Under the Whyte notation for the classification of steam locomotives, 2-10-0 represents the wheel arrangement of two leading wheels on one axle, ten powered and coupled driving wheels on five axles, and no trailing wheels. This arrangement was often named Decapod, especially in the United States, although this name was sometimes applied to locomotives of 0-10-0 "Ten-Coupled" arrangement, particularly in the United Kingdom. Notable German locomotives of this type include the war locomotives of Class 52.
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 M1 was a class of steam locomotive of the Pennsylvania Railroad (PRR). It was a class of heavy mixed-traffic locomotives of the 4-8-2 "Mountain" arrangement, which uses four pairs of driving wheels with a four-wheel guiding truck in front for stability at speed and a two-wheel trailing truck to support the large firebox needed for sustained power. Although built for both passenger and freight work, they spent most of their service lives hauling heavy high-speed freight trains. Many PRR men counted the M1 class locomotives as the best steam locomotives the railroad ever owned.
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-Reading Seashore Lines was a railroad that operated in southern New 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's class Q1 comprised a single experimental steam locomotive for dual service, #6130. PRR Board approves $595,000 for the construction of this experimental Class dual service locomotive on Oct,9 1940, it was built in March 1942, its streamlined shrouding, according to an interview of noted an interview of John W. Epstein, Special Projects Manager and vice president, Raymond Loewy & AssoC.,, was designed by Raymond Lowey, but due to WWII, there was no publicity about it. The Q1 was a duplex locomotive, it had a wheel arrangement of 4-6-4-4, comprising a four-wheel leading truck, two sets of driving wheels in a rigid locomotive frame, and a four-wheel trailing truck. The first group of six driving wheels was driven by a pair of cylinders mounted conventionally in front of them, while the rear four driving wheels were driven by cylinders mounted behind them on either side of the firebox.
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.
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 D6 on the Pennsylvania Railroad was a class of 4-4-0 steam locomotive. Nineteen were built by the PRR's Altoona Works between 1881–1883. They were equipped with 78-inch (1,981 mm) drivers. Seven were later converted to 72-inch (1,829 mm) drivers and classified D6a.
Class L1s on the Pennsylvania Railroad comprised 574 2-8-2 "Mikado" type steam locomotives constructed between 1914 and 1919 by the railroad's own Juniata Shops as well as the Baldwin Locomotive Works (205) and the Lima Locomotive Works (25). It was the largest class of 2-8-2 locomotives anywhere, although other railroads had more Mikados in total.
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 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 PRR J1 was a class of 2-10-4 or "Texas" type steam locomotives with 69 in (180 cm) driving wheels built between 1942 and 1944. The J1 had over 95,000 pounds-force (422.6 kN) of tractive effort, plus an additional 15,000 lbf (66.7 kN) if the booster engine was used.
The Pennsylvania Railroad G5s was a class of 4-6-0 steam locomotives built by the PRR's Juniata Shops in the mid-late 1920s. It was designed for passenger trains, particularly on commuter lines, and became a fixture on suburban railroads until the mid-1950s. The G5s was the largest and most powerful 4-6-0 locomotive, except for a single Southern Pacific 4-6-0 that outweighed it by 5500 lb.
The Pennsylvania Railroad's class E2, E3, E7 steam locomotives were of the 4-4-2 "Atlantic" passenger type, frequently called “light Atlantics” after the introduction of the heavier E6 Atlantics. All were similar in size and boiler capacity but differed in firebox type, valves and valve gear, and cylinder diameter. Classes E2 and E3 were built simultaneously. Starting in 1916 a rebuilding program converted ninety class E2a,b,c to class E7s by replacing slide valves with piston valves and increasing cylinder diameter from 20.5 to 22.5 inches. Fourteen class E2 were similarly converted to class E7sa. Ninety class E2a,d, E3a,d were converted to class E3sd. These improvements allowed many of the engines to remain in active service into the 1930s.
Pennsylvania Railroad's E1 class comprised three experimental Atlantic 4-4-2 locomotives built in 1899 to compete with the Reading Railroad on the Philadelphia, Pennsylvania, to Atlantic City, New Jersey, high-speed seashore passenger train service. These engines were designed as cab-center or camelback locomotives with wide fireboxes and 80" drivers that carried 50,000 lbs per axle. They proved capable in fast service but the inherent danger of separating the engineer from the fireman was unacceptable to the PRR so they were sold to their subsidiary the Long Island Rail Road in 1903. While the camelback design was unfavorable the Atlantic style proved to be everything the Pennsylvania Railroad needed at that time. They went on to acquire 596 additional units over the next fifteen years.
A duplex locomotive is a steam locomotive that divides the driving force on its wheels by using two pairs of cylinders rigidly mounted to a single locomotive frame; it is not an articulated locomotive. The concept was first used in France in 1863, but was particularly developed in the early 1930s by the Baldwin Locomotive Works, the largest commercial builder of steam locomotives in North America, under the supervision of its then chief engineer, Ralph P. Johnson.
