US Patent 7698988 Brake booster for a hand brake

The invention relates to a brake booster intended to transmit handbrake commands. This booster essentially comprises a plunger (3) able to move axially under the command of the control rod (1). An enclosure (2) contains a working chamber (21) and a vacuum chamber (20) which are separated by a wall (22) able to move axially under the effect of the plunger (3) and/or of a difference in pressure between the vacuum chamber and the working chamber. A three-way valve (4) controlled by the plunger (3) allows the working chamber (21) to be connected either to the vacuum chamber or to atmospheric air. Finally, a bearing piece (17) controlled by the moving wall (22) allows the control rod (1) to be driven along.