Abstract: A pneumatic booster has a valve member arranged to operate stably even under a large differential pressure. The inside of a housing is divided into a constant-pressure chamber and a variable-pressure chamber by a diaphragm. A plunger and a valve member are disposed in a valve body supported by the diaphragm such that the plunger and the valve member are slidable relative to each other. The valve member is formed from a rigid reinforcing member and an elastic member bonded to the reinforcing member. The plunger is movable in association with an input shaft. The movement of the plunger is transmitted to the valve member through a valve spring, causing the valve member to separate from a seat portion provided on the plunger.

Abstract: The present invention provides a booster of the gaseous pressure type.

Abstract: A pneumatic booster comprises a piston dividing a housing into front and rear chambers, the front chamber being is constant communication with a vacuum source, the rear chamber being selectively supplied with an atmospheric pressure source or a compressed air source, wherein a valve body of the piston includes a bore having a retainer mounted within, and an input rod movable within the retainer and having a compressed air passage extending therein, the bore of the valve body also having a first rear control valve and a second front control valve, such that movement of the input rod opens the first rear control valve to allow atmospheric air into the booster chamber and a further movement of the input rod opens the second front control valve to allow compressed air into the booster chamber, resulting in an increased output force of the booster.