U.S.C.G. Merchant Marine Exam DDE – Unlimited HP Q620 Motor … · 2019-09-11 · Q620 Motor...

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U.S.C.G. Merchant Marine Exam

DDE – Unlimited HP

Q620 Motor Plants

(Sample Examination)

of 51 Q620 Motor Plants

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Q620 Motor Plants U.S.C.G. Merchant Marine Exam DDE - Unlimited HP Illustrations: 28

Choose the best answer to the following multiple choice questions.

1. You are assigned to a river push boat fitted with main propulsion diesel engines operating on the cycle represented in the polar timing diagram shown in the illustration. What combustion cycle event has a duration of 103o? Illustration MO-0206

• (A) Power o (B) Intake o (C) Compression o (D) Exhaust

If choice A is selected set score to 1.

2. Prior to starting the main propulsion diesel engines fitted on your river push boat, the crankcase oil level must be checked. At what checked level would you be required to add make-up oil?

• (A) When the oil level drops below the ADD mark on the side of the dipstick marked ENGINE STOPPED and OIL COLD.

o (B) When the oil level drops below the FULL mark on the side of the dipstick marked ENGINE STOPPED and OIL COLD.

o (C) When the oil level drops to between the ADD and FULL marks on the side of the dipstick marked ENGINE STOPPED and OIL COLD.

o (D) When the oil level drops to where it is no longer visible on the side of the dipstick marked ENGINE STOPPED and OIL COLD.


3. Before shutting down the main propulsion engines on a tractor tug, ideally what should be accomplished FIRST?

o (A) The engine should be operated at rated load for several minutes, then shut down. o (B) The engine should be shut down immediately with no delay period, regardless of the engine

load. o (C) The engine should be operated at a steady, but substantial load for several minutes, then

shut down. • (D) The engine should be operated with the load removed from the engine for several minutes,

then shut down.

If choice D is selected set score to 1.


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4. You are on a salvage tug using main propulsion engines of the type shown in the illustration. Assuming that the piston is properly positioned, what statement represents the procedure for inspection of the compression rings while in place inside the engine? Illustration MO-0227

• (A) The inspection takes place by removing the appropriate air box hand hole cover and viewing through the resulting opening.

o (B) The inspection takes place by removing the appropriate cylinder head valve cover and viewing through the resulting opening.

o (C) The inspection takes place by removing the appropriate oil pan cover and viewing through the resulting opening.

o (D) It is not possible to inspect the compression rings while in place inside the engine.


5. You are analyzing the data used for trend analysis for one of the main propulsion diesel engines on the ship-docking tug to which you are assigned. The cylinder exhaust temperature of one of the cylinders is significantly lower than the others. When analyzing compression and firing pressure data, however, the numbers are within the normal range for this particular cylinder. What condition would produce these results?

o (A) Leaking fuel injector needle valve for affected cylinder. • (B) Excessive carbon build-up on exhaust pyrometer probe of affected cylinder. o (C) Excessive carbon build-up on air inlet ports or valves of affected cylinder. o (D) Leaking exhaust valve on affected cylinder.

If choice B is selected set score to 1.

6. When checking the crankcase oil level on an off-line diesel generator set engine on your ship-docking tug, what should be the oil level as indicated on the dipstick?

o (A) The level should be well above the FULL mark on the dipstick. • (B) The level should be between the FULL and ADD marks on the dipstick. o (C) The level should be below the ADD mark on the dipstick. o (D) The actual level is unimportant as long as it is visible on the dipstick.



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7. You have just replaced a mechanically operated unit injector on a two-stroke cycle auxiliary diesel engine's #1 cylinder on your river push boat. You are using an injector timing tool to set the injector follower height. To do this you must ensure that the fuel cam follower is riding on the fuel cam base circle. Which of the following statements represents the best assurance that the crankshaft is properly positioned?

• (A) The crankshaft should be barred in the direction of rotation until the #1 cylinder's exhaust valves are fully opened.

o (B) The crankshaft should be barred in the direction of rotation until the #1 cylinder's exhaust valves are fully closed.

o (C) The crankshaft should be barred in the direction of rotation until the #1 cylinder's intake valves are fully closed.

o (D) The crankshaft should be barred in the direction of rotation until the #1 cylinder's intake valves are fully opened.


8. An engine that runs rough or expels large amounts of black smoke may indicate a misfiring cylinder. Assume that the auxiliary diesel engines on your river push boat have a fuel injection system that permits the injectors to be disabled for troubleshooting purposes by loosening the high pressure fuel injection line fitting at the injector nozzle while the engine is running and noting the engine response. If before the injector is disabled the engine is running rough and expelling large amounts of black smoke, and after the injector is disabled, the engine continues to run equally rough, but the engine now produces a clear stack, what is indicated?

o (A) This indicates that the cylinder associated with the disabled injector is firing properly, but at least one other injector is misfiring.

o (B) This indicates that the cylinder associated with the disabled injector is firing properly, and all other injectors are firing properly.

o (C) This indicates that the cylinder associated with the disabled injector is misfiring, and at least one other injector is misfiring.

• (D) This indicates that the cylinder associated with the disabled injector is misfiring, but all other injectors are firing properly.


9. The generator drive engines fitted on your articulated tug-barge unit are started by the type of starter shown in figure "B" of the illustration. What is the purpose of the gear train situated between the air turbine rotor shaft and the pinion shaft? Illustration MO-0201

• (A) It DECREASES the speed of the pinion shaft as compared to the air turbine rotor shaft for the purposes of INCREASING starter motor torque.

o (B) It DECREASES the speed of the pinion shaft as compared to the air turbine rotor shaft for the purposes of DECREASING starter motor torque.

o (C) It INCREASES the speed of the pinion shaft as compared to the air turbine rotor shaft for the purposes of INCREASING starter motor torque.

o (D) It INCREASES the speed of the pinion shaft as compared to the air turbine rotor shaft for the purposes of DECREASING starter motor torque.



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Q620 Motor Plants U.S.C.G. Merchant Marine Exam DDE - Unlimited HP Illustrations: 28 10. The main propulsion diesel engines used to power the ship-docking tug to which you are assigned

are started with vane-type air-starting motors designed to operate at 250 psig. The in-line lubricator should provide 3 drops of oil per cranking minute, as long as the in-line lubricator oil viscosity is as specified. If the start air pressure is within the normal range and the oil viscosity is correct, but the oil injection rate is only 1 drop per minute, what should be done?

o (A) The oil in the in-line lubricator should be replaced with oil of lower viscosity than specified. • (B) The in-line lubricator oil injection metering needle valve should be further opened. o (C) The starting air pressure supplied to the air-starting motors should be increased. o (D) The in-line lubricator oil injection metering needle valve should be further closed.


11. An auxiliary diesel engine on your tug uses a starting system similar to the one shown in the illustration. The hand pump is capable of charging the accumulator to the pressure necessary to start the engine and the engine successfully starts. While running, the engine driven pump is not capable of maintaining the accumulator in a state of being fully charged. Which of the following is most likely to be the cause? Illustration MO-0049

o (A) The hydro-starter (C) pistons are worn. • (B) The engine driven pump (H) drive belt is broken. o (C) The unloading valve (I) is set for too high a pressure. o (D) The full-flow filter (G) is bypassing the element.


12. A diesel generator set on your salvage tug has a simplex lube oil strainer of the type shown in the illustration, situated on the discharge side of the lube oil pump. At a specified engine rpm and lube oil temperature, you notice that the pressure drop becomes unacceptably high. When you rotate the cleaning handle you notice that it is extremely difficult to rotate. What should be done? Illustration MO-0057

• (A) After stopping the engine, the strainer element should be withdrawn and soaked in solvent to break up the heavy deposits on the disk stack (C).

o (B) After stopping the engine, the drain plug (B) should be removed to drain the accumulated sludge from the strainer sump.

o (C) The cleaning handle (A) should be forced to rotate, even if it requires an extender handle to produce greater rotating torque.

o (D) No special consideration need be taken as long as the cleaning handle (A) rotates, even if it rotates with great difficulty.



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13. When interpreting the engine lube oil supply header pressures for the main engines on your river push boat, what statement is true assuming that the lube oil pump is engine-driven?

o (A) As the lube oil temperature increases, the supply header pressure tends to decrease, and as the engine rpm increases, the supply header pressure tends to decrease.

o (B) As the lube oil temperature increases, the supply header pressure tends to increase, and as the engine rpm increases, the supply header pressure tends to increase.

o (C) As the lube oil temperature increases, the supply header pressure tends to increase, and as the engine rpm increases, the supply header pressure tends to decrease.

• (D) As the lube oil temperature increases, the supply header pressure tends to decrease, and as the engine rpm increases, the supply header pressure tends to increase.


14. In terms of the diesel fuels burned in auxiliary and main propulsion diesel engines used on board towing vessels, which of the listed fuel properties would be most critical to consider when transferring and forwarding fuel in extremely low ambient temperature conditions?

• (A) Pour point o (B) Ash content o (C) Heating value o (D) Flash point


15. What maintenance practice represents the best protection against moisture carryover to the fuel injection system of the main engines on board your towing vessel?

o (A) Closing the diesel oil day tank vents, particularly when the relative humidity is high. • (B) Periodically opening, then reclosing, the drain valve on coalescing type diesel oil filters. o (C) Periodically opening, then reclosing, the vent valve on coalescing type diesel oil filters. o (D) Frequently replacing fuel injection pump and injector nozzle inlet fuel filters.


16. Which tugboat diesel fuel oil day tank condition would be most likely to result in water contaminated fuel?

• (A) Maintaining relatively low day tank levels when the relative humidity of the atmosphere is high.

o (B) Maintaining relatively low day tank levels when the relative humidity of the atmosphere is low. o (C) Maintaining relatively high day tank levels when the relative humidity of the atmosphere is

high. o (D) Maintaining relatively high day tank levels when the relative humidity of the atmosphere is

low.



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Q620 Motor Plants U.S.C.G. Merchant Marine Exam DDE - Unlimited HP Illustrations: 28 17. The harbor tug to which you are assigned has diesel generators fitted with injectors with the

operating principle as shown in the illustration. What statement is true concerning the metering principle used in this system? Illustration MO-0146

o (A) The amount of fuel injected is dependent upon the cylinder compression pressure and the cylinder compression temperature.

o (B) The amount of fuel injected is dependent upon the distance of plunger travel. o (C) The amount of fuel injected depends upon the injector pre-load torque setting. • (D) The amount of fuel injected is dependent upon the pressure of the inlet fuel to the injector and

the length of time the orifice is open during metering.


18. The ship-docking tug to which you are assigned has a deck winch drive engine fitted with fuel injectors with the operating principle as shown in the illustration. In figure "A" which plunger travel position corresponds to when fuel injection begins? Illustration MO-0144

o (A) 1 • (B) 2 o (C) 3 o (D) 4


19. The generator drive diesel engines on your river push boat are fitted with a multi-plunger injection pump with high pressure fuel lines leading to each hydraulically operated injector. If the engine is allowed to run out of fuel, it may become necessary to purge the high pressure fuel lines of air. How is this accomplished?

o (A) Slackening each high pressure fuel line fitting at the fuel injector while stroking the manually operated priming pump and allowing air to escape, then retightening when bubbly fuel is observed.

o (B) Slackening each high pressure fuel line fitting at the fuel injector while stroking the manually operated priming pump and allowing air to escape, then retightening when a solid stream of fuel is observed.

• (C) Slackening each high pressure fuel line fitting at the fuel injector while cranking over the engine with the starter or rotating the injection pump by hand and allowing air to escape, then retightening when a solid stream of fuel is observed.

o (D) Slackening each high pressure fuel line fitting at the fuel injector while cranking over the engine with the starter or rotating the injection pump by hand and allowing air to escape, then retightening when air bubbly fuel is observed.

If choice C is selected set score to 1.


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20. You suspect that a diesel generator set on your salvage tug has a defective unit injector because the engine, although warm, is running roughly. The two-stroke engine is fitted with mechanically operated unit injectors. When you push and hold down the No. 3 cylinder injector follower, there is no real change, as the engine continues to run roughly as before. What does this indicate?

• (A) The No. 3 cylinder unit injector is faulty. You have successfully isolated the faulty unit injector. o (B) Either the No. 4, No. 5, or No. 6 cylinder unit injector is faulty. The No. 1 and No. 2 cylinder

unit injectors are functioning properly. o (C) The No. 3 cylinder unit injector is functioning properly. One of the other cylinder unit injectors

must be faulty. o (D) Either the No. 1 or No. 2 cylinder unit injector is faulty. The No. 4, No. 5 and No. 6 cylinder

unit injectors are functioning properly.


21. The salvage tug to which you are assigned has main engines fitted with intake and exhaust systems as shown in the illustration. Assume that the vacuum between the air filter and the turbocharger blower inlet is 12" of water column (negative with respect to atmospheric pressure) when the engine is running at 50% of maximum, continuous rated load. What will happen to the suction vacuum when the load is increased to 100% of maximum continuous rated load? Illustration MO-0076

o (A) No change in the depth of vacuum will occur (reading the same inches of water column negative with respect to atmospheric pressure).

o (B) The depth of vacuum will decrease (reading less inches of water column negative with respect to atmospheric pressure).

• (C) The depth of vacuum will increase (reading more inches of water column negative with respect to atmospheric pressure).

o (D) A loss of vacuum will occur (now reading inches of water column positive with respect to atmospheric pressure).


22. The diesel engines on your towing vessel are all protected with dry-type air filters. The air filters should be inspected and replaced in accordance with manufacturer instructions. What is the generally accepted criteria that would dictate when filter replacement becomes necessary?

o (A) The air filter element should be replaced when the pressure drop across the element decreases below the specified minimum.

• (B) The air filter element should be replaced when the pressure drop across the element increases above the specified maximum.

o (C) The air filter element should be replaced when the pressure rise across the element decreases below the specified minimum.

o (D) The air filter element should be replaced when the pressure rise across the element increases above the specified maximum.



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Q620 Motor Plants U.S.C.G. Merchant Marine Exam DDE - Unlimited HP Illustrations: 28 23. In order to determine the restriction across a dry-type air filter on one of the diesel engines on your

ship-docking tug, the engine should be operating at rated speed and load. What instrument would give the most accurate measurement of air filter element restriction?

o (A) A mercury manometer. o (B) A bourdon tube compound gauge. • (C) A water manometer. o (D) A bourdon tube vacuum gauge.


24. What statement is true concerning the primary purpose of an exhaust muffler/silencer fitted on the exhaust system for any diesel engine so equipped?

o (A) Minimize sound attenuation while maximizing exhaust system back pressure. o (B) Minimize sound attenuation while minimizing exhaust system back pressure. • (C) Maximize sound attenuation while minimizing exhaust system back pressure. o (D) Maximize sound attenuation while maximizing exhaust system back pressure.


25. Wire brushing and scraping can be used to remove hard carbon deposits from exhaust system surfaces. When cleaning exhaust systems associated with the diesel engines on the tug to which you are assigned, what technique can effectively be used in conjunction with mechanical cleaning to loosen and soften up these hard carbon deposits?

o (A) Baking off carbon with heat lamps o (B) Treating with carbon tetrachloride solvent • (C) Treating with carbon penetrating solvent o (D) Sand blasting with diamond dust


26. Exhaust system back pressure is customarily measured at the discharge of a turbocharger. If the exhaust system back pressure is higher than normal for a given engine load on your salvage tug at the point of measurement, which of the following conditions would most likely account for this?

o (A) Restricted exhaust ports or valves. o (B) Restricted turbocharger air intake filter. o (C) Restricted turbocharger turbine inlet screen. • (D) Restricted exhaust silencer/muffler.



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27. You are replacing an automotive type cooling water thermostat on one of the diesel generator sets on your ship docking tug. The markings on the original thermostat indicate that it was set to begin opening at 180oF. Which of the following thermostats marked for Celsius would be a replacement that comes closest to the value at which opening begins as compared to the original thermostat?

o (A) 70oC • (B) 80oC o (C) 90oC o (D) 100oC


28. The fresh water cooling systems serving the main engines on your ship-docking tug are arranged as shown in the illustration. If coolant drain valves are inadvertently opened during engine operation, what combination set of symptoms would most likely result? Illustration MO-0138

• (A) Low level in the jacket water expansion tank. High fresh water outlet temperature from the engine. Low fresh water pump(s) discharge pressure.

o (B) Low level in the jacket water expansion tank. Low fresh water outlet temperature from the engine. Low fresh water pump(s) discharge pressure.

o (C) High level in the jacket water expansion tank. High fresh water outlet temperature from the engine. High fresh water pump(s) discharge pressure.

o (D) Low level in the jacket water expansion tank. High fresh water outlet temperature from the engine. High fresh water pump(s) discharge pressure.


29. Suppose your ship docking tug is equipped with 4-stroke diesel generator set drive engines fitted with the type of charge air blower show in Fig. "B" of the illustration. In terms of the pressure of the charge air entering the intake manifold, what statement is true? Illustration MO-0178

o (A) The pressure decreases as the engine speed increases, which is independent of engine load. • (B) The pressure increases as the turbocharger speed increases, which is a function of the

engine load. o (C) The pressure increases as the engine speed increases, which is independent of engine load. o (D) The pressure decreases as the turbocharger speed increases, which is a function of the

engine load.



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Q620 Motor Plants U.S.C.G. Merchant Marine Exam DDE - Unlimited HP Illustrations: 28 30. The two-stroke cycle main propulsion engines on the harbor tug to which you are assigned are fitted

with turbochargers for scavenging purposes. Assume that you are checking the air box drains in an installation that is valved with external drain piping to a drains tank. When you open the air box drain valves, no drainage occurs when in fact there is an accumulation of oil and moisture on the floor of the air boxes. What should you do?

• (A) Mechanically poke through the drain openings with a rod to clear the drains. o (B) Blow through the drain openings with compressed air to clear the drains. o (C) Increase the air box pressure to blow the air box drain openings clear. o (D) Increase the crankcase pressure to blow the air box drain openings clear.


31. You are inspecting the blower of a Roots-blown, two-stroke cycle main propulsion engine on the ocean-going tug to which you are assigned and discover the presence of aluminum dust on the rotors and on the air duct surfaces. What would most likely be the direct cause of this?

o (A) Restricted blower air intake filter. o (B) Restricted scavenging air intake ports. • (C) Worn blower rotor shaft bearings. o (D) Worn blower rotor shaft seals.


32. The lubricating oil system supporting the main propulsion reduction gear on the salvage tug to which you are assigned is fitted with a sea water cooled 4-pass shell and tube lube oil cooler. The water box sacrificial zinc anodes must be inspected periodically. Which of the following listed actions correctly states maintenance criteria pertaining to scale build-up on the zincs as the result of mineral deposits (not to be confused with corrosion scaling)?

• (A) Any accumulated scale build-up on sacrificial zinc anodes should be scraped off until the zinc anodes are shiny.

o (B) Any sacrificial zinc anodes with accumulated scale build-up should be replaced regardless of the degree of deterioration.

o (C) Any accumulated scale build-up on sacrificial zinc anodes should be left intact to ensure proper protection from galvanic corrosion.

o (D) There is no need to check for scale build-up on the sacrificial zinc anodes as this phenomenon is not physically possible.


33. A diesel engine driven winch on your towing vessel is fitted with a reversing reduction gear equipped with dry-type friction clutches. Which of the operational conditions listed below is most likely to result in clutch slippage and associated clutch disc wear?

o (A) Habitually disengaging the clutch at high engine speed. o (B) Habitually disengaging the clutch at engine idle speed. • (C) Habitually engaging the clutch at high engine speed. o (D) Habitually engaging the clutch at engine idle speed.



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Q620 Motor Plants U.S.C.G. Merchant Marine Exam DDE - Unlimited HP Illustrations: 28 34. The main engines on your harbor tug are equipped with over speed trip devices as shown in the

illustration. By what method is the engine shutdown on an over speed condition? Illustration MO-0171

o (A) A trip shaft cam positions all the unit injectors plungers to the top of their respective strokes, preventing plunger reciprocation, which results in engine shutdown.

o (B) The fuel control linkage controlling the unit injector racks goes to the no fuel position, which results in engine shutdown.

• (C) A trip shaft cam positions all the unit injectors plungers to the bottom of their respective strokes, preventing plunger reciprocation, which results in engine shutdown.

o (D) A solenoid valve in the common fuel supply line to the unit injectors is closed, which results in engine shutdown.


35. The main diesel engines on your coast-wise tug are protected with an array of devices designed to provide an alarm or possible shutdown for various unsafe conditions. During the maintenance procedure for adjusting the alarm and/or trip point setting for such a device, which of the following devices would have a time delay associated with it?

o (A) Engine coolant high temperature alarm device. o (B) Engine over speed trip/alarm device. o (C) Engine crankcase high pressure trip/alarm device. • (D) Engine low lube oil pressure trip/alarm device.


36. A main engine on your articulated tug-barge unit has experienced a low coolant water level alarm even though the water level in the expansion tank is normal. Assuming that the float activated switch is designed to open at low coolant level to activate the alarm, which of the following would account for this?

o (A) The float is binding in the float chamber, not permitting the float to drop. o (B) The float level switch contacts are welded closed, not permitting the contacts to open. • (C) The float switch wire connections are loose at the terminals, not permitting continuity through

the switch. o (D) It is not possible for a low coolant level alarm to occur when the water level is normal.



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37. The auxiliary oil-fired fire-tube steam boiler fitted on your towing vessel is equipped with a water level electrode assembly similar to that shown in the illustration. Under normal circumstances, what would be considered a normal operating water level (NOWL)? Illustration MO-0047

• (A) Anywhere from the bottom (tip) of the electrode labeled "B" to the bottom (tip) of the electrode labeled "C".

o (B) Anywhere from the top of the electrode labeled "B" to the bottom of the electrode labeled "B". o (C) Anywhere from the bottom (tip) of the electrode labeled "B" to the bottom (tip) of the electrode

labeled "E". o (D) Anywhere from the top of the electrode labeled "C" to the bottom of the electrode labeled "C".


38. What would be the most practical and efficient way of removing soot deposits from the fire-sides of the tubes of an auxiliary water-tube natural-circulation boiler as fitted on your sea-going tug?

o (A) Use of a suitable acid. • (B) Use of an air lance. o (C) Use of a power driven wire brush. o (D) Use of a high-pressure water jet.


39. While on deck, you are observing the stack of an oil-fired auxiliary boiler installed on your salvage tug. The gases exiting the stack are a dense white smoke. Eliminating water vapor as a possible cause of the white smoke, what would be the correlating flame color as observed through an observation window peephole?

o (A) Yellowish orange or golden yellow flame. o (B) Reddish flame. • (C) Dull or dazzling white flame. o (D) Yellow flame.



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40. The engine manufacturer for the main engines used on your harbor tug specifies a supplemental coolant additive consisting of molybdate and nitrite be used to supplement the heavy-duty antifreeze for the closed, re-circulating fresh water cooling system. A test-strip comparison chart as shown in the illustration is used for coolant testing purposes. If the molybdate concentration color corresponds to row 2 and the nitrite concentration color corresponds to column B, what statement is true? Illustration MO-0211

o (A) It is not possible to determine the molybdate and nitrite concentration levels from the information given.

o (B) The molybdate and nitrite concentrations levels are too high, and a portion of the coolant must be drained and replaced with fresh water.

o (C) The molybdate and nitrite concentrations levels are within acceptable limits, and no further correction is required.

• (D) The molybdate and nitrite concentrations levels are too low, and additional supplementary coolant additive is required.


41. In a closed, re-circulating fresh water cooling system used for the towing winch drive engine on your coastwise towing vessel, what function would chemical treatment with pure ethylene glycol mixed with fresh water primarily perform?

o (A) Freezing point elevation and boiling point depression. o (B) Freezing point and boiling point depression. • (C) Freezing point depression and boiling point elevation. o (D) Freezing point and boiling point elevation.


42. After a main diesel engine on your river push boat has experienced a safety shutdown due to excessive crankcase pressure, why is it important to wait 2 hours before opening the crankcase to investigate the cause of the trip?

o (A) Opening the crankcase before 2 hours has elapsed may result in the engine spontaneously restarting.

o (B) Opening the crankcase before 2 hours has elapsed may result in excessively rapid cooling. o (C) Opening the crankcase before 2 hours has elapsed may result in crankshaft rotation. • (D) Opening the crankcase before 2 hours has elapsed may result in a crankcase explosion.



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43. A main propulsion diesel engine on your ship docking tug has experienced a safety shutdown due to high lubricating oil temperature. What is the appropriate response?

• (A) Allow 2 hours for the engine to cool down before attempting to inspect the engine and correct the cause of the trip before attempting to restart the engine.

o (B) Allow the engine to cool off for two minutes, then restart and monitor the lubricating oil temperature to verify the cause of the shutdown.

o (C) Immediately perform the engine inspections to determine the cause of the high oil temperature safety shutdown.

o (D) Immediately restart the engine, and monitor the oil temperature to verify the cause of the shutdown.


44. When rolling over a main engine on your river push boat prior to starting with the cylinder test valves open to expel any fluids accumulated within the cylinders, a rather large amount of water is discharged. What is the appropriate response?

o (A) Start the engine, but maintain the jacket water expansion tank level higher than normal. o (B) Start the engine, but run the engine with the cylinder test valves cracked slightly open. • (C) Do not allow the engine to be started until the cause of the water discharge has been

determined and corrected. o (D) Start the engine, but monitor all fluid levels very closely, especially that of the jacket water.


45. Suppose the diesel generator set drive engines are of the type shown in the illustration on your ship docking tug. What description best represents the operating cycle and aspiration method? Illustration MO-0165

o (A) Crankcase scavenged, two-stroke cycle engine. • (B) Roots-blown, two-stroke cycle engine. o (C) Roots-blown, four-stroke cycle engine. o (D) Naturally aspirated, two-stroke cycle engine



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46. Suppose the diesel generator set drive engines are of the type shown in the illustration on your towing vessel. Assuming the engine is naturally aspirated, within an individual cylinder in terms of piston stroke and position, under what circumstances are the intake and exhaust valves both open? Illustration MO-0163

o (A) When the piston is at top dead center (TDC) transitioning from the compression stroke to the power stroke.

• (B) When the piston is at top dead center (TDC) transitioning from the exhaust stroke to the intake stroke.

o (C) When the piston is at bottom dead center (BDC) transitioning from the power stroke to the exhaust stroke.

o (D) When the piston is at bottom dead center (BDC) transitioning from the intake stroke to the compression stroke.


47. The harbor tug to which you are assigned has main engines fitted with open type combustion chambers featuring direct injection. Of the listed figures below found in the illustration, which figure represents the most likely type of injector nozzle type? Illustration MO-0148

• (A) 1 o (B) 2 o (C) 3 o (D) 4


48. Which of the following fuel systems is characterized by a complete absence of high pressure fuel lines?

o (A) In-line multi-plunger type system. o (B) Rotary plunger type system. o (C) Common rail type system. • (D) Unit injector type system.


49. The main propulsion engines onboard your river push boat use a lubricating oil filtration scheme as shown in the illustration. What type of filtration system is illustrated? Illustration MO-0184

• (A) Sump filtration o (B) Bypass filtration o (C) Full-flow filtration o (D) Shunt filtration



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Q620 Motor Plants U.S.C.G. Merchant Marine Exam DDE - Unlimited HP Illustrations: 28 50. The main propulsion engines onboard your harbor tug use a lubricating oil system as shown in the

illustration. What item number represents the scavenging lube oil pump? Illustration MO-0183

o (A) 2 • (B) 4 o (C) 9 o (D) 12


51. The generator drive engines fitted on your harbor tug are started by the type of starter shown in figure "A" of the illustration. What type of starter is shown? Illustration MO-0201

o (A) Sliding vane air motor o (B) Turbine type air motor o (C) Radial piston hydraulic motor • (D) Axial piston hydraulic motor


52. The salvage tug to which you are assigned is fitted with generator set drive engines as shown in the illustration. What statement is true in terms of the combustion chamber design? Illustration MO-0006

o (A) The engine uses an open type combustion chamber with a hemispherical fire-deck. o (B) The engine uses turbulence chambers with a hemispherical fire-deck. • (C) The engine uses an open type combustion chamber with a flat fire-deck. o (D) The engine uses pre-combustion chambers with a flat fire-deck.


53. The ocean-going tug to which you are assigned is fitted with auxiliary engines as partly shown in the illustration. What statement is true concerning the valve guide and valve seat arrangements? Illustration MO-0163

o (A) The valve guides are replaceable inserts, and the valve seats are integral (non-replaceable). o (B) The valve guides and the valve seats are both integral (non-replaceable). o (C) The valve guides are integral (non-replaceable), and the valve seats are replaceable inserts. • (D) The valve guides and the valve seats are both replaceable inserts.



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54. The tractor tug to which you are assigned is fitted with main propulsion diesel engines of the type shown in the illustration. In terms of valve operating gear, cylinder liner type, and connecting rod type, what statement is true? Illustration MO-0227

o (A) This is an overhead cam engine, with wet cylinder liners, and marine-type connecting rods. o (B) This is a pushrod operated overhead valve engine, with wet cylinder liners and hinged-strap,

fork-and-blade connecting rods. • (C) This is an overhead cam engine, with jacketed cylinder liners and hinged-strap, fork-and-

blade connecting rods. o (D) This is a pushrod operated overhead valve engine, with jacketed cylinder liners and

conventional connecting rods.


55. The river push boat to which you are assigned has diesel generators fitted with intake and exhaust systems as shown in the illustration. What does the component labeled "2" represent? Illustration MO-0176

o (A) Charge air cooler • (B) Charge air manifold o (C) Exhaust manifold o (D) Wet muffler


56. The tractor tug to which you are assigned has main engines fitted with intake and exhaust systems as shown in the illustration. What statement best describes the configuration of the multiple turbochargers? Illustration MO-0177

o (A) Four (4) turbochargers are used, two for each cylinder bank, to reduce exhaust back pressure.

• (B) Two (2) turbochargers are used, one for each cylinder bank, to reduce exhaust back pressure.

o (C) Two (2) turbochargers are used and configured in series for a two-staging effect to boost charge air pressure.

o (D) Four (4) turbochargers are used and configured in series for a four-staging effect to boost charge air pressure.



8/22/2019


57. The fresh water cooling systems serving the main engines of your towing vessel are of the type shown in the illustration. What statement accurately describes the characteristics of the fresh water cooling circuit? Illustration MO-0137

o (A) The fresh water circuit is a pressurized system using a stationary/marine type 3-way thermostatic control valve for temperature control.

o (B) The fresh water circuit is a pressurized system using an automotive type 2-way thermostatic control valve for temperature control.

• (C) The fresh water circuit is a vented system using a stationary/marine type 3-way thermostatic control valve for temperature control.

o (D) The fresh water circuit is a vented system using an automotive type 2-way thermostatic control valve for temperature control.


58. The auxiliary engines on the ocean-going tug to which you are assigned are fitted with Roots-blowers as shown in the illustration. What statement is true concerning the timing gears as shown in figure "A"? Illustration MO-0135

o (A) The timing gears are straight cut and insure that the blower rotor lobes are properly spaced apart with a close tolerance.

o (B) The timing gears are straight cut and insure that the blower is properly timed to the engine's crankshaft.

o (C) The timing gears are helically cut and insure that the blower is properly timed to the engine's crankshaft.

• (D) The timing gears are helically cut and insure that the blower rotor lobes are properly spaced apart with a close tolerance.


59. The river pushboat to which you are assigned is fitted with main propulsion reduction gears as shown in the illustration. What statement is true concerning this type of reduction gear? Illustration MO-0142

o (A) This type of reduction gear is used with a fixed pitch propeller and a reversing engine. • (B) This type of reduction gear is used with a fixed pitch propeller and a non-reversing engine. o (C) This type of reduction gear is used with a controllable pitch propeller and a non-reversing

engine. o (D) This type of reduction gear is used with a controllable pitch propeller and a reversing engine.



8/22/2019


60. Suppose each of the main propulsion engines on your harbor assist tug is equipped with a variable speed governor equipped with a solenoid actuated shutdown device. After a high temperature alarm, after continuing to rise, what is the most likely engine high temperature condition that would initiate a safety trip shutdown?

o (A) High charge air temperature o (B) High fuel temperature o (C) High exhaust temperature • (D) High jacket water temperature


61. The thermal fluid heating oil system on your articulated tug-barge unit is configured similarly to that shown in the illustration. What system component performs expansion and dearation functions? Illustration MO-0198

o (A) 1 o (B) 2 o (C) 4 • (D) 5


62. Since towing vessels take on fresh water from shore as a source of make-up water for the closed, re-circulating cooling water systems supporting diesel engines, what property of the make-up water is most important in contributing to cooling system problems?

• (A) The amount of dissolved solids associated with mineral content. o (B) The degree of contamination with microbiological organisms. o (C) The amount of dissolved oxygen (and other various gases). o (D) The degree of contamination of suspended solids, such as sand.



8/22/2019


63. What statement concerning fuel cetane rating and the ignition delay period is true as it applies to towboat main propulsion diesel engines?

o (A) The ignition delay period is the lag in time between when fuel injection actually begins and when combustion actually begins, and the higher the cetane rating of the fuel the longer the ignition delay period.

• (B) The ignition delay period is the lag in time between when fuel injection actually begins and when combustion actually begins, and the higher the cetane rating of the fuel the shorter the ignition delay period.

o (C) The ignition delay period is the lag in time between when fuel injection is initiated and when fuel injection actually begins, and the higher the cetane rating of the fuel the longer the ignition delay period.

o (D) The ignition delay period is the lag in time between when fuel injection is initiated and when fuel injection actually begins, and the higher the cetane rating of the fuel the shorter the ignition delay period.


64. The diesel generator on service on your river push boat is undergoing cyclic, rhythmic variations in speed at steady load. When the governor output shaft is disconnected from the fuel control linkage and the linkage is blocked manually, these variations in engine speed stop. What would be an appropriate corrective action?

• (A) Make an adjustment at the compensating needle valve. o (B) Replace the governor drive gears. o (C) Replace the fuel injector nozzle of the misfiring cylinder. o (D) Tighten the bolts securing the governor base to the engine.


65. When preparing to change the oil of the speed control governor of one of the main propulsion engines on your towboat, you should consult the governor instruction manual to determine the proper viscosity of the oil to use. What is the primary factor that will determine the recommended viscosity?

o (A) The output power of the governor as expressed in inch-pounds. o (B) The speed range (from idle to maximum governed speed) of the engine. o (C) The maximum rated power output of the engine. • (D) The operating oil temperature range of the governor.



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66. The main engines on your ocean-going tug are fitted with speed control governors of the type shown in the illustration. What is the purpose of the compensation system, consisting of the buffer cylinder, buffer piston, buffer springs, and compensation needle valve? Illustration MO-0158

• (A) It prevents engine hunting when responding to load changes. o (B) It senses the actual engine speed of rotation. o (C) It senses the engine speed setting delivered from the bridge. o (D) It limits engine speed to a maximum value to prevent over speeding.


67. The river pushboat to which you are assigned has a pneumatic propulsion control system as shown in the illustration. What statement is true concerning transfer of control? Illustration MO-0168

o (A) The transfer valve at the pneumatic remote control station is used to transfer control of propulsion from the pneumatic remote control station to the mechanical slave remote control station or vice versa.

o (B) The transfer valve at the pilot house pneumatic master control station is used to transfer control of propulsion from the pilot house master control station to the mechanical slave remote control station or vice versa.

o (C) The transfer valve at the pilot house pneumatic master control station is used to transfer control of propulsion from the pilot house master control station to the engine room control station or vice versa.

• (D) The transfer valve at the engine room control station is used to transfer control of propulsion from the engine room control station to the pilot house pneumatic master control station or vice versa.


68. The harbor tug to which you are assigned is fitted with a totally pneumatic propulsion control system as shown in the illustration. All propulsion controls function properly from all locations with the exception of the pneumatic remote control station. Here the propulsion engine will run only at idle and neither propulsion clutch will engage regardless of the throttle lever control position. Which of the following system faults best accounts for these symptoms? Illustration MO-0168

• (A) The pilot house/remote transfer valve at the pilot house pneumatic master control station has a blocked remote port.

o (B) The throttle lever control at the pneumatic remote control station has a blocked speed signal pilot air port.

o (C) The local/remote transfer valve at the engine room control station has a blocked remote port. o (D) The attendance valve at the pilot house pneumatic master control station has a blocked outlet

port.



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69. The main engines on your river towboat are fitted with speed control governors of the type shown inthe illustration. What technology is used to transmit the desired speed setting from the navigationalbridge to the final input signal to the engine governor? Illustration MO-0156

o (A) Electronic (variable DC current).o (B) Mechanical (cable or chain).• (C) Pneumatic (variable control air pressure).o (D) Hydraulic (variable control oil pressure).


70. When any low-pressure distilling plant is operated with less than the designed vacuum, the__________.

o (A) capacity increases• (B) heat level riseso (C) scale formation decreaseso (D) heat level drops



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National Maritime Center

Serving Our Nation’s Mariners

10/17/2018

MO-0006

Adapted for testing purposes only from WILBU R, Pounder's Marine Diesel Engines, Sixth edition

Copyright © 1986 by Butterworth's Publishers

Further reproduction prohibited without permission of 51 Q620 Motor Plants



10/18/2018

Adapted for testing purposes only from Engineman 3, 2000 Edition

NAVEDTRA 14331

Further reproduction prohibited without permission

MO-0047




10/18/2018

Adapted for testing purposes only from CATERPILLAR, Service Manual, D353 Industrial and Marine Engines

Copyright © Caterpillar


MO-0049




10/19/2018

Adapted for testing purposes only from GUNTHER, Lubrication

Copyright © 1971 by Raymond C. Gunther


MO-0057




10/19/2018 Adapted for testing purposes only


MO-0076




10/24/2018

Adapted for testing purposes only from KATES/LUCK, Diesel and High Compression Gas Engines, 3rd edition

Copyright © 1974 by American Technical Society

Further reproduction prohibited without permission.

MO-0135




10/24/2018

Adapted for testing purposes only from Marine Propulsion Unit Operating Manual

Copyright © 1988 by Electro-Motive Division, General Motors Corporation


MO-0137 EMD Engine Fresh Water

Cooling System with Heat Exchanger




10/24/2018

Adapted for testing purposes only from Marine Propulsion Unit Operating Manual

Copyright © 1988 by Electro-Motive Division, General Motors Corporation


MO-0138 EMD Engine Fresh Water

Cooling System with Keel Cooler




10/25/2018

Adapted for testing purposes only from Engineman 3

NAVEDTRA 14331


MO-0142 Reversing Reduction

Gear Operation




10/25/2018

Adapted for testing purposes only from NORMAN Diesel Technology: Fundamentals, Service, Repair

Copyright © 2007 by the Goodheart-Wilcox Company, Inc.


MO-0144 Detroit Diesel 71 Series Engine Unit Injector




10/25/2018




MO-0146 Cummins PT Injection System Injector




10/25/2018




MO-0148




10/25/2018

Adapted for testing purposes only from 645E7B Turbocharged Marine Engine/Systems, 1st Edition

Copyright © 1980 Electro-Motive Division of General Motors


MO-0156 Woodward Type PGA Governor

Schematic Diagram


National Maritime Center Serving Our Nation’s Mariners

10/25/2018

Adapted for testing purposes only from PGA Marine Governor

Copyright © 1975 by Woodward Governor Company


MO-0158




10/25/2018

Adapted for testing purposes only from TOBOLDT, Diesel Fundamentals, Service, Repair

Copyright © 1973 by the Goodheart-Willcox Co., Inc.


MO-0163




10/25/2018

Adapted for testing purposes only from TOBOLDT, Diesel Fundamentals, Service, Repair

Copyright © 1973 by the Goodheart-Willcox Co., Inc.


MO-0165




10/25/2018

Adapted for testing purposes only from Falk Marine Reduction Drives,

Installation, Operation and Maintenance Manual

Copyright © 1976 Faulk


MO-0168 Pneumatic Propulsion Control System




10/25/2018

Adapted for testing purposes only from 645E7B Turbocharged Marine Engine/Systems, 1st Edition

Copyright © 1980 by Electro-Motive Division of General Motors


MO-0171 EMD 645 Overspeed and Manual Trips




10/25/2018

Adapted for testing purposes only from KATES, Diesel and High Compression Gas Engines, 3rd Edition

Copyright © 1974 by American Technical Society


MO-0178




10/25/2018




MO-0184 M/E Lubricating Oil System




10/25/2018

Adapted for testing purposes only from Fulton Installation and Operation Manual

Vertical Coil Design Thermal Fluid Heater Model FT-C and FT-S

Copyright © 2013 by The Fulton Companies


MO-0198 Thermal Fluid Heating Oil System




10/26/2018

Fig. A: Adapted for testing purposes only from STINSON, Diesel Engineering Handbook

Copyright © 1981 by Business Journals, Inc.

Fig. B: Adapted for testing purposes only from KUIKEN, Diesel Engines for Ship Propulsion and Power Plants

Copyright © 2012 by Target Global Energy Training


MO-0201 Starting Motors




1/9/2019

Adapted for testing purposes only from EMD 645E9 Turbocharged Engine Maintenance Manual

Copyright © 1973 Electro-Motive Division, General Motors


MO-0227


U.S.C.G. Merchant Marine Exam DDE – Unlimited HP Q620 Motor … · 2019-09-11 · Q620 Motor...

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Transcript of U.S.C.G. Merchant Marine Exam DDE – Unlimited HP Q620 Motor … · 2019-09-11 · Q620 Motor...