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 ID14,331 7626
RailroadSierra RailwaySierra Railway
Number in Class11
Road Numbers3032/132
Number Built11
Valve GearWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft) 9.179
Engine Wheelbase (ft)23.7524.50
Ratio of driving wheelbase to overall engine wheebase 0.39 0.37
Overall Wheelbase (engine & tender) (ft)46.2146.96
Axle Loading (Maximum Weight per Axle) (lbs)27,700
Weight on Drivers (lbs)78,00083,100
Engine Weight (lbs)98,000106,200
Tender Loaded Weight (lbs)63,10063,000
Total Engine and Tender Weight (lbs)161,100169,200
Tender Water Capacity (gals)30003000
Tender Fuel Capacity (oil/coal) (gals/tons)10001000
Minimum weight of rail (calculated) (lb/yd)4346
Geometry Relating to Tractive Effort
Driver Diameter (in)4246
Boiler Pressure (psi)175180
High Pressure Cylinders (dia x stroke) (in)15" x 24"16" x 24"
Tractive Effort (lbs)19,12520,435
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.08 4.07
Heating Ability
Firebox Area (sq ft)8693
Grate Area (sq ft)14.1017.90
Evaporative Heating Surface (sq ft)8321114
Superheating Surface (sq ft)178241
Combined Heating Surface (sq ft)10101355
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 area17,75919,753
Power L171479261
Power MT606.02737.08

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