Union Pacific
In the spring of 1941 UP locomotive designers began working on a locomotive to team up with the new 4-8-8-4 Big Boy's then under construction at Alco. The Big Boy's were designed to pull heavy freights up the Wasatch Range in Utah to the division point at Green River, WY. What was needed was a locomotive to take over at that point that could speed the freights eastward across the Wyoming Division. Building on their experience with the original CSA 4-6-6-4 Challengers UP and Alco's designers developed a newer and better Challenger type locomotive. The result was a group of 65 4-6-6-4 Challenger built in three separate groups during World War II. 

ROAD NUMBER SPECIFIC FEATURES: 
#3985
Modern Excursion version
Oil Burner
Era 1980's - 2000's

#3933
Coal Burner
Dual smoke stack
Tender bunker coal extensions
Era 1940's - 1959

#3967
Coal Burner
Dual smoke stack
Smoke Lifters
Era 1940's - 1959

#3997
Coal Burner
Dual smoke stack
Tender bunker coal extensions
Era 1940's - 1959

Union Pacific
UP painted several of their Challengers in their two-tone grey paint scheme for passenger service. They also added smoke lifters and converted many to oil burners as well.   

ROAD NUMBER SPECIFIC FEATURES: 
#3976
Two-tone grey w/ yellow lettering and striping. Oil burner
Dual smoke stack. Era: Late 1940's - Mid-1950's.

STEAM LOCOMOTIVE FEATURES: 
DCC-ready features Quick Plug™ plug-and-play technology
Scaled from prototype resources including drawings, field measurements, photographs, and more
Accurately-painted and –printed paint schemes
Full cab interior with boiler backhead with printed gauges
Individually applied piping, valves, generators, etc.
Operating eccentric cranks on both sides operating in correct direction
Headlights and indicator number boxes (number boards) with directional light change
Five pole, skewed armature motor with flywheel for smooth operation
Pivoting front and rear engines for negotiating 11" radius curves
See-through running boards
See-through cab windows
McHenry® scale knuckle couplers
LED Lighting for realistic appearance
Fully-assembled and ready-to-run
Heavy die-cast frame for greater traction and more pulling power
Packaging securely holds for the model for safe storage
Minimum recommended radius: 15"

SOUND EQUIPPED MODELS ALSO FEATURE
Tender-mounted DCC decoder with SoundTraxx Tsunami2 sound
Sound, units operate in both DC and DCC
Full DCC functions available when operated in DCC mode
Engine, whistle, and bell sounds work in DC
All functions NMRA compatible in DCC mode
Excellent Slow speed control
Many functions can be altered via Configuration Value (CV) changes
CV chart included in the box

PROTOTYPE SPECIFIC INFORMATION
The name "Challenger" was given to steam locomotives with a 4-6-6-4 wheel arrangement. This means that they have four wheels in the leading pilot truck, which helps guide the locomotive into curves, two sets of six driving wheels, and finally four trailing wheels, which support the rear of the engine and its massive firebox. Each set of six driving wheels is driven by two steam cylinders. In essence, the result is two engines under one boiler. The Union Pacific Railroad sponsored development of this type to meet the need for higher speeds in main-line service. Historically, articulated locomotives had been limited to slow speeds by factors inherent in their design. The technical breakthroughs achieved with the Big Boy enabled the carrier to develop a newer, improved Challenger that met their speed expectations. 

Though originally intended for freight service, many Challengers were used in passenger service.  

Product Specs
Manufacturer #
797534255425
Sub Brand
ATHEARN
Lighted
LED
Sound
Ready
Reporting Mark
UP
Era
1911-1940, 1941-1970
Prototype Manufacturer
American Locomotive Company (ALCO)
Scale
N
Wheel Configuration
4-6-6-4
DCC
Ready/21-Pin NEM