4-8-4

The Northerns are steam locomotives that represents the wheel arrangement of four leading wheels on two axles, eight powered and coupled driving wheels on four axles and four trailing wheels on two axles. The type was first used by the Northern Pacific Railway, and initially named the Northern Pacific, but railfans and railroad employees have shortened the name when referring to the type, and now is most commonly known as a "Northern".
The 4-8-4 wheel arrangement was a progression from the 4-8-2 Mountain type and, like the 2-8-4 Berkshire and 4-6-4 Hudson types, an example of the "Super Power" concept in steam locomotive design that made use of the larger firebox that could be supported by a four-wheel trailing truck, which allowed greater production of steam. The four-wheel leading truck gave stability at speed and the eight driving wheels gave greater adhesion. The evolution to the 4-8-4 type occurred in the United States of America soon after the Lima Locomotive Works introduced the concept of "Lima Super Power" in 1925, making heavy 2-8-2 and 2-8-4 locomotives. The prototype was built by American Locomotive Company (ALCO) for the Northern Pacific Railway (NP) in 1926, with a very large firebox with a 100-square-foot (9.3 m2) grate, designed to burn low quality lignite coal. The four-wheel trailing truck weighed about 15,000 pounds (6.8 t) more than two-wheel trucks of the time and could carry an additional 55,000 pounds (25 t) of engine weight; the difference of 40,000 pounds (18 t) was available for increased boiler capacity.
The stability of the 4-8-4 wheel arrangement meant that driving wheels up to 80 inches (2.0 m) diameter could be used for high speed passenger and fast freight operation. Lateral control devices allowed these locomotives to traverse relatively sharp curves despite their eight-coupled drivers. The increased boiler size possible with this type, together with the high axle loads permitted on mainlines in North America, resulted in the design of some massive locomotives, some of which weighed more than 350 tons with tender included. The 4-8-4 was suitable for both express passenger and fast freight service, though it was not suited to heavy drag freight trains.
==Trivia==
*Union Pacific 844, is the only steam locomotive, and the only Northern Type that was never retired by a North American Class I railroad, though there are more than a few (4449 Southern Pacific, Reading No. 2101, etc.) that still haven't been scrapped.
*Australia has a total of 23 4-8-4 locomotives that operated in Australia, built to three distinct designs.
*By far the largest fleet in North America was owned by the CN and its subsidiary, the Grand Trunk Western Railroad, with altogether 203 locomotives. The Rock Island owned the largest fleet in the United States, numbering 65 engines by the time the class was complete in 1944.
*The US railroads to not own 4-8-4s included:
**Nickel Plate Road
**Pennsylvania Railroad
**Pere Marquette
**Boston & Maine
**Maine Central
**The Texas & Pacific
*A Delaware, Lackawanna, & Western 4-8-4 was offered to the City of Scranton, but the plans were cancelled when it proved to be too big and too difficult to move to Nay Aug park where it was meant to be put on display.
*CN #6153: On static display at the Canadian Railway Museum in Delson, Quebec.
==See also==
*4-8-4/Gallery
Category:Steam locomotives
Category:Tender locomotives
Category:4-8-4 locomotives
Category:4-8-4 steam locomotives
Category:Eight-coupled locomotives
Category:Australian Locomotives
Category:American locomotives
Category:Northern Pacific locomotives
Category:Santa Fe locomotives
Category:Union Pacific locomotives
Category:Southern Pacific locomotives
Category:Rio Grande locomotives
Category:SP&S locomotives
Category:Norfolk and Western locomotives
Category:Locomotives
Category:Grand Trunk Western locomotives
Category:Standard gauge locomotives
Category:Wheel arrangements
Category:New York Central locomotives
Category:Frisco locomotives