This Twin Walking Beam steam engine model is my own design, but with a big tip of the hat to Elmer Verburg and Larry Dykstra for details and techniques. I got interested in model steam engines through my father-in-law who built quite a few after retirement in Pensacola. I inherited Bruce’s metal working lathe and tools and have put them to good use in the last few years. This is my third completed engine.
What intrigued me about beam engines is the linkage that converts rotary motion to straight-line motion. The linkage on the left side was invented by a Scotsman named James Watt in 1784. It allows doubling of the piston power over a conventional linkage, such as an oil well pump jack which can only pull, by allowing piston power strokes on both the up and down stroke. Watt’s “parallel linkage” does not generate the true straight-line motion required by the piston/cylinder but over a limited range it’s very close. This double acting linkage doubles the power of a steam engine and was a significant development in the evolution of the steam engine.
The linkage on the other side of the engine was invented in 1864 by two men working independently; a Frenchman named Charles Peaucellier and a Lithuanian, Yom Lipkin. This linkage is more complex to build but provides perfect rotary-to-straight-line motion.
I haven’t seen a twin beam application but I wanted to demonstrate both types of linkages so I came up with this design.