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单选题
The purpose of the skirt or trunk in four-stroke cycle engines is to act in a similar manner to a （）.
A
crosshead
B
crown
C
piston rod
D
connecting rod
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If all other conditions such as bore, stroke, speed, and mean effective pressures are equal, a two stroke/cycle diesel engine will develop approximatelyA.the same indicated horsepower as a four-stroke/cycle engineB.twice the indicated horsepower as a four-stroke/cycle engineC.one half the indicated horsepower as a four-stroke/cycle engineD.one power stroke for every two crankshaft revolutions
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单选题Compared to four-stroke/cycle engines, two-stroke/cycle diesel engines have the disadvantage of （）A
less even torqueB
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fewer power strokes per revolutionD
greater weight/size requirements
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单选题The camshaft drive is designed to maintain proper camshaft speed relative to crankshaft speedIn maintaining this relationship, the camshaft drive causes the camshaft to rotate at（）A
one half crankshaft speed in a two-stroke cycle diesel engineB
crankshaft speed in a two-stroke cycle diesel engineC
two times crankshaft speed in a two-stroke cycle diesel engineD
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单选题Air motion is induced in a four-stroke/cycle diesel engine cylinder to improve air fuel mixing, and is known as（）A
superchargingB
scavengingC
turbulenceD
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单选题The size of the exhaust valve opening is （）A
most critical in a four-stroke cycle diesel engineB
most critical in a two-stroke/cycle diesel engineC
most critical in a four-stroke/cycle diesel engine if it is turbochargedD
of equal importance in a two-stroke/cycle diesel engine as in a four-stroke/cycle diesel engine
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单选题Marine four-stroke diesel engines are mainly （）.A
of crosshead typeB
of trunk piston typeC
of low speed typeD
all the above
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单选题Proper lubrication of the main bearings is more easily obtained in a single acting, four-stroke/cycle diesel engine than in a tow-stroke/cycle diesel engine because（）.A
The direction of pressure on the journal in four-stroke engine is continuouslyB
positive feed lubricators are installed on all bearings of four-stroke engine, whereas as a splash feed system is used on tow-stroke engineC
four-stroke engines usually utilize a heavier grade of oil than tow-stroke enginesD
Low-stroke engines usually consume less lube oil than four-stroke engines
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单选题Proper lubrication of the main bearing is more easily obtained in a single acting four-stroke/cycle diesel engine than in a single acting two-stroke/cycle diesel engine because （）A
bearing pressure in a four-stroke/cycle acting single diesel engine is continually reversedB
bearing pressure in a two-stroke/cycle single acting diesel engine is continually reversedC
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two-stoke/cycle diesel engines require more complicated lubrication piping
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单选题Oil control rings used in two-stroke/cycle diesel engines are located near the bottom of the piston skirt in order to （）A
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maintain an oil film on the lower liner where scuffing is prevalentC
keep excess oil away from intake and exhaust portsD
help cushion piston skirt side thrust by providing a hydrodynamic oil wedge
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单选题Which of the following statements is true regarding the installation of piston rings on two-stroke/cycle, diesel engines as compared to four-stroke/cycle, diesel engines?（）A
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Some provision must be made in a two-stroke/cycle engine to keep the rings from binding in the portsC
No gap is required to exist between the ends of the ring when cold in a two-stroke/cycle engine, but a small gap is required in a four-stoke/cycle engineD
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单选题If all other conditions such as bore, stroke, speed, and mean effective pressures are equal, a two-stroke/cycle diesel engine will develop approximately（）A
the same indicated horsepower as a four-stroke/cycle engineB
twice the indicated horsepower as a four-stroke/cycle engineC
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单选题During the power stroke of a four-stroke/cycle diesel engine, most of the side thrust of a trunk-type piston is absorbed by the（）A
piston skirtB
pinionC
crossheadD
compression rings
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单选题In today’s practice, with cylinders of equal diameter of bore and equal revolutions, the two-cycle engine delivers a power about 80 percent （） than that of the four-stroke one.A
greaterB
betterC
smallerD
less
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单选题Any increase in the exhaust back pressure of a four-stroke/cycle diesel engine will （）.A
reduce engine horsepower outputB
aid in silencing the exhaust noiseC
increase the mean effective pressureD
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单选题A two-stroke/cycle diesel engine requires less starting air than a four-stroke/cycle diesel engine, of equal displacement, because the two-stroke/cycle diesel engine（）A
has little or no internal frictionB
has a lower effective compression ratioC
operates with scavenge air under a positive pressureD
operates without energy absorbing intake and exhaust strokes
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单选题The speed of the turbocharger for a four-stroke/cycle diesel engine driving a generator at constant speed depends on the （）A
engine speedB
kilowatt loadC
fuel injection pressureD
air intake manifold temperature
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单选题If a four-stroke/cycle diesel engine is running at 1550 RPM, the speed of the camshaft will be（）.A
525 RPMB
775 RPMC
1550 RPMD
1800 RPM
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单选题During which of the listed piston stroke of a four-stroke/cycle diesel engine, is the piston moving downward?（）A
Intake strokeB
Compression strokeC
Exhaust strokeD
Pumping stroke
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单选题Fuel oil begins injection into the cylinder of a four-stroke/cycle diesel engine during the （）.A
intake strokeB
exhaust strokeC
power strokeD
compression stroke
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单选题For a given size engine, the two-stroke/cycle diesel engine will deliver more power than a four-stroke/cycle diesel engine because （）.A
it has a longer power strokeB
more air gets into the cylinder each strokeC
it develops twice as many power strokes at the same speedD
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单选题A turbocharged, four-stroke/cycle diesel engine has a larger valve overlap than a naturally aspirated four-stroke/cycle diesel engine, in order to in crease the （）.A
temperature of the exhaust gasesB
energy supplied to the turbochargerC
air pressure to the intake manifoldD
purge of exhausted gases from the cylinders
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单选题Turbocharged four-stroke/cycle diesel engines utilize valve overlap for（）.A
improving cylinder scavengingB
preheating the combustion chamberC
reducing air charge densityD
preventing valve wear
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单选题The camshaft on a four-stroke/cycle diesel engine provides a means to operate the （）.A
fuel injectorsB
exhaust valvesC
intake valvesD
all of the above
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单选题A piston in a four-stroke/cycle diesel engine makes four strokes during each （）.A
crankshaft revolutionB
mechanical cycle of operationC
period of two combustion cyclesD
cycle of two events
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