Pennsylvania Railroad FF1

The Pennsylvania Railroad FF1, nicknamed Big Liz, was a single prototype electric freight locomotive, number 3931, built in 1917 for the heavy grades over the Allegheny Mountains where the railroad planned to electrify. It had a 2-6-6-2 wheel arrangement in two half-frames, with three-phase induction motors fed by a rotary converter from single phase overhead power, and only two fixed speeds. It delivered 4,600 horsepower and 140,000 pounds-force of tractive effort, so much that it snapped couplers on trains of the day. The planned electrification never came to the mountain line, and Big Liz was scrapped in 1940.