{HEAD ~ A drive circuit} selectively applies current to {TAIL ~ each electromagnet} to effect rotational force on the rotor poles 
selectively applies current to
{ HEAD ~ A drive circuit } selectively applies current to { TAIL ~ each electromagnet } to effect rotational force on the rotor poles
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH