S-91259A429 1/4"-20 ASME B18.3, ASTM A108 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional load-bearing capacity with 140,000 psi tensile strength for reliable performance in high-stress applications
• Superior wear and corrosion resistance thanks to the black oxide finish, extending service life in demanding environments
• Precise alignment and smooth rotation ensured by the Class 3A thread fit and standard shoulder fit, reducing assembly time and improving machine accuracy
• Secure, non-slip installation with the knurled head and 5/32" hex drive, allowing for high torque application without stripping
• Long-lasting durability from Rockwell C32 hardness alloy steel, maintaining integrity under repeated use and vibration
• Broad industrial compatibility with UNC coarse threads and 3 1/4" shoulder length, ideal for spacing, pivoting, and mounting components
• Regulatory peace of mind with compliance to ASME B18.3, RoHS 3, and REACH, ensuring safety and environmental standards are met

Professional Applications & Engineering Value

This shoulder screw is engineered to address critical alignment and durability challenges in industrial machinery. The alloy steel construction, combined with a black oxide finish, provides excellent resistance to corrosion and wear, making it suitable for harsh operational environments like automotive assemblies and manufacturing equipment. The precise 1/4"-20 UNC thread and Class 3A fit ensure tight, secure fastening, minimizing the risk of loosening under vibration. The 3 1/4" shoulder length with tight tolerances allows for accurate positioning of moving parts, such as in gears and pulleys, reducing maintenance needs and enhancing overall machine efficiency. Its socket head with knurled texture facilitates easy installation in confined spaces, streamlining assembly processes for engineers and technicians.

Specification Summary & Compliance

This shoulder screw features a 1/4"-20 UNC Class 3A thread with coarse spacing for secure fastening, and a shoulder diameter of 5/16" with tolerances from -0.004" to -0.002" for precise fit. The shoulder length is 3 1/4" with a tolerance of -0.005" to 0.005", ensuring consistent performance in applications requiring exact spacing. Manufactured to ASME B18.3 specifications using ASTM A108 material, it complies with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, guaranteeing adherence to environmental and safety standards for industrial use.