A motor drives a brush to sequentially connect {HEAD ~ the terminals} to the slip ring to energize the terminals in {TAIL ~ sequence} 
A motor drives a brush to sequentially connect { HEAD ~ the terminals } to the slip ring to energize the terminals in { TAIL ~ sequence }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL