MDE 10 End of Unit Quiz

Correct Answer: B) Keeping the oil free from moisture

Explanation: Keeping the oil free from moisture is essential in preventing oxidation. Moisture can accelerate the oxidation process, leading to the formation of acids and sludge that degrade the oil's quality.

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: 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.

B) Forced circulation lubrication

Explanation: Forced circulation lubrication is a common method used in medium-speed diesel engines. This method uses a pump to circulate oil throughout the engine, ensuring a steady supply to the cylinder liners and other critical components. Splash lubrication is less common in medium-speed engines, which typically use forced circulation for better control and consistency.

Correct Answers: A) Add oil to the gearbox until it reaches the recommended level
D) Regularly check and maintain the oil level

Explanation:

• Add oil to the gearbox until it reaches the recommended level: Adding the appropriate amount of oil directly addresses the issue of insufficient oil level, ensuring proper lubrication and operation.
• Regularly check and maintain the oil level: Regular monitoring and maintenance prevent the oil level from dropping below the recommended amount, helping to avoid future problems.

Note: Installing a larger oil reservoir can be helpful but is not a direct solution to the immediate problem of insufficient oil. Decreasing the operational load or using a different type of lubricant does not address the core issue of the oil level being too low.

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.

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.

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.

Correct Answers: A) Improve ventilation or cooling systems around the gearbox
B) Use high-temperature resistant lubricants
D) Reduce the gearbox's operational speed

Explanation:

• Improve ventilation or cooling systems around the gearbox: Enhancing the ventilation or adding cooling systems can help manage and reduce the temperature around the gearbox.
• Use high-temperature resistant lubricants: Lubricants designed to withstand higher temperatures will perform better under elevated ambient temperatures and prevent overheating.
• Reduce the gearbox's operational speed: Operating the gearbox at a lower speed can reduce friction and heat generation, helping to manage the effects of high ambient temperatures.

Note: Increasing the ambient temperature control systems is not a practical solution since the problem is related to high ambient temperatures rather than controlling or increasing them. Insulating the gearbox would retain heat rather than alleviate the problem.

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 Answer: B) Ensuring proper filtration and regular filter changes

Explanation: Proper filtration and regular filter changes help to remove contaminants that can lead to sludge and deposits in the oil, keeping the oil clean and in good condition.

Correct Answer: B) Metallic particles

Explanation: Metallic particles can enter the lubricating oil as a result of wear and tear of engine components such as bearings, gears, and other moving parts. These particles can cause abrasion and increase engine wear.