Servo-boosters for vehicle brake systems

Claim 1

A differential-pressure operated servo booster of the type having a load actuating member which is displaceable by the application of differential fluid pressure across an annular elastic diaphragm, comprising a housing, a diaphragm dividing the housing into two chambers, valve means located coaxially of the booster axis for controlling the relative pressure in said two chambers, a plurality of rigid, individual, radially extending fingers which define a radially slotted annular deflecting plate, an annular skirt member located coaxially within the housing and having an axially extending portion and a radially inwardly projecting portion, the diaphragm having a first portion which extends generally radially outwardly of the booster axis and a second, axially extending portion which is located radially outwardly of the deflecting plate and which is supported by said axially extending portion of the annular skirt member and the radially inwardly extending portion of the annular skirt member including a first radially inwardly extending limb which is engaged by that side of each of the fingers which faces towards said valve and at least one second radially inwardly extending limb which engages the other side of at least some of the fingers and wherein said second limb is axially spaced from said first limb and extends radially inwardly from the axially extending portion of said skirt.