Patent ID: 7634960

Claim:
A pneumatic brake booster for motor vehicles comprising: a booster housing, subdivided into at least one working chamber and at least one vacuum chamber by at least one axially movable wall to which a pneumatic differential pressure can be applied, a control valve controlling the differential pressure and being arranged in a control housing in order to connect the working chamber to the vacuum chamber or to the atmosphere, said valve being composed of two concentrically arranged sealing seats as well as an elastically deformable valve member, an operable input member, connected to a valve piston whose movement in an axial direction is limited by a transverse member that can be introduced in a radial direction into the control housing, an elastic reaction element, an output member applying a boosting force to a master cylinder, and ventilating and bleeding ducts, which are provided in the control housing and allow evacuating or ventilating the working chamber, wherein two bleeding ducts and two ventilating ducts are provided in the control housing, which extend over a total available circular cross-section of the control housing, and the ventilating ducts are interrupted in each case by two webs in order to accommodate the transverse member.