4-4-0, in the Whyte notation, denotes a steam locomotive with a wheel arrangement of four leading wheels on two axles, four powered and coupled driving wheels on two axles, and no trailing wheels.
1856 relief sculpture of a 4-4-0 commissioned by the Norris Locomotive Works, depicting an early model prior to the adoption of the covered cab
Remains of a 4-4-0 locomotive of the Richmond & Petersburg Railroad, Richmond Virginia 1865
South Australian Railways S class No. 151, at Murray Bridge in March 1951
Finnish Class A4 locomotive of 1872
The Whyte notation is a classification method for steam locomotives, and some internal combustion locomotives and electric locomotives, by wheel arrangement. It was devised by Frederick Methvan Whyte, and came into use in the early twentieth century following a December 1900 editorial in American Engineer and Railroad Journal.
Whyte notation from a handbook for railroad industry workers published in 1906