Pennsylvania Railroad no. 1320

The Pennsylvania Railroad no. 1320 was a single experimental passenger three-cylinder compound 2-2-2-0 locomotive purchased by the Pennsylvania Railroad in 1889, based on the London and North Western Railway's (LNWR) Dreadnought class, designed by Francis Webb. As the railway's Crewe Works (which had built the Dreadnought classes) was not legally allowed to sell its locomotives, 1320 was instead constructed by Beyer, Peacock & Company in Manchester to the Dreadnought's specifications.

Design
The design featured a boiler pressed to 175 lbf/in2 delivering saturated steam to two outside 14 in high-pressure cylinders, which exhausted to one 30 in low-pressure cylinder inside the frames. All three cylinders had a stroke of 24 in; the high-pressure cylinders drove the rear wheels, while the low-pressure drove the leading driving wheels. As the two pairs of driving wheels were not connected, the locomotives were "duplex drive" or "double-singles".

The locomotive performed poorly for the PRR, being slow and weak compared to the line's other, domestically purchased locomotives, as well as unsuited to the rougher trackage common of U.S. railroads. The unique design of the cylinders made the locomotive difficult to operate and maintain, making it unpopular among the road's engineers and management staff. The locomotive was scrapped in 1897.