
- What is a zerk grease fitting?
- Where can I buy a zerk grease fitting?
- How do grease fittings work?
- What is the most common standard size grease fitting?
- How much grease should I put on a fitting?
- Can you over-grease a fitting?
- How to grease a zerk fitting
- What are the different types of grease guns?
- How to attach a grease gun to a zerk fitting
- How to remove a grease gun from a zerk fitting
- What size thread is used on a zerk grease fitting?
- How to replace a grease fitting with a grease fitting multi tool
- How to remove a broken grease zerk
- How to remove or free up stuck grease fittings
- How to install a drive type grease fitting
- How to remove a drive type grease fitting
- How to install self-tapping grease fittings
- How to grease a button head fitting
- How to extend grease fittings for hard to reach places
- What if my grease fitting won't take grease?
- How to clean a grease fitting
What is a zerk grease fitting?
A zerk grease fitting (also known as a grease fitting or grease nipple) patented by Oscar Zerk in 1929 is used in mechanical systems to feed lubricants like lubricating grease into a bearing using a grease gun. It was introduced as an improved method of lubricating moving parts. Zerk fittings are permanently installed on bearing housings or mechanical components to serve as a lubrication point to feed precise amounts of grease into bearings and other moving systems. Zerk fittings come in variety of types, such as
Drive In,
Rivet, and
Thread Forming. They can be manufactured using brass, stainless steel, and Monel® materials.
Where can I buy a zerk grease fitting?
Huyett offers its own complete private line of grease fittings and accessories at the lowest distributor price! We are also a Master Distributor for
Alemite®, Alemite Aerospace®, and
Lincoln® brands. In addition, we offer a complete line of metric and international grease fittings. If you don’t find what you are looking for, call us today to speak with our friendly, experienced sales team.
How do grease fittings work?
Grease zerk fittings work by acting as a one‑way check valve that allows grease to pass through one way, but not the other. Inside the fitting is a ball check suspended by a spring. As grease is pushed into the fitting, pressure is created against the ball check that compresses the spring allowing grease to pass completely through the fitting. When grease flow stops, the spring pushes the ball check back to its original position, closing the fitting and preventing grease to escape.
What is the most common standard size grease fitting?
The most common standard grease fitting size is 1/4"‑28 SAE‑LT and is often used in automotive applications. "SAE-LT" refers to a special thread that applies a taper to standard UNF threads. They can also be found in agricultural environments as well as other various standard duty applications. For heavy duty applications, larger 1/8"‑27 PTF zerk fittings can be found. PTF threads are physically larger than SAE-LT threads.
How much grease should I put on a fitting?
The amount of grease put in a fitting depends on the size of the part to which it is attached. As a general rule of thumb, apply grease until you begin to feel resistance while pumping. Do not apply grease until it seeps out of bearing seals or other components.
Can you over-grease a fitting?
Yes. Only apply grease until you begin to feel resistance while pumping. Do not apply grease until completely full or seeping out of the fitting or other components. Changes in temperature or pressure can cause the grease to expand causing further leaks, which can cause dirt, gravel, or other debris to collect on the exposed grease and work into the moving part, shortening its lifespan.
How to grease a zerk fitting:
While grease fittings themselves do not require grease, the part they are attached to does. To grease the part, attach a grease gun to the end of the zerk fitting and pump until you feel resistance. It is a good idea to refer to your equipment’s service manual for recommended maintenance practices when possible.
What are the different types of grease guns?
There are many different types and designs of grease guns, and we offer lever, pistol, cordless, and pneumatic grease guns. We have a gun for practically any application. Huyett offers the following on our site.
Lever Gun: Our standard lever gun is not only economical, but also provides the most volume per stroke as compared to other manual guns. A full range of interchangeable / customized features are available to suit your individual needs. ** Lever guns require two hands to operate. **
Pistol-Grip Gun: Pistol-grip grease guns are good for use in close-clearance areas. Using just one hand, grease is pumped via a simple squeeze. Pistol-grip guns typically dispense less grease per stroke than a standard two-handed lever gun.
Cordless Gun: Cordless grease guns use rechargeable Lithium-ion batteries for complete portability and ease of use. Huyett grease guns come equipped with a carrying case and two batteries for extended use. ** Cordless grease guns are trigger operated, portable, and convenient. **

How to attach a grease gun to a zerk fitting
- First, ensure both the zerk fitting and the grease gun coupler are clean and free of debris and other contaminates. This will help ensure a secure connection between the fitting and the coupler.
- Next inspect the fitting to ensure there is no damage. If the fitting is damaged, you may want to consider replacing the fitting before continuing.
- Once everything is clean and inspected, set coupler at an angle to fitting and while firmly pressing down, roll the coupler onto the fitting. You should feel the coupler clamp down on the fitting and click into position.
How to remove a grease gun from a zerk fitting
- Ensure that the pressure has been relieved between the coupler and the grease fitting.
- If this does not happen on its own, tilt the grease gun coupler to approximately 15 degrees to break the seal. You may see grease expel from between the coupler and the grease fitting.
- Once pressure is released, continue tilting the coupler past 15 degrees while at the same time twisting back and forth.
- This should safely disengage the coupler from the fitting.
What size thread is used on a zerk grease fitting?
There are several components of threads on a grease fitting.
- Thread series is the thread "style" of a given grease fitting. There are many different thread series and each has specific attributes. Thread series can be either SAE Standard (also called taper thread), American Standard, Unified National, or Foreign Standard.
- Thread size is the nominal size of pipe that the fitting mates with. Originally, the size referred to the inside diameter of the pipe at a time when pipes had very thick walls. That is why a 1/8" pipe has a 0.393" actual outside diameter. Huyett carries sizes ranging from 0.18" diameter to 0.820" diameter and 6.0mm to 16.0mm in metric.
- Thread pitch refers to the distance "peak-to-peak" of each thread. Imperial and British standards call out threads per inch, while Metric standards specify thread pitch in millimeters.

How to replace a grease fitting with a grease fitting multi tool
- Place the socket end of the tool over the grease fitting nipple so that the tool fits securely against the fitting's hex holds.
- If the socket end does not work, or the fitting is broken,, loosen the fitting by inserting the extractor bit into the center of the fitting. Drilling out the fitting may be required.
- Using the socket or extractor, rotate the multi tool counter clockwise to loosen the fitting.
- Continue to loosen the fitting until it is free from the mating component.
- Clean the threads of the mating component with the tap end of the multi tool.
- Thread the new grease fitting into the mating component by hand.
- Use the socket of the multi tool to finish tightening the grease fitting.
How to remove a broken grease zerk
- Locate an appropriately sized end wrench or use a grease fitting multi tool that fits the hex holds of the grease zerk.
- Position the tool around the hex shaped section of the grease fitting.
- Loosen the grease zerk by rotating it counter clockwise with the wrench.
- Continue to loosen the grease zerk until it is completely free of its mating assembly.
How to remove or free up stuck grease fittings
Stubborn grease fittings that are broken or unable to be removed with a socket or wrench can be removed using the extractor bit of a grease fitting multi tool.
- If necessary, begin by drilling a hole into the stubborn fitting to allow the multi tool's extractor bit to fit inside.
- Be careful not to drill completely through the fitting as this could deposit metal shavings or other debris into the attached part.
- Once the fitting is completely removed, clean the threads using the tap on the multi tool.
How to install a drive type grease fitting
- Ensure the grease fitting is the proper fitment for the hole to which it is being applied.
- Place a grease fitting drive tool over the top of the grease fitting.
- Place the shank of the grease fitting into the hole, ensuring it is perpendicular to the mating component.
- Tap the protruding end of the driving tool with a hammer to drive the fitting into the desired hole.
- Continue driving the grease fitting into the hole until it is seated securely in place.

How to remove a drive type grease fitting
- Use a slide hammer with a locking plier attachment to clamp to the end of the grease fitting.
- Operate the slide hammer with several solid strikes to loosen the fitting.
- Continue this action until the fitting is completely removed from its mating component.
How to install self-tapping grease fittings
Self‑tapping grease fittings, or thread forming grease fittings, can be installed using either a pre‑existing or freshly drilled hole.
- For new applications, start by drilling a hole into your part that is slightly smaller than the outside diameter of the grease fitting shank. It is encouraged to test fitment on a spare piece of material before permanently installing the fitting. For replacement, start on Step 2.
- Test fitment.
- Insert the shank of the fitting into the hole and begin tightening by hand while ensuring the fitting is perpendicular to the part it's being attached to.
- Use a grease fitting multi tool to finish the installation. Continue tightening until the grease fitting is seated securely against the mating surface of the part.
How to grease a button head fitting
Button head fittings are popular in rugged applications where damage to protruding grease fitting heads is likely to occur. These low profile fittings can be greased using a button head coupler. Pull the coupler over the head of the grease fitting and pump until you feel resistance.
- Ensure you have a button head coupler attached to your grease gun.
- Clean the button head grease fitting of any contamination or debris.
- Slide the button head coupler over the grease fitting so that the grease fitting is interlocked with the coupler.
- Begin pumping grease from your grease gun until the desired amount has been applied.
- Remove the grease coupler from the fitting by sliding away from the grease fitting.

How to extend grease fittings for hard to reach places
Grease fitting extensions are used to provide additional clearance for grease fittings in hard-to-reach areas. For more information, visit our
grease fitting adapters product page.
What if my grease fitting won't take grease?
If your grease fitting won't take grease, check the following:
- Is the fitting nipple damaged? If so, replace the fitting.
- If the fitting is not damaged, is the opening of the fitting obscured by dirt or other debris that could prevent grease from flowing into the fitting? If so, replace the fitting.
- If there are no contaminates, try using an unblocker tool to loosen any hardened grease that could be obstructing internal fitting passages.
How to clean a grease fitting
Grease fittings tend to collect dirt and debris. Using
grease caps is a preventative step in keeping grease fittings clean. However if grease caps are not in use, a lint free cloth can be used to wipe the fitting clean.
For clogged or blocked grease fittings, a grease fitting unblocker tool can be used. A grease fitting unblocker is specially engineered to quickly and easily unplug stubborn grease fittings. To operate, a light weight oil is injected into the tool’s reservoir. A plunger is then inserted and a tap from a hammer injects oil into the fitting, loosening the internal components.
