[单项选择]In comparison to exhaust valves, intake valves of diesel engines may be fabricated from low alloy steels because （）.
A. the beveled edges of the intake valves provide for serf-centering during seating
B. intake valves utilize stellite-coated valve seat inserts which reduce wear
C. the volume of air passing through intake valves is less than the volume of air passing through exhaust valves
D. intake valves are less affected to the corrosive action of exhaust gases

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[单项选择]What is the purpose of the intake/exhaust valves in a diesel engine? （）
A. They regulate the combustion cycle
B. They supply cooling water
C. They synchronize the ignition spark
D. They supply and regulate the lubricant flow

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[单项选择]Many diesel engine exhaust valves are being constructed with hollow stems filled with sodium in order to （）
A. provide added wear protection against today’s corrosive quality of fuel
B. increase overall valve strength due to the high gas pressures
C. assist in dissipating heat due to the extreme operating temperatures
D. reduce the overall weight of the valve thus helping eliminate valve spring surge and hammering

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In a diesel engine, exhaust valves open before the intake ports are uncovered to （）
Ⅰ.reduce pumping losses
Ⅱ.reduce back pressure

A. Ⅰonly
B. Ⅱonly
C. bothⅠand Ⅱ
D. neitherⅠnor Ⅱ

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[单项选择]The closing of the exhaust valves used on a modern, large, low-speed, main propulsion diesel engine may be directly provided by （）.
A. large conical springs
B. compressed air pressure
C. hydraulic pressure
D. exhaust gas pressure

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[单项选择]The intake valves in a diesel engine are reseated by （）.
A. cam followers
B. push rods
C. combustion gases
D. valve springs

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[单项选择]The period when both inlet valves and exhaust valves are open is referred to as （）.
A. valve loop
B. valve uniflow
C. valve overlap
D. valve grinding

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[单项选择]Additional heat extraction from the exhaust gases can be effected by adding an （） section to the unit in plants.
A. air cooler
B. economizer
C. injector
D. air blower

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[单项选择]High exhaust temperature and black smoke exhausting from an auxiliary diesel engine can be caused by （）.
A. engine overload
B. low combustion temperature
C. plugged fuel nozzle holes
D. excessive compression pressure

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[单项选择]Pyrometers commonly found on diesel engine exhaust systems, consist of（）
A. pyrostats and a voltmeter
B. a gas-filled bellows, a tube and a pressure gauge
C. thermocouples and a voltmeter
D. ammeters and thermocouples

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[单项选择]Exhaust pyrometer readings provide an indication of the （）
A. effectiveness of water-cooled exhaust elbows
B. distribution of the load between engine cylinders
C. amount of fuel penetration into the engine cylinders
D. indicated horsepower of the engine cylinders

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[单项选择]Intake air flow from a diesel engine turbocharger is directly proportional to engine（）
A. exhaust gas pressure
B. exhaust gas temperature
C. speed
D. load

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[单项选择]Worn diesel engine intake valve guides can result in （）
A. increased engine breathing efficiency
B. excessive valve lash
C. excessive lube oil consumption
D. lower than normal fuel consumption

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[单项选择]Directional intake ports in diesel engines are used to （）.
A. reduce air charge turbulence
B. induce air swirl
C. deflect hot combustion gas away from the valves
D. oppose the effects of piston induced squish

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[单项选择]The rising of the exhaust temperature in manifold pipe may NOT result from （）.
A. too great a loading
B. fouled turbocharger
C. bad combustion
D. excessive air

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The exhaust valve opens before bottom dead center in a four stroke engine to（）
Ⅰ.allow for blow down
Ⅱ.Reduce pumping losses

A. Ⅰ only
B. Ⅱ only
C. both Ⅰ and Ⅱ
D. neither Ⅰ nor Ⅱ

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[单项选择]The mechanical exhaust valve operation system is replaced by（）in an electronic controlled ME engine.
A. a system with a Hydraulic Power Supply (HPS) unit
B. a system with roller guides for exhaust valves
C. a system with an electronically controlled Alpha Lubricator
D. a system directly powered by electric motor

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[单项选择]A smoking exhaust from an operating diesel engine could be caused by （）
A. low sulfur content in the fuel
B. a loose injector inlet connection
C. late fuel injection
D. high injection pressure

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[单项选择]Icreasing the exhaust valve tappet clearance of a diesel engine will result in the exhaust valve opening （）
A. later and closing earlier
B. later and closing later
C. earlier and closing earlier
D. earlier and closing later

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[单项选择]Exhaust gases are generally removed from the cylinders of a two-stroke/cycle diesel engine by（）
A. natural aspiration
B. masked intake valves
C. air cells
D. scavenging air

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