A speedometer is an essential part of any motor vehicle because it measures the speed of the vehicle. Analog devices have been used to measure vehicle speed for nearly a century, until electronic speedometer technology became readily available. These devices offer greater accuracy and reliability than older models, but maintain the common layout of traditional speedometers. In addition to speed, the electronic speedometer can measure revs and even distance traveled with digital precision. Today, such devices are found in many wheeled and non-wheeled vehicles.
The electronic speedometer also provides very accurate odometer readings. A speedometer is a device that measures the speed of a vehicle, usually by moving a hand along a circular path, such as a clock hand, showing how fast the engine is pushing the vehicle. The first speedometers were used in the early 20th century and had a spinning cable on the transmission of the engine. Electronic speedometers, first used in the 1980s, may look like traditional speedometers or digital LCD screens. It can also take readings from the transmission, but in a completely different way.
An electronic speedometer can measure the air speed on an aircraft. Electronic tachometers rely on electronic rotation sensors mounted near the engine transmission. The sensor is usually a toothed metal disk mounted between the coil and the magnetic field sensor. When the engine is running, the magnetic field sends a pulse to the sensor. The pulses sent correspond to the rotational speed of the drive shaft. This data is fed into the speedometer's internal computer and calculated by converting the tach to miles or kilometers per hour. Modern speedometers do not rely on analog methods to read the rotation of the driveshaft, so these devices provide more accurate readings. Another advantage of an electronic sensor compared to a rotating cable is that it has a lifespan because conventional speedometers wear out faster. The electronic speedometer also provides tachometer and odometer readings with the same accuracy. For these reasons, many older vehicles traded analog models for electronic speedometers. Electronic speedometers are often considered part of cars and trucks. This is true because almost all modern cars use electronic speed measuring devices, but it's not the only place these tools are used. Electronic motorcycle tachometers are another common sight on two-wheeled vehicles. In addition, airplanes use these tools to accurately measure air speed, as do motorboats.