St Louis & O'Fallon 2-6-2 "Prairie" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class 7 (Locobase 15302)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University Vol 73, pp. 187+ and Vol 77, pp. 771+. Works number was 57637 in June 1924 and 59760 in January 1927.

Running from Mine #2 (the Black Eagle) to East St Louis about 8.9 miles (14.3 km) away, this railway's coal traffic was bought by Western Anthracite Coal & Coke Company for sale on the St Louis market. Coal was the StL&O'F's major business and proved quite profitable; the railroad also took a lot of transfer traffic. Its ownership by the Adolph Busch brewing family ensured that most of the coal would go straight to the brewery's plant.

This big Prairies were clearly meant for long coal drags, even though other wheel arrangements (2-8-0s, e.g.) were more commonly used. It traveled on 85 lb/yard (42.5 kg/metre) rail. The design's cylinders were supplied steam through 11" (279 mm) piston valves.

The 7 would later operate on the St Louis Terminal Railroad as their 49. The 8 took a more circuitous route, first serving the Manufacturers Railways in St Louis, where it was rebuilt as an 0-6-2, then going to the StLTRR in May 1941 as their 47.

Principal Dimensions by Steve Llanso of Sweat House Media
Locobase ID15,302
RailroadSt Louis & O'Fallon
Number in Class1
Road Numbers7-8
Number Built1
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)11 / 3.35
Engine Wheelbase (ft / m)27.50 / 8.38
Ratio of driving wheelbase to overall engine wheebase 0.40
Overall Wheelbase (engine & tender) (ft / m)56.08 / 17.09
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)147,000 / 66,678
Engine Weight (lbs / kg)195,000 / 88,451
Tender Loaded Weight (lbs / kg)141,000 / 63,957
Total Engine and Tender Weight (lbs / kg)336,000 / 152,408
Tender Water Capacity (gals / ML)7000 / 26.52
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)12 / 10.90
Minimum weight of rail (calculated) (lb/yd / kg/m)82 / 41
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)20" x 26" / 508x660
Tractive Effort (lbs / kg)34,667 / 15724.71
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.24
Heating Ability
Firebox Area (sq ft / m2)174 / 16.16
Grate Area (sq ft / m2)44.70 / 4.15
Evaporative Heating Surface (sq ft / m2)2742 / 254.74
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)2742 / 254.74
Evaporative Heating Surface/Cylinder Volume290.04
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation8940
Same as above plus superheater percentage8940
Same as above but substitute firebox area for grate area34,800
Power L16495
Power MT292.22

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