Atlas HO 10005037  - Master - Gold - S-4 Diesel Locomotive "U.S. Steel" #77 

• Road Name: U.S. Steel 
• Road Number: 77 
• Product Line: Master - Gold
• Scale: HO Scale
• Catalog: Atlas Winter 2025 Catalog

Features:

• 5-pole skewed armature motor for reliable operation
• Dual-flywheels for maximum performance at all speeds
• Exceptional painting and printing
• Sturdy die-cast mainframe and gear cases
• Metal couplers
• Gold models are equipped with ESU LokSound

ESU Loksound Functionality Features:
• ESU LokSound decoder, supporting all DCC programming modes.
• Flexible mapping of function keys F0 to F31.
• Follows all NMRA DCC standards and recommended practices.
• Over 20 sound effects are available, including engine start-up and shutdown, prime mover sounds through all eight notches,
bell, air horn, air compressor, and more

Overview:

Alco introduced the S-4 locomotive in 1950. The S-4, like the earlier S-2, was a 1000-horsepower switcher. Nearly 800 units were built for North American (Alco) and Canadian (by Alco’s Canadian subsidiary Montreal Locomotive Works) railroads between 1947 and 1956. The primary spotting difference between the S-2 and the S-4 can be noted in the trucks. The S-2 has Blunt trucks, while the S-4 has AAR-style trucks. The versatility of the S-2s and S-4’s was evidenced by their service in mainline railroads, shortlines, and industrial switching operations. The S-4, along with the S-2, became one of ALCO’s most successful diesel switchers, helping railroads transition from steam to diesel. Its rugged design and turbocharged engine made it a favorite for heavy switching duties. Canadian railroads were significant buyers, thanks to MLW production. Many units remained in service for decades, and several are preserved or still operating on short lines and tourist railroads today.