GE AC44C6M

The AC44C6M emerged from a cooperative effort between GE Transportation and several North American railroads seeking a cost-effective alternative to purchasing new AC-traction locomotives outright. The rebuild program began in earnest in September 2015, with Norfolk Southern becoming the defining customer of the type after receiving its first rebuilt units toward the end of that year. The economic rationale was compelling: converting existing Dash 9 cores into modern AC-traction locomotives cost only roughly half to three-fifths the price of acquiring brand-new equipment, while Wabtec reported substantial gains in fuel efficiency, reliability, and tractive capability compared to the original DC-traction predecessors. Norfolk Southern grew into the largest single operator of the AC44C6M, with more than 600 units rebuilt as of 2022 and plans for several hundred additional conversions extending through 2025. The railroad drew its rebuild candidates from its sizable fleet of Dash 9-40C and Dash 9-40CW locomotives, with ambitions to eventually convert all remaining Dash 9-40CW units to the AC44C6M standard. Other operators have included Canadian National, which placed an initial order for 50 units delivered starting in October 2022 and subsequently expanded its commitment to more than 120 locomotives, and the Quebec North Shore and Labrador Railway, which acquired 19 examples rebuilt from former BNSF Dash 9 units. Fortescue, the Australian iron ore mining company, operates approximately 28 AC44C6Ms featuring enlarged radiators suited to the demanding thermal environment of Western Australia. Union Pacific and CSX have also announced or pursued rebuild programs involving Dash 9 fleets, though Union Pacific classifies its rebuilt units under its own C44ACM designation. The AC44C6M program represents a broader industry trend toward life-extension rebuilding rather than wholesale fleet replacement, allowing railroads to modernize traction technology and onboard systems while avoiding the full capital expenditure of new construction. The rebuilds are performed not only by GE and its successor Wabtec but also by American Motive Power and, notably, by Norfolk Southern's own Juniata and Roanoke shops, making it one of the few modern locomotive types built in significant numbers by railroad-owned facilities.

The AC44C6M is built on the underframe of either a C40-8W or a C44-9W donor locomotive, retaining the original engine compartment, radiator section, and the 16-cylinder 7FDL prime mover from the core unit. The most significant mechanical change is the replacement of the original DC traction motors with GE 5GEB13B7 AC traction motors, six in total arranged in a C-C wheel configuration, along with new inverter equipment housed in a dedicated cabinet added immediately behind the cab. This conversion to AC traction is central to the reported 55 percent improvement in haulage capability, as AC motors offer substantially higher continuous tractive effort than their DC counterparts, particularly at low speeds. The rebuilt locomotives are rated at 4,400 horsepower, consistent with the higher-powered Dash 9 variants from which most examples are sourced. Externally, the rebuilds are distinguished by a new front hood section accommodating the inverter cabinet, and Norfolk Southern's units rebuilt from narrow-cab Dash 9-40C locomotives received entirely new wide-nose cabs in the process, significantly updating their appearance and crew accommodations. Norfolk Southern's AC44C6Ms also incorporated a range of modern operational systems including cab signals, distributed power unit capability, Positive Train Control, locomotive speed limiting equipment, an underfloor air conditioning system, and on select units, electronically controlled pneumatic braking. Fortescue's fleet is an example of how the platform has been adapted for specific operational requirements, with those units featuring a larger radiator package to cope with the extreme ambient temperatures encountered in Australian heavy-haul service.

Models by: ScaleTrains