Class H (Locobase 9390)

Data from DeGolyer, Volume 26, p. 225 and Soo 9 - 1943 Steam Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. Works number was 23711 in February 1904)

The North Dakota railroad that bought this Baldwin served the capitol and surrounding communities. It began as the Bismarck, Washburn & Fort Buford in 1898, but soon extended its lines to the lignite mines of Wilton, which produced 1,000 tons of lignite per day (making it the largest lignite mine in the world) and boasted 400 miners in 1915 and were a significant source of revenue.

The Minneapolis, St Paul & Sault Ste Marie bought the railroad in 1904 and acquired this dainty Pacific (and a very similar 2-8-2 Vauclain Compound). It is one of the smallest standard-gauge 4-6-2s to have run in North America. The low axle loading suggests that the builder was supplying as many axles as he could to run on what must have been pretty light rail.

The later Soo diagram shows what was likely a new boiler which had 235 2" tubes instead of the original 2 1/4" tubes. Tube heating surface area dropped to 2,215 sq ft (205.78 sq m) with a commensurate evaporative heating surface area of 2,372 sq ft (220.45 sq m). Boiler pressure was reset to 180 psi (12.41 bar). Tender capacity later increased to 6,000 US gallons (22,710 litre ) and loaded weight to 124,400 lb (56,427 kg).

Class H-1 - superheated (Locobase 8743)

Data from Soo Miscellaneous Steam Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

Even after superheat was added to the original H-1 Pacifics (see Locobase 9389 for the saturated version), these were still small, light 4-6-2s. The refitted boiler managed the unusual feat of containing more heating surface than the earlier wet vessel. This might have reflected a relatively spread out tube arrangement in the earlier version.

H-20s were Wisconsin Central Pacifics delivered in 1909 by Alco-Schenectady; they were superheated to the same specifications as the H-1s.

Class H-1 / H-20 (Locobase 9389)

Data from Soo Miscellaneous Steam Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. Works #29908-29915, 39413-39417, 39905-39907, 42486-42491.

These were the first Pacifics for the Soo Line and as delivered they had saturated boilers. Their valve gear, located between the driver sets, operated inside piston valves measuring 12" in diameter; the latter fed relatively small cylinders.

The class was later superheated; see Locobase 8743.

Class H-2 (Locobase 1365)

Data from Soo 9 - 1943 Steam Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

These four successors to a 22-engine H-1 class featured a significantly enlarged cylinder volume, a change from Stephenson to Walschaert valve gear (still opening 12" piston valves), larger grate and firebox, a boiler pressed to a lower degree, and a more than 10% increase in adhesion. Locobase isn't sure if these were delivered with superheaters - the specifications reflect the superheated boiler. The superheater diameter is recorded as shown on the diagram; it's unusual in being 1/8" smaller than the 5 3/8", the smaller of the two diameters usually given for Schmidt Type A superheaters.

Note that the superheater area in the specs is estimated. It is a calculation based on taking the diagram value of 773 sq ft of "superheater equivalent" and deducting a third from it. See the logic presented in Locobase 1364.

Class H-22 (Locobase 9392)

Data from Soo 9 - 1943 Steam Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

Produced in February 1914, this quartet of express passenger Pacifics followed the H-3 (Locobase 7588) three years later. They shared many similarities with the earlier batch in most respects, but had a slightly smaller boiler pressed to a higher degree. Like the H-3s, they used 14" piston valves for steam admission.

Class H-23 (Locobase 3105)

Data from Soo 9 - 1943 Steam Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

These were the last 6 in a series of Pacifics built for the Minneapolis, St. Paul, and Sault Ste Marie over a 14-year period. All were relatively small engines with similar basic dimensions. The H-23s were ordered 9 years after the H-22s, which are shown in Locobase 9392.

14" piston valves and a generous lap of 1 1/8" suggest these were free steamers as does the A/S ratio. The superheater area is estimated and is 2/3 of the "equivalent" area of 1,260 shown in the diagram. See the logic explained in Locobase 1364.

Four were scrapped, one was put on display, and #2719 was being restored to operating condition in the 1990s. See http://www.2719.com from which the specifications are taken.

Class H-3 (Locobase 9393)

Data from Soo Miscellaneous Steam Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. Works numbers were 49797-49802 in May 1911 and 53134-53138 in April 1913.

By the time the 1943 Diagram book appeared, the H-3/H-21 class had been subdivided into two subgroups. The original layout, as shown in the 1913 Alco publication mentioned in Locobase 7588, showed a larger boiler than the one in the current entry. They were otherwise identical. That batch went to the Wisconsin Central.

Later differences centered on the the size of the tender; the larger version is shown in the specs.

Drury (1993) shows another group of four -- H-22 class 2714-2717 -- delivered in 1914 and weighing three tons more; see Locobase 9392.

Class H-3-21 (Locobase 7588)

Data from reproduction of 1913 Alco Bulletin 1016 on Richard Leonard's [] (accessed 16 June 2006). Works numbers were 49787-49796 in May 1911.

These locomotives represented the Soo Line subsidiary's step up into express passenger service. In addition to mounting tall-enough drivers, the design increased boiler capacity in relation to the cylinder volume as well as raising the ratio of superheater. Set to pop at 185 when first in service, the boiler's pressure setting was soon raised to 200 psi.

Another ten engines--five of which were immediately behind this batch on Schenectady's production line in 1911--had slightly smaller boilers; see Locobase 9393.

Drury (1993) shows another group of 4 -- H-22 class 2714-2717 -- delivered in 1914 and weighing three tons more; see Locobase 9392.