The wheel arrangement for the Z21 class was
2-6-0. Under the
Whyte notation for the classification of steam locomotives, 2-6-0 represents the wheel arrangement of two leading wheels on one axle, usually in a leading truck, six powered and coupled driving wheels on three axles and no trailing wheels.[citation needed] This arrangement is commonly called a
Mogul.[5][citation needed]
^Preston, Ron G (1984). Tender into Tank. Sydney: New South Wales Rail Transport Museum. pp. 11–57.
ISBN0-909862-18-4.
^Grunbach, Alex (1989). A Compendium of New South Wales Steam Locomotives. Sydney: Australian Railway Historical Society, NSW Division. pp. 41–45.
ISBN0-909650-27-6.
^New South Wales Railways 1855-1955. Published by Department of Railways