PENUMATIC BOOSTER

Japanese Patent JP3811869

B2

PROBLEM TO BE SOLVED: To provide a two radio-type pneumatic booster in which assemblage is improved by abolishing assembling work in a valve body. SOLUTION: A plunger 31 mounted in a valve body 22 is divided into a main body part 32 connected to an input shaft 34, and a unitized reaction receiving part 33 facing a reaction disc 45, the reaction receiving part 33 is provided with a shaft member 50 and a sleeve 51 fitted to it, and the sleeve 51 is energized forward by the specified set load by a compression spring 53 whose one end is seated on a spring shoe 52 fixed to the shaft member 50. While input is low, output reaction to be transmitted from an output shaft 46 through the reaction disc 45 is received by the sleeve 51 and the shaft member 50. When input larger than the set load is applied, the sleeve 51 is locked on a step part 30a of the valve body 32 by compression of the compression spring 53, the output reaction is received by only the shaft member 50, and the boosting ratio higher by one stage is obtained.