Abstract: The invention relates to an axial fan comprising a boss and a number of blades evenly distributed and arranged to the boss, wherein the blades have an aerofoil profile, each blade is arranged to the boss with a strip, wherein each blade is hollow and the strip is at least partially inserted into the blade, and that at least one fastener runs from the surface of the blade through a corresponding opening in the strip to the opposite surface of the blade, wherein the corresponding opening in the strip is a slot, such that the pitch of the blade is adjustable, by rotation of the blade relative to the strip along the axial axis of the blade.

Abstract: The invention relates to an axial fan comprising a boss and a number of blades evenly distributed and arranged to the boss, wherein the blades have an aerofoil profile, each blade is arranged to the boss with a strip, wherein each blade is hollow and the strip is at least partially inserted into the blade, and that at least one fastener runs from the surface of the blade through a corresponding opening in the strip to the opposite surface of the blade, wherein the corresponding opening in the strip is a slot, such that the pitch of the blade is adjustable, by rotation of the blade relative to the strip along the axial axis of the blade.

Abstract: A rotor blade for a fan, said rotor blade comprising a first blade zone having an airfoil cross-section and a second blade zone having a cross-section of reduced thickness, wherein the average thickness of the second blade zone is less than 50% of the average thickness of the first blade zone.

Abstract: A blade for a fan is formed by rotomolding around a pre-positioned support member, part of which extends out of the mold, the support member being shaped, or being provided with one or more projections, which are partly embedded in the plastic material forming a skin of the fan blade. The fan blade is made hollow by this method, but is preferably filled either during molding or subsequently with a hard foam material. A hub is also provided for mounting any fan blades, but in particular those made by the method, in which a hub includes a body portion having a first radial face associated therewith, a plate having a second radial face parallel to the first radial face and spaced therefrom, and a plurality of circumferentially equally spaced depressions facing one another on the first and second radial faces to accommodate the fan blade support members, means being provided to secure the plate to the body portion effective to clamp the fan blade and support members firmly.