{HEAD ~ A tractor supported and driven tree cutting apparatus} which causes {TAIL ~ linear movement} of a rotary cutter for cutting a tree trunk from the side portions thereof 
causes
{ HEAD ~ A tractor supported and driven tree cutting apparatus } which causes { TAIL ~ linear movement } of a rotary cutter for cutting a tree trunk from the side portions thereof
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH