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
What is the primary reason synthetic lubricants are preferred over mineral oils in extreme cold temperature applications?
Answer: Synthetic oils maintain lower viscosity at cold temperatures and have lower pour points
Synthetic lubricants are engineered to flow at much lower temperatures than mineral oils, ensuring proper lubrication during cold starts.
In a centralized automatic lubrication system, what is the role of the injector or metering valve?
Answer: To deliver a precise, measured amount of lubricant to each lubrication point per cycle
Injectors or metering valves in centralized systems dispense a fixed, pre-set volume of lubricant to each point during each pressurization cycle.
What is 'oxidation stability' in the context of lubricating oils?
Answer: The oil's ability to resist chemical breakdown when exposed to oxygen over time
Oxidation stability measures how well an oil resists reacting with oxygen, which causes thickening, varnish, sludge, and acid formation that shorten oil and equipment life.
A ball bearing has a recommended relubrication interval of 2,000 hours. The bearing is operating at twice the rated speed. How should the relubrication interval be adjusted?
Answer: Shorten the interval because higher speed degrades grease more rapidly
Higher operating speeds increase heat generation and mechanical working of the grease, accelerating degradation and requiring more frequent relubrication.
What is the correct procedure when switching a system from a mineral oil to a synthetic lubricant?
Answer: Drain the mineral oil, flush the system thoroughly, then fill with synthetic
Most synthetic lubricants are incompatible with mineral oils; the system must be fully drained and flushed to prevent the mixture from degrading both lubricants' performance.
Which bearing failure mode is directly associated with lubricant film breakdown due to metal-to-metal contact?
Answer: Adhesive wear (scuffing/scoring)
Adhesive wear (scuffing or scoring) occurs when the lubricant film fails and opposing metal surfaces weld and tear apart microscopically due to direct contact.
What does the 'four-ball wear test' evaluate in a lubricant?
Answer: The lubricant's ability to prevent wear and its load-carrying capacity
The four-ball wear test uses three stationary balls and one rotating ball under load to measure the lubricant's wear scar diameter and load-carrying (EP) performance.