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