2-6-2 "Prairie" Steam Locomotives in the USA

Class HA/S-1 (Locobase 2846)

Data from "Tank Locomotive; Central Pacific Railroad", Engineering, Volume 34 This (18 August 1882), p. 155. See also

[] (visited 6 January 2005); and David L Joslyn, "The Old Class HA Locomotives of the Central Pacific." The Railway and Locomotive Historical Society Bulletin, no. 91 (1954): 122-24. [] . Master Mechanic AJ Stevens designed this engine for the heavy suburban traffic out of Oakland and Alameda, Calif. Engineering reported that the route was short (3 to 8 miles) from the end of the ferry wharf some two miles into San Francisco Bay. But morning and evening trains were "very heavy and make frequent stops." Note the very high factor of adhesion, which suggests an underexploited boiler.

As Joslyn tells the story: "Chief Draftsman George Stoddart received the following guidance from General Master Mechanic A J Stevens: "What is needed is a locomotive that ill be powerful enough to handle the traffic; that will be flexible enough to take the curves and fairly high speed; one that can start and pick up speed rapidly; and one that can operate in either direction without having to be turned."

Stevens's accompanying sketch showed valves that "would admit steam quickly, and just as quickly let the exhaust out of the cylinders, thereby reducing back-pressure to a minimum.". Stoddard apparenly found the traditional Williams-Howe internal link motion would be adequately.

The required capabilities match up with practice in the British Isles, which produced hundreds of such engines over decades. One key innovation concerned the wheel arrangement, the first examples of what would become known as the Prairie type. It added the extra adhesion that typical 2-4-2 and 2-4-4 tanks couldn't offer The valve design featured valves at each end of the cylinder; presumably one valve admitted steam while the other valve exhausted it. At first, the class used the typical CP diamond stack that used a cast iron deflector and water wheel cone to set sparks whirling downward.

Delivered in 1881 (1) and 1882 (6), the septet immediately proved successful, serving "Oakland local trains in fine shape." In the early 1890s, the class received new fireboxes and new front tubesheets along with an extended smokebox and straight stacks. Almost immediately, the shops converted the firebox to burn crude oil stored in a 800 US gallon (3,028 litres) tank behind the cab .

[] (visited 6 January 2005), this class of little tanks operated into the 'Teens. The SP repurposed three of the S-1s (1900-1901,1906) as shop switchers.

Three of the remaining four went to new owners in 1912.

The Tidewater Southern operated it between Modesto and the Stanilaus River and later to Stockton until the TS was electrified. At that point, the TS sold it to the Howard Terminal in Oakland in 1917.

NB Livermore bought 1902 and Shattuck & Edinger purchased 1904 as their #8.

A "logging company" bought 1903 in August 1914.

Class PR-3 (Locobase 8173)

Data from the NWP 10 - 1950 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See the excellent roster on [], access 9 February 2007. See also DeGolyer, Volume 25, p. 296. Works numbers were 22446 and 22474 in July 1903.

Although often described as "Prairie Tanks", this pair can lay only a small claim to that characterisation. The diagram's outline suggests that this was a Mogul tank with a trailing axle added to hold up the bunker. Baldwin delivered them separately to the California Northwestern as 33-34. Operating in the Redwood Empire, the two engines were med with 4% grades and 30 deg curves.

Both of these engines were sold to the Northwestern Pacific in January 1907 and renumbered 201-202. The NWP scrapped the 201 in January 1930 and sold the 202 in October 1937.

Class Pr-1 (Locobase 10785)

Data from Baldwin Locomotive Works, Record of Recent Construction ((1903), No. 39, p. 256-257. See also "El Paso-Rock Island Locomotives", Railway Age, Volume 34 (31 Ocotober 1902), pp. 458-459; and DeGolyer, Volume 25, p. 44.. Works numbers were 20999, 21024, and 21036-21037 in September 1902.

The only set of Prairies to operate for an Espee line, this quartet was produced for the EP&NE (described on the tender sides as the "El Paso-Rock Island Route") in single units, then a set of twins in 1902. In noting that the weight on the Rushton trailing trruck shouldn't exceed 42,000 lb (19,051 kg), the Baldwin spec includes an "oh, by the way" accounting of the operating environment:"Hilly road, bad water, poor fuel, light rails, much of it only 60 lb[/yard; 30 kg/metre]". One can see the attraction of a passenger engine with a trailing truck in the growth in grate area.

The EP&NE added two more in September 1904 as class Pr-2; see Locobase 13635

The class soon came under the El Paso & Southwestern when that railroad bought the EP&NE in 1905 and were renumbered 134-137. At some later date, the quartet was superheated; see Locobase 8671.

Class Pr-1/Pr-2 - superheated (Locobase 8671)

Data from SP 7 - 1951 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

Entering service on the El Paso & Northeastern with saturated boilers (Locobase 10785 and 13635), these Prairies were superheated relatively early, receiving the units between February 1912 and June 1913. In the process, they acquired constant-lead radial valve gear, cylinders with 2" (50.8 mm) greater diameter, but less heating surface and lower boiler pressure.

They wore the EP&SW herald until the Southern Pacific bought the EP&SW in 1925. At that point they were assigned to the Southern Pacific de Mexico as 700-703, where, except for the 703, they ran until scrapping in 1934-1935. 703 had one more stop to make. Modified for oil-burning and re-re-numbered 1903, this engine operated on Bay Area commuter lines until 1934.

The later two engines--1905, 1904--remained with the SP until they were scrapped in June 1934 and March 1936, respectively.

Class Pr-2 (Locobase 13635)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University, Volume 27, p. 99. (Thanks to Chris Hohl for his 11 August 2017 email supplying the coal capacity.) Works numbers were 24657-24658 in September 1904.

Two years after the first Prairies came to the EP&NE (Locobase 10785), Baldwin added two more with slight differences. Like the Pr-1s, they were superheated; see Locobase 8671.