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.
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.
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 outside 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.
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.
Data from "Tank Locomotive; Central Pacific Railroad", Engineering, Volume 34 This (18 August 1882), p. 155.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.  (visited 6 January 2005), this class of little tanks operated into the 'Teens. One (335, works #18) was sold to the Tidewater Southern in 1912, which 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.
|Principal Dimensions by Steve Llanso of Sweat House Media|
|Class||PR-3||Pr-1||Pr-1/Pr-2 - superheated||Pr-2||S-1|
|Railroad||California Northwestern (SP)||El Paso & Northeastern (SP)||El Paso & Northeastern (SP)||El Paso & Northeastern (SP)||Central Pacific (SP)|
|Number in Class||2||4||4||2||7|
|Road Numbers||33-34/201-202||20-23||134-139/1900-1905||24-25 / 138-139||230-236/1501-1507/1900-1906|
|Builder||Burnham, Williams & Co||Burnham, Williams & Co||EP&NE||Burnham, Williams & Co||Central Pacific|
|Locomotive Length and Weight|
|Driver Wheelbase (ft / m)||8.33 / 2.54||13.33 / 4.06||13.33 / 4.06||13.33 / 4.06||14 / 4.27|
|Engine Wheelbase (ft / m)||22.50 / 6.86||31.50 / 9.60||31.50 / 9.60||31.50 / 9.60||28 / 8.53|
|Ratio of driving wheelbase to overall engine wheebase||0.37||0.42||0.42||0.42||0.50|
|Overall Wheelbase (engine & tender) (ft / m)||22.50 / 6.86||58.96 / 17.97||58.96 / 17.97||28|
|Axle Loading (Maximum Weight per Axle) (lbs / kg)|
|Weight on Drivers (lbs / kg)||84,000 / 38,102||125,190 / 56,785||136,800 / 62,052||125,190 / 56,785||80,400 / 36,469|
|Engine Weight (lbs / kg)||117,100 / 53,116||183,865 / 83,400||200,500 / 90,945||183,865 / 83,400||104,100 / 47,219|
|Tender Loaded Weight (lbs / kg)||116,135 / 52,678||116,135 / 52,678|
|Total Engine and Tender Weight (lbs / kg)||117,100||300,000 / 136,078||300,000 / 136,078||104,100|
|Tender Water Capacity (gals / ML)||6000 / 22.73||7000 / 26.52||1280 / 6.06|
|Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)||10 / 9.10||10||4 / 3.60|
|Minimum weight of rail (calculated) (lb/yd / kg/m)||47 / 23.50||70 / 35||76 / 38||70 / 35||45 / 22.50|
|Geometry Relating to Tractive Effort|
|Driver Diameter (in / mm)||47 / 1194||69 / 1753||70 / 1778||69 / 1753||50 / 1295|
|Boiler Pressure (psi / kPa)||160 / 11||180 / 12.40||170 / 11.70||180 / 12.40||125 / 10|
|High Pressure Cylinders (dia x stroke) (in / mm)||17" x 22" / 432x559||21" x 28" / 533x711||23" x 28" / 584x711||21" x 28" / 533x711||16" x 24" / 406x610|
|Tractive Effort (lbs / kg)||18,398 / 8345.20||27,380 / 12419.37||30,576 / 13869.06||27,380 / 12419.37||13,056 / 5922.11|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||4.57||4.57||4.47||4.57||6.16|
|Firebox Area (sq ft / m2)||91.60 / 8.51||188.30 / 17.49||188 / 17.47||185 / 17.19||88|
|Grate Area (sq ft / m2)||14.40 / 1.34||53.50 / 4.97||53.90 / 5.01||53.40 / 4.96||14.70|
|Evaporative Heating Surface (sq ft / m2)||1099 / 102.10||3520 / 327.02||2669 / 248.05||3516 / 326.64||929|
|Superheating Surface (sq ft / m2)||494 / 45.91|
|Combined Heating Surface (sq ft / m2)||1099 / 102.10||3520 / 327.02||3163 / 293.96||3516 / 326.64||929|
|Evaporative Heating Surface/Cylinder Volume||190.15||313.60||198.23||313.24||166.34|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||2304||9630||9163||9612||1838|
|Same as above plus superheater percentage||2304||9630||10,629||9612||1838|
|Same as above but substitute firebox area for grate area||14,656||33,894||37,074||33,300||11,000|