單項選擇題The expansion tank for a diesel engine closed cooling system is designed to maintain a constant head on the system and （）.

A.reduce water temperature
B.reduce water turbulence
C.provide an air cushion
D.allow for an increase in water volume as the engine warms up


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1.單項選擇題For a continuous operation diesel engine, a duplex filter unit would be the best arrangement because （）.

A.changing filter elements would not interrupt engine operation
B.filtering occurs twice in each pass of oil through the system
C.clogging will not occur
D.dropping pressure is half of that through a single filter unit

2.單項選擇題An increase in the air inlet manifold pressure of a diesel engine will result in a/an （）.

A.decrease in maximum cylinder pressure
B.increase in ignition lag
C.decrease in fuel consumption per horsepower-hour
D.decrease in exhaust manifold pressure

3.單項選擇題The overspeeding of the diesel engine driving an electric generator could cause （）.

A.low voltage trip to trip
B.reverse power trip to trip
C.damage to windings
D.excessive exhaust temperatures

4.單項選擇題During the fuel injection period, fuel pressure must exceed cylinder gas pressure to （）.

A.ensure penetration and distribution of the fuel in the combustion chamber
B.ensure the needle valve is flushed clean during each injection
C.prevent combustion gas blowback into the open needle valve
D.prevent reflected pressure waves when the needle valve closes

5.單項選擇題A naturally aspirated diesel engine at full throttle will have an intake manifold pressure （）

A.slightly less than atmospheric pressure
B.approximately equal to exhaust manifold pressure at all times
C.that is widely fluctuating constantly
D.decreasing as engine load increases