The belt drive is a vital component of most modern machines. In it, a ring of a flexible material is wound around two or more shafts. As one shaft rotates, the belt moves, causing other shafts to rotate as well. This simple pulley device has long been a versatile and reliable means of transferring power.
In 100 B.C.E., while constructing Haterii's Tomb in Rome, workers used a treadmill-powered crane to lift heavy material. This was a historic moment for mechanics. In 1203, French innovators replaced the human workers who had been powering belt-driven technology with a team of donkeys.
Introducing animal power was far from the final stop for the belt drive. Water-powered mills used belt drives to harness water power, and Industrial Revolution-era factories employed belt drives, called line shafts, to transfer power throughout the factory.
Belt drives are also commonly used in engine designs. Belt drives can be found in most mechanical movers, from motorcycles to helicopters. Automobile engines usually contain belt-drive systems called V-belts and serpentine belts. These systems redirect and disperse engine power to accessories.
V-belts, named for their triangular "V" profile, are generally used to power the vehicle's air-conditioning compressor, alternator, power-steering pump, and water pump. They are frequently called fan belts.
A serpentine belt, an alternative to using a combination of several V-belts, has a longer life than the combined V-belts. A serpentine belt system uses a single, long belt to power the same number of accessories as numerous V-belts. Its name comes from its complex, snakelike path around multiple shafts. A spring-loaded pulley is used to keep the serpentine belt under optimum tension.
