Montana, Wyoming & Southern 2-8-0 "Consolidation" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class 10 (Locobase 14952)

Data from DeGolyer, Vol 59, pp. 194+ and Vol 77, pp. 796+. See also Jon Axline, "Something of a Nusiance Value: The Montana, Wyoming & Southern Railroad", Montana: The Magazine of Western History (Winter 1999), pp. 48-63 at []. Works numbers were 54486 in January 1921 and 59778 in January 1927.

The 20-mile (32 km) Yellowstone Park Railroad was built by Samuel Hauser to exploit the Clark's Fork coal reserves. It was constructed in 1905-1906 on little or no ballast and used 60 lb/yard (30 kg/metre) relay (already used) rail. Its "professional although not always ethical promoter" Frank Hall did complete the short line that included Bridger, Belfry and Bear Creek before waging a war against the bond holders that led them buying him out in 1909 and renaming the railroad.

Even after the change of management, the MW&S was scored for its "bad service, the poor condition of its line, and its abysmal maintenance program." In a 1912 complaint, the track bed was characterized as being "in fierce condition." Only the employment of William Harry Bunney as general manager in 1918 led to substantial improvement.

It was at that time that the road ordered this medium-sized Consolidation from Eddystone. The specs cited 56 lb/yard (28 kg) rail, 4% and 5% grades, and 14 degree curves (radii of 269 feet/82 metres) as challenges to the locomotive. Superheated steam was admitted to the cylinders through relatively large 12" (305 mm) piston valves.

A sister joined the 10 six years later. A significant change concerned ergonomics. The MW&S found in practice that the only way for the engineer to see out the window when switching was to bend over. The 12 was fitted with the #20's cab design (see Locobase 15304 for the 20), which allowed the engineer to remain standard while looking out the window.

Nevertheless, the railroad's enduring value to the area as the MW&S kept it in business for nearly 50 years. As Jon Axline puts it, the railroad "had a profound impact on how south central Montana developed."

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID14952
RailroadMontana, Wyoming & Southern
Number in Class2
Road Numbers10, 12
Number Built2
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)16 / 4.88
Engine Wheelbase (ft / m)24.50 / 7.47
Ratio of driving wheelbase to overall engine wheelbase 0.65
Overall Wheelbase (engine & tender) (ft / m)57.50 / 17.53
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)154,000 / 69,853
Engine Weight (lbs / kg)175,000 / 79,379
Tender Loaded Weight (lbs / kg)141,000 / 63,957
Total Engine and Tender Weight (lbs / kg)316,000 / 143,336
Tender Water Capacity (gals / ML)7000 / 26.52
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)12 / 11
Minimum weight of rail (calculated) (lb/yd / kg/m)64 / 32
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)54 / 1372
Boiler Pressure (psi / kPa)190 / 13.10
High Pressure Cylinders (dia x stroke) (in / mm)21" x 28" / 533x711
Tractive Effort (lbs / kg)36,930 / 16751.19
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.17
Heating Ability
Tubes (number - dia) (in / mm)162 - 2" / 51
Flues (number - dia) (in / mm)26 - 5.375" / 137
Flue/Tube length (ft / m)13.75 / 4.19
Firebox Area (sq ft / m2)137 / 12.73
Grate Area (sq ft / m2)40 / 3.72
Evaporative Heating Surface (sq ft / m2)1837 / 170.66
Superheating Surface (sq ft / m2)366 / 34
Combined Heating Surface (sq ft / m2)2203 / 204.66
Evaporative Heating Surface/Cylinder Volume163.73
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation7600
Same as above plus superheater percentage8892
Same as above but substitute firebox area for grate area30,455
Power L18864
Power MT507.58

  • MWS 10 (Yesteryear Depot 1930s photo by Paul Eilenburger)
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Wes Barris