MDE 10 End of Unit Quiz

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.

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.

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.

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.

A) Increases oil viscosity and leads to foaming: Incorrect. Water typically reduces oil viscosity and can cause foaming.

B) Promotes corrosion and rust formation on engine components: Correct. Water contamination leads to rust and corrosion.

C) Enhances the oil’s cleaning and dispersant properties: Incorrect. Water does not enhance cleaning properties; it can harm them.

D) Improves the oil’s cooling capacity: Incorrect. Water does not improve oil cooling; it can cause damage.

A) Increases oil viscosity and reduces lubrication efficiency: Incorrect. Fuel dilution generally reduces oil viscosity and lubrication efficiency.

B) Reduces the oil’s ability to carry away heat: Incorrect. Fuel dilution affects lubrication and may not significantly impact heat dissipation.

C) Leads to increased oil consumption and potential for engine damage: Correct. Fuel dilution lowers the oil’s lubricating properties and can lead to increased oil consumption and engine wear.

D) Improves the oil’s cleaning ability: Incorrect. Fuel dilution actually reduces the oil's cleaning ability.

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.

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.

Correct Answer: A) To prevent premature ignition and reduce fire risk

Explanation: A high flash point indicates that the oil can withstand higher temperatures before igniting, which is crucial in diesel engines where high temperatures are common. This helps in reducing the risk of fire and ensuring safety.

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: 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.