The PRR J1 was a class of 2-10-4 "Texas" type steam locomotives with 69 in (180 cm) driving wheels built between 1942 and 1944. The J1 had over 95,000 pounds-force (422.6 kN) of tractive effort, plus an additional 15,000 lbf (66.7 kN) if the booster engine was used.
|Pennsylvania Railroad J1|
|Type and origin|
|Builder||PRR Altoona Works|
| • Whyte||2-10-4|
| • UIC||1′E2′ h|
|Gauge||4 ft 8 1⁄2 in (1,435 mm)|
|Driver dia.||69 in (1.753 m)|
|Length||117 ft 8 in (35.86 m)|
|Adhesive weight||377,800 lb (171.4 t)|
|Loco weight||579,975 lb (263.1 t)|
|Tender weight||377,380 lb (171.2 t)|
|Fuel capacity||60,000 lb (27.2 t)|
|Water cap||21,000 US gal (79,000 l; 17,000 imp gal)|
• Firegrate area
|122 sq ft (11.3 m2)|
|Boiler pressure||270 psi (1.86 MPa)|
|Cylinder size||29 in × 34 in (737 mm × 864 mm)|
|Maximum speed||50 mph|
|Power output||5,644 hp (4,209 kW)|
|Tractive effort||95,100 lbf (423.0 kN)|
As with many of the Pennsylvania Railroad's steam locomotives, the J1 had its headlight above the smokebox. Like the M1 the J1 had a keystone numberplate, unlike the round numberplates seen on the rest of the PRR's freight steam locomotives. Wartime restrictions forbid the design of a completely new engine so the PRR basically adopted the C&O design almost without change. As a result, they were equipped with Baker valve gear instead of Walschaerts valve gear which was more common on the PRR. Additionally, they had radial-stay fireboxes instead of the Belpaire fireboxes seen on nearly all of the Pennsylvania Railroad's steam locomotives. Mechanically, these locomotives were identical to the C&O's T-1 class 2-10-4s. As initially built, the middle driver was blind to facilitate tracking on curves. With experience the railroad determined that this wasn't necessary and after shopping the middle driver was equipped with flanges. The engine did have lateral motion devices to allow some sideways drive axle travel which did enable it to work on Pennsy curves. Other PRR changes included the curved front side cab windows, and the cast pilot with drop coupler.
During World War II the Pennsylvania Railroad needed heavier locomotives to pull freight and military equipment, but wartime restrictions prohibited the development of a new locomotive design. In response to this the Pennsylvania Railroad borrowed a 2-6-6-4 Class A of the Norfolk & Western Railway and a 2-10-4 from the Chesapeake and Ohio Railroad. Both locomotives underwent extensive testing, with the C&O 2-10-4 chosen to be produced. A total of 125 were built at PRR's shops in Juniata, Pennsylvania. They came to be known as the PRR's "War Babies," but the J1's remained in service into the 1950s. When the Pennsylvania Railroad converted from steam power to diesel, the PRR scrapped most of them in 1958 with the exception of 25. The remaining 25 were scrapped in 1959.