| 摘要 |
PROBLEM TO BE SOLVED: To provide such a feeling that a brake depressing force is smaller and more effective at the time of abrupt braking by reducing a servo-ratio by a spring means 1 in a range where a small braking force is required, increasing the servo-ratio when a brake reaction force is increased, and reducing an acting force applied on a reaction piston more than that applied in a normal brake application using an orifice. SOLUTION: In a braking force boosting device having a spring means 31 between a reaction disk 7 and a valve plunger 11, a reaction piston 25 is installed in the valve plunger 11, an air reaction force chamber 26 is formed on the front side of the reaction piston, and the air reaction force chamber is communicated with a pressure variation chamber 7 through an orifice. Thus a pressure in the pressure variation chamber is applied to the front side of the reaction force piston, and a pressure in a constant pressure chamber is applied to the rear side of it. |
