Rotary lawn mowers

A lawn mower consists of a generally dome-shaped housing (12) surrounding an air impeller (17) and a rotary cutter (18), the impeller and the cutter being driven by a motor (10) supported above a central opening (20) in the roof (11) of the housing (12) such that rotation of the impeller induces a flow of air into the housing through the central opening. The motor (10) is surrounded by a protective shroud (13, 14, 15) which includes at least one air intake located such that air is initially drawn into the shroud (13, 14, 15) at a level or levels above that of the central opening (20) in the roof (11) of the housing (12) and is then drawn downwardly and inwardly such that it is moving in a direction substantially parallel to the axis of rotation of the impeller (17) before passing through the central opening (20).