Speedometer: Mercedes-Benz Museum Inside No. 24/2021
- Speed indication as monitoring instrument
- Formerly an analogue dial, now part of the digital cockpit
- “33 Extras”: Exhibits of motoring culture at the Mercedes-Benz Museum
Stuttgart. 160 vehicles and a total of 1,500 exhibits are presented in the varied permanent exhibition of the Mercedes-Benz Museum. The “33 Extras” are a particular highlight: they can bring the history of personal mobility and motoring culture to life using details that are often surprising. The Mercedes-Benz Museum Inside newsletter series draws attention to the “33 Extras” and focuses on their background stories. Today’s edition is all about the speedometer.
Moderate start: 16 km/h – that was the top speed of the world’s first car. Not exactly fast as lightning, even in 1886 – considering steam locomotives had already smashed the 100 km/h barrier decades before. However, Carl Benz’s Patent Motor Car still reached twice the speed of pedestrians, but the innovative vehicle nevertheless lacked a speedometer. There wasn’t much of a point. There were no statutory speed limits.
Sought-after extra: However, with the increasing popularity of the car, speedometers became available as optional equipment as fast cars were considered good cars. And it goes without saying that you’d want to know how good your own vehicle was. The speedometer on display as part of the Mercedes-Benz Museum’s “33 Extras” in Legend Room 3 “Times of Change – Diesel and Turbocharger” represents such optional equipment. Its gauge went up to 100 km/h.
Limit: Speed limits were not introduced until vehicles became increasingly faster. Initially these limits were adapted to the traffic situation before the age of the car. As of 1909, 15 km/h was the top speed in built-up areas throughout the German Reich, which corresponds to the speed of a trotting horse. From that point onwards, cars without speedometers were a thing of the past. Not only did vehicle drivers have to keep an eye on the road and traffic situation, they also had to check their speed.
Indication: Speedometers measure speed and indicate it as a numerical value. The German term for speedometer, “Tachometer”, is derived from the ancient Greek terms “tachýs”, denoting “fast”, and “métron”, meaning “dimension”. For decades, an analogue dial with a needle pointed to the corresponding dot or line on the scale. Digital speedometers have been around since the 1990s. They are more flexible and are capable of changing the way they show data. Regardless of the technology: speedometers always indicate a slightly higher speed than the actual speed the vehicle is travelling at – giving us all a bit of leeway on everyday journeys. This was prescribed by law to compensate for inaccuracies in speed measurements.
Integration: The speedometer had initially not been positioned in the driver’s field of vision. It had only been placed there since the 1950s. The scale highlights important values, such as the top speed in built-up areas, 50 km/h in Germany. The dial is the dominant design, but there were also other variants: for instance, the horizontal indicator in Mercedes-Benz W 180/W 128 model series “Ponton” Saloons (1954 to 1959) or the vertical indicator, lovingly called “thermometer” by aficionados, in W 111/W 112 model series “Tailfin” Saloons (1959 to 1965).
Monitoring: If you don’t keep an eye on the speedometer and exceed the speed limit, you may become familiar with an unpopular device which has been in use in Germany since 1959: colloquially known as the “speed trap”, it is a stationary or mobile type of speed monitoring device used to enforce the highway code. On display in Collection 3 – The Gallery of Helpers and also one of the “33 Extras” at the Mercedes-Benz Museum.
Preventive strategy: Cruise control or – even better – limiters can help avoid speeding infractions. Mercedes-Benz assumed a pioneering role with these assistance systems. Simply set the desired speed and cruise control will maintain it. The limiter will prevent acceleration beyond the defined limit.
Rotational movement: By the way, technically speaking the speedometer is a rev counter. It indicates how fast the wheels are spinning on the road. On a side note: most racing drivers do without a speedometer. They focus more on the engine speed and, for this reason, the corresponding display gauge has been positioned in their field of vision. However, they know exactly how fast they are going in fourth gear at 6,800 rpm, for example. Consequently, the dial in racing cars fulfils a dual purpose. Series-production vehicles feature a separate dial to indicate the engine speed.