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Each cylinder liner on the marine medium speed engines _____.
A.is usually cooled by sea water
B.can be replaced when worn out
C.is in direct contact with the water in the bore of the cylinder
D.can t expand when heated
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更多 “ Each cylinder liner on the marine medium speed engines _____.A.is usually cooled by sea waterB.can be replaced when worn outC.is in direct contact with the water in the bore of the cylinderD.can t expand when heated ” 相关考题
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When water( ), it will be changed into vapour.A. is heatedB. was heatedC. will be heatedD. would heated
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A crack in a cylinder liner can be caused byA.worn piston ringsB.installation of undersized sealing ringsC.operating the engine at low loadsD.restricted cooling water passages
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Low compression in a diesel engine could be caused byA.worn or broken cylinder liner sealing ringsB.high cooling water temperatureC.worn or broken piston ringsD.low fuel oil pressure
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第一组Older loop scavenged engines may have a single injector mounted centrally in the cylinder head. Because the exhaust valve is in the center of the cylinder head on modern uniflow scavenged engines the fuel valves (2 or 3) are arranged around the periphery of the head. The pressure at which the injector operates can be adjusted by adjusting the loading on the spring. The pressures at which the injectors operate vary depending on the engine, but can be as high as 540 bar. Some injectors have internal cooling passages in them extending into the nozzle through which cooling water is circulated. This is to prevent overheating and burning of the nozzle tip. Injectors on modern engines do not have internal cooling passages. They are cooled by a combination of the intensive bore cooling in the cylinder head being close to the valve pockets and by the fuel which is re-circulated through the injector when the follower is on the base of the cam or when the engine is stopped. As well as cooling the injector, re-circulating the fuel when the engine is stopped keeps the fuel at the correct viscosity for injection by preventing it from cooling down. Fuel injectors must be kept in good condition to maintain optimum efficiency, and to prevent conditions arising which could lead to damage within the cylinder. Injectors should be changed in line with manufacturers recommendations, overhauled and tested. Springs can weaken with repeated operation leading to the injector opening at a lower pressure than designed. The needle valve and seat can wear which together with worn nozzle holes will lead to incorrect atomization and dribbling.Modern uniflow scavenged engines have______.A.a single injector mounted in the center of the cylinder headB.several injectors mounted around the external boundary of the cylinder headC.a single injector mounted at the external boundary of the cylinder headD.several injectors mounted in the center of the cylinder head
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Cylinders of marine diesel engines are normally cooled by ___ .A.sea waterB.fine mineral oilC.sanitary waterD.fresh water
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单选题Insufficient end clearance on newly fitted piston rings in a diesel enginewill cause the rings to（）A
jam in the most worn part of the cylinder when the rings expandB
break in the most worn part of the cylinder when the rings expandC
wear eccentrically on the side opposite the end gapD
overheat and jam at the top center on the combustion stroke
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单选题In large marine diesel engines cylinder oils usually contain additives formulated to impart the （） to clean the rings and grooves.A
inefficiencyB
oilinessC
detergencyD
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单选题What is the operating principal of a flash type evaporator?（）A
Sea water is heated to boiling temperature under a vacuumB
Sea water is passed over heated plates in a thin filmC
Heated sea water is injected into a vacuum chamberD
Sea water is forced through a heated eductor
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单选题Each cylinder liner on the marine medium speed engines （）.A
is usually cooled by sea waterB
can be replaced when worn outC
is in direct contact with the water in the bore of the cylinderD
can t expand when heated
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单选题In a medium speed diesel engine, a trunk type piston may be cooled by（） Ⅰ.oil circulation though passages in the piston crown Ⅱ.heat transfer through piston rings and liner wallA
Ⅰ onlyB
Ⅱ onlyC
either Ⅰ or ⅡD
neither Ⅰ or Ⅱ
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单选题The majority of medium speed and high speed marine diesel engines for main or auxiliary drive operate on the （） cycle.A
two-strokeB
four-stokeC
long-strokeD
short-stroke
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单选题Injectors on modern engines are cooled by a combination of the intensive bore cooling in the cylinder by a combination of the intensive bore pockets and by the fuel which is re-circulated through the injector when the follower is on the （）of the cam or when the engine is stopped.A
slopeB
baseC
topD
bottom
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单选题The cylinder liner forming the cylinder wall and the inside of the water jacket is called a（）A
dry linerB
wet linerC
jacket linerD
corrugated liner
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单选题Cylinders of marine diesel engines are normally cooled by （）.A
sea waterB
fine mineral oilC
sanitary waterD
fresh water
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单选题Which of the following statements is correct concerning diesel engine cooling water systems?（）A
Each engine must have its own engine driven cooling water pump capable of providing cooling for all ranges of operationB
propulsion engines with bores exceeding 200 mm are to be fitted with a means to display the cooling water temperature of each cylinderC
At least two independent sea suctions are to be provided for supplying water to the engine jackets or to the heat exchangersD
Suitable strain are to be fitted between the circulating pumps and heat exchangers when sea water is used for direct cooling
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单选题When used with reversing reduction gears, medium-speed diesel engines should be bolted to their foundations with fitted bolts at the drive end and clearance(loosely fitted) bolts in other locations √This is done to （）A
maintain alignment when the ship’s hull is working in heavy seasB
ensure engine vibrations correspond to the natural frequency of the hullC
permit the engine to expand away from the driven equipment as the engine heats up and expandsD
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单选题Allowance for fresh water refers to（）.A
the provision to be provided when the vessel sails in fresh water areaB
the fresh water to be carried by a vesselC
the allowance of fresh water for each crew member when in distress at seaD
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单选题When good and steady service conditions have been achieved, the running surfaces of the piston rings and cylinder liner will be（）In addition, the rings will move freely in the grooves and also be well oiled intact, and not unduly worn.A
hazy lightB
hazy light brownC
hazy light blueD
hazy light grey
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单选题Which of the following procedures should be carried out when a large, low-speed, diesel engine is operated with one cylinder secured?（）A
Lubrication to the defective cylinder should be increasedB
Cooling water temperature to the engine should be increasedC
Only the turbocharger speed should be reducedD
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单选题The bore of each cylinder is formed in a liner which can be （） when worn out.A
weldedB
replacedC
drilled againD
bored
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单选题Cooling water pumps driven by direct reversing diesel engines are usually of the straight impeller vane type pump with a concentric housing to（）A
facilitate bi-directional operationB
provide the greatest pump efficiencyC
prevent pump clogging from marine growthD
prevent cavitation at the pump outlet
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单选题Trunk type diesel engine pistons are effectively cooled when heat is（）A
radiated through the engine blockB
transferred to water cooled cylinder wallsC
conducted through the piston crownD
transferred to escaping exhaust gases
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单选题Pistons of marine medium speed diesel engines may be made of （） in order to keep the weight down for balancing purpose at high speed.A
leadB
forged steelC
alloy steelD
aluminum alloy
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单选题The cooling water is in direct contact with the outer surface of the liner as a result of which it is termed a （）.A
water linerB
wet linerC
dry linerD
drown liner
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单选题Cylinder lubrication oil for low speed main propulsion diesel engines is admitted to each cylinder during （）.A
the power strokeB
the compression strokeC
low load operation onlyD
periods of standby
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单选题The rate of cylinder lubricating oil metered to each cylinder of a large low-speed main propulsion diesel engine is （）A
the same, whether at sea, or during maneuveringB
adjusted during each hour of operation while at constant RPMC
higher at sea than while maneuveringD
lower at sea than while maneuvering
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