Intro to Millwright Practice Exam

Which lock nut is approximately half the thickness of a standard hex nut and secures by distorting both nuts?

1. Jamb Nut

2. Lock Nut

3. Flange Nut

4. Square Nut

The correct answer is: Jamb Nut

A jamb nut is designed to be thin, roughly half the thickness of a standard hex nut, which allows it to be used in applications where space is limited. The primary function of a jamb nut is to secure another nut in place, preventing it from loosening due to vibration or movement. This is achieved by tightening the jamb nut against the primary nut on a bolt or threaded rod, effectively distorting both nuts and creating a strong mechanical lock that resists loosening. In contrast, a standard lock nut is typically thicker and may employ other locking mechanisms, such as nylon inserts or serrated edges, to prevent loosening without the same level of distortion. Flange nuts feature a wider base that provides increased stability and load distribution but do not function in the same way as a jamb nut. Square nuts are simply a different shape and do not carry the same specific application or locking properties as a jamb nut. Thus, the characteristics of a jamb nut make it uniquely suited for this role in securing both nuts through distortion.