| 1/00 | Reciprocating-piston liquid engines |
| 1/007 | Reciprocating-piston liquid engines with single cylinder, double-acting piston |
| 1/013 | Reciprocating-piston liquid engines with single cylinder, single-acting piston |
| 1/02 | Reciprocating-piston liquid engines with multiple cylinders, characterised by the number or arrangement of cylinders (with movable cylinders F03C 1/22; of flexible-wall type F03C 7/00) |
| 1/03 | Reciprocating-piston liquid engines with multiple cylinders, characterised by the number or arrangement of cylinders (with movable cylinders F03C 1/22; of flexible-wall type F03C 7/00) with movement in two directions being obtained by two single-acting piston liquid engines, each acting in one direction |
| 1/04 | Reciprocating-piston liquid engines with multiple cylinders, characterised by the number or arrangement of cylinders (with movable cylinders F03C 1/22; of flexible-wall type F03C 7/00) with cylinders in star- or fan-arrangement |
| 1/047 | Reciprocating-piston liquid engines with multiple cylinders, characterised by the number or arrangement of cylinders (with movable cylinders F03C 1/22; of flexible-wall type F03C 7/00) with cylinders in star- or fan-arrangement the pistons co-operating with an actuated element at the outer ends of the cylinders |
| 1/053 | Reciprocating-piston liquid engines with multiple cylinders, characterised by the number or arrangement of cylinders (with movable cylinders F03C 1/22; of flexible-wall type F03C 7/00) with cylinders in star- or fan-arrangement the pistons co-operating with an actuated element at the inner ends of the cylinders |
| 1/06 | Reciprocating-piston liquid engines with multiple cylinders, characterised by the number or arrangement of cylinders (with movable cylinders F03C 1/22; of flexible-wall type F03C 7/00) with cylinder axes generally coaxial with, or parallel or inclined to, main shaft axis |
| 1/08 | Reciprocating-piston liquid engines Distributing valve-gear peculiar thereto (for multiple-cylinder engines F03C 1/34; for engines with positive displacement in general F01L) |
| 1/10 | Reciprocating-piston liquid engines Distributing valve-gear peculiar thereto (for multiple-cylinder engines F03C 1/34; for engines with positive displacement in general F01L) actuated by piston or piston-rod |
| 1/12 | Reciprocating-piston liquid engines Distributing valve-gear peculiar thereto (for multiple-cylinder engines F03C 1/34; for engines with positive displacement in general F01L) actuated by piston or piston-rod mechanically |
| 1/14 | Reciprocating-piston liquid engines Distributing valve-gear peculiar thereto (for multiple-cylinder engines F03C 1/34; for engines with positive displacement in general F01L) actuated by the driving liquid of the engine |
| 1/16 | Reciprocating-piston liquid engines Distributing valve-gear peculiar thereto (for multiple-cylinder engines F03C 1/34; for engines with positive displacement in general F01L) Speed controlling, equalising, or cushioning |
| 1/20 | Reciprocating-piston liquid engines Distributing valve-gear peculiar thereto (for multiple-cylinder engines F03C 1/34; for engines with positive displacement in general F01L) specially adapted for engines generating vibration only |
| 1/22 | Reciprocating-piston liquid engines with movable cylinders |
| 1/24 | Reciprocating-piston liquid engines with movable cylinders in which the liquid exclusively displaces one or more pistons reciprocating in rotary cylinders |
| 1/247 | Reciprocating-piston liquid engines with movable cylinders in which the liquid exclusively displaces one or more pistons reciprocating in rotary cylinders with cylinders in star- or fan-arrangement |
| 1/253 | Reciprocating-piston liquid engines with movable cylinders in which the liquid exclusively displaces one or more pistons reciprocating in rotary cylinders with cylinder axes generally coaxial with, or parallel to, main shaft axis |
| 1/26 | Reciprocating-piston liquid engines adapted for special use or combined with apparatus driven thereby (aspects predominantly concerning the driven apparatus, see the relevant classes for such apparatus) |