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The 2-10-0 Decapod Type Steam Locomotive

The Decapod Type overall was not an extremely successful steam locomotive design, particularly if it were not for the large fleet of 2-10-0s the Pennsylvania Railroad would end up owning. Decapods biggest advantage was the fact that five of its six axles were powered thus providing very high tractive effort, a major factor if your railroad lies in mountainous territory (thus one reason that the Pennsylvania Railroad loved the 2-10-0 type). However, outside of this advantage Decapods had major flaws that caused most Class I railroads to shy away from them.

The Decapod Type was essentially an extension of the very successful Consolidation Type, a 2-8-0 design. The 2-8-0 design was a significant technological leap from the American, 4-4-0 wheel arrangement. The Consolidation, with its two extra driving axles and front pilot truck could not only pull trains that were twice as heavy but also run at speeds fast enough to be used in any type of passenger service. For instances, railroads such as the Baltimore & Ohio, Pennsylvania, and others, which operated in mountainous territory found that the Consolidation Type performed exemplary over stiff grades.

The first Decapods were built as early as 1867 for the Lehigh Valley Railroad. However, while a few different railroads (such as the Erie) would come to own the Decapod Type, the design was virtually a failure as its problems simply turned most railroads away. These problems included an inadequate firebox (thus the locomotive could not get proper combustion resulting in low horsepower) since it had to be situated between the wheels due to no trailing truck (meaning it was smaller than locomotives that included the trailing truck to support the weight of a heavier firebox). Another problem for the design was its small drivers that could not properly balance the incredible piston thrusts (needed for so many axles) causing not only very rough riding but also down right dangerous operation of speeds greater than 50 mph.

While only a handful of railroads ever used the 2-10-0 design the Pennsylvania loved it for its usefulness in mountainous territory due to its high adhesion output. In total the PRR would own a whopping 598 Decapod Types! Designated as their I-1 Class the railroad built 123 of its own with another 475 coming from Baldwin Locomotive Works, completing its fleet in the early 1920s. It should also be noted that the Western Maryland owned the heaviest Decapods to ever be built, which, like the PRR used them in heavy drag services.

Interestingly, as unsuccessful as the Decapod Type was in general across the industry it lasted on the Pennsy and other shortlines (which also found the 2-10-0 quite useful in drag service since it was relatively light weight and could negotiate lighter and less-maintained track) clear up until the end of the steam era in the 1950s.

Today, a number of Decapods have been preserved across the country and one is even still in operation, #90, of Great Western Railway lineage, operates annually on the famous Strasburg Railroad in the Pennsylvania Amish Country.

For more information on the Decapod Type steam locomotive consider How a Steam Locomotive Works by author Karen Parker, which explores in great detail how exactly each component of a steam locomotive works but is also easy enough to read for anyone to understand. The book has received excellent reviews and is a great resource on steam locomotives and a fine reference tool; you should find it very useful.

Also, consider the book American Steam Locomotives from author Brian Solomon. While this publication does not include quite as much technical data as Parker's book, How a Steam Locomotive Works, it is still a very good resource with lots of information and best of all, is loaded with photographs! If you're interested in perhaps purchasing either (or both) of these books please visit the links below which will take you to ordering information through Amazon.com, the trusted online shopping network.

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