Atlantic Coast Line 4-6-2 "Pacific" Type Locomotives


Class J - The First "Pacifics" on the ACL

The Rhode Island Locomotive Works built three 4-6-2 cross-compond locomotives in 1893 and delivered them to the Chicago, Milwaukee & St. Paul Railroad. The CM&St.P was not satisfied with the perfomance of these locomotive and returned them to the builder. They were rebuilt as simple locomotives and purchased for passenger servce on the SF&W Railway. The Atlantic Coast Line acquired the three locomotives in 1902 and assigned them road numbers 287 through 289 and designated them as Class J. These locomotives had 19x26 cyinders, 72" drivers, a 165 psi boiler pressure, exerted 20,000 lbs of tractive effort and each weighed 139,000 pounds. In 1912,the ACL rebuilt the Class J locomotives into 4-6-0s, renumbered them 1287 through 1289 and designated them as Class K-13.

Classes: P, P-1, P-2, P-3, P-4, P-5A & P-5B Passenger and Freight "Pacifics"

The Atlantic Coast Line took delivery of 15 "Pacific" type locomotives, in 1911, from the Baldwin Locomotive Works. these locomotives were given road numbers 260 through 274 and were designated as Class P. They had 73" diameter driver and were designed to be main line passenger motive power. As originally built they used saturated steam, had D-slide valves, Walschaert valve gear, 22x28 cylinders and a 185 psi boiler pressure. They exerted 29,600 lbs of tractive effort and each weighed 220,850 pounds. Later these "Pacifics" were rebuilt with superheaters and the designation was changed to P-S.

Twelve more "Pacifics", intended for passenger service, arrived from Baldwin in 1912 and were assigned road numbers 275 through 286 and designated as Class P-1. These locomotives had superheaters and were similar to the Class P-S locomotives. They each weighed 225,000 lbs and with 22x28 cylinders, 73" drivers and a boiler pressure of 200 psi exerted 31,600 lbs of tractive effort.

In 1913, the ACL received eleven 4-6-2 locomotives that were designed and intented for freight service and to also be used to pull high speed passenger trains. They were designated as Class P-2 and deivered with road numbers 287 through 297. Later to distiquish them from the passenger "Pacifics" they were renumbered 400 through 410. These freight haulers had 22x28 cylinders, 64" drivers, a 200 psi boiler pressure, exerted 36,000 lbs of tractve effort and each weighed 225,900 pounds.

The Class P-2 locomotives did not do well as dual purpose locomotives and the ACL ordered yet another design and in 1914 it took delivery of 45 dual purpose "Pacifics" from Baldwin. The group was desinated as Class P-3 and assigned road numbers 411 through 455. The P-3 locomotives had 22x28 cylinders, 69" drivers, a 200 psi boiler pressure, exerted 33,400 lbs of tractive effort and each weighed 226,800 pounds. They were very sucessful as dual purpose locomotives and 27 similar ones were delivered by Baldwin between 1916 and 1918. This group designated Class P-4 was given road numbers 456 through 482. They had 23x28 cylinders and each weighed about 17,000 pounds more than the Class P-3 locomotives.

Shortly after the close of World War I, the ACL took delivery of 70 USRA "Pacifics" which were built by the American Locomotive Company. They were designated as Class P-5A and assigned road numbers 1500 through 1569. These locomotives had 25x28 cylinders, 73" drivers, a 200 psi boiler pressure, exerted 40,750 lbs of tractive effort and each weighred 278,000 pounds. The Class P-5A locomotives were very fast for their time and became the standard main line passenger locomotive, but they also did well in freight service.

Needing more motive power the ACL and the Baldwin mechanical engineers designed a dual purpose "Pacific" to take over freight service. Between 1922 and 1926 Baldwin built 165 of these main line locomotives. They were designated as Class P-5B and assigned road numbers 1600 through 1764. The Class P-5A locomotives had 25x28 cylinders, 69" drivers, a 210 psi boiler pressure, exerted 45,275 lbs of tractive effort and each weighed bout 285,000 pounds.

Classes AJ-1 and AJ-2 "The Newcomers"

In 1946, the ACL received 13 "Pacific" type locomotives when it merger one of its holdings, the Atlanta, Biringham & Coast Railroad into its operations. The AB&C had a fleet of locomotives that were mostly purchased second-hand from other railroads. Eleven of these locomotives were originally owned by the Florida East Coast Railroad and were built by The American Locomotive Company. On the ACL they were designated as Class AJ-1 and given road numbers in the 7000 series. Another two, former Great Northern Railroad and Lima Locomotive Works built locomotives, were deignated as Class AJ-2 on the ACL and assigned road numbers 7153 and 7175.

Number 1504 - Class P-5A Survivor

All of the ACL "Pacifics" were retired and scrapped in the early 1950s except for Number 1504. This locomotive was placed on exhibit at the Convention Center in Jacksonville, FL where it can be seen today.

Roster by Richard Duley

ClassQty.Road NumbersYear BuiltBuilderNotes
J3287-2891893Rhode Island These locomotive were given road numbers 287-289 when first received on the ACL. They were rebuilt with a 4-6-0 wheel arrangement in 1912 and given road numbers 1287-1289.
AJ-1117071-7075, 7077 and 7080-70841911-12ALCO These locomotives were added to the ACL roster after the ACL merged with the Atlanta, Birmingham & Coast. The AB&C (see below) bought them used from the Florida East Coast Railway.
AJ-227153 & 71751914Lima These locomotives were added to the ACL roster after the ACL merged with the Atlanta, Birmingham & Coast. The AB&C (see below) bought them used from the Great Northern Railway.

Class Details by Steve Llanso

Class P (Locobase 7673)

Data from ACL 4 - 1942 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection. Works numbers were 36866-36869, 36877-36880, 36893-36896, 36960-36962 in September 1911.

These were the first ACL Pacifics and the last to be delivered with saturated boilers (The first 10 used Walschaert radial valve gear while the last 5 had Baker gear (by Pilliod). Later ACL 4-6-2s had shorter boiler tubes.

Some were later superheated; see Locobase 7674.

Class P - superheated (Locobase 7674)

Data from ACL 4 - 1942 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

When compared to the superheated P-1-S delivered a year later (Locobase 7681), the pressure vessel in the only set of Pacifics it had purchased with saturated boilers (Locobase 7673) was quite a bit larger. As a result, superheating the design actually added overall heating surface area to the boiler. Moreover, unlike many retrofits that took the opportunity of superheating to reduce boiler pressure, the ACL maintained its P-class engines at their original settings. The result was a powerful express passenger engine.

Class P-1 (Locobase 7681)

Data from DeGolyer, Volume 41, p. 236. Works numbers were 38240-38245, 38335-38338, 38349-38350 in September 1912.

P-1s were delivered by Baldwin with superheaters, becoming the first of the line's Pacifics to have that valuable addition, and 14" diameter piston valves. Arch tubes contributed 29.9 sq ft (2.78 sq m) to the firebox heating surface.

They were passenger engines as opposed to the mixed-traffic 4-6-2s the ACL would soon purchase. Although some of the grades briefly pitched up at 6%, maximum main-line curvature was no more than 3 degrees and the rails weighed in at a relatively hefty 85 lb/yard (42.5 kg/metre).

Most of the class was scrapped in November 1939. Only 3 were scrapped after 7 December 1941, the last to go being the class leader 275 in December 1944.

Class P-2 (Locobase 7669)

Data from ACL 12 - 1954 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection. Works numbers were 40119-40129 in July 1913.

This was the third class of Pacifics to run on the ACL and the variant designed to work freight trains. As with most other such designs, the ACL found them less satisfactory than other arrangements. A good factor of adhesion and a relatively large boiler probably accounted for their surviving to the end of steam.

Class P-3 (Locobase 7670)

Data from ACL 12 - 1954 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection. See also DeGolyer, Vol 51, pp. 195+ and Vol 59, pp. 29. Works numbers were


March 41252-41258, 41274-41291


November 42652-42657, 42667-42670


October 44260-44264, 44308-44312

Taking the grate of the P-2 (Locobase 7669) as is, and trimming the boiler tubes and flues by two feet (making room for a combustion chamber whose 34 sq ft (3.16 sq m) contributed to the direct heating surface), reducing the size of the firebox slightly but retaining the 30 sq ft (2.79 sq m) of arch tubes and including , then carrying it on 69" drivers, Baldwin came up with a successful mixed-traffic Pacific that served throughout the system. The firebox also had five 2" "combustion tubes" in each side of the firebox under the brick arch

Like the P-2s, the P-3s had relatively generous 14"-diameter piston valves.

Except for 416 (November 1947), 451-452 (May 1949), 415 (October 1949) and class leader 411 (which exploded February 1950), the class went to the scrapyards in the early 1950s.

Class P-4 (Locobase 7672)

Data from ACL 12 - 1954 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection. See also DeGolyer, Vol 59, pp. 42+. Works numbers were


August 46065, 46111, 46128, 46169; September 46273-46274


January 47730-47731, 47798-47799; February 47864-47865, 47918-47919, 47963; March 48076, 48145; April 48267, 48402; June 48905-48906, 48993, 49074; July 49232-49233, 49302.

P-4s were enlarged P-3s (Locobase 7670) with more tubes and flues, a larger grate, and greater cylinder volume due to a 1" (25.4 mm) increase in diameter. Baldwin delivered seven in 1917 and the other twenty in 1918.

Like the earlier ACL Atlantics, this class had relatively generous 14" (356 mm) diameter piston valves. The last 8 -- 475-482 -- had 18-ft 2-in (5.54 m) tubes that reduced heating surface areas slightly. Firebox heating surface included 36 sq ft (3.35 sq m) of combustion chamber and 30 sq ft (2.8 sq m) of "firebrick tubes".

Like most of the ACL's Pacifics, this class served the railroad for over 3 decades. The first two to be scrapped -- 464 and 471 -- went in October 1949. Disposals continued over the next two-and-a-half years and culminated in a final block of 11 in March 1952.

Class P-5-A (Locobase 1417)

Data from 1946 ACL locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

This was the "light" Pacific design standardized by the government-run USRA created in World War I and built by Baldwin and Alco. Alco-Brooks and Alco-Richmond delivered these to the ACL.

Slightly modified versions were built as the P-5-B, which see.

Class P-5-B (Locobase 448)

Data from DeGolyer, Vol 68, pp. 181+ and Vol 75, pp. 1+. See also ACL 3 - 1946 Locomotive Diagrams supplied in May 2005 by Allen Stanley.

Works numbers were:


July 55576-55577

September 55627-55631

October 55754-55756

November 55707-55716


January 56132-56134

March 56292-56304, 56374-56377

April 56378, 56404-56406, 56453

October 57367-57369

November 57425-57428, 57438, 57443-57444, 57492-57506


June 57813-57814, 57843-57849, 58492-58494, 58498

July 57878-57884, 57902-57905


June 58484-58485

July 58516-58527, 58564-58566

August 58576-58583

September 58641-58643

October 58770-58777

November 58819-58823

December 58886-58895


January 58931-58935, 58977-58991

Firebox had combustion chamber contributing 44 sq ft (4.1 sq m) of heating surface and a 27 sq ft (2.5 sq m). Almost identical to USRA light Pacific design except for smaller driving wheels and slightly less tube and flue area. Fourteen-inch (356 mm) piston valves supplied the cylinders with steam. Also fitted with Ragonnet power reverse gear.

165 built by Baldwin in 1922-1926 as dual-service locomotives. J Parker Lamb (in Perfecting the American Steam Locomotive, 2003) says that this dual-purpose use was unique among US Pacific operators. The reason lies with the ACL's type of freight traffic -- typically lightweight agricultural products. Like the New York Central, moreover, much of the ACL consisted of water-level running.

Retired in 1950-1953.

Specifications by Steve Llanso
ClassPP - superheatedP-1P-2P-3P-4P-5-AP-5-B
Locobase ID7673 7674 7681 7669 7670 7672 1417 448
RailroadAtlantic Coast Line (ACL)Atlantic Coast Line (ACL)Atlantic Coast Line (ACL)Atlantic Coast Line (ACL)Atlantic Coast Line (ACL)Atlantic Coast Line (ACL)Atlantic Coast Line (ACL)Atlantic Coast Line (ACL)
Road Numbers260-274260-274275-286287-297 / 400-411411-455456-4821500-15691600-1764
Valve GearBaker or WalschaertBaker or WalschaertWalschaertWalschaertWalschaertWalschaertBakerBaker
Locomotive Length and Weight
Driver Wheelbase13'13'13'13'13'13'13'13'
Engine Wheelbase33'33'33'33'33'33'34.92'34.91'
Ratio of driving wheelbase to overall engine wheebase 0.39 0.39 0.39 0.39 0.39 0.39 0.37 0.37
Overall Wheelbase (engine & tender)67.56'67.56'67.65'67.48'67.48'67.19'70.79'70.82'
Axle Loading (Maximum Weight per Axle)48200 lbs48200 lbs48100 lbs48700 lbs52600 lbs58200 lbs59060 lbs
Weight on Drivers138950 lbs138950 lbs138000 lbs145000 lbs139400 lbs151050 lbs168000 lbs177460 lbs
Engine Weight220850 lbs220850 lbs224000 lbs225900 lbs227300 lbs243850 lbs278000 lbs280610 lbs
Tender Light Weight159800 lbs159800 lbs160000 lbs159800 lbs166220 lbs166220 lbs188000 lbs188000 lbs
Total Engine and Tender Weight380650 lbs380650 lbs384000 lbs385700 lbs393520 lbs410070 lbs466000 lbs468610 lbs
Tender Water Capacity8000 gals8000 gals8000 gals8000 gals8000 gals8000 gals10000 gals10000 gals
Tender Fuel Capacity (oil/coal)15 tons15 tons12 tons12 tons12 tons12 tons16 tons16 tons
Minimum weight of rail (calculated) on which locomotive could run77 lb/yard77 lb/yard77 lb/yard81 lb/yard77 lb/yard84 lb/yard93 lb/yard99 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter72"72"72"64"69"69"73"69"
Boiler Pressure200 psi200 psi200 psi200 psi200 psi200 psi200 psi210 psi
Cylinders (dia x stroke)22" x 28"22" x 28"22" x 28"22" x 28"22" x 28"23" x 28"25" x 28"25" x 28"
Tractive Effort31998 lbs31998 lbs31998 lbs35998 lbs33389 lbs36493 lbs40753 lbs45272 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.34 4.34 4.31 4.03 4.18 4.14 4.12 3.92
Heating Ability
Firebox Area220 sq. ft220 sq. ft229.90 sq. ft229.50 sq. ft248 sq. ft268 sq. ft242 sq. ft273 sq. ft
Grate Area54 sq. ft54 sq. ft54.20 sq. ft54.20 sq. ft54.20 sq. ft56.50 sq. ft66.70 sq. ft66.70 sq. ft
Evaporative Heating Surface3547 sq. ft3005 sq. ft2887 sq. ft2934 sq. ft2649 sq. ft3420 sq. ft3333 sq. ft3191 sq. ft
Superheating Surface660 sq. ft590 sq. ft587 sq. ft524 sq. ft782 sq. ft794 sq. ft794 sq. ft
Combined Heating Surface3547 sq. ft3665 sq. ft3477 sq. ft3521 sq. ft3173 sq. ft4202 sq. ft4127 sq. ft3985 sq. ft
Evaporative Heating Surface/Cylinder Volume287.93243.93234.35238.17215.03254.00209.52200.59
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation1080010800108401084010840113001334014007
Same as above plus superheater percentage1080012744126831268312683134471587516808
Same as above but substitute firebox area for grate area4400051920537975370358032637845759668796
Power L1905319570182091621716066201531788017765
Power MT430.91931.51872.69739.70762.25882.42703.90662.09




Introduction and roster provided by Richard Duley. Class details and specifications provided by Steve Llanso of Sweat House Media.