Duluth, Missabe & Northern 2-8-8-2 "Chesapeake" Locomotives in the USA

Class M (Locobase 317)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University, Volume 35, p. 166. See also tables in 1930 Locomotive Cyclopedia. (Thanks to Chris Hohl for pointing out the tender capacity.) Works numbers were 35165-35172 in September 1910.

Eight Mallet compounds virtually identical with Virginian 600. The Minnesotans were fitted with a feedwater heater in the boiler that contained 1,694 sq ft (157.38 sq m) of heating surface area, another 160 sq ft (14.86 sq m) was held in a preheater in the steam circuit between the HP and LP cylinders. The Missabe included those areas in its calculation of evaporative heating surface.

The Baldwin specs guaranteed an M to "pull or push" 55 empty steel ore cars weighing 16 tons each and a 10-ton caboose up the 6-mile long (10-km) 2.2% ruling grade from the Duluth docks to Proctor at an average speed of 12 mph (19.3 kph). 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.

Even with their limitations, these workhorse engines were later given Schmidt superheaters, Standard mechanical stokers (in 1925), and Elesco feedwater heaters (in 1930); see Locobase 6653.

This octet was followed by four more engines fitted with superheaters from the start; see Locobase 318.

Class M - superheated (Locobase 6653)

Data from 1951 DM & IR locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

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.

Engine 207 received a much more extensive upgrade that included simpling the power system and installing a Type E superheater; see Locobase 16292.

The Ms were retired in 1953.

Class M - superheated (Locobase 16292)

Data from 1951 DM & IR locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

Seven of the M-class compound Mallets (see Locobase 317) were superheated with Schmidt Type A superheaters (Locobase 6653). The last of the original batch of eight received a more radical upgrade centered on a completely revamped boiler. Tube and flue counts nearly reversed with the installation of a Type E superheater as the superheater elements took up the lion's share. Two more HP cylinders with 12" (305 mm) piston valves replaced the two low-pressure cylinders. The firebox received two Nicholson thermic syphons and an Elesco feed water heater was mounted on the smokebox top.

Although it now had much more in common with the M-2s, the 207 was nevertheless retired with the earlier MS class in 1953.

Class M-1/M-2 (Locobase 318)

Data from DeGolyer, Vol 55, pp. 163. Works numbers were 43530-43531 in June 1916, 45769-45793 in June 1917.

Firebox fitted with arch tubes, which contributed a considerable 48 sq ft (4.5 sq m) to the heating surface total and large combustion chamber which added 108 sq ft (10 sq m). Fifteen-inch (381 mm) piston valves supplied steam to the cylinders.

Four Mallet compounds that followed the eight bought in 1910 (Locobase 317). They pulled empty ore trains up the ruling grade of 2.2% from the ore docks at Duluth and the Proctor yards and brought loaded cars back down; they weren't turned at either end. Of the seven miles of line, six followed the grade while winding around compensated curves of 6-10 percent.

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 Locobases 319, 16290, and .6653.

Class M-2-S (Locobase 16290)

Data is for 208-209, rebuilt in 1931 and 1937, respectively, and is from the 1951 DM & IR locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange..

All of the rebuilds of the original M-2 compound articulateds (Locobase 317) used 12" (305 mm) piston valves on all four cylinders. The 210 had Nicholson thermic syphons adding enough heating surface area to the firebox and combustion chamber to increase direct heating surface area to 417 sq ft (38.65 sq m), a Coffin feed water heater 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.

Class M-2-S (Locobase 16291)

Data is for 208-209, rebuilt in 1931 and 1937, respectively, and is from the 1951 DM & IR locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange..

All of the rebuilds of the original M-2 compound articulateds (Locobase 317) used 12" (305 mm) piston valves on all four cylinders. The 211 was most similar to the 210, but had more 2 1/4" tubes than any of the others, Nicholson thermic syphons added enough heating surface area to the firebox and combustion chamber to increase direct heating surface area to 417 sq ft (38.65 sq m). 211 used a Elesco feed water heater, the third different manufacturer to equip the four locomotives.'

The 207 (class MS) was rebuilt along similar lines in 1931, but came out heavier at 444,650 lb on the drivers.

Class MS (Locobase 319)

Data is for 208-209, rebuilt in 1931 and 1937, respectively, and is from the 1951 DM & IR locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange..

All of the rebuilds of the original M-2-S compound articulateds (Locobase 317) used 12" (305 mm) piston valves on all four cylinders. 208-209 had Worthington Type 5 S feed water heaters and included American Arch security circulators in the firebox. Each tube and flue was 6" longer than those in the 210 rebuild (Locobase 16290).