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