The dynamo of your car is driven by the crankshaft. The flywheel is connected to the crankshaft. The rotational movement is transmitted to the water pump, alternator, steering pump and possibly the air conditioning pump via the V-belt , in modern cars this is often a multi-belt. The belt is kept tight by the tensioner pulley, and the guide pulley guides the belt in the right direction.
Freewheel pulley
To ensure that the belt does not slip or rattle due to the variable rotation speed of the crankshaft, a freewheel clutch or freewheel pulley is often attached to the dynamo. This freewheel clutch absorbs the variation in speed, so that the dynamo itself is not damaged by the tight and slack of the drive belt.