{HEAD ~ The floating hinging point} is formed through two ball bearings , a fastening bolt , a coupling ring , a bearing house , {TAIL ~ an intermediate ring} and a self locking nut  
is formed through
{ HEAD ~ The floating hinging point } is formed through two ball bearings , a fastening bolt , a coupling ring , a bearing house , { TAIL ~ an intermediate ring } and a self locking nut
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH