S-90185A638 3/8"-16 x 3 1/2" ASME B18.5, SAE J429 Carriage Bolts

Key Features & Benefits at a Glance

• Superior anti-rotation security thanks to the integrated square neck design, which locks securely into materials to prevent spinning during installation and under vibration.
• High tensile strength of 120,000 psi and a Grade 5 classification ensure reliable performance in demanding, heavy-duty applications.
• Corrosion-resistant zinc-plated steel construction provides a durable protective layer, extending the bolt's service life in various environmental conditions.
• Coarse UNC threading with Class 2A fit allows for faster, easier assembly and disassembly, reducing labor time and effort.
• Wide, rounded carriage head offers a larger bearing surface for enhanced load distribution and a finished appearance that minimizes snagging.
• Full compliance with major industry standards including ASME B18.5 and SAE J429, guaranteeing consistent quality, interchangeability, and engineering reliability.
• Rockwell C25 hardness provides excellent resistance to wear and deformation, maintaining thread integrity and fastener performance over time.

Professional Applications & Engineering Value

This Grade 5 zinc-plated steel carriage bolt is engineered to solve critical challenges in structural and heavy machinery applications. The square neck is a key feature, designed to embed into the connected material and provide superior anti-rotation security, eliminating the need for a separate lock washer and preventing loosening under dynamic loads and vibration. The coarse UNC thread ensures robust engagement in wood, metal, and other materials, making it ideal for construction, agricultural equipment, trailer assembly, and framing projects. The combination of a 120,000 psi tensile strength and a protective zinc plating delivers a reliable fastener that withstands high stress and resists corrosion, ensuring long-term structural integrity and reducing maintenance frequency in industrial environments.

Specification Summary & Compliance

This carriage bolt features a 3/8"-16 UNC thread with a Class 2A thread fit, ensuring standard dimensional accuracy for reliable assembly. It is manufactured in compliance with ASME B18.5 and SAE J429 specifications for Grade 5 fasteners. The product is also confirmed to be RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, meeting stringent environmental and safety regulations for hazardous substances.