A carriage bolt is used to fasten metal to metal, wood to wood, and wood to metal. The head of a carriage bolt is round with a square neck under the head. The square neck functions as a locking device when inserted into a pre-drilled hole, designed to keep the head from turning as a nut is tightened. Carriage bolts can be manufactured from low and medium-carbon steel, as well as stainless steel.
A carriage bolt can be used extensively for security applications, particularly in the sign and fence industries, where the bolt must be removable from one side only or not at all.
Tanner carries two types of security nuts that can be used with a carriage bolt to create a tamper-resistant or tamper-proof fastener.
The Trident™ Nut is a tamper-resistant nut featuring a conical design that prevents unauthorized removal. It has three indented slots for installation and removal with a proprietary tool. Trident Nuts are tapped to standard bolt dimensions but can be tapped oversize to accept hot-dip galvanized fasteners (upon request). Trident nuts are manufactured from ZAMAK 5 zinc alloy and 316 stainless steel.
Break-Away nuts are suitable for applications where removal of a fixture is not intended. No special tool is required; break-away nuts are installed using a standard wrench. After tightening to the proper torque, the hex head breaks away, leaving a conical-shaped tamper-proof piece. Break-Away nuts are manufactured from Zamak 5 zinc alloy and 304 stainless steel.
The combination of a driver-less bolt and security nuts gives the installer double-action protection against theft and vandalism.