Class D6 (formerly Class K, pre-1895) on the

Pennsylvania Railroad The Pennsylvania Railroad (reporting mark PRR), legal name The Pennsylvania Railroad Company also known as the "Pennsy", was an American Class I railroad that was established in 1846 and headquartered in Philadelphia, Pennsylvania. It was named ...

was a class of

4-4-0 4-4-0 is a locomotive type with a classification that uses the Whyte notation for the classification of steam locomotives by wheel arrangement and represents the arrangement: four leading wheels on two axles (usually in a leading bogie), four po ...

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 ...

. Nineteen were built by the PRR's Altoona Works (now owned by Norfolk Southern) between 1881–1883. They were equipped with drivers. Seven were later converted to drivers and classified D6a. The D6 was one of the first American 4-4-0s to place the

firebox Firebox may refer to: *Firebox (steam engine), the area where the fuel is burned in a steam engine *Firebox (architecture), the part of a fireplace where fuel is combusted *Firebox Records, a Finnish 8101705801record label * Firebox.com, an electro ...

above, rather than between, the locomotive's frames. This added about 8 inches to the possible width of the firebox, enabling a larger, easier to fire and more powerful locomotive; the maximum fire grate area increased to about from the previous maximum of about . The innovation was not wholly new, having been first seen on the Philadelphia and Reading Railroad's 1859 ''Vera Cruz'', designed by James Milholland of that road and built in their own shops; the Reading used this design until the invention of the

Wootten firebox The Wootten firebox is a type of firebox used on steam locomotives. The firebox was very wide to allow combustion of anthracite waste, known as " culm". Its size necessitated unusual placement of the crew, examples being camelback locomotives. The ...

in 1877. It was subsequently adopted 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 ...

in 1881 for six locomotives constructed for the Central of New Jersey; these were followed by the Pennsylvania Railroad locomotives, which garnered more attention for this design feature, in addition to having larger drivers than most previous 4-4-0s.

References

{{DEFAULTSORT:Pennsylvania Railroad class D06 4-4-0 locomotives D06 Railway locomotives introduced in 1881 Scrapped locomotives Standard gauge locomotives of the United States Steam locomotives of the United States