Abstract: The actuator comprises a piston (34) which has a stepped portion (36) formed with an annular groove (38) at its end projecting out of a cylinder (16). An annular protective sheet (50) is slipped on the stepped portion (36) and it comprises at its radially inner edge (52) inwardly projecting, resilient tongues (54) which are arrested in the annular groove (38). An annular elastic sleeve (46) is arranged behind the protective sheet (50), thereby being protected against heat, and provides sealing as against the piston (34), on the one hand, and the cylinder (16), on the other hand.

Abstract: This invention relates to a plurality of two-arm levers employed in brake boosters for summing the control force applied by the brake pedal and the booster force applied by the brake booster and for transmitting the resultant sum of forces to the hydraulic system actuation device. The two-arm levers are interconnected in the range of their balancing point or between their balancing point and their inner radial end by an elastic connection. This arrangement of two-arm levers provides one piece that improves the assembly of the two-arm levers in a brake booster.