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