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