{HEAD ~ A pair} of {TAIL ~ elongated connector pipes} each having one end portion connected to the support structure for movement along the track 
of
{ HEAD ~ A pair } of { TAIL ~ elongated connector pipes } each having one end portion connected to the support structure for movement along the track
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH