Minneapolis, Sault Ste Marie & Atlantic 0-6-6 Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class H/B (Locobase 16490)

Data from Soo 9 - 1930 Steam Locomotive Diagrams supplied in May 2005 and August 2013 by Allen Stanley from his extensive Rail Data Exchange. Stanley later added Soo 3-1909 Classification of Locomotives in August 2013. (Thanks to Chris Hohl for his 13 Auguat 2020 email noting the Soo's preference for "renumbered", a later change in driver diameter, and the reductions in fuel and water capacities when the 325 reverted to a tank locomotive layout.) Rhode Island works number was 1877.

Like the 0-4-6T locomotive built for the same railroad at the same time (1887), this engine merited inclusion nevertheless because it was based on Matthias Forney's tank locomotive design. Compared to the smaller four-coupled Y, the H used more boiler, but less firebox and grate. At some later date, the drivers were fitted with thicker tires that increased diameter to 50" (1,270 mm).

In October 1927, the Soo's shops removed the H's bunker and tank in favor of a separate tender carrying 2,300 US gallons (8,705 litres) of water and 5 tons (4.5 metric tons) of coal. The tender weighed 53,100 lb (24,086 kg) loaded. It was placed with four other Ocean State-built 0-6-0s in class B.

But in June 1932, the Soo switched back to a tank locomotive layout and renumbered the 321 as class X-90. Chris Hohl pointed out that the reconfigured engine now carried 1,167 US gallons (4,417 litres) and 2.7 tons (2.5 metric tons.

In 1963, 76 years after it entered service on the MSSM&A, the X-90 was retired from the Soo, only to be sold to the Miller Compressing Company.

Principal Dimensions by Steve Llanso of Middle Run Media

Locobase ID16490
RailroadMinneapolis, Sault Ste Marie & Atlantic (Soo)
Number in Class1
Road Numbers38/321
Number Built1
BuilderRhode Island
Valve GearStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m)10 / 3.05
Engine Wheelbase (ft / m)
Ratio of driving wheelbase to overall engine wheelbase
Overall Wheelbase (engine & tender) (ft / m)
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)90,700 / 41,141
Engine Weight (lbs / kg)
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)
Tender Water Capacity (gals / ML)1900 / 7.20
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)4 / 4
Minimum weight of rail (calculated) (lb/yd / kg/m)50 / 25
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)49 / 1245
Boiler Pressure (psi / kPa)160 / 11
High Pressure Cylinders (dia x stroke) (in / mm)18" x 24" / 457x610
Tractive Effort (lbs / kg)21,582 / 9789.44
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.20
Heating Ability
Tubes (number - dia) (in / mm)174 - 2" / 51
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)13.50 / 4.11
Firebox Area (sq ft / m2)65.30 / 6.07
Grate Area (sq ft / m2)15.69 / 1.46
Evaporative Heating Surface (sq ft / m2)1296 / 120.40
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)1296 / 120.40
Evaporative Heating Surface/Cylinder Volume183.31
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation2510
Same as above plus superheater percentage2510
Same as above but substitute firebox area for grate area10,448
Power L12999
Power MT218.69

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