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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
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单选题（）are increasingly used as main engine on merchant vessels, because they have a high Hp/Weight ratio.A
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考题
单选题An over-speed trip stops a diesel engine when the engine （）A
runs out of fuelB
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moving the governor control to stopB
shutting off the lubricating oil supplyC
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单选题A diesel engine which is rated for normal operation at a crankshaft speed of 800 RPM, is commonly classed as a （）.A
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medium-speed dieselC
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考题
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（）.A
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caused by a mechanical defect in one cylinderC
caused by high fuel injection pressuresD
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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?（）A
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单选题The main function of tie rods in the construction of large, low speed diesel engines is to（）.A
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考题
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?（）A
Bed plateB
ColumnC
EntablatureD
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考题
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 （）A
engine support vibration isolatorB
detuner or viscous fluid damperC
lightened crankshaft flywheelD
spherically seated crankshaft bearing
考题
单选题If a crankcase explosion occurs in a diesel engine, you should stop the engine and（）A
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考题
单选题Critical speed in diesel engines occurs when engine torque pulsations become （）A
opposed to the crankshaft rocking coupleB
resonant with the crankshaft natural frequencyC
critical fore and aft crankshaft vibrationsD
horizontal whipping motions of the crankshaft
考题
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 （）A
maintain alignment when the ship’s hull is working in heavy seasB
ensure engine vibrations correspond to the natural frequency of the hullC
permit the engine to expand away from the driven equipment as the engine heats up and expandsD
maintain engine thrust bearing clearances
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单选题After-cooling of a turbocharged diesel engine will result in （）A
higher torque but lower brake horsepowerB
lower torque but higher brake horsepowerC
higher torque and lower brake horsepowerD
lower torque and higher brake horsepower
考题
单选题If the speed of a turbocharged diesel engine is maintained constant the turbocharger speed will （）A
decrease until the engine speed increasesB
increase as the load increasesC
decrease as the loadD
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考题
单选题When comparing different fuels for different engines, the ignition quality of diesel fuel oils becomes a less critical consideration as （）A
the amount of lube oil additives increaseB
piston speeds increaseC
injection pressure decreaseD
engine speeds decrease
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