On the verge of summer vacation, it’s time to get the car ready and we must stop at certain factors that will be key. One of them is the speedometers , but I don’t know if you’ve noticed that it doesn’t show the real speed of the car. Why?
According to European regulations, the speed indicated by the car’s speedometer must not be less than the real speed , with a maximum margin of error on the real speed of 10% + 4 km / h.
But of course, this depends not only on EU regulations but also on other international ones. Car brands from other places like the Japanese ones adhere to the SAE J1226 standard which admits an error of 4%, both above and below the actual speed.
It is clear that speeding is an added problem in cars, because they generate many fines and it is also one of the main causes of car accidents in our country. Thus, for this and many other factors, it should be noted that manufacturers, as they do not want to have problems related to accidents or fines for speeding , ensure that we go slower than we think.
Thus and to give an example, if we have a speed of 100 km / h, the maximum error limit is 14 km / h, and the speed is from a minimum of 100 km / h to a maximum of 114 km / h.
How does the speedometer work?
Another reason why car speedometers do not indicate the real speed at which we are going or we think we are reaching is that this device measures the rotation of the secondary shaft of the gearbox or of the car wheel. Then extrapolate a speed using a mathematical formula.
Continuing with the vision of the manufacturers, they usually measure according to one of the wheels , but the diameter of these can be altered for various reasons, be they excesses or defects of pressure, etc. and the conclusion is that the speed ends is not correct.
Use a GPS or an app
To accurately measure speed we can do it with a GPS, or a smartphone app. A tip that many drivers use, regardless of the type of car and brand they have is from one country or another. Because that way you will know the speed at which you are going and not the one marked by the speedometers that you already know does not mark the real speed.
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