PROTOTYPE SPECIFIC INFORMATION

ALCO constructed the first 4-6-6-4 locomotives in the world, numbered 3900 to 3914, for the Union Pacific Railroad in 1936. These huge engines were named the Challenger Simple Articulated, or CSA-1, class. The railroad received 25 near copies, classified as CSA-2, the following year.

Unlike compound Mallet engines that crawled along with drag freights, the Challengers had two sets of high- pressure cylinders and could safely reach passenger train speeds. The mammoth locomotives also had a heavy-duty starting tractive effort of 97,400 pounds.

Originally constructed to haul fast freight up the famous Wahsatch grade, the CSA-1 and -2 Challengers would hold a variety of assignments over their long careers- including passenger service. Depending upon their operating territory, they burned either coal or oil, and some locos were converted back-and-forth several times.

STEAM LOCOMOTIVE FEATURES:

• Illuminated number boards and headlights

• Headlight turns off in reverse

• Illuminated directional back-up light in the tender

• Correctly operating eccentric cranks

• Adjustable top cab vent and cab windows

• Pivoting front and rear engines for negotiating 18” radius curves

• Current pick-up on all driver and wheels

• Boiler backhead with full details and printed gauges

• Synchronized chuff, whistle, bell, blow-down, air compressor, dyno and pop-off valve sounds

• User-controlled whistle, short whistle, bell, squeal, coupler crash, injector, water stop and light dimmer

• Individually-applied detail parts, including brass-painted bell and whistle, piping, valves, generator, steps, air pump, air tanks, reverser and coupler lift bar

• Front coupler pocket can be inserted to mount operating coupler

• Dual cube speakers for great sound quality

• Lighted firebox flicker effect with see-through firebox door

• Upgraded headlight lighting with brighter LED

• Improved loco-to-tender connection harness for increased durability and serviceability

• Minimum recommended radius: 22”

SOUND-EQUIPPED MODELS ALSO FEATURE

• Tender-mounted DCC decoder with SoundTraxx Tsunami2 sound

• Dual cube speakers for optimal sound quality

• 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

• Precision slow speed control

• Program a multiple unit (MU) lashup with lead unit only horn, bell, and lights

• Many functions can be altered via Configuration Value (CV) changes

• CV chart included in the box

Union Pacific

ROAD NUMBER SPECIFIC FEATURES:

• #3938 Class CSA-2, Worthington feedwater heater, standard sand dome, boiler-tube pilot with wide handrails, no walkway “hump”, no steam pipe to front cylinders, unpainted metal side rods and glossy paint finish (to represent freshly-serviced and cleaned loco), special paint scheme with white walkways and wheel tires, coal burner. Athearn research photo dated AUG-1937 shows this loco with white walkways and wheel tires; we are unsure how long it lasted in this guise, but the effect is striking on this big steamer! Era Late 1937+

• #3939 Class CSA-2, Worthington feedwater heater, standard sand dome, boiler-tube pilot with wide handrails, no walkway “hump”, no steam pipe to front cylinders, unpainted metal side rods and glossy paint finish (to represent freshly-serviced and cleaned loco), oil burner. Athearn research photos dated 1937, most likely UP publicity photos, show this unit pulling the “Challenger” streamlined passenger train out of LAUPT, as well as a “photographer’s special” of twelve UP 40’ boxcars. Last CSA-2 challenger built. Era 1937+

Looking for more Athearn 4-6-6-4 Steam Locomotives? Click here!