The invention is based on a vacuum motor as defined hereinafter. A vacuum motor of this kind has been set forth in (German Offenlegungsschrift No. 37 05 333 and European Patent Application 0173054 A2).
In the vacuum motor disclosed in German Offenlegungsschrift No. 37 05 333, a brake force can be built up at wheel brakes independently of the actuation of a control rod connected to the brake pedal, by means of an adjusting device disposed in a movable wall of the vacuum motor and acting upon a control device.
The adjusting device is actuated via a movably disposed line leading through a chamber of constant pressure The line communicates with a valve assembly that can be connected to a pressure source and a negative pressure source by means of control commands gene rated by a manual brake lever and transmitted to a control unit.
In the vacuum motor disclosed in European Patent application, a brake force can be built up independently of the actuation of the control rod connected to the brake pedal, by means of an elastic cylinder chamber that leads through a chamber of constant pressure and can be switched into a connection between a chamber of variable pressure and a valve asembly that is equipped with connections to a pressure source and to a negative pressure source. The valve assembly is controllable by commands of a control unit and is connected to a pressure source and a negative pressure source; the control unit processes sensor-measured values for the distance between two vehicles.
In the above set forth vacuum motors, only some of the possibilities for the use of the vacuum motor that is triggerable independently of the brake pedal have been disclosed.