These locomotives were designed with 75" drivers, 26 x 32 cylinders, a 270 psi boiler pressure, a weight of 445,550 pounds and had a tractive effort of 66,000 pounds.
There are no survivors.
|Class||Qty||Road Numbers||Locomotive Weight||Year Built||Builder|
Classic Northern from the late 1930s that carried its boiler and firebox on an frame that was integrally cast with both the cylinders and the air reservoirs. Piston valves measured a modest 12" (306 mm) in diameter. The Elesco Type E superheater included a dryer. In place of the commonly adopted feed water heaters, the O-20s used an Elesco Type SL-305 exhaust steam injector.
Drury (1993) says of these engines: "Assigned to fast Chicago-Twin Cities freight trains, [they] acquired a reputation for availability -- they were able to turn at the terminals and be on their way quickly."
NB: The superheater area in the specs is an estimate. It is a calculation based on taking the diagram value of 2,120 sq ft of "superheater equivalent" and deducting a third from it. See the logic presented in Locobase 1364.
|Specifications by Steve Llanso of Sweat House Media|
|Railroad||Minneapolis, St Paul & Sault Ste Marie (Soo)|
|Number in Class||4|
|Locomotive Length and Weight|
|Driver Wheelbase (ft / m)||19.75 / 6.02|
|Engine Wheelbase (ft / m)||46.75 / 14.25|
|Ratio of driving wheelbase to overall engine wheebase||0.42|
|Overall Wheelbase (engine & tender) (ft / m)||87.47 / 26.66|
|Axle Loading (Maximum Weight per Axle) (lbs / kg)||65,900 / 29,892|
|Weight on Drivers (lbs / kg)||263,000 / 119,295|
|Engine Weight (lbs / kg)||445,550 / 202,098|
|Tender Loaded Weight (lbs / kg)||317,600 / 144,061|
|Total Engine and Tender Weight (lbs / kg)||763,150 / 346,159|
|Tender Water Capacity (gals / ML)||17,500 / 66.29|
|Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)||24 / 21.80|
|Minimum weight of rail (calculated) (lb/yd / kg/m)||110 / 55|
|Geometry Relating to Tractive Effort|
|Driver Diameter (in / mm)||75 / 1905|
|Boiler Pressure (psi / kPa)||275 / 19|
|High Pressure Cylinders (dia x stroke) (in / mm)||26" x 32" / 660x813|
|Tractive Effort (lbs / kg)||67,420 / 30581.23|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||3.90|
|Firebox Area (sq ft / m2)||423 / 39.31|
|Grate Area (sq ft / m2)||88.30 / 8.21|
|Evaporative Heating Surface (sq ft / m2)||5142 / 477.88|
|Superheating Surface (sq ft / m2)||1413 / 131.32|
|Combined Heating Surface (sq ft / m2)||6555 / 609.20|
|Evaporative Heating Surface/Cylinder Volume||261.49|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||24,283|
|Same as above plus superheater percentage||29,625|
|Same as above but substitute firebox area for grate area||141,917|