As shown in FIG 21, {HEAD ~ the sections} of the outer and inner rings 152 and 153 in the seal system 151 are symmetrical with {TAIL ~ respect} to the axis of the second cylinder 115 relative to those of the outer and inner rings 156 and 157 in the seal system 155 
As shown in FIG 21 , { HEAD ~ the sections } of the outer and inner rings 152 and 153 in the seal system 151 are symmetrical with { TAIL ~ respect } to the axis of the second cylinder 115 relative to those of the outer and inner rings 156 and 157 in the seal system 155
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL REL REL 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 OTH OTH OTH OTH OTH