A second base plate 51 is rotatably mounted on the first base plate 50 having {HEAD ~ a centrally disposed pin} 52 extending into {TAIL ~ an opening} 53 in the base plate 50 
extending into
A second base plate 51 is rotatably mounted on the first base plate 50 having { HEAD ~ a centrally disposed pin } 52 extending into { TAIL ~ an opening } 53 in the base plate 50
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH