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 (the E44) — 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.
*A1
*A2
*A3
*A4
*A5s
*A6
===B: 0-6-0===
Class B comprised the 0-6-0 type, the most popular arrangement for switchers on the PRR.
*B1
*B2
*B3
*B4
*B5 - Rebuilt from class H1 and H2a 2-8-0
*B6
*B7 - Some rebuilt from class H3, H3a, and H3b 2-8-0
*B8
*B21
*B22
*B23
*B28
*B29
===C: 0-8-0===
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.
*C1 - Largest 2-cylinder 0-8-0 ever built
*C29
*C30
*C31
===D: 4-4-0===
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
*D1
*D2
*D3
*D4
*D5
*D6
*D7
*D8
*D9
*D10
*D11
*D12
*D13
*D14
*D15 - Compound
*D16
*D21 - ex-Vandalia Railroad, built by Baldwin 1871-1873
*D22 - ex-Vandalia Railroad, built by Pittsburgh 1883-1889
*D23 - ex-Vandalia Railroad, built by Pittsburgh 1884
*D24 - ex-Vandalia Railroad, built by Rogers 1887
*D25 - ex-Vandalia Railroad, built by Pittsburgh 1890
*D26 - ex-Vandalia Railroad, built by Schenectady 1895-1899
*D30 - ex-Toledo, Walhonding Valley and Ohio Railroad, built by Rome 1890
*D31 - ex-Toledo, Walhonding Valley and Ohio Railroad, built 1892-1895
*D32 - Compound, ex-Toledo, Walhonding Valley and Ohio Railroad, built by Baldwin 1892
*D33
*D34 - ex-Cleveland and Marietta Railroad, built by Rome 1885
*D35 - ex-Cleveland and Marietta Railroad, built by Rome 1885
*D36 - ex-Cleveland and Marietta Railroad, built by Rogers 1885-1886
*D37 - ex-Cincinnati, Lebanon and Northern Railway, built by Baldwin 1894
*D38 - ex-Cincinnati, Lebanon and Northern Railway, built by Pittsburgh 1899
*D39 - ex-Grand Rapids and Indiana Railroad, built by Baldwin 1892-1893
*D61 - ex-Cleveland, Akron and Columbus Railway, built by Baldwin 1893
*"Odd D" #10003, an experimental electric locomotive.
===E: 4-4-2===
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.
*E1
*E2
*E3
*E4
*E5
*E6
*E7
*E21
*E22
*E23
*E28 - Compound
*E29 - Compound
*"de Glehn" #2512, a single experimental compound locomotive
===F: 2-6-0===
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.
*F1
*F2 - Compound
*F3
*F21
*F22
*F23
*F24
*F25
*F26
*F27
*F30
*F31
*F61
===G: 4-6-0===
*G1
*G2
*G3
*G4
*G5 - Largest 10 wheeler built. PRR constructed 90 for use in commuter service and then built 30 for their subsidiary the Long Island RR.
*G53 - Owned By subsidiary Long Island RR
===H: 2-8-0===
*H1
*H2
*H3
*H4
*H5
*H6
*H8
*H9
*H10
===I: 2-10-0===
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.
*I1s - heavy freight hauler.
===J: 2-6-2 and 2-10-4===
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 123 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.
*J1 - 2-10-4 freight locomotives.
*J28 - experimental 2-6-2 locomotives.
===K: 4-6-2===
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.
*K2 - 153 built at Altoona 1910-1911
*K3s - 30 built by Baldwin in 1913.
*K4s - 425 built by the PRR and Baldwin 1914-1928.
*K5 - 2 prototypes built
===L: 2-8-2===
Class L was assigned to the 2-8-2 "Mikado" type.
*L1s - freight twin to the famed K4s Pacific (575 built)
*L2s - the USRA standard light Mikado (5 built for PRR).
*L5 - PRR 2nd generation DC electric locomotive.
*L6 - PRR freight AC electric locomotives.
===M: 4-8-2===
*M1 - mixed-traffic Mountain type, latterly mostly used on fast freight.
===N: 2-10-2===
*N1s - Lines West heavy freight locomotive.
*N2s - USRA Standard 2-10-2, also used on Lines West.
===O: 4-4-4===
The 4-4-4 arrangement was rare anywhere, and on the PRR it was found only on eight experimental electric locomotives.
*O1 - experimental electric locomotives.
===P: 4-6-4===
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.
*P5 - mixed-traffic electric locomotive, succeeded by the GG1.
===Q: 4-4-6-4 or 4-6-4-4===
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.
*Q1 - experimental duplex freight locomotive.
*Q2 - duplex freight locomotive.
===R: 4-8-4===
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.
*R1 - experimental electric locomotive, surpassed by the GG1.
===S: 6-4-4-6 or 6-8-6===
Both S class locomotives were originally intended to only have four leading and trailing wheels, but for the S1 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.
*S1 - experimental duplex express passenger locomotive.
*S2 - experimental steam turbine locomotive.
===T: 4-4-4-4===
The duplex-drive T1 was the final class of steam locomotive constructed for the Pennsylvania Railroad, and possibly the most controversial.
*T1 - Duplex express passenger locomotive.
=== T: 4-8-4 ===
The PRR had never built any steam locomotives of the 4-8-4 "Northern" type, but there was one proposed design.
* T2 - What could have been the PRR's version of a 4-8-4 "Northern" type locomotive. Never built.
===Compound classifications===
The PRR classified articulated locomotives and joined locomotive units by using multiples of the previous classifications.
Non-Articulated steam:
*1320 - 2-2-2-0 locomotive, based on the London and North Western Railway's Dreadnought Class locomotive. One built.
Articulated steam:
*CC1s - 0-8-8-0 Mallet locomotive. Treated as two 0-8-0s for classification. One built.
*CC2s - 0-8-8-0 Mallet locomotive. 10 built.
*FG1 - What could have been the PRR's version of the Norfolk & Western class A 2-6-6-4 simple articulated locomotive. Never built.
*HC1s - 2-8-8-0 simple articulated locomotive. The PRR's only main-line articulated. One built.
*HH1s - 2-8-8-2 Mallet locomotive. Treated for classification purposes as two 2-8-0s back to back.
*HH1 - 2-8-8-2 Norfolk & Western class Y3 borrowed by PRR during World War II.
Articulated electric:
*AA1 - experimental 0-4-4-0 or B-B electric locomotives.
*BB1 - two-unit prototype AC electric 0-6-0+0-6-0 switching locomotive, later split into single units as class B1.
*BB2 - two-unit 0-6-0+0-6-0 DC electric switching locomotives, later split into single units as class B1.
*BB3 - two-unit 0-6-0+0-6-0 DC electric switching locomotives for LIRR, later split into single units as class B3.
*DD1 - two-unit DC electric locomotive, two 4-4-0 half-locomotives semi-permanently coupled back to back. Served between Manhattan Transfer and Penn Station, and to Sunnyside Yard.
*DD2 - experimental mixed-traffic AC electric locomotive, similar in overall design and appearance to GG1.
*FF1 - 2-6-6-2 (1-C+C-1) experimental electric locomotive, 1917. Too powerful.
*FF2 - 2-6-6-2 motor-generator AC electric locomotives acquired second-hand from the Great Northern Railway (their classes Y1 and Y1a) in 1956.
*GG1 - express passenger and freight electric locomotive, highly successful.
==Non-standard electric classification==
*E2b - experimental B-B General Electric-built AC electric locomotives (3 pairs built).
*E3b - experimental B-B-B Baldwin-Lima-Hamilton-Westinghouse AC/DC rectifier locomotives (1 pair built).
*E2c - experimental C-C Baldwin-Lima-Hamilton-Westinghouse AC/DC rectifier locomotives (1 pair built)
*E44 - 1960 C-C General Electric AC/DC rectifier freight locomotives.
The horsepower-based designation unique to the E44 would be retained and expanded by Penn Central to cover the former New Haven EF4s (E33) and EP5s (E40).
==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. 
::The class number system is as follows:
::The first letter stood for the manufacturer; A=Alco, B =Baldwin, G =General Electric, E =EMD, F =Fairbanks-Morse, and L =Lima.
::The second and third letters represented the type of service; S =switcher, F =Freight, P =passenger, :: PF=dual service, RS =road-switcher, and H =helper.
::The next number(s) were for horse power rounded to hundreds.
::The last letter, if used, was for model variations.
===Alco===
PRR Class	Builder's Model	Build date	Totalproduced	Wheelarrangement	Service 	Power output 	Notes
AS6 	S-1 	1947–1951 	40 	B-B 	Switcher	600 hp (450 kW) 	
AS10 	S-2 	1948–1954 	90 	B-B 	Switcher	1,000 hp (750 kW) 	22 units MU class AS10m
AS10a 	T-6 	1958 	6 	B-B 	Switcher	1,000 hp (750 kW) 	
AF15 	FA-1 	1948–1950 	8 	B-B 	Freight 	1,500 hp (1,120 kW)	
AF15 	FB-1 	1948–1950 	8 	B-B 	Freight 	1,500 hp (1,120 kW)	
AF16 	FA-2 	1951 	24 	B-B 	Freight 	1,600 hp (1,190 kW)	
AF16 	FA-2 	1951 	12 	B-B 	Freight 	1,600 hp (1,190 kW)	
AFP20 	PA-1 	1947 	10 	A1A-A1A 	Pass 	2,000 hp (1,490 kW)	many converted to Freight
AFP20 	PB-2 	1947 	5 	A1A-A1A 	Pass 	2,000 hp (1,490 kW)	many converted to Freight
ARS10 	RS-1 	1948–1952 	27 	B-B 	Freight 	1,000 hp (750 kW) 	5 units used in Pass service
ARS15 	RS-2 	1948 	6 	B-B 	Freight 	1,500 hp (1,120 kW)	ex D&H
ARS16 	RS-3 	1951–1955 	115 	B-B 	Freight 	1,600 hp (1,190 kW)	45 units used in Pass service
ARS16a 	RSD-4 	1952–1953 	6 	C-C 	Freight 	1,600 hp (1,190 kW)	
ARS18 	RS-11 	1956–1957 	32 	B-B 	Freight 	1,800 hp (1,340 kW)	
ARS18a 	RSD-12 	1957–1958 	25 	C-C 	Freight 	1,800 hp (1,340 kW)	
ARS20 	RS-11 	1956–1957 	6 	B-B 	Freight 	2,000 hp (1,490 kW)	
ARS24 	RSD-15 	1956 	6 	C-C 	Freight 	2,400 hp (1,790 kW)	
ARS24s 	RSD-7 	1955–1956 	5 	C-C 	Pass 	2,400 hp (1,790 kW)	
ARS24 	RS-27 	1962 	15 	C-C 	Freight 	2,400 hp (1,790 kW)	
AF24 	C-424 	1962 	1 	C-C 	Freight 	2,400 hp (1,790 kW)	
AF25 	C-425 	1964–1965 	31 	C-C 	Freight 	2,500 hp (1,860 kW)	
AF27 	C-628 	1965 	15 	C-C 	Freight 	2,500 hp (1,860 kW)	
AF30 	C-630 	1966 	15 	C-C 	Freight 	2,500 hp (1,860 kW)	
AF36 	C-636 	1968 	15 	C-C 	Freight 	2,500 hp (1,860 kW)	ordered but del to PC
===Baldwin Locomotive Works===
PRR Class	Builder's Model	Build date	Totalproduced	Wheelarrangement	Service 	Power output 	Notes
BS6 	VO-660 	1942–1945 	12 	B-B 	Switcher	600 hp (450 kW) 	
BS6 	DS-4-4-660 	1942–1945 	99 	B-B 	Switcher	660 hp (490 kW) 	
BS7 	DS-4-4-750 	1951 	24 	B-B 	Switcher	750 hp (560 kW) 	
BS7 	S8 	1951 	7 	B-B 	Switcher	750 hp (560 kW) 	
BS10 	VO 	1943–1945 	8 	B-B 	Switcher	1,000 hp (750 kW) 	
BS10 	DS-4-4-1000 	1948–1950 	137 	B-B 	Switcher	1,000 hp (750 kW) 	
BS12 	S-12 	1951–1956 	98 	B-B 	Switcher	1,200 hp (890 kW) 	
BS24 	RT-624 	1951–1954 	24 	C-C 	Transfer	2,400 hp (1,790 kW)	
BF15 	DR-4-4-1500 	1940–1950 	34 	B-B 	Freight 	1,500 hp (1,120 kW)	Cab (A) aka "Sharknose"
BF15 	DR-4-4-1500 	1940–1950 	34 	B-B 	Freight 	1,500 hp (1,120 kW)	Cab (B)
BF16 	RF-16 (A) 	1950–1952 	72 	B-B 	Freight 	1,600 hp (1,190 kW)	Cab (A) aka "Sharknose"
BF16 	RF-16 (B) 	1950–1952 	30 	B-B 	Freight 	1,600 hp (1,190 kW)	Cab (B)
BP60a 	DR-12-8-3000 	1947–1948 	24 	2-D-D-2 	Pass 	3,000 hp (2,240 kW)	converted to helper aka "Centipede"
BP20 	DR-6-4-2000 	1948 	18 	A1A-A1A 	Pass 	2,000 hp (1,490 kW)	Cab (A)
BP20 	DR-6-4-2000 	1948 	9 	A1A-A1A 	Pass 	2,000 hp (1,490 kW)	Cab (B)
BRS10 	DRS-4-4-1000 	1949–1950 	6 	B-B 	Pass 	1,000 hp (750 kW) 	
BRS12 	RS-12 	1951–1954 	8 	B-B 	Pass 	1,200 hp (890 kW) 	3 units used in Pass service
BRS15 	DRS-4-4-1500 	1950 	8 	B-B 	Pass 	1,500 hp (1,120 kW)	
BRS16 	AS-616 	1953–1955 	28 	C-C 	Pass 	1,600 hp (1,190 kW)	16 units used in Pass service
BRS24 	RT-624 	1951–1954 	22 	C-C 	Transfer	2,400 hp (1,790 kW)	
LRS25 	T2500 	1950–1951 	22 	C-C 	Transfer	2,500 hp (1,860 kW)	Built by Lima Locomotive Works
===General Electric===
PRR Class	Builder's Model	Build date	Totalproduced	Wheelarrangement	Service 	Power output 	Notes
GS4 	44 Ton 	1948–1950 	46 	B-B 	Switcher	400 hp (300 kW) 	
GF25 	U25B 	1965 	59 	B-B 	Freight 	2,500 hp (1,860 kW)	
GF25a 	U25C 	1965 	20 	C-C 	Freight 	2,500 hp (1,860 kW)	
GF28a 	U28C 	1966 	15 	C-C 	Freight 	2,800 hp (2,090 kW)	
GF30a 	U30C 	1967 	5 	C-C 	Freight 	3,000 hp (2,240 kW)	
===EMD===
PRR Class	Builder's Model	Build date	Totalproduced	Wheelarrangement	Service 	Power output 	Notes
ES6 	SW 	1937 	12 	B-B 	Switcher	600 hp (450 kW) 	
ES6 	SW1 	1942–1950 	85 	B-B 	Switcher	600 hp (450 kW) 	
ES10 	NW2 	1941–1948 	32 	B-B 	Switcher	1,000 hp (750 kW) 	
ES12 	SW7-SW9 	1950–1953 	84 	B-B 	Switcher	1,200 hp (890 kW) 	
ES12 	SW1200 	1957 	35 	B-B 	Switcher	1,200 hp (890 kW) 	
EF15 	F3A,F7A 	1947–1952 	203 	B-B 	Freight 	1,500 hp (1,120 kW)	Cab A unit
EF15 	F3B,F7B 	1947–1952 	107 	B-B 	Freight 	1,500 hp (1,120 kW)	Cab B unit
EPF15 	FP7A 	1952 	40 	B-B 	Pass 	1,500 hp (1,120 kW)	Cab A unit
EPF15 	FP7B 	1952 	14 	B-B 	Pass 	1,500 hp (1,120 kW)	Cab B unit
EP20 	E7A 	1945–1949 	46 	A1A-A1A 	Pass 	2,000 hp (1,490 kW)	Cab A unit
EP20 	E7B 	1945–1949 	14 	A1A-A1A 	Pass 	2,000 hp (1,490 kW)	Cab B unit
EP22 	E8A 	1950–1952 	74 	A1A-A1A 	Pass 	2,250 hp (1,680 kW)	Cab A unit
ERS15 	GP7 	1952–1953 	66 	B-B 	Freight 	1,500 hp (1,120 kW)	10 units used in Pass service
ERS15ax 	SD7 	1953 	2 	B-B 	Freight 	1,500 hp (1,120 kW)	
ERS17 	GP9 	1955–1959 	310 	B-B 	Freight 	1,750 hp (1,300 kW)	40 units no cab
ERS17a 	SD9 	1957–1958 	25 	C-C 	Freight 	1,750 hp (1,300 kW)	
EF22 	GP30 	1963 	52 	B-B 	Freight 	2,250 hp (1,680 kW)	
EF25 	GP35 	1964–1965 	119 	B-B 	Freight 	2,250 hp (1,680 kW)	
EF25a 	SD35 	1965 	40 	C-C 	Freight 	2,250 hp (1,680 kW)	
EF30a 	SD40 	1966 	65 	C-C 	Freight 	3,000 hp (2,240 kW)	
EF36 	SD45 	1966 	65 	C-C 	Freight 	3,600 hp (2,680 kW)	
EF20a 	GP38 	1967 	5 	B-B 	Freight 	2,000 hp (1,490 kW)	Built for PRSL
===Fairbanks-Morse===
PRR Class	Builder's Model	Build date	Totalproduced	Wheelarrangement	Service 	Power output 	Notes
FS10 	H10-44 	1948–1949 	55 	B-B 	Switcher	1,000 hp (750 kW) 	
FS12 	H12-44 	1952–1954 	16 	B-B 	Switcher	1,200 hp (890 kW) 	
FF20 	Erie Built 	1947–1948 	36 	A1A-A1A 	Freight 	2,000 hp (1,490 kW)	Cab A
FF20 	Erie Built 	1947–1948 	12 	A1A-A1A 	Freight 	2,000 hp (1,490 kW)	Cab B
FF16 	CF-16-4 	1950 	16 	B-B 	Freight 	1,600 hp (1,190 kW)	Cab A
FF16 	CF-16-4 	1950 	8 	B-B 	Freight 	1,600 hp (1,190 kW)	Cab B
FRS-16 	H16-44 	1952 	10 	B-B 	Freight 	1,600 hp (1,190 kW)	
FRS-20 	H20-44 	1948–1951 	38 	B-B 	Freight 	2,000 hp (1,490 kW)	
FRS-24 	H24-66 	1953–1954 	9 	C-C 	Freight 	2,400 hp (1,790 kW)	aka Train Master
Category:Locomotive classification systems
Category:Pennsylvania locomotives