The grease gun is the first piece of equipment that all equipment operators should become very familiar with. The following article will point out a few tips that can make a tedious task easier and less messy.
When the gun is being used, the first indication it is empty or near-empty can be felt in the pump handle, it will have no resistance. Before we leap ahead and unscrew the end off the gun though, it is a good idea to confirm this assumption. On occasion a gun can lose its prime and feel empty when in fact it still has grease in the tube. To confirm its emptiness, grab the T-handle at the end of the gun and pull it back to check where the plunger is. If the plunger is at the top end then the gun is empty and the process of reloading a new cartridge can be initiated. If the plunger is not at the end then the gun is not empty and a different course of action is required.
The loss of prime is usually caused by an air pocket at the pump end of the gun. To cure this, unscrew the pump end a few turns being careful not to go too far and have it pop off. While it is in this loose position use the T-handle at the end of the gun to lock the bar in the plunger. This can be done by pulling back the handle and turning it so it is engaged in the plunger. Once it is locked press it firmly towards the top of the gun to push the trapped air out of the gun. You will probably feel the plunger move slightly. Try pumping the handle once again to see if the operation was a success. Repeat if necessary with more force or unscrew the end further until the gun re-primes.
Reloading the gun
To refill the gun the following steps should be followed. Firstly the pump end is removed from the gun. After the pump end is off the plunger can then be retracted to eject the empty tube and then retracted again and locked to accept the new full cartridge. It is important to remember not to retract the plunger while the pump end is still on the gun for two reasons - it will be much more difficult to draw the plunger back, and secondly, it draws the grease out of the pump which will make it harder to re-prime the gun when the new tube is started.
Be careful of how and where you place the pump end of the gun when you put it down. It should be set down so that no dirt comes in contact with the grease on it. A small piece of sand will go through the pump and end up lodged in the entrance to the grease fitting, blocking the flow.
To reload the gun pull the plastic end cap off the new tube, insert the open end into the gun and slide it all the way down until the pull tab end is flush with the top of the pump end of the gun. Pull the steel lid off the top of the tube and re-attach the pump end of the gun. Do not tighten the pump end down completely at this point. When you are confident it is on enough that it will not come off release the T-handle so the spring is applying pressure to the plunger, give the T-handle a push to assist the spring pressure so all the air will be forced out of the gun. Finish tightening the pump end of the gun and unlock the T-handle from the plunger and push it into the gun. You are now ready to begin greasing. Greasing can be made far less strenuous by storing the gun and the spare grease tubes in a warm compartment on the machine.
Greasing your piece of equipment can be far less tedious if these guide lines are followed. Removing air from the gun as well as keeping the interior free of all foreign material is extremely important. Care should also be taken to avoid denting the metal tube of the gun, if dented it can make it very difficult to eject the empty tubes from the gun.
One final tip about grease guns, I used to add a flex line between the gun and the metal tube. It makes it easier to push the coupler onto the grease nipple and it also keeps your gloved hand away from the grease.