Coolspring Spotlight: Circa-1898 15 hp Evans-Gibbs & Sterrett Half-Breed

This 15 hp Evans-Gibbs & Sterrett featured a box bed design and had crankshaft and near-side flywheel that are original Gibbs & Sterrett pieces.

| December/January 2016

Circa-1898 15 hp Evans-Gibbs & Sterrett half-breed
Manufacturer: Evans Mfg. Co., Butler, PA; Gibbs & Sterrett, Corry, PA
Serial no.: 146
Horsepower: 15 hp
Bore & stroke: 9in x 12in
Ignition: Hot tube
Governing: Throttle governed
Owner: Paul Harvey

This converted steam drilling engine demonstrates another variation of oil field ingenuity where an internal combustion cylinder replaced the original steam cylinder on an oil field steam engine that was originally used to pump an oil well.

The frame

The engine dates to 1885 and was made by Gibbs & Sterrett in Corry, Pennsylvania. “You can tell this was a fairly old drilling engine because of its box bed design where the frame of the engine is basically box shaped, flat on the top and the various components including the cylinder, the crosshead support and the two main bearing blocks are bolted to the flat surface rather than cast in with the base when it was manufactured,” says Coolspring’s Clark Colby. The connecting rod, crankshaft and near-side flywheel are all original Gibbs & Sterrett pieces.

The cylinder

The conversion cylinder, made by the Evans Mfg. Co. of Butler, Pennsylvania, is of 4-cycle design, which is unusual as most of the converted engines were 2-cycle.

Evans made gas engines from about 1900 to as late as 1930 or 1940. “This cylinder design represents a fairly early version in that it has a boss mounted at a 45-degree angle on the cylinder casting that we believe was originally intended to hold a piston-tripped igniter,” says Clark. “That igniter seems never to have been commercialized by Evans.”


In this case, the conversion included adding an Evans flywheel on the offside that took an Evans clutch, which is not presently installed on this engine. “You needed to add a clutch when you did the conversion because unlike the steam engine, the gas engine would not start under load,” says Clark.