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Today, several technologies exist for the relubrication of machine components. A grease gun is one of the most common. The purpose of the grease gun is to apply lubricant through an orifice to a specific point, usually with the aid of a special fitting.
Grease guns are manufactured for a number of different applications, and the most common styles include lever, pistol-grip, hand-grip, air-powered and battery-powered models. The lever style is the most economic and, therefore, the most widely used of all the grease guns.
One of the most overlooked and under-credited tools in a maintenance shop, a single grease gun can bring an entire manufacturing facility to its knees if used improperly. A basic step that is often overlooked is training the lubrication technician on the proper use of the grease gun.
A high-pressure grease gun can deliver pressures up to 15,000 psi. Can you imagine putting a bearing on the shop floor and introducing 15,000 psi to the outer shield or race before installing it into a new piece of equipment?
I would hope not, but this is exactly what can happen the first time an untrained technician connects the gun to the fitting. Also, most bearing seals will rarely handle more than 500 psi. A grease gun in the hands of an untrained technician will compromise the bearing’s seal, leading to an early machine failure.
Lubrication technicians also need to know the output per stroke of the grease gun in order to know how much grease is added each time a piece of equipment is lubricated. Grease guns vary in the amount of grease pumped per stroke, from one to three grams of grease or higher.
Some manufacturers will indicate the maximum pressure and strokes per ounce on their product. If not, it is very easy to calibrate one yourself. All you need is a postal scale and the gun in question.
Another factor to consider is the type of grease fittings used in the facility. The most common fitting is the hydraulic fitting. These fittings have a ball check in the head of the fitting which prevents dirt from getting to the bearing. The spherical contour of the fitting head provides a ball-and-socket joint between the fitting and the hydraulic coupler of the grease gun.
They are available in threaded, thread-forming, rivet and drive styles. They are available in different angled configurations and a wide variety of extension lengths to allow you to position the fitting for easy access with a grease gun on different types of equipment.
Other common types of fittings include button head, flush (where protruding fittings cannot be used), pin, pressure relief and vent. There are also hydraulic shut-off fittings that shut off at specified pressures to prevent over-lubrication and blowing out bearing seals. Each application needs to be examined to determine the correct fitting and which style of grease gun and coupler is needed.
Some factors to consider when establishing standard grease guns for your facility include:
How are you going to load the grease gun – suction fill, cartridge or bulk?
What are your common lubrication quantities? You do not want a high-volume grease gun for areas requiring only a few grams of grease for lubrication tasks.
Some common tips for using a grease gun:
Calculate the proper amount of grease needed for relubrication of bearings based upon the calibrated delivery volume of the selected grease gun.
Use a vent plug on the relief port of the bearing to help flush old grease and reduce the risk of too much pressure on the bearing.
Use extreme caution when loading grease into the grease gun to ensure that contaminants are not introduced. If using a cartridge, be careful when removing the metal lid so that no metal slivers are introduced into the grease.
Make sure the grease gun is clearly marked to identify the grease with which it should be charged. Do not use any type of grease other than that which is identified.
Always make sure the dispensing nozzle of the grease gun is clean before using. Pump a small amount of grease out of the dispensing nozzle, then wipe the nozzle off with a clean rag or lint-free cloth before attaching it to the grease fitting.
Clean the grease fitting of all dirt before attaching the grease gun. Inspect and replace damaged fittings. It is helpful to use grease-fitting caps to keep them clean, but still wipe fittings clean before applying grease.
Ensure that the proper grease is used at every grease point. Applying the wrong grease can cause an incompatibility problem which can quickly cause bearing failure. Lubrication points should be clearly identified with which grease is to be used. This can be done with colored labels, adhesive dots or paint markers.
Grease guns should be stored unpressurized in a clean, cool, dry area and in a horizontal position to help keep the oil from bleeding out of the grease. Grease gun clamps make storage easy and organized. Also, cover the coupler to keep it free from dirt and contaminants.
Calibrate grease guns regularly to ensure the proper delivery volume.
Grease guns play a huge role in industry. They have a few disadvantages that are greatly magnified in the hands of untrained personnel, but have a few great advantages over automated lubrication.
The advantages include: low cost, ease of use once the technician is properly trained, and allowing the technician to inspect the equipment during lubrication tasks. Just remember not to overlook the basics, no matter how simple these may seem.
“Pathway to Progress: The Alemite Story” Stewart-Warner Corporation. Chicago, 1965.
Morgan, Stan. “Grease Guns – Learning the Basics.” Machinery Lubrication magazine, March 2002.
Sabrin Gebarin, Noria Corporation, “Grease Gun Buyers Guide”. Machinery Lubrication magazine. March 2004.