Under the Whyte notation for the classification of steam locomotives, 4-8-2 represents the wheel arrangement of four leading wheels, eight powered and coupled driving wheels and two trailing wheels. This type of steam locomotive is commonly known as the Mountain type, though the New York Central Railroad used the name Mohawk for their 4-8-2s.
NGR Hendrie D, an early example of a Mountain locomotive
NGR Class D
NGR Class B
CFB 11th Class 4-8-2 No. 401 at Lobito Station, Angola
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