A fan unit for a combine harvester cleaning unit having at least two fan wheels, each fan wheel being enveloped by a fan wheel housing having at least one inlet segment and at least one outlet segment extending tangentially from the fan wheel housing, each outlet segment being connected to a common channel section and each vertical side wall of an outlet segment adjacent another outlet segment is inclined toward the vertical side wall of the adjacent outlet segment. This construction has as an advantage that it allows for improved flow characteristics of the air exiting the outlet thereby permitting better separation of MOG and grain in the sieves of the cleaning unit of which the fan unit is a part.
