Great Northern / South Dakota Central 2-8-2 "Mikado" Locomotives in the USA

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

Data from DeGolyer, Volume 42, pp. 276+. See also GN 1916 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange; and"Superheater Locomotives 2-8-2 Type", American Engineer and Railroad Journal, Volume 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. Superheated steam entered the cylinders through 13" (330 mm) piston valves. Although delivered with boilers set to 170 psi, the O-1s later ran with pressures set at 210 psi (14.48 bar). Concerns over the transverse equalizing beams led to a "Hereafter" note stating that the beams were to be strengthened "by filling in the channel and making a rectangular section between the frames."

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 four or five 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 Rail Data Exchange. 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 Rail Data Exchange. 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 (Locobase 41).

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 Rail Data Exchange. Works number 55444 in October 1915

This small Mikado was originally delivered to this Upper Plains railroad, chartered in 1902. was very soon transformed as the Watertown & Sioux Falls in 1916.This was a single Mikado supplied to the South Dakota Central 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 W&SF's trackage outright until 1930, but by 1921, it given this little Mike its own class ID and renumbered it 3149. GN also installed a modest superheater (Locobase 9470. Of all the GN Mikes built as such, this engine had by far the smallest drivers (the next taller diameter was 63")

Although a nonpareil in the GN's 2-8-2 numbers, the 3149 remained in service throughout World War II. The GN retired it in April 1947 and scrapped it in Minneapolis in March 1949.

Class O-2 (Locobase 9470)

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

At some point after its 1916 adoption by the GN's newly acquired Watertown & Sioux Falls, this little Mikado (Locobase 8858) received the superheater installation of modest proportions. Steam admission came through 11" (279 mm) piston valves.

As such, it carried on unaltered until it was retired in April 1947 and scrapped in March 1949

Class O-3 (USRA) (Locobase 6446)

Data from [] (visited 7 January 2005). (Thanks to Chris Rasmussen for his 27 February 2016 email pointing out the coal-to-oil burning conversion for this class.)

Four of these USRA Heavy Mikados went straight to the Great Northern as class O-3 (works # 61038-61041). Five more were intended for the El Paso & Southwestern as their 390-394 when they were produced in November 1918 (Alco works numbers 60400-60404 in November 1918). But the EP&SW found their coal facilities weren't suitable for serving this class, they were redirected to the GN in April 1919. The other four had works numbers 61038-61041 in March 1919. They were originally numbered 3145-3148, but took 3200-3203 upon delivery in April 1919.

Firebox heating surface area included 28.4 sq ft (2.64 sq m) of arch tubes and 45.1 sq ft (4.19 sq m) in the combustion chamber. Their cylinders were served by 14" (356 mm) piston valves. Delivered as coal-burners and trailing tenders carrying 16 tons of coal, this class was later converted to oil-burning, which entailed modifying the firebox and the tender.

3206 was scrapped in May 1948, fllowed by 3205 in December 1949, 3202 in October 1951, and 3207 in May 1953. The others all went in 1955 when dieselization was complete. 3201, 3204, and 3208 all went to the ferro-knacker in April and 3200 and 3203 finished the class in August.

Class O-4 (Locobase 7451)

Data from GN 1 -1929 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also DeGolyer Library, Vol 67, pp. 282+. (Thanks to Max Magliaro for his January 2015 email pointing out that both SP&S O-4s were oil-fired, which prompted the additional information shown below.) 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 (3.25 sq m) of arch tubes as part of the firebox heating surface and 14" (356 mm) piston valves. Delivered with boilers pressed to 180 psi (12.4 bar), the class soon had the pressure setting raised as shown in the specs.

By 1953, 37 O-4s had been converted to oil burning and trailed tenders holding 10,000 US gallons (37,850 litres) of water and 5,200 gallons of oil. Oil-burning road numbers were 3210-3219, 3221-3222,3225, 3227-3228, 3230,3232-3246, 3248-3249, 3251, and 3253. The other six still burned coal; 3229 and 3247 used even bigger tenders that held 15,000 gallons (56,775 litres) of water and 25 tons (22.7 metric tons) of coal.

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.

3211 and 3214 were sold to the SP&S in April 1950 and took road numbers 550-551; as shown in the table above, these were both oil-burners.

Class O-5 (Locobase 7450)

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

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 (Locobase 3554) that had come on the railway about fifteen years before. In addition to making room for a modest number of flues and superheater elements, the shops also added 31 sq ft (2.9 m) of arch tubes to the firebox. Simpling the locomotive meant installing 12" (305 mm) 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 Rail Data Exchange.

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).

The new Mikados retained the Belpaire firebox of the articulated and used 14" (356 mm) piston valves to feed the two large cylinders. Firebox heating surface area included 39 sq ft (3.6 m) of arch tubes.

Following their conversion, the class operated on the GN for decades. Except for 3365 (ex-1917), which suffered a boiler explosion in 1947, the class remained in service until the mid-1950s.

Class O-7 (Locobase 7448)

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

Locobase 2800 describes the 1926-1928 conversion of the M-class 2-6-8-0s (Locobase 13680). But the railway quickly took the step within a year of the last conversion. Superior Shops modified the basic frame again (but retained the Belpaire firebox and Duplex stoker) and created these outsized Mikados with unusually tall drivers. They were big and had 15" (381 mm) diameter piston valves supplying very large cylinders.

Locobase is surprised at the relatively puny firebox heating surface (even with arch tubes), which was deprived of the benefits of a combustion chamber until the shops cut five feet off the tubes and flues in another rebuild beginning in 1944. 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 Rail Data Exchange. See also Roy V Wright, 1947 Locomotive Cyclopedia of American Practice--13th edition (New York: Simmons-Boardman Publishing Corporation, 1947), p. 123; George H Drury, Guide to North American Steam Locomotives, Revised Edition (Waukesha, WI: Kalmbach Books, 2015), p. 181; and Kenneth R Middleton and Norman C Keyes, Jr, "Great Northern Railway Company: Predecessors and Controlled Subsidiaries", Railway and Locomotive Historical Bulletin 143 (Autumn 1980) , p. 102. (Many thanks to Chris Hohl for his 22 September 2017 email reporting unlikely boiler pressure values for 177 entries. A Locobase macro caused the error. Hohl's 30 December 2020 email raised questions about the stated driver and cylinder diameters, the response to which appears below. )

Although the O-7 (Locobase 7448) had the largest cylinder volume of any 2-8-2, its power was constrained by several inheritances from the M-2s like the small firebox and relatively low boiler pressure setting. Hillyard Shops drew up a clean sheet and designed and built this trio. New boilers from Baldwin (Order 5890) increased pressure by 40 PSI ( 2.76 bar), used a Type E superheater that increased superheating area by almost 50%.

Even as delivered, the firebox supplied a hefty amount of heating surface area, which included 90 sq ft (8.35 m) in a combustion chamber and 39 sq ft (3.6 m) of arch tubes. Adding the combustion chamber helped smooth the lines of the Belpaire firebox, but it added a kink in the upper profile. Its presence permitted a reduction in tube length, nearly achieving the often-sought ideal of a 100:1 length:diameter ratio. Piston valves measured 14" (356 mm) in diameter.

Most sources use the 28" cylinder diameter and 69" wheel diameter reported by Chris Hohl. He based his information on the figures given in the Great Northern's 1946 and 1952 diagram books. Locobase wondered about the this entry's use of 28 1/2" and 71", respectively. Reviewing his sources, Locobase found that the 1947 Locomotive Cyclopedia used that data. Yet even there, the given cylinder diameter disagrees with at least two sources (including the Railroad & Locomotive Historical Society), which give the 29" diameter now entered.

It was clear that as of 1946, all 25 O-8s had been converted to the same dimensions shown in Locobase 7447. Locobase supposes that the 1947 Cyclopedia's data referred only to the 1932 trio described here and has kept the differences

Drury confirms an impression elicited by the data: "The O-8s generally take honors for North America's heaviest, fastest, and most powerful Mikados."

For years, this trio remained unduplicated. GN's shops added twelve more in 1944 by rebuilding O-7s (Locobase 7448), 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 Rail Data Exchange collection. See also George H Drury, Guide to North American Steam Locomotives, Revised Edition (Waukesha, WI: Kalmbach Books, 2015), p. 181; and Kenneth R Middleton and Norman C Keyes, Jr, "Great Northern Railway Company: Predecessors and Controlled Subsidiaries", Railway and Locomotive Historical Bulletin 143 (Autumn 1980) , p. 102. . (Thanks to Chris Hohl for his 30 December 2020 email correcting the driver and cylinder diameters, differences in engine and tender wheelbases, and tender capacities.)

Locobase 16 notes Drury's description of the first three O-8 engines as the biggest and most powerful class of Mikados ever built. They were homebuilt at the GN's Superior Shops in 1932.

Beginning in 1944 and ending in late 1946, 22 O-7s (Locobase 7448) underwent their third reconstruction (from M to M-2 to O-7 to O-8) when they repeated much of the 1932 design and added a bit more. New boilers permitted a pressure increase of 40 psi (2.76 bar). Baldwin produced twelve of the vessels under order 305741 and Alco manufactured another ten in order 46650. A Type E superheater increased superheating area by almost 50%.

GN's shops addressed the O-7s' previously undersized firebox heating surface by removing the arch tubes, installing a combustion chamber that offered 90 sq ft (8.36 sq m), adding 100 sq ft (9.29 sq m) of security circulators.

Cylinder diameters were trimmed by 1" (50.8 mm) and served by piston valves reduced 1" to 14" (356 mm). The O-7s' 71" driver diameter dropped by 2" (50.8 mm) and all axles now turned in Timken roller bearings. The three 1932 O-8s, which had many of the upgrades already , received the remaining additions and deletions.

According to Hohl, "The total wheelbase slightly varied in the class depending on whether the locomotives had standard open cabs (83' 6 5/8"/25.47 m) or whether they retained their vestibule cabs (84' 3 5/8"/25.69 m) ."

Retirements came in a rush beginning with three in December 1957--3380, 3384, and 3388. All of the others were withdrawn in March and May 1958.