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