Contoured stationary plows are included at {HEAD ~ a downstream end} of {TAIL ~ the contiguous belt spans} to assist in turning the envelopes over 
Contoured stationary plows are included at { HEAD ~ a downstream end } of { TAIL ~ the contiguous belt spans } to assist in turning the envelopes over
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH