Tennessee Central 4-8-2 "Mountain" Locomotives of the USA

The Tennessee Central Mountains were the third lightest of the type (behind Alaska Railroad and New Orleans Great Northern).

Roster by Richard Duley

CNRoad NumbersYear BuiltBuilder

Class Details by Steve Llanso of Sweat House Media

Class 551 (Locobase 7347)

Data from TC 1941ca Locomotive Diagrams and Miscellaneous Data supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

Locobase is intrigued by the unusual boiler pressure rating in these small Mountains. 213 psi converts to 15 bar (or atm), a unit of measure that was almost never used in North American railroading. In any event, these were small for their arrangement and had very low drivers, which suited the hilly terrain over which the class operated. They may have been the lightest 4-8-2s operating on the standard gauge anywhere in North America.

Specifications by Steve Llanso of Sweat House Media
Locobase ID7347
RailroadTennessee Central
Number in Class4
Road Numbers551-554
Number Built4
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase16.75'
Engine Wheelbase37'
Ratio of driving wheelbase to overall engine wheebase 0.45
Overall Wheelbase (engine & tender)69.94'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers180500 lbs
Engine Weight273000 lbs
Tender Light Weight158800 lbs
Total Engine and Tender Weight431800 lbs
Tender Water Capacity9000 gals
Tender Fuel Capacity (oil/coal)14 tons
Minimum weight of rail (calculated)75 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter63"
Boiler Pressure217.60 psi
Cylinders (dia x stroke)24" x 28"
Tractive Effort47350 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.81
Heating Ability
Firebox Area234 sq. ft
Grate Area59.95 sq. ft
Evaporative Heating Surface2795 sq. ft
Superheating Surface752 sq. ft
Combined Heating Surface3547 sq. ft
Evaporative Heating Surface/Cylinder Volume190.64
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation13045
Same as above plus superheater percentage15785
Same as above but substitute firebox area for grate area61611
Power L116727
Power MT817.21

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