S-91259A906 3/4"-10 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional load-bearing capacity with 140,000 PSI tensile strength and 84,000 PSI minimum shear strength, ideal for high-stress industrial assemblies.
• Superior corrosion resistance thanks to the black oxide finish, extending service life in harsh environments.
• Precision Class 3A thread fit ensures tight, reliable fastening with minimal backlash in critical applications.
• Knurled socket head provides enhanced grip for easy installation and removal, even in oily or gloved conditions.
• Robust alloy steel construction with Rockwell C32 hardness offers excellent wear resistance and durability.
• Accurate shoulder dimensions (1" diameter, 4 1/2" length) with tight tolerances for precise alignment in machinery and pivots.
• Compliance with major standards including ASME B18.3 and ASTM A574, ensuring consistent quality and reliability.

Professional Applications & Engineering Value

This alloy steel shoulder screw is engineered to address common industrial challenges such as misalignment, high cyclic loads, and environmental wear. The black oxide finish provides a protective layer against rust and corrosion, making it suitable for automotive, aerospace, and heavy machinery applications where exposure to moisture and chemicals is frequent. The UNC coarse thread and Class 3A fit deliver secure, vibration-resistant connections, while the precisely machined shoulder acts as a reliable pivot or spacer in assemblies. Its high tensile strength and Rockwell C32 hardness ensure it withstands extreme forces without deformation, reducing maintenance downtime and enhancing operational safety in demanding industrial environments.

Specification Summary & Compliance

This shoulder screw features a 3/4"-10 UNC Class 3A thread with coarse spacing and a right-hand direction, manufactured to ASME B18.3 standards. The shoulder diameter is 1" with a tolerance of -0.004" to -0.002", and the shoulder length is 4 1/2" with a tolerance of -0.005" to 0.005". It complies with ASTM A574 for material specifications and meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring it is free from hazardous substances for safe industrial use.