Portland & Southwestern 2-6-2 "Prairie" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class 1 (Locobase 12979)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University Vol 29, p. 112. Works number was 28465 in June 1906.

This Scappoose, Ore timber line was owned by Chapman Lumber. Remarkably for a logging operation, the P & SW bored a tunnel through a mountain west of Chapman to reach the Nehalem Valley stands of timber.

When they bought this Praire, Chapman made sure Baldwin knew the maximum grade was 6% and curve radii could reach 35 degrees. An additional feature of this particular order was the provision of a standard 2" steam line from the locomotive boiler under the tender to a flexible pipe supplied by the company and capable of withstanding the normal working pressure of the boiler. This line supplied a steam engine mounted on a flat car.

The #1 operated on the P & SW for about a decade before being sold to Clark & Wilson Lumber Company of Goble, Oregon.

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID12979
RailroadPortland & Southwestern
Number in Class1
Road Numbers1
Number Built1
BuilderBurnham, Williams & Co
Valve GearStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m) 7.67 / 2.34
Engine Wheelbase (ft / m)23.83 / 7.26
Ratio of driving wheelbase to overall engine wheelbase 0.32
Overall Wheelbase (engine & tender) (ft / m)
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)82,000 / 37,195
Engine Weight (lbs / kg)107,000 / 48,534
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)
Tender Water Capacity (gals / ML)3000 / 11.36
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)1200 / 4542
Minimum weight of rail (calculated) (lb/yd / kg/m)46 / 23
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)44 / 1118
Boiler Pressure (psi / kPa)180 / 12.40
High Pressure Cylinders (dia x stroke) (in / mm)16" x 24" / 406x610
Tractive Effort (lbs / kg)21,364 / 9690.56
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.84
Heating Ability
Tubes (number - dia) (in / mm)240 - 2" / 51
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)11.54 / 3.52
Firebox Area (sq ft / m2)122 / 11.33
Grate Area (sq ft / m2)16 / 1.49
Evaporative Heating Surface (sq ft / m2)1561 / 145.07
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)1561 / 145.07
Evaporative Heating Surface/Cylinder Volume279.25
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation2880
Same as above plus superheater percentage2880
Same as above but substitute firebox area for grate area21,960
Power L15127
Power MT413.53

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