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单选题
Cast iron pistons used in large propulsion diesel engines are constructed with （）
A
not taper what so ever
B
the skirt being tapered and smaller than the crown
C
the skirt being tapered and larger than the crown
D
the crown being tapered and smaller than the skirt
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The closing of the exhaust valves used on a modern, large, low-speed, main propulsion diesel engine may be directly provided by_______.A.large conical springsB.compressed air pressureC.hydraulic pressureD.exhaust gas pressure
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单选题One major disadvantage of a low-speed diesel as compared to a steam main-propulsion system is（）.A
the extra weight required for the diesel reduction gearingB
a minimum speed for the engines that limits the minimum speed of the vesselC
the higher fuel consumption per SHPD
the low efficiency of the system when a controllable pitch propeller is used
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单选题An advantage of aluminum pistons, when compared to cast iron pistons is （）.A
greater high temperature strengthB
better heat conductivityC
greater weight per cubic inchD
increased resistance to wear
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单选题The possibility of damage from operating a diesel engine at critical speeds is reduced by the use of（）.A
an isochronous governorB
elastic engine mountsC
a vibration damperD
a cast iron bed plate with good flexible qualities
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单选题Control of the main propulsion diesel engines can be shifted from the engine room to the wheelhouse from the （）.A
wheelhouse control stationB
engine room control stationC
captains officeD
chief engineers office
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单选题In large marine diesel engines cylinder oils usually contain additives formulated to impart the （） to clean the rings and grooves.A
inefficiencyB
oilinessC
detergencyD
purity
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单选题Thermocouple pyrometers are used on large, main propulsion diesel engines to indicate the temperature of the（）A
cooling water leaving each cylinderB
fuel oil entering the injectorC
exhaust gases at various locationsD
lube oil at the bearing supplies
考题
单选题Aluminum pistons have （） coefficient of thermal expansion compared with those of cast iron.A
higherB
lowerC
the sameD
none of the above
考题
单选题Starting a large low-speed propulsion diesel engine on diesel fuel during cold weather conditions, will be made easier by （）A
increasing the quantity of starting airB
increasing the lube oil pressureC
heating the engine fuel supplyD
heating the engine coolant
考题
单选题Mist detectors used on large low-speed main propulsion diesel engines monitor and check for the presence of （）.A
fuel oil vapor at the sludge tank ventB
unburned fuel vapors in the scavenge air receiverC
lube oil vapors in the crank caseD
lube oil vapors in the engine room
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单选题Diesel engines are considered safer than gasoline engines because（）.A
they are more heavily builtB
the fuel used is less volatileC
they can be easily reversedD
they operate at a lower speed
考题
单选题（）, so they are widely used on board ship nowadays.A
Diesel engines have more advantages in comparison with gasoline enginesB
Diesel engines have more advantages in comparison to gasoline enginesC
Gasoline engines have more advantages in comparison with diesel enginesD
Gasoline engines have more advantages in comparison to diesel engines
考题
单选题During maneuvering operations for a direct reversing large, low-speed, main propulsion diesel engine, which of the following actions is used to stop the shaft from turning prior to reversing the engine rotation?（）A
Flywheel inertiaB
Admission of starting airC
The way of the vesselD
securing of fuel to the cylinders
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单选题In a large, slow-speed, main propulsion diesel engine, which of the parts listed is under tension when the engine is running?（）A
Bed plateB
ColumnC
EntablatureD
Tie rod
考题
单选题A large, low-speed, main propulsion diesel engine uses sea water to directly cool the （）.A
cylinder headsB
exhaust valvesC
scavenging airD
injectors
考题
单选题（）diesel engines generally have two systems of lubrication:（）a total loss system feeding and a circulating system lubricating the running gear and cooling the pistons.A
Large crosshead type；crossheadsB
High speed；the cylindersC
Large crosshead type；the cylindersD
Four-stroke；pistons and cylinders
考题
单选题Which of the following statements concerning the lubrication of diesel propulsion engines used in vessels over 300 gross tons is most accurate?（）A
Lubrication systems using engine driven lube oil pumps do not require any additional independent arrangement when such arrangements have been proven reliableB
The use of engine driven pre-lube pumps is permitted on vessels with propulsion systems developing less than 500 shaft horsepowerC
When forced lubrication is used for propulsion engines, one independently driven stand-by pumps is to be provided in addition to the necessary pumps for normal operationD
Lubrication systems where two oil coolers are fitted require a minimum of two temperature control devices which may be actuated by similar sensors
考题
单选题Which of the listed types of starting systems is often used on large, low-speed, direct reversing, main propulsion diesel engines?（）A
ElectricB
HydraulicC
AirD
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考题
单选题Cast iron and gunmetal fittings are used freely in small sizes at moderate pressure; large fittings, those for high pressure and temperature are cast or mild steelIn the above sentence, the word “those” means （）.A
east iron firingsB
mild steel fittingsC
small fittingsD
large fittings
考题
单选题Many cast iron pistons are designed with heat dams, which serve to （）A
keep piston crown temperatures elevated for smoother combustionB
reduce the possibility of overheating the top compression ringC
help retain the heat of compression to prevent ignition delayD
help retain the heat of compression to prevent combustion knock
考题
单选题Pistons of marine medium speed diesel engines may be made of （） in order to keep the weight down for balancing purpose at high speed.A
leadB
forged steelC
alloy steelD
aluminum alloy
考题
单选题Valve cages are used on some large diesel engines to （）A
reduce wear on the valve stemB
permit the use of alloy valve seat materialsC
reduce heat transfer from the valve seatD
facilitate valve removal for servicing
考题
单选题The closing of the exhaust valves used on a modern, large, low-speed, main propulsion diesel engine may be directly provided by （）.A
large conical springsB
compressed air pressureC
hydraulic pressureD
exhaust gas pressure
考题
单选题In some modern large diesel engines, which of the following is used as the support for the main bearings?（）A
BedplateB
BlockC
BaseD
Sump
考题
单选题Most large, low-speed, main propulsion diesel engines use duplex lube oil strainer to （）A
decrease the time required between cleaningsB
removes all large and small foreign objectsC
ensure a positive flow of oil at all timesD
ensure that all lube oil has been treated twice
考题
单选题Cold clearances between the skirt of an aluminum piston and the cylinder liner is about （）A
twice as large as with a cast iron pistonB
the same size as with a cast iron pistonC
half as large as with a cast iron pistonD
the same size as the crown of an aluminum piston
考题
单选题Cylinder lubrication oil for low speed main propulsion diesel engines is admitted to each cylinder during （）.A
the power strokeB
the compression strokeC
low load operation onlyD
periods of standby
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