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 Wheelbase7'7'
Engine Wheelbase28.71'28.25'
Ratio of driving wheelbase to overall engine wheebase 0.24 0.25
Overall Wheelbase (engine & tender)56.46'59.25'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers92500 lbs95000 lbs
Engine Weight167300 lbs177100 lbs
Tender Light Weight162000 lbs152000 lbs
Total Engine and Tender Weight329300 lbs329100 lbs
Tender Water Capacity7400 gals7400 gals
Tender Fuel Capacity (oil/coal)18 tons13 tons
Minimum weight of rail (calculated)77 lb/yard79 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter73"73"
Boiler Pressure200 psi200 psi
Cylinders (dia x stroke)20.5" x 26"20" x 26"
Tractive Effort25445 lbs24219 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.64 3.92
Heating Ability
Firebox Area163 sq. ft190 sq. ft
Grate Area54.50 sq. ft54.50 sq. ft
Evaporative Heating Surface2801 sq. ft2063 sq. ft
Superheating Surface490 sq. ft
Combined Heating Surface2801 sq. ft2553 sq. ft
Evaporative Heating Surface/Cylinder Volume282.00218.22
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation1090010900
Same as above plus superheater percentage1090012971
Same as above but substitute firebox area for grate area3260045220
Power L1885919106
Power MT422.29886.77


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