Pennsylvania Railroad locomotive classification


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.

PRR steam and electric classification

A: 0-4-0

Class A was the 0-4-0 type, an arrangement best suited to small switchers. Most railroads abandoned the 0-4-0 after the 1920s, but the PRR kept it for use on small industrial branches, especially those with street trackage and tight turns.
Class B comprised the 0-6-0 type, the most popular arrangement for switchers on the PRR.
Class C was assigned to the 0-8-0 type. These were very common on other railroads, but the PRR was not keen on them and only built a few. This was partly because the PRR used 2-8-0 "Consolidation" types for similar service.
Class D was the 4-4-0 "American" type, the most common arrangement in 19th Century American railroading. 4-4-0s stayed in service on the PRR in secondary work later than on most other railroads, and three were in use until after World War II
The 4-4-2 "Atlantic" type was assigned class E. The PRR was an enthusiastic user of the Atlantic type in flatter country, and built some of the most advanced Atlantics used in the United States.
The 2-6-0 "Mogul" type was assigned class F. On the PRR, this type was used during the period of 1895-1925, approximately. They were mostly used to haul express freight, although some hauled suburban passenger trains.
The 2-10-0 "Decapod" type was assigned class I. The PRR only owned one type of Decapod, class I1s, but they owned 598 of them, one of the largest classes of identical power in the United States.
Class J was first used for two experimental 2-6-2 "Prairie" locomotives built by ALCO in 1905. These were both withdrawn from service by the mid-1920s. In 1942, the PRR built 125 2-10-4 "Texas" type locomotives based on C&O plans; class J now being unoccupied, it was reused for them. The PRR J1 was an improved version of its C&O counterpart with more pulling power.
The PRR assigned class K to the 4-6-2 "Pacific" type. The Pacific was the most common type of passenger locomotive on the Pennsylvania.
Class L was assigned to the 2-8-2 "Mikado" type.
The 4-4-4 arrangement was rare anywhere, and on the PRR it was found only on eight experimental electric locomotives.
The 4-6-4 arrangement was seen on the PRR only on electric locomotives. As a steam locomotive arrangement, it was poorly suited to the PRR's mountainous terrain, wasting much potential adhesive weight on non-driven wheels. That it was so widely used by the rival New York Central would also likely have factored against PRR adoption.
The Q class comprised what were effectively 4-10-4s with the driving axles split into two driven groups. The Q2 was the most powerful non-articulated steam locomotive ever built and also holds the record for highest horsepower recorded by any steam locomotive at 7,987 hp.
The PRR never built any steam locomotives of the 4-8-4 "Northern" type, although the T1 duplexes were effectively a "Northern" with the driving wheels split into two groups.
Both S class locomotives were originally intended to only have four leading and trailing wheels, but increases in weight required an additional axle at each end. In the case of the S2, it was due to wartime limits on the use of advanced steel alloys.
The duplex-drive T1 was the final class of steam locomotive constructed for the Pennsylvania Railroad, and possibly the most controversial.
The PRR classified articulated locomotives and joined locomotive units by using multiples of the previous classifications.
Non-Articulated steam:
Articulated steam:
Articulated electric:
The horsepower-based designation unique to the E44 would be retained and expanded by Penn Central to cover the former New Haven EF4s and EP5s.

Diesel classification

The Pennsylvania Railroad was slow to dieselize. By the end of WW2 they only had 18 units. However over the next 22 years they had acquired a total of 3005 units. They bought from all the manufacturers: Alco 516 units, Baldwin 643 units, EMD 1,479 units, Fairbanks-Morse 200 units, General Electric 145 units, and Lima 22 units. This diversity was a nightmare for the maintenance department as there was very little compatibility amongst the different builders.

Alco

PRR ClassBuilder’s ModelBuild dateTotal
produced		Wheel
arrangement		ServicePower outputNotes
AS6S-11947–195140B-BSwitcher
AS10S-21948–195490B-BSwitcher22 units MU class AS10m
AS10aT-619586B-BSwitcher
AF15FA-11948–19508B-BFreight
AF15FB-11948–19508B-BFreight
AF16FA-2195124B-BFreight
AF16FA-2195112B-BFreight
AFP20PA-1194710A1A-A1APassmany converted to Freight
AFP20PB-219475A1A-A1APassmany converted to Freight
ARS10RS-11948–195227B-BFreight5 units used in Pass service
ARS15RS-219486B-BFreightex D&H
ARS16RS-31951–1955115B-BFreight45 units used in Pass service
ARS16aRSD-41952–19536C-CFreight
ARS18RS-111956–195732B-BFreight
ARS18aRSD-121957–195825C-CFreight
ARS20RS-111956–19576B-BFreight
ARS24RSD-1519566C-CFreight
ARS24sRSD-71955–19565C-CPass
ARS24RS-27196215C-CFreight
AF24C-42419621C-CFreight
AF25C-4251964–196531C-CFreight
AF27C-628196515C-CFreight
AF30C-630196615C-CFreight
AF36C-636196815C-CFreightordered but del to PC

Baldwin Locomotive Works

PRR ClassBuilder’s ModelBuild dateTotal
produced		Wheel
arrangement		ServicePower outputNotes
BS6VO-6601942–194512B-BSwitcher
BS6DS-4-4-6601942–194599B-BSwitcher
BS7DS-4-4-750195124B-BSwitcher
BS7S819517B-BSwitcher
BS10VO1943–19458B-BSwitcher
BS10DS-4-4-10001948–1950137B-BSwitcher
BS12S-121951–195698B-BSwitcher
BF15DR-4-4-15001940–195034B-BFreightCab aka “Sharknose”
BF15DR-4-4-15001940–195034B-BFreightCab
BF16RF-16 1950–195272B-BFreightCab aka “Sharknose”
BF16RF-16 1950–195230B-BFreightCab
BP60aDR-12-8-30001947–1948242-D-D-2Passconverted to helper aka "Centipede"
BP20DR-6-4-2000194818A1A-A1APassCab
BP20DR-6-4-200019489A1A-A1APassCab
BRS10DRS-4-4-10001949–19506B-BPass
BRS12RS-121951–19548B-BPass3 units used in Pass service
BRS15DRS-4-4-150019508B-BPass
BRS16AS-6161953–195528C-CPass16 units used in Pass service
BRS24RT-6241951–195422C-CTransfer
LRS25T25001950–195122C-CTransferBuilt by Lima Locomotive Works

General Electric

PRR ClassBuilder’s ModelBuild dateTotal
produced		Wheel
arrangement		ServicePower outputNotes
GS444 Ton1948–195046B-BSwitcher-
GF25U25B196559B-BFreight
GF25aU25C196520C-CFreight
GF28aU28C196615C-CFreight
GF30aU30C19675C-CFreight

EMD

PRR ClassBuilder’s ModelBuild dateTotal
produced		Wheel
arrangement		ServicePower outputNotes
ES6SW193712B-BSwitcher
ES6SW11942–195085B-BSwitcher
ES10NW21941–194832B-BSwitcher
ES12SW7-SW91950–195384B-BSwitcher
ES12SW1200195735B-BSwitcher
EF15F3A,F7A1947–1952203B-BFreightCab A unit
EF15F3B,F7B1947–1952107B-BFreightCab B unit
EPF15FP7A195240B-BPassCab A unit
EPF15FP7B195214B-BPassCab B unit
EP20E7A1945–194946A1A-A1APassCab A unit
EP20E7B1945–194914A1A-A1APassCab B unit
EP22E8A1950–195274A1A-A1APassCab A unit
ERS15GP71952–195366B-BFreight10 units used in Pass service
ERS15axSD719532B-BFreight
ERS17GP91955–1959310B-BFreight40 units no cab
ERS17aSD91957–195825C-CFreight
EF22GP30196352B-BFreight
EF25GP351964–1965119B-BFreight
EF25aSD35196540C-CFreight
EF30aSD40196665C-CFreight
EF36SD45196665C-CFreight
EF20aGP3819675B-BFreightBuilt for PRSL

Fairbanks-Morse

PRR ClassBuilder’s ModelBuild dateTotal
produced		Wheel
arrangement		ServicePower outputNotes
FS10H10-441948–194955B-BSwitcher
FS12H12-441952–195416B-BSwitcher
FF20Erie Built1947–194836A1A-A1AFreightCab A
FF20Erie Built1947–194812A1A-A1AFreightCab B
FF16CF-16-4195016B-BFreightCab A
FF16CF-16-419508B-BFreightCab B
FRS-16H16-44195210B-BFreight
FRS-20H20-441948–195138B-BFreight
FRS-24H24-661953–19549C-CFreightaka Train Master