One of the most important components in the car, the tachometer, is celebrating its 110th birthday this year. In October 1902, engineer Otto Schulze registered a patent for an eddy current tachometer in Berlin – and thus revolutionized the world of speed measurement. Today, every road vehicle must be equipped with a tachometer. And it can do much more than just indicate the current vehicle speed.
The tachometer’s success story did not begin until a few years after the invention of the motor car. It was only as engine power increased that the reliable measurement of vehicle speed became essential. “Because although humans can perceive positive or negative acceleration with their equilibrium organ, they are not so perceptive at constant speeds,” explains Eelco Spoelder, head of the Instrumentation & Driver HMI business unit at the international automotive supplier Continental. The triumph of the tachometer began – initially as an expensive extra. From the mid-1930s, the first instrument clusters were built, with displays for speed, fuel supply and indicator lights.
The original tachometer worked on a purely mechanical principle and experienced a first technological leap with the introduction of the electric tachometer in the mid-1950s. With this principle, instead of a shaft transferring the wheel revolutions, a dynamo transformed the wheel or transmission speed into an electric signal. Today, the tachometer pointer is usually moved by a stepper motor. Only surprising at first glance: the shape of the instruments has hardly changed in 110 years. Despite fashionable versions with digital LCD displays or cylinders, the classic round tachometer dominates many cockpits. This is mainly for ergonomic reasons, since round instruments are intuitive to read and thus do not distract drivers from their driving. Incidentally, modern instrument clusters can display lots of additional important information – such as fuel consumption or average speed.
A look into the future: the trend towards more infotainment – music systems, cellphones or satnav equipment – demands new strategies from manufacturers. Because the more infotainment there is available to the driver in the center console, the greater the risk of distraction will be. “These days, it is almost impossible to strictly separate drive-related information in the instrument cluster from infotainment in the center console,” Spoelder says. For this reason, Continental is banking on a variable concept where drivers can decide which information they require, depending on the situation. These new displays are designed with a mixture of analog instruments, such as tachometers or rev counters, and screens for further information.
And there is another trend: head-up displays are on the rise, and supply drivers with important information. With these displays, data such as speed or navigation instructions are projected onto the windshield and thus directly into the driver’s field of vision – for additional safety and clarity.
Whatever direction the display of drive-relevant data may take, even complex contents will be shown in a more straightforward and clear manner in future. Nevertheless, the tachometer will remain a very important element in the cockpit.