| 摘要 |
PROBLEM TO BE SOLVED: To provide a negative pressure type booster capable of suppressing contact sound due to contact of a valve seat member, an integrally retreating key member and a flange face of a plunger by properly relaxing a retreating speed of the valve seat member. SOLUTION: A spring 62 giving prescribed set weight is provided on the plunger 37, and in the case that an amount of advancement to a power piston 22 of the plunger 37 is a prescribed value or larger, the valve seat member retreats a prescribed amount toward a movable part 41 against urging force of the spring 62. |
