Lubricant Selection & Management Flashcards
7 cards from real CLS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Lubricant Selection & Management flashcards as text
An ISO VG 46 hydraulic oil is mistakenly used in a system designed for ISO VG 68. What is the most likely immediate consequence?
Answer: Internal leakage past seals due to lower viscosity
Using a lower viscosity oil than specified increases internal leakage across pump and valve clearances, reducing volumetric efficiency and potentially causing overheating.
Which additive is primarily responsible for preventing rust in water-contaminated circulating oil systems?
Answer: Sodium sulfonate rust inhibitor
Sulfonates (like sodium or calcium sulfonates) adsorb on metal surfaces to form a protective film that displaces water and prevents rust formation.
A lubricant's Total Base Number (TBN) is used primarily to assess its:
Answer: Remaining alkaline reserve to neutralize acids
TBN measures the alkaline reserve remaining in the lubricant to neutralize acidic combustion by-products and oxidation acids.
Which factor most significantly increases the relubrication frequency for a grease-lubricated rolling element bearing?
Answer: All of the above
Elevated temperature, larger bearing size, vertical shaft orientation (grease migrates away), and higher speeds all increase grease degradation and loss rates, requiring more frequent relubrication.
When transitioning equipment from a mineral oil to a PAO synthetic lubricant, which preliminary step is most important?
Answer: Perform a system flush to remove mineral oil residues
Flushing removes residual mineral oil and varnish deposits that could contaminate the new synthetic and reduce its service life.
A plant engineer wants to reduce lubricant consumption on a slow-speed open chain drive. Which application method is most efficient?
Answer: Brush-applied chain lubricant with precise metering
Brush application allows precise placement of a heavy-bodied chain lubricant directly onto the chain's inner plates and pins, minimizing waste.
Which of the following best describes the function of a tackiness (adhesion) additive in a lubricant?
Answer: Causes oil molecules to stretch and resist fling-off from surfaces
Tackiness additives (typically high-molecular-weight polymers) increase the cohesion and adhesion of the oil film, preventing it from being flung off rotating or reciprocating surfaces.