Chattanooga Union 2-4-4 Locomotives of the USA

Class Details by Steve Llanso of Sweat House Media

Class 20 (Locobase 11605)

Data from Baldwin Locomotive Works Specification for Engines, 188, as digitized by the DeGolyer Library of Southern Methodist University Vol 15, p. 51. Works numbers 9248 in May 1888 and 9923 in April 1889.

This belt lined encircled Chattanooga in a 50-mile loop that had branches shooting off to the major Civil War battlesights at Lookout Mountain and east of the river. These tank engines lent their energies to passenger service on the street-railway portion. Although Connelly shows the pair with a single-axle trailing truck and 48" drivers, the original specs called for a bogie trailing truck and 46" wheels.

As with many street railways, steam traction was soon supplanted by electric power and the 22 went off to the Jackson Railroad in 1895 while the 20 was sold to Ducktown Sulpher, Copper & Iron Company in 1902.

Specifications by Steve Llanso of Sweat House Media
Locobase ID11,605
RailroadChattanooga Union
Number in Class2
Road Numbers20, 22
Number Built2
BuilderBurnham, Williams & Co
Valve GearStephenson
Locomotive Length and Weight
Driver Wheelbase (ft) 6.50
Engine Wheelbase (ft)25.75
Ratio of driving wheelbase to overall engine wheebase 0.25
Overall Wheelbase (engine & tender) (ft)25.75
Axle Loading (Maximum Weight per Axle) (lbs)
Weight on Drivers (lbs)38,000
Engine Weight (lbs)65,000
Tender Loaded Weight (lbs)
Total Engine and Tender Weight (lbs)65,000
Tender Water Capacity (gals)300
Tender Fuel Capacity (oil/coal) (gals/tons)
Minimum weight of rail (calculated) (lb/yd)32
Geometry Relating to Tractive Effort
Driver Diameter (in)46
Boiler Pressure (psi)130
High Pressure Cylinders (dia x stroke) (in)12" x 20"
Tractive Effort (lbs)6918
Factor of Adhesion (Weight on Drivers/Tractive Effort) 5.49
Heating Ability
Firebox Area (sq ft)
Grate Area (sq ft)12.70
Evaporative Heating Surface (sq ft)
Superheating Surface (sq ft)
Combined Heating Surface (sq ft)
Evaporative Heating Surface/Cylinder Volume
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation1651
Same as above plus superheater percentage1651
Same as above but substitute firebox area for grate area
Power L1
Power MT

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