Patent ID: 6959637
Filing Date: 2005-11-01
Classification: B60T,F15B

Abstract:
1. A brake booster having a wall that moves within a cavity of a housing in response to a pressure differential to produce an output force as a function of an input force communicated from an input member to a control valve arrangement, said output force being transmitted through a hub for said wall to an output member to effect a desired brake application, said brake booster being characterized in that said hub includes a first cylindrical member having a first stepped bore that extends between a first end and a second end for receiving a second cylindrical member with a second stepped bore therein that extends between a first end to a second end, said first stepped bore having first and second longitudinal slots that extend from said first end toward said second end, said second cylindrical member having third and fourth longitudinal slots there through that extend from said second stepped bore and are located in a same plane between said first end and said second end thereof, said second cylindrical member having first and second lateral openings with respect to the axis of said second cylindrical member and that are normal to said third and fourth longitudinal slots; a plunger of said control valve arrangement having a shaft that is located in said second stepped bore with a first end positioned adjacent said second end of said second cylindrical member, said shaft having a fifth longitudinal slot there through and first and second lateral oval openings that extend from and are normal to said fifth longitudinal slot, a gear having an axle aligned with said first and second lateral openings in said second cylindrical member and with said first and second oval openings in said plunger, a pin that passes through said first and second oval openings and is retained in said first and second lateral openings such that teeth on a peripheral surface of said gear extend through said third and fourth longitudinal slots and into said first and second longitudinal slots, a first rack located in said first longitudinal slot and engaging a first plurality of said teeth on said gear and a second rack located in said second longitudinal slot and engaging a second plurality of said teeth on said gear, said second rack being fixed to said housing while a clip member attached to said first cylindrical member provides a stop to prevent said first rack from moving past said first end of said first cylindrical member, said first cylindrical member and said wall moving together during a brake application such that on said first rack engaging said clip a rotative torque is imparted to said first plurality of teeth of said gear that causes said gear to rotate about said pin and move said second plurality of teeth with respect to said second rack such that said second cylindrical member separates from said first cylindrical member and as a result the travel of said input member is about one-half of the travel of said output member.