S-99291A390 5/8"-11 Locknuts

Key Features & Benefits at a Glance

• Superior vibration resistance through distorted top-lock thread design that maintains secure fastening under extreme conditions
• Enhanced durability and corrosion protection with black-oxide steel finish for extended service life in harsh environments
• Reliable thread engagement with Class 2B thread fit ensuring consistent performance and easy assembly
• High-strength performance meeting ASTM Grade C specifications for demanding industrial applications
• Standard external hex drive for convenient installation using common tools while providing excellent torque transmission
• Environmental compliance assurance with RoHS 3 and REACH standards for responsible manufacturing
• Optimized coarse threading (5/8"-11 UNC) enabling faster installation and reduced cross-threading risks

Professional Applications & Engineering Value

This heavy-duty locknut addresses critical vibration-induced loosening challenges in industrial machinery, automotive assemblies, and construction equipment. The distorted top-lock thread technology creates permanent friction along the mating surface, effectively resisting rotational forces without requiring additional locking components. Manufactured from black-oxide steel, the nut provides superior corrosion resistance while maintaining ASTM Grade C strength characteristics. The 5/8"-11 UNC coarse thread configuration ensures rapid installation in high-volume production environments while the external hex drive accommodates standard wrenching tools. This engineering solution eliminates the need for secondary locking mechanisms, reducing assembly time and maintenance requirements in vibration-prone applications while delivering consistent performance across temperature variations and dynamic loading conditions.

Specification Summary & Compliance

This locknut features Class 2B thread fit per UNC standards with precise dimensional accuracy (15/16" width, 35/64" height). Manufacturing complies with ASTM Grade C strength requirements and incorporates distorted top-lock thread technology. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental standards, containing no substances of very high concern above threshold limits. The black-oxide surface treatment provides consistent corrosion protection while maintaining dimensional stability across the 5/8"-11 coarse thread profile.