Front-End Auxiliary Drive (FEAD) or accessory drive systems in motor vehicles are used to drive auxiliary equipment, such as alternator, coolant pump, power steering pump or A/C compressor.
Accessories are driven by a poly V-belt or Serpentine belt, the tension of which is precisely adjusted to the required loads using a mechanical or hydraulic tensioning system. Guide pullies are used to create the required wrap angle around the front-end accessories. Poly V-belts are designed to perform at high loads transmitting the engine torque - up to 350 Nm is not unusual in modern cars, without slip from the crankshaft to all its accessories.