DIFF Subgroup
F16J 9/064 Full Title
Piston-rings , seats therefor; Ring sealings of similar construction (other sealings between pistons and cylinders F16J3/06, F16J15/16 ; tools for mounting or removing piston-rings or the like B25B; piston sealing arrangements on brake master cylinders B60T11/236 ) > using separate springs expanding the rings; Springs therefor
Of 2 combined children, 0 exist in both systems.
2 codes are CPC-only extensions.