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
相似题目
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The lower section of a piston is called the （）.
A . land
B . skirt
C . crown
D . plate
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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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While engine is in operation the piston moves up and down, thus causing the rotation of the （）.
A . crankcase
B . slipper
C . cam housing
D . crankshaft
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Which of the following characteristic of lube oil helps to reduce the amount of deposits in the piston ring belt during the combustion process in a diesel engine?（）
A . Low viscosity index
B . Low carbon forming tendencies
C . High film strength
D . High non-corrosive qualitie
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The lower end of each piston rod is reduced in diameter to fit a bore in the （）, this being secured to the piston rod by a nut.
A . piston gudgeon pin
B . piston skirt
C . cross-head
D . cross-head pi
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The delivery rate of an axial-piston hydraulic pump is controlled by varying the position of the （）.
A . sliding block
B . pintle
C . reaction ring
D . tilting box or swash plate
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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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To function properly, oil control rings used on a diesel engine piston must distribute sufficient oil to all parts of the cylinder wall and must also（）.
A . prevent any lubricant from reaching
B . prevent excessive lubrication from reaching the combustion space
C . Provide metal-to-metal contact to seal the cylinder against blow-by
D . assure a positive means of scraping carbon accumulation from the cylinder
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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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Cold clearances between the skirt of an aluminum piston and the cylinder liner is about （）
A . twice as large as with a cast iron piston
B . the same size as with a cast iron piston
C . half as large as with a cast iron piston
D . the same size as the crown of an aluminum pisto
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(Piston area)X(Piston stroke)K(numbers of the cylinders)=engine（）
A . brake horsepower
B . displacement
C . cylinder volume
D . cylinder clearance
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The outside diameter of the pipe is （） the diameter of the bore of the piston rod, the result being that an annular space formed between the piston rod and the pipe.
A . less than
B . greater than
C . equal to
D . twice larger tha
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The scavenging air ports are located at （） that they are just exposed by the upper edge of the piston when the piston is in the bottom dead center position.
A . so a height
B . such a height
C . so high
D . such high
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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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The upper section of a piston is called the （）
A . land
B . skirt
C . crown
D . plate
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Which of the following statements represents the function of the compression rings installed at the top of a diesel Engine piston?（）
A . Control the amount of lube oil burned in the combustion chamber
B . Transmit heat from the piston to the cylinder liner
C . Prevent damage to ring groove inserts by acting as a heat dam
D . Dissipate combustion chamber gas pressure by channeling it through the ring ga
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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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The position of the piston parts in relation to each other is secured by means of （） and a dowel pin in the crown.
A . bosses
B . through bolts
C . machine-turned recesses
D . long stud
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The lower end of each piston rod is reduced in diameter to fit a bore in the cross-head, this being secured to the piston rod by （）.
A . a bolt
B . a cap
C . a disc
D . a nut
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During working, when the piston is near the （）, the air ignites the fine spray of fuel.
A . TDC
B . DTC
C . BDC
D . BCD
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Among the rings of a piston the （） one is subjected to the greatest load and temperature.
A . bottom
B . middle
C . top
D . none of the above
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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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The perception of color is a function of the （0.5分）
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On engines having oil cooled pistons the lubricating oil pre-heater must be put into operation and the rate of heating so ______ that the temperature of the piston cooling oil returns are 32 to 35℃ over a period of at least two hours.
A.slow
B.quick
C.arranged
D.high
