MTH ELECTRIC TRAINS

The first experiments with AC (alternating current) rather than DC (direct current) diesel-electric engines began in the 1960s. They did not get going in earnest, however, until General Motors plunged into the field with its 4,000-hp SD60MAC in 1991-92, discovering that the AC motors increased an engine's adhesion and allowed it to start a far heavier train than a DC locomotive of the same horsepower. They discovered, however, that horsepower did matter when the engines tried to run at speed; the heavier load slowed the engines down and prevented them from reaching track speed. Things have moved quickly since these discoveries. By 1996 GM had delivered the SD-90MAC, an engine that was delivered with a 4,300-hp prime mover that was designed to be replaced by a 6,000 version as soon as it became available. Now that they are operating at full power with a GM16V265H engine, GM claims that one SD-90MAC can replace two SD40-2's in both heavy haul and high speed freight operations. M.T.H. is proud to present a replica of this massive engine in the markings of the Canadian Pacific, Norfolk Southern, and Union Pacific railroads. With Loco-Sound or Proto-Sound 2.0, which offers the most realistic operation in model railroading, your SD-90MAC will be the king of your layout. Pull-out fact: The SD-90MAC generates an astonishing 170,000 pounds of continuous and 200,000 pounds of starting tractive effort as well as 115,000 pounds of dynamic braking effort.