The 2-2-2 locomotive "Pioneer" in service on the Cumberland Valley Railroad in the 1880s or 1890s.

(unknown, (Smithsonian negative 72-5999.), Public domain, via Wikimedia Commons)



Under the Whyte notation for the classification of steam locomotives, 2-2-2 represents the wheel arrangement of two leading wheels on one axle, two powered driving wheels on one axle, and two trailing wheels on one axle. The wheel arrangement both provided more stability and enabled a larger firebox than the earlier 0-2-2 and 2-2-0 types. This wheel arrangement is sometimes described as a Single, although this name could be used to describe any kind of locomotive with a single pair of driving wheels.


A diagram of the 2-2-2 Wheel Arrangement. Front of locomotive on left.

(Gwernol, Public domain, via Wikimedia Commons)


Equivalent classifications

Other equivalent classifications are:

  • UIC classification: 1A1 (also known as German classification and Italian classification)
  • French classification: 111
  • Turkish classification: 13
  • Swiss classification: 1/3



The 2-2-2 configuration appears to have been developed by Robert Stephenson & Company in 1834, as an enlargement of their 2-2-0 Planet configuration, offering more stability and a larger firebox. The new type became known as Stephenson's Patentee locomotive. Adler, the first successful locomotive to operate in Germany, was a Patentee supplied by Robert Stephenson & Company in component form in December, 1835 was one of the earliest examples. Other examples were exported to the Netherlands, Russia and Italy. By 1838 the 2-2-2 had become the standard passenger design by Robert Stephenson & Company.

Eighteen of the first nineteen locomotives ordered by Isambard Kingdom Brunel for the opening of the Great Western Railway in 1837/8 were of the 2-2-2 type. These included six 2-2-2 locomotives built by Charles Tayleur at his Vulcan Foundry. Also in 1837 the successful North Star broad gauge locomotive was delivered to the Great Western Railway by Stephenson, becoming the first of a class of twelve locomotives by 1841.


Preserved examples and replicas

  • CVRR 2-2-2, Pioneer, built by the Union Works, Boston Massachusetts, 1851. Held by the Smithsonian.