S-91264A640 3/8"-16 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional load-bearing capacity with 140,000 psi tensile strength and 84,000 psi shear strength for reliable performance in demanding applications.
• Permanent vibration resistance through integrated nylon pellet thread locker, maintaining secure fastening from -50° to 250°F without loosening.
• Precision alignment and reduced wear thanks to the 2-1/2" shoulder with tight diameter tolerance, ensuring accurate component positioning.
• Superior corrosion protection with black oxide finish, extending service life in harsh industrial environments.
• High-strength durability from alloy steel construction and Rockwell C32 hardness, resisting deformation under heavy loads.
• Easy installation and removal with 1/4" hex drive and knurled head for improved grip, reducing assembly time.
• Reliable thread engagement with Class 3A UNC coarse threads, providing consistent clamping force and reduced cross-threading risk.

Professional Applications & Engineering Value

This alloy steel shoulder screw is engineered to address critical alignment and vibration challenges in precision machinery. The 2-1/2" shoulder length with controlled tolerances ensures exact component spacing in assemblies like rotating shafts, bearings, and gears, minimizing misalignment and wear. The integrated nylon pellet thread locker provides permanent resistance to loosening from vibrations in automotive, aerospace, and heavy equipment applications. With black oxide finish enhancing corrosion resistance and the 1/4" hex drive facilitating quick installation, this fastener reduces maintenance downtime while maintaining structural integrity under high-stress conditions. Its UNC coarse threads and Class 3A fit deliver reliable performance in dynamic load environments where precision and durability are paramount.

Specification Summary & Compliance

This shoulder screw features Class 3A thread fit per UNC standards with precise shoulder diameter tolerance of -0.004" to -0.002" and shoulder length tolerance of -0.005" to 0.005". Manufactured to ASME B18.3 and ASTM A574 specifications, it ensures consistent quality and performance. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, making it suitable for global industrial applications requiring adherence to strict safety and sustainability standards.