How an Odometer Works and Why It's Needed

When driving, the driver constantly monitors the speedometer, tachometer and fuel level in the tank. But there is another important device, which, although it does not require constant monitoring, nevertheless has great importance, and this device is the odometer. What it measures, what it is needed for, how the odometer works - we will tell you about it in detail. 

Why an Odometer is Needed

Any driver, even a novice, knows that when buying or selling a car, one of the main parameters is the mileage. So, the odometer is a mileage meter. Mileage data, as well as other instrument readings, are displayed on the dashboard. They are available even when you haven't started the engine yet. 

Why do I need to monitor the mileage of my vehicle?

Every driver knows that from time to time the car needs routine maintenance - oil change, cleaning of injectors, replacement of brake disks, etc. The driver determines that it is time for one of these works not by days and months, but by odometer readings. The driver determines that it is time to perform one of these works not by days and months, but by odometer readings. For example, brake disks require replacement when the car has passed about 100 thousand kilometres, cleaning injectors in injector engines is carried out after reaching the barrier of 45-50 thousand kilometres of mileage. The odometer, which is always visible to the driver, allows you to keep track of the mileage.

Odometer readings are important not only during the operation of the car but also when buying a used car. Mileage is basic information that allows you to assess the condition, degree of wear and tear and remaining working life of the chassis and engine at the time of sale. The future service life of the car and recommendations for its maintenance depend on the odometer readings. 

By the way, in modern cars that are equipped with an onboard computer, it is much easier to track the odometer readings. When a certain mileage is reached, the program notifies the driver of the need for maintenance and will show you this message until the necessary work is done.

How the odometer works

The operating principle of the odometer depends on the type of odometer. There are three types of odometers in total:

Let's tell you what they are and how they work.

Mechanical Odometer

This is the simplest type of device. It is a mechanical kilometre counter, which is connected by a cable to the output shaft of the gearbox. The rotation of the cable is transmitted to the meter from several number drums. The number drums are lined up in a row. There can be 5 or 6 of them. The principle of operation of the device is based on the fact that the wheel makes the same number of revolutions per 1 km, which allows you to calculate the mileage by the number of rotations performed. While driving, the wheels spin, and the device counts them and converts them into kilometers. The figures on the device change to form a mileage reading. 

The accuracy of mechanical devices, compared to other odometers, is not very high. The accuracy suffers especially if the driver does not adhere to the manufacturer's recommendations and uses larger diameter wheels. The error in a mechanical odometer can be up to 10%.

Electromechanical Odometer

Electromechanical devices combine the characteristics of mechanical and electronic devices. Here, the torque is also recorded, which is transmitted to the device from the transmission shaft via a cable. However, data processing is carried out in electronic format. An electromechanical odometer is more accurate than a mechanical one. The error in the readings of the electromechanical device is up to 5%.

Electronic (Digital) Odometer

This is the most modern type of device. There is no tether in the electronic odometer device. All readings are recorded and processed digitally by the on-board computer. Readings of Hall sensors and other electronic systems are used for counting. Electronic odometers are considered to be the most reliable and accurate, although they also allow an error within 5%. 

One of the advantages of cars with electronic odometers is the difficulty of falsifying mileage since all mileage data is recorded in the onboard computer's memory. 

How Odometer Readings Are Rolled Back

The main reason for the incorrect mileage of the car remains the deliberate change of odometer readings by the car owner. Unfortunately, some car owners resort to such methods before selling the car for profit.

What is the purpose of the odometer readout:

The buyer always looks at the mileage of the car. He may think that the car has been used little, more standing in the garage, but the previous owner has travelled hundreds of thousands of kilometres on it. 

In mechanical devices, a special device is used to change the readings. The cable is removed from the transmission shaft and connected to a device that makes the cable rotate in the desired direction, and the odometer reading decreases. To change the mileage on electronic meters, special electronic devices and programs are used that make changes to the onboard computer data.

A change in the odometer reading is not only morally damaging. The buyer may suffer serious material losses. In addition, a stranded odometer can prevent the timely completion of maintenance, which in turn entails risks to the operation of the car and safety on the road.

The good news is that today the fact of falsification can always be detected and excluded by checking the car by VIN code. With the help of such a check, you can find out the real mileage, configuration and history of the vehicle. If you need a quick effective odometer check, you just need to follow the link.  

Meaning of odometer readings for a vehicle

The accuracy of many indicators depends on the correct operation of the odometer. The odometer readings, which are recorded in the vehicle's ECU, serve as the basis for many calculations that the ECU provides to the driver. For example, fuel consumption per 100 kilometres. The driver can monitor the final figure on the device or independently select a reference point for control. An increase in fuel consumption per 100 km may indicate a malfunction of the vehicle and will allow to eliminate this malfunction in time. 

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