Abstract: Known vacuum brake boosters are provided with a heavy sheet metal vacuum housing for transmitting reaction forces of the mechanical actuation to the booster carrier plate secured to a vehicle. According to the present invention the weight of the booster is remarkably reduced by providing draw bars for transmitting the reaction forces to the carrier plate inside the vacuum housing parallel to the push rod, penetrating the vacuum piston or movable wall and connecting both transverse end walls of the vacuum housing to the carrier plate. The draw bars are sealed at their point of penetration of the vacuum piston by small rolling membranes which are surrounded by tubular members fastened to the vacuum piston. A base plate assembly is provided including a base plate fastened to the transverse end wall of the vacuum housing adjacent the master cylinder, bolts fastened to one side of the base plate upon which the master cylinder is fastened and the draw bars are fastened to the other side of the base plate.