how to read tachometer & speedometer in car

how to read  tachometer & speedometer in car

About the view and meaning of the car tachometer

There are various instruments on the instrument panel of the car dashboard.

I often check the speedometer for speed check,
Many people may not be familiar with the functions and perspectives of tachometers.

Here, we will introduce how to read and mean the tachometer of a car.

Where is the tachometer in the car

Usually, the tachometer of a car is
It’s next to the speedometer in the instrument panel on the dashboard.

Some models do not have a tachometer, some are built into the A-pillar,
Some models have an independent speedometer.

How to read the tachometer

The car’s tachometer shows the engine speed.
The tachometer has a scale starting from 1, and the number x1000 is written in the meter.
The engine speed is calculated by multiplying the number on the scale by 1000.

Generally, the tachometer points to a little less than 1000 rpm when idling.
If this value is extremely strange or unstable,
Be aware that your car may be defective or malfunctioning.

The clutch can be engaged at an appropriate number of revolutions, preventing wear on the clutch and tires, which is very convenient.
the engine speed may be controlled automatically when driving,
Some models do not have a tachometer.

How to use a car tachometer

Once you get used to it, you can drive with the sound and feeling of the engine,
You can drive smoothly by driving while looking at the tachometer.

The engine speed shown on the tachometer also indicates the condition of the engine.
If you check it on a regular basis and an abnormal number of revolutions is shown,
You can detect and deal with engine defects at an early stage.

Also, if you control the engine speed well, such as by consciously using high gears,
It leads to eco-driving and can improve fuel efficiency.
If you increase the speed and reduce the engine speed, you can achieve fuel-efficient eco-driving.

In addition, if you drive while looking at the tachometer, you can see your driving habits numerically.
How much the engine speed is increased when starting or driving on a slope, etc.
Understanding the numbers will improve your driving skills.

Furthermore, on wet or frozen roads, select the gear while checking the number of revolutions.
It is also useful for safe driving, such as adjusting the degree of depression of the accelerator.

By all means, know the view and meaning of the tachometer and remember that there are various merits.
Check the tachometer of your car and make good use of it for daily driving.

Car tachometer principle of operation and types

Such a device as a speedometer is found on all modern cars. Many inexperienced drivers don’t even know what it’s for. A car tachometer is one of the key devices, its readings are just as important as the speedometer readings or, for example, the engine temperature readings.

What is a speedometer?

Speedometer is measuring device, designed to measure car crankshaft speed. Such a device is installed not only on cars, but also on motorcycles, motor boats and other vehicles. The speedometer is also used in industry, for example, to determine the speed of the steam turbine.

The speed of rotation of the crankshaft is measured in revolutions per minute. On modern imported and domestic cars, the abbreviations RPM, “r / m” and min-1 are used. In analog or analog speedometers, the numbers are arranged in a circle, most often from 1 to 9. These numbers must be multiplied by 1000 to find out the exact rotational speed of the crankshaft.

Why car speedometer?

The car’s tachometer determines the speed of the engine, but why is it necessary to know how often the shaft rotates? Thanks to the tachometer, you can find out the condition of the car’s engine. The usable motor runs on single revolutions with the same frequency. The normal crankshaft speed on the engine is approximately 1000 revolutions per minute. If, after starting the engine at idle, there will be strong fluctuations in the arrow, for example, from 500 to 1500 rpm, then the car is out of order. But further driving the machine with defective coils can lead to serious consequences and costly repairs.

The car’s tachometer has another important function. On each speedometer there is a red zone, it most often starts with 6-7 thousand revolutions. This zone warns that the engine is running at full power. Due to a long journey at maximum speed, the engine cannot hold up and collapse. Therefore, it is necessary to closely monitor the speedometer readings.

Experienced drivers often use a car tachometer to save fuel. After all, as you know, if the engine runs at high speed (3500-5000), the fuel consumption increases. Therefore, do not load the engine and move it with a rotation speed of no more than 2.5 thousand revolutions.

Principle of operation

Most modern cars use digital and electronic speedometers. The principle of work is the same for everyone. Next to the crankshaft, a sensor is installed that measures turns. Through special wire readings are transmitted directly to the speedometer. The display shows the number of turns of the arrow.

Older cars also used auto speedometers. Mostly mechanical or analog. The data transfer process was different. It also used sensors, wires, electrical circuits and a magnetic coil. The coil collected energy from the movement of the crankshaft, thanks to which the speedometer needle moved and the readings were transmitted to the dial.

Digital and analog speedometers

The digital speedometer of the car is made in the form of an electronic display, on which readings are made, that is, the number of revolutions of the crankshaft of the engine. The digital speedometer is particularly useful if precise adjustment of the idle or the adjustment of the engine ignition device is required, even for the correct installation of an economizer. The economizer is a device that serves to enrich the combustible mixture with gentle acceleration or, conversely, with a strong pressure of the accelerator pedal.

The arrow of the car speedometer more often can be seen on the dashboard. For many drivers, it is convenient due to the fact that the speedometer readings are transmitted to the usual hand, which moves on the dial. As practice shows, the human brain is better perceived by arrow information, rather than electronic.

Electronic and remote speedometers

Electronic tachometer The automotive sector has the same principle as digital. The display often uses a scale. Instead of a magnetic coil, an electronic sensor is used that transmits a signal to the display. The electronic car speedometer can be used as an additional device to measure the number of revolutions. This is necessary if the standard speedometer has an error or more accurate readings are required. For example, not all models of the WHA (up to 2000) were installed regular speedometers.

After completing the engine overhaul or installing a turbine on it, you will get that the engine speed will increase. The standard device will not be able to show reliable information. To do this, you will need to install a remote car speedometer. This can be done temporarily or left to compare the readings with a standard speedometer.

Recently, tachometers have appeared that can measure rotational speeds in a non-contact manner. A speedometer of this type is often found in auto services. The principle of its operation is as follows: next to the motor shaft, a piece of reflective film is attached to which the laser beam is directed. Measure the time during which the tree passes one full revolution. Afterwards, the signal is transmitted to the speedometer and the readings are displayed on the instrument.

If you want your speedometer to serve you for many years, you have to put a lot of time and effort into it. You have to choose very carefully. Branded devices will cost you dearly, but the quality of the goods will be on top.


In summary, it should be noted that the speedometer in your vehicle is an indispensable thing. With the car tachometer we know the engine speed. This testimony provides information that everything is in order. Running at moderate speeds will help save fuel and extend the life of your engine. Don’t forget to respect your favorite car.