HO 4-6-6-4 Union Pacific Locomotive UP #3976 (ATHG97974)

HO-scale Union Pacific 4-6-6-4 Challenger locomotive, a detailed reproduction of UP’s WWII-era Challenger designed to move heavy freight and speed mainline runs. This edition recreates late-1940s to mid-1950s UP styling in a two-tone gray scheme with yellow lettering and striping, and it features an oil-fired boiler and a dual smokestack for authentic appearance.

Authentic detail runs throughout, from illuminated number boards and headlights to a tender back-up light, working eccentric cranks, adjustable cab vents and windows, and pivoting front and rear engines to negotiate curves as tight as 18 inches (with a minimum recommended radius of 22 inches). Current pickup on all wheels and a richly detailed boiler backhead with printed gauges add realism. Sound-equipped versions include a tender-mounted DCC decoder with SoundTraxx Tsunami2 for engine, whistle and bell sounds in both DC and DCC, with full DCC functionality and smooth slow-speed control; newer releases add dual cube speakers for fuller sound, a flickering firebox behind a see-through door, brighter LED headlights, and a sturdier loco-to-tender connection harness. CVs let modelers fine-tune performance, and a CV chart is included in the box.