Under the Whyte notation for the classification of steam locomotives, 0-6-4 represents the wheel arrangement of no leading wheels, six powered and coupled driving wheels on three axles, and four trailing wheels on two axles.

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.