S-91259A307 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 shoulder screw reliably handles high-stress applications without failure.
• Superior Corrosion Resistance: The black oxide finish provides excellent protection against rust and wear, extending service life in harsh industrial environments.
• Precision Thread Fit: Class 3A thread fit ensures tight, secure fastening with minimal backlash, ideal for applications requiring exact alignment and vibration resistance.
• Enhanced Grip and Handling: The knurled head offers improved grip during installation and removal, reducing slippage and speeding up assembly processes.
• High Durability and Hardness: Made from alloy steel and hardened to Rockwell C32, this screw maintains its integrity under repeated use and heavy loads.
• Easy Installation with Standard Drive: The 5/8" hex drive socket head allows for quick, tool-friendly installation using common wrenches, minimizing assembly time.
• Regulatory Compliance and Reliability: Meets ASME B18.3 specifications and is RoHS 3 and REACH compliant, ensuring safe, eco-friendly use in global markets.

Professional Applications & Engineering Value

This 7/8"-9 UNC shoulder screw is engineered to address critical challenges in heavy-duty industrial settings, such as machinery assembly, automotive systems, and precision equipment. The alloy steel construction, combined with a black oxide finish, delivers robust corrosion resistance and longevity, reducing maintenance costs in corrosive environments. Its coarse UNC threads and Class 3A fit provide secure, vibration-resistant connections, essential for applications where loosening could lead to operational failures. The shoulder diameter of 1 1/4" and length of 2" ensure precise alignment and spacing in assemblies, making it ideal for pivots, bearings, and rotating components. By integrating high tensile and shear strength, this screw supports demanding loads while the knurled socket head enhances usability, streamlining installation in tight spaces and improving overall efficiency in B2B procurement and manufacturing workflows.

Specification Summary & Compliance

This shoulder screw adheres to strict dimensional tolerances, including a shoulder diameter tolerance of -0.004" to -0.002" and shoulder length tolerance of -0.005" to 0.005", ensuring precise fit in engineering applications. It conforms to ASME B18.3 standards for socket head shoulder screws, with UNC coarse threads and a Class 3A thread fit for reliable performance. Additionally, it is compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, guaranteeing environmental safety and suitability for international industrial use.