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BD Marine Engineer Class 2 (Second Engineer) study materials
BD Marine Engineer Class 2 (Second Engineer) study resources

BD Marine Engineer Class 2 (Second Engineer) practice questions

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Question 1Marine Engineering Knowledge and Machinery Operation

In a four-stroke diesel engine, which valve is normally opened during the exhaust stroke?

  1. Exhaust valve Correct answer.
  2. Neither valve
  3. Inlet valve
  4. Both inlet and exhaust valves

Explanation

The exhaust stroke follows the power stroke, and its purpose is to clear burnt gases from the cylinder. The exhaust valve lifts during this stroke while the inlet valve stays closed, so the piston can push the products of combustion out through the exhaust passage.

Question 2Marine Engineering Knowledge and Machinery Operation

A marine diesel engine cylinder liner shows heavy vertical scoring on the thrust side. Which condition most directly explains this?

  1. Too high a compression ratio
  2. A blocked fuel injector nozzle
  3. Inadequate lubrication combined with piston slap Correct answer.
  4. Excessive cooling water temperature

Explanation

Vertical scoring arises from metal-to-metal contact between piston rings and liner when the oil film breaks down. On the thrust side the side load is greatest, so poor lubrication plus piston slap produces the characteristic scoring pattern.

Question 3Marine Engineering Knowledge and Machinery Operation

What is the primary function of the air receiver in a starting air system?

  1. To regulate the fuel rack position during starting
  2. To remove water and oil from the starting air
  3. To store compressed air for engine starting and absorb pressure pulsations Correct answer.
  4. To cool the starting air before it enters the cylinders

Explanation

The air receiver is a pressure vessel that holds a reserve of compressed air sufficient for the required number of starting attempts. Its volume also damps the pressure pulsations delivered by the compressor.

Question 4Marine Engineering Knowledge and Machinery Operation

During a routine watch, the main engine fuel oil viscosity at the injector inlet falls below the specified range. What immediate effect is most likely?

  1. Reduced scavenge air pressure
  2. Increased fuel pump plunger seizure risk
  3. Poor atomisation and incomplete combustion Correct answer.
  4. Higher exhaust valve seating temperature

Explanation

Fuel viscosity controls atomisation quality at the injector. If viscosity drops below the specified band, the spray pattern degrades and combustion becomes incomplete, causing smoke and carbon deposits.

Question 5Marine Engineering Knowledge and Machinery Operation

Which parameter is normally used to detect a leaking exhaust valve in a multi-cylinder engine?

  1. Fuel oil supply pressure
  2. Turbocharger lube oil temperature
  3. Jacket cooling water header pressure
  4. Individual cylinder exhaust temperature Correct answer.

Explanation

A leaking exhaust valve allows hot combustion gas to escape past the seat, raising the exhaust temperature of that cylinder above its neighbours. Comparing individual cylinder exhaust temperatures is therefore the standard diagnostic method.

Question 6Marine Engineering Knowledge and Machinery Operation

What is the purpose of the crankcase breather in a trunk-piston diesel engine?

  1. To relieve pressure and remove oil mist from the crankcase Correct answer.
  2. To drain lubricating oil back to the sump
  3. To cool the crankshaft bearings
  4. To supply combustion air to the cylinders

Explanation

Blow-by past the piston rings raises crankcase pressure and creates oil mist. The breather vents this pressure to atmosphere while its element traps oil mist, preventing a dangerous mist explosion and oil loss.

Question 7Marine Engineering Knowledge and Machinery Operation

A centrifugal purifier is being used to clean heavy fuel oil. Which adjustment most directly controls the separation efficiency for a given oil?

  1. The temperature of the sealing water
  2. The speed of the feed pump
  3. The length of the sludge discharge interval only
  4. The position of the gravity disc Correct answer.

Explanation

The gravity disc sets the position of the oil-water interface inside the bowl. Choosing the correct disc for the oil density keeps the interface in the optimum zone, so separation efficiency depends directly on this choice.

Question 8Marine Engineering Knowledge and Machinery Operation

In a shell-and-tube main engine lubricating oil cooler, what does a rising oil outlet temperature with unchanged cooling water flow indicate?

  1. Lower oil viscosity
  2. A decrease in engine load
  3. Fouling or reduced heat transfer on the water side Correct answer.
  4. Increased oil pump capacity

Explanation

If cooling water flow and engine load are steady, a rising oil outlet temperature means less heat is being removed. Fouled tubes or scale on the water side reduce the overall heat transfer coefficient and cause this symptom.

Question 9Marine Engineering Knowledge and Machinery Operation

Which safety device prevents the main engine from starting while the turning gear is still engaged?

  1. Crankcase oil mist detector
  2. Low lube oil pressure trip
  3. Turning gear interlock Correct answer.
  4. Overspeed trip

Explanation

The turning gear interlock is a mechanical or electrical device that blocks the starting air supply while the turning gear remains engaged. Starting with the gear engaged would cause severe damage to the gear and engine.

Question 10Marine Engineering Knowledge and Machinery Operation

What is the main reason for using a two-stage air compressor with an intercooler on board ship?

  1. To eliminate the need for a receiver
  2. To increase the final delivery pressure beyond the design limit
  3. To reduce delivery temperature and improve volumetric efficiency Correct answer.
  4. To allow the use of smaller pistons

Explanation

Compressing air in two stages with intercooling between them lowers the final delivery temperature and reduces the work of compression. Cooler air entering the second stage also improves volumetric efficiency and overall output.

Question 11Marine Engineering Knowledge and Machinery Operation

A freshwater generator on a ship uses the waste heat of the jacket cooling water. What is the working principle?

  1. Chemical precipitation of dissolved salts
  2. Reverse osmosis across a membrane
  3. Vacuum flash evaporation of heated seawater Correct answer.
  4. Freezing of seawater to form pure ice

Explanation

Jacket water heats seawater, which is then admitted to a chamber held under vacuum so it boils at a low temperature. The vapour is condensed into fresh water, leaving the salts behind in the brine.

Question 12Marine Engineering Knowledge and Machinery Operation

During manoeuvring, the main engine is repeatedly started and reversed. Which component is subjected to the greatest thermal and mechanical cycling?

  1. The fuel oil booster pump
  2. The exhaust valve spindle and seat Correct answer.
  3. The camshaft chain tensioner
  4. The scavenge air receiver

Explanation

Frequent starting and reversing produce rapid changes in cylinder temperature and load. The exhaust valve, exposed to hot gases on one side and cooling on the other, suffers the greatest thermal cycling and mechanical impact at its seat.

Question 13Marine Engineering Knowledge and Machinery Operation

What does a high exhaust gas temperature after the turbocharger turbine, combined with low scavenge pressure, most likely indicate?

  1. Turbine fouling or restricted gas flow Correct answer.
  2. Excessive cylinder lubricating oil feed
  3. Low jacket cooling water temperature
  4. A leaking fuel injector

Explanation

Fouling of the turbine blades or a restriction in the gas passage reduces turbine efficiency, so less energy is extracted and scavenge pressure falls while exhaust temperature after the turbine rises. Cleaning the turbine usually restores the readings.

Question 14Marine Engineering Knowledge and Machinery Operation

Why is a relief valve fitted to the scavenge air space of a large two-stroke engine?

  1. To admit extra air during starting
  2. To regulate the turbocharger speed
  3. To drain condensate from the receiver
  4. To protect the air space against excessive pressure from a crankcase explosion or surge Correct answer.

Explanation

The scavenge air space is a large enclosed volume that can be over-pressurised by a turbocharger surge or by a crankcase explosion propagating through the scavenge ports. The relief valve limits the resulting pressure and protects the structure.

Question 15Marine Engineering Knowledge and Machinery Operation

A governor on a marine diesel generator set is described as isochronous. What does this mean?

  1. It allows speed to droop in proportion to load
  2. It maintains constant engine speed regardless of load within its capacity Correct answer.
  3. It varies speed with the fuel rack position only
  4. It limits speed only at overspeed

Explanation

An isochronous governor holds the engine speed constant as load changes by continuously adjusting the fuel rack. This is essential for parallel alternator operation where frequency must remain steady.

Question 16Marine Engineering Knowledge and Machinery Operation

A main engine fuel injection pump delivers fuel at the correct timing but the quantity is low on one unit. Which cause is most consistent with this symptom?

  1. Low jacket cooling water pressure
  2. Worn plunger and barrel allowing leakage past the clearance Correct answer.
  3. A blocked starting air valve
  4. A fouled turbocharger nozzle ring

Explanation

The delivered quantity depends on the plunger and barrel sealing effectively during the injection stroke. Wear increases clearance and lets fuel leak back, reducing the effective quantity even though timing remains correct.

Question 17Marine Engineering Knowledge and Machinery Operation

What is the purpose of the water seal in a stern tube lubricated by oil?

  1. To prevent sea water ingress and lubricating oil loss at the shaft Correct answer.
  2. To support the weight of the propeller shaft
  3. To drive the shaft generator
  4. To cool the stern tube bearings

Explanation

The stern tube seals separate the sea from the lubricating oil space around the shaft. The aft seal keeps sea water out while the forward seal prevents oil escaping into the machinery space or sea.

Question 18Marine Engineering Knowledge and Machinery Operation

During a crankcase inspection, the oil mist detector alarms on a running engine. What is the correct immediate action?

  1. Increase speed to clear the mist through the breather
  2. Reduce speed and investigate, preparing to stop the engine if the alarm persists Correct answer.
  3. Open the crankcase doors to ventilate the space
  4. Ignore the alarm until the next port

Explanation

Oil mist indicates a hot spot that could lead to a crankcase explosion. The engine should be slowed and the alarm investigated, and if mist persists the engine must be stopped and allowed to cool before any inspection.

Question 19Marine Engineering Knowledge and Machinery Operation

Which statement correctly describes the function of a turbocharger waste gate on a marine auxiliary engine?

  1. It admits cooling water to the turbine casing
  2. It bypasses charge air around the engine to reduce power
  3. It bypasses exhaust gas around the turbine to limit boost pressure Correct answer.
  4. It recirculates exhaust gas into the inlet manifold

Explanation

A waste gate opens at a set boost pressure and diverts part of the exhaust gas around the turbine. This limits turbine speed and boost, protecting the engine from over-pressurisation at high load.

Question 20Marine Engineering Knowledge and Machinery Operation

What is the effect of excessive cylinder liner clearance on piston rings in a trunk-piston engine?

  1. Increased ring movement leading to breakage and blow-by Correct answer.
  2. Improved sealing and lower oil consumption
  3. Higher compression pressure and better starting
  4. Reduced piston slap and quieter running

Explanation

Excessive clearance lets the piston and rings move laterally, so the rings flex and hammer in their grooves. This leads to ring breakage, loss of sealing and increased blow-by and oil consumption.

Question 21Marine Engineering Knowledge and Machinery Operation

What is the main purpose of the jacket cooling water system on a marine diesel engine?

  1. To preheat the fuel oil
  2. To remove heat from the cylinder liners and heads Correct answer.
  3. To supply combustion air
  4. To lubricate the cylinder liners

Explanation

The jacket water circulates through passages around the liners and cylinder heads to carry away combustion heat. This keeps metal temperatures within safe limits and maintains the oil film on the liner surface.

Question 22Marine Engineering Knowledge and Machinery Operation

A ship's main engine uses a constant-pressure turbocharging system. What is the characteristic feature of this arrangement?

  1. All cylinders exhaust into a common manifold before the turbine Correct answer.
  2. Each cylinder exhausts directly to a separate turbine nozzle
  3. The turbine is driven by a separate electric motor
  4. The exhaust gas is cooled before entering the turbine

Explanation

In constant-pressure turbocharging all exhaust pulses discharge into a common receiver, smoothing pressure before the turbine. The turbine then operates at a relatively steady pressure rather than on individual pulses.

Question 23Marine Engineering Knowledge and Machinery Operation

What is the function of the air cooler drain in the charge air system?

  1. To remove condensed moisture from the cooled charge air Correct answer.
  2. To release excess boost pressure
  3. To supply sealing air to the turbocharger bearings
  4. To drain lubricating oil from the air cooler

Explanation

Cooling the charge air causes water vapour to condense, and this condensate must be drained away. Removing it prevents water droplets entering the cylinders and avoids corrosion in the air cooler and manifold.

Question 24Marine Engineering Knowledge and Machinery Operation

In a two-stroke crosshead engine, what is the purpose of the stuffing box between the scavenge space and the crankcase?

  1. To prevent scavenge air and combustion products entering the crankcase Correct answer.
  2. To meter cylinder lubricating oil to the liner
  3. To support the weight of the piston assembly
  4. To cool the piston crown

Explanation

The stuffing box seals around the piston rod so that scavenge air, combustion residues and water cannot pass into the crankcase. This keeps the crankcase oil clean and prevents contamination and pressure build-up.

Question 25Marine Engineering Knowledge and Machinery Operation

Which action best reduces the risk of fuel oil waxing in the fuel system during cold operation?

  1. Maintaining the fuel at a temperature above its cloud point Correct answer.
  2. Adding more sealing water to the purifier
  3. Increasing the fuel injection advance
  4. Reducing the fuel booster pump pressure

Explanation

Wax crystals form when distillate fuel cools below its cloud point and can block filters and pipes. Keeping the fuel heated above the cloud point prevents wax formation and keeps the system flowing.

Question 26Marine Engineering Knowledge and Machinery Operation

Which type of valve is most commonly fitted as the main starting air valve on a large marine diesel engine?

  1. A spring-loaded poppet valve
  2. A rotary plug valve
  3. A piston-operated valve Correct answer.
  4. A non-return valve

Explanation

The main starting air valve is usually a piston-operated (or unbalanced) valve held closed by air pressure and opened by pilot air from the distributor. This design provides a large flow area and rapid opening for reliable starting.

Question 27Marine Engineering Knowledge and Machinery Operation

What is the primary function of the fuel oil booster pump in a marine diesel engine fuel system?

  1. To circulate fuel through the purifier
  2. To atomise the fuel at the injector nozzle
  3. To increase the pressure of fuel supplied to the injection pumps Correct answer.
  4. To transfer fuel from the storage tanks to the settling tanks

Explanation

The booster pump raises the fuel pressure to the level required by the fuel injection pumps, typically around 4–8 bar. It ensures a constant supply and maintains the correct pressure for proper injection.

Question 28Marine Engineering Knowledge and Machinery Operation

In a marine diesel engine, what is the purpose of the cylinder liner cooling water?

  1. To lubricate the piston rings
  2. To seal the combustion chamber
  3. To remove heat from the cylinder liner and maintain proper clearance Correct answer.
  4. To preheat the combustion air

Explanation

Cooling water removes heat from the cylinder liner to prevent overheating, maintain material strength, and control thermal expansion so that piston-to-liner clearance remains correct. It also helps maintain an even temperature distribution.

Question 29Marine Engineering Knowledge and Machinery Operation

What is the main function of the air receiver in a marine compressed air system?

  1. To cool the compressed air
  2. To remove oil and water from the air
  3. To store compressed air and dampen pressure fluctuations Correct answer.
  4. To increase the air pressure

Explanation

The air receiver stores compressed air for various services and smooths out pressure pulsations from the compressor. It provides a reserve capacity to meet sudden demands.

Question 30Marine Engineering Knowledge and Machinery Operation

Which type of bearing is typically used for the main crankshaft bearings of a large marine diesel engine?

  1. Ball bearing
  2. Thin-shell precision bearing
  3. Thick-shell white metal bearing Correct answer.
  4. Roller bearing

Explanation

Large marine diesel engines use thick-shell white metal bearings for main crankshaft bearings because they can accommodate slight misalignment and carry high loads. Thin-shell bearings are more common in medium-speed engines.

Question 31Marine Engineering Knowledge and Machinery Operation

What is the purpose of the crankcase explosion relief valve?

  1. To allow fresh air into the crankcase
  2. To prevent excessive pressure build-up in the crankcase due to an explosion Correct answer.
  3. To relieve excess oil pressure
  4. To drain oil from the crankcase

Explanation

Crankcase explosion relief valves are designed to open rapidly and relieve pressure in the event of an explosion inside the crankcase, thus preventing catastrophic damage to the engine structure.

Question 32Marine Engineering Knowledge and Machinery Operation

What does the term 'scavenge' refer to in a two-stroke diesel engine?

  1. The process of cleaning the fuel injectors
  2. The removal of exhaust gases and filling of the cylinder with fresh air Correct answer.
  3. The lubrication of the cylinder liner
  4. The cooling of the piston crown

Explanation

Scavenging is the process of clearing burnt gases from the cylinder and replacing them with fresh air for the next combustion cycle. It is essential for efficient combustion in two-stroke engines.

Question 33Marine Engineering Knowledge and Machinery Operation

Which of the following is a primary function of the lubricating oil in a marine diesel engine?

  1. To cool the combustion air
  2. To act as a fuel additive
  3. To increase the cetane number of the fuel
  4. To reduce friction and wear between moving parts Correct answer.

Explanation

Lubricating oil reduces friction and wear by forming a film between moving surfaces. It also helps to cool components, clean, and protect against corrosion.

Question 34Marine Engineering Knowledge and Machinery Operation

A marine diesel engine is running at constant load, but the exhaust gas temperature gradually increases while the scavenge air pressure remains steady. Which is the most likely cause?

  1. A leaking exhaust valve Correct answer.
  2. A worn fuel injection pump plunger
  3. A fouled turbocharger turbine
  4. A dirty charge air cooler

Explanation

A leaking exhaust valve allows hot combustion gases to escape into the exhaust manifold, raising the exhaust temperature without affecting scavenge pressure. Other causes like turbocharger fouling or cooler fouling would typically affect scavenge pressure.

Question 35Marine Engineering Knowledge and Machinery Operation

During routine inspection, the piston rings of a medium-speed diesel engine are found to have excessive end gap. What is the most likely consequence?

  1. Increased oil consumption due to ring pumping
  2. Lower exhaust gas temperature
  3. Higher mechanical efficiency
  4. Increased blow-by and reduced compression Correct answer.

Explanation

Excessive ring end gap allows combustion gases to blow by the rings, reducing compression pressure and engine efficiency. It can also lead to increased cylinder liner wear and contamination of the lubricating oil.

Question 36Marine Engineering Knowledge and Machinery Operation

In a four-stroke diesel engine, valve overlap is deliberately provided to:

  1. Improve scavenging of exhaust gases and cooling of the exhaust valve Correct answer.
  2. Decrease the volumetric efficiency
  3. Reduce the compression ratio
  4. Increase the cetane number of the fuel

Explanation

Valve overlap allows both intake and exhaust valves to be open briefly around top dead centre, using the incoming air to help expel residual exhaust gases and cool the exhaust valve. This improves volumetric efficiency and reduces exhaust emissions.

Question 37Marine Engineering Knowledge and Machinery Operation

A ship is manoeuvring in port and the main engine is required to start repeatedly. Which component is most susceptible to overheating due to the frequent starting air admissions?

  1. The fuel injection pump
  2. The starting air compressor
  3. The turbocharger
  4. The air start valve Correct answer.

Explanation

The air start valve is subjected to high-temperature air during starting, and repeated operation can cause overheating and wear. Its seals and seat are particularly vulnerable.

Question 38Marine Engineering Knowledge and Machinery Operation

What is the primary purpose of the scavenge air receiver in a two-stroke diesel engine?

  1. To cool the exhaust gas
  2. To store fuel
  3. To provide a stable supply of scavenge air to the cylinders Correct answer.
  4. To separate oil from the scavenge air

Explanation

The scavenge air receiver acts as a reservoir to ensure a steady supply of air to the cylinders during scavenging. It helps dampen pressure fluctuations from the turbocharger.

Question 39Marine Engineering Knowledge and Machinery Operation

A marine diesel engine's fuel injection timing is advanced. What effect does this have on engine performance?

  1. Reduced fuel consumption and lower NOx emissions
  2. Lower peak pressure and smoother running
  3. Delayed combustion and higher exhaust temperature
  4. Increased ignition delay and higher peak pressure Correct answer.

Explanation

Advancing injection timing causes fuel to be injected earlier into a cooler environment, increasing ignition delay and leading to a rapid pressure rise and higher peak cylinder pressure. This can increase mechanical stress and NOx emissions.

Question 40Marine Engineering Knowledge and Machinery Operation

Why is a cooling water treatment chemical added to the jacket cooling water system?

  1. To lubricate the water pump
  2. To prevent corrosion and scale formation Correct answer.
  3. To increase the boiling point
  4. To improve heat transfer

Explanation

Chemical treatment prevents corrosion of metal surfaces and scale deposition, which can impede heat transfer and cause overheating. It also helps maintain the pH and alkalinity within safe limits.

Question 41Marine Engineering Knowledge and Machinery Operation

In a marine diesel engine, what is the function of the cylinder lubricator?

  1. To inject a measured quantity of cylinder oil into the cylinder liner Correct answer.
  2. To provide oil to the governor
  3. To supply lubricating oil to the crankshaft bearings
  4. To lubricate the turbocharger

Explanation

The cylinder lubricator delivers small, controlled amounts of cylinder oil to the cylinder liner to lubricate the piston rings and liner, reducing wear and preventing seizure. It is essential for the proper operation of large two-stroke engines.

Question 42Marine Engineering Knowledge and Machinery Operation

A ship's main engine is fitted with a constant-pressure turbocharging system. Which statement best describes the exhaust gas arrangement?

  1. The exhaust gas is cooled before entering the turbine
  2. All cylinders exhaust into a common manifold before the turbine Correct answer.
  3. Each cylinder exhausts into a separate pipe to the turbine
  4. The exhaust gas is used to drive a reciprocating engine

Explanation

In a constant-pressure system, all cylinders discharge exhaust into a common large manifold, smoothing out pressure pulses before the gas enters the turbine. This provides a more constant pressure to the turbine and improves efficiency at high loads.

Question 43Marine Engineering Knowledge and Machinery Operation

What is the purpose of the air cooler (charge air cooler) in a marine diesel engine?

  1. To reduce the exhaust gas temperature
  2. To heat the fuel oil
  3. To cool the lubricating oil
  4. To increase the density of the charge air Correct answer.

Explanation

The air cooler reduces the temperature of the compressed charge air, increasing its density and thus the mass of air entering the cylinder. This allows more fuel to be burned, increasing power output and efficiency.

Question 44Marine Engineering Knowledge and Machinery Operation

A marine diesel engine has a governor that is described as 'isochronous'. What does this mean?

  1. The engine speed varies with load
  2. The governor is driven by the camshaft
  3. The governor controls the fuel rack position directly
  4. The engine speed remains constant regardless of load Correct answer.

Explanation

An isochronous governor maintains a constant engine speed irrespective of the load, within its capacity. This is essential for generators that must supply a constant frequency.

Question 45Marine Engineering Knowledge and Machinery Operation

During a routine inspection, water is found in the lubricating oil of a marine diesel engine. Which is the most likely source?

  1. Condensation in the crankcase
  2. Worn main bearings
  3. Leaking cylinder liner O-rings Correct answer.
  4. Leaking fuel injector

Explanation

Leaking cylinder liner O-rings or seals can allow cooling water to enter the crankcase and contaminate the lubricating oil. This is a common cause of water in the oil and requires immediate attention.

Question 46Marine Engineering Knowledge and Machinery Operation

What is the function of the fuel oil settling tank in a marine fuel system?

  1. To measure the fuel consumption
  2. To allow water and impurities to settle out by gravity Correct answer.
  3. To store fuel for immediate use
  4. To heat the fuel to reduce viscosity

Explanation

The settling tank allows heavy fuel oil to stand undisturbed so that water and solid impurities can settle to the bottom, from where they are drained. This pre-treatment reduces the load on the purifier and improves fuel quality.

Question 47Marine Engineering Knowledge and Machinery Operation

A main engine is experiencing low compression pressure on one unit. Which of the following is the least likely cause?

  1. Excessive cylinder liner wear
  2. Worn piston rings
  3. A restricted fuel injector nozzle Correct answer.
  4. Leaking exhaust valve

Explanation

A restricted fuel injector nozzle affects fuel delivery and combustion but does not directly cause low compression pressure. Compression pressure is determined by the sealing of the combustion chamber and the compression ratio.

Question 48Marine Engineering Knowledge and Machinery Operation

In a two-stroke diesel engine, the scavenge air ports are uncovered by the piston near the bottom of the stroke. What is the primary effect of this port timing on engine operation?

  1. It allows exhaust gases to leave and fresh air to enter simultaneously Correct answer.
  2. It increases the compression ratio
  3. It delays fuel injection
  4. It reduces the need for a turbocharger

Explanation

The scavenge ports are uncovered as the piston approaches bottom dead centre, allowing fresh air to enter and help expel exhaust gases through the exhaust ports. This overlapping of scavenge and exhaust port opening is characteristic of two-stroke uniflow or loop scavenging.

Question 49Marine Engineering Knowledge and Machinery Operation

A marine diesel engine is fitted with a hydraulic governor. What is the main advantage of a hydraulic governor over a mechanical governor?

  1. It does not require a speed sensing device
  2. It provides greater power to move the fuel rack Correct answer.
  3. It is simpler and requires less maintenance
  4. It is not affected by changes in oil viscosity

Explanation

A hydraulic governor uses oil pressure to amplify the control force, allowing it to move the fuel rack with greater power and precision, especially on large engines. This results in more responsive and accurate speed control.

Question 50Marine Engineering Knowledge and Machinery Operation

In a large marine diesel engine, the exhaust gas bypass (waste gate) is used on the turbocharger to:

  1. Reduce turbocharger lag
  2. Limit maximum boost pressure at high engine speeds Correct answer.
  3. Cool the exhaust gas before the turbine
  4. Increase boost pressure at low engine speeds

Explanation

A waste gate diverts some exhaust gas around the turbine to limit the maximum boost pressure, preventing overloading of the engine and turbocharger at high speeds. It is a common feature on auxiliary engines and some main engines.