While it may seem like a nuisance to add grease to the fittings of large equipment and deal with the potentially messy job of how to load a grease gun, grease is the cheapest—by far—wear part in whatever equipment you’re using. Read this guide to learn how to load and use a grease gun.
If you own a tractor, zero-turn mower, utility trailer, boat trailer, motorcycle, or heavier piece of equipment like a loader, excavator, or dump truck/trailer you have fittings that need to be greased so they operate properly, but perhaps most importantly, do not fail during use and save you from costly repairs and wasted time.
Learn Where the Fittings Are
If you’re operating equipment commercially (even if that’s just a weekend lawn route), it is in your best interest to learn where all the fittings are on your machine(s) and to make sure they’re properly lubed. It’s minutes and pennies pro-action now versus a dollars, days, and downtime reaction later.
Once you locate all the fittings (called Zerk or Amelite) you’ll need to know how to load a grease gun then operate it safely and effectively. Compared to, say, remodeling a bathroom, this is an easy skill to acquire. But like any maintenance activity, it should be done with care.
Get to Know You Grease Gun
Think of a grease gun like a mash-up of a high-pressure caulk gun and a cordless drill. Grease is like caulk; really sticky, gooey, not-easy-to-clean caulk with packaging that can lay you open.
On the tool itself, there is a plunger, the tool body (or barrel), the actuator assembly (head), and a rigid nozzle or flexible hose at the end of which is a coupler that seats on the Zerk. Some crank open and closed like a cordless drill’s 3-jawed chuck catches a drill bit shank. Others are simply held on by hand-pressure. Which one works best for you is a matter of trial and error and preference.
Types of Grease Guns
There are lever-actuated grease guns, pistol-grip actuated grease guns and cordless battery-actuated grease guns.
For around-the-house use, pistol-grips are advisable at a mid-range price. You can hold the hose or nozzle with one hand and pump with the other. But in all cases, we’re talking about some pressure. Cordless grease guns are pushing at up to 10,000-psi.
Out of the box, the grease gun may have a flexible hose or a fixed metal tube. Both have their advantages and disadvantages in specific applications, and most mechanics and heavy equipment operators end up with at least one of each.
Steps for Loading and Using a Grease Gun
Similar to painting a room, chance favors the prepared grease gunner. You’ll need several rags handy, rubber gloves, and an easily accessible trashcan.
The grease selected matters a lot, a bad choice can get expensive.
- All grease is not of equal quality. Only use premium grease, it is the cheapest part in the machine no matter how much it costs per tube.
- Use the right grease for the job. In modern equipment, specialty lubricants are sometimes specified. Check with the manufacturer of the equipment you’re using to get the correct recommendation.
- DO NOT MIX GREASE TYPES unless you know what you are doing. Chemical incompatibility in lubricants can destroy bearings very quickly. Read more about determining grease compatibility, as well as this resource, to understand the concept in greater detail.
How to Load a Grease Gun
Most grease guns operate on the same principle mechanisms. Be sure to read and understand all the manufacturer’s directions before use.
- Pull the plunger back (there is a spring inside being compressed when you do this—this is important to know later; more on it below) and rest it on the catch in the tool body.
- Unscrew body from the head.
- If the gun has an old grease tube in it, remove the tube. If the tube is jammed carefully and slowly release the plunger to push the tube out. Re-latch the plunger once you can get a grip on the tube.
- Check that the gasket that seals the tool body to the actuator head hasn’t gotten buried in grease and thrown away with the old tube.
- On the new tube, remove the plastic cap and insert the tube into the tool—open end toward the plunger.
- Remove the pop-top or foil. This lid is astonishingly sharp, be mindful.
- Re-assemble the tool.
- For tools with no bleeder valve, the unit must be primed, or burped, to get any air out. Thread the unit back together and back it off one turn. Release the plunger. You may actually have to push it down through the grease. Tighten the tool and dispense grease onto a piece of cardboard until it flows burp-free. If the handle doesn’t resist the pressure you put on it, there is air in the tool. Keep pumping until the flow is uninterrupted.
- For units with bleeder valves, the air can be evacuated through the valve.
How to Use a Grease Gun
Always clean off the Zerk fitting with a rag before putting the grease gun coupler on it or you are pumping contamination into the bearing assembly.
A Zerk is a combination ball valve and check valve. The grease gun depresses the ball (tiny ball bearing) allowing grease to pass. When you remove the tool a spring pushes the ball back into the opening, sealing it. If the bearing doesn’t return and grease leaks out, there may be particulate matter obstructing its proper operation and you should get a new Zerk.
Under normal use, pump in enough grease that you hear escaping pressure and see just a little bit of grease movement squeeze out of the assembly. Basically, you’re replacing the old grease with new grease.
Don’t just keep pumping in grease, however. You may also check with your equipment dealer’s service department about tips for how best to grease the fittings. Wipe off any excess grease.
If the wheels are submerged in water (like boat trailers) it’s better to install a hub greasing system like Bearing Buddy, which makes maintenance easier.
Any time you are greasing something that has a pinch point or can fall (especially dump trucks and booms on equipment), either have them in the lowered position or propped up with an approved strut to avoid injury.
Even the best grease guns will eventually leak at the plunger. If you try to pull back on the plunger and it doesn’t move easily, stop. This probably means that grease is behind the plunger seal, and if you persist, that grease will come out the back of the gun all over you and the shop floor.
Go over to the trash can, get some clean rags handy, unscrew the cap over the trash can, and set the cap aside. Pull the plunger back over the trash can so the grease behind the plunger goes there.
Now you can reload as mentioned above.