The angle α shows that the retainers 1 0 and 11 can be pivoted in {HEAD ~ the tension less state} to allow {TAIL ~ an increase} or reduction of the angle α 
to allow
The angle α shows that the retainers 1 0 and 11 can be pivoted in { HEAD ~ the tension less state } to allow { TAIL ~ an increase } or reduction of the angle α
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH