Industrial grease can be purchased in cartridges and in bulk. The grease is applied using one of several types of grease guns. In most cases, they are filled the same way — either with a cartridge or from a bulk container.
Before we dive in, let’s point out a common error—using every bit of grease in a grease gun.
An error many people make is to pump grease until the cartridge is completely empty. This leaves your hose full of air and in need of being primed again. The trick is to pump until you are almost out of grease, leaving just a bit in the hose and in the head of the gun. To check the amount of grease remaining, pull down on the follower rod. The rod will stop when it hits the follower plate at the bottom of the grease and will indicate how much grease is remaining.
If You Have a New Grease Gun
When you buy a new grease gun, there is no grease in the hose, so you'll need to prime it to clear out all the air. Without grease already in the head of the grease gun, the piston is pumping air, and you may need to help push the grease up and out of the cartridge to get things moving.
Refilling a Grease Gun from a Bulk Container
There are two ways of bulk filling a grease gun. You can fill a grease gun from bulk containers or with a filler pump. First, let’s look at filling from a bulk container. You’ll need to prepare the cartridge for this procedure. This is done by removing the canister from the head. Now remove the end cap. Unscrew the end cap and slowly pull the piston out. You will see the piston’s seal pointing to the back of the gun. This is for a cartridge. To refill from a bulk container, you need to turn this seal around (flip it) so that it is facing frontward. After this is done, you reinsert it into the tube and thread the end cap back on (now the seal is pointing to the front of the canister). You’re ready to put the canister into a container/pail of grease--slowly pulling back on the piston rod, which creates suction—pulling the grease into the canister. You now have a full canister of grease.
If you are using a bulk container with a filler pump, the grease gun’s head and canister need to have a fitting so you can insert the quick disconnect into the filler pump. Once you connect the canister, you can manually fill the canister with the grease using the pump’s lever. These are the two ways of filling a grease gun from a bulk container. Remember, you must change the orientation of the seal to create that vacuum effect.
Changing a Grease Cartridge
You can also refill your grease gun using a new cartridge of grease. First, unscrew the cylinder one turn to make it easier to pull back on the plunger. Pull the plunger all the way back and lock it into place by tilting it towards the metal tab. Now finish unscrewing the cylinder. Remove and discard the old grease cartridge. Insert the new cartridge by removing its plastic cap (sliding the open end in the cylinder first). Next, remove the metal cover by lifting up on the middle tab and peeling it away. Screw the head assembly back on the cylinder. Turn the head assembly until it's tight, and then loosen it about one full turn. Press on the middle tab by the plunger and push the plunger back into the cylinder. Now, fully tighten the cylinder. You are finished!
Note: This applies only If you're using the same type of grease. If not, you'll need to pump the old type of grease out of the grease hose. Just pump until you see the new grease start to come out.