Gerry's Beam Engine

[mklotz]

With that steam chest arrangement it looks as if there is no way to fine tune the position of the D-valve. At least I can't detect one.

In Elmer Verburg's design, the valve spindle is threaded. A slot in the D-valve restrains a nut through which the threaded spindle passes. The valve is free to float up and down on this nut so the steam pressure can hold it against the cylinder wall.

By turning the spindle through 180 degrees the position of the valve can be adjusted relative to the intake/exhaust ports by an amount equal to half the pitch on the spindle thread.

This fine tuning allows one to take out minor errors in the valve train and thus optimize the engine performance.

If you have problems getting the engine to run well, you might want to think about using an adjustable valving scheme.