Abstract: Cotton harvester structure including centrally located, transversely mounted engine, rear mounted water and fuel tanks, and transversely centered conveyor fan having an upper, forwardly extending outlet located just below the level of the cab floor for improved weight distribution, air hose routing and air flow. The fan rotates about a transversely extending axis parallel to the engine crankshaft axis. The crankshaft and fan are connected by a belt and sheave assembly having an electric clutch mounted on a shaft assembly and located outside of the frame. The shaft assembly provides fan support, separates the fan inlet from the clutch, reduces lubrication requirements, and enhances accessibility.