The Pennsylvania Railroad

Pennsylvania Railroad

The Pennsylvania Railroad was an American Class I railroad, founded in 1846. Commonly referred to as the "Pennsy", the PRR was headquartered in Philadelphia, Pennsylvania....

's steam locomotive

Steam locomotive

A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...

 class D1 (formerly Class A, pre-1895) comprised thirteen 4-4-0

4-4-0

Under the Whyte notation for the classification of steam locomotives, 4-4-0 represents the wheel arrangement of four leading wheels on two axles , four powered and coupled driving wheels on two axles, and no trailing wheels...

 locomotives for express passenger service, constructed at the railroad's own Altoona Works during 1868–1872.
They were the first standardized class of locomotives on the railroad and shared many parts with other standard classes.

The PRR was the first American railroad to adopt the Westinghouse

Westinghouse Air Brake Company

The railway air brake was invented by George Westinghouse of New York state in 1869. Soon after, he moved to Pittsburgh, Pennsylvania, where he established the Westinghouse Air Brake Company on September 28, 1869...

 air brake, the first tests of which were made in September 1869; Class A locomotives were among those fitted with air brake equipment for those earliest tests.