The Great Northern Railway running from Saint Paul, Minnesota, to Seattle, Washington more than 1,700miles . It was the creation of the 19th century railroad tycoon James J. Hill and was developed from the St. Paul and Pacific Railroad. The Great Northern's route was the northernmost transcontinental railroad route in the United States and was north of the Northern Pacific Railway route. It was completed on January 6, 1893, at Scenic, Washington.

The Great Northern was the only privately funded, and successfully built, transcontinental railroad in United States history. No federal land grants were used during its construction, unlike every other transcontinental railroad built.

The Great Northern Railway received its first "Mikado" type locomotives in 1911. Built by the Baldwin Locomotive Works, these locomotives, designated as Class O-1, were assigned road numbers 3000 through 3019. Built with 180 psi boiler pressure (later raised to 210 psi), 63" diameter drivers, 28" x 32" cylinders, they exerted 60,928 pounds of tractive effort and each weighed 280,000 pounds. The firebox was 244 square feet, the evaporative heating surface was 4,745 square feet and with the superheater the combined heating surface was 5,646 square feet.

In 1913, Baldwin delivered fifty oil-fired "Mikados" which were also designated as O-1 with road numbers 3020 through 3069. These locomotives had 63" diameter drivers, 28" x 32" cylinders, they exerted 60,938 pounds of tractive effort and each weighed 315,360 pounds. The firebox was 284 square feet, the evaporative heating surface was 4,714 square feet and with the superheater the combined heating surface was 5,732 square feet.

From 1916 through 1918, another seventy-five Class O-1 locomotives were added to the roster and given road numbers 3070 through 3144. These locomotives had 63" diameter drivers, 28" x 32" cylinders, a 180 psi boiler pressure which was later raised to 210 psi, they exerted 60,938 pounds of tractive effort and each weighed 306,500 pounds. The firebox was 284 square feet, the evaporative heating surface was 4,693 square feet and with the superheater the combined heating surface was 5,611 square feet.

A single locomotive was acquired through a merger with the Watertown & Sioux Falls. This locomotive was designated as Class O-2 and it was assigned road number 3149. It was built by the American Locomotive Company in 1915 for the South Dakota Central. This locomotive had 52" diameter drivers, 20" x 28" cylinders, a 180 psi boiler pressure, it exerted 32,954 pounds of tractive effort and it weighed 178,000 pounds. The firebox was 148 square feet and the evaporative heating surface was 2,520 square feet.

Nine USRA allocated "Mikado-Heavy" locomotives, were added to the roster in 1919. These American Locomotive Company built locomotives were designated as Class O-3 and assigned road numbers 3200 through 3208. They had 63" diameter drivers 27" x 32" cylinders, a 190 psi boiler pressure and they exerted 59,801 pounds of tractive effort and each weighed 320,000 pounds. The firebox was 319 square feet, the evaporative heating surface was 4,293 square feet and with the superheater the combined heating surface was 5,286 square feet.

In 1920, the Baldwin Locomotive Works delivered thirty-five Heavy "Mikados" which were designated as Class O-4 and given road numbers 3210 through 3254. They had 63" drivers 28" x 32" cylinders, a 190 psi boiler pressure and they exerted 64,310 pounds of tractive effort and each weighed 319,700 pounds. The firebox was 283 square feet, the evaporative heating surface was 4,455 square feet and with the superheater the combined heating surface was 5,583 square feet.

By the 1920s the 2-6-6-2s the GN had purchased in 1906-1908 were being replaced by newer and more powerful articulated locomotives. The boilers in these locomotives were judged to be the right size for 2-8-2s and in 1922 the GN began a program to rebuild the 45 Class L-2s into "Mikado" type locomotives. This group was designated as Class O-5 and assigned road numbers 3300 through 3344. These new 2-8-2s had 63" drivers, 25" x 30" cylinders, a 200 psi boiler pressure, they exerted 50,595 pounds of tractive effort and each weighed 283,430 pounds. The firebox was 237 square feet, the evaporative heating surface was 3,071 square feet and with the superheater the combined heating surface was 3,876 square feet.

In 1925, the GN had completed the 45 Class O-5s and started rebuilding 22 more 2-6-6-2s. By 1926 the GN had rebuilt 22 of the Class L-1s into another class of 2-8-2s. This new group was completed in 1926 and was designated as Class O-6 and assigned road numbers 3350 through 3371. These locomotives had 56" drivers, 28" x 32" cylinders, a boiler pressure of 195 psi and they exerted 74,256 pound of tractive effort and each weighed 320,000 pounds. The firebox was 269 square feet, the evaporative heating surface was 4,516 square feet and with the superheater the combined heating surface was 5,644 square feet.

In 1909, the Great Northern bought 35 Class M-1, "Mallets" of an unusual wheel arrangement, 2-6-8-0. In 1924-1925, the railroad rebuilt these locomotives as simple engines and designated them as Class M-2. Not satisfied, the GN decided to rebuild 22 of the M-2a as a new and very large 2-8-2, which it designated as class O-7. This rebuilding program began in 1929 and was completed in 1932. The locomotives were assigned road numbers 3375 through 3396 and took the GN into the field of truly giant 2-8-2s. They had 69" drivers, 31" x 32" cylinders, a 210 psi boiler pressure, exerted 79,554 pounds of tractive effort and each weighed 348,000 pounds. The firebox was 258 square feet, the evaporative heating surface was 5,240 square feet and with the superheater the combined heating surface was 6,730 square feet.

In 1932, the GN built three "Mikados" in its own shops. They were designated as Class O-8 and were given road numbers 3397 through 3399. These locomotives had 71" drivers, 28.5" x 32" cylinders, a 250 psi boiler pressure, they exerted 77,793 pounds of tractive effort and each weighed 376,000 pounds. The firebox was 445 square feet, the evaporative heating surface was 4,781 square feet and with the superheater the combined heating surface was 6,891 square feet. The GN Class O-8 "Mikados" were the only locomotives constructed in the U.S. that year for domestic service.

Seemingly, the GN was not satisfied with the O-7s, so new boilers were ordered from Baldwin and ALCO, and the twenty-two O-7's were rebuilt during 1944, 1945 and 1945. They were classified as Class O-8s and joined the three that were built in 1932. These new Class O-8s had 71" drivers, 28.5" x 32" cylinders, a 250 psi boiler pressure, they exerted 77,793 pounds of tractive effort and each weighed 425,540 pounds. The firebox was 506 pounds, the evaporative heating surface was 4,726 square feet and with the superheater the combined heating surface was 6,836 square feet. In 1946, the three locomotives built in 1932 were rebuilt to conform to the "new" O-8s specifications, thus making a class of twenty-five. Also, over time, some, if not all, of the class were converted to oil burners. They were not only the heaviest "Mikado" type ever built, but had a higher axle loading (81,000 lb) than most steam locomotives.

There is one surviving Great Northern 2-8-2 "Mikado" type locomotives. It is a Class O-1, number 3059, which is on display at a city park in Williston, ND.

Class O-1 - 1st batch (Locobase 8856)

Data from GN 1916 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection. See also "Superheater Locomotives 2-8-2 Type", American Engineer and Railroad Journal, Vol 85, No 11 (November 1911), pp. 424-427. Works numbers were 36832-36833 in August 1911; 36910-36917, 36937-36942, 36969-36972 in November.

First of a long run of Mikados for the Great Northern, all of which were built to the same basic set of specs. Like so many GN engines, these had Belpaire fireboxes.

The AERJ article contains an assertion about the popularity of the Mikado arrangement that confounds the reader in view of the design's later widespread use. At the time of writing in late 1911, the recent revival in the procurement of the 2-8-2 surprised many who had written the arrangement off 4 or 5 years before in favor of articulated Mallet compounds.

And the writer tells us why this has happened:

"The reason for this renewed lease of life will be found principally in the success of the high degree superheater which has so greatly increased boiler capacity as to permit a boiler of sufficient capacity per unit of weight to be mounted on four coupled drivers without exceeding a safe axle load, and enable the locomotive to deliver a very high ratio of its maximum tractive effort at moderately high speeds. In the September issue, on page 346 [i.e., the September 1911 issue of AERJ], will be found a discussion of the comparative merits of the consolidation and the Mikado type locomotive, wherein it is pointed out that while the maximum theoretical tractive effort of the Mikado could be attained by the consolidated type, it is the sustained high tractive effort at high speed, which means boiler capacity, that is assured by the former."

And on the Great Northern, as on most other railroads that tried them, the Mike firmly established itself as a puissant freight hauler. Most O-1s were scrapped more than 40 years later in the mid-to-late 1950s.

Class O-1 - 2nd batch (Locobase 1350)

Data from GN 1916 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection. See also DeGolyer, Vol 43, pp. 26+. Works numbers were 39089-39104, 39150-39158, 39163-39172 in January 1913; 39205-39212 , 39296-39302 in February.

After the first 20 O-1s were delivered, the design was reconfigured to give up some tubes for flues and increase the superheater surface area. Like so many GN engines, these had Belpaire fireboxes. Piston valves measured 13" (330 mm). The first two were delivered with an Emerson superheater.

Most were scrapped in the mid-to-late 1950s.

Class O-1 - 3rd batch (Locobase 8857)

Data from GN 1916 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection. See also DeGolyer, Vol 55, pp. 320-343.

After the first 20 O-1s were delivered, the design was reconfigured to give up some tubes for flues and increase the superheater surface area. Like so many GN engines, these had Belpaire fireboxes. The GN diagrams shows 32 more sq ft (3 sq m) of firebox heating surface than does the Baldwin spec, reflecting the almost immediate addition of arch tubes.

Details on the last two batches:

Engine numbers 3070-3094

Baldwin works numbers

1916

August 43989-43993; September 44095-44099, 44144-44146; October 44197-44204, 44253-44254; November 44438-44439

3095-3144

1917

August 46066-46068, 46110, 46163, 46213; September 46277; November 46891

1918

March 48150; April 48257-48260, 48468; May 48524, 48573, 48675-48676, 48732-48733, 48775; June 48893, 48943, 48995, 49079-49080; July 49158, 49226, 49299-49300, 49356-49357, 49408; August 49481-49482, 49639, 49659-49661; September 49731, 50051; October 50359-50360; December 51011

1919

January 51035, 51083, 51156; February 51234-51236.

Note the broken series and the year-and-a-half duration of the construction of this last batch. This period encompassed the moments of greatest strain on the private management of the US railroad system, the establishment of the USRA, the design and construction of USRA-standard locomotives. A comparison shows that this design was quite a bit bigger than even the USRA heavy locomotive.

Most were scrapped in the mid-to-late 1950s.

Class O-2 (Locobase 8858)

Data from GN 1916 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection. See Locobase 7460 for a short history of the SF & N.

A small Mikado originally delivered to this northeast Washington railway.

Class O-2 (Locobase 9470)

Data from GN 1 - 1929 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

The Great Northern diagrams do not supply a superheater surface area; the figure shown in the specs is an estimate based on similar installations in other locomotives. Steam admission came through 11" piston valves.

This was a single Mikado supplied to the SDC in 1915 (works #55444), a railroad with a sketchy financial base that had a 100-mile mainline between Watertown and Sioux Falls. A tragic accident in 1916 led a court to direct its sale to the W & SF, a railway created by the Great Northern in 1916. The Great Northern didn't own the SDC's trackage outright until 1930, but by 1921, it given this little Mike its own class ID and renumbered it. As such, it carried on unaltered until it was retired in April 1947 and scrapped in March 1949.

Class O-3 (Locobase 6446)

Four of these USRA Heavy Mikados went straight to the Great Northern as class O-3 (works # 61038-61041); that railroad diagrammed them as shown on http://www.greatnorthernempire.net/index2.htm?GNEGNPrototypeDrawingsSteam.htm (visited 7 Jan 2005). Five that were intended for the El Paso & Southwestern as their 390-394 were produced in November 1918 (Alco works #60400-404), but were operating on the GN by the end of 1920.

Class O-4 (Locobase 7451)

Data from GN 1 -1929 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection. Works numbers were 53597

53598 in August 1920; 53622-53623, 53649-53650, 53681-53683, 53707, 53747-53750 in September; 53792-53794, 53834-53835, 53836-53838, 53866, 53911-53912 in October; 53940-53942, 53985-53986, 54027-54035, 54091-54092, 54102, 54123-54124 in November

Similar to the prewar O-1s, whose basic power dimensions this new class repeated, these Belpaire-boilered Baldwins were bigger and heavier, but they extended the line. They had 35 sq ft of arch tubes as part of the firebox heating surface and 14" piston valves.

Withdrawal came in two big waves. The mid-50s saw the outright scrapping of over half the class in 1955 and 1956 (a few had preceded the big clump and were scrapped singly in 1950-1953). 19 were retired in the late 1950s, but held in reserve for a few years, then scrapped in 1962.

Class O-5 (Locobase 7450)

Data from GN 1 -1929 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

As noted in Locobase 7449, the Great Northern recycled much of its early articulated power into 2-8-2s. This batch was the first to be made over and its source material was the L-2 class of 2-6-6-2s that had come on the railway about 15 years before. In addition to making room for a modest number of flues and superheater elements, the shops also added 31 sq ft of arch tubes to the firebox. Simpling the locomotive meant installing 12" piston valves for the two remaining HP cylinders, which were not especially large for the time.

By the time of their retirements in the late 1940s, the O-5s had seen very few significant changes.

Class O-6 (Locobase 7449)

Data from GN 1 -1929 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

The Great Northern conserved as much of its motive power as it could. When a design's original purpose and arrangement didn't serve later purposes, the railway pulled the locomotive into the shop and soon rolled out a new, fresh engine for the task. In the case of the L-1 2-6-6-2s (Locobase 5354 & 819) , their role had been taken over by the 2-8-8-2s and the GN cut and chopped and whittled the articulated design into a reasonably powerful, low-drivered, and superheated Mikado modeled after the O-4 class of 1920 (Locobase 7451). It retained the Belpaire firebox of the articulated and used 14" piston valves to feed the two large cylinders. Firebox heating surface area included 39 sq ft of arch tubes.

Class O-7 (Locobase 7448)

Data from GN 1 -1929 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

Locobase 2800 describes the simpled variant of the M-2 2-6-8-0s created by the railway in the mid-teens. In the late 1920s, the GN modified the basic frame again (but retained the Belpaire firebox) and created these outsized Mikados with unusually tall drivers. They were big and had 15" diameter piston valves supplying very large cylinders. Locobase is surprised at the relatively puny firebox heating surface, which was deprived of the benefits of a combustion chamber until the shops later cut 5 feet off the tubes and flues. At that point, they were redesignated O-8; see Locobase 16 for the result

Class O-8 (Locobase 16)

Data from GN 4 -1946 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

Drury (1993) confirms an impression elicited by the data: "The O-8s generally take honors for North America's heaviest, fastest, and most powerful Mikados." Even as delivered, the firebox supplied a hefty amount of heating surface area, which included 90 sq ft in the combustion chamber and 39 sq ft of arch tubes. Adding the combustion chamber helped smooth the lines of the Belpaire firebox, but it added a kink in the upper profile. Piston valves measured 14" in diameter.

Three of the engines were delivered from the shops in 1932. GN's shops added twelve more in 1944 by rebuilding O-7s, which had themselves been rebuilt from 2-6-8-0s. Most were later reconfigured with more direct heating surface and 25 tons more adhesive weight; see Locobase 7447.

Class O-8 - modified (Locobase 7447)

Data from GN 3 -1952 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

Locobase 16 notes Drury (1993) as describing this class as the biggest and most powerful class of Mikados. How much more so when the firebox heating surface is further augmented in the GN's shops by removing the arch tubes and installing 100 sq ft (9.3 sq m) of circulators in the Belpaire firebox. For some reason, weight soared to an axle loading nearing 41 tons, although most of the axles now had Timken roller bearings.