Circa-1883 5 MP Sombart

Coolspring Spotlight: Bisschop-type Sombart gas engine

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The circa-1883 5 MP Sombart features a crankshaft that is offset from the cylinder, as well as an ignition flame jet. The engine operated on the non-compression 2-stroke cycle invented by Jean Joseph Étienne Lenoir, who manufactured some of world’s first successful gas engines around 1860.

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Made by Sombart Mfg. Co., Hartford, CT
Year Circa-1883 
Horsepower 5 manpower
Bore 7-1/2-inch
Stroke 17-1/2-inch
Governing Hand-cock
Ignition Flame

The Sombart gas engine, manufactured in Hartford, Conn., 1882-1884, is commonly classified as a Bisschop-type engine. “It was an early attempt by an early engine manufacturer to get around Otto’s 4-cycle patent,” Wayne Grenning says.

The engine construction is unique, with the crankshaft offset from the cylinder axis.  The piston is guided with a tall, lubricated, light crosshead. The offset flywheel momentum served no typical balancing purpose, but assisted flywheel momentum by gravity on the exhaust down stroke.

Fuel consumption was excessive compared to the Otto cycle, but was not an issue with the lower powers, which ranged from 1 manpower (1/12 horsepower) to 5, the rating cast in this engine’s base.

Read more about this engine and 38 others in the new book, “Coolspring,” published by Gas Engine Magazine. It is available now, click here.