Subclass Subgroup Patent
F03B 13/18 12168967
  13/22 12168968
  13/26 12168969
F03D 3/062 12168970
    12168971
  9/257 12168974
  80/70 12168972
  80/85 12168973
F03G 7/0614 12168975
F03H 1/0025 12168976