Between 1936 and 1944, the American Locomotive Company (ALCO) constructed a total of 105 Challengers in five classes for the Union Pacific. These locomotives were approximately 122 ft (37 m) long and weighed 537 short tons (487 tonnes). While primarily used for freight service across the Union Pacific system, a few were also assigned to passenger trains like the Portland Rose. The design and operational experience of the Challengers played a crucial role in shaping the renowned Big Boy locomotive type, which, in turn, influenced the design of the last three orders of Challengers.
The Challengers boasted several technical breakthroughs that contributed to their success. Operating with a high boiler pressure of 280 lbf/in2, a feature typically reserved for passenger locomotives such as the FEF Series, they sported 69-inch drivers—impressive mammoth wheels typically found on passenger locomotives. Most freight engines required smaller wheels to generate the necessary torque. Surpassing speeds of 60 miles per hour, which was unprecedented for most other railroads using articulated steam locomotives, became a regular occurrence on the Union Pacific.
Locomotive Features:
- N Scale
- Ready to Run
- DCC equipped
- Sound equipped
- Paragon4 Sound & Control system featuring Rolling Thunder
- Dual-mode decoder with back EMF for superb slow speed operation in DC and DCC modes
- Precision drive mechanism engineered for heavy towing and smooth slow speed operation
- Operating smoke unit with on/off switch
- Smoke unit requires thin-viscosity smoke fluid such as JT's Mega-Steam (sold separately)
- Six drivers and all tender wheels pick-up electricity from track
- Die-cast locomotive body
- Die-cast chassis for heavier weight and maximum tractive effort
- Premium caliber painting
- Prototypically accurate paint scheme
- Separately applied details including handrails, grab irons, piping, tender ladders, whistle and bell
- Prototypical headlight and rear light operation
- Separately controllable cab light
- Prototypically accurate UP Challenger sounds
- Operating Micro-Trains compatible knuckle couplers
- Will operate on standard Code 80 track as well as Code 55 and Code 70
- Minimum required operating radius: 9.75 inches
Paragon4 Sound & Control System Features:
- Operates in DC and DCC modes with improved DC speed control
- DCMaster is needed for DC Sound (sold separately)
- Built-in extra capacitance to navigate imperfect track
- Pro lighting mode offers individual control of all lights on the model
- Switcher mode for precise low speed control
- Record & Play operation - records and plays back sounds and movements once or repeatedly for automatic operation
- High resolution audio
- Quillable horn for various whistle lengths and patterns
- Choice of 3 selectable horns
- Adjustable bell ringing interval for faster or slower bell
- Numerous user-mappable functions with available keys
- Multiple realistic passenger and crew sounds play on command
- Grade crossing automatic signal
- Individually adjustable sound volumes for each effect
- EZ reset button for quick return to factory default settings
