Corliss Steam Engine

A Corliss steam engine (or Corliss engine) is a steam engine, fitted with rotary valves and with variable valve timing patented in 1849, invented by and named after the American engineer George Henry Corliss in Providence, Rhode Island.

Engines fitted with Corliss valve gear offered the best thermal efficiency of any type of stationary steam engine until the refinement of the uniflow steam engine and steam turbine in the 20th century. Corliss engines were generally about 30 percent more fuel efficient than conventional steam engines with fixed cutoff. This increased efficiency made steam power more economical than water power, allowing industrial development away from millponds.

Corliss engines were typically used as stationary engines to provide mechanical power to line shafting in factories and mills and to drive dynamos to generate electricity. Many were quite large, standing several stories tall, and developing several hundred horsepower, albeit at low speed, turning massive flywheels weighing several tons at about 100 revolutions per minute. Some of these engines had unique roles as mechanical legacy systems and because of their relatively high efficiency and low maintenance requirements, some remain in service in early 21st century (see, for example, the engines at the Hook Norton Brewery and the Distillerie Dillon in the list of operational engines).