Steam Locomotive Classification

Steam locomotives are classified by wheel arrangement. In the table below, the first number represents the number of wheels in the unpowered pilot truck used to guide the locomotive into turns and through switches. The last number represents the number of wheels in the usually unpowered trailer truck used to support the weight of large fireboxes. The middle numbers represent the number of drivers in a set coupled by drive rods.

This list contains only the more familiar locomotive wheel arrangements and names associated with them. Other wheel arrangements and variations exist(ed) and names varied with road and locale.

Yard and Industrial Switchers

Freight Locomotives
2-6-0    Mogul
2-8-0    Consolidation
2-10-0  Decapod
2-6-2    Paririe
2-8-2    Mikado
2-8-4    Berkshire
2-10-2  Santa Fe
2-10-4  Texas
2-6-6-6 Allegheny
2-8-8-2 Chesapeake
4-6-6-4 Challenger
4-8-8-4 Big Boy

Fast Freight and Passenger Locomotives
4-4-0    American
4-6-0    Ten-Wheeler
4-8-2    Mountain
4-8-4    Northern

Passenger Locomotives
4-4-2    Atlantic
4-6-2    Pacific
4-6-4    Hudson
4-4-4-4 Duplex

For a more detailed  listing of steam locomotive classes see American Steam Locomotive Wheel Arrangements at


Last updated: 11/27/10