Under the

Whyte notation The Whyte notation is a classification method for steam locomotives, and some internal combustion locomotives and electric locomotives, by wheel arrangement. It was devised by Frederick Methvan Whyte, and came into use in the early twenti ...

for the classification of

steam locomotive A steam locomotive is a locomotive that provides the force to move itself and other vehicles by means of the expansion of steam. It is fuelled by burning combustible material (usually coal, Fuel oil, oil or, rarely, Wood fuel, wood) to heat ...

wheel arrangement In rail transport, a wheel arrangement or wheel configuration is a system of classifying the way in which wheels are distributed under a locomotive. Several notations exist to describe the wheel assemblies of a locomotive by type, position, and c ...

s, a 4-4-6-2 is a locomotive with four

leading wheel The leading wheel or leading axle or pilot wheel of a steam locomotive is an unpowered wheel or axle located in front of the driving wheels. The axle or axles of the leading wheels are normally located on a leading truck. Leading wheels are used ...

s, one set of four

driving wheel On a steam locomotive, a driving wheel is a powered wheel which is driven by the locomotive's pistons (or turbine, in the case of a steam turbine locomotive). On a conventional, non-articulated locomotive, the driving wheels are all coupled t ...

s, one set of six driving wheels, and a two

trailing wheel On a steam locomotive, a trailing wheel or trailing axle is generally an unpowered wheel or axle (Wheelset (rail transport), wheelset) located behind the driving wheels. The axle of the trailing wheels is usually located in a trailing Bogie, t ...

s. Other equivalent classifications are:

UIC classification The UIC classification of locomotive axle arrangements, sometimes known as the German classification''The Railway Data File''. Leicester: Silverdale, 2000. p. 52. . or German system,Kalla-Bishop P.M. & Greggio, Luciano, ''Steam Locomotives'', Cr ...

: 2BC1 (also known as German classification and

Swiss classification For more than a century, the Swiss locomotive, multiple unit, motor coach and railcar classification system, in either its original or updated forms, has been used to name and classify the rolling stock operated on the railways of Switzerland. ...

)
Italian and French classification: 220+031
The equivalent

is refined to (2′B)C1′ for Mallet locomotives. This wheel arrangement was rare. Two are known to have been built, both as compound

Mallet locomotives A Mallet locomotive is a type of compound articulated steam locomotive, invented by the Swiss engineer Anatole Mallet (1837–1919). The front of the locomotive is articulated on a bogie. The compound steam system fed steam at boiler pressu ...

Baldwin Locomotive Works The Baldwin Locomotive Works (BLW) was an American manufacturer of railway locomotives from 1825 to 1951. Originally located in Philadelphia, Pennsylvania, it moved to nearby Eddystone, Pennsylvania, Eddystone in the early 20th century. The com ...

in 1909 for the

Atchison, Topeka and Santa Fe Railway The Atchison, Topeka and Santa Fe Railway , often referred to as the Santa Fe or AT&SF, was one of the largest Class 1 railroads in the United States between 1859 and 1996. The Santa Fe was a pioneer in intermodal freight transport; at vario ...

. They were initially numbered 1300 and 1301 but soon re-numbered 1398 and 1399. These locomotives were perhaps the first and only attempt in North America to adapt the Mallet-compound design for passenger service, and when delivered were the world's largest passenger locos. With a weight of and driving wheels, they exerted tractive force. Designed to operate at , they achieved in tests."Locomotives You Didn't Expect to Meet on the Santa Fe Trail" ''

Trains A train (from Old French , from Latin">-4; we might wonder whether there's a point at which it's appropriate to talk of the beginnings of French, that is, when it wa ... , from Latin , "to pull, to draw") is a series of connected vehicles th ...

'' magazine, August 1963 But the experiment was unsuccessful: Adhesion stability was a problem, as the front engine tended to slip uncontrollably because of an imbalance of tractive effort at passenger-train speeds (this was a common problem with compound Mallets, at any speed much above walking pace). Both locomotives were rebuilt to non-compound

4-6-2 Under the Whyte notation for the classification of steam locomotives, represents the wheel arrangement of four leading wheels on two axles, six powered and coupled driving wheels on three axles and two trailing wheels on one axle. The locomoti ...

types in 1915, retained their assigned numbers, were still in use as of 1944, and retired by 1950. A somewhat more successful passenger Mallet design was a Russian 2-4-4-0 built between 1903 and 1909; the last examples were used into the 1950s.

References

{{commons category Atchison, Topeka and Santa Fe Railway locomotives Steam locomotives of the United States Railway locomotives introduced in 1915