-
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
-
The purpose of the wearing rings used in a centrifugal pump is to （）.
A . prevent an internal explosion in the pump when it is overheated
B . enable a visual inspection of the pump while it is running
C . insure a proper alignment of the pump coupling to the driver
D . accommodate for friction between the impeller and the easing
-
A diesel engine piston ring face is in direct contact with the （）.
A . top of the ring groove
B . cylinder liner oil film
C . bottom of the ring groove
D . back of the ring groove
-
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
-
The piston ring grooves for a standard engine are （）
A . chromium-plate against wear
B . anti-corrosion treated
C . white metal lined against wear
D . flame hardened against wear
-
Each piston stuffing box is provided with two sealing rings and three（）
A . packings
B . piston rings
C . distributor rings
D . scraper ring
-
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
-
In a diesel engine, when installing new piston rings it is important to check（） Ⅰ.ring gap clearance Ⅱ.side clearance
A . Ⅰ only
B . Ⅱ only
C . both Ⅰ and Ⅱ
D . neither Ⅰnor Ⅱ
-
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
-
These piston rings are so badly worn that they must be （）.
A . renewed
B . welded
C . machined
D . chromium-plated
-
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
-
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
-
Improperly fitted piston rings in a diesel engine can cause（）
A . excessive lube oil consumption
B . lower than normal lube oil temperature
C . higher than normal exhaust back pressure
D . excessive crankshaft end play
-
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
-
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
-
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
-
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
-
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
-
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
-
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
-
Diesel engine piston ring blow-by is usually caused by excessive ring clearance at the ring（）
A . back
B . side
C . gap
D . bottom
-
If clearance between a piston and the cylinder wall is excessive, piston slap will occurThe slap itself is caused by （）
A . alternation of side thrust
B . a breakdown of the lube oil film on the cylinder wall
C . worn piston boss piston pin bearings
D . fluctuating gas pressure in the combustion space
-
The lowest ring of a piston is （）.
A . a coil spring
B . a sealing ring
C . an oil distributor ring
D . main seal ring
-
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
