Each pair of {TAIL ~ bracing members} defines a guide for the displacement of the end supports of {HEAD ~ the support roller} for the lower belt 
Each pair of { TAIL ~ bracing members } defines a guide for the displacement of the end supports of { HEAD ~ the support roller } for the lower belt
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH