The Union Pacific Challengers were a class of powerful, simple articulated 4-6-6-4 steam locomotives built by the American Locomotive Company (ALCO) exclusively for the Union Pacific Railroad. Between 1936 and 1943, a total of 105 were constructed. Measuring an impressive 122 feet (37 m) in length and weighing 628,000 pounds (284,800 kg), these locomotives were primarily assigned to freight service across the vast Union Pacific system. However, a select few also hauled passenger trains through the rugged mountain territories of California and Oregon.
Designed specifically for Union Pacific’s demanding operating conditions, the Challengers represented a significant step forward in high-speed articulated locomotive technology. Much of the engineering experience gained from the Challenger program directly influenced the creation of the railroad’s legendary Big Boy locomotives.
The name “Challenger” refers to the 4-6-6-4 wheel arrangement: four leading wheels in the pilot truck to guide the locomotive through curves, two sets of six driving wheels powered by a total of four steam cylinders, and four trailing wheels supporting the massive firebox. In essence, each Challenger was two engines operating under one boiler. Prior to their introduction, articulated steam locomotives were generally limited to slower speeds due to design constraints. Union Pacific’s technical innovations broke that barrier, making sustained speeds over 60 mph—unheard of for articulated locomotives on other railroads—routine on their main lines.
In this production run, we are offering multiple era-specific versions: As-Delivered Front Engine, Rebuilt Front Engine, and Integral Cast Cylinder Front Engine. Alongside these historically accurate models, we are also producing three striking fantasy schemes and an unlettered, painted brass version for maximum customization.
All models are available in two configurations: Paragon4 Sound/DC/DCC with Smoke or our Stealth Series—No-Sound, DCC-Ready models with factory-installed speakers. The Stealth Series allows customers to easily install their own 21-pin DCC decoder for a simple “plug-and-play” upgrade.
Industry-leading Model Features:
•ALL-NEW Paragon4 Sound & Control System
• Synchronized Puffing Smoke with Chuff Sound
• Variable Puffing Smoke Intensity and timing
• Integral DCC Decoder with Back EMF for Industry-Best Slow Speed Operation in DC and DCC
• Precision Drive Mechanism engineered for continuous heavy load towing and smooth slow speed operation
• 5-Pole Can Motor with Skew Wound Armature
• Hand crafted Brass Boiler, Tender Body, and diecast Chassis for maximum Tractive Effort
• Prototypically Accurate Details for Each Road Number
• Many Separately Applied Details such as Handrails, Ladders, Piping, Cab Glass, Whistle, Brass Bell, Markers, Numberboards, Air Tanks, and Many Others
• Premium Caliber Painting with Authentic Paint Schemes
• Prototypical Light Operation with Separately Controllable Headlight, Reverse Light, Cab Light, Front Numberboards, Rear Marker Light
• Factory-installed Engineer and Fireman Figures
• Two operating Kadee-compatible couplers.
• Equipped with Rubber Traction Tires for Increased Pulling Power
• Will Operate on Code 70, Code 83, and Code 100 Rail
• Recommended Minimum Radius: 22 inches
• Accurate Prototypical Sounds for the Union Pacific Early Challenger
Broadway Limited Imports is proud to introduce Paragon4: The new benchmark for premium HO sound-equipped locomotives. These DC and DCC-Sound equipped locomotives feature the ALL-NEW Paragon4 sound and control system. Each Paragon4 locomotive comes with BLI's own integral DCC Decoder factory installed. Paragon4 locomotives offer Dual Mode DC and DCC operation with superb back EMF motor control, improved DC motor control, built-in capacitor pack for more reliable electrical pick-up, industry best on-board sound with Rolling Thunder functionality, Pro Lighting Mode for prototypical light control, Switcher model for precise low speed control, recordable DCC operation for automated playback, and the same excellent detail level as Broadway Limited's Paragon3 Series models.
Paragon4 Sound & Control System Features:
• Operates in DC & DCC with improved DC speed control (use DCMaster for DC Sound)
• Built-In capacitor pack to navigate imperfect track
• Capacitor Pack automatically disabled on program track for full compatibility with JMRI Decoder Pro
• Pro Lighting Mode offers individual control of all lights on 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 Whistle for various whistle lengths and patterns
• Choice of 3 selectable whistles
• Alternate Whistle / Horn where applicable for locomotive with air horn and steam whistle - both the main whistle and alternate can be easily played
• Adjustable bell ringing interval for faster or slower bell
• Numerous user-mappable functions with available keys
• Johnson Bar Sound at Direction Change
• Multiple realistic passenger and crew sounds play on command
• Grade Crossing Automatic Signal
• Automatic Forward / Reverse Signal - When activated, stopping triggers and stop whistle toot. When moving forward from a stopped position, toots twice. When moving in reverse. toots three times.
• Chuff sound intensity varies with load
• Individually adjustable sound volumes for each effect
• EZ Reset Button for quick return to factory default settings
**Specifications on this page subject to change.
