Anderson & Middleton Lumber Company 2-6-2 "Prairie" Locomotives of the USA

Class Details by Steve Llanso of Sweat House Media

Class 1 (Locobase 11731)

Data from Negative 9426, Southern Methodist University, Central University Libraries, DeGolyer Library collection of digitized Baldwin images, retrieved 26 October 2010 from,76. See also DeGolyer, Vol 73, pp. 381+. Works number was 58206 in February 1925. For more on the complicated series of name changes and ownerships, see, last accessed 26 October 2010.

Interesting loggin Prairie tank produced relatively late in the day. Oil-fired, superheated with a good-sized firebox, short driving wheelbase, but relatively long engine wheelbase. A note in the specs said that given the "condition of the rails, it is desirable to keep weight down as much as possible." The boiler delivered steam to the cylinders through 8" (203 mm) piston valves. To compensate for the extreme inclines, the crown sheet was to have a slope consistent with operating the engine on 8% grades. Line curvatures could reach 50 degrees.

The OP & E first appeared as the Oregon & Southeastern in 1904, but was reorganized in 1914 when the OP & E bought the O & S assets. Three years after it was delivered to the A & M LC, the 1acquired the Oregon, Pacific & Eastern herald, which it bore until its retirement in 1959 as a static display.

Specifications by Steve Llanso of Sweat House Media
Locobase ID11731
RailroadAnderson & Middleton Lumber Company
Number in Class1
Road Numbers1
Number Built1
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase10'
Engine Wheelbase26.50'
Ratio of driving wheelbase to overall engine wheebase 0.38
Overall Wheelbase (engine & tender)26.50'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers94360 lbs
Engine Weight126860 lbs
Tender Light Weight
Total Engine and Tender Weight126860 lbs
Tender Water Capacity1600 gals
Tender Fuel Capacity (oil/coal)800 gals
Minimum weight of rail (calculated)52 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter44"
Boiler Pressure165 psi
Cylinders (dia x stroke)17" x 24"
Tractive Effort22109 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.27
Heating Ability
Firebox Area82 sq. ft
Grate Area14.40 sq. ft
Evaporative Heating Surface864 sq. ft
Superheating Surface196 sq. ft
Combined Heating Surface1060 sq. ft
Evaporative Heating Surface/Cylinder Volume137.03
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation2376
Same as above plus superheater percentage2804
Same as above but substitute firebox area for grate area15965
Power L15830
Power MT408.64

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