Steam Locomotive Classes

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 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 trailing wheels. Note that this is...MORE very different than the AAR Wheel Arrangement Notation used in classifying diesel and electric locomotives.

  • 01 of 07

    Steam Locomotive Class Names

    NKP 765
    Nickel Plate Road 765 charges east on her way to another employee excursion venue. ©2012 Ryan C Kunkle, licensed to About.com, Inc.

    Classes were frequently given names; a 2-8-4 locomotive was known as a "Berkshire". The Polar Express was pulled by a Berkshire locomotive.

    Below are lists of steam locomotive class names, listed by their wheel configurations. If you've heard a locomotive referred to as a "Pacific" or a "Mogul" and want to know its wheel configuration, you can find it by using your browser's "Find in This Page" option, usually located in the Edit menu.

  • 02 of 07

    Notes

    NW J
    Norfolk and Western's J class represented one of the most refined locomotives of any type. No. 611 entertained thousands in the 1980s in excursions. ©2013 Ryan C Kunkle, licensed to About.com, Inc.
    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...MORE their own section.
  • 03 of 07

    Single Axle Lead Pilot Truck Classes

    Pacific
    Reading and Northern Pacific No. 425 leads an excursion through the beautiful Lehigh Gorge. Although not a true USRA light Pacific, the locomotive is similar in design. ©2013 Ryan C Kunkle, licensed to About.com, Inc.
    • 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
    • 2-10-4: Texas
    • 2-12-0: Centipede
  • 04 of 07

    Two Axle Lead Pilot Truck Classes

    York 4-4-0
    The "York" recalls the era when President Lincoln rode the Northern Central's rails to deliver "a little speech" in Gettysburg. The beautiful locomotive was completed in 2013 - 150 years later. ©2013 Ryan C Kunkle, licensed to About.com, Inc.
    • 4-2-0: Jervis
    • 4-2-2: Iron Duke/Rover
    • 4-4-0: American
    • 4-4-2: Atlantic
    • 4-6-0: Ten Wheel
    • 4-6-2: Pacific or St. Paul
    • 4-6-4: Hudson or Baltic
    • 4-8-0: Twelve Wheel
    • 4-8-2: Mountain
    • 4-8-4: *see 4-8-4 Locomotive Class Names (below)
    • 4-10-0: Mastodon
    • 4-10-2: Southern Pacific (named for the primary railroad to use them)
    • 4-12-2: Union Pacific (named for the only railroad to use them)
    Continue to 5 of 7 below.
  • 05 of 07

    4-8-4 Locomotive Class Names

    N&W 611
    Norfolk and Western 611. ©2015 Ryan C Kunkle, licensed to About.com, Inc.
    As railroads in southern states wouldn't use the name "Northern", many alternative names for the 4-8-4 were coined:
    • Northern: Union Pacific and various other railroads
    • Big Apple: Central of Georgia RR
    • Confederation: Canadian National Railway
    • Confederation: Grand Trunk Western RR
    • Dixie: Nashville, Chattanooga & St. Louis Railway
    • General, Governor, or Statesman: Richmond, Fredericksburg & Potomac RR
    • Greenbrier: Chesapeake & Ohio Railway
    • GS, Golden State or General Service:...MORE Southern Pacific RR
    • Niagara: New York Central RR
    • Niagara:Ferrocarriles Nacionales de Mexico
    • Pocono: Delaware, Lackawanna & Western RR
    • Potomac: Western Maryland Railway
    • Western: Denver & Rio Grande Western RR
    • Wyoming: Lehigh Valley RR
  • 06 of 07

    Duplex Steam Locomotives

    Duplex locomotives had two engines and two sets of drivers on a single rigid frame.
    • 6-4-4-6: Pennsylvania (the only one made was owned by PRR)
  • 07 of 07

    Articulated Steam Locomotives

    2-4-4-2
    A G Gauge 2-4-4-2 Mallet shows a typical look for these lighter articulateds used on many logging railroads. ©2014 Ryan C Kunkle, licensed to About.com, Inc.

    Articulated locomotives had multiple engines and sets of drivers that could move independently of each other.

    • 2-6-6-6: Allegheny (C&O) or Blue Ridge (Virginian Railway)
    • 2-8-8-0: Bull Moose
    • 2-8-8-2: Y Class (Norfolk & Western)
    • 2-8-8-4: Yellowstone
    • 2-10-10-2: Virginian
    • 4-6-6-4: Challenger
    • 4-8-8-4: Big Boy
    • 2-8-8-8-0: Triplex (1 made)
    • 2-8-8-8-2: Triplex (3 made)
    • 2-8-8-8-4: Triplex (1 made)

    Edited by Ryan Kunkle