Interstate 4-4-2 "Atlantic" Locomotives in 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.

Principal Dimensions 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 / m) 6.50 / 1.98
Engine Wheelbase (ft / m)27.25 / 8.31
Ratio of driving wheelbase to overall engine wheebase 0.24
Overall Wheelbase (engine & tender) (ft / m)56.10 / 17.10
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)100,000 / 45,359
Engine Weight (lbs / kg)181,000 / 82,100
Tender Loaded Weight (lbs / kg)115,000 / 52,163
Total Engine and Tender Weight (lbs / kg)296,000 / 134,263
Tender Water Capacity (gals / ML)6000 / 22.73
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)12 / 10.90
Minimum weight of rail (calculated) (lb/yd / kg/m)83 / 41.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)66 / 1676
Boiler Pressure (psi / kPa)200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)20" x 26" / 508x660
Tractive Effort (lbs / kg)26,788 / 12150.85
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.73
Heating Ability
Firebox Area (sq ft / m2)208 / 19.32
Grate Area (sq ft / m2)49.50 / 4.60
Evaporative Heating Surface (sq ft / m2)2672 / 248.23
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)2672 / 248.23
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

All material Copyright ©
Wes Barris