Radial Steam Engines>
Radial steam engines have three or more cylinders arranged at an equal spacing on a circle around the crankshaft. The cylinders stay still while the crankshaft revolves; this may seem a crashingly obvious statement but there were such things as rotary engines, in which the crankshaft stayed still and the cylinder assembly revolved around it. These should not be confused with the other sort of rotary engine, in which some kind of a piston rotated in a fixed housing.
THE BROTHERHOOD RADIAL ENGINE
The Brotherhood engine was a popular and successful three-cylinder radial design that was adapted for various operating fluids. A large number were used as water engines, for driving hydraulic capstans in docks and so on, but they were also widely used as steam engines. Versions for steam use are shown here; it is notable that the steam versions show considerable design differences from the water-driven version.
Left: The Brotherhood Radial Engine: axial section
Left: The Brotherhood Radial Engine: longitudinal section
Above: The Brotherhood Radial Engine: alternative valvegear
Left: The Brotherhood Radial Engine: account of a test