Abstract: An improved shrouded fan assembly (10, 10') is disclosed which forms a labyrinthian seal between a plurality of fan blades (20, 20') and an annular ring (16, 16') mounted to a non-rotating shroud (15, 15') without the use of a rotating annular shroud. The tip of at least one fan blade (20, 20') defines a slot (21, 21') adapted to receive the annular ring (16, 16') to form a labyrinthian seal therewith. The improvement increases fan efficiency by decreasing undesirable air flows in the shroud gap between the shroud (15, 15') and the tips of the fan blades (20, 20').

Abstract: A radiator cooling fan assembly is disclosed for use in trucks and other large vehicles. The heavy duty assembly includes a pair of hubs having radially extending arms with blades extending between aligned pairs of hub arms. The arms of one hub are substantially shorter than the arms of the other hub. In addition, the either hub may include either an enlarged aperture in its central portion or webbing between its arms or both.