{HEAD ~ Each roller assembly} 43 comprises {TAIL ~ an upper roller} 45 and a lower roller 46, with a power source 44 for rotating the upper rollers 45 
comprises
{ HEAD ~ Each roller assembly } 43 comprises { TAIL ~ an upper roller } 45 and a lower roller 46 , with a power source 44 for rotating the upper rollers 45
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH