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