A Corliss steam engine is a steam engine, fitted with rotary valves and with variable valve timing patented in 1849, invented by and named after the US engineer George Henry Corliss of Providence, Rhode Island.
A Corliss steam engine – the valve gear is on the right of the cylinder block, on the left of the picture
"Gordon's improved Corliss valvegear", detailed view. The wrist-plate is the central plate from which rods radiate to each of the four valves.
Detail of a Corliss-type valve gear and cylinder cross section showing the path of high-pressure steam (in red) and low-pressure steam (in blue). With each stroke, the four valves alternate opening and closing, driving the piston back and forth
Valve gear typical of engines developed by Corliss competitors. The horizontal arrangement of the dashpots and the lack of a wrist plate avoided key claims in the Corliss patents.
A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a cylinder. This pushing force can be transformed, by a connecting rod and crank, into rotational force for work. The term "steam engine" is most commonly applied to reciprocating engines as just described, although some authorities have also referred to the steam turbine and devices such as Hero's aeolipile as "steam engines". The essential feature of steam engines is that they are external combustion engines, where the working fluid is separated from the combustion products. The ideal thermodynamic cycle used to analyze this process is called the Rankine cycle. In general usage, the term steam engine can refer to either complete steam plants, such as railway steam locomotives and portable engines, or may refer to the piston or turbine machinery alone, as in the beam engine and stationary steam engine.
A model of a beam engine featuring James Watt's parallel linkage for double action
A mill engine from Stott Park Bobbin Mill, Cumbria, England
A steam locomotive from East Germany. This class of engine was built in 1942–1950 and operated until 1988.
A steam ploughing engine by Kemna