MDE 10 End of Unit Quiz

Correct Answers: A) Presence of sludge in the oil
B) Unusual or foul odor from the oil
C) Increase in oil viscosity
D) Discoloration of the oil

Explanation: Microbial degradation of lubricating oil can cause the formation of sludge, an unpleasant odor, an increase in viscosity due to the by-products of microbial activity, and discoloration of the oil as it breaks down.

Correct Answer: A) The oil remains fluid and pumpable at low temperatures

Explanation: The pour point of an oil indicates the lowest temperature at which it remains fluid and can be pumped. A low pour point ensures that the oil can operate effectively even in cold conditions.

A) Fuel dilution: Incorrect. Silicon is not typically associated with fuel dilution.

B) Increased wear from abrasive particles: Correct. High silicon levels indicate the presence of abrasive particles, leading to wear.

C) Increased oil oxidation: Incorrect. Silicon is not directly related to oil oxidation.

D) Higher levels of water contamination: Incorrect. Silicon contamination is not related to water levels.

Correct Answer: A) Prolonged idling of the engine

Explanation: Prolonged idling can lead to incomplete combustion, allowing unburned fuel to enter the crankcase and mix with the lubricating oil, leading to fuel dilution.

Explanation:

• A) A lubrication method where a thick film of oil separates surfaces, minimizing friction and wear: Incorrect. This describes full-film lubrication, not boundary lubrication.
• B) A lubrication condition where the lubricant film is so thin that surfaces make intermittent contact, and additives in the oil help reduce wear: Correct. Boundary lubrication occurs when the lubricant film is very thin, allowing surfaces to make intermittent contact. Special additives in the lubricant help reduce wear and friction under these conditions.
• C) A technique where oil is constantly replenished by an external supply to ensure a continuous lubrication film: Incorrect. This describes a different lubrication method, not boundary lubrication.
• D) A system where oil is applied in a high-pressure spray to ensure effective lubrication of moving parts: Incorrect. This describes spray lubrication, not boundary lubrication.

Correct Answer: A) To ensure adequate cooling and prevent overheating of gearbox components

Explanation: Large quantities of lubricating oil in a gearbox are used primarily to ensure proper cooling and to prevent overheating of the gearbox components. The oil helps absorb and dissipate heat generated by the friction and mechanical work within the gearbox, maintaining operational efficiency and preventing damage.

Explanation:

• A) Increased oil consumption: Excessive lubrication often results in higher oil consumption because surplus oil can leak or be burned off, leading to a need for more frequent topping up.
• B) Reduced friction: This is misleading. While lubrication does reduce friction, excessive lubrication does not necessarily lead to reduced friction; it can cause other issues such as oil foaming.
• C) Increased risk of oil foaming: Excessive lubrication can lead to oil foaming, which decreases the effectiveness of lubrication and can cause engine damage due to poor oil film formation.
• D) Enhanced cooling: This is incorrect. Excessive oil does not necessarily enhance cooling and can actually lead to problems such as oil foaming, which impairs the cooling function.

Explanation:

• A) Reduces friction between moving parts: Correct. Lubricating oil forms a film between moving parts to reduce friction, which minimizes wear and improves engine efficiency.
• B) Acts as a coolant to lower engine temperatures: Correct. Lubricating oil helps to carry away heat from the engine components, contributing to overall engine cooling.
• C) Cleans the engine by removing contaminants: Correct. Lubricating oil helps to suspend and carry away contaminants such as dirt and metal particles, preventing them from accumulating in the engine.
• D) Enhances fuel combustion efficiency: Incorrect. While lubricating oil affects engine performance, it does not directly enhance fuel combustion efficiency.
• E) Seals gaps between engine components: Incorrect. Lubricating oil does not seal gaps; it primarily reduces friction, cleans, and helps in cooling.
• F) Prevents corrosion and rust on engine parts: Correct. Lubricating oil contains additives that help to protect engine parts from corrosion and rust.

Correct Answers: A) Replace worn or damaged gears
C) Adjust or realign misaligned gears

Explanation:

• Replace worn or damaged gears: Worn or damaged gears can increase friction and cause operational issues. Replacing them with new gears addresses the root cause of the excessive friction.
• Adjust or realign misaligned gears: Misaligned gears can cause excessive friction and wear. Correcting the alignment ensures smooth engagement and operation of the gears, reducing friction.

Note: Increasing the gearbox oil temperature and decreasing the oil level are not effective solutions for dealing with friction issues due to worn or misaligned gears. Using a different type of lubricant might help in some cases but does not address the underlying mechanical issues with the gears themselves.

Explanation:

• A) Increased friction and wear: Insufficient lubrication causes increased friction between moving parts, leading to overheating and accelerated wear, which can result in engine damage and failure.
• B) Improved engine efficiency: This is incorrect. Insufficient lubrication does not improve engine efficiency. Instead, it increases friction and reduces efficiency.
• C) Decreased oil consumption: This is incorrect. Insufficient lubrication typically leads to increased oil consumption due to the need for additional oil to manage the increased friction and wear.
• D) Enhanced engine performance: This is incorrect. Insufficient lubrication generally degrades engine performance by causing excessive friction, overheating, and potential damage.

Correct Answer: A) To prevent oil degradation and maintain performance over time

Explanation: High oxidation resistance helps prevent the oil from breaking down due to reactions with oxygen. This maintains the oil’s performance and prolongs its useful life, ensuring reliable engine protection.

These questions and answers cover essential properties of lubricating oil, highlighting their importance for engine performance and safety.

Correct Answer: B) Total Base Number (TBN)

Explanation: The Total Base Number (TBN) measures the oil’s ability to neutralize acidic byproducts from combustion. A higher TBN indicates better capacity to protect engine parts from acid corrosion.