What drives the fan in a typical engine cooling system?

In a typical engine cooling system, the fan is primarily driven by the crankshaft. The crankshaft is a fundamental component of the engine that converts linear motion from the pistons into rotational motion. This rotational motion is utilized to drive several accessories, including the cooling fan.

The fan is usually attached to the front of the engine and is powered by a belt connected to the crankshaft. As the engine runs and the crankshaft rotates, the fan spins to draw air through the radiator, enhancing the cooling process of the engine coolant. This airflow is crucial for maintaining optimal engine temperature and preventing overheating.

The other options, while important components of engine operation, do not directly drive the fan in the engine cooling system. An electric motor, for example, is sometimes used in some vehicles to drive the fan, but in traditional cooling systems, the crankshaft is the primary means of fan operation. The water pump is responsible for circulating the coolant, and the alternator generates electrical power for the vehicle's systems, including possibly an electric fan, but it doesn't directly drive the cooling fan in conventional setups.