Pre-Order | Next Shipment September 2024
Athearn - Item No. ATHG41179
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HO U50 Locomotive with DCC & Sound, SP #9951

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  • SP Style “Big Hole” Emergency light (Flash function in DCC only)
  • Classification lights (Function in DCC only)
  • Working Truck lights
  • Number board lights
  • MU hoses
  • Separate see-through air intake grills

Due to the increase of better highways in the 1950’s the trucking industry was beginning to siphon off time sensitive traffic from the railroads. Consequently, in the late 1950’s the Southern Pacific and the Union Pacific railroads were seeking ways to increase the horsepower of their locomotives to help improve train speeds without having to add more locomotives to their trains. The SP was striving to improve transit times on their Sunset Route freights and was utilizing large groups of lower horsepower locomotives to do so. One method to achieve these goals was to mount two complete prime movers on one chassis. UP asked the 3 major locomotive builders at that time to submit proposals using this concept. In response, General Electric created their 5,000-horsepower U50 model, a design which utilized two 2500-horsepower prime movers. SP decided to give 3 of them a try, receiving them in the summer of 1964, but chose not to order any others. They spent most their early service lives working on SP’s Sunset Route and ended their SP careers in the 1970’s working in drag freight service in the Los Angeles Basin in California. All three were scrapped by 1979.


  • Illuminated truck lights
  • Illuminated classification lights
  • Illuminated number boards
  • See-through air intakes
  • 4-cube speakers
  • Minimum radius: 18” — Recommended radius: 22”

  • Coupler cut levers
  • MU hoses
  • Trainline hose
  • See-through cab windows
  • Full cab interior
  • Walkway tread
  • Windshield wipers
  • Wire grab irons
  • DCC-ready features Quick Plug™ plug-and-play technology with 21-pin NEM connector
  • Fine-scale Celcon handrails for scale appearance
  • Detailed fuel tank with fuel fillers, fuel gauges, breather pipes, and retention tanks
  • Body-mounted McHenry® operating scale knuckle couplers
  • Genesis driveline with 5-pole skew wound motor, precision machined flywheels, and multi-link drivetrain for trouble free operation
  • All-wheel drive with precision gears for smooth and quiet operation
  • All-wheel electrical pickup provides reliable current flow
  • Wheels with RP25 contours operate on all popular brands of track
  • LED Lighting for trouble free operation
  • Heavy die-cast frame for greater traction and more pulling power
  • Scaled from prototype resources including drawings, field measurements, photographs, and more
  • Accurately-painted and –printed paint schemes
  • Fully-assembled and ready-to-run
  • Packaging securely holds the model for safe storage


  • Onboard DCC decoder with SoundTraxx Tsunami2 sound
  • Four cube speakers for optimal sound quality
  • Sound units operate in both DC and DCC
  • Full DCC functions available when operated in DCC mode
  • Engine, horn, and bell sounds work in DC
  • All functions NMRA compatible in DCC mode
  • Precision slow speed control
  • Program a multiple unit (MU) lash up with lead unit only horn, bell, and lights
  • Many functions can be altered via Configuration Value (CV) changes
  • CV chart included in the box


In 1963, the diesel horsepower race had just reached 2,500 horsepower and the only way to get 5,000 horsepower was by putting two diesel engine and generator sets onto one chassis. Given the wheel slip and traction motor technology at the time, eight traction motors and powered axles were needed to convert the horsepower into pulling power. EMD had already produced the DD35, two cab less GP35s on one chassis. General Electric’s answer was to do the same with two U25Bs, which created the U50.

The U50 was 83 feet 6 inches long and towered over most contemporary locomotives at 15 feet 10 inches tall. They weighed in at 559,620 pounds and produced 139,175 pounds of starting tractive effort. Inside the hood were two FDL-16 diesel engines, each with a generator, full radiator, and dynamic brake setup. The U50 rode on two sets of two-axle AAR-B trucks mounted on a span bolster. The trucks were recycled from the scrapped gas turbines. Up front was a tall, blunt nose cab without a front walkway, which gave the U50 its unique appearance.

Product Specs

1941-1970, 1971-1990
Prototype Manufacturer
Reporting Mark
Sub Brand