Duluth, Missabe & Northern / Duluth & Iron Range 4-6-2 "Pacific" Type Locomotives

Class Details by Steve Llanso

Class A (Locobase 7283)

See data from DM&IR 6 -1951 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection. Works numbers were 39861-39864 in May 1913.

Northern Minnesota didn't have much call for passenger service, but the Iron Range found a need for more power than the Ten-wheelers could provide. They bought these small Pacifics that possessed a free-steaming boiler and 14" piston valves. Locobase doesn't know if the quartet was delivered with superheaters, but if not, the railroad installed them before too long.

All four engines served the D & IR, the DM & N, and the DM & IR on the same rails for 40 years; retirements came in 1953-1955.

See the larger DM & N Pacifics delivered by Baldwin in the same year in Locobase 7284.

Class P (Locobase 7284)

See data from DM&IR 6 -1951 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection. Works numbers were 39877-39879 in May 1913.

In the same time the Duluth & Iron Range took delivery of four light Pacifics (Locobase 7283), the same builder supplied these substantially larger engines to the DM & N.

Whereas the Iron Range's engines were branch-liners, the Northern's trio were headed to the main line. Free-steaming and fitted with 15" piston valves, these 4-6-2s served the DM & N and successor DM & IR into the 1950s before retiring in 1955 (401), 1958 (402), and 400 in 1959.

Specifications by Steve Llanso
Class A P
Locobase ID 7283 7284
Railroad Duluth & Iron Range (DM&IR) Duluth, Missabe & Northern (DM&IR)
Whyte 4-6-2 4-6-2
Road Numbers 107-110 / 1107-1110 400-402
Gauge Std Std
Builder Baldwin Baldwin
Year 1913 1913
Valve Gear Walschaert Walschaert
Locomotive Length and Weight
Driver Wheelbase 12.50' 12.50'
Engine Wheelbase 31.83' 35'
Ratio of driving wheelbase to overall engine wheebase 0.39 0.36
Overall Wheelbase (engine & tender) 63.04' 65.83'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers 140000 lbs 173310 lbs
Engine Weight 223900 lbs 254600 lbs
Tender Light Weight 137400 lbs 171800 lbs
Total Engine and Tender Weight 361300 lbs 426400 lbs
Tender Water Capacity 6300 gals 8600 gals
Tender Fuel Capacity (oil/coal) 14 tons 14 tons
Minimum weight of rail (calculated) on which locomotive could run 78 lb/yard 96 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter 69" 69"
Boiler Pressure 200 psi 200 psi
Cylinders (dia x stroke) 22" x 28" 25" x 28"
Tractive Effort 33389 lbs 43116 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.19 4.02
Heating Ability
Firebox Area 205 sq. ft 243.10 sq. ft
Grate Area 47.70 sq. ft 58.60 sq. ft
Evaporative Heating Surface 2716 sq. ft 3087 sq. ft
Superheating Surface 610 sq. ft 906 sq. ft
Combined Heating Surface 3326 sq. ft 3993 sq. ft
Evaporative Heating Surface/Cylinder Volume 220.47 194.05
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation 9540 11720
Same as above plus superheater percentage 11257 14416
Same as above but substitute firebox area for grate area 48380 59803
Power L1 17234 18010
Power MT 814.17 687.30



Introduction and roster provided by Richard Duley . Class details and specifications provided by Steve Llanso of Sweat House Media.

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