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Measuring the Success of an Oil Analysis Program

In a world where budgets rule the day and any additional program is shut down if merit cannot be found in it, being able to prove the success of your oil analysis program is critical. But how does one go about proving that the implementation of a program has stopped or reduced failures when there isn’t a big incident to compare it against? Simple, we start in the past to get to where we need to be in the future.

Documentation is always critical especially when we’re trying to build a case to implement some new measures. If previous failures have been documented, then the associated downtime and expenses such as additional labour, parts or expedited shipping and handling should also be taken account of. By detailing the costs associated with a failure or unplanned downtime from a lubrication issue, we can use this data to help determine the ROI of implementing the oil analysis program.

Measuring the success of an Oil Analysis Program

We need to then identify the times that the oil analysis program alerted the maintenance team about an upcoming issue or something that didn’t seem right which turned out to be a failing part or perhaps something that would cause some unplanned downtime. In these cases, we need to note what challenge we stopped or reduced the risk of occurring. By assigning a value to the failure that we prevented, we can then develop the ROI on the implementation of the oil analysis program.

Oil analysis can be a game changer for our maintenance teams in our fleets. It can help them to make more informed decisions allowing them to plan maintenance activities better and even reduce unwanted downtime. Oil analysis can be that hidden tool in our utility belt if we make use of it and implement it to help our fleets.

References

Bureau Veritas. (2020). The Basics of Oil Analysis Booklet. Retrieved from Bureau Veritas: https://oil-testing.com/wp-content/uploads/2020/08/Basics-of-Oil-Analysis-Booklet-2020V_compressed-1.pdf

Rensselar, J. V. (2016, January). Unraveling the mystery of oil analysis flagging limits. STLE TLT magazine.

Find out more in the full article in Equipment Today Magazine.

Used Oil Analysis

Implementing Oil Analysis for a mixed fleet

Now that we understand the value that oil analysis can bring, we need to be able to implement it, especially in mixed fleets. It is critical to clearly define the objectives of this program to ensure that we can monitor the value that oil analysis brings to our operations.

Ideally, the main objective of this program is to be able to monitor the health of the assets and prevent or reduce the possibility of a major failure or unplanned downtime. While it would be great to monitor the health of all the assets, this may not be entirely necessary.

Assets can be broken down into three main categories: critical, semi-critical and non-critical. The critical assets are the pieces of equipment which if they fail, can negatively impact the business. Semi-critical assets are those which if they fail, may have some impact on the business while non-critical assets are those whose failure do not impact on the business.

Implementing Oil Analysis for a mixed fleet

Depending on the nature of the business or the operations / projects which are ongoing at any point in time, your critical assets can switch in terms of priority to become semi-critical or a non-critical asset. For instance, if there was a job which required the use of a crane, then this would be our critical asset. However, if there was a job which did not require the use of a crane, then this asset becomes non-critical.

If we were dealing with the manufacturing industry where there are stationary pieces of equipment and a standard procedure, then the criticality of assets will not change as compared to a mixed fleet operation where contractors may have different jobs and require varying pieces of equipment.

Now that we’ve identified the critical assets / pieces of equipment, the sampling frequency must be determined. For critical assets, these may require some specialty tests as we want to ensure that we are alerted at the earliest possible time about an impending failure.

(Bureau Veritas, 2020) provides some guidelines for oil sampling as per figure 4 below. However, the OEM guidelines should be adhered to once they exist. Even though the sampling intervals state 250 or 500 hours, these must be in accordance with the OEMs guidelines regarding maintenance as well.

Figure 5. Guidelines for sampling as per Bureau Veritas, 2020

Typically, some OEMs may require an oil change at around 500 or 1000 hours (depending on the unit). If we only take the oil sample at the end of the life of the oil, then we are monitoring and trending how the oil ages at this point in time. However, if we’re trying to extend the oil drain interval of a component, then we would need to develop shorter intervals to monitor how the health of the oil is progressing and if it can indeed last for a longer time. If we’re attempting to extend the oil drain interval, then this should be done at increments of about a quarter of the usual interval.

Find out more in the full article in Equipment Today Magazine.

Used Oil Analysis

How to read an Oil Analysis report

While oil analysis can help our teams identify more information about the condition of the oil, we still need to ensure that they can read the oil analysis report and put measures in place to deal with the issues which may arise. In the example below, we will look through a typical diesel engine report as provided by ALS Tribology lab featured in STLE’s TLT magazine as shown in Figure 1.

Figure 1. First page of Diesel Engine oil report adapted from Rensselar, 2016

Most labs try to make it very easy for the report readers to assess the health of the oil, at a first glance. They usually implement a traffic light system where the status of the oil is highlighted. In this case, this oil has a normal rating indicating that the oil is still in good health and there isn’t anything to be concerned about yet as shown in Figure 2.

However, one of the main premises of oil analysis is the ability to spot trends over time and from this report, we can see that the oil may not have always been in a good condition as shown in figure 3. Each column represents an oil sample from a different date, so at a quick glance we can see that for two of the results, the oil was not in a good state whereas for the other results they remained in the normal region.

Figure 3: Changing condition of the oil

Figure 2: Current condition of the oil

One question that often gets asked is, “What is the normal region?”. Most oil analysis labs have collected data from OEMs which explicitly state the alarm limits for their pieces of equipment. As such, for each component, a lab should have matching data for alarm limits for the oil in that component. If none exists, then the lab may use a general industry guideline for these limits.

Therefore, if the actual value of the oil either exceeds or is below the limit, then this value will be flagged and the user notified. As seen in the report, there are basic sections into which these values are broken up, namely; metals, contaminants, additives and physical tests. Depending on the OEM, there will be different limits for these values.

However, our teams need to be able to identify what the presence or absence of the elements mean for different components.(Bureau Veritas, 2020) compiled a listing to help report readers understand this better as seen below.

Figure 4. Identify what the presence or absence of the elements mean for different components (Bureau Veritas, 2020)

Armed with this information, our teams can make more informed decisions. If they start seeing the quantity of Chromium increasing in their engines then this could be a sign of wear on the Liners and rings, shafts, valve train, bearings, shafts and gears, seals. Therefore, some investigations can begin on these components and possible wear can be addressed before the component gets damaged to the point that it can no longer function. Similarly, if they notice particular additives decrease over time such as zinc, then this could indicate that the antiwear additive is being depleted at a faster rate. These tables can guide report readers on what is actually occurring in their oils allowing them to properly plan for maintenance activities.

Find out more in the full article in Equipment Today Magazine.

Used Oil Analysis

What is Oil Analysis?

When we think about the various tools available to our maintenance team, we often think about physical tools such as a screwdriver, wrench or possibly even a hammer (if used in the right circumstances!). However, we don’t think about some of the methods we could employ which can make our maintenance teams more efficient or our equipment more reliable.

One such method is oil analysis and while it may not be at the forefront of our minds when thinking about increasing the reliability of the fleet, its impacts can be very significant once utilized properly. In this article, we will talk about the implementation of oil analysis for a mixed fleet of equipment, the impact of this program and the ways that the success of this method can be measured.

What Is Oil Analysis?

If you’ve ever drained the oil from the sump of a diesel engine, then you would know that it’s a messy process. Typically, when this oil is drained, the mechanic can tell you a few things about what happened on the inside of the engine without going to a lab.

For instance, some mechanics may place a magnet in a sealed bag and drop this into the drained oil. When they remove the bag, if there are metal filings stuck to the outside of the bag with the magnet, then that means there is some significant wear occurring on the inside of the engine. Similarly, if there is a tinge of a rainbow colour on the surface of the drained oil, that could mean that fuel is getting into the oil system and there may be an issue with one of the fuel injectors.

While these methods may not be able to precisely tell us how much fuel or wear (or what type of wear metal was present), they do provide some indications of what’s happening on the inside of the equipment. This is where oil analysis can be the game changer for our mechanics and our teams leading the reliability initiative.

With oil analysis, we can accurately and quantitatively trend the presence or absence of certain characteristics of the oil and what it contains. In this instance, we are able to correctly identify the wear metals present in the oil and trend whether these values increase or decrease over time. This can help our mechanics to figure out exactly where the wear is coming from as they would be able to identify the parts of the engine which are associated with the increase in the particular wear metal from the report.

Additionally, they can become more aware of other important parameters such as viscosity or TBN (Total Base Number) which they would not have been able to quantify without oil analysis. They can also get information on the decreases in additives or increases in contaminants which can allow them to identify or troubleshoot these issues in advance.

Find out more in the full article in Equipment Today Magazine.

Storage & Handling of Lubricants

Is Oil Contamination Affecting the Performance of Your Equipment?

Often, the particles we don’t see are the ones that affect us most. For instance, we can’t see bacteria or germs but those can easily get into our body and make us sick. Something similar occurs with our equipment and the lubricants which are used to help them work more efficiently. SKF notes that contamination and ineffective lubrication are responsible for 51% of bearing, coupling, chain and other machine component failures in equipment.

Logically, if we control the amount of contamination, we can control the number of failures and all the resulting consequences, such as unscheduled downtime and rush expenses (for called out or specialized labor and parts). In this column, we explore how contamination can impact the performance of your equipment, ways to combat contamination and some examples.

Is Oil Contamination Affecting the Performance of Your Equipment

What Is Contamination?

Contamination is anything that is foreign to the environment. For machinery lubricants, these are usually classified in three main groups: Gases, liquids and solids. When speaking about gases, this can be air or other gases (such as ammonia or methane) that encounter the lubricant. For liquids, this includes water, fuel or any other liquid that can enter the lubricant, particularly other lubricants or liquids that can be added knowingly or unknowingly. Lastly, solids can mean dirt (from outside the process), metals (from inside the machine) or any other solid particle in the lubricant.

Gases

Gases are the most unsuspected forms of contamination since many people believe that a gas will not affect the lubricant or by extension the machine. However, if air gets trapped in a closed loop system, this can lead to foaming (if the oil makes its way to the surface) or to microdieseling if it remains entrained in the oil.

With foaming, this typically occurs in gearboxes or equipment that are subjected to high churn rates of oil. Foam can settle at the top of the oil and cause the lubricant to not form a full film to separate the contacting surfaces. As such, this can lead to wear of the equipment.

On the other hand, microdieseling or the entrainment of air in the system can also prove to be dangerous because the trapped air bubbles can give rise to temperatures in excess of 1,000°C if they move between different pressure zones. This will lead to oil degradation, often producing some coke or tar insoluble as final deposits. Additionally, this trapped air/gas can also advance to cavitation inside the equipment.

Additionally, if the gas trapped is not air but a catalyst to a chemical reaction, this can incite further or more rapid degradation of the oil making it no longer able to protect the equipment. Therefore, identifying the presence of unwanted gases in your lube oil systems or preventing their entry in the first place is important.

Liquids

Liquids are trickier than gases because they somehow seem to enter the lubricant more easily or get mixed in unknowingly. When a liquid enters a lubricant, it can directly impact the viscosity of the lubricant, either increasing it or decreasing it. In either of these cases, this can be detrimental to the equipment.

If the lubricant’s viscosity increases above the essential value, then the machine will demand more energy to execute its required functions. This will directly impact its efficiency and energy consumption. On the other hand, if the lubricant’s viscosity decreases outside of the essential value, then the lubricant may not be able to adequately protect the contacting surfaces. Therefore, this increases the amount of wear that may occur on the inside of the machine.

Typically, water and fuel are the most common culprits of liquid contamination. These can easily get into your lubricants through poor storage and handling practices. Water can increase the viscosity of your lubricant and cause some additives to drop out of it, reducing its level of protection. Fuel will decrease the viscosity and possibly add to the fire risk of the system. Both can severely damage your equipment.

Another common culprit is the mixing of different types of oil. On an average day, things are busy, and people can get confused and pick up the wrong oil to perform a top up on a system. If we add gear oil or hydraulic oil to an engine oil system, we can have a catastrophe! These oils would have different viscosities, and their additive packages (or even base oils) may not be compatible. This can cause the equipment to stop working, leading to unplanned downtime and then exorbitant resources to get the machine operating again.

Solids

Solids can easily get into our equipment either from the outside or the inside. If there are openings to allow solids to enter then they will. However, sometimes solids enter our lubrication systems without us knowing. This can happen through poor storage and handling practices.

Once solids enter the system, they can:

Increase the viscosity of the oil
Increase the amount of wear occurring inside the equipment
Act as a catalyst (depending on their nature)
Block smaller clearances causing unwanted downtime in the equipment

Typically, solids are usually dirt, which can enter from outside the equipment. However, these hard particles can cause some metal to be damaged on the inside the equipment which can then lead to the metal being a catalyst for another degradation mode.

Some solids are formed inside the equipment as deposits. These deposits can occur if another contaminant (liquid, gas or another solid) enters the system and reacts with the oil to produce them. As such, these deposits may clog injectors, other valves or tight clearances causing the equipment to malfunction.

Find out more information in the article in the Equipment Today Magazine.

Oil Properties

The Future of Gear Oils

According to (Industry ARC (Analytics. Research. Consulting), 2024), the global industrial gear oil market size is forecasted to reach USD 5.2 B by 2027. While the Asia-Pacific market holds a significant market share for industrial gear oils in 2021 at around 56.2%, it is interesting that its nearest rival is Europe, at 17.7% or less than ⅓ of its size.

The rise in the Asia Pacific market can be accounted for due to the increase in the rising population and, by extension, the needs of that population and the service sectors they support, including the energy, oil & gas, construction, and steel industries. The figure below depicts the global industrial gear oil market revenue share by Geography for 2021.

Figure 6: Industrial Gear Oils (Mineral & Synthetic) Market Revenue Share by Geography 2021 adapted from (Industry ARC (Analytics. Research. Consulting), 2024)

From the research conducted by (Industry ARC (Analytics. Research. Consulting), 2024), helical gears appear to be the most popular choice for industrial gears. Interestingly enough, synthetic gear oil held the largest market share and is forecasted to grow by a CAGR of 5.6% for the forecasted period of 2022-2027.

Smaller gearboxes are being manufactured, tasked with outperforming their previous counterparts and producing more torque in a smaller space. With the advent of better, more precise machining tools for gears, there is an increase in the amount of pressure these gears now must handle in smaller spaces.

As such, we will continue to see the rise in the use of synthetic gear lubricants formulated to handle these extreme conditions, as well as more advanced additive packages that can help minimize foaming, reduce oxidation, and aid in the demulsibility of these oils.

References

Industry ARC (Analytics. Research. Consulting). (2024, September 04). Industrial Gear Oils (Mineral & Synthetic) Market - Forecast(2024 - 2030). Retrieved from Industry ARC: https://www.industryarc.com/Report/20008/industrial-gear-oils-mineral-and-synthetic-market.html

Mang, T., & Dresel, W. (2007). Lubricants and Lubrication - Second Edition. Weinheim: WILEY-VCH GmbH & Co. KGaA.

Mang, T., Bobzin, K., & Bartels, T. (2011). Industrial Tribology - Tribosystems, Friction, Wear and Surface Engineering, Lubrication. Weinheim: WILEY-VCH Verlag GmbH & Co. KGaA.

Pirro, D. M., Webster, M., & Daschner, E. (2016). Lubrication Fundamentals - Third Edition, Revised and Expanded. Boca Raton: CRC Press, Taylor & Francis Group.

Rensselar, J. v. (February 2013). Gear oils. Tribology and Lubrication Technology - STLE, 33.

Sander, J. (2020). Putting the simple back into viscosity. Retrieved from Lubrication Engineers: https://lelubricants.com/wp-content/uploads/pdf/news/White%20Papers/simple_viscosity.pdf

Santora, M. (2018, March 20). Tips on properly specifying gear oil. Retrieved from Design World: https://www.designworldonline.com/tips-on-properly-specifying-gear-oil/#:~:text=CLP%20Gear%20Oils&text=Often%2C%20a%20gear%20manufacturer%20will,a%20CLP%20polyglycol%20PAG%20oil

Find out more in the Precision Lubrication Magazine article here!

Oil Properties

Gear Oil Storage and Handling

Similar to most oils, gear oils should be stored in a clean and dry space. Often (especially in the past), these gear oils see a settling of the additives to the bottom of the container, indicating a slightly shorter oil life span than other lubricants. However, this is no longer a highly occurring incident with the advancements in additive technology and improved blending practices.

As usual, it is always best to adhere to the OEM’s expiry dates for these products, as different OEMs recommend varying storage times for their products. Generally, synthetic lubricants have an estimated shelf life of 5-10 years, while mineral oils usually last for around 2-3 years, but this is heavily dependent on the OEM and storage conditions.

In some cases, customers tend to store these drums outside in the elements as it makes it easier for them to be readily accessible for decanting into the equipment. However, in these environments, the drums can collect water, which will enter the oil and then, by extension, enter the gearbox. This can cause issues for the equipment and lead to accelerated oil degradation.

Ideally, these oils should be stored in a cool, dry place with ready access to decanting equipment where the decanted oil will not be easily contaminated. Many industrial gearboxes typically require larger quantities of oil, and decanting can take place directly from the drum into the equipment or via a pump.

In these cases, the level of contamination must be minimized by ensuring that the fittings, hoses, etc., are clean and have not been used to decant other types of oils.

Find out more in the Precision Lubrication Magazine article here!

Oil Properties

Degradation of Gear Oils

The first set of additives to decrease in gear oils is often the antiwear or extreme pressure additives. This is no surprise, as these oils are subjected to high levels of wear and must withstand extreme pressures. One can also notice a decline in the rust and oxidation additives or even a change in the air release values.

All these properties significantly impact how a gear oil functions. As such, they should be monitored when establishing the health of the oil.

When monitoring the health of these lubricants, some guidelines can be utilized. If there is a change in viscosity of either ±10%, one should look for any other correlating changes.

Typically, if the viscosity increases by 10%, we’re looking at increases in wear metals or the risk of oxidation and development of some deposits in the oil or even contamination of the oil with some water. However, for a decline of 10%, one can expect some form of contamination, typically fuel or another substance which will thin out the lubricant.

The lubricant’s warning levels for wear metals will vary depending on the manufacturer/OEM. However, any consistent rise in wear metals indicates that some component on the inside of the equipment is slowly wearing away.

Find out more in the Precision Lubrication Magazine article here!

Oil Properties

Gear Oil Characteristics and Naming Systems

From the information covered thus far, we can appreciate that gear oils need to accommodate many changes to their environment. A few characteristics stand out when looking at industrial gear oils (Mang, Bobzin, & Bartels, Industrial Tribology—Tribosystems, Friction, Wear and Surface Engineering, Lubrication, 2011).

These include viscosity-temperature, Fluid Shear Stability, Corrosion and Rust Protection, Oxidation Stability, Demulsibility and Water Separation, Air release, Paint Compatibility, Seal Compatibility, Foaming, Environmental, and Skin Compatibility.

Gear Oil Characteristics and Naming Systems

Depending on where you are in the world, you may use a different system to classify gear oils. The ISO Viscosity grade system is used internationally, but the AGMA (American Gear Manufacturer’s Association) system is used in the Americas and some parts of Asia. A chart can be used to move that across these grading systems, as shown below in Figure 5.

Figure 5: Various gear oil grading systems as adopted from (Sander, 2020)

As per (Sander, 2020), the AGMA numbers have some particular meanings as stated:

No additional letters (only a number) – Contains only R&O additives
EP – Mineral oil with Extreme Pressure additives
S – Synthetic gear oil
Comp – Compounded gear oil (3-10% fatty or synthetic fatty oils)
R – Residual compounds called diluent solvents which reduce the viscosity to make it easier to apply

Another rating that is seen a lot is the CLP rating. This is a German oil standard defined by ASTM DIN 51517-3, in which the test requirements to meet the CLP specification are documented.

This DIN standard covers petroleum-based gear lubricants with additives designed to improve rust protection, oxidation resistance, and EP protection. Some typical classifications seen are CLP-M (which represents mineral gear oil), CLP HC (which represents synthetic oils [SHC, PAO, POE]), and CLP PG (which represents polyglycol PAGs), according to (Santora, 2018).

There are three main DIN 51517 classifications as per (Rensselar February 2013), namely;

DIN 51517 CGLP – contains additives that protect from corrosion, oxidation, and wear at the mixed friction spots and additives that improve the characteristics of sliding surfaces
DIN51517-3 CLP – contains additives that protect against corrosion, oxidation, and wear in the mixed friction zone
DIN 51517-2 CL – contains additives that protect against corrosion and oxidation suitable for average load conditions

The above are some of the more prevalent naming systems for industrial gear oils, and they are found on most gear oils globally.

Find out more in the Precision Lubrication Magazine article here!

Oil Properties

Is there more than one type of gear?

Gears are used in all aspects of life, from bicycles to tiny watch gears, car transmissions, and even highly specialized surgical equipment. Gears keep the world moving. However, when they move, they often rub against each other, and if this friction is not managed, it can cause wear and eventually lead to significant damage or failure. This is where gear oil makes a difference.

In this article, we will explore the various types of gear lubricants, their composition, how they degrade, some storage and handling tips, and what the future holds for these types of oils.

Figure 1: Different types of gears according to (Mang & Dresel, Lubricants and Lubrication – Second Edition, 2007) Chapter 10

If you’re familiar with gears, you know that despite the standard emoji keyboard, more than one type of gear exists. There are several types of gears, each suited for various applications. As such, each application will have varying environmental conditions, which will require specialized lubricants to reduce friction and wear.

One of the main operational conditions for gears is the transfer of torque. Even when torque is transferred, gears will have sliding and rolling contact, leading to frictional losses and heat generation. Therefore, the lubricants selected for these applications must be able to significantly reduce these frictional losses and cool the gears.

As per (Pirro, Webster, & Daschner, 2016), several types of gears can be classed into three groups based on the interaction of the teeth of these gears and the types of fluid films formed between the areas of contact:

Spur, Bevel, Helical, Herringbone, and spiral bevel
Worm gears and
Hypoid gears

Figure 1 shows some of the types of gears which exist.

It must be noted that hypoid gears transmit motion between nonintersecting shafts at a right angle. Additionally, there is a difference between rolling and sliding.

Rolling indicates continuous movement, whereas sliding varies from a maximum velocity in one direction at the start of the mesh through zero velocity at the pitch line and then back to maximum velocity in the opposite direction at the end of the mesh, as seen in Figure 2.

According to Mang, Bobzin, and Bartels (Industrial Tribology—Tribosystems, Friction, Wear and Surface Engineering, Lubrication, 2011), hypoid gears require heavily loaded lubricants. These should have high oxidation stability, good scuffing, scoring, and wear capacity, as the tooth contacts have a high load.

The lubricant must also have a high viscosity at operating temperature such that the formed film can sufficiently support the load while cooling the gears.

Conversely, hydrodynamic gears such as torque converters, hydrodynamic wet clutches, or retarders require high oxidation stability characteristics but do not need good scuffing or scoring load capacity characteristics. Unlike hypoid gears, hydrodynamic gears experience viscosity-dependent losses, so they must have a lower viscosity at operating temperature.

Figure 2: Meshing of involute gear teeth. These photographs show the progression of rolling and sliding as a pair of involute gear teeth (a commonly used design) pass through mesh. The amount of sliding can be seen from the relative positions of the numbered marks on the teeth adapted from (Pirro, Webster, & Daschner, 2016), Chapter 8.

According to (Mang & Dresel, Lubricants and Lubrication – Second Edition, 2007), there are some frequent failure criteria for gears and transmissions, including:

Extreme abrasive wear
Early endurance failure, fatigue of components in the form of micropitting and pitting
Scuffing and scoring of the friction contact areas

Continuous abrasive wear is usually observed at low circumferential speeds and during mixed and boundary lubrication. Typically, continued wear can cause damage that extends to the middle sector of the tooth flank. Understandably, lubricants with a high viscosity and a balanced quantity of antiwear additives promote a higher tolerance to wear.

Micropitting can be observed on tooth flanks at all speed ranges. Those with rough surfaces are prime candidates for micropitting. Typically, this develops in negative sliding velocities or the slip area below the pitch circle.

Usually, microscopic, minor fatigue fractures occur first, which can lead to further follow-up damage such as pitting, wear, or even tooth fractures. A lubricant with a sufficiently high viscosity and a suitable additive system can help reduce this type of fatigue.

At predominantly high or medium circumferential speeds, scuffing and scoring of the tooth flanks occur, and the contacting surfaces can weld together for a short time. Due to the high sliding velocity, this weld usually breaks, causing scuffing and scoring.

Typically, this damage is seen on the corresponding flank areas at the tooth tip and root, which experience high sliding velocity. In this case, lubricants with higher EP (Extreme Pressure) additives can help reduce this damage.

According to (Ludwig Jr & McGuire, March 2019), the type of gear can aid in determining the most appropriate industrial gear oil. The following table is an adaptation from the article:

Table 1: Gear type and appropriate lubricant adapted from (Ludwig Jr & McGuire, March 2019)

As per (Mang & Dresel, Lubricants and Lubrication – Second Edition, 2007), transmission gears can be broken down into two main types: those with a constant gear ratio and those with a variable gear ratio. These can be seen in Figures 3 and 4 below.

Figure 3: Gears with a constant gear ratio adapted from (Mang & Dresel, Lubricants and Lubrication – Second Edition, 2007), Chapter 10

Figure 4: Gears with a variable gear ratio adapted from (Mang & Dresel, Lubricants and Lubrication – Second Edition, 2007), Chapter 10

Find out more in the Precision Lubrication Magazine article here!

Tagged: engineer

What Is Oil Analysis?

What Is Contamination?

Gases

Liquids

Solids

References