S-91670A539 1/4"-20 x 5/8" ASTM A574 Left-Hand Threaded Alloy Steel Socket Head Screws
Left-Hand Threaded Alloy Steel Socket Head Screws
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Basic Information
Head Parameters
Dimensions
Thread Parameters
Tip & Drive Parameters
Material & Strength
Temperature & Environment
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Key Features & Benefits at a Glance
- Exceptional holding power with 170,000 psi tensile strength for reliable performance in high-stress applications
- Superior corrosion resistance through black-oxide coating on alloy steel, extending service life in demanding environments
- Precise thread engagement with Class 3A fit and UNC coarse threads ensuring secure fastening in left-hand applications
- Optimized drive efficiency with standard hex socket and 3/16" drive size for easy installation and removal
- Enhanced durability with Rockwell C37 hardness maintaining structural integrity under repeated use
- Full regulatory compliance meeting ASTM A574, RoHS 3, and REACH standards for global industrial applications
- Reverse-thread reliability specifically engineered for applications requiring left-hand thread direction
Professional Applications & Engineering Value
These left-hand thread socket head cap screws solve critical reverse-rotation challenges in machinery, automotive, and industrial equipment where standard right-hand threads would loosen under counter-clockwise motion. The black-oxide alloy steel construction provides superior corrosion resistance while maintaining the 170,000 psi tensile strength necessary for high-vibration environments. Engineered with UNC coarse threads and Class 3A fit, these screws deliver precise thread engagement in soft materials and rapid assembly applications. The hex drive socket design allows for high-torque installation in confined spaces, making them ideal for maintenance-sensitive equipment requiring reliable reverse thread fastening solutions that withstand extreme operational demands.
Specification Summary & Compliance
Manufactured to exacting Class 3A thread fit tolerances with UNC coarse threads (1/4"-20) in left-hand direction. Full compliance with ASTM A574 specification for alloy steel socket head cap screws, ensuring consistent quality and performance. Meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations for safe use in international markets. The 5/8" length and standard socket head profile maintain dimensional consistency across production batches for reliable interchangeability.
