Seboomook Lake & St John 2-6-2 "Prairie" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class 3 (Locobase 15235)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University Volume 71, pp. 366+. See also Robert E Pike, Tall Trees, Tough Men (New York, W W Norton, 1967, paperback 1984, reissued 1999) pp. 163-164. Works number was 56606 in May 1923.

A typical Baldwin logging Mikado, this engine used a saturated boiler, the practically universal 44" drivers, and slide valves. Great Northern Paper Company took eight years (1919-1927) to build this 18 mile (29 km) railroad from the headwaters of the St John River in Maine as a way to move pulpwood down river. Pike comments that there must have been "some question from the beginning about the feasibility of this whole project."

History bears out such skepticism: "Not one stick of pulpwood and not a single log was ever hauled over it, and by 1929, those opposed had won out and the rails were taken up." Trucks over gravel road were by then much more useful.

The 3 was quickly sold to Wisconsin Michigan Lumber which then sold it to Rib Lake Lumber northwest of Wausau, one of the biggest loggers in Wisconsin.

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID15235
RailroadSeboomook Lake & St John
Number in Class1
Road Numbers3
Number Built1
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)10.25 / 3.12
Engine Wheelbase (ft / m)26.83 / 8.18
Ratio of driving wheelbase to overall engine wheelbase 0.38
Overall Wheelbase (engine & tender) (ft / m)46.54 / 14.19
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)92,000 / 41,731
Engine Weight (lbs / kg)121,000 / 54,885
Tender Loaded Weight (lbs / kg)74,000 / 33,566
Total Engine and Tender Weight (lbs / kg)195,000 / 88,451
Tender Water Capacity (gals / ML)3500 / 13.26
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)6 / 6
Minimum weight of rail (calculated) (lb/yd / kg/m)51 / 25.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)44 / 1118
Boiler Pressure (psi / kPa)170 / 11.70
High Pressure Cylinders (dia x stroke) (in / mm)17" x 24" / 432x610
Tractive Effort (lbs / kg)22,778 / 10331.94
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.04
Heating Ability
Tubes (number - dia) (in / mm)200 - 2" / 51
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)14.75 / 4.50
Firebox Area (sq ft / m2)101 / 9.38
Grate Area (sq ft / m2)18.90 / 1.76
Evaporative Heating Surface (sq ft / m2)1637 / 152.08
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)1637 / 152.08
Evaporative Heating Surface/Cylinder Volume259.43
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation3213
Same as above plus superheater percentage3213
Same as above but substitute firebox area for grate area17,170
Power L14232
Power MT304.24

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