Author: Geof Fowler, Tractor.com Published: April 16, 2019

Tractors with many metal-to-metal joints, bearings, and swing points operate in a wide temperature range under dusty, dirty, and often humid conditions. Lubricants need to be used at these points to help prevent premature wear, Corrosion and malfunction. The use of grease can be traced back to the use of the Egyptians on the axles of tanks, and it is a common and cheap lubrication method.

So what is this magical lubricant? Grease is nothing more than a heavy oil with soap (often) to make it thick enough to stay in place. In this article, we will introduce grease classification and testing, some of the different types that need to be considered, identification of tractor lubrication points, and lubrication frequency to help develop a preventive maintenance (PM) plan.

Grease is graded/rated by the standard established by the National Lubricating Grease Association (NLGI) and confirmed/verified by the American Society for Testing and Materials (ASTM) standards. The consistency of the grease is determined by placing a penetrometer (funnel) on a 77F smooth grease cup and measuring the penetration of 1/10 mm after 5 seconds. The greater the penetration, the softer the grease/the less the grease, the harder and the lower the corresponding NLGI number. NLGI divides grease into nine grades: 000, 00, 0, 1, 2, 3, 4, 5, and 6, where 000 is a high-permeability formula for concentrated systems at colder temperatures, and 6 is for more Thermal stress conditions for low-permeability formulations for multiple applications. Most greases today belong to the middle NLGI 1, 2 and 3 grades, with NLGI 2 being the most common.

The ASTM test standards used include Timken OK load (performance measurement of extreme pressure additives), dropping point (temperature grease changes from semi-solid to liquid), water washing (grease resistance to water washing), oil separation (separation tendency) Under high temperature), anti-corrosion and abrasion. These test standards are technical and not entirely necessary for grease users, but each standard helps define the performance and quality of the grease.

Greases are generally divided into two categories: greases that use soap as a thickener and greases that use a non-soap-based thickener. Approximately 90% of the available grease belongs to the soap thickener series. The formula ratio is generally 80% to 95% oil, 2% to 20% soap thickener and 0% to 15% additives. Thickeners used include calcium, sodium, barium, lithium, lithium complex, calcium complex, aluminum complex, clay, polyurea, and calcium sulfonate. Additives can improve the performance of grease under various conditions, including antioxidants, defoamers, anti-wear agents, rust inhibitors and corrosion inhibitors. As important as thickeners and additives, the base oil and its viscosity ultimately determine the performance of the grease.

The types of base oils used include mineral oil (paraffin oil and naphthenic oil), synthetic oil (PAO, ester, PAG, and alkylbenzene), natural oil (vegetable oil), and high-performance oil (silicone oil and fluorinated oil). Most greases will be formulated with American Petroleum Institute (API) Group I and Group II base oils. These are suitable for most applications. In extreme temperature applications, or applications that require extended lubrication intervals, synthetic base oils may be the best choice.

So which grease should be used? As always, the best starting point is your user manual. But even there, you may not find all the answers. For example, John Deere’s user manual may list John Deere Multipurpose SD Polyurea Grease or John Deere HD Lithium Complex Grease as the first choice. Below is a comment stating that if you do not use the preferred grease, be sure to use a general purpose grease with NLGI grade 2. NLGI No. 2 grease has such a wide range of options, choosing the right grease for your tractor will be largely affected by your specific operating conditions. Therefore, it is important to fully understand what grease manufacturers use and do, and why this article has spent so much attention here.

Once one or more suitable greases have been selected (more on that later), it is equally important to determine the lubrication point. Again, the best place to identify these lubrication points is your user manual. In fact, anything that rotates, rubs, or vibrates on another metal surface needs to be lubricated. Common points will be the rotary drive shaft universal joint, lawn mower deck spindle, steering components, loader pivot point, backhoe pivot point and hook assembly. Places that are often overlooked may include controls such as joystick assemblies, brake pedal linkages, and tools used by tractors. Once these points are determined, a convenient spreadsheet checklist can help remind the locations of these points and serve as a PM checklist.

The frequency of preventive maintenance will depend on the conditions, but it is important to understand the interval recommended by the manufacturer. Likewise, the user manual is your friend. Among them, you may find recommended intervals during normal use, such as once every 50 hours. In extreme muddy and/or humid conditions, these intervals may be reduced to every 10 hours of use or once a day, whichever comes first. Once the lubrication points are determined and the PM plan is developed, it is still important for operators to be aware of variables that may change, such as extreme weather, longer usage times, and exposure to moisture and chemicals.

Regarding the description of zerks, these accessories were patented by Oscar U. Zerk in 1929 and then produced under license by Alemite Corp.. Zerk or alemite fittings use a small bearing ball that is pushed away by the pressure of the grease gun to allow the grease to enter, and then rebound the sealing fitting when the pressure is released. After lubrication, it is important to wipe off the excess grease left on the outside of the fitting so that the grease gun will not push contaminants into the bearing or fitting during the next lubrication. Forget this simple step, premature failure will always follow.

Although in many industrial applications, the use of sealed bearings (bearings with a sealed oil tank designed to be lubricated during the bearing’s design life) and grease-free accessories (usually coated with polymers such as polytetrafluoroethylene) has become more In general, most tractors and related implements still require PM procedures, which include regular lubrication to keep everything in top operating condition. In order to make the most of the tractor and the tools it uses, the operator needs to fully understand this often overlooked and often simplified lubricant.

A version of this article was originally published on our partner website Tractor.com. It has been updated and adapted for AGDAILY.