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 Wheelbase (ft)16.50
Engine Wheelbase (ft)38.50
Ratio of driving wheelbase to overall engine wheebase 0.43
Overall Wheelbase (engine & tender) (ft)73.29
Axle Loading (Maximum Weight per Axle) (lbs)
Weight on Drivers (lbs)190,850
Engine Weight (lbs)273,300
Tender Loaded Weight (lbs)200,300
Total Engine and Tender Weight (lbs)473,600
Tender Water Capacity (gals)10,000
Tender Fuel Capacity (oil/coal) (gals/tons)14
Minimum weight of rail (calculated) (lb/yd)80
Geometry Relating to Tractive Effort
Driver Diameter (in)63
Boiler Pressure (psi)220
High Pressure Cylinders (dia x stroke) (in)22" x 30"
Tractive Effort (lbs)43,099
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.43
Heating Ability
Firebox Area (sq ft)416
Grate Area (sq ft)62.50
Evaporative Heating Surface (sq ft)2870
Superheating Surface (sq ft)706
Combined Heating Surface (sq ft)3576
Evaporative Heating Surface/Cylinder Volume217.44
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation13,750
Same as above plus superheater percentage16,500
Same as above but substitute firebox area for grate area109,824
Power L119,783
Power MT914.10


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