How Important is Oil Level Control in Optimizing Bearing, Gear and Engine Reliability?

Paul Farless, Noria Corporation

Oil Level Control

Often times in machinery lubrication, we preach precision lubrication. What exactly does that mean? Regarding the act of lubricating, it means utilizing meticulous calculations to determine the most accurate lubricant type, volumes and frequencies needed to reach optimal machine performance and machinery life. The goal of any lubrication program across the board is to decrease downtime and machinery failures. Here is where I would like to point out some of the obvious and not-so-obvious key players in precision lubrication, one of which is proper lubricant level (volume).

What is the proper lubricant level, and why is that specific amount the “proper level?” The proper level is simply the level that allows for optimal performance of the component. What is optimal performance? It is the point where your machine will have the maximum extended lubricant life and component life. There are a couple of key variables used to decide the correct amount of oil:

  • Size - Whether it is a bearing, gearbox, motor, pump or hydraulic system, size plays a key role in deciding how much lubricant a component should receive. Larger bearing sizes in greased applications will obviously take a larger amount of grease; larger reservoirs in oiled applications require larger volumes of oil. This is the no-brainer of lubricant levels.
  • Speed - Speed affects grease application volumes somewhat differently than oiled applications due to lubricant dispersion needs and required film thickness. For instance, a slow-moving greased bearing will more than likely need to have the grease packed into the bearing at a higher volume during installation because the grease will not be properly dispersed due to the low speed. Slightly less will be required on a higher speed bearing where the grease will be more easily dispersed throughout the bearing a lot quicker. However, the load and the speed will affect the viscosity needed for proper lubrication. As far as oiled applications go, splash lubricated components at higher speeds may require less oil volume in order to reach proper fluid film thickness. A lower speed splash lubricated system may require a higher volume. That is the effect of speed on lubricant levels.

The Importance of Inspections and Leak Detection

Routine machinery inspections are paramount to a reliable machinery lubrication program. The members of the lubrication team aren’t the only ones who need to be performing inspections. Inspections are a responsibility for every person working at the facility: operators, maintenance, lubricators, etc. Nobody knows the plant quite as well as the people working in it every day. Pay attention to the sounds, smells, vibrations and especially machinery lubrication levels and leaks as you’re walking the floor. We need to utilize all of our senses to maintain a vigilant watch over our facility’s health and condition. A lot like our own body, we need to take care of it with periodic health checks such as fluid pressures and levels, broken or fractured components, and behavioral health. We always train the facilities that we visit to “get to know your plant.”

Damages and Hazards Caused by Overfilling

If you have taken any trainings with Noria or have dealt with any of the consultants, you will often hear us say, “clean, cool and dry.” These are three of the most important conditions of any lubricant. When it comes to overfilling, you run the risk of increasing friction, which causes heat, which, in turn, cancels out the “cool.” When heat is produced, machines start to fail; when the machine starts to fail, it starts to break down and introduces debris and particles into the oil, which cancels out the “clean.”

Overfilling is extremely detrimental to any machine, whether over-greasing or overfilling with oil. Let’s say you over-filled a gearbox or pump: this will build pressure, which could potentially cause seals to fail. Maybe not an immediate catastrophic seal failure, but a seal failure nonetheless. When that seal fails, it will allow air, particles, water or any other airborne contaminants into your machine. When this chain of events happens, it causes machinery failure and downtime. The reliability team will then be in a reactionary maintenance mode. Proactive maintenance strategies generally start with updating your lubrication program to a progressively more proactive approach. Choose the right lubricant, viscosity, volume and application frequency, and you won’t be fighting so many fires throughout the year.

Damages Caused by Underfilling

Underfilling or starvation can cause many of the same issues as overfilling. Too little oil or grease in the component will lead to excess friction; this is where you will run a higher risk of adhesive wear due to the lack of fluid film thickness required to meet boundary film conditions. This will be especially detrimental in machines with hard starts and stops. Besides adhesive wear, inadequate lubrication will cause overheating and can lead to additive depletion and lubricant degradation. When a lubricant exceeds its upper range of temperature tolerances, the viscosity will drop quite dramatically. Viscosity is one of the most important factors to consider when selecting the proper lubricant. So, regardless of whether you choose the right viscosity and additive package for the application, if you aren’t filling it to the right volume, it will eventually be degraded and lose its proper lubricating ability.

Running Level and Down Level

Running Level and Down Level particularly pertain to large volume reservoirs with columnar level gauges. Luneta columnar gauges come equipped with a red and green level indicator to mark the oil level, both when the machine is running and not running. Otherwise, we see a lot of columnar level gauges with two lines drawn in sharpie. Although that is doing the best you can with what you have, we often recommend moving to a more tactile approach: a physical marker - maybe zip ties or colored hose clamps; something that isn’t going to be removed or wiped off easily. Believe me: your sharpie mark isn’t as permanent as you think when you work at a chemical plant.

I wanted to add this bit about columnar level gauges because they are usually installed on highly critical assets. This all comes full circle back to precision lubrication and vigilant inspections. When it’s critical to a process that simply can not have an unscheduled shutdown, ensuring you have the correct volume is absolutely paramount. Constant, vigilant inspections of the lubricant levels are a proactive approach to maintaining some of your most critical assets. Early detection of leaks, contaminant ingression, lubricant degradation, wear debris and many other conditions could potentially save the team days, if not weeks, of grueling work to get the asset back up and running.

Stored Machines

We should also take into account the lubricant levels in stored assets such as gearboxes, bearings, motors and pumps. Although they don’t need to be inspected as much as in-service assets, it is still a good idea to ensure that you have the proper lubricant level and you are circulating that lubricant through the asset, generally by rotating the shafts and inspecting for leaks and lubricant level every so often. This will ensure that your backups in storage are ready for service the very instant they need to be. I always suggest viewing it like a sports team: maintain your starters and make sure they are healthy and prepared for the game. However, you can’t forget about your bench depth. If one of your starting players goes down with an injury, you’re going to need the player from the bench to be ready and willing to take the starter’s place seamlessly.

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About the Author
Paul Farless is an industrial service technician for Noria Corporation. His duties include collecting data and preparing reports for the engineering team. Prior to joining Noria, Paul worked as an aut...