The auger flights are formed from {HEAD ~ a flange} that is helical around {TAIL ~ the central shaft} and the direction of rotation of the helix may reverse at a selected point on the tube 
is helical around
The auger flights are formed from { HEAD ~ a flange } that is helical around { TAIL ~ the central shaft } and the direction of rotation of the helix may reverse at a selected point on the tube
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL 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