Speedometer ... About this device, of course, knows any motorist. However, what is an odometer in the car - not everyone can answer, and this is quite natural, because this device is far from being so simple and primitive, as it seems at first glance.
At the same time, not everyone see the difference between odometer and speedometer - a completely different device combined with it. Well, we will try to intelligibly talk about differences, as well as what it is - a car odometer.
Principle of action of odometer
Expressing scientific language, odometer is a mechanical or electronic devicedetermining the number of revolutions performed by the wheel, that is, the counter. Thanks to this information, the car owner can determine the path that passed the car over the entire period of its operation or for a certain period of time. That is, the information received by the device is communicated to the driver in a numerical form, and specifically - kilometers through the path.
The principle of action of the device is such - for one car traveled kilometer the wheel makes the same number of revolutions. Knowing how many revolutions it made in general for a particular path, it is easy to calculate kilometers traveled, and it is it that is displayed on a mileage meter.
In addition, resetting the odometer data before the trip, you can easily set the distance from the point and to the point B either to calculate how much the car drove at one fuel dressing. About all these functions of the odometer knows probably any driver.
These types
Despite the fact that the car is an invention relative to the recent past, such a device as an odometer was known for a very long time - Heron is his inventor. It is quite logical that the first such mechanism was mechanical.
Actually, in the automotive industry, all the initially used odometers had purely mechanical design, And the meter itself, which is on the dashboard, was a set of drums with applied numbers, which changed as the car passed a certain distance (one kilometer or mile).
Such odometers were distinguished by simplicity of construction and reliability, but had several significant flaws. The main one was the limitation of the mechanical meter - when it was reached a certain mileage, it was reset.
In addition, the accuracy of such an odometer was achieved only when using the wheels on the vehicle strictly defined dimension, and the deviation from it caused a serious error in measurements.
In the middle of the twentieth century, automakers began to use electromechanical counters, which, receiving information from a mechanical sensor, output noted with the help of archaic drums with numbers, and on a liquid crystal display.
Later, completely electronic odometers were created, which received information about the wheel turnover from the so-called Hall sensor. At the same time, the information coming from it was processed by the car onto board and stored in his memory, which made it possible to maintain information not only about the total run, but also separate trips.
It was very convenient, for example, for measuring fuel consumption or distance traveled in several trips.
Odometer and speedometer: What is the difference?
As we have said, not everyone knows about the difference between two completely different devices - odometer and speedometer. Many misleads the fact that the odometer scale is practically integrated into the Speedometer testimony scales.
It is logical that some quite reasonably suggest that this is the same device. In fact, the difference between the devices is very significant.
Speedometer serves to measure the speed vehicle And it is not associated with the functions of the odometer - the meter passed by the vehicle of kilometer.
Combining the scales of these devices is due only to the convenience of perceiving information by man, as well as tradition. However, today the indications of the odometer are displayed on the display on-board computer Among the basic information, this display is still located in the area of \u200b\u200bthe Speedometer scale. However, these devices cannot be confused.
Using a odometer in determining the mileage of a used car
It is well known that the odometer is the main means by which you can set the mileage of a vehicle. This criterion is one of the most important, since the kilometer passed allows you to evaluate the general technical condition Car, degree of wear of nodes and aggregates, as well as the residual resource of the engine.
Of course, that many motorists operating with their own vehicles often arise a desire to change the odometer testimony in order to increase the initial cost of the car sold.
We will leave aside the moral and ethical side of this issue and see how real in technical Plan "Twist" odometer counter.
Here we should again deepen in the history of this instrument. The first, mechanical, odometers had a serious drawback - to change their testimony was quite simple. In essence, this reason has forced the automakers to search various methods data protection, which, as a result, led to the creation of electronic devices.
In them, as we have already written, information about the common mileage is "sewn" in the onboard computer of the car, and it is much more difficult to adjust it. In practice, send an electronic odometer in minus is still possible, but this is not done by no interference with the operation of mechanical nodes, but by rewriting in the memory of the onboard computer laid information in it.
Video - Pro twisted runs for cars:
Today on the Internet there are many proposals in this area, which is at least a well-known site odometer. RF, which are talking about the relative simplicity of such a procedure.
But do not forget that in most modern cars Information about mileage is stored immediately in several independent of each other electronic blocksAnd it is quite capable of identifying the fact of the "twisting" of the testimony of the odometer from the motorist.
conclusions
As we see, get the answer to the question of what an odometer is, not so difficult. Knowing the principles of the operation of this Assistant motorist, it is easy to obtain information about the path traveled, learn the total mileage of the car, control fuel consumption. Of course, it is one of the most significant devices of any vehicle.
Video - Is it possible to know whether the mileage (odometer readings) is twisted - the tips of the repayment.
What is odometer? This is a fairly accurate device designed to measure the speed of the automotive wheel. With the help of odometer, the path is measured that drove the car. The number of wheel turns is considered to be the device and is converted to indication on the indicator.
The odometer consists of the following parts:
The sensor that is associated with the wheel and fixes turns;
A counter that produces revolutions;
A indicator that shows no number of wheel speeds, and the path that car drove.
Odometer can be:
Mechanical, where the rotation of the wheel using mechanical connections is transmitted to the meter, which, too, under the action of mechanics, considers turns and translates them to kilometers and meters.
Electronically mechanical, where the reading of the wheel turns occurs with the help of mechanics, and the meter then converts turns into electrical signals, which are then displayed on the indicator.
Electronic (digital), where all removal of parameters and their conversion into visible indicators occurs in in electronic format. Most often, such a odometer is one of the elements of the on-board computer system.
Odometers do not belong to the category of devices with a high accuracy class. It's just there is no need. They operate with categories of meters, kilometers. Therefore, these devices are characterized by certain errors. And these errors are often not dependent on the device itself, but rather from a certain wear of the car. And the older the car, the errors will be more.
For a new car with a mechanical odometer, a normal error can reach 5%. But as a result of operation, changing road conditions, replacement and wear of some parts, the error of the mechanical odometer may increase to 15%.
The classic example of such an error is to slip the car wheel. Formally, the car goes a little, but the wheel rotates. It should be borne in mind that the error is set specifically for a odometer as such. But it does not take into account the possible change of car parts, which can also give a certain percentage of error. Various backlays, weakened springs, deformation of the cable, friction - all this makes a tolik in the end readings of the odometer.
Electromechanical devices operate on the principle of counting pulses outgoing from speed sensor. There is a counting of impulses per unit of time. Odometers of this type have greater accuracy and less error than mechanical instruments. And their error does not go over the mark of 5%. In rare cases - 7%.
Electronic (digital) odometers have the lowest error. This is due to the fact that they do not have mechanical details that are subject to wear. But exercising control of the path traveled, their sensors read information from mechanical parts for which wear is quite a natural phenomenon. Therefore, the error is still present.
To the question "What is a odometer" can be answered and otherwise. Odometer is one of the devices for a certain diagnosis of the state of the car. After all, the first thing that is asked when buying a non-car car, is what mileage? And then there are other questions.
The mechanical measuring device of the distance we took as the basis for this article has a gearbox 1690: 1! This means that the input shaft must be checked for 1690 times before 1 kilometer appears on the scoreboard. Odometers like this currently replaced with digital speedometers that provide more possibilities And it is less, but they do not go to any comparison with real odometers. In this article, we will consider every little detail of this complex mechanism, and then talk about how digital speedometers work.
Mechanical odometers, internal device
Mechanical odometers rotate a flexible cable that is made of a tight twisted spring. Usually the cable rotates inside the metal tube in the rubber case. On a bicycle, a small wheel rotates in the opposite direction from the wheel, thereby leading the cable in motion, and ratio On this device should be calibrated in accordance with the size of a small wheel.
In the car, the cable rotates the output shaft of the gearbox. The cable is connected to the dashboard, where it is connected to the inlet shaft of the odometer.
Gear
Odometer itself uses a series of three worm gears (worm transmission - mechanical transmission, engaged in the engagement "worm" and the worm wheel conjugate) to achieve the gearbox of the indicator 1690: 1. The inlet valve leads to the movement of the first "worm", which leads to the movement. Each full turn of the "worm" turns only one tooth. The same mechanism leads to the movement of the next "worm", which turns another transmission, which, in turn, leads to the movement of the last "worm", which is connected to the odometer indicator and turns the digit with the tenth miles.
Each indicator has a number of studs sticking on one side, and one set of two studs sticking on the other side. When a set of two spills is suitable for a white plastic gear, one of the teeth 
It falls between these studs and turns along with the indicator, until the studs go further. In this mechanism, one of the indicator studs with a large number is also involved and makes 1/10 of its turn.
Perhaps now, you can understand why when your speedometer "raises" (for example, showing the figure from 19,999 kilometers to 20,000 kilometers), the "two" digit on the left side of the display may not be on the same level with the other numbers. It's all about a small amount of small studs that prevent the perfect alignment of all numbers. As a rule, before the figures are lined up into the correct row, at least 21,000 km should be on the speedometer.
You could hear that mechanical speedometers can be rewinded. It is so, because by themselves - these are gears and when moving a car back it will also rotate in the opposite direction. But you do not need to go hundreds of miles back in advance, you can only connect the cable to the drill and clear so much kilometers as you need. If you served in the army as a driver's posts, then this method of twist the machine run, a bush, should be known to you. If the army boots came to you not to face, it never studies late. If it is impatible, of course.
Everything that works with a mechanical distance meter will not pass with digital and you will be sure to read the next part of our article.
Digital or computerized odometers. Internally, how does it work?
If you take a walk on bike shops, most likely that you will not find a single bike equipped with a odometer (or speedometer) with cable control. Instead, you will find cycling computers. These bicycles have a magnet attached to one of the wheels, and the sensor is attached to the frame. Each time the wheel makes one full turn, the magnet passes by the sensor, creating a voltage in it. The computer counts these voltage bursts, or impulses, and uses them to count distance.
If you have or had a bike with a similar computer, you should know that it must be programmed on the wheel circle. The circle is the distance traveled by the wheel for one full turn. Each time the computer feels the pulse, it adds the wheel circle to the total distance and updates the digital display.
Many modern cars use a similar system. By the way, an article about a couple of such modern innovations from Volkswagen you can read. Instead of a magnetic sensor on the wheel, this system uses a gearbox installed on the gearbox input shaft, and a magnetic sensor that counts pulses each time one of the wheels is passed by. Some cars use slotted wheels and an optical sensor, exactly the same as in computer mouse. Just like a bike, the computer knows what the distance the car passes between each pulse, and uses it to update the odometer readings.
One of the most interesting things in the automotive odometer is how information enters the dashboard. Instead of a cable that transmits a signal in a mechanical sensor, in digital information about the distance (together with other data) enters the dashboard through the connection wire from the engine control unit. The car is a local network to which connected various devices. Below we bring a list of some of the devices that are connected to a car computer:
- The engine control unit
- Climate control system
- Dashboard
- Control of the hydraulic power steering
- Radio
- Anti-lock brake system
- Inflatable airbag control unit
- Control unit (operates with interior lighting, etc.)
- Gearbox control unit
Many cars use a standardized communication protocol, SAE J1850 to enable all electronic modules to communicate with each other.
He considers all impulses and tracks the total distance traveled by the car. That is why it is impossible to "unscrew" 
digital odometer back, because The value that is stored in the engine control unit will not match the desired, and this is not possible. This value can be checked with computer diagnosticswhich is in every service center official dealer. So, if you, for example, are standing on the verge of buying a used car and tormented doubts about too small running on its instrument panel, know that the appeal to one of the less decent hundred will be able to help you with the test of the "white" run Auto. But back to our "Baranas". Several times per second, the engine control unit sends a packet of information consisting of a header and data. The title is just a number that identifies a package as a distance reading, and the data is a digit corresponding to the distance traveled. The toolbar is another computer that knows that he needs to look for these packages with information and, as soon as he sees one of them, he immediately updates the odometer with new values. In cars with a digital odometer, dashboard Just displays a new value. Cars with analog odometers are equipped with small stepping motors that turn the numbers on the odometer.
If your speedometer or tachometer on the VAZ, Gazelle, Toyota, Nissan, Mitsubishi or another car brand, has failed, do not despair. Always happy to help you. You can find and buy such goods as a digital speedometer, speedometer cable, speedometer arrows, tachometer and much, much more. This requires only to leave a request on the site, after which dozens of auto shops will come to you with your suggestions.
If you want to pose a car enthusiast, ask him what is the odometer or where it is located in the car. Despite the fact that it is resorted to his help regularly, not everyone knows how it looks. This is a significant device that is in each vehicle operating on the internal combustion engine.
Judging by the title, you can already determine that this is a measuring device, like a tachometer or a digital speedometer. Odometer measures the number of kilometers traveled.
Purpose
The task of the appliance odometer is to transfer the testimony about car mileage. Thanks to such information, the driver without problems can establish the actual distance from the point of departure to the destination. Such readings will help not only determine the fuel consumption different conditions, but also to replace the necessary parts and components in time.
Among other things, the odometer can benefit its testimony and during the purchase of a used car. When examining such a car, an appropriate desire to learn how it was exploited. Odometer will help you to find out how many kilometers was passed on this car.
Since the difference in price directly depends on the mileage of the machine, then many sellers appear temptation to hide the truth in this matter. Not wanting to present the actual testimony of the meter, such people twist mileage, putting the facts changed by changed readings. In view of this, the question arises: how to determine if there was an adjustment of the indication of the run or not? What to pay special attention When finding out this issue?
Principle of operation
Odometer is three types: mechanical, electronic and, transitional option, is semi-electron.
The odometer is calculated using a special sensor, which is located directly, in the variable transmission box. The incoming impulses are submitted to the counter, which provides indications. Consider the principle of operation of each type.
Mechanical
This type of measuring device is designed exclusively from mechanical parts. In the gearbox is located its measuring part - gear. Rotating, it leads the flexible cable connected to it. The cable, in turn, transmits the rotation to the counter, which provides the testimony of the Odometer done Putin.
Semi-electron
As the name is from the name, the device consists half of mechanical nodes and from electronic. From the mechanics there is a measuring part of the node - gear and cable. In the meter itself, there is a conversion of incoming information: the ropes of the cable turn into electrical pulses and the data is displayed on the reading panel.
Electronic
Digital technologies - an integral part modern car. Therefore, the odometer in such a car should also be digital. This type of meters does not use the mechanics at all.
All of its device is based exclusively on sensors that transmit electrical pulses for processing, after which you can see the result.
Subject of indications
In a mechanical odometer, a change in the testimony is not much labor, so even an inexperienced mechanic will be able to perform such a procedure. This is followed as follows: The cable transmitting readings on the meter is disconnected from the gear in the PPC area. Then it is rotated in reverse side. For these purposes, it is usually fixed in the cartridge of the electric drill. After performing the operation, the cable join back to the gear and odometer is assembled.
It was pretty easy to notice anything on the car. To do this, you will need to drive the car to the observation pit. There carefully look at the place of connecting the cable with gears in the checkpoint. The difference will be obvious. If all the elements of the odometer are in dirt or dust, and the location of the cable connection with the gear is relatively clean, then it is clear that it was not without fraud.
With a semi-electron device, the situation is much easier. To this end, the instrument layout panel is removed and opened the housing of the meter itself. Further, the gear disconnection of the reading mechanism is separated and the required value in a short period of time is exposed.
To identify such intervention will also not be much labor. When inspection, you should pay close attention to the location of the hull connection. During the opening, not avoid damage to these elements. Yes, and on the places of screw connections, such intervention will be clearly noticeable.
As for the electronic meters, it was not without vulnerable to fraud. The readings on them can also be changed. But this procedure is not easy and requires not only certain knowledge, but also special equipment with software. In certain cases, it is still necessary to tinker with disconnection of boards in devices, or make an additional soldering.
It is almost impossible to identify flashing electron odometer. The exception is only cases when the instrument panel disassembled. But do not be upset, because the testimony of the odometer is not the only criterion by which you can determine the degree of vengery of the car. Persistently examining the condition of the elements or housing in the car, you can detect interesting details of the state of transport.
Well no
"Yes, I don't need to explain anything to me, I have 100 thousand miles on my speedometer," you can often hear such a phrase among the arguing cars. But the wording of thought is completely incorrect. If you analyze the speedometer and odometer, the difference in devices is obvious. It is an odometer that shows the mileage of the machine, the speedometer determines the speed of movement.
Deep in history
The most ancient odometer is mentioned in the first century. Greek Mathematics Geron became the parent of this invention. The device was in the form of a regular trolley, the wheels in which are selected with a special diameter. The wheels rotated exactly 400 times in 1598 meters (milliating). Got the simplest mechanism in motion. The mileage indicator served small stones that fell into the tray. To calculate the distance traveled, it was necessary to count the amount of stones dropped. Since then, people stepped far ahead in their inventions, but the idea itself was ideal.
Speedometer and odometer, the difference between which is not only indicated, have different dates of the invention. The speedometer invented a little over a hundred years ago. For the first time, such a device was installed on the OldSmobile car in 1901. For ten years, the speedometer was installed only as additional option And they considered him a wonder. Already later, at the factories began to install it as a mandatory device. In 1916, the speedometer has undergone improvements that Nicolas Tesla introduced. To this day, he reached almost in the same state, not counting some modern additions.
What is odometer? Device and purpose
So, every motorist should know what the speedometer and odometer are needed. The difference between these devices, of course exists. Consider first the odometer. What role does he play on the toolbar? Odometer is a mechanism that is designed to measure the number of revolutions of the wheel during the movement of the vehicle. In other words, this is a node that gives us the opportunity to find out the way passed by a car in kilometers. The odometer readings can be considered from a special device on the machine panel. Odometer shows both daily and common mileage. Two these scales are often located on the speedometer itself.
The design of the odometer is simple, includes the following components:
- The counter itself showing the number of revolutions of the wheel of your vehicle.
- The controller that fixes turns and is directly related to the meter itself.
- The indicator derived to the speedometer. Demonstrates a car traveled in kilometers.
Principle of action of odometer
Many newcomers and car enthusiasts often hear the terms "speedometer" and "odometer". The difference between these devices is not known to everyone. What is a odometer, we figured out, and now about the principle of action of the device, as it functions. Odometer is an electronic or mechanical devicewhich allows accuracy to determine the number of revolutions that is done by the wheel. Such data enable the driver to accurately determine how many kilometers his car passed for the entire service life and not only. You can also find out how much the car drove for one time interval. Data is displayed in the numerical value on the odometer indicator in kilometers.
In this, there is the essence of the work of the odometer - the vehicle wheel for each kilometer of the path passed is a strictly defined number of kilometers. This indicator is always the same. Knowing how many revolutions are done by the wheel, the counter calculates the path in kilometers.
If the driver has the need to determine the distance from point A to the point in, then it can always reset the counter. Thanks to this action, it is also easy to notice fuel consumption for a certain path. Naturally, with a non-working odometer, such an operation is simply impossible.
Types of odometers
Considering the odometer and the speedometer (there is a difference between them in the structure), we will define the types of odometers. There are three main types:
- Mechanical. Most old type, His progenitor was invented by ancient heron. If you need to wind such a odometer, it can be done by any twist. With the help of a digital meter, the rotation of the wheel of the mechanical component takes place. Under the influence of mechanical forces, the counter reads turns and converts them into a kilometer. The minus of such meters is that when a certain figure is reached, an automatic reset of readings occurs.
- Electronics. A more advanced odometer model. To correct such a meter, the use of CAN-multiple can already be applied. IN this case The wheel turnover is read by a counter using a mechanical connection, the information is subsequently converted into signals. Data in digital form is displayed on the dashboard.
- Digital odometers. Act on the basis of a microcontroller. The most modern device. All the necessary indicators in this case are read in digital format. To make a correction of such a odometer, the use of special equipment will be required. Digital odometer is a part of a vehicle on-board computer.
Odometer error
Everyone knows that any modern devices in their work have any inaccuracies. There are some standards that allow errors. In mechanical devices, for example, this indicator is allowed in 5%. If the vehicle is operated in any harsh conditions, then this figure can increase to 15%. In such cases there is a discount on wear of various parts, vehicle nodes (for example, slip). Formally, in this case, the wheels rotate (allegedly moves), but the path in kilometers does not increase.
A certain error in the work can be shown both odometer, and a speedometer (the difference between these devices is now clear). Also, various gaps are influenced on the instrument readings, weakening the cable, poor grip, weak springs. Electromechanical devices read signals that indicate a speed controller for a certain period of time. In these cases, the accuracy is lower, accuracy is higher. Cars with electromechanical devices, even very old, rarely give the error more than 5%. Digital devices The most accurate, mechanical connections are not involved here. If such devices have an error, then this is directly related to wheel wear.
What is a speedometer
Speedometer - a device that measures vehicle movements. The meter readings are displayed in km / h (kilometers per hour) or - in America - miles per hour. Speedometers are two types: mechanical (analog), digital. How does it act and what does the speedometer show? At the rear-wheel drive car, the speedometer controls the rotation of the secondary shaft at the gearbox, in this case the speed is calculated on it. Accordingly, speed readings will depend on the size of the tire, with rear bridgeas well as from your own error of the device. In front-wheel drive vehicles, the speed is measured using the left-wheel drive. A speedometer is added to the speedometer's error. We looked at the odometer and speedometer above (the difference, for which it serve, the principles of operation). We now find out the causes of the errors of the speedometer.
Why a speedometer is lying
If we consider the car speedometer, it is not difficult to guess why he is lying. Why shows the speed exceeded? First, the driver has less chances to break speed mode, get a fine. Secondly, if the speedometer indicated a smaller speed from the real, then, most likely, the drivers would not cease to sue automakers, proving their innocence in exceeding speed. Does the speedometer be sure to lie? The fact is that this device is more difficult to specify superely readings, because the speed depends on the wheel rotation, from its diameter, and this is a very unstable parameter.
The speedometer error at a speed of 60 km / h is very minimal, it is practically no. At a speed of 110 km / h, the accuracy can be 5-10 km / h. If the car develops speed up to 200 km / h, then the average error value can be up to 10%. We answered your question "What is odometer and speedometer". The difference is now understandable. Let's summarize. All of the above makes it possible to draw the following conclusions.
Odometer and speedometer: instrument differences
As already mentioned, not all motorists understand the difference between two different devices - odometer and speedometer. Some misleads the fact that the mileage meter is directly mounted in the speedometer itself. That is why many refer to this design to one instrument. What is this - odometer and speedometer? The difference between the functionality is obvious. It is simply unacceptable to confuse these devices. To be brief, then:
- The speedometer shows the speed of the vehicle.
- Odometer indicates the path traveled in kilometers.
Their functionality is not interrelated. The combination of these two scales is caused by only convenience for the driver's perception. However, modern withdraws this information on the display among the basic information.
Why drill mileage
"Speed \u200b\u200ba speedometer to reduce the mileage," is also an incorrect expression among motorists. We told why an odometer and a speedometer serves. The difference and photo of these devices indicate that the testimony is not a speedometer, namely the odometer, twisted to reduce the kilometer. Why do it? All justify these desires in different ways. Fault device, replacement of the entire panel, riding non-standard rubber. To be honest, then the reason is almost alone - everyone wants to "rejuvenate" their vehicle. Often this happens when selling a car. There are those who want, on the contrary, to increase the mileage. Often these are drivers of commercial vehicles that use cars for official purposes. After all, very often fuel consumption exceeds the permissible accounting of norms that do not take into account depreciation, the wear of the vehicle. To compensate for these costs, drivers and go to such a trick as an increase in the run.
