Mississippi River & Bonne Terre 4-6-2 "Pacific" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class 30 / P-65 (Locobase 14344)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University, Vol 53, pp. 358+. See also the Mississippi-Illinois Railroad at http://moshortline.com/mrbt.html, quoting THE LEAD BELT NEWS, Flat River, St. Francois Co. MO, Fri. June 10, 1938. Works numbers were 44836-44837 in January 1917.

The Lead Belt in eastern Missouri inspired the development of the MR&BT as a narrow-gauge road built between Riverside, 25 miles (40.25 km) below St Louis, and Bonne Terre in 1890. The road was widened to the standard gauge in 1894, but grades never rose beyond 1.8% and the curves were a mild 8 degrees (radii of 717 feet/218.5 metres. The M-I site notes that the line was only 47 miles (75.7 km) long even when it was extended to Doe Run, "but it proved a great factor in the development of the Lead Belt and there was an enormous amount of traffic on the road."

Indeed, rail weights ranged between 75-90 lb/yard (37.5-45 kg/metre), which meant it was "constructed as substantially as most trunk lines." Even so, the order included the caution that: "Engine frames to be extra heavy throughout. Engine frames to be designed to withstand rough usage and considerable lateral thrust, which will be continually in evidence given that the road is all curves, there being only one tangent which is a mile long."

Ultimately, the road included branches dubbed Turpin, Hoffman, Gumbo, and Crawley.

The Missouri Pacific bought the MR&BT in 1929 and incorporated it into the Missouri-Illinois Railroad, which ran it as an independent subsidiary until 1945. The 6530 was scrapped in 1949, but 6531 was sold to Sparta, Illinois's Moffat Coal Company.

Principal Dimensions by Steve Llanso of Sweat House Media
Class30 / P-65
Locobase ID14,344
RailroadMississippi River & Bonne Terre
Number in Class2
Road Numbers30-31 / 6530-6531
Number Built2
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)12 / 3.66
Engine Wheelbase (ft / m)30.83 / 9.40
Ratio of driving wheelbase to overall engine wheebase 0.39
Overall Wheelbase (engine & tender) (ft / m)56.33 / 17.17
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)120,000 / 54,431
Engine Weight (lbs / kg)189,000 / 85,729
Tender Loaded Weight (lbs / kg)100,000 / 45,359
Total Engine and Tender Weight (lbs / kg)289,000 / 131,088
Tender Water Capacity (gals / ML)5000 / 18.94
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)10 / 9.10
Minimum weight of rail (calculated) (lb/yd / kg/m)67 / 33.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)64 / 1626
Boiler Pressure (psi / kPa)190 / 13.10
High Pressure Cylinders (dia x stroke) (in / mm)21" x 26" / 533x660
Tractive Effort (lbs / kg)28,934 / 13124.26
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.15
Heating Ability
Firebox Area (sq ft / m2)154 / 14.31
Grate Area (sq ft / m2)44.30 / 4.12
Evaporative Heating Surface (sq ft / m2)2417 / 224.54
Superheating Surface (sq ft / m2)558 / 51.84
Combined Heating Surface (sq ft / m2)2975 / 276.38
Evaporative Heating Surface/Cylinder Volume231.89
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation8417
Same as above plus superheater percentage10,016
Same as above but substitute firebox area for grate area34,819
Power L115,962
Power MT879.75

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