As shown in FIG 20, the section of the inner ring 153 is shaped like a fallen L and {HEAD ~ the section} of {TAIL ~ the outer ring} 152 is a rectangle seated on the L shaped section of the inner ring 153 
of
As shown in FIG 20 , the section of the inner ring 153 is shaped like a fallen L and { HEAD ~ the section } of { TAIL ~ the outer ring } 152 is a rectangle seated on the L shaped section of the inner ring 153
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 REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH