20-2503-3 O Scale Premier SD-90MAC Diesel Engine (Non-Powered) For availability see 'Find it locally' tab $159.95Product InformationDescriptionSD-90MAC Diesel Engine (Non-Powered) - UP w/Flag Cab No. 8555 Roadname: Union PacificProduct Item Number: 20-2503-3Catalog: BJ 2004 Volume 1Product Line: PremierScale: O ScaleDelivery Status: Delivered MAR. 2004This product is compatible with all O Gauge 3-Rail track systems including those systems offered by Atlas and Gargraves and Lionel and Ross Custom Switches. OverviewAn UnPowered Unit for Realistic Double-Heading! Serious efforts to use AC (alternating current) diesel-electric engines began when General Motors introduced its 4,000-hp SD-60MAC in 1991-92. While the AC power increases an engine's adhesion, allowing it to start far heavier trains than a DC-powered locomotive of the same horsepower, the heavier load prevents AC-powered engines from reaching track speed. To solve that problem, locomotive builders have raced to design and deliver AC engines with ever-larger horsepower. In 1995 GM introduced the 5,000-hp SD-80MAC, which uses a 20-cylinder version of EMD's 710-series prime mover to generate extra power. While they were impressed with GM's results, most railroads chose to wait for the 6,000-hp SD-90MAC, but the railroads that opted to wait for the SD-90MACs initially found themselves with less power when their -90s were delivered in 1996. GM opted to deliver the engines with 4,300-hp prime movers that were designed to be replaced with 6,000-hp engines when they became available. Now that they are operating at full power with a GM16V265H engine, the SD-90MACs offer 170,000 pounds of continuous and 200,000 pounds of starting tractive effort, as well as 115,000 pounds of dynamic braking effort. Did You Know? GM claims that one SD-90MAC can replace two SD40-2's in both heavy haul and high speed freight operations. Features - Unit Measures:20 1/2" x 2 3/4" x 3 7/8" - Operates On O-42 Curves Find It LocallyThis product may not have shipped yet or is completely sold out. Click on the show button to see who might have it on order. SupportSupport Content: