PNEUMATIC BRAKE BOOSTER

摘要

The invention relates to a pneumatic brake booster which is intended, in particular, for a motor vehicle. The inventive device comprises (i) a piston (22) which is mounted between a brake pedal-actuated control rod (24) and a push rod (34) which actuates a piston of the brake master cylinder and (ii) means of increasing brake assistance during emergency braking, comprising a cylindrical sleeve (46) which is mounted axially to slide in an impervious manner inside the aforementioned piston (22). Said sleeve (46) is held in the rest position by blocking means (58) and is released in order to push back the check valve (56) of a three-way valve and to increase the servomotor atmospheric air supply when the control rod (24) is moved at a speed greater than a pre-determined value.