CMRP Lubrication Management 1 — Questions and Answers
Question 1: What is the primary purpose of lubrication in rotating machinery?
- Increase equipment operating temperature
- Reduce friction and wear between moving surfaces (Correct answer)
- Eliminate the need for periodic inspections
- Increase the load capacity of structural components
Correct answer: Reduce friction and wear between moving surfaces
Lubrication reduces friction and wear between moving surfaces, extending equipment life and improving energy efficiency.
Question 2: Which lubrication delivery method distributes oil to bearings and gears by the action of rotating components contacting an oil sump?
- Forced pressure circulation
- Wick or pad lubrication
- Splash lubrication (Correct answer)
- Oil mist lubrication
Correct answer: Splash lubrication
Splash lubrication uses rotating components to pick up oil from a sump and fling it onto bearing surfaces through splashing action.
Question 3: A lubricant with a high Viscosity Index (VI) is preferred for equipment with wide temperature swings because it:
- Has a lower flash point for easier ignition
- Maintains relatively stable viscosity across a broad temperature range (Correct answer)
- Contains more anti-wear additives per unit volume
- Is suitable only for very low-speed applications
Correct answer: Maintains relatively stable viscosity across a broad temperature range
A high VI means viscosity changes less with temperature, ensuring adequate film thickness across the full operating temperature range.
Question 4: Before mixing lubricants from two different manufacturers or product lines, the best practice is to:
- Mix them freely since all mineral oils are compatible
- Verify compatibility through testing or manufacturer guidance (Correct answer)
- Always blend at a 50/50 ratio to dilute additives equally
- Add a universal additive package to neutralize differences
Correct answer: Verify compatibility through testing or manufacturer guidance
Incompatible lubricants can cause additive precipitation, sludge formation, or loss of protective properties, so compatibility must be confirmed before mixing.
Question 5: Which grading system is used to classify the consistency (firmness) of grease for bearing applications?
- SAE viscosity grade
- NLGI consistency grade (Correct answer)
- ISO VG classification
- AGMA gear oil grade
Correct answer: NLGI consistency grade
The NLGI (National Lubricating Grease Institute) consistency grade, ranging from 000 (fluid) to 6 (very stiff), specifies grease firmness for a given application.
Question 6: What is the primary cause of lubricant oxidation during service?
- Excessive cooling below the pour point
- Low operating pressure in the lubrication circuit
- Prolonged exposure to heat and oxygen (Correct answer)
- Absence of ferrous wear particles in the oil
Correct answer: Prolonged exposure to heat and oxygen
Heat and oxygen are the main drivers of oxidation, breaking down base oil molecules and depleting the additive package, which increases acid content and viscosity.
Question 7: Which oil sampling practice provides the most representative sample for condition monitoring analysis?
- Drain the sump completely and sample from the drain plug
- Draw a sample from a live zone in the system during normal operation (Correct answer)
- Sample fresh oil from the drum prior to filling
- Collect a sample after equipment has been shut down for 24 hours
Correct answer: Draw a sample from a live zone in the system during normal operation
Sampling from a live zone during normal operation captures suspended wear particles and contaminants that reflect true equipment condition, yielding the most actionable data.
CMRP Lubrication Management 1
What is the primary purpose of lubrication in rotating machinery?