When the car’s spark plugs ignite the fuel and air mixture, it causes the crankshaft to spin. The rate at which it spins and rotates in a minute is known as revolutions per minute (RPM). This speed of the engine is measured by a device known as a tachometer.
Tachometer is often confused with speedometer. Although both of the devices measure speed, the car speedometer measures the rate at which the car is travelling while the tachometer measures the speed of the engine.
In this guide, we will discuss what tachometer is, how tachometer works and different types of tachometer.
What Is a Tachometer and What Are Its Types
A tachometer in cars is a tool to measure the rotation speed of a shaft of a car’s engine or any other machine.
The types of tachometers are as follows:
Analog Tachometers
These tachometers cannot save readings and can’t calculate information like deviation and average. An external frequency to voltage converter is used to convert speed to voltage.
Digital Tachometers
They use an LCD or LED readout instead of dials and needles and are capable of performing statistical calculations. They are best for precisely measuring and monitoring of time-based quantities.
Contact and Non-contact Tachometers
The contact tachometer utilizes a rotating shaft while the non contact one uses a laser or optical disk. The non-contact type is suitable for mobile applications.
Time and Frequency Measuring Tachometers
Time measuring tachometers measure the interval between the incoming pulses to determine speed. They are generally used for low speed measurements. The frequency measurement device, on the other hand, determines speed by measuring the pulse frequency. They are considered ideal for high-speed measurements.
Reading and Using the Tachometer
The tip of the tachometer’s sensor is placed in direct contact with the rotating object. The reading shortly appears on the tachometer. The tachometer is shaped like a semicircle with numbers 1 through 8 on it and a needle that moves as the engine speed varies. For example, if the tachometer needle is pointed at 1, this means that the engine is spinning at a speed of 1,000 revolutions per minute.
How the Tachometer Works
An electronic tachometer generates electrical pulses at a frequency proportional to engine speed using a magnetic pickup placed near the rotating engine crankshaft. An inductive proximity sensor is fitted in the flywheel housing and a magnet is attached to the flywheel. A pulse is generated each time the magnet rotates through the inductive sensor, which is then translated to an electrical signal and displayed on the tachometer.
This concludes our guide about tachometers, types of tachometers and how you can measure RPM with a tachometer. If your car’s engine has low RPM, browse through these used cars for sale in the UAE at reasonable rates.
To learn more about automobiles and automotive accessories, stay tuned to UAE’s leading auto blog.
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