MDE 10 End of Unit Quiz

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.

Explanations:

1. A) Water: Correct. Water contamination can lead to rust and corrosion, affecting engine performance and durability.B) Sulfates: Incorrect. Sulfates are not typically identified from oil samples in standard analysis but are rather a byproduct of combustion.

   C) Silicon: Correct. Silicon usually indicates the presence of dust or dirt, which can cause abrasive wear.

   D) TBN: Incorrect. TBN is a measure of the oil's ability to neutralize acids, not a contaminant.

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) 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) Viscosity

Explanation: Viscosity is essential for preventing metal-to-metal contact because it determines the oil’s ability to maintain a lubricating film between moving parts. A proper viscosity ensures that the oil can form a thick enough film to prevent wear.

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.

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 Answers: A) Inadequate oil flow or circulation
B) Excessive friction due to worn or misaligned gears
C) High ambient temperature
E) Insufficient oil level

Explanation:

• Inadequate oil flow or circulation: Poor circulation can prevent effective cooling of the oil and gearbox components, leading to higher temperatures.
• Excessive friction due to worn or misaligned gears: Increased friction from worn or misaligned gears generates more heat, raising the oil temperature.
• High ambient temperature: An elevated ambient temperature can affect the gearbox's cooling efficiency, leading to higher oil temperatures.
• Insufficient oil level: Low oil levels can reduce the effectiveness of lubrication and cooling, causing the temperature to rise.

Note: While an overfilled oil reservoir and a faulty temperature sensor can affect gearbox performance, they are less direct causes of excessive oil temperature compared to the listed answers.

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) 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.

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.

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.