Lubrication Flashcards
7 cards from real ITMC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Lubrication flashcards as text
Which condition describes 'false brinelling' in a bearing, and what lubrication-related practice helps prevent it?
Answer: Fretting wear in stationary bearings caused by vibration; prevented by using grease with corrosion inhibitors and anti-wear additives
False brinelling occurs when vibration causes micro-motion between rolling elements and raceways in stationary bearings, creating wear; protective grease with corrosion inhibitors helps mitigate this.
What is the significance of the 'total acid number' (TAN) in oil analysis?
Answer: It indicates the level of acidic degradation products formed from oil oxidation
TAN (Total Acid Number) increases as oil oxidizes and forms acidic byproducts; a rising TAN signals oil degradation and the potential for corrosive damage to metal surfaces.
A plant uses an ISO VG 68 hydraulic oil. In summer the system runs hot and performance suffers. Which action correctly addresses this using lubricant selection?
Answer: Switch to ISO VG 100 to maintain adequate film thickness at the higher operating temperature
At high temperatures, oil thins; switching to a higher ISO VG grade (e.g., VG 100) ensures the film remains thick enough to protect components at elevated operating temperatures.
When taking an oil sample for analysis from a hydraulic system, which sampling method provides the most representative sample?
Answer: Sampling from a live zone in the return line using a vacuum pump or minimess valve while the system is running
Sampling from a live zone in the return line while the system is running captures a representative, well-mixed sample that accurately reflects the oil and contamination condition.
What is the purpose of a 'base number' (BN or TBN) measurement in lubricating oil analysis?
Answer: It indicates the reserve alkalinity available to neutralize acids formed during operation
Total Base Number (TBN) measures the oil's remaining alkaline reserve, which neutralizes acidic combustion byproducts and oxidation products; a depleted TBN means the oil can no longer protect against acid corrosion.
Which factor most directly determines whether a plain (journal) bearing operates in the hydrodynamic lubrication regime?
Answer: The combination of shaft speed, oil viscosity, and applied load (Sommerfeld number)
Hydrodynamic film formation in journal bearings is governed by the Sommerfeld number, which combines shaft speed, oil viscosity, bearing geometry, and load to predict film thickness.
A technician is lubricating an open gear drive exposed to the environment. Which type of lubricant is most appropriate for this application?
Answer: Tacky, high-viscosity open gear compound that resists fling-off and protects against moisture and wear
Open gear compounds are formulated to be highly viscous, tacky, and adhesive to resist centrifugal fling-off, while providing heavy-duty EP protection and moisture resistance on exposed gear drives.