Pulley

Pulley:
A rotating wheel on which a power transmission from a belt to an object takes place (such as on the serpentine belt, alternator, air conditioning pump, water pump and tensioner pulley) is called a pulley. The pulleys are often attached to the component with a screw connection. The serpentine belt has longitudinal ribs. The pulleys have internal grooves in which the ribs of the serpentine belt engage, so that the belt cannot slip off.

For more information, see the chapter serpentine belt.