Stationary engine

A stationary engine is an engine whose framework does not move. They are used to drive immobile equipment, such as pumps, generators, mills or factory machinery, or cable cars. The term usually refers to large immobile reciprocating engines, principally stationary steam engines and, to some extent, stationary internal combustion engines. Other large immobile power sources, such as steam turbines, gas turbines, and large electric motors, are categorized separately.

Stationary engines were once widespread in the era when each factory or mill generated its own power, and power transmission was mechanical (via line shafts, belts, gear trains, and clutches). Applications for stationary engines have declined since electrification has become widespread; most industrial uses today draw electricity from an electrical grid and distribute it to various individual electric motors instead.

Engines that operate in one place, but can be moved to another place for later operation, are called portable engines. Although stationary engines and portable engines are both "stationary" (not moving) while running, preferred usage (for clarity's sake) reserves the term "stationary engine" to the permanently immobile type, and "portable engine" to the mobile type.