In stepping and synchronous inductor motors, rotor poles, which partially overlap stator poles at the usual annular working air gap, are successively coerced by magnetic fluxes emanating from stator windings disposed in line with the machine axis and between iron pieces. Magnetomotive vectors rotate...http://www.google.ca/patents/US3950663?utm_source=gb-gplus-sharePatent US3950663 - Inline motor iron and windings
