Abstract: A lawnmower comprises a generally dome-shaped plenum chamber for supporting a motor or engine, a cutter and an air-impeller mounted for rotation within the said chamber, an air intake positioned centrally in the roof of said chamber above said impeller such that, in use, the impeller produces a cushion of air in the chamber bounded by a vortiginous air curtain, a peripheral flange extending outwardly from the bottom edge of said chamber in a direction substantially parallel to the ground, and means associated with said flange for partially trapping the turbulent air escaping from the said chamber beneath said flange whereby the rate of air loss from the said cushion is substantially reduced.