Structural Features Of Round Head Carriage Bolts

Round head carriage bolts, also known as round head square neck bolts, are fasteners with a round head (including small and large semicircular heads) and a square cross-section neck. They are used with nuts to connect parts with through holes.

Head Design: The head features a round or large semicircular shape with a smooth surface, which prevents hooking onto other objects. Compared with hex bolts, it reduces the protrusion height, making it suitable for spaces with limited clearance or where a smooth appearance is desired.

Square Neck: The neck has a square cross-section and fits into the square hole or slot of the connected part during installation, preventing the bolt from rotating while tightening and eliminating the need to secure it from the opposite side.

Threaded Rod: The rod portion has external threads, available in metric coarse, fine, and inch specifications, with diameters typically ranging from 5mm to 20mm and lengths from 15mm to 300mm.

Anti-Rotation and Anti-Theft: The square neck mates with the square hole to achieve self-locking, simplifying installation. The head has no internal hex or slotted drive structures, making it removable only from one side, providing a certain level of anti-theft protection.

Applications: Widely used in highway guardrails, marine aquaculture, wind power, wooden structures, marble dry-hanging, and other scenarios where preventing bolt rotation or one-sided installation is required.