Cast iron pistons used in large propulsion diesel engines are constructed with （）

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• The function of the piston compression rings used in a diesel engine is to （）

  A . seal the space between the piston and liner B . transmit heat from the piston to the cylinder liner C . reduce the amount of combustion gas blow-by D . all of the above

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• If the analysis of used lube oil indicates a high content of iron particles, this could indicate（）

  A . corrosive deterioration of a bearing B . inadequate air filtration C . excessive ring and liner wear D . excessive cooling of lubricating oil

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• （） is sometimes used for piston cooling since leaks into the crankcase would not cause problems.

  A . Diesel oil B . Hydraulic oil C . Lube oil D . Mineral oil

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• Many cast iron pistons are designed with heat dams, which serve to （）

  A . keep piston crown temperatures elevated for smoother combustion B . reduce the possibility of overheating the top compression ring C . help retain the heat of compression to prevent ignition delay D . help retain the heat of compression to prevent combustion knock

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• In order to distribute the side pressures over a wide area of the cylinder walls and liners, which of the listed types of pistons are used in modem low pressure air compressors?（）

  A . Differential B . Trunk C . Barrel D . Valve-in-head

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• An aluminum piston has lower inertia and higher coefficient of （） compared to that of cast iron.

  A . viscosity B . twisting moments C . inertia D . thermal expansio

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• A cast steel strong back is fitted in way of the combustion space to help absorb （）.

  A . flame temperature B . fuel oil C . air movement D . gas force

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• A number of cylinder liners are enclosed in one cast iron casing to form a （）.

  A . cylinder cover B . cylinder block C . cylinder frame D . bed-plate

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• The cast iron（）for the cross-head are attached to the top section and seal off the crankcase.

  A . cylinder cover B . cross-head shoes C . guide-ways D . scavenging boxe

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• An axial piston, variable stroke pump is used in a vessels hydraulic steering gearUnder pressure, oil continually leaks out from between the valve plate/cylinder barrel and will（）.

  A . cause loss of hydraulic oil from the system B . result in extreme damage to the pump C . cause damage to the pump ff not continually drained from the pump casing D . result in the system high side pressure to substantially drop off

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• Ring groove inserts are occasionally used on aluminum alloy piston to（）

  A . reduce the ring groove wear rate B . seal against crankcase vapors C . lessen the wear on aluminum part of the cylinder D . allow for the greater expansion rate of aluminum

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• （） providing lubricating films, oil used in marine diesel engines have to remove heat from oil cooled piston.

  A . Except for B . Beside C . Except D . In addition to

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• Cast iron and gunmetal fittings are used freely in small sizes at moderate pressure; large fittings, those for high pressure and temperature are cast or mild steelIn the above sentence, the word “those” means （）.

  A . east iron firings B . mild steel fittings C . small fittings D . large fitting

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• The usual number of single-acting pistons used in a variable stroke axial-piston pump is （）.

  A、3 or 5 B、5 or 7 C、7 or 9 D、9 or 11

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• An advantage of aluminum pistons, when compared to cast iron pistons is （）.

  A . greater high temperature strength B . better heat conductivity C . greater weight per cubic inch D . increased resistance to wear

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• "Cast iron has poor corrosion resistance to sea water, especially in the presence of bronzes" Implies（）.

  A . east iron is a cheap material B . cast iron can pollute sea water C . cast iron has mere corrosive than bronzes to sea water D . cast iron is more corrosive to sea water when it meets with bronze

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• A tug is “in irons” when held in a fixed position by（）

  A . the weight of its tow，its being anchored，or grounded B . the weight of its towing hawser on the bottom C . an adverse current D . lack of power or an engine breakdow

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• In order to control thermal stresses, some types of modern engines use pistons with（）

  A . heavy wall and intensive cooling B . heavy wall and no cooling C . thin wall and no cooling D . thin wall and intensive cooling

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• Cast irons weakness in tension and under shock loading limits its use to low pressure steam, air, oil and low speed water fittingsThe above sentence, most probably means （）.

  A . cast iron has weakness B . cast iron can stand up shock loading C . cast iron fittings are only suitable in low pressure situation D . east iron fittings are not suitable in low pressure situatio

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• At the top of the A-frames there is a strong cast iron frame called （）.

  A . cylinder liner B . cylinder cover C . the gear box D . the scavenging box

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• which substance in body contains iron?

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• Iron is more useful ______ any other metal.

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• Man’s mind is his tool Of survival.The mind is used to gain，use，store，and recall knowledge.It is his mind that enables a famer t0 know what t0 plant，when to harvest it，how to prepare food from the result.It is his mind that enables a hunter to know what he needs to make a spear，how t0 make it，and how to use it.And it is his mind that enables a blacksmith to know how t0 make iron tools.In short，it i s the mind that enables a person to know what to d0 in order tOosurvive.

  Man’s mind allows long—range planning and thinking.It enables such long—range planning as required for farming，hunting，and tool making.These efforts require the ability to form. concepts of long—term cause and effect chains.“I need t0 make a spear tonight SO I can hunt tomorrow and have food for the next 7 days.”There may be environments where people could survive for a while without long—range planning，but without the results 0f knowledge like spears，fire，and 0ther technologies，people would get out—bred by Other animals and die out。 Man’s mind is his tool for survival，but like all tools，it must be properly used.The mind makes good use 0f knowledge，and knowledge can only be 0btained through reason.Without reason，there is no knowledge，and thus no survival。 You must recognize reality and act in accordance with it in order t0 be successful.To the extent that you use reason as your method of judgment in knowledge and action，you will survive and flourish .If you ignore or escape form. reality you will suffer and die. It is very important t0 note that survival by reason requires the freedom to act according t0 your reason.That is why people d0 not develop well in the control of others，and can not survive when they are subject t0 foree that destroys their ability to act on reason. 26.It is his mind that enables a farmer t0 know how to_______. A.make spears B.hunt for animals C.make iron tools D.cultivate crops 27.The first two paragraphs show that man’s mind______. A. is his basic means Of survival B. enables him to act at will C. is used to protect themselves D. helps him 100k int0 reality 28. In order to survive，man should_______. A.be conquered by 0thel"allimals B.make a long—range plan for the future C.1earn to recall knowledge D.1earn to think reasonably 29.Without the results Of knowledge like spears，fire，and Other technologies，people_____. A.Could only survive for7 days B.would kill off a11 the animals C.would be controlled by 0thers D.would disappear from the earth 30.It is reasonable that if people want to survive，they should______. A.develop well in the control of others B.ignore or escape from reality C.have freedom to act on reason D.be subject to certain environments

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• When carbon is added to iron in proper__, the result is steel（）

  A．rates B．thicknesses C．proportions D．densities

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