The odometer is one of the important components in your vehicle. For many reasons like while purchasing or buying a vehicle, for applying insurance, warranty etc. affect on the odometer reading. There are basically two types of odometers. Those are mechanical and computerized or digital odometers. The mechanical odometer has a gear train with gear ratio. For one-mile register, the input shaft has to spin 1690 times. These are replaced with digital odometers. Digital odometers are cost less and having more features.
- Mechanical Odometers: A tightly wound spring flexible cable turns the mechanical odometer. In the rubber housing protective metal tube, the cable spins inside. The output shaft of the transmission turns the cable on a car. To achieve the 1690: 1 gear reduction, the mechanical odometer uses a three worm gears series. The input shaft drives first worm. The first worm drives a gear. Only one tooth of the gear turns for each full revolution of worm. This gear turns another worm, the worm turns another gear, again it turns the last worm and finally last gear. The last gear is hooked up with tenth of a mile indicator. These types of mechanical odometers are rewindable. The odometer can go backwards when your car going in reverse order. It is just because of a gear train. When an odometer’s cable is hook to a drill and run backwards the odometer miles will automatically rewind. Therefore, there is a great chance to do the fraud. As well, it is even difficult to find the odometer fraud.
- Computerized Odometers: The computerized odometers are also called as digital odometers. If you check the recent bikes, you will find the bicycle computers instead of speedometers or cable driven odometers. In the bicycle computers, a magnet is attached to a wheel and a pickup attached to frame. Based on the magnet voltages, pickup calculate the distance traveled. Many modern cars are using a system as like this. A toothed wheel is using on a wheel instead of a magnetic pickup. The toothed wheel is mounted to the output of a magnetic sensor and the transmission. It counts the pulses of each tooth of wheel. Some cars are using a slotted wheel and an optical pickup like as computer mouse. The distance in these odometers is transmitted through a signal wire communication bus from ECU (engine control unit) to the dashboard. With many different devices connected to it, the car is like a LAN (local area network). The devices that may connect to the computer network in the car are transmission control module, body control module (operates lights, interior etc.), air bag control module, ABS (anti-lock braking system), radio, power window controls, dashboard, climate control system and the ECU.
Because of low cost, more accuracy, and lesser scope to fraud, Digital odometers are using instead of traditional mechanical odometers.