What is the primary feature of a carriage bolt?

• A. Square shoulders with a round head
• B. Fully threaded with a flat end
• C. Capable of self-drilling
• D. Hex head for increased torque

Answer: (A)

The primary feature of a carriage bolt is its unique design, specifically characterized by square shoulders that are found just beneath the round head. This design serves several important purposes. The square shoulders prevent the bolt from spinning when it is being tightened, allowing it to be easily secured with a nut or directly into wood. This feature is particularly beneficial in applications where a secure and stable hold is necessary, such as in wood connections in construction or furniture making.

In contrast, other types of bolts have different designs that serve other functions. For example, fully threaded bolts are used when a consistent grip along the entire length is needed, while self-drilling bolts are designed for ease of installation without pre-drilling holes, and hex heads provide increased torque through a wrench but do not feature the same design as a carriage bolt.