John S Ingles (in Drury (1993)) tells us that this locomotive was procured to be compared against a single Atlantic delivered by Baldwin in the same year. After a year of trials, the Atlantic layout won and Rogers produced the batch.
RA's report conceded that the Prairies offered greater adhesive weight, as was "to be expected." "However," the report continued, " the advantage ...is somewhat offset by a larger number of driving whels and the dependent parts, with a probable increase in cost of repairs. Moreover, the first cost for this reason is greater."
Another weakness of the Prairie arrangement was its unsteadiness. RA noted the introduction of three-point suspension hangers for the trailing truck and AERJ descirbed the pair of yokes for each axle box saying that "from these yokes the load is applied to the boxes through initial stability links or 'three-point' hangers. RA commented that "It is believed that this manner of connecting the box to the equalizers will overcome much of the side motion and contribute to the steady riding of the engine."
This single Prairie was converted into a 4-6-2 in July 1907 and took the number of the experimental Atlantic.
|Specifications by Steve Llanso of Sweat House Media|
|Railroad||Illinois Central (IC)|
|Number in Class||1|
|Locomotive Length and Weight|
|Ratio of driving wheelbase to overall engine wheebase||0.44|
|Overall Wheelbase (engine & tender)||62.12'|
|Axle Loading (Maximum Weight per Axle)|
|Weight on Drivers||140200 lbs|
|Engine Weight||210800 lbs|
|Tender Light Weight||147600 lbs|
|Total Engine and Tender Weight||358400 lbs|
|Tender Water Capacity||7000 gals|
|Tender Fuel Capacity (oil/coal)||15 tons|
|Minimum weight of rail (calculated)||78 lb/yard|
|Geometry Relating to Tractive Effort|
|Boiler Pressure||200 psi|
|Cylinders (dia x stroke)||20" x 28"|
|Tractive Effort||25387 lbs|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||5.52|
|Firebox Area||201.20 sq. ft|
|Grate Area||51.08 sq. ft|
|Evaporative Heating Surface||3535 sq. ft|
|Combined Heating Surface||3535 sq. ft|
|Evaporative Heating Surface/Cylinder Volume||347.21|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||10216|
|Same as above plus superheater percentage||10216|
|Same as above but substitute firebox area for grate area||40240|