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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 gases
B
energy supplied to the turbocharger
C
air pressure to the intake manifold
D
purge of exhausted gases from the cylinders
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更多 “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” 相关考题
考题
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
考题
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
考题
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
one-fourth times crankshaft speed in a four-stroke cycle diesel engine
考题
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
swept volume charging
考题
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
考题
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
考题
单选题The exhaust system for a turbocharged two-stroke/cycle diesel engine functions to（）A
discharge exhaust gases and smokeB
furnish energy to the turbochargerC
reduce engine room noiseD
all of the above
考题
单选题In a closed cooling system for a turbocharged, four-stroke/cycle diesel engine, fluctuating water pressure can be caused by （）A
improper venting of the cooling systemB
carrying the expansion tank water level too highC
a totally clogged impeller in the cooling water pumpD
an incorrectly set cooling system temperature control
考题
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
the maximum bearing pressure is higher in a single acting two-stroke/cycle diesel engineD
two-stoke/cycle diesel engines require more complicated lubrication piping
考题
单选题Clearance volume scavenging in a turbocharged, four-stroke/cycle diesel engine is accomplished （）.A
during the valve overlap periodB
with only the exhaust valve openC
at a pressure below atmosphericD
without cooling the cylinders or pistons
考题
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
In a two-stroke/cycle engine, the rings run hotter, requiring the end gap to be greaterB
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
The gaps should be staggered on either side of a piston in a two-stroke/cycle engine, while staggering is not necessary in a four-stroke/cycle engine
考题
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
one half indicated horsepower as a four-stroke/cycle engineD
one power stroke for every two crankshaft revolutions
考题
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
考题
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
contribute to effective cylinder scavenging
考题
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
考题
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
考题
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
考题
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
考题
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
考题
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
higher combustion pressure is developed
考题
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
考题
单选题Scavenging in a turbocharged, four-stroke/cycle diesel engine is accomplished（）A
during the valve overlap periodB
with only the exhaust valve openC
at a pressure below atmosphericD
without cooling the cylinders or pistons
考题
单选题A four-stroke cycle, turbocharged, 1000 horsepower diesel engine has been operating under loadThe load suddenly increases, causing excessive black exhaust smoke, and a rapid rise in the lube oil temperatureIn response to this condition, you should:（）A
reduce loadB
check your exhaustC
adjust cooling water temperatureD
increase lube oil flow
考题
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
考题
单选题A two-stroke diesel engine exhaust temperature will be lower than a four-stroke diesel engine of the same displacement because the （） (1) scavenging air is cooling the exhaust gases (2) exhaust cycle time is longerA
(1) onlyB
(2) onlyC
both (1) and (2)D
neither (1) nor (2)
考题
单选题In a turbocharged four-stroke/cycle diesel engine, the exhaust valve remains open until after top dead center and the intake valve opens before top dead center to（）.A
produce a scavenging effect in the combustion spaceB
equalize cylinder and exhaust manifold pressuresC
alleviate the difference in valve size between the intake and exhaustD
flush out condensate that collects after each compression stroke
考题
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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