USRA 4-8-2 "Mountain" Type Locomotives

Class Heavy (Locobase 232)

Data from tables in 1930 Locomotive Cyclopedia. See also (see Locobase 232). See also Robert A LeMassena, "The USRA HEAVY 4-8-2 and its Illustrious Ascendants", Railway & Locomotive Historical Society Newsletter (Vol 23, #2 - Spring 2003).

Boiler had feedwater heater. Only 15 "Heavy" mountains entered service under the USRA aegis. Baldwin built two engines for the C&O, Alco-Brooks supplied three more to the C&O as well as 10 more to the N&W. LeMassena argues, however, that this particular design influenced not only 4-8-2 designs, but also encouraged the development of the larger 4-8-4.

Class Light (Locobase 231)

Boiler had feedwater heater.

Standard light "Mountain" design as conceived for mass production during World War I. Four railroads bought 47 locomotives, 25 going to the Southern. Baldwin built 15 (for the Southern), Alco-Richmond supplied 15, and Alco-Schenectady delivered 17 to the MoPac and the Southern. Most later Mountains had a higher superheater to evaporative heating surface ratio and a higher boiler pressure.

Specifications
ClassHeavyLight
Locobase ID232231
RailroadUSRAUSRA
Whyte4-8-24-8-2
Road Numbers1000010000
GaugeStdStd
BuilderSeveralSeveral
Year19181918
Valve GearBakerBaker
Locomotive Length and Weight
Driver Wheelbase18.25'18.25'
Engine Wheelbase40'40'
Ratio of driving wheelbase to overall engine wheebase 0.46 0.46
Overall Wheelbase (engine & tender)75.70'75.70'
Axle Loading (Maximum Weight per Axle)56500 lbs
Weight on Drivers243000 lbs224500 lbs
Engine Weight352500 lbs327000 lbs
Tender Light Weight194200 lbs193700 lbs
Total Engine and Tender Weight546700 lbs520700 lbs
Tender Water Capacity10000 gals10000 gals
Tender Fuel Capacity (oil/coal)16 tons16 tons
Minimum weight per yard of rail on which locomotive could run101.25 lb rail93.54 lb rail
Geometry Relating to Tractive Effort
Driver Diameter69"69"
Boiler Pressure200 psi200 psi
Cylinders (dia x stroke)28" x 30"27" x 30"
Tractive Effort57948 lbs53883 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.19 4.17
Heating Ability
Firebox Area373 sq. ft348 sq. ft
Grate Area76.30 sq. ft70.30 sq. ft
Evaporative Heating Surface46664121
Superheating Surface1085966
Combined Heating Surface57515087
Evaporative Heating Surface/Cylinder Volume218.24207.29
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation1526014060
Same as above plus superheater percentage18138.9916729.94
Same as above but substitute firebox area for grate area88674.2582816.75
Power L117530.5416838.95
Power MT636.18661.44

Credits

Introduction and specifications provided by Steve Llanso of Sweat House Media.