This rubber coupling connects the engine-driven fan to the cooling-system drive assembly. It transmits torque from the crankshaft pulley to the fan hub, maintaining proper airflow across the radiator core during operation. A failed coupling allows the fan to slip or seize, causing insufficient cooling airflow and elevated coolant temperatures under sustained load. The coupling is manufactured to the original geometry and material specification, which preserves the torsional stiffness the fan-drive system requires for consistent engagement. On installation, verify that the coupling is not twisted or preloaded before tightening the fasteners.