Great Northern 4-4-2 "Atlantic" Locomotives in the USA

Class K-1 (Locobase 6945)

Data from GN 1916 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also DeGolyer, Volume 29, pp. 12+ and "New Locomotives for the Great Northern," Railroad Gazette, Volume XLI [41], No 17 (26 October 1906), p. 371. (Thanks to Chris Hohl for his comments on this class's tender capacity in his 18 February 2015 email.) Works numbers were 28037-28038 in April 1906; 28078, 28092, 28107-28108, 28148, 28162, 28198, 28270 in May.

Drury (1993) notes that these were delivered in 1906 as Vauclain balanced compound engines. Although Baldwin's balanced compounds were laid out with the four cylinders in line abreast under the smokebox, they didn't always drive the same axle. In the case of this Atlantic decade, the 15" HP cylinders sat inside the frame and drove the first coupled ax

le; the 25" LP cylinders sat outside and drove the second. Each side's HP and LP cylinders were supplied through a single 15" (381 mm) piston valve.

Baldwin's specs estimated adhesion weight at 105,000 lb (47,672 kg) and RG offered 112,000 lb (50,802 kg); Locobase uses GN 1916 figure, which splits the difference. Their boilers displayed the GN's preference for square-shouldered Belpaire fireboxes and their heating surface areas were identical to those of the freight Prairies bought in the same year (Locobase 5388).

Drury's observation about their 73" drivers suggesting no great turn of speed bears remembering when the basic idea of the 4-4-2 arrangement was to provide more power to express passenger trains. But the RG report said that the engines had been put to work on the "Oriental Limited service between the MIssissippi River to the coast."

GN superheated these engines before 1916 beginning with 1706-1707. They were later simpled beginning in 1924; see Locobase 6944.

Class K-1-S (Locobase 6944)

Data from GN 1 -1929 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also Charles R. Wood, Lines West (New York: Bonanza Books, 1967), p. 60.

When the GN superheated their only Atlantics--Vauclain balanced compounds (Locobase 6945)--i the mid-teens, at least two of the engines (1706-1707) retained the four-cylinder layout. This entry describes the superheated update once it included simple expansion. The heating surface areas in the modified 4-4-2 were identical those in the J-1S. J-2-S freight prairies shown in Locobase 8853. They were big-boilered engines that got their steam through rather sizable 15" (381 mm) piston valves.

(17001, 1708-1709 were shown in later diagrams book to have 10"/254 mm piston valves; this seems a more likely value.) The class retained its Belpaire fireboxes whose heating surface areas now included 31 sq ft (2.88 sq m) of arch tubes.

In the process, the road gained a set of useful, mid-sized passenger engines, albeit ones with pretty high axle loadings.Moreover, according to Charles Wood, "Balancing of the running gear was always troublesome and many unusual combinations of counterweights were applied."

They were fitted with Delta trailing trucks holding booster engines that raised starting tractive effort to 36,800 lb (16,692 kg or 163.69 kN).

At least one remained in service through World War II. The GN also rebuilt the Spokane, Portland & Seattle's ten compounds; see Locobase 16531.