Chesapeake & Ohio 4-4-2 "Atlantic" Locomotives of the USA

Class Details by Steve Llanso of Sweat House Media

Class A-16 (Locobase 5047)

Data from "Atlantic Type for the C & O," Railway & Locomotive Engineering, Vol 15,(November 1902), p. 464

Firebox heating surface included 27.09 sq ft of water tubes. The design featured a "traction increaser" that could be applied to put an additional 12,000 lb on the drivers. The cab had the typical C & O clerestory on top.

The only Atlantics on the Chesapeake and Ohio. The wheel arrangement may not seem the best choice for the line's profile and indeed these were the only 4-4-2s. But they held on for decades in their superheated form. (See 5048).

Class A-16s (Locobase 5048)

Beginning with the last of the class, the Chessie's Atlantics were made over in the early 1920s. 278 was delivered in 1916 as shown above in the specs -- the other 19 were modified to match. Data from C & O's 1936 Locomotive Diagram book supplied by Allen Stanley in May 2005 from his extensive Raildata collection.

Notice the choices made in the renovation. Tractive effort remained nearly identical because at the same time the cylinders gained a inch in diameter, the boiler pressure was knocked down 15 psi. Piston valves measured a healthy 12" in diameter. Weights increased considerably. Overall heating surface declined, but having 16.3% in superheater area could only improve efficiency. Firebox heating surface includes 23 sq ft in 4 arch tubes.

The makeover must have been satisfactory as 13 of the engines remained in use until 1949

Specifications by Steve Llanso of Sweat House Media
Locobase ID5047 5048
RailroadChesapeake & Ohio (C&O)Chesapeake & Ohio (C&O)
Number in Class2020
Road Numbers275-294275-294
Number Built20
Valve GearStephensonWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft)77
Engine Wheelbase (ft)27.5027.92
Ratio of driving wheelbase to overall engine wheebase 0.25 0.25
Overall Wheelbase (engine & tender) (ft)55.2957.04
Axle Loading (Maximum Weight per Axle) (lbs)58,500
Weight on Drivers (lbs)93,000113,500
Engine Weight (lbs)173,000199,500
Tender Loaded Weight (lbs)136,310
Total Engine and Tender Weight (lbs)335,810
Tender Water Capacity (gals)60007000
Tender Fuel Capacity (oil/coal) (gals/tons)912.50
Minimum weight of rail (calculated) (lb/yd)7895
Geometry Relating to Tractive Effort
Driver Diameter (in)7273
Boiler Pressure (psi)200185
High Pressure Cylinders (dia x stroke) (in)21" x 26"22" x 26"
Tractive Effort (lbs)27,07327,107
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.44 4.19
Heating Ability
Firebox Area (sq ft)207.79201
Grate Area (sq ft)50.3250.20
Evaporative Heating Surface (sq ft)35062470
Superheating Surface (sq ft)480
Combined Heating Surface (sq ft)35062950
Evaporative Heating Surface/Cylinder Volume336.38215.92
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation10,0649287
Same as above plus superheater percentage10,06410,773
Same as above but substitute firebox area for grate area41,55843,135
Power L110,46515,338
Power MT496.16595.85


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