This is a model of a “fore and aft” type compound steam engine. It is the kind of engine that had marine applications in powering tug boats, trawlers, and similar craft. A compound steam engine has two cylinders of different sizes. The smaller is the high pressure (HP) cylinder into which high pressure steam is introduced from the boiler. After expansion, its pressure reduces and its passed through the receiver to the low pressure (LP) cylinder. There it undergoes further expansion and is finally expelled through the exhaust pipes.
This engine also includes a fully working Stephenson link motion for reversing and controlling the point of cutoff for both cylinders. Detailed plans for this engine can be found in the first volume of The Shop Wisdom of Rudy Kouhoupt. Rudy’s original construction series on building this fore and aft compound ran in Live Steam magazine, in the issues from March through November 1988. The engine can be seen running in the video below.
