A rotor for an electric motor or generator

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An external rotor for an electrical motor or generator (e.g. a wheel motor) has poles, each comprising a pair of rare earth permanent magnets 30 inclined towards each other in V formation. Soft ferromagnetic elements 32, 33 are arranged to retain the magnets, element 32 being mounted by its outer surface 35 to the inner rim of the rotor by means of adhesive or mechanical connectors, magnet surfaces 36 of each of the magnet pairs being adhesive mounted in V formation on the inclined inner surface of the element 32. Wedge shaped elements 33 are secured to the opposite face 37 of the magnets 30, and are arranged with respect to adjacent elements with an air gap 34 between respective end potions of the elements 33. Surface 38 of the element 33 forms the pole surface. The method of assembly may comprise magnetically holding the elements 33 to a former, securing the magnets 30 thereto, attaching the element 32 to the other faces of the magnets and subsequently mounting the circumferential potion of the rotor over element 32. The gap 34 may comprise a low reluctance material and the V assembly may be replaced by a single C shaped magnet.