A timing belt, timing chain, or cam belt is part of an internal combustion engine that controls the timing of the engine’s valves. Some engines use timing gears. The term “timing belt” is also used to describe any flat belt with integral teeth. Such belts are used for power transmission or interchange rotary and linear motions, where high loads or maintaining a specific drive ratio are important.

A common non-automotive application is linear positioning systems. Such belts have also been used in efforts to make a cleaner, lower-maintenance bicycle transmission but have never become popular in this application.

The camshaft opens and closes the valves in synchronicity with the movement of the pistons. Thus the name “timing belt.” A timing belt may also be called a Gilmer belt or a camshaft drive belt.

The timing belt is a large rubber band-looking belt notched in certain places to allow the crankshaft to turn the camshaft. The name timing belt comes from the fact that the belt is responsible for the synchronized movement of the camshaft and the pistons.

If the timing belt doesn’t keep the camshaft valves open and closed in parallel order with the camshaft, then the whole engine can fail. Also, if the timing belt breaks or slips off, it will cause the engine to stop working immediately or even damage the engine’s life.