Alaska Railroad 4-8-2 "Mountain" Locomotives of the USA

At 268,000 lbs, the Alaska Railroad Mountains were the lightest of the type.

Roster by Richard Duley

CNRoad NumbersYear BuiltBuilder

Class Details by Steve Llanso of Sweat House Media

Class 801 (Locobase 5094)

Data from (visited December 2002)

Firebox had 3 thermic syphons (84 sq ft) and a combustion chamber (64 sq ft), which together contributed 148 sq ft to the firebox heating surface. Small Mountain for this northernmost American railroad. Indeed, it is one of only 3 North American standard gauge 4-8-2s in Locobase with an adhesion weight under 200,000 lb. (The others are the 1914 Canadian Pacific I1 class found in Locobase 4258 and the New Orleans Great Northern 200 at Locobase 6909)

Built in Philadelphia, the engines were taken apart and shipped up to Anchorage, where they were reassembled in the shops. 801 (works number 61736 in May 1932) was completed in 1932. It was wrecked twice, once in 1942 and once in 1950.

802 (works number 64366) entered service on 5 December 1942 and ran until dieselization led to its retirement and scrapping in April 1954.

Specifications by Steve Llanso of Sweat House Media
Locobase ID5094
RailroadAlaska Railroad
Number in Class2
Road Numbers801-802
Number Built2
Valve GearBaker
Locomotive Length and Weight
Driver Wheelbase16.50'
Engine Wheelbase38.50'
Ratio of driving wheelbase to overall engine wheebase 0.43
Overall Wheelbase (engine & tender)73.29'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers190850 lbs
Engine Weight273300 lbs
Tender Light Weight200300 lbs
Total Engine and Tender Weight473600 lbs
Tender Water Capacity10000 gals
Tender Fuel Capacity (oil/coal)14 tons
Minimum weight of rail (calculated)80 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter63"
Boiler Pressure220 psi
Cylinders (dia x stroke)22" x 30"
Tractive Effort43099 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.43
Heating Ability
Firebox Area416 sq. ft
Grate Area62.50 sq. ft
Evaporative Heating Surface2870 sq. ft
Superheating Surface706 sq. ft
Combined Heating Surface3576 sq. ft
Evaporative Heating Surface/Cylinder Volume217.44
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation13750
Same as above plus superheater percentage16500
Same as above but substitute firebox area for grate area109824
Power L119783
Power MT914.10


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