网友您好， 请在下方输入框内输入要搜索的题目：
题目内容
（请给出正确答案）
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
lead
B
forged steel
C
alloy steel
D
aluminum alloy
参考答案
参考解析
解析：
暂无解析
更多 “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” 相关考题
考题
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
考题
To reduce the weight of the reciprocating parts, pistons of high-speed engines are made considerably shorterThis results in __________.A.less piston slap and quieter runningB.increased crankshaft bearing wearC.slightly greater piston wearD.decreased side pressures
考题
单选题One major disadvantage of a low-speed diesel as compared to a steam main-propulsion system is（）.A
the extra weight required for the diesel reduction gearingB
a minimum speed for the engines that limits the minimum speed of the vesselC
the higher fuel consumption per SHPD
the low efficiency of the system when a controllable pitch propeller is used
考题
单选题（）are increasingly used as main engine on merchant vessels, because they have a high Hp/Weight ratio.A
Slow speed diesel enginesB
Medium-speed diesel enginesC
Steam enginesD
Gasoline engines
考题
单选题The over-speed trip device installed in some diesel engines is automatically actuated by（）A
spring forceB
hydraulic pressureC
centrifugal forceD
mechanical linkage
考题
单选题To reduce the weight of the reciprocating parts, pistons of high-speed engines are made considerably shorterThis results in （）A
less piston slap and quieter runningB
increased crankshaft bearing wearC
slightly greater piston wearD
decreased side pressures
考题
单选题On most diesel engines, the governor controls the output speed by （）.A
controlling the amount of fuel injected into the cylindersB
varying the speed of the turbochargerC
adjusting the compression ratioD
changing the timing of the fuel injection camshaft
考题
单选题Typical marine propulsion plants include（） directly coupled to the vessel’s single large-diameter, fixed-pitch propeller.A
a single, long-stroke, slow-speed, turbocharged, two-stroke diesel engineB
a single, long-stroke, medium-speed, turbocharged, four-stroke diesel engineC
two medium-speed, turbocharged, four-stroke diesel enginesD
a variable-speed AC generator
考题
单选题Pistons may be made in （） in order to keep the weight down for balancing purposes at high speed.A
cast ironB
forged steelC
stainless steelD
aluminum alloy
考题
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
purity
考题
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
考题
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
考题
单选题Medium speed engines have a （） power to weight ratio than the slow speed two strokes, but due to the higher speeds tend to have （） maintenance intervals.A
higher；reducedB
higher；increasedC
lower；reducedD
lower；increased
考题
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
考题
单选题Marine four-stroke diesel engines are mainly （）.A
of crosshead typeB
of trunk piston typeC
of low speed typeD
all the above
考题
单选题Diesel engines are considered safer than gasoline engines because（）.A
they are more heavily builtB
the fuel used is less volatileC
they can be easily reversedD
they operate at a lower speed
考题
单选题Before a marine diesel engine is started the cylinders and pistons must be （）.A
cooled to appropriate temperatureB
warmed up gradually to appropriate temperatureC
opened up and renewedD
ground and polished
考题
单选题The following preparations are essential for any （） of marine diesel engine before it may be started.A
doingB
makeC
turnD
operating
考题
单选题Cylinders of marine diesel engines are normally cooled by （）.A
sea waterB
fine mineral oilC
sanitary waterD
fresh water
考题
单选题The reason why more and more of the large merchant vessels are being powered by medium-speed diesel engines is （）.A
they operate between 150 and 450 rpmB
they are connected to the propeller by gearingC
their smaller size and weightD
they can be connected directly to the propeller without gearing
考题
单选题Some medium and high-speed diesel engines require reduction gear units to provide a useful propeller speedIn most reduction gears, the bull gear（）A
must churn the oil in the sumpB
is connected to the propeller shaftC
is driven at the highest RPMD
compensates for alignment variations between the engine and pinion gear
考题
单选题（）diesel engines generally have two systems of lubrication:（）a total loss system feeding and a circulating system lubricating the running gear and cooling the pistons.A
Large crosshead type；crossheadsB
High speed；the cylindersC
Large crosshead type；the cylindersD
Four-stroke；pistons and cylinders
考题
单选题Crankshafts of medium speed engines are （） from a single piece of steel.A
unusually solid weldedB
never be solid forgedC
almost invariably solid forgedD
almost invariably be welded
考题
单选题The crankshafts of medium speed engines are almost invariably solid （） from a single piece of steel.A
forgedB
castC
madeD
shrunk
考题
单选题Although the crankshafts of medium diesel engines appear to be robust, they rely on the support of （） to develop their full strength.A
the piston rodsB
the crank throwsC
the thrust bearingsD
the main bearings
考题
单选题（） providing lubricating films, oil used in marine diesel engines have to remove heat from oil cooled piston.A
Except forB
BesideC
ExceptD
In addition to
考题
单选题Prior to starting most medium-speed propulsion diesel engines, which of the procedures listed should be observed?（）A
The expansion tank should be topped offB
The thermostatic water regulating valves should be manually openedC
The fuel filters should be changedD
The engine should be turned over slowly with the indicator cocks open
考题
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
热门标签
最新试卷