Sierra Railway 2-6-2 "Prairie" Locomotives of the USA

Class Details by Steve Llanso of Sweat House Media

Class 30 (Locobase 14331)

Data from DeGolyer, Vol 65, pp. 255+. Works number was 55412 in May 1922.

The SRwy superheated most of its engines, even the small logging Prairies that roamed the back country of the Sierra Nevada. The 30 had to tread lightly: it rolled on 40 lb/yard (20 kg/metre) rail, up 4% grades, and contorted its trains around 45 degree curves.

After 15 years with the SRR, the 30 was sold in March 1937 to Howard Terminal in Oakland, Calif, and converted to a 2-6-2T.

Class 32/TF-20 (Locobase 7626)

Data from WP 2 - 1946 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection. See also DeGolyer, Volume 71, pp. 170. (Thanks to Chris Hohl for his 26 November 2015 emails supplying the tender capacities and weights as built.) Works number was 57018 in September 1923.

Unusual Prairie that operated in the California mountains on this logging railroad's Angels Camp branch. Its piston valves measured 8" (203 mm) in diameter.

In 1940, the Western Pacific bought the little mountaineer to operate on its Tidewater Southern subsidiary; at that point, the tender's capacities had increased to 3,760 US gallons (14,232 litres) and 1,500 gallons (5,678 litres) of oil and weighed 78,526 lb (35,619 kg). The Tidewater Southern website --, accessed 3 July 2006, believes the 132 was the last steamer to operate in revenue service on the WP's lines.

Specifications by Steve Llanso of Sweat House Media
Locobase ID14331 7626
RailroadSierra RailwaySierra Railway
Number in Class11
Road Numbers3032/132
Number Built11
Valve GearWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase 9.17'9'
Engine Wheelbase23.75'24.50'
Ratio of driving wheelbase to overall engine wheebase 0.39 0.37
Overall Wheelbase (engine & tender)46.21'46.96'
Axle Loading (Maximum Weight per Axle)27700 lbs
Weight on Drivers78000 lbs83100 lbs
Engine Weight98000 lbs106200 lbs
Tender Light Weight63100 lbs63000 lbs
Total Engine and Tender Weight161100 lbs169200 lbs
Tender Water Capacity3000 gals3000 gals
Tender Fuel Capacity (oil/coal)1000 gals1000 gals
Minimum weight of rail (calculated)43 lb/yard46 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter42"46"
Boiler Pressure175 psi180 psi
Cylinders (dia x stroke)15" x 24"16" x 24"
Tractive Effort19125 lbs20435 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.08 4.07
Heating Ability
Firebox Area86 sq. ft93 sq. ft
Grate Area14.10 sq. ft17.90 sq. ft
Evaporative Heating Surface832 sq. ft1114 sq. ft
Superheating Surface178 sq. ft241 sq. ft
Combined Heating Surface1010 sq. ft1355 sq. ft
Evaporative Heating Surface/Cylinder Volume169.49199.46
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation24683222
Same as above plus superheater percentage29123802
Same as above but substitute firebox area for grate area1775919753
Power L171479261
Power MT606.02737.08

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