This is a simple form of the early type of trunk or atmospheric engine. Steam is admitted in bottom part of cylinder A through part B causing piston to rise. At end of up stroke a jet of cold water is thrown into cylinder A through D, cooling steam and causing vacuum to draw piston down. The inertia stored in heavy, fly wheel on shaft during up stroke of piston, causes crank C to travel over center for down stroke. It is now obsolete but was generally used before the introduction of the slide valve engine (See No. 154).
[Virginia Downward & William M. Clark, 1930]

[Editor’s Note: The piston and crank engine uses a slider-crank mechanism that can be found in the Cornell Reuleaux Models C-1, C-4, D-1. FCM]

Francis Moon 2005-00-00