Interstate 4-4-2 "Atlantic" Locomotives of the USA

Class Details by Steve Llanso of Sweat House Media

Class 9 (Locobase 13235)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University, Volume 53, pp. 259. Works number was 44660 in December 1916.

Five years after Baldwin had delivered its last Atlantic to a Southern Pacific subsidiary, this Virginia shortline coal road ordered one. It had a large grate, firebox with 21 sq ft (1.95 sq m) of arch tubes, and a saturated boiler. It rolled on 80 lb/yard (40 kg/metre) rail.

Likely because it couldn't afford to waste any equipment it had already paid for, the IRR didn't retire this single passenger engine until 1939.

Specifications by Steve Llanso of Sweat House Media
Locobase ID13235
RailroadInterstate (IRR)
Number in Class1
Road Numbers9
Number Built1
Valve GearSouthern
Locomotive Length and Weight
Driver Wheelbase 6.50'
Engine Wheelbase27.25'
Ratio of driving wheelbase to overall engine wheebase 0.24
Overall Wheelbase (engine & tender)56.10'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers100000 lbs
Engine Weight181000 lbs
Tender Light Weight115000 lbs
Total Engine and Tender Weight296000 lbs
Tender Water Capacity6000 gals
Tender Fuel Capacity (oil/coal)12 tons
Minimum weight of rail (calculated)83 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter66"
Boiler Pressure200 psi
Cylinders (dia x stroke)20" x 26"
Tractive Effort26788 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.73
Heating Ability
Firebox Area208 sq. ft
Grate Area49.50 sq. ft
Evaporative Heating Surface2672 sq. ft
Superheating Surface
Combined Heating Surface2672 sq. ft
Evaporative Heating Surface/Cylinder Volume282.64
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation9900
Same as above plus superheater percentage9900
Same as above but substitute firebox area for grate area41600
Power L18638
Power MT380.87

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