a novel electric motor rotor structure , particularly desirable for use with brittle rare - earth - magnets , offers improved resistance to rattling and axial shifting . this is achieved by forming the rotor with an annular central yoke connecting to a plurality of pole shoes along the periphery of the rotor and defining a magnet - receiving recess or pocket 160 between each pole shoe and the central yoke . spaced circumferentially between adjacent magnets 38 are regions 146 of reduced magnetic conductivity , which include relatively thin metallic holding segments , which connect adjacent pole shoes to each other and to the central yoke . during manufacturing , tools are applied to upset or crimp the holding segments , and thereby form spring elements , to hold the magnets in stable positions and resist any tendency of the magnets to rattle or axially shift during motor operation . one obtains the same power level from a smaller , and therefore lighter , motor than was previously possible .