S-99291A190 7/8"-9 Locknuts

Key Features & Benefits at a Glance

• Superior vibration resistance through distorted thread technology, ensuring reliable performance in high-stress environments
• Enhanced corrosion protection with zinc yellow-chromate plating, extending service life in harsh industrial conditions
• High-strength durability meeting ASTM Grade C standards, providing dependable load-bearing capacity for heavy-duty applications
• Easy installation and removal with a standard external hex drive design, reducing assembly time and labor costs
• Secure locking mechanism via top lock distorted threads, preventing loosening under dynamic loads and vibrations
• Precise thread fit with Class 2B tolerance and coarse UNC threading, ensuring compatibility and reducing cross-threading risks
• Robust dimensions (1 5/16" width, 3/4" height) for stable gripping and consistent torque application in demanding setups

Professional Applications & Engineering Value

This 7/8"-9 UNC locknut is engineered to address critical challenges in industrial fastening, where vibration-induced loosening can compromise safety and operational integrity. The distorted thread locking type creates intentional interference, maintaining clamp force without requiring additional components like washers or adhesives. Made from zinc yellow-chromate-plated steel, it resists oxidation and chemical exposure in sectors such as machinery assembly, construction, and transportation. The coarse thread and Class 2B thread fit facilitate quick alignment and reduce installation errors, while the external hex drive style allows for high-torque application using standard tools. Ideal for permanent fastening in heavy equipment, structural frameworks, and automotive systems, this nut delivers long-term reliability under cyclic loading and harsh environmental conditions.

Specification Summary & Compliance

This locknut adheres to UNC coarse thread standards with a 7/8"-9 thread size and Class 2B thread fit for consistent dimensional accuracy. It complies with ASTM Grade C mechanical properties, ensuring tensile strength and performance reliability. The manufacturing process follows industry specifications for distorted top lock threads and right-hand thread direction, and the zinc yellow-chromate plating meets RoHS and REACH environmental directives for restricted substance control.