| 摘要 |
PROBLEM TO BE SOLVED: To provide a negative type booster contriving reduction of working sound in emergency braking operation. SOLUTION: In the case that an amount of relative movement in the forward direction is a prescribed value or larger to a power piston 22 of a plunger 37, engagement of a holding member 48 and a valve seat member 40 is released to retreat the valve seat member 40, even when a key member 32 is moved rearward, elastic members 32a, 32b are disposed in the inside of the valve seat member 40 between a frontward end face 35a of a second flange part 35 of the plunger 37 and a rearward face 32c of the key member 32, and working sound is reduced by both contact between the frontward end face 35a of the second flange part 35 and the rearward face 32c of the key member 32 due to deformation of the elastic members 32a, 32b. |
