MDE Unit 7 overspeed trip testing proceedures Quiz

MDE 7 Q1

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Overspeed Trip of the Centrifugal Type

Question 1: What is the primary purpose of an overspeed trip of the centrifugal type in a diesel engine?

B) To monitor the engine temperature

C) To prevent engine damage by stopping the engine if it exceeds a predetermined speed

A) To regulate the engine fuel supply

D) To measure the engine’s oil pressure

Answer: C) To prevent engine damage by stopping the engine if it exceeds a predetermined speed
Explanation: The primary purpose of an overspeed trip of the centrifugal type is to protect the engine from damage by stopping it if it exceeds a predetermined speed, thereby preventing potential mechanical failure.

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Question 2: How does a centrifugal overspeed trip mechanism operate?

C) It relies on centrifugal force to actuate a trip mechanism that stops the engine when a certain speed is exceeded

B) It employs a spring-loaded valve to control fuel flow

D) It uses an electronic sensor to monitor engine speed and trigger an alarm

A) It uses a hydraulic piston to regulate engine speed

Answer: C) It relies on centrifugal force to actuate a trip mechanism that stops the engine when a certain speed is exceeded
Explanation: A centrifugal overspeed trip mechanism operates using centrifugal force generated by the rotating engine components. When the engine speed exceeds a set threshold, the force actuates the trip mechanism to stop the engine.

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Question 4: What happens to the centrifugal overspeed trip mechanism if the engine speed returns to normal after an overspeed condition?

C) The trip mechanism requires a complete engine shutdown for reset

D) The mechanism continues to trip intermittently

B) The trip mechanism automatically resets once the speed decreases

A) The trip mechanism remains engaged until manually reset

Answer: B) The trip mechanism automatically resets once the speed decreases
Explanation: Once the engine speed decreases and returns to normal after an overspeed condition, the centrifugal overspeed trip mechanism automatically resets, allowing the engine to resume normal operation.

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Question 3: What component of the centrifugal overspeed trip mechanism is responsible for detecting excessive engine speed?

A) The temperature sensor

B) The centrifugal governor

C) The fuel injection pump

D) The crankshaft position sensor

Answer: B) The centrifugal governor
Explanation: The centrifugal governor is the component responsible for detecting excessive engine speed. It uses centrifugal force to activate the trip mechanism when the engine speed exceeds the set limit.

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Question 5: Which of the following is a common maintenance check for the centrifugal overspeed trip mechanism?

C) Replacing the engine oil filter

A) Checking the engine coolant level

D) Calibrating the turbocharger pressure

B) Inspecting the condition of the centrifugal weights and springs

Answer: B) Inspecting the condition of the centrifugal weights and springs
Explanation: Regular maintenance of the centrifugal overspeed trip mechanism includes inspecting the condition of the centrifugal weights and springs, which are critical for the mechanism's proper operation and reliability.

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MDE 7 Q2

1 / 9

High Coolant Temperature Trip

Question 3: How does a high coolant temperature trip function in a diesel engine?

D) Allows the engine to continue operating at higher temperatures

B) Activates a cooling fan to lower temperature

C) Senses coolant temperature and halts engine operation when overheating occurs

A) Provides additional cooling when temperatures rise

Answer: C) Senses coolant temperature and halts engine operation when overheating occurs
Explanation: The high coolant temperature trip senses when the coolant temperature exceeds a preset limit and shuts down the engine to prevent overheating and potential damage.

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Question 3: What does a high coolant temperature trip do in a diesel engine?

B) It shuts down the engine if the coolant temperature exceeds a set threshold

C) It adjusts the engine speed to manage temperature

D) It activates an external cooling fan

A) It increases fuel supply to compensate for temperature changes

Answer: B) It shuts down the engine if the coolant temperature exceeds a set threshold
Explanation: A high coolant temperature trip is designed to shut down the engine if the coolant temperature exceeds a predetermined limit, preventing overheating and potential engine damage.

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Overspeed Trip

Question 1: How does an overspeed trip function in a diesel engine?

B) Uses centrifugal force to activate the cut-out when speed exceeds the limit

D) Deactivates the fuel pump to reduce speed

C) Increases engine speed to manage high RPMs

A) Activates a warning alarm when speed limits are exceeded

Answer: B) Uses centrifugal force to activate the cut-out when speed exceeds the limit
Explanation: The overspeed trip uses centrifugal force generated by the engine’s rotation to activate the cut-out mechanism if the engine speed exceeds the set limit, preventing potential damage.

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Question 2: Which safety cut-out is designed to prevent engine operation in the event of low oil pressure?

B) High-temperature trip

C) Low coolant level sensor

D) High exhaust temperature trip

A) Oil pressure cut-out

Answer: A) Oil pressure cut-out
Explanation: An oil pressure cut-out is designed to prevent engine operation if the oil pressure drops below a safe level, protecting the engine from damage due to inadequate lubrication.

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Question 5: Which safety cut-out is specifically designed to detect and prevent excessive exhaust gas temperatures?

C) Oil temperature sensor

A) Exhaust temperature trip

D) Engine vibration sensor

B) Fuel filter clogging trip

Answer: A) Exhaust temperature trip
Explanation: An exhaust temperature trip is designed to detect excessive exhaust gas temperatures and prevent engine operation if temperatures exceed safe levels, protecting the engine from potential damage.

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Low Fuel Level Cut-Out

Question 4: How does a low fuel level cut-out function in a diesel engine?

A) Automatically refuels the engine when the fuel level is low

C) Allows the engine to continue operating until the fuel level is critically low

D) Activates an alarm to notify the operator of low fuel levels

B) Stops the engine when the fuel level drops below a certain threshold

Answer: B) Stops the engine when the fuel level drops below a certain threshold
Explanation: The low fuel level cut-out stops the engine when the fuel level drops below a critical threshold to prevent running out of fuel and potential damage to the fuel system.

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Safety Cut-Outs/Trips for Diesel Engines

Question 1: What is the primary function of an overspeed trip in a diesel engine?

A) To control the fuel injection rate

C) To monitor the engine oil temperature

D) To adjust the intake air flow

B) To stop the engine if it exceeds a specified speed

Answer: B) To stop the engine if it exceeds a specified speed
Explanation: The primary function of an overspeed trip is to stop the engine if it exceeds a specified speed, preventing potential damage from excessive rotational speeds.

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Oil Pressure Cut-Out

Question 2: How does an oil pressure cut-out function in a diesel engine?

A) Allows the engine to run regardless of oil pressure

B) Activates an external pump to boost oil pressure

C) Monitors oil pressure and stops the engine when pressure is too low

D) Increases engine speed to manage oil pressure

Answer: C) Monitors oil pressure and stops the engine when pressure is too low
Explanation: The oil pressure cut-out monitors the engine's oil pressure and stops the engine if the pressure falls below a critical level to protect the engine from damage due to inadequate lubrication.

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Question 4: What is the purpose of a low fuel level cut-out in a diesel engine?

A) To prevent fuel contamination

D) To adjust the fuel injection timing

C) To stop the engine if the fuel level falls below a certain point

B) To automatically refuel the engine

Answer: C) To stop the engine if the fuel level falls below a certain point
Explanation: A low fuel level cut-out stops the engine when the fuel level falls below a certain point to prevent running the engine on empty and potentially damaging the fuel system.

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MDE 7 Q4

1 / 4

Restoring Normal Operation After Testing

Question 4: What is the final step after manually testing the HT cooling water high-temperature alarm and shutdown on a diesel generator?

B) Replace the cooling water with fresh water

A) Increase the load to ensure the generator is functioning properly

D) Shut down the generator and perform a full inspection

C) Reset the alarm and shutdown systems and return the HT cooling system to normal operation

Answer: C) Reset the alarm and shutdown systems and return the HT cooling system to normal operation
Explanation: The final step involves resetting the alarm and shutdown systems to their normal operating condition and ensuring the HT cooling system is functioning correctly after the tests.

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Verifying Set Points on HT Cooling Water Alarm and Shutdown

Question 3: After manually testing the high-temperature alarm and shutdown set points, what should be done to verify the accuracy of these set points?

C) Replace the temperature sensor with a new one

A) Run the generator at full load for an extended period

D) Reset the alarm and shutdown system to factory settings

B) Record the temperatures at which the alarm and shutdown occurred and compare them with the set points

Answer: B) Record the temperatures at which the alarm and shutdown occurred and compare them with the set points
Explanation: After testing, it's essential to record the actual temperatures at which the high-temperature alarm and shutdown occurred and compare them to the predetermined set points to ensure accuracy.

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Manual Testing of HT Cooling Water High-Temperature Shutdown

Question 2: How is the high-temperature shutdown set point manually tested on a diesel generator?

D) By simulating a high-temperature condition using an external device

A) By disconnecting the shutdown system and running the generator

C) By lowering the HT cooling water temperature to below the set point

B) By gradually heating the HT cooling water until the shutdown occurs

Answer: B) By gradually heating the HT cooling water until the shutdown occurs
Explanation: The set point for the high-temperature shutdown is tested by gradually increasing the HT cooling water temperature until the system automatically shuts down the generator at the preset temperature.

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Manual Testing of HT Cooling Water High-Temperature Alarm

Question 1: What is the first step in manually testing the set point for the high-temperature alarm on a diesel generator’s HT cooling water system?

D) Bypass the high-temperature sensor

B) Isolate the temperature sensor from the control system

C) Gradually heat the HT cooling water while monitoring the temperature

A) Increase the engine load to maximum capacity

Answer: C) Gradually heat the HT cooling water while monitoring the temperature
Explanation: The first step involves gradually heating the HT cooling water while carefully monitoring the temperature to observe when the high-temperature alarm is triggered.

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MDE 7 Q5

1 / 5

Manual Testing of Lubricating Oil Low-Pressure Shutdown

Question 2: During the manual testing of the lubricating oil low-pressure shutdown set point, what should you do if the shutdown does not activate at the expected pressure?

A) Increase the pressure further until the engine stalls

C) Verify the calibration of the pressure calibrator and retest

D) Manually shut down the engine and report the fault

B) Immediately replace the pressure sensor and restart the test

Answer: C) Verify the calibration of the pressure calibrator and retest
Explanation: If the shutdown does not activate as expected, you should verify that the pressure calibrator is properly calibrated and retest to ensure accurate results.

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Verifying Set Points on Lubricating Oil Low-Pressure Alarm and Shutdown

Question 3: How should the set points be verified after manually testing the lubricating oil low-pressure alarm and shutdown?

A) Run the engine without lubricating oil and observe the results

D) Adjust the engine speed to match the set points

C) Increase the lubricating oil pressure to the maximum allowed value

B) Compare the alarm and shutdown activation pressures with the specified set points

Answer: B) Compare the alarm and shutdown activation pressures with the specified set points
Explanation: The verification process involves comparing the pressures at which the alarm and shutdown were activated with the specified set points to ensure they are correctly set.

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Restoring Normal Operation After Testing

Question 4: After manually testing the lubricating oil low-pressure alarm and shutdown using a pressure calibrator, what should be the next step?

B) Reconnect the pressure sensor and reset the alarm and shutdown systems to their normal settings

C) Drain the lubricating oil and replace it with new oil

A) Permanently increase the engine's lubricating oil pressure

D) Increase the engine load to full capacity and monitor the system

Answer: B) Reconnect the pressure sensor and reset the alarm and shutdown systems to their normal settings
Explanation: After testing, it’s important to reconnect the pressure sensor to the control system and reset the alarm and shutdown systems to their normal operating conditions.

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Final System Check After Testing

Question 5: What is the purpose of performing a final system check after testing the lubricating oil low-pressure alarm and shutdown?

A) To increase the lubricating oil viscosity

D) To decrease the engine's operating temperature

B) To ensure the engine continues running without alarms

C) To confirm that the pressure alarm and shutdown system are functioning correctly after being reset

Answer: C) To confirm that the pressure alarm and shutdown system are functioning correctly after being reset
Explanation: The final system check ensures that the pressure alarm and shutdown systems are properly functioning after the testing and resetting process.

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Manual Testing of Lubricating Oil Low-Pressure Alarm

Question 1: What is the first step in manually testing the set point for the low-pressure alarm on a diesel engine’s lubricating oil system using a pressure calibrator?

A) Increase the engine speed to maximum RPM

C) Gradually decrease the applied pressure using the pressure calibrator while monitoring the alarm system

B) Disconnect the lubricating oil pressure sensor from the control system

D) Completely drain the lubricating oil from the engine

Answer: C) Gradually decrease the applied pressure using the pressure calibrator while monitoring the alarm system
Explanation: The first step involves gradually decreasing the applied pressure with the pressure calibrator to simulate low pressure, while observing when the low-pressure alarm is triggered.

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MDE 7 Q6

1 / 10

9. Propeller Shaft Bearing Temperature Sensor

Question: Why is a temperature sensor fitted to the propeller shaft bearing?

D) To adjust the propeller pitch automatically

B) To detect overheating in the bearing that could lead to failure

A) To maintain the engine’s RPM

C) To monitor the bearing's rotational speed

Answer: B) To detect overheating in the bearing that could lead to failure
Explanation: The temperature sensor helps monitor the bearing’s condition and prevent failure due to excessive heat.

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5. Oil Mist Detector

Question: What is the reason for fitting an oil mist detector in a propulsion engine’s crankcase?

B) To detect the presence of oil mist that could indicate a crankcase explosion risk

A) To monitor the oil level

D) To ensure the oil is properly filtered

C) To measure the viscosity of the engine oil

Answer: B) To detect the presence of oil mist that could indicate a crankcase explosion risk
Explanation: An oil mist detector is fitted to detect potentially dangerous oil mist, which could lead to a crankcase explosion.

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1. Low Oil Pressure Alarm

Question: What is the primary reason for fitting a low oil pressure alarm to a propulsion engine?

C) To warn of inadequate lubrication that could lead to engine damage

A) To alert the crew of excessive fuel consumption

B) To ensure the engine does not overheat

D) To maintain proper engine speed

Answer: C) To warn of inadequate lubrication that could lead to engine damage
Explanation: A low oil pressure alarm is crucial for alerting the crew if the lubrication system fails, which could result in significant engine damage.

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4. Shaft Brake

Question: Why might a shaft brake be fitted to a propulsion engine?

B) To prevent the propeller from rotating when the engine is stopped

A) To slow down the engine in an emergency

C) To increase fuel efficiency during low-speed operations

D) To reduce vibration in the engine room

Answer: B) To prevent the propeller from rotating when the engine is stopped
Explanation: A shaft brake is used to prevent the propeller from turning when the engine is stopped, which is important for safety and maintenance.

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6. Vibration Sensor

Question: What is the purpose of a vibration sensor on a propulsion engine?

A) To reduce noise levels in the engine room

D) To regulate the engine temperature

C) To ensure the engine operates at the correct speed

B) To monitor and detect abnormal vibrations that could indicate mechanical failure

Answer: B) To monitor and detect abnormal vibrations that could indicate mechanical failure
Explanation: Vibration sensors are used to detect unusual vibrations that could indicate problems such as misalignment or imbalance.

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7. Emergency Stop Button

Question: Why is an emergency stop button fitted to a propulsion engine control system?

B) To quickly shut down the engine in case of an emergency

C) To enable faster engine startup

D) To maintain engine RPM during high-load conditions

A) To reduce fuel consumption during idle periods

Answer: B) To quickly shut down the engine in case of an emergency
Explanation: The emergency stop button allows for an immediate engine shutdown in case of a critical situation, ensuring safety.

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8. Gearbox Temperature Sensor

Question: What is the role of a gearbox temperature sensor in a propulsion engine arrangement?

B) To detect excessive heat that could damage the gearbox components

D) To ensure smooth gear changes

C) To monitor the gearbox speed

A) To control the gearbox oil level

Answer: B) To detect excessive heat that could damage the gearbox components
Explanation: A gearbox temperature sensor alerts the crew to overheating, which could lead to gearbox failure.

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3. Overload Clutch

Question: What is the purpose of an overload clutch in a gearbox arrangement?

C) To maintain a constant engine speed

D) To ensure smooth gear shifting

B) To protect the gearbox from damage due to excessive torque

A) To increase the engine’s fuel efficiency

Answer: B) To protect the gearbox from damage due to excessive torque
Explanation: An overload clutch is fitted to protect the gearbox from damage by disengaging when excessive torque is detected.

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10. Lube Oil Filter Differential Pressure Gauge

Question: What is the purpose of a differential pressure gauge on the lube oil filter in a propulsion engine?

B) To monitor the pressure difference across the filter and indicate when it needs cleaning or replacement

A) To measure the oil’s viscosity

D) To increase the engine’s power output

C) To regulate the flow rate of the lube oil

Answer: B) To monitor the pressure difference across the filter and indicate when it needs cleaning or replacement
Explanation: The differential pressure gauge indicates when the lube oil filter is becoming clogged and requires maintenance to ensure proper lubrication.

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2. High-Temperature Alarm

Question: Why is a high-temperature alarm fitted to the cooling system of a propulsion engine?

D) To monitor the fuel temperature

B) To alert the crew of excessive engine temperature that could cause overheating and damage

C) To ensure the gearbox remains properly lubricated

A) To prevent the engine from running too cold

Answer: B) To alert the crew of excessive engine temperature that could cause overheating and damage
Explanation: The high-temperature alarm is designed to notify the crew if the engine is overheating, which could lead to severe engine damage.

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