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 from 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 Grease Fitting?

By Jeremy Laukkonen
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 grease fitting is a small component that is designed to allow lubricating substances to be applied to bearings, joints and other moving parts. Ported orifices located in each grease fitting can allow pressurized lubricants to pass into a bearing but not escape. This design can also stop unwanted contaminants from entering a bearing or joint, which is a secondary but important function. Prior to the invention of the modern grease fitting, lubricating substances were typically pressed into place by hand or poured in, which can be more time consuming, less efficient and messier than application with a grease gun.

The first grease fittings, which were developed around the year 1916, used screw-on connectors. These early fittings were developed to allow the quick application of lubricating grease to all manner of bearings and other components. In order to accomplish this, a device known as a grease gun was also developed. The grease gun could be screwed on to a fitting and then used to fill a bearing with a lubricating substance very quickly. Later grease fitting designs performed this same function but were much smaller and did not require the screw-on connection.

Modern grease fittings are very similar to the original designs and typically consist of a small metal housing that has a cylindrical channel inside it. The channel contains a spring loaded ball that can keep grease in and contaminants out under normal circumstances. When an operator presses a grease gun onto a fitting and activates it, the pressure of the grease can overcome the spring tension and fill the bearing. This method of application is typically more effective than older techniques of packing bearings by hand, since the pressure tends to force the grease into hard to reach voids.

There are many different types of bearings and other components that can contain grease fittings, though automobiles are one common location that these parts are found. Some automobiles use sealed bearings that do not require any lubrication, while others have one grease fitting in every bearing and bushing in the suspension and steering systems. It is also common to find grease fittings in universal joints, drive shafts and sometimes even speedometer housings or cables. In some cases a vehicle will ship from the factory with plugs instead of fittings. Before the first lubrication service can take place on one of these vehicles, a new grease fitting must be installed in place of each plug.

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

By anon277069 — On Jun 27, 2012

Can you please share more information on grease fittings manufacturing process, like the method of inserting steel balls, springs and spring retainers?

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.