Tips For Greasing Agricultural Equipment

Farm equipment and machinery, especially tractors, have a multitude of internal and external factors to contend with in order to operate smoothly and efficiently. Not only do tractors have many metal-on-metal joints, bearings and oscillation points, but they also operate at a wide range of temperatures in a variety of ever-changing environmental conditions. In order to combat these factors and successfully prevent premature wear, corrosion and total machine or part failure, tractors require the use of heavy-duty grease lubricants to properly protect the entire system.

But what is a grease lubricant? As defined by the American Society for Testing and Materials, a lubricating grease is "a solid to semifluid product of dispersion of a thickening agent in liquid lubricant. Other ingredients imparting special properties may be included." In essence, grease is a specially formulated thickened liquid or solid used to coat and protect different components in a machine from the harsh effects experienced during run times. In this article, we'll take a closer look at grease grading and testing, different types of grease to consider, identification of tractor grease points, and the frequency at which you should lubricate your components. All of these factors combined can be used to help set up a quality preventative maintenance program.

Grading, Testing and Types
Grease is graded and rated on a scale established by the National Lubrication Grease Institute (NLGI) and standardized by the American Society for Testing and Materials (ASTM).

The grease's consistency is determined through a simple test. This test involves dropping a cone into a cup of grease at 77F, measuring the penetration depth in 1/10mm after five seconds. The greater the penetration, the softer the grease. This degree of softness directly correlates to a specific grade ranking on the NLGI numbering system.

There are nine different grease grades on the NLGI scale - 000, 00, 0, 1, 2, 3, 4, 5, and 6. 000 is the softest grade and is fluid at room temperature. These greases are typically used in centralized systems, especially those used in colder temperatures. 6 is a relatively hard block grease, which was used in application such as old paper mills. Most greases on the market today tend to fall in the middle of the scale - grades 1, 2, and 3, with grade 2 being the most common.

ASTM test methods determine:

  • Performance of extreme pressure additives
  • Temperature at which the grease changes from a semi-solid state to a liquid state
  • Resistance to water washout
  • Tendency to separate at elevated temperatures
  • Corrosion and wear prevention

Greases typically fall within two categories - those with soap thickeners and those with non-soap thickeners. The most popular of these two groups are the greases using soap thickeners. In fact, nearly 90% of all greases available on the market fall into this category.

To properly create a grease, manufacturers must design a formulation that masterfully combines oil, thickener and additives. Typical formulation percentages generally range around a combination of 80% to 95% oil, 2% to 20% soap thickener and 0 to 15% additives. Thickeners most commonly used include:

  • Calcium
  • Sodium
  • Barium
  • Lithium
  • Lithium complex
  • Calcium complex
  • Aluminum complex
  • Clay
  • Polyurea
  • Calcium Sulfonate

Additives also improve the performance of a grease under a variety of conditions. Common additives include antioxidants, anti-wear agents, rust inhibitors and corrosion inhibitors.

Another important factor in the performance of a grease is the base oil and its viscosity. Types of base oils include:

  • Mineral oils - paraffinic and naphthenic
  • Synthetic - PAO, PAG, ester and alkylbenzenes
  • Bio-Based - vegetable
  • Other - silicones and fluorinated fluids

With all of these options and formulas, how do you know which grease is the right selection for your valuable equipment? Equipment owner's manuals provide valuable lubricant guidelines that should be followed. The OEM (Original Equipment Manufacturer) generally provides information regarding the recommended grease consistency grade, oil viscosity, dropping point and the degree of extreme pressure protection that is needed for the application. Also, think about what products have been used with success in the past and what traits would be beneficial to improve. Consider the use of greases that improve the characteristic that is causing failures in the application. For example, if a bearing is failing because of wear, you may want to use a grease with improved anti-wear performance. If the bearing is rusting, bearing life might be extended by using a grease with enhanced rust protection. If the grease is washing out of the bearing, a grease with excellent water washout protection should be considered, etc. You also have the ability to contact the grease manufacturer directly. Oftentimes, these companies will have dedicated lubrication experts who can help you evaluate your equipment needs and find the best heavy-duty grease lubricant for you.

Grease Point Identification
Once the proper grease or greases have been selected, the next important step is to identify the points that need greasing. The best place to review which points need greasing is your owner's manual. A good rule of thumb is that any contained component that turns, rubs, or oscillates against another metallic surface will require lubrication.

Common points that often require lubrication include:

  • Rotating driveshaft universal joints
  • Mower deck spindles
  • Steering components
  • Loader pivot points
  • Backhoe pivot points
  • Hitch components

Often overlooked places include controls like joystick components, brake pedal linkages and other tools or implements used on the tractor. Once you have properly identified all of the points that need greasing, it can be helpful to create a spreadsheet to keep track of the points and serve as a preventative maintenance checklist.

Preventative Maintenance Frequency
While the frequency of your preventative maintenance activities will mostly be condition related, it is also helpful to consult your owner's manual for interval suggestions, both for normal operational runs and runs that are working against outside environmental conditions.

Once your grease points have been identified and your preventative maintenance schedule has been developed, it is still critical to be aware of other variables that could potentially affect your lubrication needs. This includes factors such as extreme weather, extended use time, and exposure to moisture or other chemicals.