Intro to Millwright Practice Exam

What is the purpose of a lock washer in a fastening assembly?

1. To prevent rust

2. To distribute loads

3. To retain tension and prevent loosening

4. To improve aesthetics

The correct answer is: To retain tension and prevent loosening

The purpose of a lock washer in a fastening assembly is to retain tension and prevent loosening. Lock washers are designed to provide a form of mechanical locking that helps maintain the tightness of a nut or screw in situations that may experience vibration, movement, or thermal expansion. When a lock washer is installed, it exerts a spring-like force which creates additional friction between the fastener and the surface. This friction helps counteract the forces that might cause the fastener to loosen over time. Lock washers are particularly effective in applications where reliability and safety are crucial, as they help ensure that critical components remain securely fastened under operating conditions that could otherwise lead to loosening. This specific function distinguishes lock washers from other types of washers, which may serve different purposes such as distributing loads or preventing corrosion.