The pivot shaft carries {HEAD ~ pivot arms} that in {TAIL ~ turn} pivotally support swing arms that can be selective locked to prevent pivotal movement between the pivot arms and unlocked so that as the pivot arms pivots the swing arms rotate relative to the pivot arms 
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The pivot shaft carries { HEAD ~ pivot arms } that in { TAIL ~ turn } pivotally support swing arms that can be selective locked to prevent pivotal movement between the pivot arms and unlocked so that as the pivot arms pivots the swing arms rotate relative to the pivot arms
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH