Chicago, Indianapolis & Louisville 4-4-2 "Atlantic" Locomotives of the USA

Class Details by Steve Llanso of Sweat House Media

Class I-1 (Locobase 7088)

Data from C I & L 1 - 1940 locomotive diagram supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

Just two Atlantics were ever delivered to the Monon. They were middle-of-the-pack engines that endured for more than three decades. They were superheated in the 1920s (Locobase 8314).

"Monon" is the common name for the Chicago, Indianopolis, and Louisville Railroad.

Class I-1-A (Locobase 8314)

Data from C I & L 8 - 1941 locomotive diagram supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

According to Drury (1993), the two Monon Atlantics (Locobase 7088) were retrofitted with Baker valve gear at the same time the piston valves were moved outside and the inboard-bearing trailing truck was replaced with a cast truck using outside bearings. But the C I & L's diagram shows Walschaert gear. Superheating the boiler and adding some direct heating surface area to the firebox (probably in the form of arch tubes) signficantly increased available power without sacrificing too much grip on the rail.

Even so, heavier passenger trains doomed this pair to retirement in 1936.

Specifications by Steve Llanso of Sweat House Media
Locobase ID7088 8314
RailroadChicago, Indianapolis & Louisville (Monon)Chicago, Indianapolis & Louisville (Monon)
Number in Class22
Road Numbers390-391390-391
Number Built2
Valve GearStephensonWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft)77
Engine Wheelbase (ft)28.7128.25
Ratio of driving wheelbase to overall engine wheebase 0.24 0.25
Overall Wheelbase (engine & tender) (ft)56.4659.25
Axle Loading (Maximum Weight per Axle) (lbs)
Weight on Drivers (lbs)92,50095,000
Engine Weight (lbs)167,300177,100
Tender Loaded Weight (lbs)162,000152,000
Total Engine and Tender Weight (lbs)329,300329,100
Tender Water Capacity (gals)74007400
Tender Fuel Capacity (oil/coal) (gals/tons)1813
Minimum weight of rail (calculated) (lb/yd)7779
Geometry Relating to Tractive Effort
Driver Diameter (in)7373
Boiler Pressure (psi)200200
High Pressure Cylinders (dia x stroke) (in)20.5" x 26"20" x 26"
Tractive Effort (lbs)25,44524,219
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.64 3.92
Heating Ability
Firebox Area (sq ft)163190
Grate Area (sq ft)54.5054.50
Evaporative Heating Surface (sq ft)28012063
Superheating Surface (sq ft)490
Combined Heating Surface (sq ft)28012553
Evaporative Heating Surface/Cylinder Volume282.00218.22
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation10,90010,900
Same as above plus superheater percentage10,90012,971
Same as above but substitute firebox area for grate area32,60045,220
Power L1885919,106
Power MT422.29886.77


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