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.
|Class||Qty.||Road Numbers||Year Built||Builder||Notes|
|J||3||287-289||1893||Rhode 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-1||11||7071-7075, 7077 and 7080-7084||1911-12||ALCO||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-2||2||7153 & 7175||1914||Lima||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.|
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.
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.
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.
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.
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.
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.
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.
Works numbers were:
March 56292-56304, 56374-56377
April 56378, 56404-56406, 56453
November 57425-57428, 57438, 57443-57444, 57492-57506
June 57813-57814, 57843-57849, 58492-58494, 58498
July 57878-57884, 57902-57905
July 58516-58527, 58564-58566
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|
|Class||P||P - superheated||P-1||P-2||P-3||P-4||P-5-A||P-5-B|
|Railroad||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)||Atlantic Coast Line (ACL)|
|Road Numbers||260-274||260-274||275-286||287-297 / 400-411||411-455||456-482||1500-1569||1600-1764|
|Valve Gear||Baker or Walschaert||Baker or Walschaert||Walschaert||Walschaert||Walschaert||Walschaert||Baker||Baker|
|Locomotive Length and Weight|
|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 lbs||48200 lbs||48100 lbs||48700 lbs||52600 lbs||58200 lbs||59060 lbs|
|Weight on Drivers||138950 lbs||138950 lbs||138000 lbs||145000 lbs||139400 lbs||151050 lbs||168000 lbs||177460 lbs|
|Engine Weight||220850 lbs||220850 lbs||224000 lbs||225900 lbs||227300 lbs||243850 lbs||278000 lbs||280610 lbs|
|Tender Light Weight||159800 lbs||159800 lbs||160000 lbs||159800 lbs||166220 lbs||166220 lbs||188000 lbs||188000 lbs|
|Total Engine and Tender Weight||380650 lbs||380650 lbs||384000 lbs||385700 lbs||393520 lbs||410070 lbs||466000 lbs||468610 lbs|
|Tender Water Capacity||8000 gals||8000 gals||8000 gals||8000 gals||8000 gals||8000 gals||10000 gals||10000 gals|
|Tender Fuel Capacity (oil/coal)||15 tons||15 tons||12 tons||12 tons||12 tons||12 tons||16 tons||16 tons|
|Minimum weight of rail (calculated) on which locomotive could run||77 lb/yard||77 lb/yard||77 lb/yard||81 lb/yard||77 lb/yard||84 lb/yard||93 lb/yard||99 lb/yard|
|Geometry Relating to Tractive Effort|
|Boiler Pressure||200 psi||200 psi||200 psi||200 psi||200 psi||200 psi||200 psi||210 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 Effort||31998 lbs||31998 lbs||31998 lbs||35998 lbs||33389 lbs||36493 lbs||40753 lbs||45272 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|
|Firebox Area||220 sq. ft||220 sq. ft||229.90 sq. ft||229.50 sq. ft||248 sq. ft||268 sq. ft||242 sq. ft||273 sq. ft|
|Grate Area||54 sq. ft||54 sq. ft||54.20 sq. ft||54.20 sq. ft||54.20 sq. ft||56.50 sq. ft||66.70 sq. ft||66.70 sq. ft|
|Evaporative Heating Surface||3547 sq. ft||3005 sq. ft||2887 sq. ft||2934 sq. ft||2649 sq. ft||3420 sq. ft||3333 sq. ft||3191 sq. ft|
|Superheating Surface||660 sq. ft||590 sq. ft||587 sq. ft||524 sq. ft||782 sq. ft||794 sq. ft||794 sq. ft|
|Combined Heating Surface||3547 sq. ft||3665 sq. ft||3477 sq. ft||3521 sq. ft||3173 sq. ft||4202 sq. ft||4127 sq. ft||3985 sq. ft|
|Evaporative Heating Surface/Cylinder Volume||287.93||243.93||234.35||238.17||215.03||254.00||209.52||200.59|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||10800||10800||10840||10840||10840||11300||13340||14007|
|Same as above plus superheater percentage||10800||12744||12683||12683||12683||13447||15875||16808|
|Same as above but substitute firebox area for grate area||44000||51920||53797||53703||58032||63784||57596||68796|