| 摘要 |
PURPOSE: To quickly increase the output of a brake booster 1 by instantly responding to an abrupt treading operation of a brake pedal. CONSTITUTION: A valve body 3 is comprised of a first vacuum valve seat 17, and a cylindrical member 21 slidably provided in the valve body 3 is comprised of a second vacuum valve seat 18. A lever member 41 is provided between the cylindrical member 21 and a valve plunger 14, and when the valve plunger 14 strokes prescribed strokes or more to the valve body 3, the lever member 41 is turned so that the cylindrical member 21 retreats to the rear side relative to the valve body 3. When the brake pedal is abruptly stepped down, the lever member 41 is turned so that an engagement projection part 41f is engaged with an engagement recess part 44 of the valve body 3 to retain the cylindrical member 321 in a position retreated to the rear side relative to the valve body 3. This constitution can open a breather valve more widely than the ordinary operation so as to quickly provide a large output.
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