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
An electric motor bearing is running hotter than normal and emitting a grinding noise. After inspection, you find the grease has become dry and crumbly. What has most likely occurred?
Answer: The base oil has bled out of the thickener, leaving behind a dried soap structure
When grease ages or overheats, the base oil separates (bleeds) from the thickener, leaving a dry soap structure that no longer lubricates.
What does a low 'demulsibility' rating indicate about an oil?
Answer: The oil has difficulty separating from water once mixed
Demulsibility measures an oil's ability to shed water; poor demulsibility means the oil and water form a stable emulsion that is difficult to separate.
Which lubrication regime is present when the lubricant film completely separates two surfaces and load is fully supported by fluid pressure?
Answer: Hydrodynamic (full-film) lubrication
Hydrodynamic lubrication occurs when a continuous pressurized fluid film fully separates the surfaces, resulting in very low friction and wear.
What is 'over-greasing' a bearing likely to cause?
Answer: Elevated operating temperature due to grease churning and increased resistance
Excess grease causes the rolling elements to churn through the grease, generating heat that can degrade the lubricant and damage the bearing.
In an oil mist lubrication system, what is the purpose of the 'reclassifier' fitting at the bearing?
Answer: To convert the dry mist into larger oil droplets that wet the bearing surfaces
A reclassifier fitting at the bearing point converts the fine dry mist into larger droplets ('wet mist') that actually deposit oil on the bearing surfaces.
Which type of oil additive is used to prevent rust on metal surfaces in the presence of water?
Answer: Corrosion inhibitor (rust inhibitor)
Rust or corrosion inhibitors adsorb onto metal surfaces to form a protective barrier that displaces water and prevents oxidative rust formation.
A technician notices that oil drained from a gearbox has a milky white appearance. What does this indicate?
Answer: Water has emulsified with the oil
A milky or cloudy appearance in oil indicates that water has entered and emulsified with the oil, which significantly reduces its lubrication effectiveness.