The Pennsylvania Railroad was an American Class I railroad that was established in 1846 and was headquartered in Philadelphia, Pennsylvania. It was so named because it was established in the Commonwealth of Pennsylvania.
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, or as the PRR termed them, "shifter". The PRR preferred the 0-6-0 wheel arrangement for larger switchers, whereas on other roads the 0-8-0 gained preference. The PRR used road locomotives, generally 2-8-0s, when larger power was required.
The Pennsylvania Railroad's class P5 comprised 92 mixed-traffic electric locomotives constructed 1931–1935 by the PRR, Westinghouse and General Electric. Although the original intention was that they work many passenger trains, the success of the GG1 locomotives meant that the P5 class were mostly used on freight. A single survivor, prototype #4700, is at the National Museum of Transportation in St Louis, Missouri.
The Pennsylvania Railroad's class O1 comprised eight experimental boxcab electric locomotives built in 1930 and 1931. They were built in preparation for the New York to Washington Electrification project. They had the wheel arrangement classified as 4-4-4 in the Whyte notation. Although successful, they were not powerful enough for the railroad's increasingly heavy trains. For production, the PRR chose to concentrate on the P5 class, effectively an enlarged and more powerful version of the O1 with an additional pair of driving wheels.
The Pennsylvania Railroad DD1 was a class of boxcab electric locomotives built by the Pennsylvania Railroad. The locomotives were developed as part of the railroad's New York Tunnel Extension, which built the original Pennsylvania Station in New York City and linked it to New Jersey via the North River Tunnels. The Pennsylvania built a total of 66 locomotives in its Altoona Works; they operated in semi-permanently coupled pairs. Westinghouse supplied the electrical equipment.
The Pennsylvania Railroad's class DD2 electric locomotive was a single prototype locomotive never placed into series production. It was intended as an improved and simplified GG1 for use on the planned, but never built, extension of the PRR's electrification west of Harrisburg, Pennsylvania. The one locomotive produced was numbered #5800 and used in regular Baltimore tunnel helper service until it was scrapped in September 1962.
The Great Northern Railway's class Y-1 comprised eight electric locomotives with AAR 1-C+C-1 wheel arrangements. The locomotives were used on the 73-mile (117 km) electrified portion of the railroad, from Wenatchee, Washington to Skykomish, Washington, including the Cascade Tunnel.
The Pennsylvania Railroad's class FF1 was an American electric locomotive, a prototype numbered #3931 and nicknamed "Big Liz". It was built in 1917 to haul freight trains across the Allegheny Mountains where the PRR planned to electrify. "Big Liz" proved workable but too powerful for the freight cars of the time with its 4600 available horsepower and astonishing 140,000 lbf (620 kN) of tractive effort. Pulling the train it regularly snapped couplers and when moved to the rear as a pusher its force was sufficient to pop cars in the middle of the train off the tracks.
Pennsylvania Railroad class E2b comprised six experimental B-B electric locomotives built for the railroad by General Electric.
The Pennsylvania Railroad's class R1 comprised a single prototype electric locomotive constructed in 1934 by the Baldwin Locomotive Works of Philadelphia, Pennsylvania, USA, with the electrical equipment by Westinghouse.
The Pennsylvania Railroad's class L5 were the railroad's second generation of production electric locomotives after the DD1, and the last to use a jackshaft and side rods to drive the wheels. The L5 was a single-unit locomotive instead of the twin-unit DD1. The wheel arrangement in Whyte notation was 2-4-4-2, or 1-B-B-1 in the AAR scheme. Twenty five were built in 4 distinct subclasses. The lead unit of the class was equipped for AC operation with an overhead pantograph, while the other 24 were third rail DC units to work on the existing PRR third rail electrification in the New York area.
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.
Pennsylvania Railroad's Odd D #10003 was an experimental electric locomotive built in 1907 by Baldwin and Westinghouse. It had a 4-4-0 wheel arrangement in the Whyte notation, or 2-B in the AAR scheme. On the PRR, class D was assigned to 4-4-0 locomotives. Production classes of locomotive were assigned a number after the letter, but one-off locomotives were simply designated "Odd".
The class D15 of the Pennsylvania Railroad comprised a solitary Lindner-system cross compound steam locomotive of 4-4-0 "American" wheel arrangement in the Whyte notation. The sole locomotive was #1515, built in 1892 at the PRR's Altoona Shops, it had very British lines with a full-length footplate, splashers, a six-wheel tender, and large 84 in (2,134 mm) drivers. It was built in 1892 by the PRR’s Altoona Works it remained in service until it was retired in 1945 and put in storage at the PRR’s Altoona Works and was scrapped in 1951.
Class D14 on the Pennsylvania Railroad was a type of steam locomotive with a 4-4-0 wheel arrangement in the Whyte notation. They were originally designated class P in the PRR's pre-1895 classification scheme. Twenty-two locomotives were built at the PRR's Altoona Works ; six in 1893 with 78-inch (1,981 mm) driving wheels, and sixteen in 1894 with 80-inch (2,032 mm) drivers, classified D14a. Later, all sixteen class D14a were rebuilt to class D14b with 68-inch (1,727 mm) drivers for secondary service after they were replaced in top-flight express service, while three of the six class D14 were similarly rebuilt to class D14c.
Class D7 on the Pennsylvania Railroad was a class of 4-4-0 steam locomotive. Fifty-eight were built by the PRR's Altoona Works 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 MP54 was a class of electric multiple unit railcars. The class was initially constructed as an unpowered, locomotive hauled coach for suburban operations, but were designed to be rebuilt into self-propelled units as electrification plans were realized. The first of these self-propelled cars were placed in service with the PRR subsidiary Long Island Rail Road with DC propulsion in 1908 and soon spread to the Philadelphia-based network of low frequency AC electrified suburban lines in 1915. Eventually the cars came to be used throughout the railroad's electrified network from Washington, D.C. to New York City and Harrisburg, Pennsylvania.
The Pennsylvania Railroad's class A5s was the largest 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.
P-Motor was the class designation given by the New York Central a fleet of 22 ALCO-GE electric passenger locomotives. The P Motors were not only more powerful than previous New York Central electrics, but also a more advanced design using the highly successful 2-C+C-2 wheel arrangement found on the later PRR GG1 and New Haven EP-3 classes as well as nose suspended traction motors. Although originally built and owned by a consortium of railroads involved in the large scale Cleveland Union Terminal project, the New York Central was the majority owner and later acquired them outright in the 1950s when the Terminal's electrification scheme was scrapped in favor of diesels. Rebuilt and re-classified as P-2, the 21 remaining engines were sent to the New York electrified zone to supplement the aging fleet of T-Motors that had been purchased starting in 1913. There they played out the remainder of their careers pulling the Central's premier passenger trains.
