S-91259A576 1/4"-20 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 for reliable performance in high-stress assemblies.
• Superior corrosion resistance provided by the black oxide finish, extending service life in demanding industrial environments.
• Precise alignment and reduced wear thanks to the Class 3A thread fit and standard shoulder fit, ensuring accurate component positioning.
• High durability and material integrity from alloy steel construction and Rockwell C32 hardness, resisting deformation under heavy use.
• Secure and efficient installation with a 5/32" hex drive and knurled socket head, preventing tool slippage and enabling high torque application.
• Broad compatibility with 1/4"-20 UNC coarse threads, making it suitable for a wide range of industrial machinery and equipment.
• Regulatory compliance and quality assurance by meeting ASME B18.3 standards and being RoHS 3/REACH compliant for safe, global use.

Professional Applications & Engineering Value

This alloy steel shoulder screw is engineered to address critical challenges in precision assembly and rotational applications. Its black oxide finish offers enhanced corrosion resistance, vital for operations in humid or chemically aggressive settings, while the Class 3A thread fit and precise shoulder dimensions—7/16" diameter and 3/8" length with tight tolerances—ensure minimal backlash and optimal alignment in industrial machinery, pivots, and cam followers. The UNC coarse threads facilitate quick assembly and disassembly, reducing downtime. With a socket head and knurled texture, it allows for secure hex drive engagement, preventing damage during high-torque installations. Ideal for precision shoulder screw uses in automotive, aerospace, and heavy equipment, this component delivers long-term reliability and performance under dynamic loads.

Specification Summary & Compliance

This shoulder screw adheres to Class 3A thread fit for high precision in UNC thread applications, with a thread size of 1/4"-20 and coarse spacing. Dimensions include a shoulder diameter of 5/16" (tolerance: -0.004" to -0.002") and shoulder length of 3/8" (tolerance: -0.005" to 0.005"), manufactured to ASME B18.3 specifications using ASTM A574 alloy steel. It is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and suitability for global industrial markets.