Interstate 2-8-8-2 "Chesapeake" Locomotives of the USA

Class Details by Steve Llanso of Sweat House Media

Class 20 (Locobase 6441)

Data based on (visited 26 Dec 2004). The diagram indicates that these were based on the USRA heavy articulated, but were intended to negotiate 22-deg curves. As a result, each set of drivers had a 3" longer wheelbase and the engine wheelbase measured a total of 3" longer.

The diagram is less informative about heating surfaces, giving only the total of evaporative and superheater combined as 8,332 sq ft. This is 737 sq ft more than the USRA standard.

Specifications by Steve Llanso of Sweat House Media
Locobase ID6441
RailroadInterstate (IRR)
Number in Class2
Road Numbers20-21
Number Built2
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft)15.75
Engine Wheelbase (ft)58
Ratio of driving wheelbase to overall engine wheebase 0.27
Overall Wheelbase (engine & tender) (ft)94.25
Axle Loading (Maximum Weight per Axle) (lbs)62,000
Weight on Drivers (lbs)486,500
Engine Weight (lbs)541,000
Tender Loaded Weight (lbs)209,200
Total Engine and Tender Weight (lbs)750,200
Tender Water Capacity (gals)12,000
Tender Fuel Capacity (oil/coal) (gals/tons)16
Minimum weight of rail (calculated) (lb/yd)101
Geometry Relating to Tractive Effort
Driver Diameter (in)57
Boiler Pressure (psi)240
High Pressure Cylinders (dia x stroke) (in)25" x 32"
Low Pressure Cylinders (dia x stroke) (in)39" x 32"
Tractive Effort (lbs)101,465
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.79
Heating Ability
Firebox Area (sq ft)
Grate Area (sq ft)96.50
Evaporative Heating Surface (sq ft)
Superheating Surface (sq ft)
Combined Heating Surface (sq ft)
Evaporative Heating Surface/Cylinder Volume
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation23,160
Same as above plus superheater percentage23,160
Same as above but substitute firebox area for grate area
Power L1
Power MT

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