Toothed belt

[5][6][7] When correctly tensioned, these type of belts have no slippage, and are often used to transfer motion for indexing or timing purposes (hence their name).

Microlight aircraft driven by high-speed two-stroke engines such as the Rotax 532 use toothed belt reduction drives to allow the use of a quieter and more efficient slower-speed propeller.

Some amateur-built airplanes powered by automotive engines use cog belt reduction drive units.

Gilmer belts use trapezoidal teeth to engage matching grooves on toothed pulleys in order to maintain synchronicity between moving parts.

Originally this was rubber over a natural textile, but developments in material science have had a substantial effect in increasing the lifetime of these belts.

One failure mode is gradual wear to the tooth shape, which may eventually lead to slippage over rounded teeth.