PostBus first used three-tone horns in 1924. At the time, no one could have predicted the hype the horn would cause.

If there were such a thing as an inventory of typical Swiss symbols, the Postbus three-tone horn would have to be part of it. Along with the colour yellow, it is PostBus’s most distinctive feature and signifies our brand. Because the car horns of the time were too quiet, Swiss Post had the horn developed in 1924. The triad still sounds today from three metal horns mounted on the underside of the Postbuses and equipped with an electric compressor. Postbus drivers use the horns when driving on mountain roads.