Look up “fan belt” in any modern automotive dictionary, and you’ll typically find a definition that reads, “An endless belt used to transmit power from a crankshaft-driven pulley to a pulley driving the fan, alternator, or other engine accessory. It is usually V-shaped in cross section with the point of the V fitting into a groove in the pulley”.

Even though cooling fans on most modern vehicles are driven by electric motors instead of actual belts, the term fan belt is still incorrectly used as a blanket expression to describe any single accessory belt that may be used to drive a water pump, alternator, power steering pump, or other items. Why?

In order to pull cooling air through a vehicle’s radiator, a cooling fan needs to be located at the front of the vehicle just behind the radiator. Traditional rear-wheel-drive vehicles with longitudinally-mounted engines had crankshaft pulleys right there at the front of the car, and they were convenient sources of power for cooling fans.

Since the fan belt tended to be the biggest and most noticeable one on the vehicle, the expression became universal for all other belts that looked similar – no matter what function they performed. Many original engine layouts also used that fan belt to spin water pump and alternator pulleys, and you may hear some people call this belt a “water pump belt” or “alternator belt” as well as a fan belt.

However, as vehicles with front-wheel-drive and sideways-mounted engines grew in popularity, the front of the engine was no longer at the front of the vehicle where the cooling fan was.

Engineers perfected electric fan motors, temperature sensors, and related computers to get the job done, and belt-driven fans were no longer necessary. Because cooling fans don’t always need to be running at steady cruising speeds, electric motors which can shut off proved more energy efficient than direct drive belts which are always connected. Since electric cooling fans are used even in modern vehicles with longitudinally-mounted engines, the term fan belt has become virtually obsolete. More fitting terms to use when searching for a replacement single belt of this kind would be accessory drive belt or V-belt.

Because drive belts are subject to constant rotation, load, and heat, they are constructed in a similar fashion as tires. An outer layer of rubber surrounds internal steel and cord reinforcements to minimize stretching and maximize strength when grip is needed under load.

This article comes from carid edit released