MDE 10 Q2

Explanation:

• A) Grease can become less effective at high temperatures compared to oil: Correct. Grease can degrade or become less effective at higher temperatures compared to oils, which often have higher temperature tolerances.
• B) Grease requires frequent re-lubrication compared to oil: Incorrect. One advantage of grease is that it generally requires less frequent re-lubrication compared to oil due to its thicker consistency and staying power.
• C) Grease can attract dust and debris, leading to potential contamination: Correct. Grease can attract dust and debris due to its sticky nature, which can lead to contamination of the bearing and reduced lubrication effectiveness.
• D) Grease provides less protection against corrosion compared to oil: Incorrect. Grease often provides good protection against corrosion due to its ability to stay in place and its additives.

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.

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.

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.

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.