单选题The crankcases of many diesel engines are kept under a slight vacuum to （）Aimprove fuel economyBincrease the air charge velocityCreduce the risk of explosionDall of the above
单选题
The crankcases of many diesel engines are kept under a slight vacuum to （）
A
improve fuel economy
B
increase the air charge velocity
C
reduce the risk of explosion
D
all of the above
参考解析
解析：
暂无解析
相关考题：
An efficient seal between the cylinder block and cylinder heads on many diesel engines is obtained with________.A.graphite packingB.sealing compoundC.lubricating oilD.gaskets
All diesel engines are classified as ______．A.Four cycleB.Compression ignitionC.Vacuum ignitionD.External combustion
单选题Generally，you can best keep a vessel under steering control when the vessel has（）.AHeadwayBSternwayCNo way on，with engines stoppedDNo way on，with engines full ahead
单选题Compared to four-stroke/cycle engines, two-stroke/cycle diesel engines have the disadvantage of （）Aless even torqueBhigher cylinder head temperaturesCfewer power strokes per revolutionDgreater weight/size requirements
单选题In modern installations, the main engine and the standby auxiliary engines（）Acan be started at low temperature and are free from preheatingBusually are preheated by steam before being startedCare kept at a constant temperature and free from preheatingDare kept at a low temperature to save energy
单选题Scuffed cylinder liner wearing surfaces in a diesel engines can result from （）Achromium plating piston ringsBknurling the piston skirtCextended maximum power operationDapplying load to a cold diesel engine
单选题Diesel engines are considered safer than gasoline engines because（）.Athey are more heavily builtBthe fuel used is less volatileCthey can be easily reversedDthey operate at a lower speed
单选题（）, so they are widely used on board ship nowadays.ADiesel engines have more advantages in comparison with gasoline enginesBDiesel engines have more advantages in comparison to gasoline enginesCGasoline engines have more advantages in comparison with diesel enginesDGasoline engines have more advantages in comparison to diesel engines
单选题The cetane number rates fuels for diesel engines according to its （）Aantiknock characteristicsBignition qualitiesCrates of vaporizationDviscosity
单选题The crankcase of many diesel engines are kept under a slight vacuum by the （）.Ascavenging action of the pistonBpiston type vacuum pump taking suction off a differential manometerCgland exhausting manometerDcrankcase exhaust fan
单选题The crankcases of many diesel engines are kept under a slight vacuum to （）Aimprove fuel economyBincrease the air charge velocityCreduce the risk of explosionDall of the above
单选题Exhaust pipes for separate diesel engines can be combined only when （）Aspace limitations prevent separately run pipesBthe engines are small auxiliary unitsCthey are arranged to prevent gas backflow to each engineDa waste heat boiler is installed
单选题The separation of impurities and water from （） is essential for good combustion of diesel engines.Alube oilBfuel oilCturbine oilDgrease
单选题Some diesel engines are supercharged with a （）Aslam chargerBturbochargerCfuel atomizerDfuel injector
单选题（） the engines, the diesel engine is（） used engine on board.ABetween；more commonlyBAmong；the most commonlyCBetween；not more commonlyDAmong；not the most commonly
单选题An efficient seal between the cylinder block and cylinder heads on many diesel engines is obtained with（）Agraphite packingBsealing compoundClubricating oilDgaskets
单选题A vessel’s Certificate of Documentation（）.Amay be retained by the owner at the home port OR kept on the vesselBmust be posted under transparent material in the pilothouseCmust be carried on boardDmust be kept on file at the corporate offices of the owner or operator
单选题Diesel engines are started by supplying （） into the cylinders in the appropriate sequence for the required direction.Acooling waterBcompressing airCcompressed airDcylinder oil
单选题All diesel engines are classified as（）.Afour cycleBcompression ignitionCvacuum ignitionDexternal combustion
单选题The main operating characteristic of diesel engines which distinguishes them from other internal combustion engines is the （）Amethod of supplying airBcooling systemCmethod of igniting fuelDvalve operating mechanism
单选题An auxiliary reservoir for starting auxiliary engines should be kept at （）.Alow pressure at all timesBfull pressure at all timesClow pressure at intermittenceDfull pressure at intermittence
单选题The responsibilities of the engineer officer in charge of the watch do not include （）Ato ensure the main propulsion plant are kept under constant surveillanceBto ensure the auxiliary systems are kept under constant surveillanceCto inspect the steering gear spaces at suitable intervalsDto inspect and overhaul the equipments in his charge