Servo boosters for vehicle braking systems

Claim 1

A servo booster for a vehicle braking system comprising a booster housing, output and input members at the front and rear respectively of the booster, front and rear housing walls of said booster housing, a movable wall dividing the interior of said booster housing into front and rear chambers, said movable wall comprising a diaphragm support plate and a flexible diaphragm which seals said movable wall at its radially outer periphery to said booster housing, a valve body, an integral connection connecting said diaphragm support plate to said valve body, force transmitting means comprising a tube which is substantially co-axial with the movable wall and extends forwardly from said rear housing wall in fluid tight relationship therewith, said tube extending to said front housing wall and being stationary with respect to the vehicle in use and arranged substantially to relieve said booster housing of braking reaction forces, seal means fixedly sealing said movable wall at its radially inner extremity to the radially outer surface of said tube, said tube having at least one aperture therein, said integral connection connecting said diaphragm support plate to said valve housing comprising an arm extending through said aperture, a valve member located in said valve body, said valve body being provided with a valve chamber adjacent to said valve member, and a fluid conduit connecting said valve chamber and said rear chamber, said fluid conduit comprising intercommunicating first, second and third passages in said valve body, integral connection and diaphragm support plate, respectively, said first passage of said fluid conduit opening to said valve chamber, and said third passage of said fluid conduit opening to said rear chamber radially outwards of said seal means.