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
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
相关考题：
When water( ), it will be changed into vapour.A. is heatedB. was heatedC. will be heatedD. would heated
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
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
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
Cylinders of marine diesel engines are normally cooled by ___ .A.sea waterB.fine mineral oilC.sanitary waterD.fresh water
单选题Insufficient end clearance on newly fitted piston rings in a diesel enginewill cause the rings to（）Ajam in the most worn part of the cylinder when the rings expandBbreak in the most worn part of the cylinder when the rings expandCwear eccentrically on the side opposite the end gapDoverheat and jam at the top center on the combustion stroke
单选题In large marine diesel engines cylinder oils usually contain additives formulated to impart the （） to clean the rings and grooves.AinefficiencyBoilinessCdetergencyDpurity
单选题What is the operating principal of a flash type evaporator?（）ASea water is heated to boiling temperature under a vacuumBSea water is passed over heated plates in a thin filmCHeated sea water is injected into a vacuum chamberDSea water is forced through a heated eductor
单选题Each cylinder liner on the marine medium speed engines （）.Ais usually cooled by sea waterBcan be replaced when worn outCis in direct contact with the water in the bore of the cylinderDcan t expand when heated
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 wallAⅠ onlyBⅡ onlyCeither Ⅰ or ⅡDneither Ⅰ or Ⅱ
单选题The majority of medium speed and high speed marine diesel engines for main or auxiliary drive operate on the （） cycle.Atwo-strokeBfour-stokeClong-strokeDshort-stroke
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.AslopeBbaseCtopDbottom
单选题The cylinder liner forming the cylinder wall and the inside of the water jacket is called a（）Adry linerBwet linerCjacket linerDcorrugated liner
单选题Cylinders of marine diesel engines are normally cooled by （）.Asea waterBfine mineral oilCsanitary waterDfresh water
单选题Which of the following statements is correct concerning diesel engine cooling water systems?（）AEach engine must have its own engine driven cooling water pump capable of providing cooling for all ranges of operationBpropulsion engines with bores exceeding 200 mm are to be fitted with a means to display the cooling water temperature of each cylinderCAt least two independent sea suctions are to be provided for supplying water to the engine jackets or to the heat exchangersDSuitable strain are to be fitted between the circulating pumps and heat exchangers when sea water is used for direct cooling
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 （）Amaintain alignment when the ship’s hull is working in heavy seasBensure engine vibrations correspond to the natural frequency of the hullCpermit the engine to expand away from the driven equipment as the engine heats up and expandsDmaintain engine thrust bearing clearances
单选题Allowance for fresh water refers to（）.Athe provision to be provided when the vessel sails in fresh water areaBthe fresh water to be carried by a vesselCthe allowance of fresh water for each crew member when in distress at seaDthe amount of free board decreased when sailing in fresh water area
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.Ahazy lightBhazy light brownChazy light blueDhazy light grey
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?（）ALubrication to the defective cylinder should be increasedBCooling water temperature to the engine should be increasedCOnly the turbocharger speed should be reducedDEngine speed should be reduced
单选题The bore of each cylinder is formed in a liner which can be （） when worn out.AweldedBreplacedCdrilled againDbored
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（）Afacilitate bi-directional operationBprovide the greatest pump efficiencyCprevent pump clogging from marine growthDprevent cavitation at the pump outlet
单选题Trunk type diesel engine pistons are effectively cooled when heat is（）Aradiated through the engine blockBtransferred to water cooled cylinder wallsCconducted through the piston crownDtransferred to escaping exhaust gases
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.AleadBforged steelCalloy steelDaluminum alloy
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 （）.Awater linerBwet linerCdry linerDdrown liner
单选题Cylinder lubrication oil for low speed main propulsion diesel engines is admitted to each cylinder during （）.Athe power strokeBthe compression strokeClow load operation onlyDperiods of standby
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