S-91875A105 4-40 Cap Nuts

Key Features & Benefits at a Glance

• Superior corrosion resistance with zinc-plated steel construction, extending service life in harsh industrial environments
• Reliable fastening performance through Class 2B thread fit, ensuring consistent engagement and vibration resistance
• Quick installation and removal with external hex drive design compatible with standard wrench tools
• Enhanced durability from coarse UNC threads that resist stripping and cross-threading during assembly
• Secure end protection with closed cap design that prevents contamination and provides finished appearance
• Environmental compliance meeting RoHS 3 standards for safe use in regulated industries
• Precise dimensional compatibility with 1/4" width and height for consistent performance in inch-based assemblies

Professional Applications & Engineering Value

This 4-40 UNC coarse thread cap nut delivers exceptional engineering value where both protection and reliability are critical. The zinc-plated steel construction provides a sacrificial barrier against oxidation, making it ideal for industrial equipment, machinery, and outdoor applications exposed to moisture or chemicals. The Class 2B thread fit ensures smooth engagement with mating components while maintaining necessary clearances for production efficiency. The external hex drive allows for high torque application using standard tools, reducing installation time in high-volume assembly operations. The enclosed cap design not only prevents fluid ingress in hydraulic systems but also eliminates sharp edges for enhanced operator safety. These heavy-duty cap nuts are particularly valuable in automotive, electrical enclosure, and material handling equipment where vibration resistance and long-term performance are paramount.

Specification Summary & Compliance

This 4-40 UNC coarse thread cap nut features Class 2B thread fit per ASME/ANSI standards, ensuring proper clearance and interchangeability. Dimensions include 1/4" width across flats and 1/4" height with 5/32" thread depth for consistent performance. Manufactured from zinc-plated steel with right-hand thread direction and external hex drive style. Compliant with RoHS 3 (2015/863/EU) regulations under exemption 6(a)-I for lead as alloying element in steel, meeting international environmental standards for industrial components.