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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 engine
B
two power strokes in a two-stroke/cycle engine
C
one power stroke in a two-stroke/cycle engine
D
two piston strokes in a two-stroke/cycle engine
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更多 “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” 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
All diesel engines are classified as ______．A.Four cycleB.Compression ignitionC.Vacuum ignitionD.External combustion
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 the intake valves open （）A
before TDC and close after BDCB
after TDC and close after BDCC
before TDC and close before BDCD
after TDC and close before BDC
考题
单选题Which of the following problems represent one possible cause of high lube oil consumption in a four stroke diesel engine?（）A
Worn intake valve guidesB
Pitted pre-combustion chambersC
Loose valve tappetsD
High exhaust back pressure
考题
单选题In order to keep excess oil from the intake ports in two-stroke/cycle diesel engines, （）A
wide compression rings are usedB
oil rings are located above the pistonC
chromium plating is used on all piston ringsD
oil rings are located near the bottom of the piston skirt
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Marine four-stroke diesel engines are mainly （）.A
of crosshead typeB
of trunk piston typeC
of low speed typeD
all the above
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During the valve overlap period, the exhaust pressure of a turbochargers, four-stroke/cycle diesel engine must be less than the intake manifold pressure to ensure （）A
effective cylinder scavenging and coolingB
constant pressure from the turbochargersC
cooler operation of the exhaust systemD
effective constant pressure for turbocharger operation
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Electrically operated safety devices on auxiliary diesel engines function to stop the engine by （）.A
increasing the volume of intake airB
shutting off the fuel supplyC
increasing the engine back pressureD
over-speeding the engine
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The working cycle of a four-stroke diesel engine consists of four events:（） (1) compression (2) expansion (3) exhaust (4) suctionThe correct sequence isA
(4)-(2)-(3)-(1)B
(4)-(3)-(1)-(2)C
(4)-(3)-(2)-(1)D
(4)-(1)-(2)-(3)
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Which of the following conditions can cause above normal air temperature to develop in the intake manifold of a four-stroke/cycle turbo-charged diesel engine?（）A
Clogged air intake faltersB
Piston blow-byC
A defective after-coolerD
Faulty exhaust valves
考题
单选题Directional intake ports in diesel engines are used to （）.A
reduce air charge turbulenceB
induce air swirlC
deflect hot combustion gas away from the valvesD
oppose the effects of piston induced squish
考题
单选题Which of the following statements is correct regarding a turbocharged four-stroke/cycle diesel generator?（）A
At zero load the intake manifold pressure is greater than the exhaust manifold pressureB
At full load the intake manifold pressure and exhaust manifold pressure are equalC
At full load the intake manifold pressure is less than the exhaust manifold pressureD
At full load the intake manifold pressure is greater than the exhaust manifold pressure
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In comparison to exhaust valves, intake valves of diesel engines may be fabricated from low alloy steels because （）.A
the beveled edges of the intake valves provide for serf-centering during seatingB
intake valves utilize stellite-coated valve seat inserts which reduce wearC
the volume of air passing through intake valves is less than the volume of air passing through exhaust valvesD
intake valves are less affected to the corrosive action of exhaust gases
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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