NEGATIVE PRESSURE TYPE BOOSTER

摘要

PROBLEM TO BE SOLVED: To provide a negative pressure type booster having a simple and compact constitution and stabilizing a threshold value when emergency brake characteristic is obtained.

SOLUTION: A retaining means for retaining a slide valve 60 to a front predetermined position is provided with an engagement member 64 linearly movably installed to a power piston 30 in a radial direction; and a garter spring 65 for radially inwardly urging the engagement member 64. A hook 64a engageable/disengageable with a hook 60b provided on the slide valve 60 and constituting the retaining means with the garter spring 65 or the like is provided on the engagement member 64. When a plunger 41 is advanced more largely than a predetermined value relative to the power piston 30, a receiving slant surface 64c of the engagement member 64 is radially outwardly is pressed/moved by a pressing/moving slant surface 41d of the plunger 41 and the hook 64a of the engagement member 64 is detached from the hook 60b of the slide valve 60.

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