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 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
参考解析
解析：
暂无解析
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
第二组Under normal operation, some lubrication oil mist may be discharged from the air compressor to the air start system. This oil may be from excess compressor cylinder lubrication, from faulty oil scraper rings, or may even be suspended oil vapor contaminating the engine room atmosphere and drawn in at the compressor suction. Oil discharge is kept to a minimum by draining the after cooler, air receiver and starting system. If small quantities of lubrication oil do get passed into the starting air system, they will deposit as thin moist film over internal pipe surfaces but are not readily combustible. If a cylinder non-return valve leak while the engine is in operation, some hot gas, possibly with unburned fuel and cylinder lubrication oil, may be blown through the valve to the adjacent air manifold. With further heating from the leaky valve, this, together with the already deposited oil film, will carbonize and form. incandescent carbon. If starting air is applied to the system while still hot, the high pressure air coming into contact with the burning carbon may cause an explosion. Such an explosion will cause a flame to pass back through the air start pipe system, evaporating the deposited oil film and igniting it in the presence of air. Very high velocities and shockwaves are generated which may rupture pipes and fittings.Alternatively, if excessive oil has entered the air start system, a mixture of air and oil droplets may be discharged through the open cylinder non-return valve during starting. This spray may ignite due to high temperatures in the cylinder, causing a flame through the still open valve to the air manifold.To prevent an explosion, air start valves must be correctly maintained and lubricated to ensure correct timing and free movement with positive closing. Oil in the system must be kept to a minimum, pipe lines must be drained and cleaned internally when necessary and oil discharge from air compressors must be kept to a minimum by good maintenance.The passage is mainly aboutA.crankcase explosionB.scavenge box fireC.starting air pipeD.the danger of explosion in the starting air system
According to this passage, if the cylinder non-return valve were not leakyA.an explosion would not be causedB.there still would be a danger of explosionC.oil would not deposit in the air pipeD.pipe lines would not have to be drained
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Which of the listed problems would be indicated by an accumulation of water in one cylinder, in addition to the crankcase of an idle diesel engine?（）AExcessive cylinder linerBwater in the fuel systemCCracked cylinder linerDLeaking lube oil cooler
单选题Fuel oil discharged to the diesel engine cylinder is atomized at the （）AturbochargerBinjection nozzle tipCcarburetorDfuel oil pump
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In addition to lubricating, cylinder oil assists in forming a gas seal and contains （） which clean the cylinder liner.AadditivesBwaterCgreaseDacid solution
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In some designs the cylinder oil is timed so that the oil injects only on the （）.Apiston crownBpiston grooveCpiston skirtDpiston ring belt
单选题Cylinder wall temperature, fuel oil supplier, and oil passage （）.Aare interdependentBare not interdependentChave nothing to do with each otherDare independent
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Pressurized air enters the cylinder via the inlet ports and pushes the remaining exhaust gas from the cylinder in a process known as “（）”.AchargingBsuper chargingCscavengingDexhausting
单选题Cylinder oil is a high viscosity mineral oil, with a （） machined to the anticipated sulfur content of the fuel.ATANBTBNCSANDSBN
单选题（） is used for cylinder and cylinder head, the salt water is used for cooling the lubricating oil, the fresh water in the coolers and the charging air in the air cooler.AThe fuel oilBThe lube oilCThe sea waterDThe fresh water
单选题Maintaining the proper fuel oil temperature will result in （）Athe elimination of valve wearBimproved atomizationCa decrease in cylinder blow-byDan increase in cylinder blow-by
单选题If it becomes necessary to cutout an individual cylinder of a large, low-speed, main propulsion diesel engine, the fuel to that cylinder should be secured and its （）Afuel pump should be removed and all connections blanked offBcylinder oil feed rate should be increased slightly above that used at normal sea speedCcylinder oil feed rate should be reducedDcylinder oil feed rate should be increased to the maximum flow capable of the metering pump
单选题A condition that can increase the foaming tendency of lube oil is （）Aexcessively high oil temperaturesBwater or moisture contaminationCfuel dilutionDlife its cylinder relief vales
单选题Engine coolant accumulating in the diesel engine lubricating oil can result from a （）Alow oil pressureBhigh coolant pressureCleaking fuel injectorDcracked cylinder head or liner
单选题There is a support ring between the cylinder block and collar of the cylinder liner, thus carrying both the liner and the cylinder coverIt also passes to the cooling bores and to the cover（）Acooling waterBcooling oilCrefrigerantDlubricate oil
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
单选题Misfiring in a diesel engine at light loads can be caused by（）Ahigh lube oil temperatureBlow lube oil temperatureCexcessive cylinder coolingDhigh air injection pressure