Alaska Railroad 4-6-2 "Pacific" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class 901 (Locobase 5095)

Locobase doesn't have much information about this Pacific, other than what was supplied on the elevation drawing found on [] . Works numbers were 62515 in December 1940 and 70336 four years later in December 1944.

The Alaska Railroad site -- [] (visited 22 Dec 2004) gives data that suggests this is the 801-series 4-8-2 with one less driving axle and consequently fire tubes that are 18" shorter. Otherwise the two boilers are the same. The firebox heating surface is likely to be virtually identical, although Locobase cannot confirm.

901 & 902 pulled both passenger and freight trains; 902 came in 1945. [] (1 Feb 2004) tells us that even though 901 was one of two locomotives involved in the only head-on collision the road ever had (on 19 October 1943), it carried on until 1952, when it was sold to FC Langreo in Spain but apparently never entered service.

NB: The direct heating surface (including the firebox heating surface) is an estimate calculated by subtracting the calculated tube heating surface from the reported total evaporative heating surface.

Principal Dimensions by Steve Llanso of Sweat House Media
Locobase ID5095
RailroadAlaska Railroad
Number in Class2
Road Numbers901-902
Number Built2
Valve GearBaker
Locomotive Length and Weight
Driver Wheelbase (ft / m)12 / 3.66
Engine Wheelbase (ft / m)34.50 / 10.52
Ratio of driving wheelbase to overall engine wheebase 0.35
Overall Wheelbase (engine & tender) (ft / m)69.29 / 21.12
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)156,200 / 70,851
Engine Weight (lbs / kg)249,000 / 112,945
Tender Loaded Weight (lbs / kg)200,300 / 90,855
Total Engine and Tender Weight (lbs / kg)449,300 / 203,800
Tender Water Capacity (gals / ML)10,000 / 37.88
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)14 / 12.70
Minimum weight of rail (calculated) (lb/yd / kg/m)87 / 43.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)69 / 1753
Boiler Pressure (psi / kPa)200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)22" x 28" / 559x711
Tractive Effort (lbs / kg)33,389 / 15145.01
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.68
Heating Ability
Firebox Area (sq ft / m2)295 / 27.42
Grate Area (sq ft / m2)63 / 5.86
Evaporative Heating Surface (sq ft / m2)2660 / 247.21
Superheating Surface (sq ft / m2)646 / 60.04
Combined Heating Surface (sq ft / m2)3306 / 307.25
Evaporative Heating Surface/Cylinder Volume215.92
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation12,600
Same as above plus superheater percentage15,120
Same as above but substitute firebox area for grate area70,800
Power L118,575
Power MT786.51

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Wes Barris