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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
increase the liner area covered by the oil film
B
maintain an oil film on the lower liner where scuffing is prevalent
C
keep excess oil away from intake and exhaust ports
D
help cushion piston skirt side thrust by providing a hydrodynamic oil wedge
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更多 “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 increase the liner area covered by the oil filmB 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” 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
The upper piston rings m large, slow-speed, two-stroke/cycle diesel engines are most effectively lubricated by oil ____.A.fed from mechanical lubricatorsB.thrown off from the main bearingsC.supplied from wick fed drip lubricatorsD.flow from a centrifugal or banjo oiler
考题
Lubrication for the main reduction gears used with diesel engines is usually supplied byA.oil from the main engine sumpB.an independent lube oil systemC.the stern bearing head tankD.the stem bearing sump tank
考题
Which lubricating oil additive is used in diesel engines to reduce the tendency(倾向)for sludge and varnish to form on the engine parts?A.Flash point improversB.Pour point improversC.InhibitorsD.Foam suppressors(抑制物)
考题
单选题If the piston groove drain holes for the oil control rings become clogged, which of the following is likely to occur?（）A
The oil control rings will seal improperly and wear rapidlyB
The piston will overheat due to insufficient lubricationC
Excessive oil will remain on the cylinder wallD
Light brown smoke will emanate from the engine exhaust
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The primary purpose of oil control rings on a diesel piston is to（）A
provide a reservoir for cylinder lubricationB
pump oil into the combustion space for cylinder coolingC
prevent excessive lubricating oil consumptionD
allow hydraulic oil film formation on the cylinder
考题
单选题To function properly, oil control rings used on a diesel engine piston must distribute sufficient oil to all parts of the cylinder wall and must also（）.A
prevent any lubricant from reachingB
prevent excessive lubrication from reaching the combustion spaceC
Provide metal-to-metal contact to seal the cylinder against blow-byD
assure a positive means of scraping carbon accumulation from the cylinder
考题
单选题For most diesel propulsion and generator engines, the over-speed trip device will stop the engine by （）A
moving the governor control to stopB
shutting off the lubricating oil supplyC
tripping the governor emergency stop leverD
shutting off the fuel supply
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 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Thermocouple pyrometers are used on large, main propulsion diesel engines to indicate the temperature of the（）A
cooling water leaving each cylinderB
fuel oil entering the injectorC
exhaust gases at various locationsD
lube oil at the bearing supplies
考题
单选题Mist detectors used on large low-speed main propulsion diesel engines monitor and check for the presence of （）.A
fuel oil vapor at the sludge tank ventB
unburned fuel vapors in the scavenge air receiverC
lube oil vapors in the crank caseD
lube oil vapors in the engine room
考题
单选题When inspecting piston rings through the ports of a two-stroke/cycle diesel engine, black areas on the sealing surfaces are the result of （）A
insufficient lubricationB
improper piston coolingC
blow-byD
overload operation
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In the cylinder head of a two-stroke/cycle diesel engine, valves are used for（）A
air intakeB
a fuel outletC
cooling water inletsD
exhausting combustion gas
考题
单选题What color exhaust will be exhibited when a slow speed two-stroke/cycle main propulsion diesel engine, designed to operate on light and heavy fuel oil, is operated on insufficiently preheated heavy fuel oil?（）A
WhiteB
BlackC
BlueD
Clear
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 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Which of the following statements concerning the lubrication of diesel propulsion engines used in vessels over 300 gross tons is most accurate?（）A
Lubrication systems using engine driven lube oil pumps do not require any additional independent arrangement when such arrangements have been proven reliableB
The use of engine driven pre-lube pumps is permitted on vessels with propulsion systems developing less than 500 shaft horsepowerC
When forced lubrication is used for propulsion engines, one independently driven stand-by pumps is to be provided in addition to the necessary pumps for normal operationD
Lubrication systems where two oil coolers are fitted require a minimum of two temperature control devices which may be actuated by similar sensors
考题
单选题（） providing lubricating films, oil used in marine diesel engines have to remove heat from oil cooled piston.A
Except forB
BesideC
ExceptD
In addition to
考题
单选题Piston compression rings used in a diesel engine function to （）A
transfer heat from the cylinder to the pistonB
scrape oil from the sides of the pistonC
seal the combustion space from the crankcasesD
prevent any piston contact with the cylinder liner
考题
单选题Which lubricating oil additive is used in diesel engines to reduce the tendency for sludge and varnish to form on the engine parts?（）A
Flash point improversB
Pour point improversC
InhibitorsD
Foam suppressors
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