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