Alaska Railroad / American Railroad 2-8-0 "Consolidation" Locomotives of the USA

Class Details by Steve Llanso of Sweat House Media

Class 21 (Locobase 15360)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University Vol 78, p. 98+. Works numbers were 58798 in October 1925.

Small superheated, oil-burning Consolidation with 8" (203 mm) piston valves and relatively short tubes and flues.

Class 501 (Locobase 6426)

Data from (visited 22 December 2004) and from the US Military Railway Service's Locomotive Diagram book supplied in 2005 by Allen Stanley from his extensive Raildata collection. See also the history of the engines sent to the FC de Langreo by Guillermo Bas Ord=±ez at, last accessed 22 November 2013.

Works numbers are consecutive as were the USATC numbers, but the ARR jumbled them a bit, to wit:


7875 6994 505

7876 6995 506

7877 6996 504

7879 6998 501

7880 6999 502

7881 10 503.

This Consolidation design is bigger than the Standard 160 (Locobase 433) and may have been specially built for the US Army Transportation Corps' operation in Alaska. Its cylinders are larger by 2" in diameter, the grate had 2 sq ft greater area, and the boiler was slightly larger as well.

The MRS diagram shows that the class had 10" (254 mm) diameter piston valves. This diagram states that the tractive effort at 77% was 37,100 lb, which is true only if the driver diameter is 50" - the sketch shows 57". Since the Alaskan site gives 50" as the diameter, the diagram seems to have been in error in that dimension. In addition the driving wheelbase measures 15' 6" (4.72 m) . Clearly, the diagram must be referring to a variant with taller drivers.

Apparently the last locomotive came later, in 1946-1947, possibly as a replacement for 6997? In any case, the 503 was destroyed in a fire in 1951.

Spain's Ferrocarril de Langreo bought several cast-off ARR steam locomotives. Except for ARR 503, this entire class was sold to the FC de L and arrived at Gijon on 25 February 1958 and renumbered 401-406. 401 was kept as a spare, but the other four were quickly found to be too big for the Langreo's loading gauge, wrote , and the railway had to rework the locomotives: "Modifications included cut tender tops, cabs with lowered roofs and slope sides and front pilot substituted by Langreo hook couplings and buffers."

So converted, the locomotives went into service one by one with 404 starting in April 1960 and finishing with 402 ending its mods in March 1963. All ran up service "mileage" (kilometrage?) exceeding 36,700 km each (22,791 miles) with 405 accumulating 38,089 km (23,653 miles). All were withdrawn in 1968 when steam operations ended and were soon scrapped.

Specifications by Steve Llanso of Sweat House Media
Locobase ID15360 6426
RailroadAmerican RailroadAlaska Railroad
Number in Class16
Road Numbers21501-506
Number Built16
Valve GearWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase10.75'14.50'
Engine Wheelbase17.17'23.08'
Ratio of driving wheelbase to overall engine wheebase 0.63 0.63
Overall Wheelbase (engine & tender)46.31'56.74'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers81000 lbs161300 lbs
Engine Weight88500 lbs180000 lbs
Tender Light Weight66500 lbs124700 lbs
Total Engine and Tender Weight155000 lbs304700 lbs
Tender Water Capacity3000 gals6500 gals
Tender Fuel Capacity (oil/coal)1500 gals10 tons
Minimum weight of rail (calculated)34 lb/yard67 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter37"50"
Boiler Pressure160 psi210 psi
Cylinders (dia x stroke)16" x 20"21" x 26"
Tractive Effort18819 lbs40934 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.30 3.94
Heating Ability
Firebox Area95 sq. ft156 sq. ft
Grate Area15 sq. ft43 sq. ft
Evaporative Heating Surface823 sq. ft1937 sq. ft
Superheating Surface155 sq. ft467 sq. ft
Combined Heating Surface978 sq. ft2404 sq. ft
Evaporative Heating Surface/Cylinder Volume176.83185.84
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation24009030
Same as above plus superheater percentage278410746
Same as above but substitute firebox area for grate area1763238984
Power L1570911619
Power MT621.54635.23



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