Machine Design And Shop Practice (MDSP) Inhouse Practice Exam

Why are plain washers commonly installed beneath the head of a bolt or nut?

To distribute the load over a larger bearing surface To increase the effective thread engagement of the bolt To reduce the tightening torque required during assembly To increase the tensile strength of the threaded fastener

Correct Answer:

To distribute the load over a larger bearing surface

Explanation:

When you tighten a bolt or nut, the force is concentrated on a small bearing area under the head or nut. If that surface is softer or rough, it can indent or wear, reducing the clamping force and risking joint damage or fatigue. A plain washer spreads the load over a larger bearing surface, which protects the parts, prevents embedment, and helps maintain a steady clamp even if there are minor surface irregularities. It doesn’t change how much of the bolt’s threads engage, it doesn’t reduce the tightening torque, and it doesn’t increase the bolt’s tensile strength. So the main purpose is to distribute the load over a larger bearing surface.

Access more questions from this quiz

Continue to Machine Design and Shop Practice (MDSP) Inhouse Practice Exam for more practice questions and the full quiz experience.

Access More Questions