The design of the Dual Rate Vacuum Brake Booster provides a progressive pedal feeling in an emergency. As in the case of conventional boosters, the input/output ratio depends on the relationship between the loaded surface areas of the ratio disc and the output rod. The main difference from the standard booster is that the effective area of the ratio disc in the Dual-Rate case is divided into two parts. This affects the required area change during actuation.

Response times are not affected by the Dual-Rate function. The remarkable feature of this Dual-Rate is that the whole function takes up no more space than the normal ratio disc of a tandem booster, which means that an interchange can be made in both directions.

Component PDF: 

11 tech sheet FINAL Dual Rate _DR__Englishjw82311.pdf