On some engines equipped with a timing belt, which component may also be driven by the belt?

In some engines equipped with a timing belt, the water pump is often driven by the belt itself. This design is advantageous because it ensures that the water pump operates in sync with the engine's timing, enabling the coolant to circulate effectively while the engine is running. When the timing belt turns, it simultaneously turns the water pump, which helps maintain optimal operating temperatures for the engine by allowing the coolant to flow to and from the engine block and radiator.

In contrast, the other components listed typically have separate drives or are not linked directly to the timing belt. For instance, the oil pump generally operates independently of the timing belt in many engine designs, driven instead by the engine’s crankshaft through gears or a chain. Similarly, the generator and air compressor are usually belt-driven from the engine's crankshaft but not through the timing belt itself, allowing for simpler maintenance and replacement without jeopardizing the timing system.