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 ...

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 ...

class D2 (formerly Class B, pre-1895) comprised twenty

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 ...

locomotives intended for mountain

passenger A passenger (also abbreviated as pax) is a person who travels in a vehicle, but does not bear any responsibility for the tasks required for that vehicle to arrive at its destination or otherwise operate the vehicle, and is not a steward. The ...

helper service, constructed at the railroad's own Altoona Works (now owned by Norfolk Southern) during 1869–1880. They were the second standardized class of locomotives on the railroad and shared many parts with other standard classes. This design differed from the Class A (later D1) mainly in its smaller drivers for greater

tractive effort As used in mechanical engineering, the term tractive force can either refer to the total traction a vehicle exerts on a surface, or the amount of the total traction that is parallel to the direction of motion. In railway engineering, the term tr ...

in mountainous terrain. Like all the early standardized 4-4-0s on the PRR, the Class B had a wagon-top boiler with steam dome and a

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 ...

between the two driving axles. In 1881, the PRR took the Class B design and modified it to produce more locomotives for express passenger service, with drivers like the earlier Class A. These new locomotives were designated Class B A, and were classified as D2a in the post-1895 scheme; forty-five of them were constructed.

References

{{DEFAULTSORT:Prr D02 4-4-0 locomotives D02 Railway locomotives introduced in 1869 Scrapped locomotives Standard gauge locomotives of the United States Steam locomotives of the United States