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