Electrification was quickly proposed for the PRR's planned West to New York route, as steam locomotives were deemed unsuitable in the tunnels and urban areas. Initially, a system with third rail and 600 volts direct current was planned, for which two electric locomotives were developed for testing. Since they were only intended as test locomotives from the outset, they became small boxcab machines with only four axles. They were built at the PRR's Altoona Works with assistance from Westinghouse on the electrical part. The two locomotives with the B-B wheel arrangement were each given a different arrangement of the traction motors for comparison. While they were attached directly to the wheel sets in the case of number 10001, they were placed on the bogies in the case of number 10002 and driven by a gearbox. This resulted in the second machine being heavier but also running better.
The locomotives reached up to 75 mph in trial operation, but they transmitted excessively large forces to the rails. This was a big problem, especially on the 10001 with direct power transmission, and meant greater wear. So in 1916 it was sold to the Long Island Rail Road, where it was used as a switcher until 1937, nicknamed “Phoebe”. Due to the third rail, which is often interrupted in areas with many switches, and the short length of the locomotive, a compressor car had to serve as an additional pantograph. Although the 10002 remained in service with the PRR and had better running characteristics, these were still not overly good. For this very reason it was simply inferior to the “Odd D” No. 10003 with carrying axles built in 1907 and therefore no further electric locomotives without carrying axles were procured for the PRR for the time being.
