Duluth, Missabe & Iron Range 2-8-8-4 "Yellowstone" Locomotives of the USA


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Class Details by Steve Llanso of Sweat House Media

Class M-3/M-4 (Locobase 334)

Data from tables and diagrams in 1947 Locomotive Cyclopedia and from DM&IR 6 - 1951 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection. (Thanks to Chris Hohl for correcting valve gear ID.) Works numbers were 62526-62533 in May 1941; 64707-64711 in January 1943 and 64712-64716 in February.

These classic engines were based to a large extent on the Western Pacific's M-137-151 2-8-8-2 engines of 1931 (Locobase 332), but were lengthened to take an all-weather cab . The DM & IR engines burned bituminous coal and had a smaller grate area than the oil-burning M-137s although the overall firebox heating surface grew by 11 sq ft (1 sq m). In the M-4, this total included 194 sq ft (18 sq m) in three thermic syphons, 177 sq ft (16.45 sq m) in the combustion chamber, and 32 sq ft (3 sq m) of arch tubes. As part of the M-137 revision, the combustion chamber's length grew from 6 to 7 feet (2,134 mm).

Boiler tube and flue length (sheet to sheet) was shortened by 2 feet to 21 feet (6.4 m). The mixture of tubes and flues changed as the design substituted a Type E superheater for the M-137's Type A. The number of 2 1/4-in flues decreased to 82 and Baldwin installed 245 of the 3 3/4-in flues (vs. the M-137's 270 of the former and 75 5 1/2-in flues) . As a result, superheater area increased by 25%. The first five M-4s had Worthington feedwater heaters, the last five Elescos. Four piston valves each measured 12" (306 mm) in diameter.

Following contemporary practice, the M-3s had integrally cast frames and cylinders, Timken roller bearings on all driving axles, ASF (M-3) or SKF (M-4) roller bearings on all truck axles.

These engines performed very well from the time they entered service in May 1941, soon handling train loads 25% heavier than the earlier M-1/M-2 engines could manage. The last ten engines were M-4s, built by Baldwin in 1943, which used carbon steel in certain components because of a shortage of high-tech alloy steels. They had an engine weight of 699,700 lb (317,379 kg).

During 1943-44, as many as 12 "Yellowstones" were operating on the D & RGW, the GN, and the NP under lease where they were highly regarded. In fact, the D & RGW telegraphed the DM&IR with the claim that these Yellowstones were the finest engines ever to run on the Rio Grande.

The Lake Superior Railroad Museum site -- http://www.lsrm.org/Museum/mallet.htm (visited 9 Feb 2004) -- gives some interesting consumption numbers: " When working at full power, [the locomotive] could consume some 10 to 12 tons of coal an hour and evaporate water into steam at the astounding rate of 12,000 gallons per hour. The amount of coal ...used in one hour would be enough to heat a home for two winters." (and Minnesota winters at that, one supposes.)

Specifications by Steve Llanso of Sweat House Media
Locobase ID334
RailroadDuluth, Missabe & Iron Range (DM&IR)
Number in Class18
Road Numbers220-237
Number Built18
Valve GearBaker
Locomotive Length and Weight
Driver Wheelbase17.25'
Engine Wheelbase67.17'
Ratio of driving wheelbase to overall engine wheebase 0.26
Overall Wheelbase (engine & tender)113.49'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers560257 lbs
Engine Weight695040 lbs
Tender Light Weight438000 lbs
Total Engine and Tender Weight1133040 lbs
Tender Water Capacity25000 gals
Tender Fuel Capacity (oil/coal)26 tons
Minimum weight of rail (calculated)117 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter63"
Boiler Pressure240 psi
Cylinders (dia x stroke)26" x 32"
Tractive Effort140093 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.00
Heating Ability
Firebox Area750 sq. ft
Grate Area125 sq. ft
Evaporative Heating Surface6782 sq. ft
Superheating Surface2770 sq. ft
Combined Heating Surface9552 sq. ft
Evaporative Heating Surface/Cylinder Volume172.45
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation30000
Same as above plus superheater percentage38700
Same as above but substitute firebox area for grate area232200
Power L122723
Power MT715.32



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