Minneapolis, St Paul & Sault Ste Marie 2-6-2 "Prairie" Locomotives in the USA


Class Details by Steve Llanso of Sweat House Media

Class J (Locobase 8741)

Data from Soo Miscellaneous Steam Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

Locobase 16533 shows the original cross-compounds delivered in 1907. Both cylinders had 26" strokes; the HP cylinder diameter measured 22", the LP a lusty 35" across.

After their conversions, the class served the Soo for decades. Aside from the 808, which was scrapped in 1940, the Js ran into the late 1940s with the 803 lingering until July 1956.


Class J (Locobase 16533)

Data from "Prairie Compound Locomotive for the Soo Line", Daily Railway Age, Volume XLIII [43], No. 23b (13 June 1907), p. 932-933. Works numbers were 42642-42651 in March 1907.

These were the only Prairies to be bought by the Soo and they were pretty rare birds. They arrived as cross-compounds, which DRA reported had enjoyed considerable success on the railway in both freight and passenger service. Until this purchase, 65 cross-compound Moguls (2-6-0) such as the D-2 (Locobases 11170 and 16376) had hauled fast freights, but were needed more on the passenger trains despite the 8" (203 mm) smaller driver diameter . (Such a change suggests how modest Soo passenger trains were in size and speed.) Placing a trailing truck under the firebox allowed for longer tubes that increased boiler capacity.

Compounded on the Schenectady principle, the high-pressure cylinder sat on the left side and used a 12" (305 mm) piston valve to admit steam. The large low-pressure cylinder was attached to the right side and used Allen-Richardson balanced slide valves. A slight variation in equalizing drivers and trucks had the front and main drivers equalized with the front truck and the rear drivers compensated with the rear truck.

As usual, these two-cylinder compounds soon were converted to simple-expansion engines; see Locobase 8741.

Principal Dimensions by Steve Llanso of Sweat House Media

ClassJJ
Locobase ID8741 16533
RailroadMinneapolis, St Paul & Sault Ste Marie (Soo)Minneapolis, St Paul & Sault Ste Marie (Soo)
CountryUSAUSA
Whyte2-6-22-6-2
Number in Class1010
Road Numbers800-809800-809
GaugeStdStd
Number Built10
BuilderSooAlco-Schenectady
Year1907
Valve GearStephensonStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m)11.33 / 3.4511.33 / 3.45
Engine Wheelbase (ft / m)20.25 / 6.1729.25 / 8.92
Ratio of driving wheelbase to overall engine wheelbase 0.56 0.39
Overall Wheelbase (engine & tender) (ft / m)55.67 / 16.9756 / 17.07
Axle Loading (Maximum Weight per Axle) (lbs / kg)48,760 / 22,117
Weight on Drivers (lbs / kg)132,760 / 60,219133,000 / 60,328
Engine Weight (lbs / kg)181,320 / 82,245191,300 / 86,772
Tender Loaded Weight (lbs / kg)128,810 / 58,427118,000 / 53,524
Total Engine and Tender Weight (lbs / kg)310,130 / 140,672309,300 / 140,296
Tender Water Capacity (gals / ML)6000 / 22.736000 / 22.73
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)10 / 910 / 9
Minimum weight of rail (calculated) (lb/yd / kg/m)74 / 3774 / 37
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)63 / 160063 / 1600
Boiler Pressure (psi / kPa)185 / 12.80200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)22.5" x 26" / 572x66022.5" x 26" / 572x660 (1)
Low Pressure Cylinders (dia x stroke) (in / mm)35" x 26" / 889x660 (1)
Tractive Effort (lbs / kg)32,854 / 14902.3425,132 / 11399.70
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.04 5.29
Heating Ability
Tubes (number - dia) (in / mm)143 - 2" / 51266 - 2" / 51
Flues (number - dia) (in / mm)21 - 5.375" / 137
Flue/Tube length (ft / m)15 / 4.5715 / 4.57
Firebox Area (sq ft / m2)165 / 15.33165 / 15.33
Grate Area (sq ft / m2)38.36 / 3.5738.36 / 3.56
Evaporative Heating Surface (sq ft / m2)1716 / 159.482244 / 208.47
Superheating Surface (sq ft / m2)347 / 32.25
Combined Heating Surface (sq ft / m2)2063 / 191.732244 / 208.47
Evaporative Heating Surface/Cylinder Volume143.36375.01
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation70977672
Same as above plus superheater percentage83037672
Same as above but substitute firebox area for grate area35,71433,000
Power L191924452
Power MT457.93221.39

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