The Pennsylvania Railroad, 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. At its peak in 1882, the Pennsylvania Railroad was the largest railroad, the largest transportation enterprise, and the largest corporation in the world, on par with the London & North Western Railway.
Locomotive classification on the Pennsylvania Railroad took several forms. Early on, steam locomotives were given single-letter classes. As the 26 letters were quickly assigned, that scheme was abandoned for a more complex system. This was used for all of the PRR's steam locomotives, and — with the exception of the final type bought — all electric locomotives also used this scheme.
The Pennsylvania Railroad's class B6 was its most successful class of switcher locomotive, or as the PRR termed them "shifter". The PRR preferred the 0-6-0 wheel arrangement for larger switchers, whereas on other railroads the 0-8-0 gained preference. The PRR generally used 2-8-0s when larger power was required.
The Pennsylvania Railroad's S2 class was a steam turbine locomotive designed and built in a collaborative effort by Baldwin Locomotive Works and Westinghouse Electric & Manufacturing Company, as an attempt to prolong the dominance of the steam locomotive by adapting technology that had been widely accepted in the marine industry. One was built, #6200, delivered in September 1944. The S2 was the sole example of the 6-8-6 wheel arrangement in the Whyte notation, with a six-wheel leading truck keeping the locomotive stable at speed, eight powered and coupled driving wheels, and a six-wheel trailing truck supporting the large firebox. The S2 used a direct-drive steam turbine provided by the Westinghouse Electric & Manufacturing Company, geared to the center pair of axles with the outer two axles connected by side rods; the fixed gear ratio was 18.5:1. Such design was to prevent energy loss and S2 achieved a mechanical efficiency of 97% which means only 3% of steam energy was lost within the propulsion equipment. The disadvantage of a direct-drive steam turbine was that the turbine could not operate at optimal speeds over the locomotive's entire speed range. The S2 was the largest, heaviest and fastest direct-drive turbine locomotive design ever built.
The Pennsylvania-Reading Seashore Lines was a railroad that operated in South Jersey in the 20th century. It was created in 1933 as a joint consolidation venture between two competing railroads in the region: the Pennsylvania Railroad and the Reading Company.
Pennsylvania Railroad class E2b comprised six experimental B-B electric locomotives built for the railroad by General Electric.
The Pennsylvania Railroad's class B1 comprised 42 electric switcher locomotives built between 1926 and 1935. They were of 0-6-0 wheel arrangement in the Whyte notation with 700 horsepower. As built, the first 28 locomotives in the 1926 order formed semi-permanently coupled pairs grouped in three classes.
The Pennsylvania Railroad's class AA1 comprised two experimental electric locomotives constructed in 1905 by the company's own Altoona Works with the assistance of Westinghouse. Intended as testbeds as the PRR began its electrification project, both locomotives remained service into the 1930s.
Union Railroad is a Class III switching railroad located in Allegheny County in Western Pennsylvania. The company is owned by Transtar, Inc., which is a subsidiary of Fortress Transportation and Infrastructure Investors, after being acquired from U.S. Steel in 2021. The railroad's primary customers are the three plants of the USS Mon Valley Works, the USS Edgar Thomson Steel Works, the USS Irvin Plant and the USS Clairton Coke Works.
Class D16 on the Pennsylvania Railroad was their final development of the 4-4-0 "American" type of steam locomotive. A total of 429 of these locomotives were built at the PRR's Juniata Shops, spread across five subclasses; some had 80 in (2,030 mm) diameter driving wheels for service in level territory, while others had 68 in (1,730 mm) drivers for mountainous terrain. In the pre-1895 scheme, these locomotives were second class L.
The Pennsylvania Railroad Class E6 was the final type of 4-4-2 "Atlantic" locomotive built for the company, and second only to the Milwaukee Road's streamlined class A in size, speed and power. Although quickly replaced on the fastest trains by the larger K4s Pacifics, the E6 remained a popular locomotive on lesser services and some lasted until the end of steam on the PRR. One, #460, called the Lindbergh Engine, is preserved at the Railroad Museum of Pennsylvania. It was moved indoors to begin preparations for restoration on March 17, 2010. On January 10, 2011, PRR #460 was moved to the museum's restoration shop for a two- to three-year project, estimated to cost $350,000. The engine is listed in the National Register of Historic Places.
Class D7 (formerly Class A (anthracite), pre-1895) on the Pennsylvania Railroad was a class of 4-4-0 steam locomotive. Fifty-eight were built by the PRR's Altoona Works (now owned by Norfolk Southern) between 1882–1891 with 68 in (1.73 m) drivers, while sixty-one of class D7a were constructed with 62 in (1.57 m) drivers.
The Pennsylvania Railroad's steam locomotive class D1 comprised thirteen 4-4-0 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 Pennsylvania Railroad's steam locomotive class D2 comprised twenty 4-4-0 locomotives intended for mountain passenger helper service, constructed at the railroad's own Altoona Works during 1869–1880. They were the second standardized class of locomotives on the railroad and shared many parts with other standard classes.
The Pennsylvania Railroad's steam locomotive class D3 comprised sixty-seven 4-4-0 locomotives intended for general passenger and freight service, constructed at the railroad's own Altoona Works during 1869–1881. They were the third standardized class of locomotives on the railroad and the most numerous of the early standard types; they shared many parts with other standard classes.
The Pennsylvania Railroad's steam locomotive class D4 (formerly Class C (anthracite), pre-1895) comprised thirty-seven anthracite-burning 4-4-0 locomotives intended for general passenger and freight service on the PRR's New Jersey lines, constructed at the railroad's own Altoona Works (now owned by Norfolk Southern) during 1873–1890. They shared many parts with other standard classes.
The Manhattan Limited was a passenger train of the Pennsylvania Railroad which served the Chicago—New York City route.
The Pennsylvania Railroad's class H6, H6a, and H6b steam locomotives were of the 2-8-0 "Consolidation" freight type, the most numerous class on the railroad with 1,707 units and the second most prolific 2-8-0 class in North America, with the USATC S160 class rostering 88 units more. The three subclasses differed as follows:
The Pennsylvania Railroad's class A5s was the most powerful class of 0-4-0 steam locomotives. The Pennsylvania Railroad built 47 in its Juniata Shops between 1916–1924. They were all retired by 1957. One is preserved at the Railroad Museum of Pennsylvania.
The Pennsylvania Railroad (PRR) class CC2s consisted of ten 0-8-8-0 compound articulated (Mallet) type of steam locomotive built by Baldwin Locomotive Works in 1919 for PRR. These were used for transfer runs, and used for switching as "yard hump" power.
