Vacuum booster

摘要

An object of this invention is to minimize invalid stroke in operation while effectively utilizing the advantages available for the type in which a valve body of a vacuum valve (500) and a body of an atmospheric air valve (700) are separately formed. To achieve the object, there is provided a cylindrical inner member (800) air-tightly and slidably fitted in the internal bore of a hub portion (52) of a servo piston (50). The inner member (800) is biased backwardly by a spring (850). The inner member (800) has at its front end a valve body (510) of the vacuum valve (500). The rear end of the inner member (800) is caused to be abutted with the atmospheric air valve body (710) side of the atmospheric air valve (700) under the effect of force of the spring (850). <IMAGE>