I was once asked, “Why are lubricants so different? Why can’t we simply buy a ‘one fits all’ oil and grease?” I explained that the old farmers’ axiom, “Oil is oil, any oil will do,” may have had some merit 100 years ago, but it doesn’t now.

In today’s world of sophisticated machinery and the never-ending demand for asset reliability and availability, lubricants have evolved into multi-function, engineered products. They’re as much a part of a machine’s design as its electrical or mechanical systems. Choosing the correct lubricant has become an important and informed decision.

Today’s lubricants aren’t just oils – they’re precision-engineered components designed to make machines last longer, run cooler, and perform smarter.

Whether in the form of a liquid, solid, or gas, modern lubricants truly are pure liquid engineering. By blending additives into different base stocks, lubricants can be designed to perform up to eight simultaneous functions, enabling them to operate in a variety of environments and working conditions.

A Lubricant’s Job

Webster’s Dictionary describes a lubricant as “a substance (e.g., oil, grease, or soap) which, when introduced between solid surfaces that move over one another, reduces resistance to movement, heat production, and wear by forming a fluid film between the surfaces.”

In short, the job of a lubricant is to separate, control, and minimize the sacrificial and harmful effects of moving surfaces passing over one another under load, and at speed. It does this in the following eight definitive ways:

Function 1: Control and Minimize Friction

The primary function of every lubricant is to control and minimize the effects of friction.

When two solid surfaces pass over one another and come into contact under load, they “rub” together, producing dry friction that requires considerable energy to keep the surfaces moving. If no lubricant is present to separate the moving surfaces, they will quickly heat up to a temperature where they can weld or lock together, resulting in a mechanical “seize.”

If enough power is available, the two surfaces can be “torn” apart, resulting in surface degradation and wear debris. Movement will continue until the surfaces eventually weld together (seize) permanently, causing the power source to stall and the machine to fail catastrophically.

The introduction of a lubricating film between the two wear surfaces is intended to create a full fluid film barrier (with a thickness of approximately 5 microns), that’s designed to separate and prevent surface-to-surface contact.

Although a small amount of fluid friction is generated within the lubricant film, the energy required to move the surfaces over one another is but a small fraction of that required to overcome the surface-to-surface friction developed in the absence of a lubricant.

Function 2: Control and Minimize Wear

Note that a full lubricant film may not always be possible, and some metal-to-metal contact may occur under conditions of slow-moving, oscillating, heavy load, and lubricant loss. For these reasons, anti-wear additives that function as chemical “softening” agents on metal surfaces can be added to a lubricant.

The lubricant chemistry is designed to coat metal surfaces with soft layers of metallic salts, including sulfides and phosphate additives. As the surfaces slide over one another, alternating load cycles can cause the softened high points (asperities) on each surface to collide with each other when the film thickness is reduced.

When the protective film breaks down, microscopic welds form and tear apart – creating the wear debris that silently destroys machine surfaces.

If the unit loading exceeds the sulfur phosphide film, a rupture can occur, leading to a small metal-to-metal contact area. Localized heat then builds up, causing the two surfaces at the high point to “weld and break,” resulting in a micro-metal-particulate break, or asperity release, into the lubricant film.

Many lubricants are designed to control wear by promoting micro-surface degradation, allowing asperity “tips” to be sacrificed easily without “tearing” the parent metal. This controlled sacrificial process is designed to occur during the machine or bearing’s initial “break-in” period, thereby minimizing any continued surface wear under varying lubricant-film conditions.

Function 3: Control and Minimize Heat

When friction and wear levels are controlled and minimized, the amount of frictional heat produced is significantly reduced. Excessive heat can “cook” most lubricants, causing them to oxidize and become less effective. To combat this, antioxidant additives are added to the lubricant base stock.

Recirculating oil-system and air/oil system designs take advantage of a lubricant’s ability to absorb and transfer localized heat buildup at a bearing load point and, therefore, prevent any thermal runaway at the bearing surfaces. To facilitate the heat transfer/cooling process in recirculating systems, the oil may be pumped through a heat exchange unit (oil cooler), and/or reservoir baffle system upon return to the reservoir.

Function 4: Control and Minimize Contamination

As described above (in Function 2), a lubricant can become contaminated when wear asperities are introduced into the lubricant. Other forms of contamination, such as silica (dirt) and water, can be introduced through the reservoir filling process (when proper storage, transfer, and cleanliness practices aren’t followed) or enter the system when seals become compromised.

To combat solids contamination, a combination of detergent and dispersant additives can be added to the base oil. Detergents ensure that hot metal surfaces stay clean while neutralizing any acids that form within the oil. Dispersants help keep particulates and engine-soot colloidal suspended in the lubricant, ready to be extracted under pressure by an in-line system oil filter.

However, care must be taken to ensure oil filters are changed regularly. Regular filter changes prevent a contaminated lubricant from acting as a “lapping” paste, which can accelerate the wear process in bearing areas.

In the case of water contamination, emulsifier additives are added to allow the moisture to coalesce, separate from the oil, and settle in the reservoir. This allows easy drainage.

Lubricants are also used to seal out contamination ingress around shafts. A good example of this can be seen in a labyrinth seal, which uses the lubricant to fill a series of annular grooves cut into the non-moving shaft housing, thereby acting as a live shaft seal.

Function 5: Control and Minimize Corrosion

While oxygen may be a basic human life force, it can be fatal to a lubricant. When present in lubricants, oxygen acts as a catalyst to combine certain metals and organics, generating corrosive acids harmful to the bearing surfaces. If the wear surfaces are ferrite (iron) based, the acids will attack the metal and form rust on the bearing surface.

Most lubricants are designed to “cling” to metal surfaces and prevent moisture and oxygen from reacting with them. But all lubricants aren’t formulated the same way. Consequently, if bearing surfaces are iron-based, a lubricant with anti-corrosive additives must be employed to neutralize the corrosive acids and form a protective skin on the metal surfaces.

Function 6: Control and Minimize Shock

Most RAM professionals will be familiar with the quieting effect of adding a lubricant to a gear train. In such a case, the lubricant acts as a hydraulic shock absorber between mating gears as they mesh. Poorly lubricated meshing gears set up shock waves as they start to mesh, resulting in a “chattering” sound that can fracture the gear teeth.

A well-lubricated gear train doesn’t just run smoother – it absorbs shock, quiets operation, and prevents destructive chatter.

The same issue can occur in the cars and trucks we drive: In fact, the word “shock absorber is synonymous with automobile suspension systems that employ hydraulic oil to dampen and absorb the effects of road shock on a vehicle.

Function 7: Control and Transmit Power

In a typical hydraulic system, oil is used to transmit force and motion from a single source (usually a pump) into multiple system components, including pistons and accumulators, among others. Hydraulic oil is also used to transmit power in soft-start devices, such as fluid couplings, automatic transmissions, and torque converters.

Function 8: Control and Minimize Energy Consumption

Effective lubrication practice dictates the use of the Right lubricant, in the Right place, at the Right time, in the Right amount, using the Right method. Doing so will ensure the asset uses the least amount of energy, especially concerning moving parts.

In studies conducted on behalf of various electric-power companies, effective use of lubricants, delivery systems, and lubrication methods resulted in an energy reduction of 7.5% when a synthetic-lubricant product replaced a standard compressor oil. A 17.92% energy reduction was achieved on a stamping press when the automated-oil-delivery system was “tuned” and a more appropriate oil was chosen.

The Takeaway: Why Lubricants Matter More Than Ever

Lubricants are much more than oil and grease. They’re complex, engineered products that can be tailored to meet various working situations, ensuring asset reliability and long lifecycles.

If you haven’t done so in the last two to three years, ensure your plant’s equipment assets receive the best protection lubricants can offer: Work with a professional lubrication consultant to conduct a lubrication effectiveness/consolidation audit.

A saying warns, “There are none so blind as those who do not see.” That adage has both literal and metaphoric meanings regarding maintenance inspections. It’s no secret that visual acuity deteriorates as we get older. According to the Illuminating Engineering Society (IES), once a person reaches the age of 65, they will require twice the illumination that a 25-year-old routinely needs.

There was a time when regular owner inspection was an integral and expected part of vehicle ownership and the operator experience. Automotive companies often provided owners with portable 6V or 12V inspection lamps as part of their onboard tool kits. Now, modern cars and trucks perform their own onboard diagnostics and tell their owners/operators when to take them in for professional inspections.

Machine inspection is the most basic of all preventive maintenance work. Inspection compares the machine’s current state condition against a known “normal” or “as new or designed” condition state to determine if deterioration that requires repair has occurred.

The Role of Lighting in Maintenance Inspections

Although inspection can be diagnostic-based, using specific tools, it remains a visual act that is often best performed while a machine is running under full design load.

Because equipment is designed and built, bearing points or moving linkages are often poorly lit or inaccessible in running machines. In such cases, an expensive Lock-Out/Tag-Out production shutdown is required to perform a full inspection PM. If production access isn’t granted, the PM will often be closed incomplete.

A quality asset inspection relies on access and good-quality lighting in all cases.

A quality asset inspection relies on access and good-quality lighting in all cases. For maintenance departments with open minds, modern consumer technology now provides a very bright and inexpensive perspective for maintenance inspections of running equipment.

Affordable Technologies for Enhanced Inspections

We’ve come a long way from the old car flashlight. Today’s hand-held and head-band-mounted super bright LED lights with focusable beams can provide extremely high illumination of machine dark spots from greater distances than ever before. For inspection of machines with inaccessible, hidden areas, inexpensive, switchable LED strip lighting can be permanently installed to provide illumination, allowing the use of miniature Wi-Fi-actuated security cameras (such as those in today’s doorbells) that can be turned on with a smartphone (refer to my column, “Why Your Smartphone is the Most Powerful Tool in Your Maintenance Kit“).

Wi-Fi cameras can be permanently installed and monitored in high, out-of-reach areas.

Wi-Fi cameras can be permanently installed and monitored in high, out-of-reach areas, such as cranes, gantries, and rooftop HVAC equipment. When Wi-Fi isn’t available, initial inspection can be done with a high-magnification monocular/binocular coupled to a smartphone camera. For out-of-visual-sight equipment, maintainers can be trained to use inexpensive drones.

As for controlled or confined space areas that require shutdown, consider using a small Remote Control (RC) robot with a mounted Wi-Fi or smartphone camera. Many hobby shops sell excellent RC cars with cameras or RC chassis kits that can be converted to carry small cameras or smartphones.

If an inspection finds a potential problem, a permit can be sought for further physical inspection/repair. Internal inspections behind walls or engine- and gearbox-cavity inspections can be done using inexpensive camera-inspection tools purchased from a hardware store.

Given their capabilities, the technologies described here can all provide irrefutable permanent records of inspection that can be both time and date-stamped for proof and state of repair. Bottom line: All of them can open our eyes and allow us to see our machinery in a new light.

In 1966, at the height of the “swinging sixties” movement, the world of lubrication, friction, and wear finally received worldwide recognition as a scientific entity responsible for continued machine health and asset longevity.

In retrospect, such recognition was long overdue, considering the practice of applying lubricants to moving surfaces to reduce friction and surface wear is now recognized to be over 5,000 years old.

This fact was substantiated by the discovery of some archaeological evidence in the East Asia Tigres-Euphrates river system, i.e., wooden cart wheels and wheel-bearing material thought to have been lubricated with water, tallow, or beeswax (Jenkins, 1980).

I discussed that finding with a colleague, which eventually led to an exercise that came up with a “Top 10” list of pioneers in the lubrication field.

Most people would consider this a challenge, but many true pioneers are worthy of mention in the fields of lubrication, friction, and wear. The following list reflects my ten personal, gold-medal “Lubrication Hero” choices, in chronological order, starting back in the 1600s.

1. Sir Isaac Newton

Newton was an English Physicist, mathematician, and scientist who lived from 1643 to 1727. Famous for describing gravity and the three laws of motion, he was the first to recognize surface friction as an external force.

2. Elijah McCoy

The Canadian-born McCoy worked as an oiler for the Michigan Central Railroad when he invented the world’s first patented, self-pressurized oiling device. It used steam from a locomotive engine to force-feed lubricant to various points automatically. The design worked so well that railroads shunned all competitive products and only wanted to purchase McCoy’s lubricator. This, in turn, led to the coining of the phrase, “It’s the real McCoy!”

3. Richard Stribeck

Stribeck was a German engineer who 1902 first described changes in the friction coefficient of bearings as they experienced different lubricant regimes (Boundary, Mixed film, and Hydrodynamic) from startup to full running. He graphically represented these changes in what is now known as the “Stribeck Curve” diagram.

4. Arthur Gulborg

Driven by the repetitive task of manually refilling oil cups of the die-cast machines in his family’s business, Gulborg was motivated to develop a less taxing process that employed a new grease-lubricant medium. The result was the world’s first grease gun, which featured a screw-type design built to mate up to a proprietary bearing point fitting. Gulborg called his invention the “Alemite” high-pressure lubricating system, after his family business.

5. John R. Battle

Battle was a U.S.-born engineer who, in 1916, penned The Lubrication Engineers Handbook. Four years later, he published the encyclopedic Handbook of Industrial Oil Engineering.

A prolific inventor of all things lubrication, his “Gun-Fil” system is still sold today. The International Council of Machinery Lubrication (ICML) presents an annual award in Battle’s honor that recognizes best-practice machinery lubrication programs.

6. Joseph Bijur

Until 1923, automobiles required a rigorous daily lubrication schedule to lubricate up to 50 chassis lubrication points.

To alleviate this burden, the American inventor Bijur developed a self-contained engineered pump and the world’s first centralized lubrication-delivery system for oil, which he called a “single line resistance (SLR)” system. His namesake company still exists today, and the SLR system remains the most copied and highest-selling lubrication system ever.

7. Oscar V. Zerk

Zerk emigrated from Austria to the United States and became a prolific inventor (with over 300 inventions to his credit).

His most famous contribution to the world of lubrication manifested itself as the now-famous, patented “Zerk” push-style grease fitting that has been unchanged since 1929. By the time he died in 1968, more than 20 billion zerk grease fittings had been manufactured.

8. August H. Gill

A U.S.-born chemistry graduate of MIT in 1884 (at the tender age of 20), Gill made his mark as a founding member of the ASTM committee for petroleum products and lubricants.

More importantly, he’s credited as the founding father of oil analysis (having been one of the first to formalize it as a field of study). The ICML presents an award in Gill’s honor to recognize organizations that exhibit excellence in applying used oil analysis and lubricant-condition monitoring.

9. Sir Peter Jost

Funded by the British Ministry of State for Education and Science, Jost was tasked to investigate the position of lubrication education and research in the United Kingdom and give an opinion on industry needs in this field.

This assignment led to a landmark study of the measured effects of friction, lubrication, and wear on the British economy. Jost coined the term “Tribology” and introduced it to the scientific and industrial world. For this contribution, he received a knighthood.

The resulting Jost report was then used as a model for further studies in the U.S., Canada, and Germany. All of them echoed similar results that highlighted the importance and effectiveness of lubrication.

10. Ernest Rabinowicz

As a Professor of Mechanical Engineering at MIT, Rabinowicz followed up on Sir Richard Jost’s study with his ground-breaking study on “Design, Friction, and Wear of Interacting Bearing Surfaces.”

This study led to Rabinowicz’s seminal tribology book, Friction and Wear of Materials. He is also credited as the author of the “Rabinowicz Law,” which states: “Every year 6% of the GDP—Gross Domestic Product—is lost through mechanical wear.”

We must understand who from the past (and how the past) helped shape our modern-day approach toward lubrication practice and management. I have admired the above lineup for many years and believe that all those listed are worthy of note in the tribology field.

Initially published in The RAM Review

The lowliest and most ubiquitous device in the world of lubrication recently celebrated its centennial anniversary. Designed as a simple yet efficient mechanical gateway device, the grease nipple has only one job: to connect to a manual grease-delivery gun and provide protected one-way access to the bearing cavity for filling purposes.

Some Lubrication-World History

Before Arthur Gulborg invented the grease gun in 1918, a bearing was lubricated individually using a grease cup device. The grease cup, aptly named, resembled a large thimble-sized reservoir sitting above the bearing entry point. The reservoir, or grease cup, had a screw-in lid that, upon removal, allowed grease to be manually paddled in place.

Before Arthur Gulborg invented the grease gun in 1918, a bearing was lubricated individually using a grease cup device.

Once filled, the lid was partially screwed back in place. In doing so, the screw-in action would mechanically force new grease into the bearing.

As the machine continued to run, the operator or designated lubricator would, at regular intervals, screw in each cup lid another few turns to re-lubricate the bearing with more grease. This time-consuming effort would repeat until the cup was empty and required manual refilling.

While working for the Alemite Die Casting and Manufacturing Co. in Chicago, IL, Gulborg ensured all machine-lubrication cups were operated correctly and regularly filled.

Recognizing an opportunity for increased efficiency, he designed the first-ever pressurized grease gun that could be directly coupled to the grease fitting, making the grease cup obsolete.

He named his design the “Alemite High Pressure Grease System.” When it was adopted in 1918 as the greasing standard for the U.S. Army, the company made a fortune.

By 1922, Gulborg’s grease-gun design had evolved into a Push/Pump-style device that could be placed against his newly designed button-head, compression grease fitting. This type of fitting opened under the grease-gun pressure, allowing the lubricant to flow through to the bearing point.

But, as it did not afford a positive “lock on” connection, the grease-gun operator had to use both hands to keep the end of the gun positioned square to the grease fitting’s face. (That was the only way to prevent grease leakage from occurring.)

At the same time, in Kenosha, WI, an eccentric Hungarian immigrant named Oscar Ulysses Zerk was busy inventing a simple nipple-shaped, spring-activated, high-pressure grease fitting. The result of Zerk’s efforts was destined to take the lubrication world by storm.

All the while, Gulborg and the Alemite Co. continued developing their high-pressure grease system. They soon introduced a hand-trigger-operated grease gun that connected to the first positive-lock grease nipple (referred to as a “pin-type grease fitting.”)

By 1922, Alemite’s new system was successfully being promoted and used on mass-produced automobiles. (Alemite’s pin-type grease fitting is still used wherever a guaranteed high-pressure leak-proof seal is required.)

Oscar Zerk’s smaller, less expensive, more compact snap on-off ball lock design proved a worthy competitor to the more cumbersome Alemite pin-lock design.

In 1923, Oscar Zerk received his patent for the Zerk grease fitting and began marketing it through the Allyn-Zerk Co. of Cleveland, OH. His smaller, less expensive, more compact snap on-off ball lock design proved a worthy competitor to the more cumbersome Alemite pin-lock design.

So much so that, in 1924, the Alemite Co. purchased the Allyn-Zerk Co. outright and proceeded to standardize the Zerk grease fitting for the high-pressure Alemite grease-gun systems that we know (and continue to use) today.

As a testament to its original design, the grease nipple has changed little over the past century. Ask anyone to describe a manual lubrication system, and most will immediately visualize a trigger- or lever-action grease gun connected to a Zerk grease nipple. Beware, though: Not all of today’s grease fittings are the same. Successfully employing or replacing grease fittings requires some investigation.

Choose The Right Grease Nipple for Your Needs

Grease nipples are straightforward devices. Incorporating a shaped and threaded housing, ball, and retaining spring, these fittings rarely fail. Difficulty pumping grease into the nipple usually indicates a hydraulic lock situation caused by a problem with the bearing itself.

That said, grease nipples can corrode or be physically damaged when struck. Therefore, they may need to be replaced from time to time. When this is the case, a maintainer or planner should be aware of the multiple available choices.

Material Choice

The most popular and least expensive grease nipple material is mild steel. In wet, humid, and corrosive environments, choosing a nipple made from zinc-plated steel, aluminum, stainless steel, or brass may make for a better decision. Fittings made from monel are recommended in highly corrosive or caustic environments.

Thread Choice

Depending on where the machinery was made or specified, grease nipple threads may be imperial or metric. Depending on the size and application, the thread may be a straight (parallel) or taper thread, British Pipe, National Pipe, or Unified thread.

When in doubt, use a grease fitting thread gauge or a set of thread pitch gauges to determine the correct thread size. Fitting an incorrectly threaded nipple can cross-thread the bearing and cause grease leakage.

Note: for light duty applications, non-threaded drive fittings are available

Style Choice

Depending on access to the grease nipple, the fitting style may need to be considered. Most grease nipples are straight (directly lined with the bearing entrance). For poor-access areas, angled grease nipples may prove advantageous. Grease nipples can be purchased in 90-, 60-, and 45-degree angles.

Extended-barrel nipples can be purchased when reach is a problem. If protrusions of any type interfere, non-protruding or flush grease nipples can be employed.

Specialty Fittings

A large button-head fitting (sometimes called a DIN fitting) is available for heavy, high-powered machinery. This is a positive-lock design that will require its own grease-gun applicator device.

Where absolutely no leakage is allowed, the original Alemite pin-lock fitting is still available. Like the button-head fitting, though, it will require a specialized grease-gun applicator device.

An air-vent, or breather-style, grease fitting can be purchased for closed gearboxes, transmissions, etc.

Pressure-relief grease fittings relieve internal bearing pressure where continued positive internal pressure can cause problems.

Hydraulic-shut-off grease fittings are designed to restrict grease flow at a designed pressure to protect the bearing seal from rupture during the filling operation.

When manual greasing is your preferred lubrication method, choosing and using the correct grease nipple is very much a RAM (reliability, maintenance, availability) best practice.

So, don’t just think of the lowly nipple as something that’s been doing the same job the world over for 100 years: Think of this fitting as a critical, engineered choice that can ensure a bearing is always ready to receive lubricant.

Initially published in The RAM Review.

If a machine is to provide service life past its warranty stage, its designer must envision and consider all operating conditions under which it will operate in the field.

For example, to mitigate the effects of severe and semi-severe conditions, the design must be adjusted to protect bearing surfaces from contamination by water, heat, and fine particulate matter (dust, dirt, and manufacturing debris) in such environments.

The dictionary defines contamination as the presence of a constituent, impurity, or some other undesirable element that spoils, corrupts, infects, wears, or reduces the fitness of a material, physical entity, or environment.

Translation: Contamination is a machine killer. And sites that operate lubricated-equipment systems can’t afford to ignore it.

Suppose a machine has any replaceable/washable filter, screen, or breather as part of its fluid-management systems, i.e., lubrication systems, hydraulic systems, pneumatic air systems, etc. In that case, we can assume the OEM (Original Equipment Manufacturer) designer/engineer fully expects the machine and its operator/maintainers to manage associated airborne and fluid-borne contaminants.

Built-in sacrificial machine-filtration elements are designed to provide an inexpensive method of controlling potential contamination issues and protect the delicate close-tolerance machine bearing surfaces. Suppose the equipment’s reliability and availability are to be truly maximized.

Contamination control through machine design must be backed up with a maintenance/operations-contamination avoidance (CA) strategy once the unit has begun operating.

Contamination Control

When bearing surfaces interact, they rely on a sufficient supply of clean, contaminant-free lubricant to separate and protect their surfaces. Strategically placed filters in the lubrication system ensure any particles or moisture are extracted and trapped in its media before the lubricant can enter the lubricated zone(s) and cause surface damage.

Most filters for this type of contamination control incorporate a passive surface-attractant media that restricts and captures suspended contaminants (dirt or water) as a lubricant or lubricated air flows through or across it.

Depending on the working conditions, the expected contaminate particle size, and the fluid-flow rate, filter-media construction can vary from simple wire mesh gauze to, among other things, wire wool, pleated paper, cellulose, porous metal, fiberglass, diatomaceous earth, and felt.

Due to grease systems’ heavier fluid viscosity and line-delivery pressures, heavy-gauge coiled wedge wire or wire mesh filters are employed to attract large solid contaminants that may be introduced into the lines from a dirty grease gun nozzle.

Enclosed, sealed gearboxes and reservoirs require breather devices to equalize pressure and control solid and moisture contamination. Old-style breathers constructed of wire wool can only protect against large solid contaminants 40 + microns in size.

Such breathers are regularly replaced with newer styles that employ desiccant-like silica gel hydrophilic media. This media type allows reservoirs to breathe and prevent outside airborne particulates 3+ microns in size from entering the reservoir.

It also can wick and capture moisture from inside the reservoir while preventing outside moisture from entering the reservoir or gearbox chamber. Remember that severe water contamination in a gearbox or lube reservoir is best detected and drained off using integrated external sight gauges (tube and bullet style) that employ drain and sample ports.

Additional workplace contamination control methods may be required in severe environments, such as those involving substantial manufacturing-process-raw-material particulate. These methods can include:

• physical protective barriers/covers over bearing areas
• positive- or negative-pressured manufacturing areas with airlocks and HEPA (high-efficiency particulate air) filtration
• positive lock-on fill systems that require no fill caps or drains
• closed-loop expansion-tank designs that eliminate the need for breathers.

Contamination Avoidance

Once a machine is operating in the field, the maintenance and operation staff must work as a team and ensure the workplace is kept as free of contaminants as possible.

Unfortunately, although contamination avoidance is a primary strategy for reducing and eliminating premature bearing failure, it is often conspicuous in its absence from many lubrication programs.

A good contamination-avoidance program requires little to no capital outlay, fits perfectly into any PM/PdM program, involves the cooperation of operators and maintainers, and is based on common sense. Contamination avoidance ensures contaminants cannot contact a machine and its bearing-protection systems.

Effective contamination avoidance calls for a good relationship between operations and maintenance teams and a healthy respect for machines and their components. The following five points sum up the foundational elements of any contamination-avoidance initiative:

1. Good housekeeping, Order, and Cleanliness: This refers to the machine and the lubricant-storage area and transfer equipment. Ensuring that dirt doesn’t accumulate on machinery and equipment surfaces is Preventive Maintenance 101. It’s also the responsibility of operators and maintainers alike. The introduction of a simple 5S program will facilitate this element.

2. Lubrication Training: Understanding the consequences of failing to arrest contamination is mandatory. Using processes and procedures will ensure consistency of effort.
3. Lubricant Storage and Transfer Engineering: Dedicated, color-coded, and closeable storage and transfer equipment ensures lubricants are protected from the elements and cross-contamination exposure. Automated systems ensure minimum lubricant exchange/fill points.
4. Condition-Based Oil Changes: Too frequent oil/filter changes can increase exposure to contaminants; infrequent oil/filter changes can exhaust the filtration media and lead to degradation of the lubricating fluids. Condition-checking allows operators and maintainers to become more familiar with the machinery.

5. Lubricant Cleanliness: This element means testing all new lubricants and bulk fluids to determine fluid cleanliness and additive-package formulation before use and verify the products have been delivered in a clean-state specification.

Of course, every operation is unique and will require a tailored contamination control/avoidance strategy. However, This type of strategy is arguably the simplest, least expensive, and most effective reliability program a company can implement. As I’ve often said and written, now is the time to update yours. Why are you waiting?

Originally published in The RAM Review

Lubricants encounter negative influences throughout their working life, including load-induced shear stress, thermal degradation, water contamination, aeration, wear metal catalyzing, and contamination from dirt, chemicals, and incompatible lubricants and fluids.

These external influences can produce an array of fluid property-altering effects that manifest as oxidation, polymerization, cracking hydrolysis, and fluid evaporation, which can lead to a major thickening or dilution in viscosity, acid buildup and reservoir sludge.

Lubricating oils consist of base oil and an engineered, consumable additive package designed for the oil’s intended service, such as gear oil, automotive engine oil, and air-tool oil. The additive’s function is to combat and stave off the effects of outside influences and deliver a reasonable oil life cycle, whatever ambient conditions prevail.

What About OEM Oil Change Interval Recommendations?

Because OEMs (original equipment manufacturers) have little or no control over the actual working and ambient conditions in which their systems operate, they make oil-change recommendations based on ideal conditions and a 40-hr. operating week.

Following only OEM recommendations could mean changing your oil too early or too late for your particular conditions.

That could translate as additional costs for meaningless oil changes or repairs. Thus, the only way to set an oil-change schedule is to regularly test and trend the lubricant to determine when and how it degrades.

Doing so can help an organization establish a fiscally responsible, condition-based approach toward oil-life-cycle management.

When determining an oil’s condition and remaining life expectancy, we must analyze its fluid properties to establish the presence of an additive package, its depletion rate, and its oxidization presence/effect.

To verify if and when an oil change is warranted, the lubricant is tested in numerous ways against a virgin oil baseline with two primary measured indicators leading the decision-making process:

1. Major changes (up or down) in an oil’s viscosity measure.

2. Increase in an oil’s acidity AN (Acid Number) measure.

Viscosity Testing

When looking at the Viscosity rating of new oil, typically, the viscosity is measured in Centistokes (cSt), the oil’s Kinematic Viscosity rating that depicts its measured resistance to flow and shear caused by the force of gravity.

As the oil thickens or dilutes over time, its specific gravity (SG) changes and can result in testing errors when using a gravity-based viscosity test.

A more consistent measurement is achieved by measuring its internal friction by checking for the Absolute Viscosity rating that depicts the oil’s resistance to flow and shear.

Since absolute viscosity is determined by multiplying kinematic viscosity by the actual specific gravity, it delivers an accurate and error-free trending measurement, making it the preferred choice for most oil labs. You will know the difference between the two viscosity scales, as absolute viscosity is measured in centipoise (cPs) instead of centistokes (cSt).

Due to the large variables encountered in oil use, working with a laboratory with experience setting up caution and critical limits for your industry type is preferred.

Typically most labs will start with a clearly defined set of viscosity working limits of -10% CL (Critical Lower), -5% CaL (Caution Lower), +5% CaU (Caution Upper), and +10% CU (Critical Upper) for Industrial oils. In more severe environments, the CaU and CU limits can be reduced to +4% and +8%, respectively. For oils with Viscosity Improvers, the lower limits are usually doubled.

Acidity Testing

The AN (Acid Number) measures the acid concentration in the oil—not the acid strength—and is greatly affected by the presence of water within the oil. Most virgin oil starts with an acid number less than 2.

Setting limits for oil acidity is not as easy as for viscosity, as caution and critical limits are set according to the type of additive package used in the oil. Most standard mineral oils are considered corrosive if measured above AN 4, whereas AW (Anti-Wear) or R & O (Rust and Oxidation) inhibited oils are considered critical well below AN 3.

Working with your oil supplier’s engineering department and a reputable oil lab with experience in your industry is the best way to set up meaningful, acceptable limits for your environment.

As in any trending analysis, the rate of change is arguably more important than the actual change number as it signifies a specific change event that has taken place that likely requires immediate investigation.

Originally published in The RAM Review.

It’s very much a lubrication issue. To prevent two metal surfaces from welding due to excess friction, keep them apart when expected to interact. A suitable film of lubricating oil accomplishes that.

Some 50 years ago, MIT Mechanical Engineering Professor Emeritus Ernest Rabinowicz was experimenting on the tribological effects of metal-to-metal surface interaction. In his research, Dr. Rabionwicz discovered that 70% of bearings lost their usefulness due to (avoidable) surface degradation, 20% due to corrosion, and a whopping 50% due to mechanical wear.

In calculating the situation, Rabinowicz determined that 6% of the U.S. GDP (Gross Domestic Product) was lost every year through mechanical wear. In today’s terms, that equates to trillions of dollars lost to avoidable wear. We now refer to this equation/finding as “The Rabinowicz Law.”

Simply put, surface degradation can be directly and indirectly attributed to ineffective lubrication practices.

These include under- and over-application of lubricant, use of mixed lubricants, incorrect lubricant choice (viscosity and additive package), particle and moisture contamination, and neglect.

Adopting a 5R Lubrication Approach by applying the Right lubricant, in the right place, in the Right amount, at the right time, with the Right level of cleanliness, surface degradation can be minimized to acceptable and often negligible levels.

Once established, the level of lubrication protection is dependent on the lubricant film, the thickness of which affects and controls the degree of interacting surface degradation and resulting wear. These varying thickness states are called lubricant film regimes.

Lubricant Film Regimes

There are five lubricant film regimes. Each describes a different relationship between two interacting surfaces as they slide over one another.

HDL—Hydrodynamic Lubrication is often described as “Full Film” lubrication, in which the moving surfaces are completely separated by the lubricant.

Viewing bearing surfaces under a microscope reveals that even finely machined surfaces are anything but flat. They’re more likely to resemble a series of craggy, rubbed-down peaks and valleys.

A lubricant must first fill those cavities to separate and ensure optimal interaction between two moving metal surfaces. In sliding friction bearings, HDL is the most desirable lubrication state. It’s often referred to as thick-film lubrication, wherein any friction is entirely due to the fluid friction between the viscous planes shearing in the lubricant.

EHDL—Elastohydrodynamic Lubrication is unique to rolling-friction surfaces seen in ball—and roller-style bearings and in combination with sliding- and rolling-friction circumstances found in the mating of gear teeth as they pass over one another.

When a ball is rolling in a race and comes under full load, the mating surfaces will momentarily deform, trapping the lubricant in the deformed area known as the Hertzian contact area. Under deformation pressure, lubricant viscosity rapidly rises, and the lubricant changes state from a liquid to a solid, thus providing complete protection to the rolling surfaces.

The lubricant returns to its original viscosity as the ball moves out of the load zone. Because rolling-surface contact is in a line and not over an entire surface area, far less lubricant is required to achieve full-film lubrication. Viewing a vehicle’s tire in motion can easily demonstrate this action.

A properly inflated tire always appears round except for the deformed or flattened portion, taking the load and providing traction with the ground. As the tire rotates, it elastically comes back to its rounded form.

MF – Mixed Film Lubrication is classified as an Intermediate lubrication regime when lubricant is present between two sliding surfaces but not enough to fully separate the surface, allowing intermittent contact between the highest points of the surface peaks. This is known as an “unstable” regime.

Extended time spent in this regime will result in the surface high points shearing off and, in turn, create additional cutting wear to the bearing surface due to asperities rubbing both surfaces. MF conditions are generally caused by insufficient lubricant, heavy loads at rest, or using a lubricant with too low viscosity.

In the 1800s, steam engines were designed with large-diameter Babbit (very soft material) crankshaft bearings. These bearings were lubricated with two different manual-oil-lubrication-delivery systems used in sequence.

The first was a manual pressure pump used to hand-pump oil into the bearing cavity and hydraulically float the bearing before startup. Once running with the shaft at a steady 70- to 100-rpm working speed, lubrication delivery was switched to a gravity-feed oiler that ensured continuous flow into the bearing to achieve full-film lubrication.

This two-part process moved a bearing’s lubrication state from HSL to HDL while minimizing/eliminating the problematic effects of MF and BL (see below) lubrication states.

BL – Boundary Layer Lubrication, or thin-film lubrication, is the least desirable regime offering the least frictional protection. Although minimal lubricant is present, the sliding surfaces are in full contact with one another at rest. With heavy loads and slow-moving machinery, a BL to MF regime may be the best condition achievable. This situation, though, requires a lubricant with EP (Extreme Pressure) and AW (Anti Wear) additives to offset the extreme bearing-surface working condition.

If insufficient lubricant or an incorrect viscosity is used, a normally loaded bearing can stay in a boundary-layer state when in full motion. In that case, the surfaces will interfere and cause rapid wear.

In 1902, Professor Richard Stribeck graphically described the coefficient of friction changes for bearings under different lubrication regimes. His work resulted in what we know as the Stribeck Curve (see figure). The Stribeck Curve demonstrates that hydrodynamic film regimes of the correct viscosity and Lambda thickness lead to the lowest coefficient of friction and least wear.

The Stribeck Curve describes the coefficient of friction changes for bearings experiencing different lubrication regimes.

A typical example of Stribeck’s findings is found in normally loaded sliding friction bearings, such as those in a shaft and sleeve bearing setup. At rest, the bearing surfaces will begin in a boundary-layer or mixed-film state before startup or shutdown.

As the shaft ramps up speed, it will start to centrifugally center and move through a mixed film regime to a full film HDL regime at operating speed. Load, speed, and lubricant viscosity changes can also affect the regime state.

Full-film lubrication has a typical thickness between 1 and 5 microns. To put that into perspective, consider that bacteria are 2 microns in size; a red blood cell is 8 microns; a human hair is 75 microns or 0.003 of an inch. In contrast, silt or dirt comes in at around 5 microns (possibly larger), which could easily create wear surface damage if allowed into the bearing surface area.

Humans only begin to see objects at 40 microns in size. Therefore, we must be diligent in understanding and ensuring that the 5 Rights of Lubrication are always followed. Doing so will ensure a bearing operates in its designed lubrication regime, avoids unnecessary wear, and lives a long life. In the end, a bearing’s fate is always in the hands of the maintenance department.

First published in The RAM Review

In the most basic of terms, an electric motor is a simple device that converts electrical energy into rotary motion that, when transmitted to a driven load, will perform mechanical work. If applied correctly, the motor will run effortlessly. If set up correctly, the motor will perform reliably at minimal cost.

The motor will have a long service life if maintained regularly and correctly. This is so much so that, for most motors, only 2% of their total lifetime cost will be attributed to the original purchase price, with the remainder to energy costs.

Although the world is witnessing a renaissance of the electric motor with the advent and continued proliferation of e–motor vehicles, their fundamental design and purpose remain the same. Similarly, application, setup, and maintenance will continue to influence the performance, reliability, and life cycle of the e-motor.

Application, setup, and regular maintenance are all cornerstone elements of precision maintenance, providing a simple, effective, and straightforward approach to ensuring your motors work efficiently for a long time.

Application

A new machine pretty much guarantees the motor has been sized correctly to its intended load. Application problems arise when the maintenance department changes a defective or failed motor with one that’s not “like for like.” Motor application mismatching can also occur when the production team modifies operating conditions by:

• Changing the line or machine speed beyond its original design range.
• Changing the raw material that’s being worked.
• The machine was re-purposed for a different use than the one for which it was initially designed.

An oversized motor for the load condition can provide adequate performance. Still, light loading will often be inefficient and consume excess energy under regular operation, increasing the unit’s energy footprint.

Conversely, an undersized or too-light motor will, at best, stall or trip under load, may fail to operate, and could cause motor damage. In a worst-case scenario, the motor continues to run and overheats, causing a fire.

In particular, in applications when a heavy startup load is expected to reduce significantly once the equipment is running at operational speed, i.e., in a loaded conveyor drive system, there are two options: We can use reduced-horsepower motors that 1) are governed mechanically by a fluid coupling that allows the drive to come up to speed slowly without tripping the motor; or 2) are governed electrically through use of a Variable Frequency Drive (VFD).

If a motor size is suspect, ensuring the unit is sized correctly requires reviewing the original manufacturer’s literature (design specification, Bill of Material, spare parts list, etc.). If no literature is available and you are unsure if the replacement motor is the same size as the original unit or if you wish to change to a high-efficiency model, confer with your local motor supplier’s engineering department for assistance.

Setup: Balancing

Purchasing a new, reputable, name-brand electric motor should provide some assurance that the unit’s main shaft is balanced. When it comes to new, inexpensive, offshore “no-name” motors, operations should err on caution and have the balance checked and certified by a reputable motor shop. Rebuilt motors should have a balance certificate if purchased from a reputable rebuilder.

Unbalanced motor shafts are noisier, vibrate more than usual, require significantly more energy (and money) to operate over time, and often fail prematurely.

Always check a new or rebuilt motor’s balance using your vibration-analyzing equipment, or have it certified independently by a reputable local motor shop, and do so before you place the unit in operational use.

Setup: Alignment

The correct alignment between the drive and driven shaft is arguably the most essential part of any motor setup.

Misalignment comes in two forms: 1) Angular, in which the shafts line up center-to-center but not in a straight line, and 2) Offset, in which the shafts do not line up center-to-center. Both conditions can occur simultaneously. Both will place tremendous stress on the driver and driven bearings and couplings, assuring rapid wear, premature failure, and a considerable increase in motor energy consumption.

Remember: Poor alignment will rapidly wear out shaft bearings, sprockets and chains, belts, and sheave pulleys.

Setup: Soft-Foot Check

A soft-foot condition check should always be included in the alignment process. Aligning with a laser-type alignment system is easy, as virtually all laser alignment systems feature a soft-foot check feature.

Soft foot occurs when one or more motor base feet are not as flat as the others (think of a table with a short leg). Soft foot can also occur when the motor base grout is not flat or square. Both situations are easily remedied with precision shims and correct tie-down-bolt torquing.

If the soft foot persists, excess vibration will eventually loosen the bolts and cause the motor to vibrate more, which will transfer across the drive train and its components. Again, the result will be premature wear and failure, combined with excessive energy consumption.

Regular Maintenance: Lubrication

The reality is that most electric motors are grossly overlubricated. Incorrectly lubricated motors prematurely fail due to the simple act of neglecting to undo the grease drain plug.

This forces any excess grease to build up pressure that eventually ruptures the shaft seal. In that event, grease is free to purge into the motor winding, causing massive overheating, premature failure, and, once again, excessive energy consumption.

Some sub-fractional motors come equipped with grease nipples, even though they contain lifetime lubricated bearings and no drain port to allow excess grease entry to escape.

All motors should be assessed to understand their lubrication requirements and placed on an engineered lubrication program.

Regular Maintenance: Cleanliness

The simple act of keeping a motor dirt—and oil-free will combat the buildup of a debris/dirt-based thermal blanket, allowing the unit to cool as designed and, just as important, use no more energy than designed.

Regular Maintenance: Maintaining the Driven System

Simple maintenance of the driven systems can significantly reduce motor loads and increase energy use efficiency. Among other things:

• Ensure drive belts and chains are tensioned regularly and correctly.
• Use matched drive belts on multiple belt systems.
• Always replace sprockets while the worn chains are being replaced.
• Lubricate drive chains regularly.
• If the motor is coupled to a gearbox, ensure the lubricant has the correct viscosity.
• Ensure the driven component is balanced and lubricated regularly.
• When aligning with direct coupling, use the least-expensive non-flex style that’s required and enforce accurate alignment techniques.
• Check driven-system air filters or fluid-system filters regularly.

What’s the payback from following the steps described here? Remember: With a precision-maintenance approach, an electric motor will virtually always outlast its driven system.

First published in The RAM Review

Safety in the workplace is paramount. Few people would disagree with this statement, especially working professionals in the maintenance and lubrication fields, who are primarily well-trained in this area.

When it comes to handling and transferring chemicals and lubricants, the safety dress code for personnel must be specific and very clear. The need for the correct personal protective equipment (PPE) is absolute.

Typical PPE will, at a minimum, include protective footwear, coveralls, gloves, and eyewear designed to protect against skin and eye contact exposure to oils, greases, and chemicals for anyone handling, transferring, or cleaning up spills.

Here’s A Tip: As each plant or workplace supports using a unique inventory of lubrication fluids and chemicals, determining the correct PPE requires maintenance to list all lubricants and chemicals on site.

This list is then used to gather an up-to-date set of Safety Data Sheets (SDSs) for each lubricating fluid and chemical used in the plant/workplace from the lubricating fluid supplier(s). Once this has been done, these documents can be referenced to build a specific PPE-requirement table listing for each fluid, based on what’s spelled out in “Section 8: Exposure Control/Personal Protection” of its SDS.

Based on this table, a standardized corporate or departmental set of PPE for lubricating fluid handling and transfer requirements can be developed. Note: Fluids that require additional non-standard PPE (e.g., use of a respirator for lubricants, chemicals, and solvents identified as potentially hazardous to lungs) are best identified and listed as an additional PPE requirement on the work order.

At this point, the PPE lists and SDS library have become an asset, which, like any other asset, must be maintained to remain current and effective.

Keep in mind that lubricating fluids are heavy. With a standard 55-gal. drum weighing close to 500 lbs., proper training on the correct use of lifting devices, slings, and ergonomic devices is essential.

In addition, to protect against accidentally dropped or tipped lubricating fluid containers, all boots and shoes should be grade-one safety certified with steel toes and puncture-proof, oil-resistant soles.

Thus far, this article has focused on the common hazards associated with storing, handling, and transferring lubricating fluids into machine reservoirs.

However, once those fluids are in a pressurized lubrication-delivery system, such as an automatic grease or oil lubrication system, hydraulic system, or a simple manual pressurized grease gun, a whole new set of potential hazards confront the maintainer, lubrication technician, or machine operator. Referred to as “high-pressure injection hazards,” they can be lethal.

Lube-Application Safety Specifics

Most people are unaware that simple electric/compressed air grease guns available from local hardware and big-box stores can deliver lubricants at nozzle pressures up to and greater than 5000 psi. Nor do they realize that an innocuous hand grease gun can develop pressures up to 15,000 psi.

A 2020 study titled, Management of High-Pressure Injection Injury of the Hand in the Emergency Department, by S.O. Sanford and T.J. Mills (see link below) noted that “High-pressure-injection injuries occur when a high-pressure injection device, such as a paint or grease gun, injects materials into the operator [skin].

This injury most commonly occurs in the dominant hand and index finger.” As the researchers further explained, “The injection typically occurs to the fingertip when the operator is trying to wipe clear a blocked nozzle, or to the palm when the operator is attempting to steady the gun with a free hand during the testing or operation of the [grease gun] equipment.”

Similar injuries can occur when performing condition and leak checks on other pressurized hoses and lines (especially flexible-line material). Alas, it’s not uncommon to see maintainers and machine operators in TPM (Total Productive Maintenance) environments running their hands over high-pressure flexible lines to feel for leaks or soft spots that, if found, can easily inject fluid into a curious hand. Leak checks are best performed using a piece of stiff card, NEVER your arm, hand, or fingers.

Proper grease-gun training instructs the operator never to place his or her finger directly over the flexible delivery tube or nozzle tip when activating the trigger.

When cleaning the nozzle tip, always take the non-dominant hand off the trigger or pump lever. Unfortunately, many companies fail to provide adequate grease gun training to maintainers and machine operators.

Injection through the skin can occur at less than 1,000 psi. The higher the pressure, though, the more damage that can occur to the structure of the hand or finger. (If you ever received an inoculation in your arm using a medical pressurized jet injector, you may recall that the “pressure” felt pretty low, as such devices operated between 1,000 and 2,000 psi. Imagine, however, what pressures of 5,000 psi to 15,000 psi could feel like or do to a body part.)

It could be easy to ignore a pressure-injection injury and, ultimately, begin second-guessing if it did or did not occur. Don’t. According to the cited Sanford and Mills study, “A high-pressure injection injury should be considered a surgical emergency.”

To learn why, refer to the 2018 YouTube safety video titled Hydraulic Injection from Northwest Linemen College. It visually demonstrates how, if it’s not quickly addressed medically, a seemingly small injection site, with a slight area of redness, can turn into a devastating injury within mere hours.

The Sanford and Mills study found the overall incidence of amputation stemming from pressure-injection hazards was 48%. Solvents caused the greatest damage, followed by grease injection. In 25% of all cases, amputation occurred.

Similarly, in an earlier medical study performed at New York Methodist Hospital, J.T. Snarski, and R.H. Birkhan found that high-pressure grease guns/systems were responsible for 57% of all injection injuries, seconded by hydraulic-fluid injuries. Furthermore, the researchers found that the overall incidence of medical amputation resulting from such injuries was 48% and closer to 100% when injection pressure was greater than 7,000 psi.

Even if affected limbs can be saved, the long-term outcomes for the injured individuals are not always good. For example, the Sanford and Mills study found that among those who underwent successful surgical debridement, 50% ended up with a reduced range of motion; injuries adversely affected daily living activities; grip strength was reduced by 35% in 75% of cases; and all patients continued to suffer from some level of neuropathic pain.

Knowing What to Do

If you suspect a high-pressure injury has occurred, you (or the person in question) must seek professional medical treatment immediately. Studies show that the quicker these injuries are recognized and professionally treated, the higher the chance of limiting damage and saving an affected limb.

The Sanford and Mills study listed the following details that physicians require to determine the severity (and treatment) of pressure-injection injuries:

• Type and viscosity of the injected material (a copy of the fluid-type SDS is essential here).
• Time interval between injury and treatment (log when the injury occurred).
• Amount of material injected and velocity of injectant.
• Pressure of the appliance (or system).
• Anatomy and distensibility (swelling amount) of the site of injection.

If possible, use a smartphone, tablet, or other device to photograph or record a video of the injury as soon after the incident as possible. Also, photograph or record a video of the injection device.

In its safety video, Northwest Lineman College recommends the following first-response plan for pressure-injection-type injuries:

• Treat Immediately (seek medical attention).
• Don’t let the victim drive.
• Don’t leave the victim alone.
• No food or drink.
• Immobilize and elevate the wound.

If you feel that you (or others) have ingested lubrication fluid, have skin or eye irritations through exposure, or believe you (or someone else) may have suffered a pressure-injection injury, seek medical advice immediately. Since time is of the essence in these situations, it is always better to be safe than sorry.

First published in The RAM Review.

Grease guns seem simple enough. But how well do you know yours? Do you know how to correctly cartridge and bulk load your gun? Do you know how to expel trapped air from it? Do you know its shot size in cc or cu in (e.g., in cubic centimeters or cubic inches)?

Do you know how much pressure your gun can develop? If you don’t, you’re not alone.

In reality, many grease-gun operators have never been adequately trained to correctly fill a grease gun or determine its output or pressure.

Since most of these devices are now being manufactured offshore, they rarely come with specification sheets or quality instructions. Let’s examine some best-practice user fundamentals associated with these lubrication workhorses.

Grease-Cartridge Loading

Most of the grease guns that are purchased these days use grease cartridges. To load a new cartridge correctly:

1. Wipe the grease gun clean with a lint-free rag.
2. Unscrew the grease gun head from the barrel and place it on a clean surface or paper towel.
3. Firmly hold the grease barrel in one hand and pull back the rod handle at the end of the barrel with the other hand until it can go no further and lock into position. NOTE: Depending on the rod style, it may have a friction-lever lock built into the end of the barrel that automatically holds the rod in place when extended. Or, the barrel end may have a slotted hole that requires the extended rod to be positioned across the slot into the locked position.
4. Carefully remove the spent cartridge from the open end of the barrel, taking care not to cut a finger with the sharp open edge of the spent cartridge.
5. Place the barrel next to the head on a clean surface.
6. Ensure the new grease cartridge is filled with the same grease as the old cartridge. If not, the grease gun must be thoroughly degreased and cleaned to ensure bearings are not cross-contaminated with two different greases.
7. Pull the plastic end cap off the grease cartridge and insert the cartridge into the grease-gun barrel open end first. Once fully inserted, remove the pull-tab foil end from the cartridge.
8. Fully screw the grease gun head back on the barrel and back off (loosen) one turn.
9. Release the rod handle by pushing the friction-lock lever or returning the lever rod back across the slot to its center position, then slowly push the rod back in place in the barrel as far as it will go.
10. Pull the trigger or pull/push the lever until grease begins to dispense, then securely tighten the gun head.
11. If no grease flows, an airlock is likely to blame. To release trapped air, pump the grease gun a couple of times, then, if fitted on the grease head, push the air-release valve and re-pump the grease gun. If grease still doesn’t appear, repeat the process. On smaller grease guns with no air-release valves, back off (loosen) the barrel a couple of turns, and pump until grease appears, then retighten the barrel,
12. Wipe the grease gun with a lint-free cloth, then place all spent materials in a contaminated waste container for removal.

Bulk-Loading Grease

Some grease guns have a dual-fill feature, whereby the barrel can accommodate a standard grease cartridge or be bulk-loaded. For such guns and those designed specifically for bulk loading:

1. Wipe the grease gun clean with a lint-free rag,
2. Unscrew the grease-gun head from the barrel and place it on a clean surface or paper towel.
3. Immerse the open end of the grease barrel into the bulk-grease container and slowly plunge it into the grease while drawing back the rod handle until it is fully extended and the grease barrel is full.
4. Alternatively, the barrel can be hand-packed from the open end with the rod extended and locked. NOTE: This fill type can be messy and prone to dirt and air inclusion.
5. Fully screw the grease-gun head back on the barrel and back off (loosen) one turn.
6. Release the rod handle by pushing the friction-lock lever or returning the lever rod back across the slot to its center position, then push the rod back in place in the barrel as far as it will go.
7. Pull the trigger or push/pull the lever until grease begins to dispense, then securely tighten the gun head.
8. If no grease flows, an airlock is likely to blame. To release trapped air, pump the grease gun a couple of times, then, if fitted on the grease head, push the air-release valve and re-pump the grease gun. If grease still doesn’t appear, repeat the process. On smaller grease guns with no air-release valves, back off (loosen) the barrel a couple of turns, pump until grease appears, and then securely retighten the barrel.
9. Wipe the grease gun with a lint-free cloth, then place all spent materials in a contaminated waste container for removal.

Output and Delivery Matters

A grease gun is a simple design based on basic hydraulic pump principles. Depending on your device’s internal design, a few strokes of the trigger or lever can produce an astounding delivery pressure (ranging from 2500 to 15,000 psi).

With that type of output pressure and lack of grease-delivery knowledge and discipline, it can be easy for an untrained grease gun operator to destroy bearing seals and over-lubricate bearings, which, in turn, can result in premature bearing failure and downtime.

Sadly, grease-gun output pressure is rarely stamped on these devices. A simple pressure-test rig can be constructed using a fixed 20,000-psi hydraulic gauge connected to a grease fitting. Connect the grease pump to the fitting and perform a “dead head” pump to see and record the generated pressure.

To measure the grease-pump-delivery output, purchase a test tube marked in cubic centimeters or cubic inches and pump in 10 shots of grease (One complete lever or trigger cycle equals one shot). Divide the total amount shown in the test tube by 10 to arrive at the actual shot size.

For example, if the test tube showed 27 centimeters of grease, the actual shot size would be 27/10 = 2.7 cc. (Pneumatic- and battery-operated grease-gun shot size can be calibrated the same way or by hooking these types of devices up to a flow-metering device.)

Note: Grease guns aren’t all built to the same design specifications. Therefore, their displacement-output volumes, or “shot” sizes, will likely differ. This poses enormous problems for a plant when a PM task calls for two shots of grease and the guns used at the site haven’t been standardized.

Remember that two shots of a 3-cc-displacement gun will deliver six times more lubricant than two shots of a 1/2- cc-displacement gun.

Some grease-gun manufacturers confuse the delivery-output issue by marketing grease-gun-reservoir capacities and “shot” displacement by weight (in grams and/or ounces).

On the other hand, grease manufacturers use different ingredients and formulations for each grease type, resulting in different specific gravity ratings and weights. This means that similar volumes of grease can have different weights.

For example, greases can be marketed in a standard grease-gun cartridge with the same volume, but one cartridge might weigh 300 grams while another weighs 400 grams. Bearing-fill cavities are measured in volume, not weight. Therefore, always use volume displacement as your grease unit of measure.

Finally, once a grease gun’s pressure and shot size are known, it’s essential to print out a tag with that information and attach it to the gun.

Cleaning and Storage Practices

After a grease gun has been used, it should be cleaned and made ready for its next assignment. Be sure to store it vertically in a grease caddy. These types of caddies can be magnetized to your toolbox or metal cupboard or screwed to a wall.

This type of vertical storage will ensure your lubrication workhorse remains free of damage, dirt, and, importantly, cross-contamination from other grease guns.