From the dawn of dieselization through its first six decades, virtually every American diesel locomotive used DC traction motors. By the early 1990s, however, a series of technological advances allowed designers to tap the inherent superiority of AC traction - namely, the ability of an AC motor to start a heavier load than a DC motor, with the same prime mover. The superior adhesion of AC power touched off a new horsepower race because, with the same number of wheels, AC traction could put more horsepower on the rails.
Two years behind rival EMD, General Electric entered the AC traction business in June 1993 with the AC4400CW - 4400 horsepower, "C" for 3-axle trucks, and "W" for wide North American cab. The new engine was basically an AC version of the Dash 9-44CW introduced the same year. The key external difference between the two engines is the large box behind the cab on the left side of the AC 4400CW, which houses much of the AC traction electronics.
Although General Electric's AC power arrived on the scene later, its AC engines have outsold those made by EMD. One reason may be GE's use of one inverter bank per traction motor, a design that allows the crew to cut out a single malfunctioning motor and still retain more than 80% of a locomotive's function. On a comparable EMD AC-powered engine, an entire truck has to be taken offline if one of its three motors fails.
One area of weakness for GE was its high adhesion trucks, which were generally acknowledged to be inferior to EMD's steerable radial truck. Later model AC4400CWs feature GE's own version of a steerable truck, which improves adhesion on curves.
Now you can bring the brute strength of the AC4400CW to your own freight operations. New to the M.T.H. lineup, this model offers the industry-leading features you expect in a Premier diesel: awesome sounds, superb detailing, see-through body grilles, a wealth of added-on details, and smooth operation at any throttle setting from a crawl to high-speed mainline service.