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 ID13,235
RailroadInterstate (IRR)
Number in Class1
Road Numbers9
Number Built1
Valve GearSouthern
Locomotive Length and Weight
Driver Wheelbase (ft) 6.50
Engine Wheelbase (ft)27.25
Ratio of driving wheelbase to overall engine wheebase 0.24
Overall Wheelbase (engine & tender) (ft)56.10
Axle Loading (Maximum Weight per Axle) (lbs)
Weight on Drivers (lbs)100,000
Engine Weight (lbs)181,000
Tender Loaded Weight (lbs)115,000
Total Engine and Tender Weight (lbs)296,000
Tender Water Capacity (gals)6000
Tender Fuel Capacity (oil/coal) (gals/tons)12
Minimum weight of rail (calculated) (lb/yd)83
Geometry Relating to Tractive Effort
Driver Diameter (in)66
Boiler Pressure (psi)200
High Pressure Cylinders (dia x stroke) (in)20" x 26"
Tractive Effort (lbs)26,788
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.73
Heating Ability
Firebox Area (sq ft)208
Grate Area (sq ft)49.50
Evaporative Heating Surface (sq ft)2672
Superheating Surface (sq ft)
Combined Heating Surface (sq ft)2672
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 area41,600
Power L18638
Power MT380.87

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