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 [30], No 2 (February 1906), pp. 42-46. See also Pennsylvania Railroad No. 109-D (1908) supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange collection. (Thanks to Chris Hohl for his 12 November 2020 email correcting several items and suggesting showing the two versions in the valve gear description.) Works numbers were 31247, 37775 in September 1905.
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.)
Hohl noted as well that a later tender carried 14 tons and weighed 143,800 lb (66,227 kg) fully loaded; engine and tender wheelbase with this tender was 64 ft 10 1/4 in (19.77 m). In later diagrams, the Pennsy showed an engine weight of 240,350 lb (109,021 kg).
2761 (then renumbered 02761) was scrapped in November 1921 and 7453 went to the ferro-knacker in December 1924.
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | J28 |
| Locobase ID | 5347 |
| Railroad | Pennsylvania (PRR) |
| Country | USA |
| Whyte | 2-6-2 |
| Number in Class | 2 |
| Road Numbers | 2761, 7453 |
| Gauge | Std |
| Number Built | 2 |
| Builder | Alco-Schenectady |
| Year | 1905 |
| Valve Gear | Stephenson or Walschaert |
| 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 wheelbase | 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 / Liters/MT) | 10 / 9 |
| 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 / 1380 |
| 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 | |
| Tubes (number - dia) (in / mm) | 322 - 2.25" / 57 |
| Flues (number - dia) (in / mm) | |
| Flue/Tube length (ft / m) | 19.42 / 5.92 |
| Firebox Area (sq ft / m2) | 198 / 18.39 |
| Grate Area (sq ft / m2) | 55 / 5.11 |
| Evaporative Heating Surface (sq ft / m2) | 3881 / 360.55 |
| Superheating Surface (sq ft / m2) | |
| Combined Heating Surface (sq ft / m2) | 3881 / 360.55 |
| Evaporative Heating Surface/Cylinder Volume | 329.74 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 11,000 |
| Same as above plus superheater percentage | 11,000 |
| Same as above but substitute firebox area for grate area | 39,600 |
| Power L1 | 11,036 |
| Power MT | 437.38 |