Mississippi River & Bonne Terre 4-6-2 "Pacific" Locomotives of 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.

Specifications by Steve Llanso of Sweat House Media
Class30 / P-65
Locobase ID14344
RailroadMississippi River & Bonne Terre
Number in Class2
Road Numbers30-31 / 6530-6531
Number Built2
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase12'
Engine Wheelbase30.83'
Ratio of driving wheelbase to overall engine wheebase 0.39
Overall Wheelbase (engine & tender)56.33'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers120000 lbs
Engine Weight189000 lbs
Tender Light Weight100000 lbs
Total Engine and Tender Weight289000 lbs
Tender Water Capacity5000 gals
Tender Fuel Capacity (oil/coal)10 tons
Minimum weight of rail (calculated)67 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter64"
Boiler Pressure190 psi
Cylinders (dia x stroke)21" x 26"
Tractive Effort28934 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.15
Heating Ability
Firebox Area154 sq. ft
Grate Area44.30 sq. ft
Evaporative Heating Surface2417 sq. ft
Superheating Surface558 sq. ft
Combined Heating Surface2975 sq. ft
Evaporative Heating Surface/Cylinder Volume231.89
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation8417
Same as above plus superheater percentage10016
Same as above but substitute firebox area for grate area34819
Power L115962
Power MT879.75

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