MDE 10 End of Unit Quiz

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 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.

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.

B) Oil is splashed onto the cylinder liners by the movement of engine components

Explanation: In splash lubrication, oil is dispersed onto the cylinder liners by the movement of rotating engine components, such as the crankshaft. This method is generally used in smaller engines or older designs, and it relies on the mechanical action to spread oil, which may not be as uniform or controlled as forced circulation.

Correct Answer: C) Presence of water in the oil

Explanation: Microbial contamination often occurs when there is water present in the lubricating oil, as microbes thrive in the water-oil interface. This can lead to the formation of sludge and acids that degrade the oil and damage the engine.

B) Forced circulation lubrication

Explanation: Medium-speed diesel engines typically use forced circulation lubrication to ensure consistent oil delivery and effective cooling. This method is preferred over splash lubrication in these engines due to its ability to provide a more controlled and reliable oil supply.

Explanation:

• A) A method where oil is forced under pressure between surfaces to create a lubricating film, eliminating metal-to-metal contact: Correct. Hydrostatic lubrication involves the use of a pressurized oil film to create a separation between surfaces, preventing metal-to-metal contact and reducing friction.
• B) A system where oil is distributed by gravity flow to lubricate moving parts in an engine: Incorrect. This describes a gravity-fed lubrication system, not hydrostatic lubrication.
• C) A technique that uses a splash of oil from rotating components to lubricate engine parts: Incorrect. This describes splash lubrication, not hydrostatic lubrication.
• D) A lubrication method where oil is sprayed onto components to reduce friction and wear: Incorrect. This describes spray lubrication, not hydrostatic lubrication.

Correct Answer: C) It ensures adequate lubrication of engine components.

Explanation: Maintaining proper oil levels is critical for ensuring that all engine components receive adequate lubrication, reducing wear and tear and keeping the oil in a satisfactory condition.

A) Improves oil cleanliness by removing contaminants: Incorrect. Soot contributes to contamination rather than improving cleanliness.

B) Increases the risk of abrasive wear and reduces oil life: Correct. Soot can cause abrasive wear and degrade oil quality.

C) Enhances lubrication properties and reduces friction: Incorrect. Soot generally harms lubrication properties and increases friction.

D) Improves the oil's ability to protect against corrosion: Incorrect. Soot does not improve corrosion protection.

Correct Answer: C) Maintaining proper oil temperature

Explanation: Maintaining the proper oil temperature is crucial for ensuring that the lubricating oil remains in good condition. Proper temperature helps in reducing oxidation and ensures the oil's viscosity remains within the optimal range for effective lubrication.

Explanation:

• A) Grease provides continuous lubrication without the need for external oil supplies: Correct. Grease is thick and stays in place, providing continuous lubrication and reducing the need for frequent re-lubrication or external oil supplies.
• B) Grease reduces the friction between moving parts more effectively than oil: Incorrect. While grease is effective in reducing friction, it is not necessarily more effective than oil in all applications. Its main advantage is its ability to stay in place and reduce the need for frequent re-lubrication.
• C) Grease can be applied in higher temperatures compared to oil: Incorrect. Grease and oil have different temperature tolerances depending on their formulations, but grease is not universally better at higher temperatures compared to oil.
• D) Grease prevents corrosion better than oil due to its thicker consistency: Incorrect. While grease can offer some protection against corrosion, its primary advantage is its staying power and ability to provide continuous lubrication.

B) By a mechanical pump that circulates oil through the engine

Explanation: In forced circulation lubrication systems, a mechanical pump is used to circulate oil throughout the engine. This method ensures that oil reaches the cylinder liners and other critical areas consistently, which helps in maintaining proper lubrication and cooling.