What is the name of the mileage meter in a car. What is an odometer in a car and what is it for? Types and correction of the device. Mechanical odometers, internal arrangement

The dashboard of a modern car, of course, cannot be compared with the dashboard of an airplane, however, it can confuse an inexperienced driver. The speedometer, tachometer, odometer and other instruments and indicators, of course, are necessary and important, but they still require an explanation of their functions and their purpose. In this article, we will talk about what a car odometer is, what they are, and also say a few words about how and why the readings of these devices are distorted.

Electronic odometer on the dashboard. At the bottom is the total mileage, at the top is the daily mileage, on the right is the button to reset the daily mileage.

If the speedometer measures the speed at which the car is currently moving, then the odometer shows the number of kilometers that the car has traveled. Translated from Greek, odo means road, and meter, respectively, to measure. So in the end we get, such a “price meter”.

The odometer counts the kilometers traveled based on counting the number of wheel rotations. Usually this device has two types of readings. The total mileage of the car, here is considered every kilometer passed by the car from the moment it left the assembly line, as well as the so-called daily mileage. It is called diurnal rather conditionally. In fact, you press a button, reset this scale to zero, after which you can see the mileage of any segment of the path that you have traveled for any time. Well, this indicator is usually called daily by taxi drivers, and this name came from them.

How does an odometer work on a car

What does a mechanical odometer look like on the dashboard

There are only three types of odometers:

mechanical;
electronic-mechanical;
electronic;

Mechanical odometers are more than simple. There is a cable that is connected to the output shaft of the gearbox, there is a mechanical counter with several, as a rule, five drums, to which the rotation of the cable is transmitted through a special mechanism. The drums are marked with numbers, from which the odometer readings are added.

In electronic-mechanical odometers, the rotation of the cable is recorded using an electronic counter. Well, in purely electronic odometers, there is no cable at all. Instead, Hall sensors or other electronic components are used to calculate the distance. At the same time, in the case of an electronic odometer, the readings are recorded by the on-board computer of the car. Such systems are considered the most accurate and reliable, but even they allow a measurement error of as much as five percent.

What does the electronic odometer look like on the dashboard

The reasons for the distortion of the odometer readings can be different. For example, this is wheel slip when they rotate, but the car is stationary. And although such moments make up a tiny part of the overall operation of the car, at high mileage, they can contribute to the distortion of the odometer readings.

Another reason for inaccuracies in the readings of such devices is tires with a radius different from that for which the odometer is designed.

Well, perhaps the most important reason for the distortion of the car’s mileage indicators can be, we’ll talk about them.

Video about checking the odometer reading

Why and how odometers are rewound

The reasons for deliberate corrections of odometer readings can be:

the desire to reduce the actual mileage of the car;
attempts to hide the wrong use of the machine;
elimination of some difficulties with documenting the service fleet;

As we can see, the reasons are mostly not very correct and decent. If you reduce the actual mileage figure, the car can be sold for more. If you rewind the odometer to certain indicators, you can hide the fact that the car drove and sometimes drove a lot when it should be quietly standing in the garage.

However, today equipment is officially produced that allows you to correct indicators even for electronic odometers, which is a very difficult task without special skills and knowledge. Moreover, in a number of European countries, such manipulations are punishable by a prison term and quite significant for such tricks.

The easiest way, from a technical point of view, is to rewind a mechanical odometer. The cable is removed from the shaft, clings to a drill or other similar power tool, after which it rotates in the right direction for some time. But, not all even mechanical odometers allow you to unwind yourself so easily. Then you have to remove the counter itself and perform more complex manipulations with it.

As for electronic odometers, which are the majority today, they are rewound using special devices and software tools that enter the changed data into the memory of the car's on-board computer. In some cases, one or more on-board controllers have to be reprogrammed, because the readings of magnetic wheel speed sensors are transmitted not only to the odometer.

It should be noted that the changed odometer readings not only mislead either a potential buyer or a person who controls the use of the machine, they can be an obstacle to the timely passage of the machine, maintenance, or even the correct diagnosis of certain problems. Therefore, in the vast majority of cases, such corrections are, in fact, fraud.

In modern cars, annoying failures of the main electronics are a rarity. But in a car after five years of operation or in budget vehicles, absolutely any breakdowns can happen. Therefore, technologies that are not always relevant today promise you a cloudless existence and the absence of any problems. A breakdown of such a device as a mileage counter will obviously spoil the mood of the car owner. Knowing the number of kilometers traveled is simply necessary in order to understand fuel consumption and send the necessary data to the on-board computer to display statistics. Even if there is no computer in the car, it is simply necessary to know the daily and total mileage. If you have problems with this process, you should contact the experts and fix the problem. Today we will look at exactly how you can fix problems with this node.

The mileage counter in the car has long ceased to be analog. This is the prerogative of old machines, which can hardly be called reliable. Failure of conventional trip meters is not uncommon, and repair methods come down to replacement alone. In the case of electronic digital odometers, everything is somewhat different. There are a number of points worth paying attention to here. If the electronic counter has stopped counting the mileage, it's time to look into the electronics of the car and get answers to all the questions you have. The manual for the car, a number of simple spare parts and at least a little technical literacy will help to fix the problems, which will allow you to replace the necessary parts to extend the life of all electronic and electrical devices in your car.

Options for malfunctioning the odometer in your car

There are several types of odometer problems. The question is which type has manifested itself in your car. The method used to solve all problems in the repair process also depends on this. You can find out the features of the breakdown by remembering the first manifestations of problems, as well as analyzing the current behavior of the odometer and speedometer. There are several main and most popular ways to troubleshoot the odometer:

the device itself, located directly on the dashboard along with speedometers, simply stopped showing the mileage, the window of the electronic device does not light up, there are no numbers;
the meter shows a certain mileage, the indicated figure has stopped changing, but there is the necessary illumination, this indicates possible problems with the sensors;
periodically the counter comes to life and continues to count kilometers, but it can stop for several minutes or hours, then the device starts working again in normal mode;
both the odometer and the speedometer stopped working, the car does not show speed, does not count the number of kilometers traveled, and other functions of the dashboard may not work;
the backlight of the instruments stopped working at the same time as the normal functions of the equipment were completed, it seems that electricity is not being supplied to this unit.

There can actually be many problems, but today we will talk about the most common ones. Of course, in some cases you will have to spend a very tangible amount of money to restore this function of your car. It is enough just to understand what exactly caused the problem in order to get as close as possible to fixing the problem. However, at times this may not be possible due to the complex nature of vehicle problems.

Replacement or repair of the instrument panel itself in the car

Probably, one of the most expensive solutions for a modern car in this case will be a complete replacement of the instrument panel. And many decide to take this step, since there are no other options. But in fact, the masters at the service do not always tell the truth. Sometimes one revision of the electrical contacts is enough to get the normal operation of all devices. A loose wire can cause a power outage of the entire device. If a replacement is needed, the repair is as follows:

the old instrument panel is disassembled, it is tested, if possible, the possible cause of the problem is found out and even a module that can be replaced;
a search is made for exactly the same model of instrument panel for installation on a car in order to completely avoid inconsistencies in make and model when repairing a problem;
all electrical contacts are checked - you can find instructions for this task quite simply on the Internet or official documents;
then new equipment is installed, all electrical elements are installed without fixing the panel in case there are problems during use;
the next step is to test all the capabilities of the device, and during normal operation of the device it will be enough to put everything back in its original place and enjoy the trip.

Carrying out the procedure for replacing the instrument panel is not so simple. Sometimes for this you will have to disassemble half of the cabin in order to get maximum efficiency and quality. Even dismantling some plastic parts in modern cars can be problematic, so this work is best left to specialists. If you damage any mounting or other parts of the car, you will have to spend a lot of money on restoration.

Replacing the speed sensor at the checkpoint or checking it

In a large number of cases, problems with the speedometer and odometer are due to the fact that the sensor at the checkpoint has broken. The speed sensor in budget cars is completely a consumable item, so its normal operation will end sooner or later. On expensive cars, this device rarely fails, so it can be difficult to diagnose. It is not possible to replace the speed sensor on many machines, but in most cases this is done as follows:

it is worth opening the car’s operating instructions on a page describing the speed sensor, its mounting and location, electrical contacts;
then you should find this device on the gearbox of your car, check the integrity of all connections and wires suitable for it in order to exclude a break;
the next step is to dismantle the sensor and search for a new item in stores - this part may well be a difficult device to find with a rather high cost;
then follows the installation of the device in its original place, connecting the necessary contacts according to the instructions, fixing all the fasteners so that the device is not lost along the way;
the next step is to test all the changes, for this it is enough to get into the car, start it and drive a few kilometers, noticing the operation of the kilometer counter.

All these features can only be used if the speedometer and odometer are broken at the same time. These two elements are completely dependent on the operation of the speed sensor, so their simultaneous stop often indicates precisely such problems. But other unpleasant features that may turn out to be more expensive to solve are not ruled out. However, the most expensive option is to replace the instrument panel with a new part.

Electrical connections are the enemy of car diagnostics

Often, all the manipulations carried out do not give anything, the normal operation of the instrument panel does not appear, the reaction of the car to movement does not change. In this case, it is worth checking the electrical connections. If the malfunction of the instrument panel is manifested by the complete shutdown of the shield, it is worth checking several options and theories on electrical connections. First of all, fairly simple operations should be carried out that can be performed before any repair of this system:

removing the instrument panel and checking for electrical signals in all terminals and connections, this will help to understand whether the sensors are sending the necessary signals to the panel;
then you can find the fuse that is responsible for the operation of the instrument panel with all the elements, replacing it can give an unexpected return to working capacity;
the next step is to check the integrity of the electrical wires supplied to all important elements of this chain, including the instrument panel and speed sensor;
it is also worth checking the absence of breaks in the wires from the sensors to the shield and its components, this factor could disable a number of modules of the shield itself;
Finally, you can disassemble the panel and look at the integrity of the contacts inside, it is quite possible that one of the elements of the electrical board of this module has burned out.

But the system may be too complex for such manipulations. In the case of expensive modern cars, even disassembling and removing some parts will be too difficult. The instructions for such cars rarely describe possible self-service processes. But using the services of a car service in this case can be extremely expensive. The problem is that even removing the instrument panel requires special tools from an authorized service center. We suggest watching a video on how to deal with backlight troubles in the instrument panel:

Summing up

As you can see, the problem of the lack of readings on the odometer is a big problem that requires a serious solution and expensive intervention of specialists. However, do not despair. Even if your car has stopped showing mileage, you can try to solve the problem yourself. You can replace the appropriate fuse, inspect the speed sensor at the gearbox, look for a possible broken wire. After that, you should contact the service, describing the work already done. It is better to buy new parts for car electronics, used solutions will not always be appropriate.

You can continue to drive with a non-working trip meter, but you should find out what kind of problem is associated with this problem. More often than not, you will find that a small investment can completely change the behavior of this piece of car electronics. So it is always worth looking for the causes of problems and fixing all the unpleasant moments that are present in your car. This is a fairly convenient opportunity for everyone to get the necessary qualities of transport operation by returning the factory settings for the service of each node. Have you ever had problems with the odometer in your car?

In a world of minute-by-minute changes and perpetual motion, you have to constantly monitor speeds and distances traveled. As the March Hare said in Lewis Carroll's fairy tale, "You have to run as fast as you can just to stay in place, and to get somewhere, you have to run at least twice as fast." Cyclists also want to keep up with the times. That is why such a device as an odometer for a bicycle is in a hurry to be purchased not only by professional athletes, but also by amateurs.

What is an odometer

A bicycle odometer is a device used to measure the number of wheel revolutions while riding. Modern odometers accurately determine the total mileage of a bicycle, helping the owner to correctly imagine the capabilities of their vehicle. The display of the device shows both the daily and total mileage of the bike.

How it works

Different types of odometers have different designs, but the underlying principle of operation is the same. The following parts of the device can be considered functional:

counter (responsible for counting the number of revolutions of the wheels);
a controller that records the speed (it is directly connected to the counter);
an indicator that reflects the numerical indicators of the distance traveled on the speedometer display.

In mechanical odometers, the force to the cable is transmitted from the drive wheel, which is in close contact with the bicycle tire.

In odometers with an electromechanical transmission, the impulse is transferred along a cable using a sensor to an electronic panel. Electronic models function by receiving electrical impulses.

How does it work

Regardless of how fast your vehicle is moving, its wheels make a certain number of revolutions, passing a kilometer. This figure remains unchanged. Knowing the number of revolutions of the wheel, it is easy to calculate the number of kilometers traveled and display it on the counter. In odometers of different types, counting and transmission occur in different ways.

There are three types of odometers:

mechanical;
electromechanical;
electronic.

Older and slowly fading mechanical models function with the help of a special flexible cable that rotates at the same speed as the wheel. Rotation transmits the output shaft, then the force goes along the cable to the magnetic needle. The magnetic needle displays a numerical value on a magnetized disc.

Pretty simple to complete, a mechanical odometer is relatively cheap. It is easy to disassemble and repair, replacing old parts with new ones. Its work does not depend on batteries and magnetic storms. Meanwhile, with proper installation and configuration, such a device copes with its main function of elementary calculation of kilometers with dignity.

The disadvantage is the automatic zeroing of readings upon reaching a certain threshold figure. In addition, the mechanical device somewhat complicates the rotation of the wheel, and if the wheels are bent in a figure eight, it does not work at all. Dirt that gets on the device can also affect the meter readings. So such an odometer must be frequently and thoroughly wiped and lubricated. But for walking on a clean and smooth highway, a device with a mechanical transmission is quite suitable.

Electromechanical Odometers work by rotating a gear that drives force to an electromechanical sensor.

The sensor device generates pulses of electricity that are sent through wires to the speedometer unit, where a small electric motor rotates, acting as a drive for the mileage counter. Odometers of this type are installed on most modern cars.

Electronic odometer sensors are fully electronic. In addition, they have liquid crystal indicators. Such a device is more difficult to "deceive", for this you will need to use a special device.

Modern bicycle odometers, in fact, are becoming part of the "on-board" bicycle computers, calculating not only the total mileage of the bike, but also many other movement parameters necessary for cyclists who are seriously engaged in cycling. These can be, for example, indicators such as:

current speed;
average speed;
distance length;
travel time;
cadence;
mileage;
watch.

The sensor of the electronic odometer is a contact hermetically located in the housing - a reed switch. It is fixed on the feathers of the front fork or (when the length of the wires is sufficient for this) near the rear wheel. A permanent magnet is attached to the spoke of the wheel, which causes the sensor to work. The time between the next two sensor activations is monitored by the microcontroller. Liquid crystal indicators with seven segments reflect the result, the backlight function is performed by LEDs.

Are there errors in the operation of bicycle odometers

Like any device, an odometer can have an acceptable percentage of errors. Mechanical devices mounted on mountain bikes or bikes moving on rough terrain can give up to 15% errors. It is believed that the more severe the operating conditions of the vehicle, the higher the error. For example, slipping, weakening of the flexible cable (it must be taut, it must not be allowed to sag in the loops), loosening of parts can adversely affect the operation of the odometer. True, such a high distortion rate is still not typical for new generation bicycle odometers. Electromechanical devices can give up to 5% distortion. But digital gadgets, in which there are no mechanical connections between parts and the risk of internal damage is minimized, give no more than 1% of errors.

How to choose the right device

If you have clearly decided that you need a bicycle odometer and will not become another toy idly hanging on the steering wheel, before installation, first of all, you need to choose a high-quality device that will not have to be thrown away after the first cycling season.

When choosing an odometer, it is necessary to take into account such parameters as:

reliability of the device;
indication limit;
case quality;
functional;
attachment type.

The most reliable bike meters are produced by companies such as VDO, BBB, Cateye, Sigma. You can choose a model individually, based on the goals that you set for yourself.

Odometers are divided into models with a maximum speed of 99.9 km / h and devices that display three-digit indicators. For example, the Sigma 506 speedometer shows speeds above 100 km/h. This device is designed for cyclists. Fans won't need it.

The size and compactness of the devices may be different, but the functionality does not depend on this. You can even purchase a device in the form of a wrist watch that measures the athlete's pulse.

You can also mount the bike computer on or on the steering wheel itself. There are devices with a universal mount.

The ideal odometer model should have a large display with clearly readable numbers.

It is necessary that the device withstand vibration and harsh weather conditions, and its components must be distinguished by the build quality.

How to set up an electronic odometer

Starting the installation of a bicycle computer is, first of all, correctly specifying the parameters of your vehicle. It is best to do this immediately after purchasing the bike. It is best to record and save the indicators.

First you need to set the indicator C - the length of the wheel. It needs to be clarified, since this number is non-standard. To do this, we measure the perimeter of the tire using a centimeter tape wound around the wheel in a circle. Another way: put a bright mark on the wheel with paint and, having rolled the bicycle one revolution of the wheel, measure the distance from one print to another.
Then you need to use the wiring to fix the sensor on one of the feathers of the fork or on the bicycle frame.
Next, tightly wrap the wire around the pen and the brake cable.
We install a mounting platform on the steering wheel or steering wheel.
We fix the magnet on the spoke, but do not overtighten the screw so as not to break the magnet. There should be no more than 3 mm between the magnet and the sensor.
We fix the bicycle computer in the contact area and check the quality of work.

A bicycle odometer is a necessary device in the life of every modern cyclist. With the skillful use of the device, it is possible to predict the timing of maintenance in a timely manner, correctly distribute sports loads, and comfortably travel long distances while cycling. A well-chosen and reinforced odometer makes life on two wheels easier and increases your chances of staying on track.

Many of you have heard the phrases of motorists “what is the mileage on the speedometer”, “wind the speedometer”, “speedometer twist”, “speedometer winder”, “speedometer adjustment”, “speedometer winding”, “how to wind the speedometer”, but only a few know that the word speedometer is used in these phrases erroneously. The speedometer and odometer are two completely different measuring instruments, one of which determines the instantaneous speed of the car, and the second mileage in kilometers or miles. Therefore, it is correct to say not “wind up the speedometer”, but “wind up the odometer”, “adjustment of the odometer reading”, and not “adjustment of the speedometer”.

The speedometer was invented about a hundred years ago, at the dawn of the automotive industry. Who was the inventor of the first speedometer is unknown. It is believed that the first speed measuring device was installed on an Oldsmobile car released in 1901. According to other sources, the first speedometers were installed by FORD MOTOR Co. on their cars in 1910. Some historians believe that the invention of the first speedometer belongs to the famous inventor, physicist, engineer Nikola Tesla, who filed a patent for invention No. 1209359 in 1916. The design of the speedometer for a hundred years has not changed much, with the exception of some modern car models.

Who invented the odometer is not exactly established. Some scientists attribute the invention of the odometer to the ancient Greek mathematician from Syracuse - Archimedes (287-212 BC), others - to the Chinese scientist and inventor Zhang Heng, others - to the Greek mechanic and mathematician Heron of Alexandria (10-70 years . BC.). Mentions of the first odometer can be found in the chronicles of the 1st century AD. He was a cart. The size of the wheels was mathematically calculated and at a turnover of 400 times measured exactly 1598m. The gear transmission of the device was set in motion from the wheels of the trolley, the distance counter was small pebbles falling into the tray of the trolley. With the development of electronics, the design of speedometers and odometers was also improved. Modern dashboards work on slightly different principles. Electrical signals - pulses from ABS sensors, speed sensors are sent via CAN bus to the dashboard processor, processed and reflected in the form of readings on the odometer.

Odometers allow you to accurately determine how many revolutions a car wheel has made. Knowing the number of revolutions of the wheel, the microcircuit or processor calculates the distance traveled. Most often, odometers are electrical, mechanical or electromechanical. The odometer shows both daily and total vehicle mileage in kilometers and miles. This data allows you to accurately determine how far the car has traveled for a certain period of time and for the entire period of operation. Information about the mileage is displayed in a digital value on the dashboard of the car.

Mechanical odometer. The design of the mechanical odometer is simple and reliable. Under the influence of mechanical force, the counter counts the revolutions of the wheel and converts them into the distance traveled. When a certain extreme mileage figure is reached, the mileage is reset to "0". The mechanical odometer is wound up with any "twist".

Electronic mechanical odometer. Wheel revolutions are read by a speed sensor based on the Hall effect. When the car is moving, the sensor generates pulse signals at regular intervals. For one kilometer of the way, the speed sensor transmits about 6000 signals to the electronic side of the speedometer. The data is converted into digital format and displayed on the dashboard of the car. To wind up the mileage on an electronic-mechanical odometer, you will need a CAN-twist.

Digital odometers are state of the art. All information coming from the sensors is processed by the microcontroller. It requires special equipment to correct it.

Dashboards, odometers and speedometers on modern cars work on different principles. On some dashboards, an electrical signal is received via the CAN bus in the form of an impulse from a speed sensor based on the Hall effect, on other panels from ABS sensors.

Modern equipment allows you to correct odometer readings on cars, trucks, motorcycles, snowmobiles. The time and price of the adjustment depends on the model, year of manufacture, the complexity of the preparatory work (removing the dashboard, disassembling the speedometer, removing the arrows), etc.

Regardless of how exactly the speedometer shows speed, it is considered one of the most important devices in a modern car. We are forced to look at his testimony, otherwise it will not be possible to avoid punishment for violations of speed limits in force on the territory of the country.

What is a combination speedometer / odometer

The combined instrument indicates the driven speed in the car, measures the distance traveled, shows the distance traveled per trip and the instantaneous speed.

Attention! The value of the speedometer scale helps the driver determine the timing of the replacement of engine fluid and filters and calculate fuel consumption.

The speedometer is equipped with an odometer - a mechanism that measures the number of revolutions of the car wheel. Thus, the mileage traveled by the car is revealed. It is possible to calculate the daily and total mileage.

The odometer consists of:

counter of the number of revolutions of the car;
an indicator showing the distance traveled in km or miles;
speed recording device.

The odometer is classified into the following types.

The mechanical device is considered the progenitor of modern devices. It was invented in ancient Greece.
Twisting such an odometer is as easy as shelling pears, it is enough to act on the torsion mechanism. The mechanical odometer counter reacts to revolutions and converts them into kilometers. However, the disadvantage of such a device is the spontaneous zeroing of data when a certain value is reached.
Combined odometer - an improved model that makes it possible to correct data using a CAN-twist.
A digital device operating on the basis of a microcontroller. Everything in such an odometer takes place in a digital way, and it is possible to influence the readings of the device only with the help of highly professional equipment. Electronic odometers are part of the car's on-board computer system.

The principle of operation of the speedometer is clearly visible on the example of a mechanical device. The change in speed is carried out due to the mechanical connection between the gear shaft and the arrow. Both elements are connected by a cable of sufficient length, since the shaft is located far from the transmission. Its speed is due to the finite amplitude of the rotation of the wheels.

A special gear in the main gear rotates with the output pulley and is also directly connected to the cable, enclosed in a special protective casing.

Another obligatory element is a disc-shaped magnet placed next to a steel drum. The latter is fixed on the needle, and the obtained indicators are displayed on the scale.

Even the electronic odometer has inaccuracies. They cannot be excluded, so it is customary to take into account certain standards that allow a limit to this value. For example, on a mechanical device, the error should not exceed 5% -15%.

Device errors are due to the presence of various gaps, cable weakness, poor grip and weak springs. More errors are produced by a mechanical odometer, digital - much less, because it is possible to read the readings of the microcontroller, sensor.

The error also happens on the speedometer, which calculates the speed of the car. The device is simply unable to display ideally accurate information, since the speed depends on several components: the rotation of the wheel, its diameter, etc.

It will be interesting to follow the errors of the device at different speeds.

60 km / h - there are almost no errors.
110 km / h - the error is 5-10 km / h.
200 km / h - the average value reaches 10%.

The error also varies according to the following points.

On cars with front-wheel drive, the error manifests itself, almost at every turn. The reason is that the speedometer is integrated with one wheel. Because of this, turning to the left reduces the readings, to the right - increases them.
The error is affected by the non-standard size of the wheels. A difference of 1 cm increases the error to 2.5%.
Tire diameter is important. At the slightest discrepancy with the standard, the speedometer readings are underestimated or overestimated.
Tire pressure and tread wear can affect the error. For example, if the wheel is poorly inflated, this leads to an underestimation of the maximum speed.

The most accurate readings, as mentioned, are given only by a digital device or a device connected to a GPS navigator. The benefits of satellite positioning cannot be underestimated. Modern systems show the exact speed of the vehicle without any errors.

The standard speedometer is marked with a scale of 10 km / h, and its needle twitches on bumps. He can only overestimate the testimony, but not underestimate. Otherwise, the traffic situation will be falsely assessed and an emergency will occur. For example, if 100 km/h is displayed instead of the real 120 km/h.

A few words about the errors associated with tire sizes. This is where the design of the speedometer comes into play. It consists of two devices combined in a single housing. One device measures the speed, the other - shows the mileage of the car. So they are called: high-speed and counting nodes.

Now specifically: if the car is shod in rubber, well-worn, the speedometer will overestimate the readings, since the gradation system comes into force every 10 km / h and the law of rounding numbers used in odometers.

Differences: speedometer and odometer

The mileage counter is mounted directly into the speedometer itself. For this reason, it seems to many that the device is a single device. In fact, this is not true: