{HEAD ~ a hydraulic motor} operatively connected to {TAIL ~ each} of said first and second screw conveyor members; and 
{ HEAD ~ a hydraulic motor } operatively connected to { TAIL ~ each } of said first and second screw conveyor members ; and
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH