The Steam Locomotive Classification

The following table illustrates the Whyte notation for the classification of steam locomotives and gives you a quick guide to identify most of the significant locomotives operating on the American railroads. To understand "Wheel Arrangement" start at the front of the engine and count backward each wheel pair. So, a Northern locomotive would have 2 pairs of lead wheels, 4 pairs of large drive wheels, and 2 trailing pair of wheels under the cab. Thus making it 4-8-4!

At Auburn Heights we have two different classes of locomotives; 4-4-0 or Americans, and 4-8-4 Northerns. The table below has been hi-lighted to denote these two classes.

The American Class of Locomotives

The 4-4-0 was

The Northern Class of Locomotives

The 4-8-4 was an obvious progression from the 4-8-2 "Mountain" and the 4-6-4 "Hudson" types, combining the 4-8-2's ability to have more weight on the driving wheels (leading to greater traction, and allowing a larger, more powerful locomotive) and the 4-6-4's larger firebox supported by a 4-wheel trailing truck, allowing for freer steaming, particularly at speed.

The first 4-8-4 was produced in 1927 by Alco for the Northern Pacific Railway, and the type was therefore named "Northern". Southern railroads in particular obviously didn't find this name very suitable, so they chose other names for their 4-8-4 classes.

The 4-8-4 was the ultimate wheel configuration for the modern passenger and fast freight steam locomotive. The eight driver arrangement was usable on almost every main line in North America and with drivers up to 80 inches in diameter allowed any reasonable speed that the railroad could handle. The four wheel trailing truck supported a larger firebox for maximum steam levels allowing for extra boiler capacity. The four wheel leading (or pony) truck completed the best combination for riding and tracking.

With the surge in passenger business in the 1920's most railroads were being forced to operate extra trains or run their scheduled trains in sections simply because the locomotives in use could only haul about 12 cars. It was out of this need that the "super powered" locomotives were developed and of them the 4-8-4 was the most numerous and widely used.

The first 4-8-4 was built by the American Locomotive Company, in January, 1927, for the Northern Pacific. This locomotive was basically the 4-8-2 modified to accommodate a large grate area and a very deep firebox which was required to burn the very low grade of bituminous coal that the Northern Pacific produced from its own mines. This new wheel arrangement was dubbed "Northern Pacific", which was quickly shortened to "Northern".

There were 36 North American Railroads that owned and operated a total of 1,126 "Northern" type locomotives.

Some railroads, particularly the southern ones, rejected the "Northern" name and used names with a more regional connection. The C&O called them "Greenbriers"; the Delaware, Lackawanna & Western used the name "Poconos"; the Lehigh Valley came up with "Wyoming"; the Nashville, Chattanooga & St.Louis named them "Dixies"; the New York Central chose "Niagaras"; the Richmond, Fredericksburg & Potomac named each of its 27, 4-8-4s after southern generals, governors and statesmen; the Southern Pacific used the name "Golden State"; the Western Maryland dubbed them "Potomacs" and in Canada, the CNR named them "Confederations" while the Nacionale de Mexico called them "Niagras".

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