Chesapeake & Ohio 4-4-2 "Atlantic" Type Locomotives

Class A-16 (Locobase 5047)

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 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
Class	A-16	A-16s
Locobase ID	5047	5048
Railroad	Chesapeake & Ohio (C & O)	Chesapeake & Ohio (C & O)
Whyte	4-4-2	4-4-2
Road Numbers	275-294	275-294
Gauge	Std	Std
Builder	Alco	Alco
Year	1902	1902
Valve Gear	Stephenson	Walschaert
	Locomotive Length and Weight
Driver Wheelbase	7'	7'
Engine Wheelbase		27.92'
Ratio of driving wheelbase to overall engine wheebase		0.25
Overall Wheelbase (engine & tender)		57.04'
Axle Loading (Maximum Weight per Axle)		58500 lbs
Weight on Drivers	84000 lbs	113500 lbs
Engine Weight	156000 lbs	199500 lbs
Tender Light Weight		136310 lbs
Total Engine and Tender Weight	290250 lbs	335810 lbs
Tender Water Capacity		7000 gals
Tender Fuel Capacity (oil/coal)		12.5 tons
Minimum weight per yard of rail on which locomotive could run	70 lb rail	95 lb rail
	Geometry Relating to Tractive Effort
Driver Diameter	72"	73"
Boiler Pressure	200 psi	185 psi
Cylinders (dia x stroke)	21" x 26"	22" x 26"
Tractive Effort	27073 lbs	27107 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort)	3.10	4.19
	Heating Ability
Firebox Area	201 sq. ft	201 sq. ft
Grate Area	50 sq. ft	50.20 sq. ft
Evaporative Heating Surface	3318	2470
Superheating Surface		480
Combined Heating Surface	3318	2950
Evaporative Heating Surface/Cylinder Volume	318.34	215.92
	Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation	10000	9287
Same as above plus superheater percentage	10000	11144
Same as above but substitute firebox area for grate area	40200	44622
Power L1	9954	15338
Power MT	522.49	595.85