Patent ID: 6227628
Filing Date: 2001-05-08
Classification: B60T

Abstract:
A vehicle service brake, comprising:a vacuum brake booster;a dual brake master cylinder coupled with said vacuum brake booster;first and second brake circuits acted upon via pressurized fluid by way of the vacuum brake booster and the dual brake master cylinder;at least one switchable device operatively coupled with said first and second brake circuits to change a hydraulic pressure intensification by which, in an event of a failure of the vacuum brake booster, a brake fluid pressure is increased in each of the first and second brake circuits, wherein said at least one switchable device comprises step piston cylinder units connected fluidically downstream of the dual brake master cylinder and the first and second brake circuits, respectively and wherein the service brake further comprises an electrically triggerable valve operatively coupled with said step piston cylinder units to switch-over said units, wherein said electrically triggerable valve is a 3/2-way valve by which, in one switching position an input volume is connectable with an input-side ring volume of the step piston cylinder unit and, in another switching position, an output volume is connectable with the ring volume of the step piston cylinder unit.