For much of the 1950s, the Pennsylvania Railroad searched for a replacement for its aging fleet of P5a electric freight engines. It even considered pulling down the catenary in favor of dieselization. But, as the railroad announced, "In May, 1958, the Pennsylvania R.R. initiated three independent studies to evaluate the economic advantages and disadvantages of diesel-electric vs. electric locomotives in the electric territory. Completed in 1959, they unequivocally proclaimed the superiority of electrification."
By that time, however, the diesel had virtually wiped out the market for new electric locomotives. General Electric was the only remaining manufacturer of electric power. For what would become its last new electric engines, the Pennsy opted for an upgrade of the 3300 horsepower E33 electrics that GE had built just a few years earlier for the Virginian Railway. The Pennsy's brick-like, six-axle E44 freighters were the same size as the earlier design but developed 4400 hp, a power rating that no single-unit diesel would rival for decades. While previous Pennsy juice jacks had been straight AC - AC power from the overhead wire was stepped down in voltage and fed to AC traction motors - the E44s were rectifier engines. Like the Virginian E33s and the New Haven EP-5 "Jets," the E44s used Ignitron Rectifiers, a new technology for converting AC to DC, enabling the new electrics to use the same DC traction motors used in diesels. While the first 60 E44s were delivered with water-cooled, somewhat delicate ignitron tubes, the final six units were equipped with more rugged and reliable air-cooled, solid-state rectifiers. Most of the earlier engines were later updated.
Delivered between 1960 and 1963, the E44s were often double- or even triple-headed in heavy freight service, and even teamed up occasionally with GG1s - motive power combinations that can easily be duplicated on any model railroad with M.T.H.'s unique Digitial Command System (DCS). In the winter of 1966, E44s could also be seen assisting on the head of GG1-powered passenger trains, when fine snow caused the GG1s some electrical problems. The E44 fleet went on to serve a succession of owners, as former Pennsy rails came under the control of the Penn Central and later Conrail. After Conrail electric service ended in 1981, a number of units worked for Amtrak until they were retired; one Amtrak unit resides today at the Railroad Museum of Pennsylvania, restored to its original Pennsy colors. New for 2007, the massive and powerful E44 joins the M.T.H. lineup, complete with fully die-cast body and authentic single-arm GE-Faively pantographs that raise and lower automatically according to the direction of travel.