Pneumatic brake booster with changing boost ratio

摘要

The servomotor has a sealed partition (6) provided with a pneumatic piston body and movable between front and rear chambers (1, 3). An intake device intaking high pressure fluid in the chamber (3) via an opening an intake valve (4) during driving of a control rod (9) at the moment of braking. Another intake device widely opens a high pressure fluid intake valve in the rear chamber and has an extrusion producing unit formed of a circular rim shaped pad that produces an extrusion of a reaction disk (23) and is oriented from a side of the control rod.