An arrangement for the precleaning of air in an air duct upstream of a filter for the cleaning of air comprises a cyclone set (7) with cyclones (8) that together cover the cross-sectional area of the air duct and through which air is to pass on its way to the filter in order to separate particles from the air. A bend (10) is located immediately downstream of an outlet (9) from the set (7) that defines a change of direction of the said duct. A duct element (12) is arranged at the outlet (9) of the set (7) designed to define a section of channel (13) from the outlet through which the air must pass, and in its path away from the outlet towards a central axis (14) has converging walls (15).
