Allegheny River Mining Company 2-8-2 "Mikado" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class J (Locobase 13794)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University Volume 38, p. 241. Works numbers were 36817-36820 in August 1911.

At the same time the ARMC ordered duplicate Pittsburg, Shawmut & Northern H-4s (which they designated simply H class - Locobase 13793), they bought a pair of elongated Hs with a trailing truck - Mikado Hs, one might call them. Power dimensions were identical, adhesion weight virtually so, the firebox little changed and the grate not at all, but the tube count fell by 31 even as each tube was elongated by 51 inches. The resulting locomotives had very big boilers for their cylinder volume.

201 went to the ferro-knacker before World War II in November 1938. 200 carried on until it was scrapped in August 1950.

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID13794
RailroadAllegheny River Mining Company
Number in Class2
Road Numbers200-201
Number Built2
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)14.50 / 4.42
Engine Wheelbase (ft / m)32.33 / 9.85
Ratio of driving wheelbase to overall engine wheelbase 0.45
Overall Wheelbase (engine & tender) (ft / m)
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)181,000 / 82,100
Engine Weight (lbs / kg)228,000 / 103,419
Tender Loaded Weight (lbs / kg)130,000 / 58,967
Total Engine and Tender Weight (lbs / kg)358,000 / 162,386
Tender Water Capacity (gals / ML)7000 / 26.52
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)14 / 13
Minimum weight of rail (calculated) (lb/yd / kg/m)75 / 37.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)51 / 1295
Boiler Pressure (psi / kPa)200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)22" x 28" / 559x711
Tractive Effort (lbs / kg)45,173 / 20490.15
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.01
Heating Ability
Tubes (number - dia) (in / mm)350 - 2" / 51
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)19 / 5.79
Firebox Area (sq ft / m2)190 / 17.65
Grate Area (sq ft / m2)57 / 5.30
Evaporative Heating Surface (sq ft / m2)3656 / 339.65
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)3656 / 339.65
Evaporative Heating Surface/Cylinder Volume296.75
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation11,400
Same as above plus superheater percentage11,400
Same as above but substitute firebox area for grate area38,000
Power L16356
Power MT309.67

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Wes Barris