S-91259A111 1/4"-20 ASME B18.3, ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Enhanced Load Distribution – The 3" shoulder length provides a precise bearing surface for rotating components, reducing wear and extending equipment life.
• Superior Tensile & Shear Strength – With 140,000 psi tensile and 84,000 psi shear strength, this screw withstands extreme mechanical stresses in demanding applications.
• Precision Thread Fit – Class 3A UNC coarse threads ensure tight, secure fastening with minimal backlash in high-vibration environments.
• Corrosion-Resistant Finish – Black oxide coating offers improved rust protection while maintaining dimensional stability.
• Optimized Drive Engagement – Hex socket drive (5/32") combined with knurled head prevents tool slippage during installation and removal.
• Hardened Material Performance – Alloy steel construction with Rockwell C32 hardness maintains thread integrity under repeated loading cycles.
• Standardized Dimensions – ASME B18.3 compliance guarantees interchangeability and reliable performance in OEM assemblies.

Professional Applications & Engineering Value

Engineered for precision alignment and rotational motion control, these shoulder screws solve critical positioning challenges in industrial machinery. The alloy steel construction and black oxide finish provide durability against corrosion and wear in automated systems. The 3" shoulder length acts as a precise axle or pivot point for gears, bearings, and linkages, while the UNC coarse threads and Class 3A fit ensure vibration-resistant fastening. Ideal for robotics, conveyor systems, and manufacturing equipment where socket head design facilitates maintenance in confined spaces. The knurled head enhances grip during manual adjustments, making these shoulder bolts essential for assembly lines requiring repeated disassembly.

Specification Summary & Compliance

This shoulder screw maintains Class 3A thread fit per ASME B18.3 specifications with UNC 1/4"-20 coarse threading. Shoulder diameter tolerance is controlled at -0.004" to -0.002" with length tolerance of -0.005" to 0.005". Manufacturing complies with ASTM A574 material standards and demonstrates full conformity to RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations.