Anderson & Middleton Lumber Company 2-6-2 "Prairie" Locomotives in 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.

Principal Dimensions 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 Wheelbase (ft / m)10 / 3.05
Engine Wheelbase (ft / m)26.50 / 8.08
Ratio of driving wheelbase to overall engine wheelbase 0.38
Overall Wheelbase (engine & tender) (ft / m)26.50 / 8.08
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)94,360 / 42,801
Engine Weight (lbs / kg)126,860 / 57,543
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)126,860
Tender Water Capacity (gals / ML)1600 / 6.06
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)800 / 3028
Minimum weight of rail (calculated) (lb/yd / kg/m)52 / 26
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)44 / 1118
Boiler Pressure (psi / kPa)165 / 11.40
High Pressure Cylinders (dia x stroke) (in / mm)17" x 24" / 432x610
Tractive Effort (lbs / kg)22,109 / 10028.49
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.27
Heating Ability
Tubes (number - dia) (in / mm)76 - 2" / 51
Flues (number - dia) (in / mm)13 - 5.375" / 137
Flue/Tube length (ft / m)13.54 / 4.13
Firebox Area (sq ft / m2)82 / 7.62
Grate Area (sq ft / m2)14.40 / 1.34
Evaporative Heating Surface (sq ft / m2)864 / 80.30
Superheating Surface (sq ft / m2)196 / 18.22
Combined Heating Surface (sq ft / m2)1060 / 98.52
Evaporative Heating Surface/Cylinder Volume136.93
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 area15,965
Power L15826
Power MT408.35

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