Pennsylvania 2-6-2 "Prairie" Locomotives of the USA

Class Details by Steve Llanso of Sweat House Media

Class J28 (Locobase 5347)

Data from "Locomotive for Experiment, Pennsylvania Railroad," Railway Master Mechanic, Vol XXX, # 2 (February 1906), pp. 42-46.

According to Bob Berkey of (visited 8 February 2003), Alco built two locomotives, #2761 (outside piston valves and Walschaert's gear) and #7453 (inboard piston valves and Stephenson valve gear). 7453 had slightly different heating surface areas.

Clearly experimental (being built by Alco practically guaranteed non-acceptance on the Pennsy) as a halfway measure between the 4-4-2s they already built in quantity and the 4-6-2 being adopted by many other roads. (A 1912 photo of 7453 in Fort Wayne -- -- shows a wagon-top boiler also uncharacteristic of Pennsy engines.

Berkey notes that one was still on the roster in 1924, but both were gone by the end of 1929.

Specifications by Steve Llanso of Sweat House Media
Locobase ID5347
RailroadPennsylvania (PRR)
Number in Class2
Road Numbers2761, 7453
Number Built2
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase14'
Engine Wheelbase34.25'
Ratio of driving wheelbase to overall engine wheebase 0.41
Overall Wheelbase (engine & tender)64.52'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers166880 lbs
Engine Weight234500 lbs
Tender Light Weight139300 lbs
Total Engine and Tender Weight373800 lbs
Tender Water Capacity7000 gals
Tender Fuel Capacity (oil/coal)10 tons
Minimum weight of rail (calculated)93 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter80"
Boiler Pressure200 psi
Cylinders (dia x stroke)21.5" x 28"
Tractive Effort27504 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 6.07
Heating Ability
Firebox Area202.70 sq. ft
Grate Area55 sq. ft
Evaporative Heating Surface3882 sq. ft
Superheating Surface
Combined Heating Surface3882 sq. ft
Evaporative Heating Surface/Cylinder Volume329.95
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation11000
Same as above plus superheater percentage11000
Same as above but substitute firebox area for grate area40540
Power L111096
Power MT439.76


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