Southern 4-4-2 "Atlantic" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class C (Locobase 110)

Some data from Southern Railway diagrams hosted on (viewed September 2002). (Many thanks to Chris Hohl for his 22 September 2017 email reporting unlikely boiler pressure values for 177 entries. A Locobase macro caused the error .) Alco works numbers were 39318-39327.

Not considered especially brilliant engines (e.g., Roberts and Schafer in Drury (1993) called them "fleet but feeble.") The Southern built no more Atlantics. Engine #1907 was rebuilt with a superheater and piston valves (Universal steam chest type that were mounted directly on the slide valve base).

Prince (1965) confirms their relatively low pulling power by noting that after steel passenger coaches were introduced, the C class operated eastward out of Macon, Georgia to the lowland areas and such cities as Jessop and Brunswick.

NB: The direct heating surface (including the firebox heating surface) is an estimate calculated by subtracting the calculated tube heating surface from the reported total evaporative heating surface from the baldwin_steam site.

Principal Dimensions by Steve Llanso of Sweat House Media
Locobase ID110
RailroadSouthern (SRS)
Number in Class10
Road Numbers1905-1914
Number Built10
Valve GearSouthern
Locomotive Length and Weight
Driver Wheelbase (ft / m) 7.50 / 2.29
Engine Wheelbase (ft / m)29.50 / 8.99
Ratio of driving wheelbase to overall engine wheebase 0.25
Overall Wheelbase (engine & tender) (ft / m)51.30 / 15.64
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)108,000 / 48,988
Engine Weight (lbs / kg)190,000 / 86,183
Tender Loaded Weight (lbs / kg)147,000 / 66,678
Total Engine and Tender Weight (lbs / kg)337,000 / 152,861
Tender Water Capacity (gals / ML)7500 / 28.41
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)12.50 / 11.40
Minimum weight of rail (calculated) (lb/yd / kg/m)90 / 45
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)79 / 2007
Boiler Pressure (psi / kPa)200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)20.5" x 26" / 521x660
Tractive Effort (lbs / kg)23,513 / 10665.33
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.59
Heating Ability
Firebox Area (sq ft / m2)183 / 17.01
Grate Area (sq ft / m2)45 / 4.18
Evaporative Heating Surface (sq ft / m2)3113 / 289.31
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)3113 / 289.31
Evaporative Heating Surface/Cylinder Volume313.42
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation9000
Same as above plus superheater percentage9000
Same as above but substitute firebox area for grate area36,600
Power L110,679
Power MT435.98

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Wes Barris