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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 light
B . hazy light brown
C . hazy light blue
D . hazy light grey
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If the back clearance of a piston ring is excessive,（）
A . compression pressure in the cylinder will be higher
B . carbon will accumulate behind the ring
C . combustion gases will penetrate beneath the ring land
D . piston side thrust will be increased
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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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In a diesel engine, when refitting piston rings you should （） Ⅰ.check the ring gap at the smallest diameter of the cylinder Ⅱ. Remove carbon from the ring groove
A . Ⅰ only
B . Ⅱ only
C . both Ⅰ and Ⅱ
D . neither Ⅰ nor Ⅱ
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In the sentence “In some designs the cylinder oil is timed so that the oil injects only on the piston ring belt, the "piston ring belt" means （）.
A . piston crown
B . piston ring groove
C . piston skirt
D . piston ring area
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In large marine diesel engines cylinder oils usually contain additives formulated to impart the （） to clean the rings and grooves.
A . inefficiency
B . oiliness
C . detergency
D . purity
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Broken piston rings manifest themselves during the scavenge port inspection by（）
A . Lack of elastic tension, when the rings are pressed into the groove by means of a stick
B . Blackish appearance
C . Fractured rings and missing rings
D . all off the above
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The piston rings are manufactured with a diameter （） the bore of the cylinder.
A . larger than
B . smaller than
C . equal to
D . none of the above
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If the piston groove drain holes for the oil control rings become clogged, which of the following is likely to occur?（）
A . The oil control rings will seal improperly and wear rapidly
B . The piston will overheat due to insufficient lubrication
C . Excessive oil will remain on the cylinder wall
D . Light brown smoke will emanate from the engine exhaust
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The main purpose of the piston oil scraper rings is to （）.
A . seal the space between the piston and the liner
B . reduce the amount of lube oil burned in the combustion chamber
C . transmit heat from the piston to the cylinder liner
D . damp out fluctuations of the piston side thrust
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A condition contributing to diesel engine piston rings sticking in the ring grooves, is insufficient ring clearance at the ring（） Ⅰ.gap Ⅱ.side
A . Ⅰonly
B . Ⅱ only
C . both Ⅰ and Ⅱ
D . neither Ⅰ nor Ⅱ
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In a diesel engine, excessive cylinder liner wear will cause （） (1) increased blow-by (2) wear between the piston ring and groove
A . (1) only is correct
B . (2) only is correct
C . both (1) and (2) are correct
D . neither (1) or (2) axe correct
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（） neutralizes the acid conditions and（） cleanses the rings and grooves.
A . The detergency；the alkalinity
B . The alkalinity；the detergency
C . The inhabitant；the water
D . The additives；the distilled water
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The sealing function of the piston ring is brought about by the gas pressure above and behind the piston ring, which forces it （） against the bottom of the ring groove, and （） against the cylinder wall.
A . upwards；inwards
B . upwards；outwards
C . downwards；inwards
D . downwards；outward
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When installing rings on a diesel engine piston, you should check the ring（）
A . diametrical tension
B . gap clearance
C . radial thickness
D . face thickne
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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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If the piston ring gap remains insufficient when installing new rings, youshould（）
A . install oversized rings
B . hone the cylinder liner to allow ring installation
C . compress the rings tighter with a compressing tool
D . file the ends of the ring
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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 expand
B . break in the most worn part of the cylinder when the rings expand
C . wear eccentrically on the side opposite the end gap
D . overheat and jam at the top center on the combustion stroke
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If the compression rings on a diesel engine piston become stuck in the ring groove, the cause may be due to（）
A . excessive ring action
B . excessive ring temperature
C . improper ring rotation
D . excessive ring face wear
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The piston rings if found worn out （） and supplied by shipchandler.
A . must replace
B . must to be equipped
C . has to be repaired
D . have to be renewed
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The main function of piston compression rings is to （）
A . prevent excessive cylinder liner wear
B . reduce friction losses in the engine
C . seal the space between the piston and the liner
D . limit upward flow of lube oil into the combustion space
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Diesel engine piston ring blow-by is usually caused by excessive ring clearance at the ring（）
A . back
B . side
C . gap
D . bottom
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The lowest ring of a piston is （）.
A . a coil spring
B . a sealing ring
C . an oil distributor ring
D . main seal ring
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Black areas on the sealing surfaces of piston rings indicate＿.
A.lube oil pumping
B.rotating rings
C.gas pressure behind the ring
D.passage of hot gases
