Utah Railway 2-8-8-0 "Consolidation Mallet" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class 200 (Locobase 9496)

Data from "Mallet Locomotives for the Utah Railway," Railway and Locomotive Engineering, February 1919, p.39. See also DeGolyer, Volume 56, pp. 249+. Works numbers were 48221-48222 in April 1918 and 48901 in June.

Virtually identical to the B&O ELs shown in Locobase 439, this trio went to the United States Smelting company for them to operate on the UR. One small difference was the UR engines' use of 1" smaller diameter drivers to conquer grades of up to 2.4%. The Mallet layout contributed to an ability to negotiate 20-deg curves in sidings and 9-deg curves on the main line.

All four cylinders were supplied through 15" (381 mm) piston valves. Firebox heating surface area included 43 sq ft (4.0 sq m) in four arch tubes and 118 sq ft (10.96 sq m) from the combustion chamber.

The article noted another feature of use in the Utah Railway's winding surroundings: "The Baldwin design of flexible articulated frame connection is used. With this construction, the front and rear frames can move relatively to each other in a vertical plane, without causing binding at the hinge pin. The value of this feature is specially noticeable in a Mallet locomotive with long wheelbase, when passing over uneven tracks or sudden changes in grade."

The design proved successful enough to endure into the 1950s with two of the engines leaving service in 1954 and the third (201) as late as March 1957.

Principal Dimensions by Steve Llanso of Sweat House Media
Locobase ID9496
RailroadUtah Railway
Number in Class3
Road Numbers200-202
Number Built3
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)15.50 / 4.72
Engine Wheelbase (ft / m)50.33 / 15.34
Ratio of driving wheelbase to overall engine wheebase 0.31
Overall Wheelbase (engine & tender) (ft / m)88.50 / 26.97
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)452,300 / 205,160
Engine Weight (lbs / kg)476,300 / 216,046
Tender Loaded Weight (lbs / kg)215,700 / 97,840
Total Engine and Tender Weight (lbs / kg)692,000 / 313,886
Tender Water Capacity (gals / ML)12,000 / 45.45
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)20 / 18.20
Minimum weight of rail (calculated) (lb/yd / kg/m)94 / 47
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)57 / 1448
Boiler Pressure (psi / kPa)210 / 14.50
High Pressure Cylinders (dia x stroke) (in / mm)26" x 32" / 660x813
Low Pressure Cylinders (dia x stroke) (in / mm)41" x 32" / 1041x813
Tractive Effort (lbs / kg)96,627 / 43829.32
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.68
Heating Ability
Firebox Area (sq ft / m2)392 / 36.43
Grate Area (sq ft / m2)88.20 / 8.20
Evaporative Heating Surface (sq ft / m2)5835 / 542.29
Superheating Surface (sq ft / m2)1446 / 134.39
Combined Heating Surface (sq ft / m2)7281 / 676.68
Evaporative Heating Surface/Cylinder Volume296.73
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation18,522
Same as above plus superheater percentage22,226
Same as above but substitute firebox area for grate area98,784
Power L18490
Power MT331.06