Originally built by Great Northern with relatively tall drivers for a compound articulated. They presented an imposing appearance, showing a high Belpaire boiler over ten axles of running gear. Firebox heating surface included 81 sq ft (7.53 sq m) of combustion chamber All four cylinders were fed through 15" (381 mm) piston valves.
The last eight were oil burners and trailed tenders carrying the same amount of water as the first 17, but holding 4,500 US gallons (17,033 litres) of fuel oil.
The Baldwin specs describe the Emerson "New Type" superheater. The engines were big and superheated and presumably presented some new challenges. So the specs contain some "Hereafter" notes tweaking details. One, however, implied a higher level of urgency. Referring to a letter from F A Neely received on 3 November 1912, the note said "Give particular attention to riveting of cylinder saddles and caulking of same."
"Leaky seams" forced the railroad to remove lagging from all the boilers in the first batch save that of 2016 and caulk them. A least some high-pressure cylinders leaked and the flexible stay bolts at the back end of the combustion chamber either required redesign or at least more stays. (The firebox had 900 Tate flexible staybolts in all as well as 200 Tate expansion staybolts on the entire roof of the combustion chamber.)
The N-1s were simpled in the 1920s, becoming N-2s and later N-3s in the process (Locobases 2802 and 6445, respectively).
These were the tallest locomotives on the Great Northern because the designers had to get the large firebox above the rearmost driving axle. Delivered as N-1 compounds by Baldwin in 1912 (Locobase 307), these engines were simpled in the mid-1920s, using Worthington feedwater heaters and generating 100,200 lb of tractive effort. The Belpaire firebox with its 81 sq ft (7.53 sq m) in the combustion chamber and 36 sq ft (3.34 sq m) arch remained unchanged. They did get 13" (330 mm) piston valves on all four cylinders. Moreover, the boiler sacrificed 64 small tubes for 18 more flues to accommodate a considerable increase in superheater area.
Some were converted to oil burning and trailed tenders carrying 17,000 US gallons (64,345 litres) of water and 4,600 gallons (17,411 litres) of fuel oil.
In the early 1940s they got new frames and roller bearings as well as a larger grate; at that point they became N-3s; see Locobase 6445
Delivered as N-1 compounds by Baldwin in 1912 (Locobase 307), these engines were simpled in the mid-1920s (N-2; Locobase 2802). S Kip Farrington, Jr, Railroading Coast to Coast (New York: Bonanza Books, 1976), p. 156. Note that they still had the characteristic Belpaire firebox.
In the early 1940s, the N-2 class (Locobase 2802) got new General Steel Casting Co cast-steel beds, new Baldwin-built nickel-steel boilers, and Timken roller bearings as well as a larger grate; at that point they became N-3s. The firebox was reworked and had a larger combustion chamber contributing 144 sq ft (13.38 sq m) to firebox heating surface area. An additional 33 sq ft (3.07 sq m) came from arch tubes. A comparison with the 1912 compound N-1's factors (Locobase 307) shows what a huge increase in power these rebuilds represented.
The railway substituted exhaust steam injectors for the Worthington feed water heaters installed in the 1920s. Elesco supplied the injectors for 2000, 2003-2009, 2016, and 2022. 2012 had one Elesco and one Sellers injector. The other 14 had Sellers injectors. Below the boiler, the railroad installed Timken roller bearings on all driving axles.
The timing couldn't have been better, either. The first of the rebuilds (2024) was completed on 10 February 1940, the last (2009) wrapping up almost exactly two years later on 12 February 1942. Thus the greater horsepower was available in time for the Great Northern's World War II traffic spike.
And did the N-3s ever deliver, according to Charles R. Wood, in Lines West (New York: Bonanza Books, 1967), p 109, describes them as: "Amazing engines, they hauled ore on the iron range, hustled time freights on the Kalispell Division and served in heavy duty passenger service on troop trains." On the latter service, Wood quotes Mr. J S Miller, Assistant to the Superintendent of Motive Power in 1945/46 as saying that N-3s could "...run like a deer" and hit speeds of 50-60 mph.
S Kip Farrington recorded a 17 November 1943 cab ride on Extra 2014 East as it pulled 180 cars weighing a total of 16,740 tons (15,218 tonnes).
Virtually all of the class was retired in 1955.
|Specifications by Steve Llanso of Sweat House Media|
|Railroad||Great Northern (GN)||Great Northern (GN)||Great Northern (GN)|
|Number in Class||25||25||25|
|Locomotive Length and Weight|
|Ratio of driving wheelbase to overall engine wheebase||0.36||0.38||0.38|
|Overall Wheelbase (engine & tender)||52.50'||98'||99.67'|
|Axle Loading (Maximum Weight per Axle)||52500 lbs||52500 lbs||57400 lbs|
|Weight on Drivers||420000 lbs||420000 lbs||459200 lbs|
|Engine Weight||450000 lbs||450000 lbs||489200 lbs|
|Tender Light Weight||154000 lbs||365400 lbs||365400 lbs|
|Total Engine and Tender Weight||604000 lbs||815400 lbs||854600 lbs|
|Tender Water Capacity||8000 gals||21500 gals||21500 gals|
|Tender Fuel Capacity (oil/coal)||13 tons||24 tons||24 tons|
|Minimum weight of rail (calculated)||88 lb/yard||88 lb/yard||96 lb/yard|
|Geometry Relating to Tractive Effort|
|Boiler Pressure||210 psi||210 psi||265 psi|
|High Pressure Cylinders (dia x stroke)||28" x 32"||25" x 32"||22" x 32"|
|Low Pressure Cylinders (dia x stroke)||42" x 32" (2)|
|Tractive Effort||98422 lbs||113333 lbs||110751 lbs|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||4.27||3.71||4.15|
|Firebox Area||326 sq. ft||359 sq. ft||436 sq. ft|
|Grate Area||78.40 sq. ft||78.40 sq. ft||95 sq. ft|
|Evaporative Heating Surface||6446 sq. ft||5837 sq. ft||5782 sq. ft|
|Superheating Surface||1368 sq. ft||1868 sq. ft||2188 sq. ft|
|Combined Heating Surface||7814 sq. ft||7705 sq. ft||7970 sq. ft|
|Evaporative Heating Surface/Cylinder Volume||282.65||160.53||205.34|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||16464||16464||25175|
|Same as above plus superheater percentage||19428||20415||31972|
|Same as above but substitute firebox area for grate area||80783||93484||146736|