A rotating wheel where a power transmission from a belt to an object takes place (such as e.g. to the V-ribbed 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 V-ribbed belt has ribs The pulleys have internal notches into which the ribs of the V-ribbed belt hook, so that the belt cannot slide off.
For more information, see the chapter multi-belt.