California Northwestern / El Paso & Northeastern 2-6-2 "Prairie" Locomotives of the USA

Class Details by Steve Llanso of Sweat House Media

Class PR-3 (Locobase 8173)

Data from the NWP 10 - 1950 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive Raildata collection. 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. 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 in single units fin 1902. 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 Raildata collection.

Entering service on the El Paso & Northeastern with saturated boilers (Locobase 10785), this quartet was superheated relatively early, receiving the units between February 1912 and June 1913. In the process, they acquired outside radial valve gear, cylinders with 2" 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.

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. Works numbers were 24657-24658 in September 1904.

Two years after the first Prairies came to the EP & NE (Locobase 10785), Baldwin added 2 more with slight differences. Like the Pr-1s, t was superheated; see Locobase 8671.

Specifications by Steve Llanso of Sweat House Media
ClassPR-3Pr-1Pr-1/Pr-2 - superheatedPr-2
Locobase ID8173 10785 8671 13635
RailroadCalifornia Northwestern (SP)El Paso & Northeastern (SP)El Paso & Northeastern (SP)El Paso & Northeastern (SP)
Number in Class2442
Road Numbers33-34/201-20220-23134-39/ 1900-190524-25 / 138-139
Number Built242
BuilderBurnham, Williams & CoBurnham, Williams & CoEP&NEBurnham, Williams & Co
Valve GearStephensonStephensonWalschaertStephenson
Locomotive Length and Weight
Driver Wheelbase 8.33'13.33'13.33'13.33'
Engine Wheelbase22.50'31.50'31.50'31.50'
Ratio of driving wheelbase to overall engine wheebase 0.37 0.42 0.42 0.42
Overall Wheelbase (engine & tender)22.50'58.96'58.96'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers84000 lbs125190 lbs136800 lbs125190 lbs
Engine Weight117100 lbs183865 lbs200500 lbs183865 lbs
Tender Light Weight116135 lbs116135 lbs
Total Engine and Tender Weight117100 lbs300000 lbs300000 lbs
Tender Water Capacity6000 gals7000 gals
Tender Fuel Capacity (oil/coal)
Minimum weight of rail (calculated)47 lb/yard70 lb/yard76 lb/yard70 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter47"69"70"69"
Boiler Pressure160 psi180 psi170 psi180 psi
Cylinders (dia x stroke)17" x 22"21" x 28"23" x 28"21" x 28"
Tractive Effort18398 lbs27380 lbs30576 lbs27380 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.57 4.57 4.47 4.57
Heating Ability
Firebox Area91.60 sq. ft188.30 sq. ft188 sq. ft185 sq. ft
Grate Area14.40 sq. ft53.50 sq. ft53.90 sq. ft53.40 sq. ft
Evaporative Heating Surface1099 sq. ft3520 sq. ft2669 sq. ft3516 sq. ft
Superheating Surface494 sq. ft
Combined Heating Surface1099 sq. ft3520 sq. ft3163 sq. ft3516 sq. ft
Evaporative Heating Surface/Cylinder Volume190.15313.60198.23313.24
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation2304963091639612
Same as above plus superheater percentage23049630106299612
Same as above but substitute firebox area for grate area14656338943707433300
Power L133768228118658190
Power MT265.81434.69573.64432.68



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