单选题Critical speed in diesel engines occurs when engine torque pulsations become （）Aopposed to the crankshaft rocking coupleBresonant with the crankshaft natural frequencyCcritical fore and aft crankshaft vibrationsDhorizontal whipping motions of the crankshaft
单选题
Critical speed in diesel engines occurs when engine torque pulsations become （）
A
opposed to the crankshaft rocking couple
B
resonant with the crankshaft natural frequency
C
critical fore and aft crankshaft vibrations
D
horizontal whipping motions of the crankshaft
参考解析
解析：
暂无解析
相关考题：
When transmitted by a reduction gear, diesel engine speed is reduced and the torque available for workA.remains the sameB.is reducedC.is increasedD.is eliminated
In reducing engine speed to an efficient propeller speed by the use of reduction gears, _______.A.speed and torque are both reducedB.speed is reduced and torque remains unchangedC.speed is reduced and torque is increasedD.speed is sometimes unchanged while torque is increased
单选题One major disadvantage of a low-speed diesel as compared to a steam main-propulsion system is（）.Athe extra weight required for the diesel reduction gearingBa minimum speed for the engines that limits the minimum speed of the vesselCthe higher fuel consumption per SHPDthe low efficiency of the system when a controllable pitch propeller is used
单选题（）are increasingly used as main engine on merchant vessels, because they have a high Hp/Weight ratio.ASlow speed diesel enginesBMedium-speed diesel enginesCSteam enginesDGasoline engines
单选题When transmitted by a reduction gear, diesel engine speed is reduced and the torque available for work （）Aremains the sameBis reducedCis increasedDis eliminated
单选题In large, low-speed, main propulsion diesel engine, position ring groove wear usually occurs at the（）Atop of the ring grooveBback of the ring grooveCbottom of the ring grooveDpiston ring end clearance
单选题If keep the fuel injection of main engine unchanged when ship is fouled, that will causeⅠ.The speed of main engine to be reduced Ⅱ.Ship speed to be reduced Ⅲ.The resistance torque of propeller to be increased Ⅳ.Trim at stern to increase（）AⅠ + ⅡBⅠ ~ ⅢCⅠ ~ ⅣDⅠ + Ⅱ + Ⅳ
单选题An over-speed trip stops a diesel engine when the engine （）Aruns out of fuelBhas low lubricating oil pressureCexceeds a set maximum speedDhas high cooling water temperature
单选题For most diesel propulsion and generator engines, the over-speed trip device will stop the engine by （）Amoving the governor control to stopBshutting off the lubricating oil supplyCtripping the governor emergency stop leverDshutting off the fuel supply
单选题A diesel engine which is rated for normal operation at a crankshaft speed of 800 RPM, is commonly classed as a （）.Aslow-speed dieselBmedium-speed dieselChigh-speed dieselDconstant-speed diesel
单选题The knock occurring when a cold diesel engine is started and continues while running at low speed, but stops when the engine reaches normal operating speed and temperature, is（）.Acaused by retarded injection timingBcaused by a mechanical defect in one cylinderCcaused by high fuel injection pressuresDnormal for these conditions
单选题Which of the following procedures should be carried out when a large, low-speed, diesel engine is operated with one cylinder secured?（）ALubrication to the defective cylinder should be increasedBCooling water temperature to the engine should be increasedCOnly the turbocharger speed should be reducedDEngine speed should be reduced
单选题The main function of tie rods in the construction of large, low speed diesel engines is to（）.Astiffen the bedplate in way of the main bearings to increase the engines longitudinal strengthBaccept most of the tensile loading that results from the firing forces developed during operationCmount the engine frame securely to the hull to prevent shaft coupling misalignmentDconnect the crosshead solidly to the piston rod
单选题The size of the exhaust valve opening is （）Amost critical in a four-stroke cycle diesel engineBmost critical in a two-stroke/cycle diesel engineCmost critical in a four-stroke/cycle diesel engine if it is turbochargedDof equal importance in a two-stroke/cycle diesel engine as in a four-stroke/cycle diesel engine
单选题Diesel engine electric starting motors generally require heavier duty motors and motors and operate at higher voltages than comparable starting motors for gasoline engines due to（）Ahigher speed requiredBflywheel-effectClower starting temperaturesDhigher compression pressures
单选题When the vessel on the full speed ahead, if full astern immediately （） the main engine start astern and fuel injection.Aafter the thrust power is zeroBafter the torsion is zeroCsurpass the critical point on the water turbo phaseDafter the speed is zero
单选题The device used to limit engine torque at various engine speeds is called a （）Aspeed limiting governorBvariable speed governorCconstant speed governorDload limiting governor
单选题When attempting to start a main propulsion diesel engine, the engine, the engine turns at the proper speed but will not startYou should check the（）Astarting air pressureBscavenge air pressureCover-speed tripDbanjo oiler line
单选题When the general alarm is sounded continuously, the engine room personnel should （）.Aproceed to their man overboard stationsBstart the fire pumpCput on lifejackets and go to their abandon ship stationsDsecure the propulsion diesel engines and evacuate the engine room
单选题In conventional systems, the injection pressure（）, while it’s（）in common rail diesel engines.Afluctuates with the engine speed to some extent, independent of the engine speedBkeeps constant at all engine speed, dependent on the engine speed to some extentCkeeps constant at all engine speed, independent of the engine speedDis decided by the engine speed, constant at all engine speed
单选题In a large, slow-speed, main propulsion diesel engine, which of the parts listed is under tension when the engine is running?（）ABed plateBColumnCEntablatureDTie rod
单选题Critical speeds occurring within the operating speed range of a main propulsion diesel engine may be changed, or have their damaging effects reduced by a/an （）Aengine support vibration isolatorBdetuner or viscous fluid damperClightened crankshaft flywheelDspherically seated crankshaft bearing
单选题If a crankcase explosion occurs in a diesel engine, you should stop the engine and（）Aimmediately open all crankcase relief portsBincrease crankcase exhauster speed to draw cool air into the engineCallow the engine to cool naturallyDincrease crank case scavenge air to remove unburned gases
单选题Critical speed in diesel engines occurs when engine torque pulsations become （）Aopposed to the crankshaft rocking coupleBresonant with the crankshaft natural frequencyCcritical fore and aft crankshaft vibrationsDhorizontal whipping motions of the crankshaft
单选题When used with reversing reduction gears, medium-speed diesel engines should be bolted to their foundations with fitted bolts at the drive end and clearance(loosely fitted) bolts in other locations √This is done to （）Amaintain alignment when the ship’s hull is working in heavy seasBensure engine vibrations correspond to the natural frequency of the hullCpermit the engine to expand away from the driven equipment as the engine heats up and expandsDmaintain engine thrust bearing clearances
单选题After-cooling of a turbocharged diesel engine will result in （）Ahigher torque but lower brake horsepowerBlower torque but higher brake horsepowerChigher torque and lower brake horsepowerDlower torque and higher brake horsepower
单选题If the speed of a turbocharged diesel engine is maintained constant the turbocharger speed will （）Adecrease until the engine speed increasesBincrease as the load increasesCdecrease as the loadDincreases remain unchanged
单选题When comparing different fuels for different engines, the ignition quality of diesel fuel oils becomes a less critical consideration as （）Athe amount of lube oil additives increaseBpiston speeds increaseCinjection pressure decreaseDengine speeds decrease