Serpentine belt

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Serpentine belt on belt tensioner.
Serpentine belt on belt tensioner.

A serpentine belt is a single, continuous belt used to drive multiple peripheral devices in an automotive engine, such as an alternator, power steering pump, water pump, A/C compressor, air pump, etc. The belt may also be guided by an idle pulley and/or belt tensioner. The serpentine belt was invented by Jim Vance while working for the Gates Rubber Company and first used by Ford Motor Company for the 1979 Mustang.

It is more efficient than the older multiple belt system. By using a single, wider belt instead of multiple, thinner belts, the belt may be put under increased tension without stretching. Higher tension reduces slip, which increases belt life and mechanical efficiency. Reduced slip can allow the use of lower-ratio pulleys; this reduces the load on the engine, increasing gas mileage and available power. Additionally, it is easier for the driver to know when the belt has broken, since this will cause the steering resistance to suddenly increase.[citation needed] With multiple belt systems, if a single belt breaks, such as the alternator belt, the driver may not realize that there is a problem until the engine fails completely.

A serpentine belt also is much easier to maintain and replace, since there is no need to remove multiple belts in order to replace one of them.

The drawback of this single belt is that if the belt breaks, the vehicle loses all peripheral devices. Some vehicles use two serpentine belts for their system, such as the 95–99 DOHC Nissan Maxima and many BMWs.