{TAIL ~ an extrusion screw} keyed on {HEAD ~ the driving shaft} to rotate in said sleeve element, 
{ TAIL ~ an extrusion screw } keyed on { HEAD ~ the driving shaft } to rotate in said sleeve element ,
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH