Eight Mallet compounds virtually identical with Virginian 600. Stoking these engines was sometimes a problem even when two firemen were used. Although capable of handling 85 empties on the steep grades when fitted with mechanical stokers, the smallish boilers restricted their speed when so engaged.
Workhorse engines that were later given Schmidt superheaters, Standard mechanical stokers (in 1925), and Elesco feedwater heaters (in 1930). These engines were followed by 4 more engines fitted with superheaters from the start.
When the M-class Mallets (see Locobase 317) were fitted with Schmidt superheaters, Standard mechanical stokers (in 1925), and Elesco feedwater heaters (in 1930), the result was as is shown here. The firebox heating surface now included thermic syphons.
Four Mallet compounds that followed the 8 bought in 1910 (see record # 317). One source says that 208-209 had 77-sq ft grate area, which is smaller than earlier engines and presumably was still harder to fire and that 210-211 reverted to the early 84-sq ft grate, yielding a GDF of 61,750 and a CHS/GA ratio of 78.02. The data comes from a January 1917 table in Railway Mechanical Engineer for "208" that uses the 84-sq-ft figure.
Frank A King, writing in the November 1980 Trains, confirms the 84-sq-ft figure and notes that overall length was 5 feet less because the firebox was moved 5 ft farther forward.
All were converted to simple expansion locomotives in the 1930s. (see record # 319).
210 (class M-2S) was rebuilt in 1929 with virtually identical specs except for an EHS of 5,441 sq ft and CHS of 7,921 (SHS% of CHS 31.31, BDF 792, CHS/GA ratio 94.3). She was nicknamed Madame Queen.
211 was rebuilt in 1931 and had an EHS of 5621 sq ft and a CHS of 8101 sq ft (SHS% of CHS 30.61, BDF 774, CHS/GA ratio 96.44).
The 207 (class MS) was rebuilt along similar lines in 1931, but came out heavier at 444,650 lb on the drivers.
| Specifications | ||||
|---|---|---|---|---|
| Class | M | M - superheated | M-1/M-2 | MS/etc |
| Locobase ID | 317 | 6653 | 318 | 319 |
| Railroad | Duluth, Missabe & Iron Range (DM&IR) | Duluth, Missabe & Iron Range (DM&IR) | Duluth, Missabe & Iron Range (DM&IR) | Duluth, Missabe & Iron Range (DM&IR) |
| Whyte | 2-8-8-2 | 2-8-8-2 | 2-8-8-2 | 2-8-8-2 |
| Road Numbers | 200-207 | 200-206 | 207-210 | 208-209 |
| Gauge | Std | Std | Std | Std |
| Builder | Baldwin | Baldwin | Baldwin | DM & IR |
| Year | 1910 | 1925 | 1916 | 1929 |
| Valve Gear | Walschaert | Walschaert | Walschaert | Walschaert |
| Locomotive Length and Weight | ||||
| Driver Wheelbase | 40.25' | 15' | 40.25' | 15' |
| Engine Wheelbase | 55.75' | 58.17' | 55.75' | 55.33' |
| Ratio of driving wheelbase to overall engine wheebase | 0.72 | 0.26 | 0.72 | 0.27 |
| Overall Wheelbase (engine & tender) | 83.54' | 87' | 83.54' | 83.83' |
| Axle Loading (Maximum Weight per Axle) | ||||
| Weight on Drivers | 406600 lbs | 392200 lbs | 415200 lbs | 421100 lbs |
| Engine Weight | 448100 lbs | 436000 lbs | 470200 lbs | 494450 lbs |
| Tender Light Weight | 171900 lbs | 171900 lbs | 176800 lbs | 195200 lbs |
| Total Engine and Tender Weight | 620000 lbs | 607900 lbs | 647000 lbs | 689650 lbs |
| Tender Water Capacity | 9000 gals | 9000 gals | 9000 gals | |
| Tender Fuel Capacity (oil/coal) | 16 tons | 16 tons | 21 tons | |
| Minimum weight per yard of rail on which locomotive could run | 84.71 lb rail | 81.71 lb rail | 86.50 lb rail | 87.73 lb rail |
| Geometry Relating to Tractive Effort | ||||
| Driver Diameter | 57" | 57" | 57" | 57" |
| Boiler Pressure | 200 psi | 200 psi | 200 psi | 200 psi |
| Cylinders (dia x stroke) | 26" x 32" | 26" x 32" | 26" x 32" | 24" x 32" (4) |
| Low Pressure Cylinders (dia x stroke) | 40" x 32" | 40" x 32" | 40" x 32" | " x " |
| Tractive Effort | 90709 lbs | 90709 lbs | 90709 lbs | 109945 lbs |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 4.48 | 4.32 | 4.58 | 3.83 |
| Heating Ability | ||||
| Firebox Area | 340 sq. ft | 379 sq. ft | 346 sq. ft | |
| Grate Area | 84 sq. ft | 84 sq. ft | 84 sq. ft | 84 sq. ft |
| Evaporative Heating Surface | 6883 | 4122 | 5424 | 5592 |
| Superheating Surface | 931 | 1168 | 2480 | |
| Combined Heating Surface | 6883 | 5053 | 6592 | 8072 |
| Evaporative Heating Surface/Cylinder Volume | 350.03 | 209.62 | 275.83 | 166.87 |
| Computations Relating to Power Output (More Information) | ||||
| Robert LeMassena's Power Computation | 16800 | 16800 | 16800 | 16800 |
| Same as above plus superheater percentage | 16800 | 19895.35 | 19776.70 | 21961.55 |
| Same as above but substitute firebox area for grate area | 0 | 80528.79 | 89230.58 | 90460.65 |
| Power L1 | 0 | 5797.31 | 7279.19 | 16806.70 |
| Power MT | 0 | 260.70 | 309.21 | 703.92 |
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