S-99291A120 5/16"-18 Locknuts

Key Features & Benefits at a Glance

• Superior vibration resistance through distorted top-lock threads that maintain secure fastening under dynamic loads
• Enhanced corrosion protection with zinc yellow-chromate plating for extended service life in harsh industrial environments
• Reliable mechanical performance backed by ASTM Grade C certification for consistent strength and durability
• Easy installation and removal with standard external hex drive design compatible with common wrench tools
• Precise thread engagement with Class 2B thread fit ensuring smooth assembly and reduced cross-threading risks
• Optimized for coarse thread applications using 5/16"-18 UNC threads for quick installation in various materials
• Right-hand threading compatibility with standard industrial equipment and existing fastener systems

Professional Applications & Engineering Value

This 5/16"-18 UNC locknut delivers critical vibration resistance where conventional fasteners fail. The distorted thread locking mechanism creates permanent friction along the mating surface, preventing loosening from machinery vibration, impact loads, and thermal cycling. Manufactured from zinc yellow-chromate-plated steel, it provides superior corrosion protection for outdoor equipment, automotive assemblies, and industrial machinery exposed to moisture and chemicals. The ASTM Grade C material specification ensures consistent performance in high-stress applications, while the external hex drive allows for precise torque application during installation. Engineers specify this solution for conveyor systems, motor mounts, and structural frameworks where vibration-proof fastening is non-negotiable for operational safety and reduced maintenance intervals.

Specification Summary & Compliance

This locknut features 5/16"-18 UNC coarse threads with Class 2B thread fit for standard tolerance applications. Dimensions include 1/2" width across flats and 17/64" height. Manufactured to ASTM Grade C specifications for mechanical properties and performance standards. The distorted top-lock thread design complies with industrial locking fastener requirements, while the zinc yellow-chromate plating meets corrosion protection standards for industrial components.