An odometer measures and displays the distance travelled by a vehicle by sensing the rotations of a wheel. Odometer consists of a gear assembly and bunch of rings. A cable called the driver cable is connected from the wheel to the gear assembly. When the wheel rotates the driver cable also rotates with the wheels that transfer the motion of wheel to the gear assembly which sets the gears in connected motion.
The gear assembly is made up of four gears in contact with each other. The image clearly shows position of each gear. On removing the gears we can clearly see the odometer as shown below.
The first ring of odometer is in contact with gear 4 which sets it in motion. To understand how the digits are moved in odometer assembly we need to have a clear picture of their design.
Let’s separate these rings and see how each ring is connected to other.
The odometer assembly is made up of six rings. Every ring is connected with the adjacent ring using the same arrangements. To avoid any confusion let us understand the mechanism between the first two rings. The image shows the exact arrangement as to how the rings are interconnected. If we look carefully a white structure is visible. It is a small gear which is covered with the plastic plate. The plastic plate has a small cut through which we can see some of the teeth’s of the white gear coming out.