Exhaust valve openings in a diesel engine cylinder head are made as large as practical to （）

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• （）is harmful for fuel pumps, fuel valves, cylinder liner, exhaust valve seats, and the turbocharger blades as well.

  A . Bad combustion of the fuel B . Bad atomization of the fuel C . Liquid contaminants D . Solid contaminant

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• For an ordinary four-stroke engine the exhaust valves open （）.

  A . after TDC B . before TDC C . after BDC D . before BDC

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• Exhaust temperature increases in all cylinders, the possible cause may be（） (1) increased scavenging air temperature (2) air in fuel pumps and fuel valves (3) fouling of air and gas passages

  A . (1)+(2) B . (1)+(3) C . (2)+(3) D . (1)+(2)+(3)

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• In a four-stroke cycle diesel engine the intake valves open （）

  A . before TDC and close after BDC B . after TDC and close after BDC C . before TDC and close before BDC D . after TDC and close before BDC

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• In some type of two-stroke engines, besides some small holes for（）, starting valve, safety valve, indicator cock, and central opening in each cylinder cover for mounting the（）

  A . fuel valves；exhaust valve B . exhaust valves；inlet valve C . fuel valves；inlet valve D . exhaust valves；fuel valve

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• In its simplest form the pressure reducing valve is opened or closed by （） which is balanced by the downstream pressure acting on a diaphragm.

  A . adjusting a nut B . a pre-tensioned spring C . any spring D . upstream pressure

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• In an engine with air inlet valve and exhaust valve on its cylinder heads the fresh air will enter into the cylinder （） and the gases exhaust （）, there being an adequate overlap between the inlet opening and the exhaust closing.

  A . downwards；upwards B . upwards；downwards C . downwards；downwards D . upwards；upward

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• A two-stroke diesel engine exhaust temperature will be lower than a four-stroke diesel engine of the same displacement because the （） (1) MEP is lower and the scavenging air is cooling the exhaust gases (2) valve overlap in a four-stroke

  A . (1) only is correct B . (2) only is correct C . both (1) and (2) are correct D . Neither (1) or (2) are correct

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• The high-pressure fuel opens the fuel valve and is sprayed into the cylinder in tiny droplets known as （）.

  A . injection B . penetration C . atomization D . compressio

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• If the needle valve in a fuel injection nozzle sticks open （）.

  A . no fuel will be delivered through the nozzle B . the nozzle will overheat and crack C . time of injection will change D . fuel will leak into the drain line

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• Which of the valves listed should be used either in the fully opened or the fully closed position?（）

  A . A gate valve B . A globe valve C . Any check valve D . Any needle valve

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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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• Excessive valve lash in an auxiliary diesel engine will cause the valves to open（）

  A . later and close sooner B . sooner and close later C . sooner and close sooner D . later and close later

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• The opening of an exhaust valve on a modem, large, low-speed, main propulsion diesel engine may be actuated by （）.

  A . direct action of cam shaft B . compressed air pressure C . hydraulic “push rods” D . direct action of the main piston moving dow

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• （） in what position the engine stops there will always be at least one of the cylinders with its starting air valve open to admit compressed air to start the engine.

  A . Because B . Owing to C . For D . No matter

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• A substance found in residual fuels which tends to cause exhaust valve corrosion and grooving, is（）

  A . carbon B . vanadium C . calcium D . hydroge

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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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• In the piping systems of a vessel，what type of valve gives the least resistance to fluid flow when fully open?（）.

  A . Globe valve B . Butterfly valve C . Gate valve D . Packless valve

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• Leaky exhaust valve will result in which of the following?（） (1) high exhaust temperature; (2) low compression pressure; (3) low firing pressure.

  A . (1) and (2) B . (1) only C . (2) only D . (1),(2) and (3)

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• A built-up exhaust valve is one in which （）.

  A . the stem and heads are made of different material B . low-alloy steel is used throughout C . a replaceable valve disk is welded to the head D . the self-centering action comes from motion of the valve stem in the guide

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• In an ordinary four-stroke engine the exhaust valves open （）

  A . after TDC B . before TDC C . after BDC D . before BDC

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• Leaky exhaust valve will result in which of the following？①high exhausttemperature ②low compression ③low firing pressure

  A.① and ② B.② and ③ C.① ② and ③

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• In a turbocharged four-stroke/cycle diesel engine, the exhaust valve remains open until after top dead center and the intake valve opens before top dead center to_______.

  A.produce a scavenging effect in the combustion space B.equalize cylinder and exhaust manifold pressures C.alleviate the difference in valve size between the intake and exhaust D.flush out condensate that collects after each compression stroke

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• The exhaust valve opens before bottom dead center in a four stroke engine to______Iallow for blow down IIReduce pumping losses

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

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