单选题Cracks in cylinder and cylinder covers may () from unequal heating.AmakeBcauseCresultDproduce

单选题
Cracks in cylinder and cylinder covers may () from unequal heating.
A

make

B

cause

C

result

D

produce


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If fuel injection to a four-stroke/cycle diesel engine begins earlier than designed, ignition may be delayed because theA.cylinder compression pressure may not be high enoughB.cylinder compression temperature may be too highC.fuel oil injection pressure may not be high enoughD.scavenge and purge process is incomplete

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

If the flame from combustion in the cylinder of a four-stroke engine past the piston into the space below, the accumulation of flammable mixture would be ignited, thus resulting in _____.A.the crankcase explosionB.lifting of the cylinder safety valveC.a scavenge fireD.opening of the manhole

The main factor which determines the output of each cylinder is _____.A.the cylinder weightB.the cylinder boreC.the cylinder lengthD.the cylinder cover

One cylinder of a diesel engine is persistently knocking and does not cease(停止) when the fuel supply to that cylinder is secured.Which of the following problems may be the cause?A.Low loading of the cylinderB.Excessive cooling of that pistonC.Sluggish ring action on the pistonD.A mechanical defect in a working part

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Fix the fuel injector into () after repair.Athe cylinder linerBthe cylinder coverCthe cylinder jacketDthe piston

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Diesel engine cylinder head test cocks are used to()Acheck cylinder lubrication prior to starting engineBconnect exhaust gas analyzers to determine engine efficiencyCpressure test cylinder heads to check for leaksDremove moisture accumulations from cylinder prior to starting

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The cooling liquid used for the cylinder may be referred to as ().Ajacket waterBmake-up waterCboiler waterDflushing water

单选题The cylinder covers are secured by eight elastic holding down arranged in four pairs()AnutsBscrewsCstudsDflanges

单选题An increase in crankcase pressure generally indicates()Aworn connecting rod bearingsBworn engine cylinder linersChigh cylinder firing pressureDstuck spring-loaded manhole covers

单选题High firing pressures and a low exhaust temperature in a diesel engine may result from ().Adecreased piston to cylinder head clearanceBincreased exhaust system back pressureCearly fuel injection timingDlow scavenge air temperature

单选题If water is found in the crankcase of a diesel engine, the cause may be due to()Aa cracked cylinder headBa leaky cylinder head gasketCa cracked cylinder linerDany of the above

单选题Persistent knocking of one cylinder of a diesel engine ceases when the fuel supply to that cylinder is securedThis problem may be a result of ()Alow loading of that cylinderBfaulty combustion in that cylinderCsluggish piston ring actionDexcessive piston cooling

单选题If the flame from combustion in the cylinder of a four-stroke engine past the piston into the space below, the accumulation of flammable mixture would be ignited, thus resulting in ().Athe crankcase explosionBlifting of the cylinder safety valveCa scavenge fireDopening of the manhole

单选题For one or two types of engine,the piston and rod can be withdrawn downwards from the cylinder into the crankcase and then out through ().Athe cylinder coverBthe bottom of bed-plateCthe sumpDthe crankcase door

单选题For one or two types of engine, the piston and rod can be withdrawn downwards from the cylinder into the crankcase and then out through the ().Acylinder casingBcylinder boreCcrankcase doorDaperture in the cylinder block

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The cylinder covers and the liners are bolted together by means of ().Abolts welded into the cylinder headBbolts welded into the cylinder framesCstuds screwed into the cylinder headDstuds screwed into the cylinder frames

单选题The cylinder covers and the liners are bolted together by means of studs () the cylinder frames.Ascrewing intoBbeing screw onCto screw onDscrewed into

单选题Cracks in the cylinders and cylinder covers may () unequal heating.Aresult fromBresult inCgive outDgiven from

单选题Cracks in cylinder and cylinder covers may () from unequal heating.AmakeBcauseCresultDproduce

单选题A piston is said to be at top dead center when it is ()Aopening the exhaust portsBplaced on top of the engine along its centerlineCfarthest from the cylinder headDnearest to the cylinder head

单选题If an inflatable liferaft is overturned,it may be righted by().Afilling the stabilizers on one side with waterBreleasing the CO2 cylinderCpushing up from under one endDstanding on the inflating cylinder and pulling on the straps on the underside of the raft