Patent ID: 7240602

Claim:
A pneumatic brake booster ( 14 ) comprising: an axially movable control member ( 20 ) for controlling this booster and receiving a control force applied by a user; a pneumatic enclosure ( 16 ) having a rear chamber (CA) separated from a front chamber (CB) by a pneumatic piston ( 22 ); and means for forming pneumatic valves comprising: first (VE 1 ) and second (VE 2 ) complementary balancing valve elements for placing the rear chamber (CA) in communication with the front chamber (CB), and first (VA 1 ) and second (VA 2 ) complementary intake valve elements for placing the rear chamber (CA) in communication with a pneumatic pressure source, characterized in that: said means for forming pneumatic valves comprise an axially floating tubular support ( 44 ) provided with an intake part ( 44 A) and a balancing part ( 44 B) that move axially with respect to one another to adjust the length of said tubular support ( 44 ); the first (VE 1 ) and second (VE 2 ) balancing valve elements are borne respectively by balancing part ( 44 B) of said tubular support ( 44 ) and the pneumatic piston ( 22 ); the first (VA 1 ) and second (VA 2 ) intake valve elements being borne respectively by the control member ( 20 ) and the intake part ( 44 A) of said tubular support ( 44 ); and the balancing part ( 44 B) and intake part ( 44 A) of the tubular support ( 44 ) are connected to one another by means ( 52 ) for adjusting the axial separation thereof as a function of the power of the force applied to the control member ( 20 ).