| 1/00 | Engines of impulse type, i.e. turbines with jets of high-velocity liquid impinging on bladed or like rotors, e.g. Pelton wheels; Parts or details peculiar thereto |
| 1/02 | Engines of impulse type, i.e. turbines with jets of high-velocity liquid impinging on bladed or like rotors, e.g. Pelton wheels; Parts or details peculiar thereto Buckets; Bucket-carrying rotors |
| 1/04 | Engines of impulse type, i.e. turbines with jets of high-velocity liquid impinging on bladed or like rotors, e.g. Pelton wheels; Parts or details peculiar thereto Nozzles (in general B05B); Nozzle-carrying members |
| 3/00 | Machines or engines of reaction type; Parts or details peculiar thereto |
| 3/02 | Machines or engines of reaction type; Parts or details peculiar thereto with radial flow at high-pressure side and axial flow at low-pressure side of rotors, e.g. Francis turbines |
| 3/04 | Machines or engines of reaction type; Parts or details peculiar thereto with substantially axial flow throughout rotors, e.g. propeller turbines |
| 3/06 | Machines or engines of reaction type; Parts or details peculiar thereto with substantially axial flow throughout rotors, e.g. propeller turbines with adjustable blades, e.g. Kaplan turbines |
| 3/08 | Machines or engines of reaction type; Parts or details peculiar thereto with pressure/velocity transformation exclusively in rotors |
| 3/10 | Machines or engines of reaction type; Parts or details peculiar thereto characterised by having means for functioning alternatively as pumps or turbines |
| 3/12 | Machines or engines of reaction type; Parts or details peculiar thereto Blades; Blade-carrying rotors |
| 3/14 | Machines or engines of reaction type; Parts or details peculiar thereto Blades; Blade-carrying rotors Rotors having adjustable blades |
| 3/16 | Machines or engines of reaction type; Parts or details peculiar thereto Stators |
| 3/18 | Machines or engines of reaction type; Parts or details peculiar thereto Stators Stator blades; Guide conduits or vanes, e.g. adjustable |
| 5/00 | Machines or engines characterised by non-bladed rotors, e.g. serrated, using friction |
| 7/00 | Water wheels |
| 9/00 | Endless-chain type machines or engines |
| 11/00 | Parts or details not provided for in, or of interest apart from, groups F03B 1/00-F03B 9/00 (controlling F03B 15/00) |
| 11/02 | Parts or details not provided for in, or of interest apart from, groups F03B 1/00-F03B 9/00 (controlling F03B 15/00) Casings |
| 11/04 | Parts or details not provided for in, or of interest apart from, groups F03B 1/00-F03B 9/00 (controlling F03B 15/00) for diminishing cavitation or vibration, e.g. balancing |
| 11/06 | Parts or details not provided for in, or of interest apart from, groups F03B 1/00-F03B 9/00 (controlling F03B 15/00) Bearing arrangements |