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单选题
The main purpose of the piston oil scraper rings is to （）.
A
seal the space between the piston and the liner
B
reduce the amount of lube oil burned in the combustion chamber
C
transmit heat from the piston to the cylinder liner
D
damp out fluctuations of the piston side thrust
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考题
Which of the following statements represents the function of the compression rings installed at the top of a diesel Engine piston?A.Control the amount of lube oil burned in the combustion chamberB.Transmit heat from the piston to the cylinder linerC.Prevent damage to ring groove inserts by acting as a heat damD.Dissipate combustion chamber gas pressure by channeling it through the ring gap
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Diesel engine blow-by is the leakage of combustion gases past the( ).A.oil rings onlyB.compression and scraper ringsC.cylinder liner sealingD.cylinder liner ring grooves
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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
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If a used lube oil analysis indicates excessive chromate content, this meansA.air filtration is inadequateB.engine coolant is leaking into the lube oilC.fuel oil is leaking into the lube oilD.the piston rings are excessive worn
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单选题Around the combustion chamber, all the main components are to give low thermal strains and the smallest, circumferentially symmetric deformations for good sealing between piston rings and liner（）A
drill cooledB
hole cooledC
tube cooledD
bore cooled
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Worn main bearings in a diesel engine can result in （）A
decreased compression pressureB
increased lube oil pressureC
lower lube oil temperatureD
excessive leakage past the piston rings
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
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单选题The film of oil between the rings and the liner is not only essential for the lubrication but also plays an important part in achieving （）.A
an oil sealB
removing heatC
a gas sealD
cooling the piston
考题
单选题Telescopic pipes to the piston of a large slow-speed main propulsion diesel engine are designed to prevent （）.A
excessive crankcase pressureB
excessive lube oil temperatureC
contamination of the lube oil by waterD
contamination of the cooling water by lube oil
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Black areas on the sealing surfaces of piston rings indicate（）A
lube oil pumpingB
rotating ringsC
gas pressure behind the ringD
passage of hot gases
考题
单选题Improper cooling of a diesel engine cylinder liner due to the accumulation of scale deposits may cause （）.A
low compression pressureB
increased piston wearC
increased cylinder lube oil consumptionD
poor contact between compression rings and liner
考题
单选题Why are some diesel engine cylinder liners plated on the wearing surface with porous chromium?（）A
The chromium will not wear out the piston ringsB
The chromium strengthens the liners in the way of the scavenging air portsC
Chromium eliminates the need for oil scraper ringsD
Pores in the plating aid in maintaining the lube oil film
考题
单选题Improperly fitted piston rings in a diesel engine can cause（）A
excessive lube oil consumptionB
lower than normal lube oil temperatureC
higher than normal exhaust back pressureD
excessive crankshaft end play
考题
单选题Incomplete combustion in a running diesel engine can cause piston rings to become stuck as a result of （）A
residual carbon depositsB
lube oil viscosity breakdownC
uneven heat expansion of the ringsD
uneven heat expansion of the piston
考题
单选题The purpose of an oil mist detector in a main propulsion diesel engine is to warn of （）A
excessive mist density in the crankcasesB
excessively high crankcase vacuumC
excessively high bearing temperatureD
excessive carbon buildup in the lube oil
考题
单选题Which of the following statements represents the function of the compression rings installed at the top of a diesel Engine piston?（）A
Control the amount of lube oil burned in the combustion chamberB
Transmit heat from the piston to the cylinder linerC
Prevent damage to ring groove inserts by acting as a heat damD
Dissipate combustion chamber gas pressure by channeling it through the ring gap
考题
单选题In a medium speed diesel engine, a trunk type piston may be cooled by（） Ⅰ.oil circulation though passages in the piston crown Ⅱ.heat transfer through piston rings and liner wallA
Ⅰ onlyB
Ⅱ onlyC
either Ⅰ or ⅡD
neither Ⅰ or Ⅱ
考题
单选题The main function of piston compression rings is to （）A
prevent excessive cylinder liner wearB
reduce friction losses in the engineC
seal the space between the piston and the linerD
limit upward flow of lube oil into the combustion space
考题
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
考题
单选题The cylinder oil is pumped into the cylinder (via non-return valves) when the piston rings pass the lubricating orifices during （）A
the upward strokeB
the downward strokeC
the power strokeD
the suction stroke
考题
单选题All the rings are slightly rounded on their external top and bottom edges to keep the oil film on the cylinder liner during （） for new piston rings.A
the running-in periodB
the running processC
gas exchange processD
the boiler firing
考题
单选题If a used lube oil analysis indicates an excessive chromate content, this means （）A
air filtration is inadequateB
engine coolant leaking into the lube oilC
fuel oil is leaking into the lube oilD
the piston rings are excessively worn
考题
单选题The function of diesel engine piston compression rings is to （）.A
prevent piston side thrustB
prevent engine friction lossesC
transmit heat from the piston to the cylinder linerD
remove oil from the cylinder combustion space
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Around the combustion chamber, all the main components are bore cooled to give low strains and the smallest, circumferentially symmetric deformations for good sealing between piston rings and liner（）A
thermalB
mechanicalC
plasticD
elastic
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