Dual reaction ratio power booster

摘要

A power booster is operable at relatively low apply rates and at relatively high apply rates and includes an input assembly that has a movable input rod and a primary reaction piston having a first reaction area. An output support body is responsive to movement of the input rod, with a resilient reaction disc engaging the output support body. A secondary reaction body has a second reaction area and is engageable with the reaction disc and transfers loads between the reaction disc and the input assembly at relatively low apply rates. The amount of the load transferred is a function of both the first reaction area and the second reaction area at the relatively low apply rates resulting in a first reaction ratio. The primary reaction piston is engageable with the reaction disc and transfers loads between the output support body and the input assembly during relatively high apply rates. The amount of the load transferred is solely a function of the first reaction area at the relatively high apply rates resulting in a second reaction ratio that is smaller in magnitude than the first reaction ratio.