Serpentine Belt - Definition

A serpentine belt is a single continuous belt used to drive multiple peripheral devices in an automotive engine, such as alternators, power steering pumps, coolant pumps, A/C compressors, etc.

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 stetching. Higher tension reduces slip, which increases belt life and mechanical efficiency. Reduced slip can allow the use of lower ratio pulleys, which reduces the load on the engine, increasing gas mileage and available power. An added benefit to a single belt is that should it break, the driver immediately knows there is a problem due to the sudden change in steering resistance. With multiple belt systems, if a single belt breaks, such as the alternator belt, the driver may not realize there is a problem until the engine quits running.

Serpentine belts are also much easier to maintain and change, since there is no need to remove multiple belts to replace a single broken or worn belt. Removal of belts can itself cause stress and premature wear.

The drawback of this single belt is that if the belt breaks the vehicle loses all peripheral devices.