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

DM&IR Yellowstone

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
Class M-3/M-4
Locobase ID 334
Railroad Duluth, Missabe & Iron Range (DM&IR)
Country USA
Whyte 2-8-8-4
Road Numbers 220-237
Gauge Std
Builder Baldwin
Year 1941
Valve Gear Baker
Locomotive Length and Weight
Driver Wheelbase 17.25'
Engine Wheelbase 67.17'
Ratio of driving wheelbase to overall engine wheebase 0.26
Overall Wheelbase (engine & tender) 113.49'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers 560257 lbs
Engine Weight 695040 lbs
Tender Light Weight 438000 lbs
Total Engine and Tender Weight 1133040 lbs
Tender Water Capacity 25000 gals
Tender Fuel Capacity (oil/coal) 26 tons
Minimum weight of rail (calculated) 117 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter 63"
Boiler Pressure 240 psi
Cylinders (dia x stroke) 26" x 32"
Tractive Effort 140093 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.00
Heating Ability
Firebox Area 750 sq. ft
Grate Area 125 sq. ft
Evaporative Heating Surface 6782 sq. ft
Superheating Surface 2770 sq. ft
Combined Heating Surface 9552 sq. ft
Evaporative Heating Surface/Cylinder Volume 172.45
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation 30000
Same as above plus superheater percentage 38700
Same as above but substitute firebox area for grate area 232200
Power L1 22723
Power MT 715.32


  • 221 Two Harbors, MN (Yellowstone 221 was displayed for many years near the ore docks in the city of Two Harbors, MN. By the late 1960s, the locomotive was showing signs of severe decay. In 1967, the DM&IR felt it had deteriorated to such a point that warranted its removal and 221 was pulled to the Proctor roundhouse by an SD9 and later sold for scrap. See TRAINS, November 1967 for details.)
  • 224 (On February 7, 1943, a Denver & Salt Lake wrecker comes to grips with front end of Missabe Road 224 at Fireclay, CO after runaway while in Rio Grande employ. Looks pretty rough, doesn't it.)
  • 224
  • 225 Proctor, MN (M-3 225 leads a railfan excursion across a DM&IR trestle near Holman Junction in the late 1950s. Today 225 is on display in Proctor, MN.)
  • 225 on display in Proctor, MN
  • 225 on display in Proctor, MN (Proctor is a few miles west of Duluth and the site of a large railroad yard. In 1995 225 had all of the boiler jacketing removed giving it this "white" appearance. This will probably extend its life on display as moisture will not be trapped against the boiler. Since the time this photo was taken, 225 has been painted and is looking pretty nice.)
  • 225 (2009 Wes Barris photo)
  • 225 (2009 Wes Barris photo showing Baker valve gear)
  • 225 (2009 Wes Barris photo showing Baker valve gear)
  • 225 (Sep 2000 photo courtesy Jeff Terry)
  • 225 (Photo courtesy Wes Barris)
  • 225 (2015 photo coutresy Rod Krotzer)
  • 227 Duluth, MN (Yellowstone 227 was stored at the Proctor roundhouse until 1967. It is now on display inside the Lake Superior Transportation Museum. As a result, it is difficult to get a decent photograph of her. This postcard was taken years ago when she was still outside. Today, her driving wheels are supported slightly above the railheads. An electric motor is used to spin her wheels slowly so that you can see the motion of the massive valve gear. Of the three surviving Yellowstones, 227 is probably in the best shape.)
  • 227 cab interior (Photo courtesy Chris Sanko)
  • 227 cab interior (Photo courtesy Chris Sanko)
  • 227 front (Photo courtesy Chris Sanko)
  • 229 (2015 photo courtesy John Garbutt)
  • 229 Two Harbors, MN
  • 229 Two Harbors, MN (On June 2, 1967, Yellowstone 229 was pulled from the Proctor roundhouse where it had been stored and placed on display in Two Harbors replacing Yellowstone 221 which had deteriorated from exposure to the weather. A small shed was built over 229 to help protect her from the weather.)
  • 229 (1947 Virginia, MN photo courtesy Richard Fink)
  • 229 (Sep 2000 photo courtesy Jeff Terry)
  • 229 (Photo courtesy Timothy Mengler)
  • Yellowstones waiting to be scrapped (Here 232 is shown waiting to be scrapped. A row of centipede tenders detached from their locomotives, yet still full of coal, is on the right. Notice that the first tender belongs to 227 (which is now on display in Duluth). The DM&IR switched the tenders for their steamers around near the end of their careers to keep the best of the equipment in operation. The 227's tender was sent to the Paper Calmenson scrap yard 11-9-62 with steamer 231. 229 has 222's tender, and 227 has 231's tender.)
  • 234 (Number 234 is viewed with a train of 180 cars at Payne, MN on September 30, 1957. Photo courtesy: Walter R. Evans.)
  • Articulated Locomotive Photos


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