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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 skirt
B
pinion
C
crosshead
D
compression rings
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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In a single acting, four-stroke/cycle diesel engine, the power impulse in an individual cylinder occurs ()A
once every crankshaft revolutionB
once every two crankshaft revolutionsC
once every piston strokeD
twice every piston stroke
考题
单选题Compared to four-stroke/cycle engines, two-stroke/cycle diesel engines have the disadvantage of ()A
less even torqueB
higher cylinder head temperaturesC
fewer power strokes per revolutionD
greater weight/size requirements
考题
单选题In a four-stroke/cycle diesel engine, after the completion of the power stroke, the piston will move()A
up and draw in a fresh air chargeB
down to burn off fuelC
down to compress the fuel air chargeD
up and force out the exhaust gases
考题
单选题A connecting rod in a four-stroke/cycle diesel engine is subject to()A
tension load twice each crankshaft revolutionB
compression load during power and compression strokesC
inertia load once every four crankshaft revolutionsD
bending loads at bottom and top dead center
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When an air started, four-stroke/cycle diesel engine is being cranked, the starting air is admitted to each cylinder during what would normally be the()A
intake strokeB
compression strokeC
power strokeD
exhaust stroke
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Scavenging in a four-stroke/cycle diesel engine occurs during the ().A
last part of the exhaust stroke, and the first part of the intake strokeB
last part of the intake stroke onlyC
early part of the injection stroke onlyD
early part of the power stroke
考题
单选题In diesel engines, the four basic events (intake, compression, power and exhaust) are performed once in ().A
two crankshaft revolutions in a two-stroke/cycle engineB
two power strokes in a two-stroke/cycle engineC
one power stroke in a two-stroke/cycle engineD
two piston strokes in a two-stroke/cycle engine
考题
单选题A disadvantage of a four-stroke/cycle diesel engine is ()A
higher working temperature of piston and cylinderB
the use of scavenge portsC
fewer power strokes per revolution of the crankshaftD
part of the fuel is burned as the piston is moving away from top dead center
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The two strokes of a two-stroke/cycle diesel engine are ()A
power and intakeB
intake and exhaustC
exhaust and compressionD
compression and power
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If a four-stroke/cycle diesel engine is started by injecting air into the cylinder, the pistons receiving the charge of starting air must be()A
on the power strokeB
on the exhaust strokeC
at the end of the power strokeD
at the start of the intake stroke
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 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
考题
单选题In a four-stroke/cycle diesel engine, the camshaft rotates at ()A
twice the crankshaft speedB
half the crankshaft speedC
the same speed as that of the crankshaftD
a speed independent of that of the crankshaft
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