Before the introduction of the electrically operated braking system in the motor car there was some concern that one would lose the direct controlling influence. As far as trucks, with their compressed-air brakes are concerned, this has been the case for quite some time now. The air-pressure developed by engine power can produce very high pressure through piston- or membrane cylinders. After decades a safety standard has been achieved, whereby trucks no longer have a significantly higher brake damage than do motor cars. Why then, is the compressed-air brake only found in mid-range- to heavy trucks? The reason is, that up to twenty times more mass has to be braked than is the case with a motor car. This cannot be achieved by increasing the force on the brake pedal. The solution is that the total operating force must be produced by the braking system, whereby, the compressed-air to the wheel-brakes is very sensitively regulated by the pedal-force from the driver. However, such an expensive and space consuming system is only possible in the truck- and bus area.