A mine fan in which the air enters along the axis parallel to the shaft and is turned through a right angle by the blades and discharged radially. There are three main types with (1) backwardly inclined blades; (2) radial blades; and (3) forward curved blades. In (2) and (3) the blades are made of sheet steel, while in (1) the present tendency is to replace curved sheet-steel blades by blades of aerofoil cross section. The aerofoil bladed radial-flow fan has an efficiency of about 90%. Compare: axial-flow fan; mixed-flow fan.