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
The cylinder oil is pumped into the cylinder (via non-return valves) when the piston rings pass the lubricating orifices, during ______.
A.the upward stroke
B.the downward stroke
C.the power stroke
D.the suction stroke
相关考题：
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
In a diesel engine, when refitting piston rings you should ①check the ring gap at the smallest diameter of the cylinder ②remove carbon from the ring grooveA.①B.②C.①②D.neither ① nor ②
单选题Low compression in a diesel engine can be caused by （）Aclogged coolant passagesBa leaking cylinder head gasketClow fuel oil pressureDworn or broken cylinder liner sealing rings
单选题If the piston groove drain holes for the oil control rings become clogged, which of the following is likely to occur?（）AThe oil control rings will seal improperly and wear rapidlyBThe piston will overheat due to insufficient lubricationCExcessive oil will remain on the cylinder wallDLight brown smoke will emanate from the engine exhaust
单选题The piston rings are manufactured with a diameter （） the bore of the cylinder.Alarger thanBsmaller thanCequal toDnone of the above
单选题The primary purpose of oil control rings on a diesel piston is to（）Aprovide a reservoir for cylinder lubricationBpump oil into the combustion space for cylinder coolingCprevent excessive lubricating oil consumptionDallow hydraulic oil film formation on the cylinder
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（）.Aprevent any lubricant from reachingBprevent excessive lubrication from reaching the combustion spaceCProvide metal-to-metal contact to seal the cylinder against blow-byDassure a positive means of scraping carbon accumulation from the cylinder
单选题Insufficient end clearance on newly fitted piston rings in a diesel enginewill cause the rings to（）Ajam in the most worn part of the cylinder when the rings expandBbreak in the most worn part of the cylinder when the rings expandCwear eccentrically on the side opposite the end gapDoverheat and jam at the top center on the combustion stroke
单选题In some diesel engine designs,（）the injection of cylinder oil is timed to impinge when the piston and only impinge on（）Ais coming upward；cylinder ring beltBis going downward；piston ring beltCis coming upward；piston ring beltDis going downward；cylinder ring belt
单选题Scuffed cylinder liner wearing surfaces in a diesel engines can result from （）Astarting the engine while hotBknurling the piston skirtCoperating the engine overheatedDscuff resistant piston rings
单选题In a diesel engine, when refitting piston rings you should （） Ⅰ.check the ring gap at the smallest diameter of the cylinder Ⅱ. Remove carbon from the ring grooveAⅠ onlyBⅡ onlyCboth Ⅰ and ⅡDneither Ⅰ nor Ⅱ
单选题Improper cooling of a diesel engine cylinder liner due to the accumulation of scale deposits may cause （）.Alow compression pressureBincreased piston wearCincreased cylinder lube oil consumptionDpoor contact between compression rings and liner
单选题When good and steady service conditions have been achieved, the running surfaces of the piston rings and cylinder liner will be（）In addition, the rings will move freely in the grooves and also be well oiled intact, and not unduly worn.Ahazy lightBhazy light brownChazy light blueDhazy light grey
单选题A piston is at bottom dead center when it is（）Aopening the exhaust portsBclosing the fuel portsCfarthest from the cylinder headDnearest to the cylinder head
单选题Which of the following statements represents the function of the compression rings installed at the top of a diesel Engine piston?（）AControl the amount of lube oil burned in the combustion chamberBTransmit heat from the piston to the cylinder linerCPrevent damage to ring groove inserts by acting as a heat damDDissipate combustion chamber gas pressure by channeling it through the ring gap
单选题The main function of piston compression rings is to （）Aprevent excessive cylinder liner wearBreduce friction losses in the engineCseal the space between the piston and the linerDlimit upward flow of lube oil into the combustion space
单选题Oil is supplied to the cylinder wall and （） by means of mechanical lubricators.Athe cylinder coverBthe piston ringsCthe piston crownDthe piston skirt
单选题Scuffed cylinder liner surfaces in a diesel engine can result form（）Astarting the engine hotBknurling the piston skirtCoperating an overheated engineDusing scuff resistant piston rings
单选题The cylinder oil is pumped into the cylinder (via non-return valves) when the piston rings pass the lubricating orifices during （）Athe upward strokeBthe downward strokeCthe power strokeDthe suction stroke
单选题The function of the piston compression rings used in a diesel engine is to （）Aseal the space between the piston and linerBtransmit heat from the piston to the cylinder linerCreduce the amount of combustion gas blow-byDall of the above
单选题The main purpose of the piston oil scraper rings is to （）.Aseal the space between the piston and the linerBreduce the amount of lube oil burned in the combustion chamberCtransmit heat from the piston to the cylinder linerDdamp out fluctuations of the piston side thrust
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.Athe running-in periodBthe running processCgas exchange processDthe boiler firing
单选题If the piston ring gap remains insufficient when installing new rings, youshould（）Ainstall oversized ringsBhone the cylinder liner to allow ring installationCcompress the rings tighter with a compressing toolDfile the ends of the rings
单选题In a refrigeration system, which of the following statements describes the actions occurring when a solenoid valves, used in conjunction with an unloader head is energized?（）AThe solenoid valves directs high pressure gas to the valve lifting device raising the suction valve off its seat and causing one specific cylinder to become unloadedBThe solenoid valves directs high pressure gas to the underside of the unloading piston, causing it to rise and allowing the recirculating ports to be openedCWhen the solenoid valve becomes energized, the valve ports become closed, allowing discharge pressure to build up above the piston, shifting it and causing it to unloadDThe solenoid valve allows the refrigerant to pass from the suction chamber to the top of the unloader piston, causing the piston to lift and unload the cylinder
单选题The function of diesel engine piston compression rings is to （）.Aprevent piston side thrustBprevent engine friction lossesCtransmit heat from the piston to the cylinder linerDremove oil from the cylinder combustion space
单选题Piston compression rings used in a diesel engine function to （）Atransfer heat from the cylinder to the pistonBscrape oil from the sides of the pistonCseal the combustion space from the crankcasesDprevent any piston contact with the cylinder liner
单选题In order to keep the oil film on the cylinder liner during the running-in period, the piston rings are slightly rounded（）Aon both the external and internal top edgesBon both the external top and bottom edgesCon both the external and internal bottom edgesDon all the four edges
单选题If clearance between a piston and the cylinder wall is excessive, piston slap will occurThe slap itself is caused by （）Aalternation of side thrustBa breakdown of the lube oil film on the cylinder wallCworn piston boss piston pin bearingsDfluctuating gas pressure in the combustion space