Inside the instrument, the rotating shaft controls the position of a needle to indicate the engine speed. An electronic tachometer uses a magnetic pickup positioned near a rotating engine part to produce electrical pulses at a frequency proportional to the engine speed.

How does the tachometer work?

It works by bringing a freely spinning wheel in contact with a rotating shaft or disc. The shaft drives the wheel to generate the pulses. These pulses are then read by a tachometer and measured in revolution per minute. It can also calculate the linear speed and distance.

Is a tachometer a speed sensor?

Tachometers and Speed Transmitters require a permanently mounted speed sensors that observe a target on the machines rotating shaft. ... For highly accurate and low speed readings a Speed Gear with multiple pulses per revolution is preferred.