S-91259A851 5/8"-11 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 shear strength, this shoulder screw reliably handles high-stress applications without failure.
• Superior Wear and Corrosion Resistance: The black oxide finish on alloy steel provides enhanced durability and protection against rust in harsh industrial environments.
• Precision Alignment and Reduced Wear: The 4" shoulder with tight diameter and length tolerances ensures accurate component positioning and minimizes bushing or bearing wear.
• Secure Fastening with High Thread Reliability: Class 3A thread fit and coarse UNC threads offer excellent vibration resistance and easier assembly in demanding conditions.
• Easy Installation and Removal: The knurled socket head with 3/8" hex drive allows for quick, slip-resistant tightening using standard tools.
• Long-Term Performance in Heavy-Duty Use: Rockwell C32 hardness ensures the screw maintains its structural integrity and thread form over extended periods.
• Global Regulatory Compliance: Meets ASME B18.3, RoHS 3, and REACH standards, ensuring safety and environmental responsibility for international projects.

Professional Applications & Engineering Value

This shoulder screw is engineered to address common challenges in precision machinery and heavy-duty assemblies. The alloy steel construction, combined with a black oxide finish, provides excellent resistance to corrosion and wear, making it ideal for environments exposed to moisture, chemicals, or frequent movement. The 4" shoulder length with precise tolerances acts as a stable axle or pivot, reducing misalignment and extending the life of connected components like bearings, gears, and linkages. The coarse UNC threads and Class 3A fit ensure reliable fastening even under vibration, common in automotive, aerospace, and industrial equipment. By integrating high tensile and shear strength, this screw minimizes the risk of joint failure, supporting continuous operation in industrial applications where downtime is costly.

Specification Summary & Compliance

This shoulder screw adheres to strict dimensional standards, including a Class 3A thread fit for precise engagement and a shoulder diameter tolerance of -0.004" to -0.002" with length tolerance of -0.005" to 0.005". It conforms to ASME B18.3 specifications and is manufactured from alloy steel under ASTM A574. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring it meets global environmental and safety requirements for hazardous substance restrictions.