Belts are mechanical elements used for power transmission without phase shift. They are loops of flexible materials used to mechanically connect several rotating shafts, most often parallel. Belts can be used as a transmission element, to efficiently transmit power or movement.

One of the best-known applications for belts in the automotive industry, Cars having a ribbed belt to synchronize the movements of the main engine components (valve, pistons) during the various operating phases. A ribbed belt drives a number of peripheral components: alternator, power steering pump, water pump, etc. For the transport industry, we could also mention bicycles and motorcycles. Belts are also used in a wide range of industrial applications requiring motion or power transmission, particularly in conveyors.