PRR L1s

PRR L1s
Preserved #520 at the Railroad Museum of Pennsylvania.
Type and origin Power type Steam Designer J. T. Wallace, Alfred W. Gibbs, Axel Vogt Builder PRR Juniata Shops (344), Baldwin Locomotive Works (205), Lima Locomotive Works (25) Build date 1914–1919 Total produced 574
Specifications Configuration: ​  • Whyte 2-8-2  • UIC 1'D1' Leading dia. 33 in (0.84 m) Driver dia. 62 in (1.57 m) Trailing dia. 50 in (1.27 m) Wheelbase 36 ft 4.5 in (11.087 m) (locomotive) Length 82 ft 0.25 in (25.0000 m) (including 90F75 tender) Height 15 ft 0 in (4.57 m) Boiler pressure 205 psi (1.41 MPa) Cylinders 2 Cylinder size 27 in × 30 in (690 mm × 760 mm)
Performance figures Tractive effort 61,465 lbf (273.41 kN) Factor of adh. 3.78
Career Preserved 1

Class L1s on the Pennsylvania Railroad comprised 574 2-8-2 "Mikado" type steam locomotives constructed between 1914 and 1919 by the railroad's own Juniata Shops (344 examples) as well as the Baldwin Locomotive Works (205) and the Lima Locomotive Works (25). It was the largest class of 2-8-2 locomotives anywhere, although other railroads had more Mikados in total.

The L1s shared the boiler and many other components with the K4s 4-6-2 "Pacific" type, giving a total of 999 locomotives with many standard parts.

Although the L1s type was quite successful, it was very much eclipsed in PRR service by the larger and more powerful I1s/I1sa 2-10-0 "Decapods", which arrived in service only two years after the L1s and were very suited to the PRR's mountain grades and heavy coal and mineral trains, and by the 1923 introduction of the M1 4-8-2 "Mountains" which took on the best high-speed freight runs. Large numbers of the class were stored out of service during the Great Depression, only to return to service during World War II.

The L1s design was state-of-the-art for its time and comparable with the best being produced for any other road. In fact, the specifications of the L1s and the Santa Fe's similar 3160 class locomotives were the basis for the USRA's successful Heavy Mikado standard design, which was built to the total of 957 locomotives.

As built, however, the class was lacking much in the way of modern appliances due to the PRR's conservatism; features missing included a mechanical stoker, power reverse, and a feedwater heater, although most of the class were later given a stoker and all received power reverse.