How are Steam Locomotives Classed By Vol 1

Steam locomotives are classed by their wheel configurations. On steam locomotives the wheels that are driven by the steam engine are appropriately called drivers. Locomotives may have also have sets of non-powered pilot wheels before and/or after the drivers.

Steam locomotives are classified using a system called "Whyte Notation". In Whyte notation 2-8-4 means that the locomotive has two pilot wheels in front of eight driving wheels, followed by four more pilot wheels. Note that this is very different than the AAR Wheel Arrangement Notation used in classifying diesel and electric locomotives.

Wheel arrangements not listed were mostly less common types and their class names were usually alphanumeric codes which could vary from railroad to railroad. That is, if they were even used by more than one railroad.

On the Union Pacific, among other railroads, 4-8-4 locomotives were the "Northern" class. Railroads in the southern states wouldn't call a locomotive on their roster a "Northern". This resulted in many names for 4-8-4 locomotives. 4-8-4 class names are found in their own section.

Single Axle Lead Pilot Truck Classes

• 2-2-2 (8ft Drivers): Great Western
• 2-2-2 (7ft Drivers): Star or Firefly
• 2-4-0: Hawthorn or Victoria
• 2-4-2: Columbia
• 2-6-0: Mogul
• 2-6-2: Prairie
• 2-8-0: Consolidation
• 2-8-2: Mikado or Calument (MacArthur after Pearl Harbor)
• 2-8-4: Berkshire (Kanawha on the Chesapeake and Ohio Railroad)
• 2-10-0: Decapod
• 2-10-2: Santa Fe
• 2-12-0: Centiped