The odometer is a record of all the components of a car, not just the engine. When your odometer ceases to work, most people assume they must replace the unit, which can get quite expensive. The mileage is then displayed on the screen of the scan tool. For instance in California, vehicles that are 10 years old or older are not required to have mileage disclosed.
Begin typing your search term above and press enter to search. Press ESC to cancel. Skip to content Home Essay What causes the odometer to stop working?
Ben Davis February 4, Each full revolution of the worm only turns the gear one tooth. That gear turns another worm, which turns another gear, which turns the last worm and finally the last gear, which is hooked up to the tenth-of-a-mile indicator.
Each indicator has a row of pegs sticking out of one side, and a single set of two pegs on the other side. When the set of two pegs comes around to the white plastic gears, one of the teeth falls in between the pegs and turns with the indicator until the pegs pass. This gear also engages one of the pegs on the next bigger indicator, turning it a tenth of a revolution. You can now see why, when your odometer "rolls over" a large number of digits say from 19, to 20, miles , the "2" at the far left side of the display may not line up perfectly with the rest of the digits.
A tiny amount of gear lash in the white helper gears prevents perfect alignment of all the digits. Usually, the display will have to get to 21, miles before the digits line up well again. You can also see that mechanical odometers like this one are rewindable. When you run the car in reverse, the odometer actually can go backwards -- it's just a gear train. In the movie " Ferris Bueller's Day Off ," in the scene where they have the car up on blocks with the wheels spinning in reverse -- that should've worked!
In real life, the odometer would've turned back. Another trick is to hook the odometer's cable up to a drill and run it backwards to rewind the miles. While that does work on older mechanical odometers, it does not work on the new electronic ones, as we will see in the next section If you make a trip to the bike shop, you most likely won't find any cable-driven odometers or speedometers.
Instead, you will find bicycle computers. Bicycles with computers like these have a magnet attached to one of the wheels and a pickup attached to the frame. Once per revolution of the wheel, the magnet passes by the pickup, generating a voltage in the pickup. The computer counts these voltage spikes, or pulses, and uses them to calculate the distance traveled. If you have ever installed one of these bike computers, you know that you have to program them with the circumference of the wheel.
The circumference is the distance traveled when the wheel makes one full revolution. Each time the computer senses a pulse, it adds another wheel circumference to the total distance and updates the digital display. Many modern cars use a system like this, too. Instead of a magnetic pickup on a wheel, they use a toothed wheel mounted to the output of the transmission and a magnetic sensor that counts the pulses as each tooth of the wheel goes by.
When your odometer ceases to work, most people assume they must replace the unit, which can get quite expensive. However, you can repair an odometer fairly easily. The odometer stops working because the gear within the odometer has worn out. Table of Contents.
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