Choosing the Right Gear Oil
Like all the other components of a gearbox, the right gear oil will go a long way in allowing a given gearbox to achieve its optimum performance. Consequently, the end user will enjoy the benefits of greater energy efficiency, lower operating temperature, and a lower rate of wear and tear. However, when it comes selecting the right gear oil, there are many factors to be considered, including the type of gears in the gearbox and the service in which the gearbox will be operating. Below is a rundown of some important issues you need to keep in mind when selecting gear oil for any given application.
Gear Oil Viscosity Matters
Choosing the most appropriate gear oil viscosity is sometimes straightforward. All you need to do is consult the maintenance manual. However, the maintenance manual may not always be available. Besides, the conditions under which the gearbox operates may differ from those specified in the manual. Thus, it is important to understand the fundamental approach for viscosity selection.
To this end, you have to remember that viscosity of a gear lubricant is basically meant to ensure that there is the required film thickness on the gear tooth surfaces at a particular operating temperature, speed, and load to minimize asperity contact. Since determining the load may not be possible, the speed is assumed to be the determining factor. To get the gear oil with the most appropriate viscosity for your given application, you can use a simple method such as the American National Standard Institute (ANSI) and American Gear Manufacturers Association (AGMA) standard ANSA/AGMA 9005-F16. In this method, based on the viscosity index, speed, and operating temperature, the recommended gear oil viscosity is read from one of several charts.
Check out the Additives
Having selected the right viscosity grade, you then have to shift your attention to selecting the right type of gear lubricant. Some common variations include anti-scuff and R&O (rust and oxidation inhibited). The anti-scuff gear lubricants are also known as extreme pressure or EP lubricants. This is because they have special additives that react with the metal surface to form a protective layer, which enhances their load carrying capacity. On the other hand, R&O gear oils do not contain anti-scuff additives and are, therefore, best suited for use in gearboxes which operate under low to moderate loads.
Remember to Consider the Base Oil Type
The base oil goes a long way in determining the quality of a given gear oil. Mineral oil based gear oils are known to perform satisfactorily in many applications. Synthetic hydrocarbon (polyalphaolefin or PAO) based gear oils are highly resistant to thermal and oxidative degradation, and this makes them preferable in applications where higher temperatures are involved. Synthetics also do well in applications with low ambient temperatures due to their lower pour points and higher viscosity index. The high viscosity index associated with synthetic oils also makes them ideal for applications with a wide ambient temperature range, eliminating the need to change the gear oil on a seasonal basis. Another type of synthetic fluid, polyalkylene glycol or PAG, is used in high quality worm gear oils and can improve the energy efficiency of that type of gearbox.
Overall, it is apparent that although choosing the right gear oil for a given application may be a straightforward process, things may get a bit confusing when the application manual is unavailable or the conditions under which the gearbox operates differ significantly from the conditions specified in the maintenance manual. However, you can follow the above-discussed steps to select the best lubricant for your gearbox. You can also get in touch with our gear oil experts to be sure that you are using the optimum lubricant for your application and situation.