Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Hi Raphael,

The engine has a 3/4" (19 mm) bore and stroke and when in steam the boiler was at 20 psi. It does now tick over on air at about 2 psi.

The full size engines are often horizontal, the other size of the scotch yoke being connected to a pump. Also the full size ones tend to use a die block in the scotch yoke rather than just the crank pin. What is a bit unusual is the use of the yoke on the eccentric. Using a Scotch yoke rather than a connecting rod does make a very compact engine, good for use in a boat?

Take care Tony.