Safety, Cleanliness and Economy (German: Sicherheit, Sauberkeit and Sparsamkeit = 3 S), these three concepts run like a red thread through the history of Bosch automobile technology. When the development aim that had been pursued for decades was finally given the name "3 S Programme" in 1974, one of its early contributions had already disappeared from the traffic scene: the Bosch trafficator.
The trial period of the motor vehicle, which can be dated from 1886 to around 1910, demonstrated that the "horseless carriage" was relevant as a means of locomotion. "Only then," as Peter Kirchberg puts it in an investigation into the motorization of road traffic in Germany, "[...] did it really offer new possibilities as a means of transport, only then did it offer tried-and-proven variants to supplement the existing transport system." "Between the two World Wars, the motorization of traffic in Germany was accomplished in two great periods of growth, separated by the World Economic Crisis. The number of motor vehicles on the road grew considerably in the 1920s and 1930s [...]."

In order to combat the increasing chaos on the roads, rules and regulations were needed. Signals were becoming more and more important in this context. Paragraph 26 of the Motorized Traffic Regulations thus required that: "The driver must indicate to other persons, well in advance, his intention to stop by holding his arm up vertically, his intention to turn around and to leave the direction in which he had previously been driving by holding out his arm horizontally in the direction he wishes to change to; a mechanical device may also be used to give such indications."

So in 1927/28, when the development department at Bosch turned its attention to the problem, the idea of a mechanical direction indicator, as provided for even in this early legislation, was by no means new. The early 1920s saw metal signal arms with red "Bakelite eyes", which could be activated by a mechanical lever switch via cables running along the floor of the vehicle. Other manufacturers, particularly Carl Zeiss of Jena, already had devices incorporating an arrow inside an internally illuminated capsule-shaped housing which could be turned in the desired direction of movement by means of two electromagnets. At Bosch, however, it was assumed right from the start that giving such signals should cause a noticeable change in the actual contours of the vehicle.

The Bosch trafficator basically consists of an electromagnet which, when the trafficators switch is activated, swings the trafficator arm out of its housing. At the same time, the trafficator arm is illuminated by a bulb in order to make it clearly visible in the dark. Shutter-like corrugations on the back of the trafficator arm effectively protect the driver from being dazzled by the trafficator light. After all the aim, even then, was to make a contribution towards traffic safety.

From 1956 onwards, motor-vehicle registration legislation prescribed flashing indicators as part of the essential basic equipment for all new vehicles. Owners of older cars were given until 1961 to re-equip their vehicles accordingly. The Bosch trafficator disappeared from the streets. But this was no problem: after all, the new Bosch flashers had long been available on the market.