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
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.