S-91259A301 7/8"-9 ASME B18.3 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional Load-Bearing Capacity: With a tensile strength of 140,000 psi and minimum shear strength of 84,000 psi, this screw reliably handles high-stress applications without failure.
• Superior Corrosion Resistance: The black oxide finish provides enhanced protection against rust and wear, extending service life in harsh industrial environments.
• Precision Thread Fit: Class 3A UNC coarse threads ensure tight, secure fastening with minimal backlash, improving assembly accuracy and reliability.
• Robust Material Construction: Made from alloy steel with Rockwell C32 hardness, it offers excellent durability and resistance to deformation under heavy loads.
• Secure Grip and Easy Installation: The knurled head and 5/8" hex drive allow for firm handling and efficient torque application, reducing installation time and slippage.
• Accurate Shoulder Alignment: Features a 1 1/4" shoulder diameter with tight tolerances, providing stable positioning for components in machinery and equipment.
• Compliance with Industry Standards: Meets ASME B18.3 specifications and RoHS/REACH regulations, ensuring safety, quality, and environmental responsibility.

Professional Applications & Engineering Value

This alloy steel shoulder screw is engineered to address critical challenges in high-stress industrial settings, such as machinery assembly, automotive systems, and heavy equipment. The 7/8"-9 UNC coarse threads with Class 3A fit deliver precise engagement, minimizing vibration-induced loosening and enhancing joint integrity. Combined with a black oxide finish, it resists corrosion in demanding environments, reducing maintenance needs. The 1 1/4" shoulder diameter and controlled tolerances ensure accurate alignment for rotating parts or spacers, preventing misalignment and wear. Ideal for applications requiring reliable high tensile strength and shear resistance, this screw supports efficient, long-lasting fastening in sectors like manufacturing, construction, and aerospace, where failure is not an option.

Specification Summary & Compliance

This shoulder screw adheres to precise dimensional standards, including Class 3A thread fit for UNC coarse threads and shoulder diameter tolerance of -0.004" to -0.002". It conforms to ASME B18.3 manufacturing specifications and is compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and quality assurance in industrial use.