BRAKE BOOSTER WITH DUAL RATE BRAKE ASSIST

摘要

A pneumatic brake booster (12) with a decompression arrangement (80) wherein an output push rod (24) has a head (26) with a plurality of axial openings (72) that extend into a stem (66) and create a plurality of arcuate grooves (74). The openings (72) receive a plurality of radial projections (64) that extend from a piston (45) retained in a sleeve (100) held in a movable partition (18). A spring (70) acts on the radial projections (64) and urges the piston (45) into engagement with a reaction disc (28) through which an actuation force is supplied a master cylinder, A predetermined reaction force from the master cylinder acts on piston (45) and overcomes the spring (70) to allow the reaction disc (28) to expand and thereby modify the reaction force. The arcuate grooves (74) in the stem (66) allow for a maximum diameter for spring (70) with a minimum diameter for stem (66) that corresponds to a diameter of the piston (45) in order to creates a desired braking in response to an emergency brake application.