Pennsylvania 2-6-2 "Prairie" Locomotives in 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.

Principal Dimensions 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 Wheelbase (ft / m)14 / 4.27
Engine Wheelbase (ft / m)34.25 / 10.44
Ratio of driving wheelbase to overall engine wheebase 0.41
Overall Wheelbase (engine & tender) (ft / m)64.52 / 19.67
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)166,880 / 75,696
Engine Weight (lbs / kg)234,500 / 106,368
Tender Loaded Weight (lbs / kg)139,300 / 63,185
Total Engine and Tender Weight (lbs / kg)373,800 / 169,553
Tender Water Capacity (gals / ML)7000 / 26.52
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)10 / 9.10
Minimum weight of rail (calculated) (lb/yd / kg/m)93 / 46.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)80 / 2032
Boiler Pressure (psi / kPa)200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)21.5" x 28" / 546x711
Tractive Effort (lbs / kg)27,504 / 12475.62
Factor of Adhesion (Weight on Drivers/Tractive Effort) 6.07
Heating Ability
Firebox Area (sq ft / m2)202.70 / 18.84
Grate Area (sq ft / m2)55 / 5.11
Evaporative Heating Surface (sq ft / m2)3882 / 360.78
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)3882 / 360.78
Evaporative Heating Surface/Cylinder Volume329.95
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation11,000
Same as above plus superheater percentage11,000
Same as above but substitute firebox area for grate area40,540
Power L111,096
Power MT439.76

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Wes Barris