Electro-hydraulic brake booster with housing made of moulded plastic in two parts

The servo-brake (100) has a supporting sleeve (5) between a return spring (41) of an actuating piston (4) and the piston. The sleeve includes a support (52) for a spring (53) against a front face of a rear end (71) of a push rod (7) for moving the push rod against the bottom of a front cavity of a support piston. The support piston is connected to the actuating piston by driving the support piston in an actuating direction (FAV) of the servo-brake, where the support piston is free to move in an initial phase of action of a plunger by a control rod (102) without connection to the return spring.