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