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单选题
The satisfactory operation of diesel engine exhaust valves usually depends on（）
A
the proper back pressure
B
the cooling water temperature
C
correct timing and proper seating
D
accurate metering and the exhaust temperature
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单选题For an ordinary four-stroke diesel engine the exhaust valves close （）.A
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principleB
principalC
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cylindersB
exhaust valvesC
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单选题Air scavenging of a diesel engine cylinder（）A
blows out the exhaust gasesB
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单选题In a diesel engine, exhaust valves open before the intake ports are uncovered to （） Ⅰ.reduce pumping losses Ⅱ.reduce back pressureA
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单选题Diesel engine mufflers or silencers reduce the engine exhaust noise by （）A
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diffusing exhaust vibrations through activated carbon bafflesC
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reducing the exhaust gas velocity
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单选题If the jacket water temperature in an auxiliary diesel engine cooling system is lower than normal, the probable cause is （）A
air binding of the engine cooling systemB
a cracked water cooled exhaust manifoldC
blockage in the heat exchangerD
faulty operation of the thermostat
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单选题Clogged or partially obstructed exhaust ports on a diesel engine can cause（）A
over-speeding of the engineB
failure of the engine to shut downC
no effect of engine mounting boltsD
high exhaust temperatures
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单选题Diesel engine exhaust noise can be reduced in an exhaust muffler by （）A
changing the direction of exhaust gas flowB
increasing the exhaust gas velocityC
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increasing the exhaust gas static pressure
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单选题The exhaust system of a diesel engine is usually designed to remove exhaust gases and to （）A
provide exhaust back pressureB
prevent exhaust smoke emissionsC
power a reciprocating superchargerD
muffle exhaust gas noise
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单选题The loss of the diesel engine cylinder air charge through leaky valves, piston rings, worn or scored liners, would be indicated by which of the following sets of conditions?（）A
Low compression pressure and high exhaust temperatureB
Low firing pressure and high exhaust temperatureC
Low compression pressure and low exhaust temperatureD
Low firing pressure and low exhaust temperature
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单选题When would the available energy of the exhaust gases of a two-stroke/cycle diesel engine be insufficient to drive an exhaust gas turbocharger, resulting in the incorrect amount of air for combustion?（）A
During operation at low speedB
During operation at rated speed, but low power outputC
During accelerationD
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Blank off the exhaust gas inlet to the damaged turbochargerB
Secure cooling and lubrication to the damaged turbochargerC
Lock the rotor of the damaged turbochargerD
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单选题What is the purpose of the intake/exhaust valves in a diesel engine? （）A
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They supply cooling waterC
They synchronize the ignition sparkD
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单选题In a diesel engine exhaust system, the cooling of the exhaust gases below their dew point, will result in （）A
increased engine back pressureB
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单选题Which of the following conditions can cause above normal air temperature to develop in the intake manifold of a four-stroke/cycle turbo-charged diesel engine?（）A
Clogged air intake faltersB
Piston blow-byC
A defective after-coolerD
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考题
单选题Low compression pressure in a diesel engine may be the result of （）A
insufficient fuel supply due to fuel pump valves sticking or leakingB
excessive mechanical clearance between the piston crown and cylinder headC
excessively worn fuel pump plungerD
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考题
单选题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 seatingB
intake valves utilize stellite-coated valve seat inserts which reduce wearC
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intake valves are less affected to the corrosive action of exhaust gases
考题
单选题If you observe smoke coming from the turbocharger of an auxiliary diesel engine, you should（）A
check the air filter for obstructionB
check for an exhaust leakC
check the exhaust temperatureD
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单选题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 springsB
compressed air pressureC
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单选题“This increase in charge air density is accomplished on most modern diesel engine types by use of exhaust gas turbo-charging, in which a turbine wheel driven by exhaust from the engine is rigidly coupled to a centrifugal type air compressor” According to this sentence, we can know that increases density（）, drives the compressor directly（）A
a modern diesel engine；a turbine wheelB
a modem diesel engine；exhaust gasesC
a compressor；an exhaust gas turbochargerD
a compressor；a turbine wheel
考题
单选题A two-stroke diesel engine exhaust temperature will be lower than a four-stroke diesel engine of the same displacement because the （） (1) scavenging air is cooling the exhaust gases (2) exhaust cycle time is longerA
(1) onlyB
(2) onlyC
both (1) and (2)D
neither (1) nor (2)
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