Manufacturer Sheffer Machine Co., Emlenton, PA
Owner: Chris Austin
Conversion usually involved reusing the donor steam engine’s frame, crankshaft, connecting rod, crosshead, and flywheel, and replacing the steam cylinder, piston, and valve linkage with new gas engine components. Fuel and ignition systems were added and the steam engine’s plain flat-belt pulley was normally replaced by a new clutch pulley.
Sheffer’s conversion required more blacksmithing and machining than most other makers’ designs. Using the four-stroke Otto cycle instead of a simpler two-stroke cycle necessitated adding timing gears, a power-operated exhaust valve with its attendant operating linkage, and a new heavier flywheel (note the unusual “doughnut cross-section” rim) to the conversion. Sheffer also incorporated a hit-miss speed governor and a ported cylinder, two more complications that most other makers thought unnecessary. His un-cooled, single-walled cylinder head and valve chests suggest limited pattern-making skills. Total engine production in the small shop was likely quite limited.
Using the four-stroke Otto cycle instead of a simpler two-stroke cycle necessitated adding timing gears, a power-operated exhaust valve with its attendant operating linkage, and a new heavier flywheel (note the unusual “doughnut cross-section” rim).
With a unique and unusually well-documented non-oilfield history, this particular converted engine spent its entire working life powering a small feed mill on a farm just north of Emlenton. The grandson of the original owner recalled accompanying his father and grandfather when they delivered, by horse and wagon, the used Struthers-Wells steam drilling engine to Sheffer’s machine shop for conversion into the gas engine it is today. Note that this engine retains its original steam engine plain pulley, likely because the expensive clutch pulley normally furnished as part of the conversion was not needed to start the gas engine while belted to the small feed mill.
It was placed into preservation in 2001.
Learn about this engine and 38 others in Coolspring: Discovering America’s Finest Antique Engine Museum, Vol. 2. Order your copy from our Gas Engine Magazine bookstore.