Other equivalent classifications are: After early experience with the 0-2-2 configuration on the Liverpool and Manchester Railway, Robert Stephenson decided to build a locomotive with cylinders inside the frames, for which a 2-2-0 was preferable.

[1] The first such locomotive was Planet, built in 1830 and the company went on to build a further eighteen examples for the railway.

[2] After 1836 Edward Bury built sixty-nine bar frame 2-2-0 locomotives for the London and Birmingham Railway.

[4] Tom Thumb, the first American-built steam locomotive used on a common-carrier railroad, built by Peter Cooper in 1830 was a gear-driven 2-2-0, but the type was not perpetuated.

[7] Also Dugald Drummond of the London and South Western Railway introduced his C14 class 2-2-0T in 1906, for Auto trains, but this design was not successful and several of the locomotives were rebuilt to 0-4-0.