Intro to Millwright Practice Exam

Which type of bolt is frequently used in heavy structural applications and requires washers for load distribution?

1. Lag Bolt

2. Coach Bolt

3. Carriage Bolt

4. Eye Bolt

The correct answer is: Lag Bolt

In heavy structural applications, the use of bolts that can handle high loads and provide effective load distribution is crucial. Lag bolts, also known as lag screws, are specifically designed for such tasks. They are large and have a coarse thread that provides a strong grip in wood, metal, or other materials, making them ideal for load-bearing connections in heavy structural setups. The requirement for washers with lag bolts enhances their effectiveness, as washers distribute the load over a larger area. This helps prevent damage to the surface material and minimizes the risk of the bolt loosening over time due to the dynamic forces at play in structural applications. While other types of bolts, such as coach, carriage, and eye bolts, have specific uses and characteristics, they do not typically suit heavy structural requirements in the same way that lag bolts do. Coach bolts are used predominantly in wood applications, carriage bolts are designed for smooth surfaces with a rounded head that is often used in connection with a nut, and eye bolts are mainly used for lifting or anchoring, not load distribution in heavy structures.