S-91259A177 5/16"-18 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance thanks to the black oxide finish, extending service life in demanding industrial environments
• Exceptional strength and durability provided by alloy steel construction with a Rockwell C32 hardness rating
• Precise and reliable fit ensured by the Class 3A thread fit, minimizing the risk of loosening under vibration
• Easy installation and removal with the hex socket drive and knurled head for improved grip during tool operation
• Robust shoulder design with a 3/8" diameter to act as a precise pivot, bearing surface, or shaft in assemblies
• Wide compatibility with the standard 5/16"-18 UNC coarse thread, suitable for common industrial applications
• Compliance with major industry standards including ASME B18.3, ensuring consistent quality and performance

Professional Applications & Engineering Value

This alloy steel shoulder screw is engineered to solve critical challenges in machinery and equipment design. The black oxide finish provides a protective layer that significantly enhances corrosion resistance, making it ideal for environments exposed to moisture or chemicals. The 5/16"-18 UNC coarse thread with a Class 3A fit offers excellent engagement and holding power, reducing the risk of thread stripping in high-stress applications. The precision-machined shoulder serves as a dependable locating dowel or axle, maintaining alignment in moving parts like gears, linkages, and pulleys. Its socket head with a knurled texture allows for secure tool engagement, facilitating quick assembly and disassembly in confined spaces, which boosts maintenance efficiency in industrial automation and heavy machinery.

Specification Summary & Compliance

This shoulder screw features a 5/16"-18 UNC thread with Class 3A fit for high precision. The shoulder diameter is 3/8" with a tight tolerance of -0.004" to -0.002", and the shoulder length is 5/16" with a tolerance of -0.005" to 0.005". It is manufactured in compliance with ASME B18.3 specifications and meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring it is free from hazardous substances.