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496 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What is the most important physical property of a lubricant? |
Viscosity |
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Name two liquids that are common contaminants found in lubricants. |
Water and fuel |
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What type of base oil would have a viscosity index of 100? |
Paraffinic |
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List 5 functions of a lube oil. |
1. Reduce friction 2. Reduce wear 3. Reduce corrosion 4. Reduce heat 5. Reduce contaminant ingression. |
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When does mixed film lubrication most commonly occur? |
During start up and shut down
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What three factors determine the film thickness of a lubricant? |
1. Load 2. Speed 3. Viscosity |
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What type of oil would have a viscosity index of 0? |
Naphthenic |
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What type of lubrication is a full lubrication film established? |
Hydrodynamic |
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What is the number one reason machines fail? |
Surface degradation |
"Why Machines Fail" Machinery Lubrication 8.12.16 |
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What lubrication regime occurs under high load and low speed? |
Boundary Lubrication |
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What are the 5 rights of lubrication? |
1. The right oil 2. The right amount 3. The right time 4. The right place 5. The right attitude |
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Which oil maintains its viscosity better over a larger temperature change an oil with a high viscosity index or an oil with a low viscosity index? |
high viscoisty index |
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The Base Number of a diesel engine typically _______ with increasing service time. |
decreases |
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What two oil analysis tests would you run to determine the remaining useful life of a turbine oil? |
RPVOT (Rotating Pressurized Vessel Oxidation Test) ASTM D2272 RULER (Remaining Useful Life Remaining) ASTM ? |
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What is the largest particle that can be detected by Atomic Emission Spectroscopy? |
5 microns |
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Does the Acid Number of a turbine oil typically increase or decrease with increasing time in service |
increase |
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What type of lubrication regime is typical for a journal bearing? |
hydrodynamic |
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Why should you avoid using funnels when adding oil? |
Contamination |
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What measurement is typically used to assess a filter's efficiency? |
Beta Ratio ( Multipass Test) |
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What type of oil degradtion occurs under high temperatures when little or no oxygen is present? |
Thermal degradation |
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When an oil is oxidized, does the viscosity typically increase or decrease? |
Increase |
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Name two applications where you would expect to find rolling wear. |
1.Pitch line of gears. 2. Rolling element bearings. |
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Name 4 things that a filter cart can be used for. |
1. Transfer lubricants to storage 2. Transer oil to machine 3. Improve oil cleanliness 4. Decontaminant used oil 5. Provide contamination control functions. |
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Name 3 advatanges of buying oil in bulk |
1. Lower cost 2. Less handling 3. Lubricant available by plant's needs 4. Lower container disposal costs 5. Use of hard piping and dedicated pumps 6. Easy filtration and conditioning. |
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When oil drum must be stored outside, how should the drums be positioned? |
On their side with the bungs positioned at the 3 and o'clock spots. |
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What different states can water be in an oil? |
1. Free water 2. Emulsified water 3.Dissolved water |
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Why effect would entrained air have on a hydraulic system? |
Erratic and sluggish performance. |
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Water can exist in oil in three different states. Which one is considered the most harmful and why? |
Emulsified. Because of the high contact area with the oil and can be carried through the lube system. |
Basics of Oil Analysis p.35 |
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Name 3 (or more) contaminants commonly found in oil |
1. Particle 2. Water 3. Fuel 4. Soot. 5. Glycol |
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What is the most cost effective method to controlling particle contamination? |
Contamination exclusion. It's much cheaper to prevent contamination from entering the lube system than it is to remove the contaminant from the oil. |
Basics of Oil Analysis p. 23 |
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What are the three sources of particle ingression? |
1. Built in 2. Ingested 3. Generated |
Basics of Oil Analysis p. 24 |
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What properties of an oil do you need to know to calculate the viscosity index of an oil? |
The viscosity at 40 'C and 100 'C. |
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What is the preferred maintenance strategy and why? |
Proactive maintenance. |
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ZDDP additive performs 2 different funtions. What are they? |
1. Antioxidant 2. Antiwear |
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Name 4 lubrication regimes. |
1. Boundary 2. Mixed film 3. Elastohydrodynamic 4. Hydrodynamic 5. Hydrostatic |
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What is the smallest particle that typically can be seen by the human eye? |
40 microns |
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How many base stock categories are defined by API? |
5 Groups |
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Lubricant condition can be monitored by FTIR. Name 4 properties that can be measured. |
1. Oxidation 2. Nitration 3. Sulfation 4. Soot 5. Water 6. Glycol 7. Fuel 8. Some additives (ZDDP, etc.) 7. |
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A gearbox sample is analyzed by Atomic Emission Spectroscopy (AES) and Ferrous Density Analysis. The iron value has not increased by AES, but the Ferrous Density has increased. Explain what has happened. |
The number of iron particles greater that 5 microns has increased. |
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What does VII stand for? |
Viscosity Index Improver |
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What is a dispersant additive and what application are these additives typically used? |
A dispersant is a polar additive that envelopes the soot and keeps it from agglomerating. Typically used in diesel engines. |
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Wear particles such as copper may catalyze oil oxidation. True or false |
True. Wear metals can catalyze (speed up) oxidation and reduce the life of the oil. |
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If you mixed a SAE 30 and an SAE 50, would the result be more like a SAE 60 or and SAE 40? |
SAE 40 |
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Which mineral oil base stock would have the lower pour point? A. Paraffinic B. Naphthenic |
B. Naphthenic |
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What types of synthetics are susceptible to hydrolysis (cleavage by water)? |
Esters |
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If an oil change interval has been overextended and the level of antioxidants have been depleted. What changes might you observe? |
Darkened color Odor viscosity increase AN increase |
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What method should be used to make sure that new oil isn't stored too long? |
FIFO (First In First Out) |
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What element might you see in the oil analysis that's from an antifoaming additive? |
Si (Silicon) |
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Name 4 additives typically found in turbine oil. |
1. Antioxidant 2. Antifoamant 3. Rust inhibitors 5. Demulsifying additive |
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What is the specific gravity of water? |
1.0 |
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If an oil is insoluble in water and has a specific gravity of 1.14 is mixed with water, will it be on the top or bottom? |
Bottom. However, most mineral oils have a specific gravity of less than one and will float on top of the water. |
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What grease thickener is commonly used for multipurpose grease? |
Lithium |
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Define Tribolgy |
The study of interacting surfaces in relative motion. It includes the study of friction, lubrication and wear. |
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Name the wear mode that is reduced by use of an extreme pressure additive. |
Adhesive wear |
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How many microns are in a 0.001 in.? |
25 microns |
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1 percent is equal to ____ PPM. |
10,000 |
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An oil that has an ISO code of 19/17/14 is about how much dirtier than an oil with an ISO code of 18/16/13 |
About two times dirtier. |
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If you wanted to extend the life of a machine, what maintenance strategy might you use? |
Proactive maintenance |
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What contaminants would be removed by using a vacuum dehydrator? |
Water, solvents and entrained gases for example air refrigerants and process gases. |
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What are the three components of a grease? |
Lubricant, thickener and additives. |
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"MSDS" is an abbreviation for? |
Material Safety Data Sheet. The term has now been shortened to SDS. |
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In hydrodynamic lubrication the metal surfaces are completely separated, what friction still remains? |
Friction from the lubricant's resistance to flow, viscosity. |
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Which of the following is the best oil to use for cold start up. A. SAE 60 B. SAE 15W40 C. SAE 5W30 D. SAE 30 |
C. SAE 5W30 |
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Name some common causes for viscosity decreasing in an application. |
1. Adding the wrong (thinner) oil 2. Dilution with a fuel or solvent. 3. Viscosity index improver shearing. 4. Process fluid (gas or liquid) ingression. |
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When is hydrostatic lubrication commonly used and why?
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Hydrostatic lubrication is used on turbines and large equipment where damage may occur on start up. |
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Name 3 components in which EHD (Elestohydrodynamic) lubrication is used.
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1. Rolling element bearings 2. Gears 3. Cams and followers |
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What API Group do PAO (polyalphaolefins) fall into?
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Group IV
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How many particles greater that 10 microns are in a super clean sample bottle?
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Less than 10 particles greater than 10 microns
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What is the main disadvantage of using PET sample bottles?
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The PET bottles tend to soften or melt when taking hot temperature samples.
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Solvent refined oils fall into what API group/
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Group I
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Mixed film lubrication is a combination of what two lubrication regimes?
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Boundary and hydrodynamic
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What is a disadvantage of lubricant consolidating?
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Potential to compromise equipment that doesn't quite meet all the requirements.
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Name two types of positive displacement compressors.
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1. Reciprocating 2. Rotary |
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What ASTM method measures the ability of the oil to separate from water?
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ASTM D1401
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The Schiff's test is used to check for what contaminant?
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Glycol (antifreeze)
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A diesel engine oil's viscosity has decreased from a SAE 40 to a SAE 30 and the flash point has decreased from 440 'F to 360 'F. What contaminant is most likely present? |
Diesel fuel.
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What is a common cause of seal swell?
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Seal material is incompatible with base oil or its additives.
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Name a test that has both an upper and lower limit
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Viscosity
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Acid number (AN) and base number (BN) are both expressed in what units? |
mg KOH/g of sample. Note that KOH is not used for BN instead HCL is used for BN. |
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What wear type occurs at low speed and high load? |
Adhesive wear
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A roller bearing may lose up to ___% of its life from water before the oil becomes hazy. |
75% |
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The API gravity ______ as the specific gravity increases. |
decreases |
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How full should the sample be for an ISO 220 oil? |
half |
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Name two field tests that can be used to check if an oil has oxidized. |
1. Darkened appearance 2. Odor |
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What units is kinematic viscosity reported in? |
centistokes (cSt) |
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The Pareto Pinciple (80/20 Rule) states that |
most (~80%) of failures may be prevented by focusing on a few (~20%) of the causes |
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Which of the following is a common additive element? a) Iron b) Lead c) Phosphorous d) Copper |
c) Phosphorous |
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As an oil ages with increased service time the AN typically (decreases or increases) |
Increases |
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As an engine oil ages with increasing service time the BN typically (decreases or increases) |
decreases |
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An increase in silicon and wear metals indicates that |
Silicon (dirt) contamination is occurring and is causing abrasive wear |
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What two functions does a detergent additive perform? |
Control Deposits and neutralize acids. |
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What additive is in a multigrade engine oil (e.g, 15W40)that is not in a single grade (e.g., SAE 30) oil? |
VI Improver |
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The dropping point of a grease should be (higher or lower) than the expected operating temperature? |
higher |
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What type of wear may occur by air bubbles in a hydraulic oil? |
Cavitation |
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Name at least three types of total loss lubrication |
1. oil mist 2. drop 3. wick feed 4. spray 4 air bourne 5. hand lubrication |
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In a splash lubricated gearbox, what is the recommended oil level? |
Oil should completely cover the lowest gear tooth. |
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In a single line progressive system, what happens if one injector fails? |
All the injectors fail |
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What is most common wear mode? |
Abrasive |
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High speed couplings require special grease. Why is that? |
The centrifugal force can cause the oil and thickener to separate. |
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What is another term for corrective maintenance? |
Reactive maintenance |
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What unit of measure is used with flash point and pour point? |
Temperature |
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Is the specific gravity of a mineral oil typically higher or lower than synthetic lubricants? |
Lower |
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Name the two most common types of mineral base oils. |
paraffinic and naphthenic |
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Which would have the highest VI? paraffinic or naphthenic? |
paraffinic |
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Which would have the lowest pour point? paraffinic or naphthenic? |
Naphthenic |
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Which has a higher VI, a PAO or a solvent-refined (Group I) mineral oil? |
PAO |
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When an oil oxidizes, how does its viscosity typically change? |
It goes up |
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In the SAE crankcase viscosity classification 0W-30, what does the W stand for? |
Winter |
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Of the following motor oils, which oil is best suited for cold start conditions? a) SAE 15W-50 b) SAE 40 c) SAE 20 d) SAE 0W-30 |
d) SAE 0W-30 |
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When a SAE 20 is blended with a SAE 40, will the resulted viscosity be closer to SAE 30 or SAE 60? |
SAE 30 |
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Name four possible benefits of using synthetic base oil as a lubricant. |
1. Better thermal stability 2. High VI 3. Lower pour point 4. Natural detergency (some cases) 5. Fire resistance (some cases) |
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Name the synthetic base oil that is widely used as crankcase oil and is mixable with mineral oil. |
Polyalphaolefin (PAO) |
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Name three fluids that are used as fire-resistant hydraulic fluids. |
Phosphate ester Water glycol Oil-water emulsions |
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What types of synthetics are at risk for water-induced degradation called hydrolysis? |
Esters such as: Phosphate ester Polyol ester Dibasic acid ester |
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What is a common cause of seal swell or seal shrinkage? |
Incompatibility with base oils and/or additives. |
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What does ASTM stand for? |
American Society for Testing and Materials |
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Which of the following would be considered a white oil? Group III Hydrocracked Mineral Oil or Group IV |
Both |
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Which of the following would have the highest VI? a) PAO b) Hydrocracked mineral oil c) Solvent refined paraffinic d) Phosphate ester |
a) PAO |
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A mineral base oil that has a lot of aromatics and sulfur is less prone to oxidation. True or False? |
False |
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Name four impurities of mineral oils that are removed in the refining process. |
Salt Wax Aromatics Sulfur compound Solids Water |
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What concentration of additives might be found in typical diesel engine crankcase oil? |
10 to 30% |
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Name three types of polar additives. |
Dispersants Detergents AW additives EP additives Rust inhibitors |
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What types of solid contaminants might you find in a used diesel crankcase oil? |
Dirt and airborne dust Engine wear debris Rust Fuel soot Manufacturing or rebuild debris Failed filter debris |
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Name three types of antioxidants |
Hindered phenols Aromatic amines ZDDP |
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Name common causes of lubricant oxidation. |
High temperature Water oil aeration Metal catalysts (i.e. wear debris) |
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What are common indications of oil oxidation that are observed with the human senses? |
Sludge/varnish formation, oil darkening, acids and putrid oil odor |
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How does oxidized oil affect machine reliability? |
Causes corrosive wear, oil flow is hampered b y varnish and sludge, filters plug, increased viscosity causes heat build-up and oil flow problems |
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Which test can be used to assess the depletion of antioxidant additives? |
Remaining Useful Life Evaluation Routine (RULER) others: Rotating Pressure Vessel Oxidation test, FTIR, DSC, Cyclic Voltametry, elemental spectroscopy (ZDDP) |
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What is the role of a rust inhibitor? |
To produce a barrier film on oil-wet ferrous surfaces to repel water. |
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Name four lubricant types that are typically formulated with rust inhibitors. |
All lubricants except for some synthetics (phosphate esters for instance) are formulated with rust inhibitors. |
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Name a common lubricant that uses a detergent additive. |
Motor oils, also some compressor oils, paper machine oils, and gas engine oils |
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What are the two functions of a crankcase oil detergent additive? |
Neutralize acids and control deposits |
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Name the additive that is polar, envelopes soot, and keeps it finely divided. |
Dispersant |
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Name common causes of loss of dispersancy in motor oil. |
Coolant contamination, overextended oil drain, water contamination, high blowby, long idling, high elevation, exhaust gas recirculation |
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What are the consequences of a loss of dispersancy? |
Engine deposits Sludge Impaired lubrication Oil flow |
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What is the name of the additive that is primarily designed to control rust? |
Rust inhibitor |
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What is a common additive found in SAE 0W-30 motor oil but not found in SAE 30 motor oil? |
VI Improver |
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In the case of an oil that has operated for an extended period of time with depleted antioxidant additives, how might the properties of that oil change? |
Viscosity increase AN increase Darker color Putrid oil odor The oil will oxidize |
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Name the additive that specifically reduces and oil's tendency to fail to flow at cold start-up temperatures. |
Pour point depressant |
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Name a common polymer used as an antifoam agent. |
Silicone |
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What properties are provided by the additive ZDDP? |
Antiwear and antioxidation |
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Which two metals are often seen on oil analysis reports that come from the additive ZDDP? |
Zinc & Phosphorous |
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Name a common EP additive that is soluble in oil. |
Sulfur phosphorous |
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Name four solid lubricants found in some gear oils and greases. |
Molybdenum disulfide Graphite PTFE Borate |
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What type of additive is known to polish gear teeth? |
Sulfur-phosphorous EP additives |
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Which of these two additives is commonly found in hydraulic fluids: AW or EP? |
AW |
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Name two additives commonly found in turbine oil. |
Antioxidants and rust inhibitors Also, demulsifying agents, foam inhibitors |
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Describe three common ways additives can physically or chemically decompose in service. |
oxidation hydrolysis thermal degradation shear down |
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Describe three common ways the mass of an additive can be lost from oil during service. |
adsorption water washing filtration gravity separation evaporation particle stripping |
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Larger (heavier) oil molecules are associated with high or low viscosity? |
High |
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Kinematic viscosity is measured using a capillary gravity flow viscometer or a rotating spindle viscometer? |
a capillary viscometer |
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What property of oil measures an oil's internal resistance to flow and shear? |
Absolute (or dynamic) viscosity |
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When oil is momentarily heated, how will its viscosity change? |
go down |
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How can heat permanently increase oil's viscosity? |
Evaporation losses, oxidation |
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How can heat permanently reduce oil's viscosity? |
Cracking |
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Name three contaminants that can reduce oil viscosity. |
Fuel, solvents, refrigerant |
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What effect does emulsified water have on an oil's viscosity? |
Increases it |
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How does soot in diesel engine oil affect oil viscosity? |
Increases it |
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How does glycol contamination affect oil viscosity? |
Increases it |
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What is the ISO viscosity grade that sequentially follows ISO VG 320? |
ISO VG 460 |
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What percentage increase in viscosity does each ISO grade have over the one just below? |
50% |
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The viscosity designated by 80W-140 is associated with crankcase oils or driveline gear oils? |
Gear oils |
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An oil with a viscosity index of 135 is likely a VI improved mineral oil or a straight grade oil? |
VI improved |
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A base number will typically increase or decrease as the oil ages? |
Decrease |
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Flash point increases or decreases as oil viscosity increases? |
Increases |
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The specific gravity and API gravity relate to the density of oils. For water, what are the specific gravity and API gravity? |
1 and 10 |
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An oil with a specific gravity of 0.86 will float or settle when mixed with water? |
Float |
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What are two ways a seal may change when in contact with incompatible oil? |
Swell or shrink |
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What does NLGI stand for? |
National Lubricating Grease Institute |
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Which grease consistency is more like peanut butter? a. NLGI b. 000 c. Two d. Five |
c. Two |
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The dropping point of grease needs to be higher or lower when high operating temperatures are expected? |
Higher |
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Name a grease thickener that is commonly used for multipurpose greases. |
Lithium (12-hydroxy or complex) |
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What might happen when two incompatible greases are mixed? |
Reduction or increase in consistency (typically reduction) |
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Name four common soap-based thickeners used in greases. |
Lithium Calcium Sodium Aluminum |
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Which type of grease thickener is more resistant to high temperature? a) Simple soap b) 12-hydroxy soap c) Complex soap |
c) Complex soap |
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The amount of thickener in grease is typically more or less than the oil? |
Less |
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Name two problems associated with grease contaminated or exposed to water. |
Water Washing Water Absorption |
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What does bleed mean with respect to grease? |
When oil drains out of the thickener by gravity or centrifugal forces. |
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Which is more commonly used to lubricate motor bearings-grease or oil? |
grease |
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Which is more commonly used for high-speed rolling element bearing - grease or oil? |
oil |
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What is the name of the wear mode associated with scratch marking from particle contamination? |
Abrasive wear |
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What type of wear in gears and bearings is controlled by using EP (anti-scuff) additives? |
Adhesive wear |
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What type of wear might be caused by air bubbles or water vapor bubbles in a hydraulic fluid? |
cavitation |
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Name two types of wear commonly associated with sliding contact. |
Abrasive and adhesive wear |
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Name a common rolling contact wear mode. |
Contact fatigue, surface fatigue |
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Where on a gear tooth might you see pitting? |
Pitch line or rolling contact zones |
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Hydrodynamic lubrication produces greater oil film thickness than EHD. True or False? |
True |
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Boundary lubrication occurs in high-speed, low-load frictional contacts or the opposite? |
Opposite |
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Name three examples of total loss lubricant delivery methods. |
oil mist drop wick feed grease gun spray airborne oilers hand lubrication |
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In oil bath lubricated rolling-element bearings, what is the generally recommended oil level? |
Halfway up to the lowest roller or bail |
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In splash lubricated gearing, what is the generally recommended oil level? |
Oil should completely cover the lowest gear tooth. |
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Describe the mechanism of lubrication of a ring oiler. |
A metal ring rides a rotating shaft. As the ring rotates, oil is lifted by the ring and runs into the bearing grooves to provide lubrication. |
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What is a dry sump? |
A sump in which an oil level is not maintained. Instead, the oil discharges from bearings or gears drain out into a lower reservoir. |
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Which system recirculate the lubricant? Centralized lubrication systems or Total loss systems |
Neither |
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Is purge mist lubrication a wet sump or dry sump configuration? |
Wet sump |
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Single-point lubricators are typically used with grease or oil? |
Grease |
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What common manual lubrication device does a single-point lubricator replace? |
Grease gun |
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How much pressure can a grease gun generate? |
up to 15,000 psi |
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Injectors are used to regulate grease flow into bearings as a part of what type of lubricant application system? |
Centralized lubrication system |
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Reclassifiers are used with what type of lubrication system? |
Oil mist |
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Constant level oilers are used with wet sump or dry sump systems? |
Wet sump |
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The oil delivery rate is monitoring in what way with a drip oiler? |
Number of drop per minute. |
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Single-line parallel and single-line progressive are which category type of lubrication systems? |
Centralized |
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When an injector fails in a single-line progressive system, what happens to the other injectors? |
They also fail |
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What inspection needs to be performed when draining oil from a sump or reservoir? |
The presence of bottom sediment and sludge |
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Name four application for a filter cart. |
Flushing, oil add, oil drain, and kidney-loop filtration |
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Large circulating systems are more suitable for condition-based or scheduled (interval-based) oil changes? |
Condition-based |
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What oil conditions are monitored when doing a condition-based oil change? |
Physical and chemical oil properties (for example, oxidation stability, viscosity, acid number) and contamination |
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What is the oil consumption ratio? |
The total amount of oil purchased in a year divided by the total amount of oil a group of machines hold |
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What problems can occur when a bearing is lubricated with too much oil or grease? |
Higher energy consumption with oil/grease operating temperature, short lubricant life, thinning oil film thickness |
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A hydraulic fitting and button head fitting are used to introduce what type of lubricant and by what application method? |
Grease using a grease gun |
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Name two methods which protect grease fittings from the accidental ingress of contamination. |
1. Grease fitting caps 2. Leaving a dab of grease on the fitting after lubrication, which is wiped off prior to the next relubrication |
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What type of hydraulic component is sensitive to failure by silt lock? |
Electrohydraulic valves (for example, servo valves) |
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Environmental particle contaminants are typically harder or softer than machine surfaces? |
Harder |
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Name three types of wear that can be caused by particle contamination. |
Abrasion, surface fatigue, erosion |
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What does this symbol mean: µm ? |
micron or micrometer |
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10 percent equates to how many parts per million (ppm) ? |
100,000 ppm |
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How many microns are in a millimeter? How many microns are in one thousands of and inch? |
1000, 25 |
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What is the name of the instrument used to count and size particles automatically? |
Automatic particle counter |
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An oil that is an ISO 18/16/13 is approximately how much dirtier than an ISO 17/15/12? |
Twice |
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Large particles always cause more wear than small particles. True or False? |
False |
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The best way to control particle contamination is to remove particles as fast as they come in. True or False? |
False. The best way is to prevent their entry. |
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What are the three major sources or particle contamination? |
Built-in, ingestion, generated |
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Name five functions of a lubricant. |
1. Reduce wear. 2. Reduce friction. 3. Prevent corrosion. 4. Control contamination. 5. Control heat. |
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Slow speeds, high loads, shock loads, machine stops/starts can all case what form of lubrication? |
Boundary lubrication |
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Define how the beta rating is calculated. |
The number of particles larger than the given size before the filter divided by the number of particles larger than the same size downstream of the filter |
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When water contamination in oil is below its saturation point, the water is in what state? |
Dissolved |
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If a plant's lubricant consumption ratio drops by 25% what amount of reduced lubricant purchases occurred? |
25% |
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Do centrifugal separators work better for low or high viscosity oils? |
Low |
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If rust is suddenly appearing on oil wet machine surfaces, what tests should be performed on the oil? |
Water test, AN, rust inhibiting test (ASTM D665) |
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If you want oil or a machine to last twice as long, what maintenance strategy might you deploy? |
Proactive maintenance |
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Silt-size particles are typically in what size range? |
1 to 10 microns |
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Which is more sensitive to silt-size particles? Journal bearings or rolling element bearings? |
Rolling element |
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In diesel engines and other outdoor machines, wear metals such as iron, usually correlate to what common element found in dirt? |
Silicon (silica) |
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Name the composition of two common types of filter media. |
Glass fiber and cellulose |
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What three particle size ranges are used with the ISO code? |
4,6, and 14 microns |
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Typically, what percent of the pump's flow will go through a bypass filter on a diesel engine? |
10% |
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What types of contaminants might a centrifugal separator remove? |
Water, sludge, dirt, sediment, wear debris |
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What types of contaminants might a vacuum dehydrator remove? |
Water, entrained air, refrigerant, entrained gases |
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Why does an air compressor oil need good oxidation resistance? |
High temperatures, compressed air (oxygen), moisture |
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Which does more harm to the oil, its additives and oil-wetted machine surfaces: dissolved or emulsified water? |
Emulsified |
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What internationally recognized body defined classes of automotive chassis and wheel bearing grease? |
National Lubricating Grease Institute (NLGI) |
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What is generally defined as "a solid-to-semifluid product of dispersion of a thickening agent in a liquid lubricant"? |
Grease |
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Which internationally recognized body defines the consistency (hardness) of grease, based on a standard ASTM cone penetration test? |
National Lubricating Grease Institute (NLGI) |
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What are the principal thickeners used in grease manufacture? |
Soaps of lithium, sodium, calcium, barium and aluminum. Organo-clay is used in some high-temperature nonmelting greaes. Polyurea is often used in motor-bearing applications. |
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What is the "dropping point" of a grease? |
The temperature at which the first drop of liquid separates from the grease when heated under prescribed conditions |
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Is the dropping point of a grease a guide to maximum usable temperature? |
No. There are many other factors to be taken into account when determining maximum operating temperature of a grease. |
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What do the letters "EP" stand for? |
Extreme Pressure Usually a chemical compound added to the lubricant or grease to deal with heavily loaded conditions. |
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Name one property of grease that is improved through "complexing". |
Dropping Point. This is at least 100F (56C) higher than the dropping point of the corresponding simple soap grease. Complex greases are usable to higher temperatures. |
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How is the consistency or penetration of grease defined? |
It is the depth, in tenths of a millimeter, to which a standard cone sinks into the grease sample under prescribed conditions (ASTM D217) |
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What is the difference between oil viscosity and grease apparent viscosity? |
Apparent viscosity of grease varies with temperature and shear rate; viscosity of oil varies with temperature alone. |
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Grease penetration is commonly measured under two different conditions. What are they? |
Worked and unworked. Worked penetration is more significant to service behavior than unworked penetration. |
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Is oil separation or 'bleeding" in a grease reason to condemn it as unfit for service? |
No. A small amount of visible separated oil is normal and part of the lubrication mechanism. |
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Does storage temperature influence oil separation or bleeding in grease? |
Yes, separation or bleeding will generally increase with increasing temperature |
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Name a common effect of storage on grease. |
Hardening. This is not a permanent condition and simple stirring could soften it back into range. |
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Why is oxidation stability so important in grease? |
Grease cannot circulate and carry heat away from a lubrication point. |
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What properties are important in grease? |
Consistency, structural stability, load-carrying ability, dropping point, oxidation stability, rust and corrosion protection, water resistance, flow characteristics |
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Name three components of grease that contribute to its properties and in-service performance. |
The fluid, the thickener, and the additives. |
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Name three tests for evaluating load-carrying capability of grease. |
Four Ball Wear Test (ASTM D2266) Four Ball EP Test (ASTM D2596) Tinken OK Load (ASTM D2509) |
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Name two NLGI categories of automotive service greases. |
L for chassis and G for wheel bearings. The current categories of service are LB and GC. |
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In what respect is chassis grease different to wheel bearing grease? |
Chassis grease generally has a lower dropping point (150C vs. 220C), lower oxidation resistance, and leakage tendency. |
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How would you recognize a symptom of incompatibility of different greases? |
Commonly, incompatibility occurs when a mixture of two greases has a consistency markedly softer than either of the original greases. |
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Name two symptoms of incompatibility in greases. |
Lower heat resistance, decrease in shear stability, change in consistency. |
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How would the consistency of grease change with change in temperature. |
The penetration test is done at 25C. If temperature is reduced to 0C, grease will be firmer by one to two NLGI numbers. |
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Name two types of "non-soap" grease intended for high-temperature use. |
Polyurea grease and Organo-clay grease. |
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When would you consider using grease instead of oil as lubricant? |
Decrease frequency of lubrication, seal out contaminants, seal out contaminants, intermittent operation, to suspend solid lubricants, shock loading, low speed/high load |
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What lubrication conditions would you expect to find if roller bearings are running at higher-than-normal temperature? |
Overgreasing, lubricant starvation, using wrong grease |
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What lubrication failure conditions would you expect to find with tooth-breakage in a gearbox? |
None, this condition is not usually lubricant-related. |
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What lubrication condition would you expect to find in a malfunctioning electric motor running at high temperature? |
Excessive grease leakage into the motor windings, possibly through overgreasing |
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How long should grease be stored on-site? |
A common rule is any grease more than a year old should be inspected before its used. Sensitive greases should be inspected after six months. |
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Is it good practice to store grease containers out-of-doors? |
No, grease containers should not be stored outside. Store only under cover sheltered from elements. |
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Many equipment manufacturers specify relubrication as "x shots of grease". How much is a shot of grease? |
A shot is generally accepted to mean one stroke of a grease gun. However, grease guns deliver widely varying amounts of grease - typically 0.1 ounce or 2-3 grams. Always calibrate grease guns. |
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If someone handling lubricants on a regular basis developed a skin condition, how would you deal with it? |
Consult the Material Safety Data Sheets (MSDS) applicable to the products used and seek medical assistance if required. |
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How are users of lubricants containing potentially hazardous components notified of any danger? |
Hazard information must be communicated to customers and employees by means of container labeling, other forms of warning, MSDS and employee training. The requirement is law in many countries. |
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What does the abbreviation "MSDS" stand for? |
Material Safety Data Sheet |
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In lubrication terms what is the "Right Principle"? |
The right lubrication in the right place at the right time and right amount with the right attitude. |
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It is often stated that the cost of wear is two-thirds of the cost of energy. True or False? |
True. It is estimated that between one-third and one-half of all energy produced is consumed by friction. |
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Lubrication is about minimizing friction but is all friction bad? |
No. Without friction we could not walk, drive our car, light a match, nail wood together, etc. |
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When two surfaces are separated by a lubricant what friction, if any, remains? |
Fluid or internal friction remains. It is a measure of the fluid's resistance to flow. (Viscosity) |
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When a full film of lubricant exists between mating surfaces, what is this condition called? |
Hydrodynamic lubrication |
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What is the term used to define the measure of a fluid's internal resistance to flow? |
Viscosity |
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If an automotive engine or gear oil is designed to meet only one SAE viscosity limit, what is it commonly called? |
Single or monograde, for example, SAE 30, SAE 40, etc. |
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If an automotive engine or gear oil is designed to meet more than one SAE viscosity limit, what is it commonly called? |
Multigrade, for example, SAE 10W-40, SAE 15W-40, SAE 5W-50, etc. |
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What mineral oil has the higher natural viscosity index, paraffinic or naphthenic? |
Paraffinic |
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Mineral oils cannot have a viscosity index higher than 100. True or False? |
False. Highly refined mineral oils may have a VI as high as 130. |
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What properties of oil are used to calculate Viscosity Index? |
Viscosity Index is calculated from an oil's kinematic viscosity at both 40 degrees C and 100 degrees C. |
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Compared to an oil with a VI equal to 100, if an oil has a viscosity index of 0, how will its viscosity change with temperature? |
Such oil viscosity would change more rapidly with changes in temperature, compared to an oil with VI equal to 100. |
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If a mineral oil has a viscosity index of 100, will the base oil come from paraffinic or naphthenic crude oils? |
Paraffinic |
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Theoretically, high viscosity index oils are needed only under what conditions? |
High VI oils are generally required where machines are likely to operate over a wide range of temperatures, such as outdoors. |
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Abbreviations VHVI and UHVI are often used in connection with lubricating oils. What do they mean? |
VHVI = very high viscosity index, such as 130. UHVI = ultra-high viscosity index, such as 150. |
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The term "Viscosity Index Improver" (or VII) is often used in connection with lubricating oils. What does that mean? |
Viscosity index can be improved by dissolving a polymeric material in the oil. Multigrade oils generally contain this. |
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What causes darkening of oil in nonengine applications? |
Thermal or oxidative degradation causes discoloration and change in viscosity. Photocatalytic reaction from sunlight can cause darkening as well. |
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Oils are often quoted as having a "Pour Point". What is this? |
Pour point is lowest temperature at which a liquid lubricant will flow. This is useful when considering lubrication under conditions of low temperature or refrigeration applications. |
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Apart from chemical breakdown, oils may deteriorate in service. Why? |
Through contamination from external sources. Possible contaminants include: water, unburnt fuel in an engine, wear debris, atmospheric dust, soot from poor combustion, corrosion products, process materials, additive breakdown products. |
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What would be some of the reasons for replacing mineral oils? |
Temperature too high for mineral oil, temperature too low for mineral oil, lower flammability required for hazardous conditions, compatibility problems, and contamination problems. |
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Oil dispersed in water is called? |
An Emulsion |
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Water dispersed in oil is called? |
Invert emulsion |
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Viscosity can be measured in a number of different ways. Name three of them. |
Kinematic viscosity Dynamic viscosity Redwood viscosity Saybolt viscosity Engler viscosity |
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In selecting lubricating oil for a particular application, what stages would normally be followed? |
Selection of base oil, choose oil viscosity, define boundary lubrication requirements, other required properties and additives. |
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What would be the normal viscosity range for an engine oil at operating temperature? |
10 to 50 centistokes at normal operating temperature |
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What would be the normal viscosity range for hydraulic oil at operating temperature? |
20 to 100 centistokes at normal operating temperature |
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What would be the normal viscosity range for roller bearing oil at operating temperature? |
10 to 300 centistokes at normal operating temperature. |
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What factor influence the choice of viscosity? |
Speed (rpm), load, open or closed, oil feed, bearing size. |
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The two most frequent reasons for using nonmineral oils are? |
For higher temperatures and for fire resistance. |
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One of the most important properties of a metal working oil is not lubrication but? |
Cooling. The water in soluble oil provides this. |
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What would be a possible cause of "bad smell" in a soluble metal working oil? |
Microbial attack by bacteria and fungi. Adding biocides to fluids can combat these. |
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There are strong reasons for reducing (rationalizing) the number of lubricants being used in plant. Name three. |
Purchasing and storage problems can be reduced, a smaller variety of oils can be bought in larger quantities at a better price, less risk of misapplication. |
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Positive oil supply systems provide a number of benefits in machinery lubrication. Name three. |
Purchasing and storage problems can be reduced, a smaller variety of oils can be bought in larger quantities at a better price, less risk of misapplication. |
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Why is manual lubrication sometimes not effective? |
Dependent on operator/lube tech for success. Unless one is very careful, it is easy to miss lubrication points. |
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Total loss lubricating systems are not considered environmentally friendly. Why? |
Total loss is wasteful and leads to general oiliness of surrounding areas. |
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What would be the optimum oil level in a worm gearbox with the worm located below the wheel? |
Worm half immersed in oil. |
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What would be the optimum oil level in a worm gearbox with the worm located above the wheel? |
Wheel immersed between tooth depth and half diameter depending on speed. |
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What is the most destructive type of chemical reaction affecting oils in service? |
Oxidation |
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Name some of the products of oxidation. |
Acids, gums, varnish, sludge. |
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How is oxidation affected by wear metal particles? |
Wear metals act as catalysts and increase the speed of reaction. |
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Name two possible causes of viscosity loss. |
Fuel dilution in engine oils, top-up with lighter oil, permanent shear of viscosity index improver. |
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What are the main types of solid contaminant possible in an oil system? |
Wear debris, oil breakdown products (soot in engine) and external dust and dirt. |
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What liquid is a common contaminant in oil systems? |
Water and/or fuel |
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Name the three conditions that must be present in an oil system for microbiological contamination to occur. |
Source of carbon (in the oil). Source of bacteria (atmosphere). Source of free water. The correct temperature. The correct pH. |
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Does temperature influence microbial activity in oil? |
Temperature below 20 degrees C and above 40 degrees C will slow it down. Rapid growth occurs between these temperatures. |
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What would be a reason for changing oil type? |
Marked change in ambient or operating temperature, if oil deteriorates rapidly, excessive wear, risk of fire. |
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Are U-tube vents effective at controlling contamination? |
No, in fact they contribute to oil contamination. A better breather would contain a filter element and desiccant. |
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What factors would you consider when offered a "cheaper" oil? |
Is it cheaper through lower supply and transport costs? Is it less highly refined and/or contain less-effective additives? Are additives used compatible with those currently in use? |
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When would you consider flushing an oil system? |
When the oil being changed is heavily degraded or contaminated. |
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What is the best flushing oil to use? |
Generally the same oil that is to be used in the system, unless adherent surface deposits have formed, requiring the use of solvent or detergents. |
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Is it safe to enter very large oil reservoirs? |
Great care must be taken. There are established safety procedures for cleaning large systems; follow them |
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Is it acceptable practice to dispose of used oil in landfills? |
No. Used oil disposal is regulated in many countries and disposal or regeneration are generally available. |
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Can large volumes of used oil be "laundered" on-site? |
Generally yes; however, reuse will depend on the residual life of the additives and base oil. |
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Is it good practice to use antiseize compounds when assembling components? |
Unless specified by the OEM, avoid using it. Assembly torque will vary considerably causing failure of bolts. |
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What is the "Flash Point" of an oil? |
It is the lowest temperature at which the vapor above the liquid can be ignited by an open flame. |
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What a typical flash point for kerosene? |
Typically 50 degrees C but can vary slightly, depending on refinery. |
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What is a typical flash point for light hydraulic oil? |
180 degrees C to 220 degrees C |
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Name some of the health hazards associated with lubricants. |
Some toxicity, dermatitis, skin cancer, infection from microbial contamination. |
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Which of the following is not condition-based: Preventative, predictive or proactive maintenance? |
Preventative |
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What percentage of preventative maintenance expenditure is probably unnecessary? |
About 33% |
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How are maintenance costs paid for? |
Out of company profits. |
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Name the two main categories of equipment failure. |
Those related to maintenance practices and those related to outside influences. |
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Name one failure common to both categories of equipment failure. |
Lack of training. |
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Define "FRICTION". |
A resistance encountered when one body moves relative to another body with which it is in contact. |
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Define "TRIBOLOGY". |
The study of friction, lubrication and wear between moving surfaces. |
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There are three types of friction. What are they? |
Sliding friction, rolling friction, combination friction. |
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Provide examples of each type of friction. |
Piston in a cylinder (sliding), Ball and roller bearings (rolling), Gears (combination). |
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Name three lubricant film types separating moving parts. |
Full or hydrodynamic/hydrostatic film, Elastohydrodynamic film, Boundary layer film |
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Provide examples of the three lubricant film types. |
1. Shaft rotating at full speed (hydrodynamic). 2. Roller or ball bearing (elastohydrodynamic). 3. Load has squeezed lubricant out and metal-to-metal contact has occurred (boundary). |
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What would be the actual surface contact of two dry, newly machined surfaces? |
Around 5 to 10% of the apparent contact area. |
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What is the difference between extreme pressure and antiscuff additives? |
None |
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Name two disadvantages of using synthetic lubricants. |
Cost (typically 4 to 10 times more expensive) and compatibility with seals, hoses, coatings and other lubricants. |
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Define viscosity. |
Measure of the resistance to flow (or shear) of a fluid (internal friction). |
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What is considered to be the maximum viscosity limit for hydraulic vane pumps at startup temperature? |
860 centistokes |
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The viscosity of SAE 50 engine oil is similar to that of SAE 90 gear oil at the same temperature. True or False? |
True |
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The viscosity of SAE 90 gear oil is similar to that of ISO 220 oil at the same temperature. True or False? |
True |
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Define Viscosity Index. |
It is the rate of change in viscosity with respect to change in temperature. |
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The term "Demulsibility" is often used. In terms of lubricants, what does it mean? |
An oil's ability to separate from water. |
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What often happens if air is trapped in oil, and what would be the result? |
Foam. Oxidation increase, loss of bulk modulus. |
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What is "spanification"? |
A process where fat or fatty acid is reacted with an alkali to form a soap. Used to manufacture grease thickener. |
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What grease types would provide best water resistance? |
Barium and aluminum complex |
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What common grease thickener does not provide good water resistance? |
Sodium grease |
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What is considered to be the most commonly used grease? |
Lithium grease |
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Are lithium complex and aluminum complex greases considered to be compatible? |
No. They are incompatible. |
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What is a common use of polyurea greases? |
Electric motor bearings. |
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Can the pressure generated by an ordinary grease gun damage a bearing? |
Yes, manual grease guns can provide pressure to about 15,000 psi. Bearing seals can rarely withstand more than 500 psi. |
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What is ISO an abbreviation for? |
International Standards Organization |
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Can the old saying "if a little is good, a lot is even better" be applied to lubrications? |
No, too much lubricant can be as bad as not enough. |
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What is a common term for "Fluid Friction"? |
Viscosity |
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When greasing an antifriction bearing, is it good practice to completely fill the bearing housing? |
No, overlubrication will cause increased power consumption, and increase in bearing temperature and a reduction in bearing and grease life. |
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Name three factors affecting the amount of grease to be applied to a bearing. |
Is the bearing subjected to : shock loading, heat, water, speed, and external contamination. |
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Copper lubricant delivery lines are easy to install. Are there any problems associated with them? |
Copper lines are easy to crimp, work harden and have a catalytic effect on the lubricant oxidation. Steel piping is preferred. |
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Central lubrication systems are dirt tolerant? True or False? |
False. Cleanliness is essential. |
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If lubricant pumps requiring priming were installed, would you alert operators to this fact? |
Pumps requiring priming should be clearly identified to prevent operators from simply refilling when the reservoir has run dry. |
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What are the two wear metal detection methods employed in oil analysis? |
Ferrography (ferrous density analysis) and emission spectroscopy. |
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What is a major advantage of wear particle analysis? |
Most cost-effective method of monitoring incipient or impending machine failure from wear conditions. |
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Name five common elements that can be identified in spectrometric wear particle analysis. |
Iron, copper, lead, tin, aluminum |
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Name two DO's of lubricant storage. |
Keep containers tightly closed, store where leaks can be contained, note labeling for storage instructions. |
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Name two DON'T's of lubricant storage. |
Store drums and pails without protection from the elements, store drums on their ends, store near sparks or a heat source. |
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Filters are rated in microns. What is the limit of human visibility in microns? |
40 to 45 microns |
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What is the equivalent of one micron in inches? |
0.000039 inches |
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How many microns equal one-thousandth of an inch (0.001 inch)? |
25 |
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Can lubricant base stocks be used as received from the refinery? |
No, base oils as received from the refinery contain impurities that must be removed. |
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Are all crude oil types suitable for producing lubricant base stocks? |
No, many crude oil types do not produce satisfactory lubricant raw material and therefore many refineries use them to produce fuel and bitumen/asphalt only. |
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How many API base stock categories (groups) are there? |
There are five API groups I through V: Group I (solvent-refined) Group II (hydrotreated) Group III (hydrocracked) Group IV (polyalphaolefin) Group V (Esters and other not included above) |
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How many of the API base stock groups cover mineral oils? |
The first three. |
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What are some of the refinery steps employed to produce finished lubricant base stocks? |
Vacuum distillation, propane deasphalting, furfural extraction, dewaxing, hydroprocessing. |
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What is "hydroprocessing" in lubricating oil terms? |
Reacting the base oil with hydrogen and catalysts to remove/convert less desirable compounds of crude. |
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Additives are often "multi-functional". Name one such additive. |
Zinc dialkyldithiophosphate (ZDDP) is an effective antiwear, and oxidation inhibitor. A detergent is also multifunctional. It keeps surfaces clean and neutralizes acids. |
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Is the color of fresh lubricant significant to its performance? |
Not generally, except in the case of medicinal and "white" oils. However, change in color can be significant and may prompt action. |
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An oil's carbon-forming tendency is important in what application? |
Reciprocating air compressors, paper machine oils and other applications of high machine surface temperatures. |
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How does viscosity index improver work? |
In cold oil, the VII molecules adopt a coiled shape and have little effect on viscosity. In hot oil, the VII molecules uncoil and have a thickening effect. |
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How does "Thermal Stability" of a lubricant compare with oxidation? |
It is the ability of oil to resist degradation under high temperature conditions with minimal oxygen present. |
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Oils are often labeled "ATF", what does this stand for? |
Automatic Transmission Fluid |
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Oils labeled API GL4 or GL5 are often seen. What applications are they intended for? |
GL=Gear Lubricant, usually specified for automotive applications. API GL4 is often used in manual transmissions and GL5 in hypoid differentials. |
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How are engine oils evaluated for satisfactory performance? |
By testing in current production engines according to procedures and limits set by API, ASTM, SAE and other international standards bodies. |
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List three potential advantages of synthetic engine oils over mineral oils. |
High temperature stability, low temperature fluidity, high viscosity index, low volatility. |
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List three fluid qualities typically required by hydraulic systems. |
Correct viscosity, oxidation stability, antifoam and air separation, high viscosity index, wear protection, rust protection, machine compatibility. |
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What is "beta ratio" when referring to filters? |
A beta ratio is a means of representing a filter's capture efficiency. |
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What would a beta ratio of 75 mean for a 10-micron filter? |
Approximately 98.7% of particles larger than 10 microns will be removed. Restated: 74 our of every 75 particles larger than 10 microns will be removed by the filter. |
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Where would filters typically be placed in a hydraulic circuit? |
In the supply or pressure line and in the return line. |
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Do conventional filters remove water from oil? |
No. Special coalescing, desiccating or super absorbent filters are available for removing water. |
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If a hydraulic pump was making a high-pitched whine or rattling noise, what would you suspect? |
Cavitation. A condition caused by entrained air or water vapor in the lubricant and insufficient suction-line pressure. |
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Is it good practice to leave the hydraulic reservoir lid open to aid in cooling? |
No. This will allow contaminants to enter the system. |
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If high pressure were applied to a lubricant, what would be its effect on viscosity? |
Viscosity would increase |
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In plain bearings there are several mechanical factors affecting lubrication. Name three. |
Ratio of bearing length to diameter, clearance, surface finish, grooving, bearing material. |
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What is the purpose of grooves cut into a plain bearing surface? |
To distribute lubricant over the load-carrying surfaces. |
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Name two properties of plain bearing material. |
Scoring resistance and conformability |
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What is a "rolling element bearing"? |
A class of bearings where surfaces are separated by rollers, balls or needles. |
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Name a major factor in determining the correct oil viscosity for a rolling element bearing. |
Bearing speed factor (also known as DN factor) where rotational speed (RPM) is multiplied by pitch diameter in millimeters. |
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How is "stick-slip" overcome in machine tools? |
Use a lubricant containing special friction modifiers as typically found in way oils. |
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Meshing gears can be difficult to lubricate effectively. Why? |
The combination of rolling and sliding friction at meshing plus high loads and low speeds means they may need special additives to reduce wear. |
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Hypoid gears usually require special lubricants meeting GL5. Why? |
In addition to the usual rolling action, hypoid gears have a combination of radial and sideways sliding action in the boundary lubrication regime, similar to those found in worm gears. |
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What factors are considered when selecting enclosed gear lubricants? |
Gear type, gear speed, reduction ratio, transmitted power, operating temperature, load characteristics, drive type, application method. |
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What internationally recognized body publishes specifications for open gear lubrication, among others? |
American Gear Manufacturers Association (AGMA) |
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Name two possible causes of noisy open gear operation. |
Misalignment, compacted lubricant in tooth root area, excessive tooth wear. |
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High-speed couplings usually require special lubricating grease. Why? |
Centrifugal forces can cause oil and thickener to separate, allowing oil to leak away from frictional surfaces. |
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Name two disadvantages of manual oiling and greasing. |
There is usually an oversupply and excessive leakage or throw-off occurs. The machine often has to be stopped resulting in lost production. |
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An engine oil labeled "For API Service SL" is intended for what type of engine? |
According to the API Engine Oil Service Category Chart, SL indicates service for all automotive engines presently in use. Introduced in July 2001. |
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An engine oil labeled "For API Service SJ" is intended for what type of engine? |
According to the API Engine Oil Service Category Chart, SJ indicates service for 2001 and older automotive engines. Introduced in 1996. |
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How are diesel engine oils' performance levels labeled? |
API "C" Category covers diesel engines and is taken to mean Commercial or Compression Ignition. API CI-4 is a current (2002) classification for low-emission engines. |
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Passenger car lubricants are often said to meet "ILSAC Performance Specifications". What is ILSAC? |
The International Lubricant Standardization and Approval Committee (ILSAC) together with auto builders created the GF (gasoline fueled) series for passenger car engine oils. |
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European engine builders use ACEA specifications when referring to lubricants. What applications are covered by ACEA? |
ACEA sequences replaced the CCMC specifications and currently covers 3 ranges: such as "A" sequence for gasoline petrol engines, "B" sequence for passenger car diesel and "E" for heavy-duty diesel. |
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Apart from overlubrication, what are other common causes of rolling element bearing failure? |
Faulty mounting practice, incorrect shaft and housing fit, defective seals, inadequate lubrication, misalignment, vibration, passage of electric current through the bearing. |
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List five Do's for rolling element bearings. |
1. Work with clean tools in clean surroundings. 2. Use clean solvents and flushing oils. 3. Lay bearings out on clean paper. 4. Keep wrapped in oil-proof paper when not in use. 5. Use clean, sealed grease for repacking. |
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List five Dont's for rolling element bearings. |
1. Don't work in dirty surroundings. 2. Don't use dirty tools. 3. Don't handle with wet or dirty hands. 4. Don't spin with compressed air. 5. Don't leave grease containers open. 6. Don't remove grease from new bearings. |
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What are the consequences of failure? |
Human suffering, economic loss, material waste and customer frustration and disillusionment. |
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List the failure classifications of a mechanical system. |
Catastrophic failure, precipitous failure, impending failure, incipient failure and conditional failure. |
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What are the factors responsible for early machine or system failures? |
Design defects, manufacturing defects, assembly and commissioning defects, operational defects. |
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What are the four maintenance strategies generally seen in industry? |
Breakdown, preventative, predictive, and proactive. |
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Define "breakdown" maintenance. |
Run-to-failure. Fix it after it's broken. |
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Define "predictive" maintenance. |
The routine monitoring of machine systems and lubricants to determine whether surface degradation or fault conditions are occurring. |
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Define "preventative" maintenance. |
A scheduled activity performed prior to breakdown, typically involving the replacement or inspection of components. |
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Why is "proactive" maintenance the preferred activity? |
Proactive maintenance is a pre-alert activity performed prior to system, material or performance damage and is taken to correct conditions that could lead to wear or failure. |
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Identify three root causes of failure. |
Wear, fluid, contamination, fluid temperature, fluid physical stability, fluid chemical stability, material distortion/alignment. |
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What are the most common wear modes in machinery? |
Abrasion 22 to 50% Surface fatigue 10 to 20% Adhesion 7 to 15% Corrosion 5 to 13% Fretting 5 to 13% Erosion 4 to 8% |
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Three-body abrasion in a machine can be reduced by? |
Reduce contamination level, reduce bearing load and/or increase oil viscosity. |
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What is a "contaminant"? |
Any amount of material (or energy) that constitutes a chemically reactive hazard or that mechanically impairs the proper functioning of the equipment and the performance of the system. |
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How do contaminants enter fluid systems? |
Through introduction via dirty components, assemblies and fluid and/or through environmental ingression and surface degradation in an active system. |
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Is water considered to be a contaminant in a lubrication system? |
Yes, water is often just as destructive to a mechanical system as particulate contamination. |
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What external factors can influence the accuracy of oil sample analysis? |
Cleanliness of sample container, dirty sampling hardware, machine not operating prior to sampling, variable sample locations, insufficient flushing, sampling after oil change, inconsistent sampling procedures, etc. |
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What international standard defines the procedure for sample container cleanliness? |
ISO 3722 |
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What factors of sample preparation can enhance the accuracy of analysis? |
Sample from machines under normal operating conditions, sample upstream of filters and downstream of machine components, flush sampling devices and bottles, sample at proper frequency. |
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What would be the best sample location on a return line? |
At a turbulent zone such as a bend or elbow. |
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Why is sampling from a return line better than sampling from the reservoir? |
Information in a tank sample is diluted, possibly by hundreds of gallons; a return line sample will identify active debris generation whereas tank samples will be historic information at best. |
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When would you consider taking an oil sample after a filter or separator? |
To confirm the filter or separator is working correctly. |
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If a return-line sample identified an abnormal condition, what would you do next? |
Sample from secondary points upstream to isolate the problem. |
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What sampling methods could be considered for pressurized oil lines? |
Portable high-pressure tap, ball valve sampling point, minimess taps sampling. |
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On a diesel engine, where would the best sample point be? |
On the pressure line before filter. |
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Why is drop-tube sampling not recommended for engines? |
Machine has to be shut down, tube's final point is difficult to control, tube may pick up contaminants on the way in. |
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What would be the best way to sample noncirculating systems such as gearboxes? |
Drain port tap with short inward extension. |
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What should the scheduled sampling interval for off-highway diesel engines be? |
150 to 250 operating hours. |
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The recommended sampling interval for a steam turbine is? |
500 operating hours |
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When would you consider adjusting sampling frequency? |
Sampling should be adjusted to consider machine criticality, environment severity, machine age, and oil age. |
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What information should accompany the sample to the laboratory? |
Machine ID, sample point, date sampled, running conditions, hours (or distance) since last sample, last fluid change, amount of top-up, last filter change, last major service or repair. |
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I've run out of sample bottles. Can I send a sample in a soft drink bottle? |
Please do not do that. The results will be meaningless. |
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What would be the reasons for performing oil analysis? |
To monitor fluid properties, to monitor contaminants and wear debris analysis. |
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Rapid increase in Acid Number might indicate what? |
Severe oxidation of the oil, additive depletion, addition of incorrect oil. |
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A Base Number would normally trend downward; a sudden increase would indicate what event? |
Oil had been recently changed or topped up, addition of high BN oil (such as marine engine oil). |
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FTIR is a rapid means to monitor a cumber of oil parameters simultaneously. What does FTIR stand for? |
Fourier Transform Infrared |
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Lubricant health can be monitored using FTIR. With FTIR, what parameters can be seen? |
Oxidation, nitration, sulphation, soot, water, glycol, fuel and some additives. |
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Ferrous Density Analysis is a useful monitoring tool. What does it tell us? |
It tells us about the population of ferromagnetic (iron and steel) particles >5 microns in the oil and can serve as a warning of impending failure. |
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When abnormal wear is detected by Ferrous Density Analysis, what is the next step? |
Localize the source of debris with secondary sampling, asses the wear rate, employ oil analysis and vibration analysis to identify the root cause. |
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What questions can be answered by Analytical Ferrography? |
Where in the machine has the wear originated, what caused it, how sever is it, can it be arrested? |
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RULER is a useful test for evaluating what oil condition? |
Remaining Useful Life Evaluation Routine. The test evaluates the amount of antioxidants in the sample compared to a new oil standard to give a percent life remaining. |
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What test approximates the amount of metals by element contained in an oil sample? |
Elemental spectroscopy, however large particles may not be detected (>5 microns). |
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Name an oil analysis test used for proactive maintenance. |
Particle counting and viscosity analysis, among others. |
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Name two alarm techniques. |
Proactive and predictive alarms |
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What oil analysis techniques are "predictive" alarms? |
Rate-of-change alarms (trending), statistical alarms. |
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Name the three classes of machinery failure. |
Early (or infant) failure, random failure (during normal service life), time-dependent failure (at expected end-of-life. |
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What would be a possible cause of early failure? |
Inadequate lubrication, material defects, poor workmanship, substandard maintenance. |
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Which maintenance strategy is condition-based and controls failure root causes? |
Proactive maintenance |
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What is the primary objective of reliability-centered maintenance (RCM)? |
To provide a systematic process to optimize machine reliability. |
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How can time-dependent failures be controlled? |
By equipment monitoring. TD failure modes will provide some indication of deterioration prior to failure. |
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Wear debris analysis and vibration analysis relate to what maintenance activity? |
Predictive maintenance |
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They are three methods used to determine elemental constituents in an oil. What are they? |
Atomic emission spectroscopy, atomic absorption spectroscopy and X-ray fluorescence spectroscopy. |
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Provide an example of an atomic emission spectrometer. |
Rotating Disc Electrode (RDE), Inductively Coupled Plasma (ICP) |
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What instrument would be used to measure levels of iron, tin, lead, and copper in an oil sample? |
An elemental spectrometer. |
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A number of methods are available for automatic particle counting. Name two of them. |
Laser and pore blockage. |
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What must an oil analysis program have to be effective? |
A plan. |
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What is fundamental to any oil analysis program? |
Obtaining quality and representative oil samples frequently. |
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Diesel fuels can contain large quantities of sulfur (>3%). Do engines operating on such fuels require special attention? |
Yes, sulfur in fuel will lead to increased production of acidic products in the lubricant. For this reason, base number needs regular monitoring. |
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Synthetic engine oils are recommended for high-temperature applications. Does this mean that they do not oxidize? |
Synthetics can be affected by oxidation in much the same way as mineral oils, the process is much slower. Ester-based synthetics can fail rapidly if the shelf life is exceeded. |
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What is the "Crackle Test"? |
The crackle test is a test where water is indicated by a sizzle when oil is placed on a hot plate at 325 degrees C. It will not detect dissolved water. |
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How damaging is fuel dilution in an engine? |
Fuel dilution can lead to much increased wear, component seizure, increased oxidation and the potential for fire. 10% fuel contamination can remove 27% of piston ring metal in 100 hours of operation. |
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What is the effect of glycol contamination in engine oil? |
Glycol reacts with lubricant base stock and additives to cause oil thickening, to accelerate oil oxidation and sludge formation. |
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What is cavitation in a diesel engine coolant system? |
Cavitation occurs in areas of high vibration and particularly in the water jacket around the cylinder liners. Air bubbles in the coolant implode against the cylinder liner removing material until a perforation results. |
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If silicon is found in an oil sample, where has it come from? |
Silicon is often used as an antifoam agent (methyl silicone) so the new oil level must be deducted from the used oil silicon level. Silicon is also the result of contamination by sand and dust. |
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Is it good practice to analyze new oil as part of a maintenance program? |
Yes. This will provide a "baseline" for comparing subsequent analysis results. |
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There are a number of tests to establish Base Number (BN). Do these tests provide comparable results? |
No. They all give different results for the same sample and are thus not to be compared. |
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Is odor a reliable indicator of oil condition? |
Yes, any change in odor from new oil should be investigated for cause. |
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What is the first step in developing an effective oil analysis program? |
Develop a business plan to establish the purpose and application, the benefits and impact on current practice. Expected costs, monitoring parameters and sample intervals need to be included. |
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Can it be assumed that lubricant deliveries by reputable companies will meet specification? |
Unfortunately no. Mistakes are made. Deliveries should always be inspected. |
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In lubrication terms, what is the "Clean" principle? |
Clean storage, clean hands, clean dispensing equipment, clean application practice. |
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What would be one way to minimize transferring contaminants from the drum to the machine? |
By using a filter cart to transfer oil. |
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If drums must be stored outside, what is the best way to do this? |
At the very least, drums should be stored on their sides with the bungs in the 9 and 3 oclock positions. |
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Is it good practice to use funnels for topping-up machines? |
Funnels are a source of contamination and should be avoided. If they must be used, then they should be cleaned before and after use. |
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What is the best type of reusable container for topping up oils? |
Use dedicated resealable containers for each oil type of family. |
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What is the effect of water contamination on rolling element bearing life? |
Bearings can lose 75% of their expected service life due to water at less than 0.1%, or before it becomes cloudy. |
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Name an effective on-site test for diesel engine crankcase oils. |
The Blotter Spot test is an effective field test to assess the presence of certain contaminants and oil properties. |
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What are the four steps to lubrication excellence? |
Define the lube audit and program design, team-wide on-site training, apply best practice, measure results. |
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