected to the piston head ( 32 ) via a shoulder ( 36 ), said piston shank ( 34 ) being guided by a guide ring ( 38 ) mounted fixedly in said body, said piston head ( 32 ) coming at rest and bearing against a thrust ring ( 42 ) via the shoulder ( 36 ), said piston ( 10 ) having a body that delimits a work chamber ( 16 ) from which pressurized brake fluid is communicated to brakes during a brake application and a supply chamber ( 14 ) that is placed in communication at rest with said work chamber by a valve device ( 18 ) arranged in the body of said piston ( 10 ), a supply duct ( 24 ) having a first longitudinal end ( 37 ) sealingly connected to a brake fluid reservoir and a second longitudinal end ( 39 ) located adjacent said thrust ring ( 42 ) and allowing the supply chamber ( 14 ) to be supplied with brake fluid via a resupply duct ( 44 ) and hydraulic damping means ( 48 ) for damping the return of said piston head to bear against the thrust ring ( 42 ), characterized in that the hydraulic damping means ( 48 , 51 , 56 , 71 ) comprise a means ( 41 ) for shutting off said second longitudinal end of the supply duct ( 24 ) and at least one exhaust duct ( 50 , 54 , 58 , 60 , 72 ) that restricts the flow rate of the brake fluid from the supply chamber ( 14 ) to the supply duct ( 24 ).