We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is a Lock Nut?

By Dale Marshall
Updated May 17, 2024
Our promise to you
About Mechanics is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At About Mechanics, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

A lock nut is a type of nut that resists loosening when properly threaded onto a bolt. Nut-and-bolt fasteners are extremely common in industry and home applications, and finding an efficient, reliable lock nut is a priority for many. Many are universal in application, while others work best under certain circumstances. For instance, some of the most popular lock nuts have nylon inserts that increase the gripping force on the bolt, and are relatively impervious to vibration and corrosion; however, these lock nuts' capacity for re-use is questioned, and re-use is forbidden in some aerospace applications.

Nut-and-bolt fasteners are used to fasten together pre-drilled items, whether wood, plastic or metal. Nut-and-bolt fasteners are key components of much structural construction. Additionally, most machinery, including the engines that power transportation vehicles, relies on nuts and bolts to keep components fastened together. A universal problem with these fasteners is that over time, nuts will lose their grip on the bolt. This problem is exacerbated when machinery is involved, causing vibrations that hasten the loosening process. When nuts loosen, time is spent identifying the problem and correcting it. In addition, if the loosened nut caused other problems their solution will also involve expenditures of time and money. To solve the problem of nuts loosening from their bolts, lock nuts were devised.

One of the simplest lock nut applications, when there's sufficient space on the bolt protruding beyond the nut, is to tighten the nut and then thread a second nut onto the bolt, tightening it firmly against the first. Nuts that are specifically made for this purpose are thinner than regular nuts, and are called jam nuts. A jam nut will sometimes be used to secure a nut in place on a bolt where it's not secured up against the workpiece and some slack is desired.

Many applications, however, won't accommodate such ad hoc solutions, and many manufacturers produce specialized lock nuts to meet the demands of industry. Among the most popular of these is the lock nut with nylon collar insert. The nylon insert's diameter is slightly smaller than the bolt's diameter, and as the nut is threaded onto the bolt and tightened down, the nylon insert is deformed onto the threads of the bolt, increasing the friction between the nylon insert and the bolt threads, as well as between the threaded section of the nut and the bolt's threads.

Many lock nuts' efficacy is usually achieved by increasing the friction between the threads of the nut and the bolt. Interfering thread lock nuts and distorted thread lock nuts utilize this concept by deliberately making the nut and bolt inconsistent; the nut's diameter may be more oval than circular, or the opening may be tapered. In either case, as the nut is threaded onto the bolt, more friction exists between the two sets of threads, thus increasing resistance to loosening.

Another approach to resisting loosening is to provide resistance at the point of fastening, as in the case of a serrated face nut. The serrations are angled against the rotation of the nut when being tightened, and bite into the surface of the item being fastened. The work surface itself, then, provides resistance against loosening. These nuts should be used when the installation is intended to be permanent.

About Mechanics is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
About Mechanics, in your inbox

Our latest articles, guides, and more, delivered daily.

About Mechanics, in your inbox

Our latest articles, guides, and more, delivered daily.