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Hot Dipped Galvanized Carriage Bolt Grade A

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Carriage Bolts are distinguished from other bolts by their shallow mushroom head and the fact that the cross-section of the shank, though circular for most of its length (as in other kinds of bolt), is square immediately beneath the head. This makes the bolt self-locking when it is placed through a square hole in a metal strap. This allows the fastener to be installed with only one wrench, working from the opposite end. The head of a carriage bolt usually is a shallow dome.

The carriage bolt is used extensively in security applications, such as locks and hinges, where the bolt must be removable from one side only. The smooth, domed head and square nut below prevent the carriage bolt from being gripped and rotated from the insecure side. Carriage bolts may also be used in the construction of docks, and decks as well as other surfaces where a smooth finish is needed.