Respect the Cornerstones of Manual Grease Lubrication

Lubrication • Lubrication Management & Technology

Respect the Cornerstones of Manual Grease Lubrication

Ken Bannister | May 16, 2016

One hundred years ago, the grease-gun innovations of Oscar Zerk and Alemite’s Arthur Gulborg forever changed the way machines were lubricated. Today, those combined technologies continue to reflect the most popular method of lubricant application in the world.

Effective manual greasing technologies and practices remain crucial to equipment health in countless plants.

The early 20th century proved to be a truly innovative era for machine life-cycle management, thanks, in part, to two competing inventions. Collectively, they forever changed the way machines were lubricated. The idea was so simple and effective that even now, as we celebrate the 100th anniversary of the technology’s launch, it continues to be the most popular method of lubricant application in the world.

A short history lesson

The year was 1916; the place was Chicago. Tasked with the time-consuming, repetitive refilling of grease cups on die-cast machines in his family’s business, Arthur Gulborg was motivated to develop a less-taxing lubrication process. He achieved his goal through a portable grease-cup design that incorporated a large cylindrical-shaped reservoir with a screw-style end-cap (similar to the original grease cups) and a proprietary opposite-end fitting that mated to a bearing-point fitting made from a braided metal hose.

Gulborg called his invention the “Alemite High-Pressure Lubricating System” (based on the name of the family business). Initially pitched to the military for lubricating transport trucks, the Alemite system received a large boost in sales with the introduction of a “button-head” style grease fitting, which was later adopted as standard equipment on passenger cars in the early 1920s.

As Gulborg was beginning to enjoy success with his portable manual-greasing system, over in Cleveland, OH, Oscar Zerk was busy inventing one that incorporated a compact nipple- or ball-shaped grease connector. That uniquely shaped component let the specially designed grease-gun coupler “snap” onto the connector, allowing high-pressure grease transfer between the gun and fitting without the need to “push” hold the coupler in place as in Zerk’s earlier designs. This innovation, appropriately, became known as a zerk fitting. When Alemite acquired the Allyn-Zerk Co., in 1924, it combined its own updated lever-action grease-gun technology with the popular compact grease nipple and coupler design. The two technologies have remained faithful to their original design to this day. (Alemite is now a business of SKF, Stockholm and Kulpsville, PA.)

Paradoxically, the inexpensive, robust, and relatively straightforward design of these manual-greasing solutions has, over the years, lulled many technicians into the belief that they are holding a “connect and pump” system that requires little or no training or understanding to operate effectively. On the contrary: Manual greasing requires an “engineered” and disciplined approach if it is to effectively extend bearing life. In untrained hands, a grease gun is a liability that will produce a negative effect on bearing life.

Ensuring best practices

Successful manual-greasing programs are built on four simple cornerstones:

Cornerstone #1: Consolidation. At any one time, a typical plant with no lubrication-management program in place could have dozens of standard and specialty greases on hand and available for use. If an exact grease specification is not identified on the work order, the grease gun, or the bearing point to be lubricated, the chances of cross contamination through use of two—or more—greases in the same bearing are high.

All greases are not created equal. Many are incompatible with each other. Grease also has a shelf life, and old product is not recommended for use in bearings. All greases present serious problems for machinery when incompatible and old and new products are introduced to each other in bearing cavities.

Combating this problem requires a simple lubricant-consolidation study designed to minimize the number of grease lubricants used in a plant. Often, specific greases end up in the plant inventory based on a manufacturer’s recommendation—some from many years past! Many of today’s high-quality lithium greases are able to perform a much better job than older designed—and often more expensive—greases. A lubricant supplier’s technical group can perform a survey on your behalf to inventory your bearing needs, your current stock, and its age. The survey should result in recommendations for the minimum number of greases actually required in your plant. The reduction can be dramatic, and will not only save money due to reduced inventory requirements, but also will simplify lubricant identification and help eliminate cross-contamination problems.

Cornerstone #2: Standardization. We standardize the greases we use through lubricant consolidation. Next, we must standardize the grease guns we use for application.

As with grease, all grease guns are not created equal or built to the same design specifications. The biggest issue involves their displacement output volume, or “shot” size. This poses huge problems when a preventive-maintenance (PM) task calls for two shots of grease and the site’s grease guns aren’t standardized. For example, two shots of a 3-cc displacement gun will deliver six times more lubricant than two shots of a 0.5-cc displacement gun. Over-lubricated bearings create internal fluid friction that leads to overheating and premature bearing failure. If the volumetric displacement cannot be found on the gun or in the accompanying literature, displace 10 shots of grease into a test tube, measure, and divide the results by 10 to assess the correct shot size and clearly stamp or indelibly mark that shot size in cubic centimeters or cubic inches on the side of the grease-gun barrel.

To facilitate the change-management process, allow maintenance personnel to take home and keep old, used grease guns. Replace all old guns with new, identical-specification models. The new devices can be either cartridge or bulk-fill in style, as long as only one style and shot-displacement size is used.

Cornerstone #3: Cleanliness. Bearings are precision devices manufactured in laboratory white rooms. They are not dirt tolerant! Solids contamination is an enormous problem for many plants and their bearings, which will perform poorly and fail prematurely if not protected from dirt. Ironically, in performing manual lubrication, maintenance-department practices are often a prime means of introducing dirty grease into lubricated systems, through nipples or guns.

The reality is most grease-gun operators don’t wipe the grease-gun coupling and grease nipple clean with a lint-free cloth, before and after greasing each lubrication point. The cross-contamination and over-lubricated components that result from this irresponsible behavior can lead to equipment and process failures—including catastrophic ones.

Cornerstone #4: Restraint. Because grease guns are hydraulic devices, they are capable of achieving output pressures to 15,000 psi. Alas, given the fact most bearing seals are rated at less than 500 psi, many are ruptured in the greasing process. Such ruptures result in over-lubricated, over-heated, and contaminated bearings that fail prematurely and lead to significant downtime.

Greasing should be performed with little or no weight behind the gun. Restraint is advised as soon as the technician feels backpressure in the handle of the device. This sensation (the feeling of backpressure) usually indicates a full or close–to-full cavity and that the bearing seal will likely be compromised on the next stroke.

Note that output pressure is rarely printed or stamped on grease guns. To determine that pressure, you’ll need to check accompanying literature or contact the manufacturer. Keep in mind that this step typically will not be necessary at a site where all grease guns are standardized and technicians only displace the engineered amount of shots into bearings. A small engineering study, however, is required to determine the number of shots needed for each bearing. This is calculated with the known—post-grease-gun standardization—displacement amount per shot.

Remember to always indicate the required numbers of shots and grease type on lubrication PM work orders and schedule accordingly. Unfortunately, many grease-gun operators are guilty of killing bearings with kindness by ignoring the shot amount on the work order and adding a few additional pumps “for good measure.” To be clear, discipline and restraint are mandatory in this matter: Never forget that over-lubrication is arguably responsible for most premature bearing failures.