Patent ID: 6802240
Filing Date: 2004-10-12
Classification: B60T

Abstract:
A booster comprising a valve body slidably disposed within a shell, a valve plunger slidably fitted over the valve body and mechanically coupled to an input shaft, an output shaft having a closed-end cylindrical base which opens rearwardly and is slidably mounted on the valve body, an annular stop fixed to a predetermined position in an axial direction in the base, a reaction disc disposed between a rear end face of the annular stop in the base of the output shaft and a front end face of the valve plunger, an abutment member movably disposed in the base at a position closer to the front of the base than the stop and having a rear projection slidably fitted in the stop and an urging member disposed in the base at a position closer to the front of the base than the stop for abutting a rear end face of the rear projection to a front end face of the reaction disc by urging the abutment member towards the rear, the urging means being compressed after actuation of the booster and the rear projection of the abutment member moves toward the front of the base by a corresponding amount with respect to the stop to allow the reaction disc to bulge into the stop and increase the servo ratio, the base of the output shaft being formed by a holder which is separate from an axially extending rod member, the stop being separate from the holder, the holder being in the form of a bottomed cylinder having a bottom which is secured to the rod member, the stop being secured inside the cylinder, the abutment member and the urging member being disposed between the stop and the bottom and the urging member comprising either a plurality of concentrically disposed coiled springs or a single coiled wave spring.