Abnormal crankpin bearing and piston s...

单项选择题Abnormal crankpin bearing and piston skirt surface wear indicate（）

A.a restricted air intake
B.a clogged connecting rod oil passage
C.incorrect connecting rod alignment
D.high cylinder firing temperatures

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1.单项选择题Injection lag in a diesel engine may be caused by（）

A.a higher cetane number of fuel oil
B.the diesel fuel used having a high viscosity
C.mechanical rigidity in the lube pump mechanism
D.a decrease rigidity in the fuel pump delivery pressure

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2.单项选择题Which of the following relationships should occur between the temperature developed in a combustion space, and the compression ratio of the engine?（）

A.Higher compression ratios create higher temperature
B.Higher temperatures create higher compression ratios
C.low temperatures create higher compression ratios
D.Higher compression ratios create low temperatures

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3.单项选择题An acceptable method of measuring for the correct rotational force applied to the connecting rod and main bearing bolts, is to use a（）

A.torque wrench
B.monkey wrench
C.pipe wrench
D.slugging wrench

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4.单项选择题Which of the listed types of starting systems is often used on large, low-speed, direct reversing, main propulsion diesel engines?（）

A.Electric
B.Hydraulic
C.Air
D.All of the above

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5.单项选择题In a large, low-speed diesel engine the clearance between the piston crown and cylinder head is found to be excessiveIn order to correct for this, you should（）

A.build up the piston crown by metal spraying
B.build up the cylinder head by metal spraying
C.insert shims between the crankpin bearing box and the connecting rod foot
D.install a thinner head gasket

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6.单项选择题A mixture of 45%cetane and 55% alpha-methyl-naphthalene is found to have the same ignition delay as a sample of diesel oil √The sample can be described as having a/an（）

A.cetane number of 55
B.cetane number of 45
C.octane number of 55
D.octane number of 45

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7.单项选择题Worn main bearing will cause the compression ratio of an auxiliary diesel engine to（）

A.increase
B.decrease
C.remain the same
D.increase on compression decrease on expansion

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8.单项选择题With respect to diesel fuel, the ease with which a cold engine will start is dependent upon the（）

A.ignition quality of the fuel
B.high heating value of the fuel
C.amount of carbon residue after combustion
D.internal flow resistance in the injectors

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9.单项选择题A two-stroke/cycle diesel engine requires less starting air than a four-stroke/cycle diesel engine, of equal displacement, because the two-stroke/cycle diesel engine（）

A.has little or no internal friction
B.has a lower effective compression ratio
C.operates with scavenge air under a positive pressure
D.operates without energy absorbing intake and exhaust strokes

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10.单项选择题Which of the following operating conditions can occur when shims are removed from the joint between the foot of a marine type diesel engine connecting rod and the bearing box?（）

A.Decreased connecting rod bearing clearance
B.Increased connecting rod bearing clearance
C.Decreased compression ratio
D.Increased compression ratio

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