Southern Pacific 4294, a cab-forward steam locomotive

Under the

Whyte notation 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 twentieth ce ...

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, oil or, rarely, wood) to heat water in the locomot ...

s, a 4-8-8-2 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, two sets of eight

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 ...

s, and a two-wheel

trailing truck On a steam locomotive, a trailing wheel or trailing axle is generally an unpowered wheel or axle ( wheelset) located behind the driving wheels. The axle of the trailing wheels is usually located in a trailing truck. On some large locomotives, ...

. 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'', Cre ...

: 2DD1 (also known as German classification and

Italian 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'', Cre ...

)

French classification Under the French classification system for locomotive wheel arrangements, the system is slightly different for steam and electric/diesel vehicles. Steam The French system counts axles, rather than wheels. As with Whyte notation, a conventional r ...

: 240+041

Turkish classification In the Turkish classification system for railway locomotives, the number of powered axles are followed by the total number of axles. It is identical to the Swiss system except that the latter places a slash between the two numbers. Thus 0-6-0 beco ...

: 46+45

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. ...

: 4/6+4/5 The equivalent

is refined to (2'D)D1' for Mallet locomotives. A locomotive of that length must be an

articulated locomotive An articulated locomotive is a steam locomotive (rarely, an electric locomotive) with one or more engine units that can move independent of the main frame. Articulation allows the operation of locomotives that would otherwise be too large to neg ...

; meaning all have a joint between the first and second groups of driving wheels. All examples of this type are cab forwards. Normally, the leading truck sits under the smokebox and the trailing truck under the firebox. On a cab-forward, the leading truck supports the firebox and the trailing truck and smokebox are at the rear next to the tender. A 4-8-8-2 is effectively a 2-8-8-4 that always runs in reverse.

Southern Pacific

The

Southern Pacific The Southern Pacific (or Espee from the railroad initials- SP) was an American Class I railroad network that existed from 1865 to 1996 and operated largely in the Western United States. The system was operated by various companies under the ...

was the only railroad to operate engines of this wheel arrangement, all of which were built by the

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

. A total of 195 were produced between 1928 and 1944 in eight batches. The later ones had cylinders 24 inches by 32 inches, drivers 63-1/2 inches and boiler pressures of 250 psi, giving a calculated tractive effort of 123,400 lb. The locomotives were built as cab-forwards to protect engine crews from exhaust smoke and heat in the many tunnels and

snow shed Avalanche control or avalanche defense activities reduce the hazard avalanches pose to human life, activity, and property.Mallets A mallet is a tool used for imparting force on another object, often made of rubber or sometimes wood, that is smaller than a maul or beetle, and usually has a relatively large head. The term is descriptive of the overall size and propor ...

'' these cab-forwards were built with simple expansion cylinders. The name stuck because the original classes of Southern Pacific cab-forwards were built as compound Mallets, though these were eventually converted to simple expansion machines.

Southern Pacific 4294 Southern Pacific 4294 is a class " AC-12" 4-8-8-2 Cab forward type steam locomotive that was owned and operated by the Southern Pacific Railroad (SP). It was built by the Baldwin Locomotive Works in March 1944 and was used hauling SP's trains o ...

is the only cab forward that was not scrapped when the locomotives were withdrawn from service. It was donated to the City of

Sacramento, California ) , image_map = Sacramento County California Incorporated and Unincorporated areas Sacramento Highlighted.svg , mapsize = 250x200px , map_caption = Location within Sacramento C ...

in 1958, but had to be moved due to freeway construction. It was subsequently given to the State of California, and is on indoor static display at the

California State Railroad Museum The California State Railroad Museum is a museum in the state park system of California, United States, interpreting the role of the "iron horse" in connecting California to the rest of the nation. It is located in Old Sacramento State Historic ...

in Sacramento.

References

General reference

External links

Web Site of ToyTrains1 4-8-8-2 Cab Forward Steam LocomotivesSteam Locomotive.com's Southern Pacific Cab Forward article, including detailed specs.
{{Whyte types 88,4-8-8-2 Simple articulated locomotives