Great Northern Other Articulated Locomotives in the USA

Class L-3/M-1 - 1st batch (Locobase 352)

Data from GN 1916 Locomotive Diagram supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also DeGolyer, Volume 34, pp. 45+ and "Mallet Articulated Locomotives, 2-6-8-0", American Engineer and Railroad Journal, Volume 84

No. 10 (October 1910), pp. 108-109. (Thanks to Torsten Sohns for his 7 February 2021 email noting a mismatch in class count.) Works numbers were 34024-34028, 34074-34076 in November 1909; 34104-34105 in December.

Similar to Southern Ls engines (Locobase 293), these M-2s were heavier, and had slightly smaller drivers, smaller "separable" boilers with GN's trademark Belpaire fireboxes, lower superheat ratio, and a different assortment of tubes. Fitted with Emerson feed water heater of 1,777 sq ft (165.09 sq m) in the tubes, which was soon removed. and a. This vessel contained 582 tubes, each measuring 5 ft (1,524 mm) long and 2 1/4" (57 mm) diameter. All of the feed water heater's cross section contained these small tubes except for the center core that contained a 11" (279 mm) flue.

Locobase's specifications show the locomotives after the Emerson superheater was removed.

Another oddity was the use of two different diameters of piston valves. The HP cylinders were supplied by 13" (331 mm) piston valves while 15" (381 mm) piston valve fed the LP cylinders.

They were soon joined by bigger versions of the same design; see Locobase 13537.

Some were simpled; see the M-2 simple entry (Locobase 2800). 22 were converted in 1929-1931 to 69"-drivered 2-8-2s and designated O-7s.

Class L-3/M-1 - 2nd batch (Locobase 13536)

Data from GN 1916 Locomotive Diagram supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange and Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University, Volume 34, pp. 50+. Works numbers were 34824-34833 in June 1910. See also "The Mallet Compound", Railroad & Locomotive Engineering, Volume XXIV [24], No 11 (November 1911). p. 8.

Like the first batch described in Locobase 352, this set of GN articulateds were delivered with the trademark Belpaire fireboxes, low superheat ratio, Emerson feed water heater of 1,777 sq ft (165.09 sq m) in the tubes, which was soon removed, and a feedwater heater.

One big difference was the addition of more than 100 tubes to the boiler. Loaded weight on the front three axles came t 164,000 lb (74,389 kg) and on the rear four axles, it was 185,000 lb (83,915 kg).

In November 1911, the R&LE took up the question of the Mallet compound as addressed in a report to the Traveling Engineers' Association. Interviews with the mechanical staff of three railroads including the GN. Noting that such engines were "by no means a favorite type of power with trainmen", it added "but it is forcing its way into favor for the reason that it does the work of train hauling at less expense than any other type of locomotive." Perhaps unsurprisingly, the R&LE had heard "that engineers and firemen in certain quarters are scheming to make a combined effort to oppose the use of Mallet engines in road service."

Focusing on the GN, the report claimed that these Mallets performed road service that was "decidedly more economical than that of consolidations, although the Mallets have driving wheels only 55 ins diameter [sic]." Another advantage the GN cited "considerably less shock to the train than the consolidation in passing over grades." Their conclusion was "because both units of the Mallet never slip at the same time." Moreover, "the slack of the train does not up as in the case of a consolidation engine." ("A peculiarity that might be expected", added R&LE, was the consolidation engine's "faculty of running a train over a grade faster than the Mallet."

The specifications show the locomotives after the Emerson superheater was removed.

Some were simpled; see the M-2 simple entry (Locobase 2800). 22 were converted in 1929-1931 to 69"-drivered 2-8-2s and designated O-7s.

Class M (Locobase 16380)

Data from GN 1916 Locomotive Diagram supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also "The Converted Mallet Locomotive, Railroad Age Gazette, Volume XLVII [47], No 23 (3 December 1909) and "Converted Mallet Locomotive for the Great Northern", RAG, (17 December 1909), pp. 1185-1186; Model Railroad Hobbyist website's account of the "Great Northern Railway's odd-ball steam locomotive The M Class 2-6-8-0" , last accessed at [] on 4 December 2018. (Many thanks to Chris Hohl for his 17 November 2018 email and spreadsheet supplying the details of this one-of-a-kind variant of a very rare wheel arrangement.)

This was a an oddball Mallet to begin with. It was rebuilt from GN F-8 wide-firebox Consolidation #1254 (Locobase 13050), adding a Baldwin-built forward boiler section that included the six-coupled front, low-pressure engine. A Baldwin feed water heater was installed in that section. This component consisted of 345 two-inch (50.2 mm) tubes each 8 ft (2,438 mm) long and credited with 1,473 sq ft (136.85 sq m) in surface area. By 1916, the low-temperature heater had been removed.

The 2000 (later 1999) had smaller dimensions than other GN M-class engines (Locobases 352 and 13536) in every respect except for the driver diameter. In a strange inversion from the usual setup, the low-pressure cylinders driving the front engine in the M2 were supplied steam through piston valves while the HP cylinders were fed through traditional D-type slide valves. The GN planned to install an Emerson superheater in the original Consolidation boiler.

It's difficult to determine how successful this hybrid proved to be, but it was converted in 1926 to C-4 class 0-8-0 switcher #8701 (later renumbered 780 in 1929).

Class M-2 - simple (Locobase 2800)

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

One of the few classes of locomotives delivered with the odd 2-6-8-0 arrangement. Drury (1993) speculates that it was adopted as a way to get more adhesion. As delivered they were M-1 compound engines (see Locobases 352 and 13536) , but they were simpled in 1926-1928. In keeping with their unusual arrangement, the rebuild gave them front cylinders 22" in diameter, the rear ones 23 1/2", each of which took steam through 13"(330 mm) piston valves. GN calculated the class's tractive effort as 95,500 lb (43,318 kg) based on a 65% cutoff setting on the front set and 85% cutoff on the rear set.

Axle loading on each of the three front axles was 56,000 lb (25,401 kg), which combined for a loaded adhesion weight of 168,000 lb (76,204 kg). The four rear coupled axles each had a 54,000 lb (24,494 kg) axle loading and the set's loaded adhesion weight added up to 216,000 lb (97,976 kg).

See Larry Bohn photograph ([]) for an illustration of the rebuild.

Charles R. Wood, in Lines West (New York: Bonanza Books, 1967), commented about these engines (p 66): "Essentially, [they] were slow-speed locomotives and any attempt to push the speed was hard on the engine and track." Watching the side rods carve great swaths of space close to the ground led some enginemen to dub them "grass-cutters." Wood continues: "Rough -riding at any speed above 25 mph [40 kph], they vibrated with a fierce clatter of gangway plates and jingle of cab gauges. As one engineer put it, 'I couldn't even keep my shoelaces tied.'"

Under another photo of the M-2 on p 67, Wood attributes the roughness to large counterweights on the last set of drivers under the cab. And the lack of trailing truck meant that a backing M-2 "...met every rail joint and switch point head on, and changed the angle of direction with a very positive lurch." Yet, Wood concedes, these engines had their place in the GN's scheme of operations:

"[W]ith all their faults, they could move tonnage - not very fast to be sure - but between Butte and Great Falls they would come slogging up the grade under a vast canopy of smoke and cinders while the front bandstand articulated to the curves and the exhaust bounced off the hills and mountainsides."

Continuing the GN's policy of converting light articulated locomotives to 2-8-2, the railroad began converting M-2s to O-7 Mikados (Locobase 7448) within in a year after its last simple-expansion reconstruction.