4-2-2

Under the Whyte notation for the classification of steam locomotives, a 4-2-2 locomotive has four leading wheels, two driving wheels and two trailing wheels.

Other equivalent classifications are:

UIC classification: 2A1 (also known as German classification and Italian classification)

French classification: 211

Turkish classification: 14

Swiss classification: 1/4

Like other steam locomotive types with single pairs of driving wheels, they were also known as singles.

Examples from the UK

* The Iron Duke class of Great Western Railway, built by Daniel Gooch. This broad gauge express locomotives were first built in 1847 and had an 8 ft diameter leading wheel size.
* The later examples of the GWR 3031 Class by William Dean, 1893-1899, built for standard gauge. No 3065 "Duke of Connaught" made a record-breaking run with the "Ocean Mail" express train on 9 May 1904, covering the distance from Plymouth to Paddington in 227 minutes.
* The GNR Stirling 4-2-2 of the Great Northern Railway, which ran an average speed of more than 60 mph during the race to the north, built first in 1870. They were called "eight-footer" because of the big driving wheel, that was more than 8 ft. in diameter.
* The Midland Railway's 115 class "Spinners". One, No. 673, survives at the National Railway Museum, York.
*A further notable UK class 4-2-2 is the GER Class P43, which was an early oil-burning engine, developed by the pioneer of oil-boilers, James Holden

Examples from Germany

* The first steam locomotive made by Borsig, Berlin, the "Borsig" No 1, was an 4-2-2, built 1841.