Great Northern 4-8-4 "Northern" Locomotives

The Great Northern Railway obtained its first "Northerns" in 1929, when six Class S-1s were delivered from the Baldwin Locomotive Works. These 4-8-4s were given road numbers 2550 through 2555 and had 73" drivers, 28 x 30 cylinders, a boiler pressure of 250 psi, a weight of 472,120 lbs and a tractive effort of 68,466 pounds.

In 1930, 14 Class S-2s (road numbers 2575 through 2588) came from Baldwin with 80" drivers. With 73" drivers, the S-1s were better suited for dual service, but the S-2s were truly passenger locomotives. The Class S-2s had 29 x 29 cylinders, a 225 psi boiler pressure, a weight of 420,900 lbs and a tractive effort of 58,300 pounds.

There is only one surviving GN "Northern", number 2584 at a depot in Havre, MT.

Roster by Richard Duley

Class Road Numbers Year Built Builder
S-1 2550-2555 1929 Baldwin
S-2 2575-2588 1930 Baldwin

Class Details by Steve Llanso of Sweat House Media

Class S-1 (Locobase 261)

Data from 1930 Locomotive Cyclopedia; see also DeGolyer, Vol 81 pp. 503+ . Works numbers were 60781-60782 in April 1929, 60807-60810 in May.

Heavy dual-service oil-burning engines. GN's signature improved Belpaire firebox was joined to a combustion chamber that contributed 108 sq ft (10.03 sq m) to the firebox heating surface. Unlike many other large superpower engines of the time, this design had no arch tubes or syphons. And the Elesco exhaust steam injector was less common than feed water heaters. It was rated at 10,000 US gallon capacity. Steam admission came through 14" (356 mm) piston valves.

Only six built before design changed to lighter engine with high drivers (Locobase 262). They were nonetheless highly serviceable locomotives that remained in service until 1956 (2553), 1957, and 1958.


Class S-2 (Locobase 262)

Data taken from DeGolyer, Vol 82, pp. 283+ and Great Northern locomotive diagram reproduced on Ben Ringnalda's http://www.greatnorthernempire.net/index2.htm?GNEGN_S2_Class.htm website, last accessed 16 February 2007. See also Charles R Wood, Lines West (New York: Bonanza Books, 1967), pp. 88 inter alia; and The Great Northern Empire Then and Now website at http://www.greatnorthernempire.net/index2.htm?GNEGN_S2_Class.htm, last accessed 3 July 2015.(Thanks to Chris Hohl for his 24 April 2015 email noting the use of coal in some GN S-2s and for callling attention to the high weights shown in the specs.) Data differs slightly from the 1930 Locomotive Cyclopedia specs. Works numbers were 61211-61216, 61224-61225, 61237-61242 in February and March 1930.

The S-2 had high drivers and smaller boilers than the earlier S-1 (Locobase 261) and was more completely dedicated to express passenger service. In fact, Charles Wood noted, these were the first 4-8-4s to have 80" drivers and would be the only such engines until 1937. Turning on friction bearings when delivered, the S-2s would get Timken roller bearings in 1945.

Another change was the squaring of the cylinder dimensions so that diameter equalled stroke. This resulted in slightly more cylinder volume. The boiler was fitted with a Sellers exhaust steam injector that could process 4,500 to 7,350 US gallons (17,033 to 27,820 litres) per hour. Even in mid 1940s, the S-2's adhesion and engine weights were only slightly higher than the specified weight limits in the original order.

To save weight, the GN eschewed their by-then standard Belpaire firebox in favor of a radial-stayed firebox. This large cavity had a combustion chamber (111 sq ft/10.3 sq m) as delivered; 22 sq ft (2.05 sq m) of arch tubes were installed later.

Like their predecessors, the S-2s were oil-fired, but the specs required that the frames were "to be arranged on frame with flat surface for future application of stokers." The class burned oil for most of their 25+-year careers and had the only all-welded tenders on the GN. Some S-2s were converted temporarily in the late 1930s to burn coal and trailed tenders carrying 17,000 US gallons of water and 24 tons of coal.

Wood's assessment of the class was mostly laudatory: "Long winded engines, fast and durable, their only fault was a tendency to be very slippery when starting a heavy train." (p. 96). Engineers developed a starting technique when the S-2 was hitched to a freight train that Wood said "[M]uch to the consternation of the Master mechanic" would set the engine's air, pull the engine's throttle, and release the air. "Th added kick would urge tonnage into motion without wild slipping." There was a big risk, however, in the engine "slipping a driver tire and taking the locomotive out of service." (p. 99).

By 1949 the S-2s had been supplanted in Empire Builder service and relegated to secondary duties.

Specifications by Steve Llanso of Sweat House Media
Class S-1 S-2
Locobase ID 261 262
Railroad Great Northern (GN) Great Northern (GN)
Country USA USA
Whyte 4-8-4 4-8-4
Road Numbers 2550-2555 2575-2588
Gauge Std Std
Builder Baldwin Baldwin
Year 1929 1930
Valve Gear Walschaert Walschaert
Locomotive Length and Weight
Driver Wheelbase 19' 20.75'
Engine Wheelbase 45.50' 47.75'
Ratio of driving wheelbase to overall engine wheebase 0.42 0.43
Overall Wheelbase (engine & tender) 94.90' 91.17'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers 273700 lbs 247300 lbs
Engine Weight 472120 lbs 420900 lbs
Tender Light Weight 375780 lbs 326560 lbs
Total Engine and Tender Weight 847900 lbs 747460 lbs
Tender Water Capacity 22000 gals 17250 gals
Tender Fuel Capacity (oil/coal) 5800 gals 5800 gals
Minimum weight of rail (calculated) 114 lb/yard 103 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter 73" 80"
Boiler Pressure 250 psi 225 psi
Cylinders (dia x stroke) 28" x 30" 29" x 29"
Tractive Effort 68466 lbs 58305 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.00 4.24
Heating Ability
Firebox Area 401 sq. ft 401 sq. ft
Grate Area 102 sq. ft 97.75 sq. ft
Evaporative Heating Surface 5405 sq. ft 4781 sq. ft
Superheating Surface 2444 sq. ft 2265 sq. ft
Combined Heating Surface 7849 sq. ft 7046 sq. ft
Evaporative Heating Surface/Cylinder Volume 252.80 215.65
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation 25500 21994
Same as above plus superheater percentage 33405 29032
Same as above but substitute firebox area for grate area 131328 119097
Power L1 41834 36767
Power MT 1347.87 1311.08

Photos

Reference


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