Abstract: A vacuum servo brake has an input member by which a valve arrangement may be acted upon at an input force to connect a working chamber selectively to the outside or to a vacuum chamber (separated from the working chamber by a piston which may be brought into operative connection with a main cylinder via an output member to generate a braking pressure). Provided on the piston is an elastomeric reaction member through which a reaction force may be applied to the input member. The output member has a stop which, with a predetermined input force, abuts against the working piston to alter an amplification ratio of the brake. Arranged adjacent to the reaction member is at least one volume take-up means into which part of the reaction member may be displaced in the event of the vacuum servo brake being actuated. Furthermore, the stop is preferably of resilient construction.

Abstract: A vacuum servo brake has an input member by which a valve arrangement may be acted upon at an input force to connect a working chamber selectively to the outside or to a vacuum chamber (separated from the working chamber by a piston which may be brought into operative connection with a main cylinder via an output member to generate a braking pressure). Provided on the piston is an elastomeric reaction member through which a reaction force may be applied to the input member. The output member has a stop which, with a predetermined input force, abuts against the working piston to alter an amplification ratio of the brake. Arranged adjacent to the reaction member is at least one volume take-up means into which part of the reaction member may be displaced in the event of the vacuum servo brake being actuated. Furthermore, the stop is preferably of resilient construction.