0-8-4

An 0-8-4, in the Whyte notation for the classification of steam locomotives by wheel arrangement, is a locomotive with no leading wheels, eight driving wheels (4 axles) fixed in a rigid frame, and four trailing wheels (normally mounted in a trailing truck). An example of this class is the Great Central Railway's S1.

Other equivalent classifications are:

UIC classification: D2 (also known as German classification and Italian classification)

French classification: 042

Turkish classification: 46

Swiss classification: 4/6