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单选题
In a four-stroke/cycle diesel engine, the camshaft rotates at （）
A
twice the crankshaft speed
B
half the crankshaft speed
C
the same speed as that of the crankshaft
D
a speed independent of that of the crankshaft
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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What is the speed of the crankshaft in a four-stroke/cycle engine when the camshaft is turning at 750 rpm?（）A
375 RPMB
500 RPMC
750 RPMD
1500 RPM
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In a four-stroke engine the camshaft rotates at （）.A
half the engine speedB
twice the engine speedC
the engine speedD
four times the engine speed
考题
单选题The reversing cams of some four-stroke/cycle diesel engines are brought into position by （）A
sliding the camshaft along its axisB
rotating the cam 180C
rotating the cam followers 180D
moving the idler sprockets in the drive chain
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The speed of the camshaft in a two-stroke/cycle diesel engine, running at 950 RPM, is （）.A
475 RPMB
950 RPMC
1900 RPMD
2400 RPM
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
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 four-stroke engines the camshaft rotates at （）.A
half the engine rotational speedB
twice the engine rotational speedC
the engine rotational speedD
four times the engine rotational speed
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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