单选题As the plunger moves upwards in the barrel, injection will commence once the plunger has （） the spill ports and the pressure builds up.Aopened upBclosed offClined upDtaken off
单选题
As the plunger moves upwards in the barrel, injection will commence once the plunger has （） the spill ports and the pressure builds up.
A
opened up
B
closed off
C
lined up
D
taken off
参考解析
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相关考题：
The plunger in a jerk pump is rotated until the release port is uncovered If the port remains uncovered all of the time, which of the listed operations will occur?A.No fuel will be deliveredB.The maximum effective stroke will be attainedC.The fuel delivered to the cylinder will be excessiveD.The injection nozzle will overheat and carbonize
As the plunger moves upwards in the barrel, injection will commence once the plunger bas_______the spill ports and the pressure builds up.A.opened upB.closed offC.lined upD.taken off
An increase in the fuel injection pump discharge pressure can be caused by a/an _______.A.leaking delivery valveB.excessive bearing end playC.plugged injector spray holeD.increased plunger stroke
材料：A typical example of a hydraulic governor is the Woodward. This has adjustable droop for parallel operation and it is fitted with a speed-adjusting control . If required it can be fitted with a synchronizing motor to provide remote control from a switchboard.A gear pump driven from the engine supplies oil under pressure to accumulator pistons under which is a by-pass to regulate maximum pressure. One branch supplies oil which acts on top of the power piston, the pressure always tending to turn the terminal shaft to shut off fuel, while the other branch supplies oil to the pilot valve which is operated by the linkage from the fly weights above.Should the speed of the engine decrease due to increased load the flyweights will move towards their center of rotation and lower the position of the pilot valve plunger, admitting oil pressure from the bottom of the power piston. Since, however, the area on the bottom is much greater than the top the net resultant force causes the piston to move upwards. This operates the power lever turning the terminal shaft which varies the cut-off point in the fuel pump through linkage, but as the power piston moves up, the actuating compensating piston moves down.Oil under this piston is now forced through the needle valve to the receiving compensating piston, raising the outer end of the floating lever and the pilot valve plunger until it has returned to its normal position. This stops further movement of the terminal shaft so that the fuel control is now set in a position corresponding to the increased fuel required to run the engine at normal speed under the increased load.问题：This passage is mainly about ___.A.what type of governor should be provided when the engine is used for electric power generationB.why the speed of the engine fluctuatesC.how the governor worksD.how the fuel pumps workThe oil from the gear pump will ___. ① be supplied to the accumulator ② act on the power piston ③ be supplied to the pilot valveA.①B.①②C.②③D.①②③Which of the following is true about the Woodward discussed?A.It is a kind of mechanical governor.B.It can not be used for parallel operation.C.It has speed droop.D.It may only be manually controlled from a switch boarE.When the speed of the engine decreases due to increased load, which of the following will NOT happen?A.The flyweights move towards their centerB.The pilot valve plunger moves towards its normal positionC.The power piston moves downwards until it returns to its normal positionD.The terminal shaft moves to a new position请帮忙给出每个问题的正确答案和分析，谢谢！
The amount of fuel delivered by a helical plunger fuel injection pump is controlled by ______.A.varying the pump discharge pressureB.varying the pump return pressureC.rotation of the pump plungerD.rotation of the pump barrel
单选题In a jerk pump, the amount of fuel that will be forced through the spray nozzle on each upward stroke of the plunger depends on （）Athe pump supply pressureBthe slope of the fuel camChow the plunger is rotatedDthe number of sleeve segments engaged with the rack
单选题As the plunger moves up, the ports are closed and the fuel （） and delivered to the injector nozzle at very high pressure.Abeing compressedBto be pumped upCis pressurizedDare built up
单选题Diesel engine injection lag is caused by（）Acompressibility of the fuelBhigh fuel oil supply flowCscored plunger and barrel packingDexcessive air turbulence
单选题In the common rail system, excessive pressure in the header may be caused by （）Aimproper adjustment of the bypass valveBa dribble in the fuel injection nozzleCinsufficient leak-off through injection nozzle packingDa malfunctioning injection nozzle
单选题The plunger may be rotated in the barrel by a rack and （） on a sleeve which is keyed to the plunger.Apinion arrangementBpush rodChandle barDcam device
单选题In a unit injector the amount of fuel that will be forced through the spray nozzle on each stroke of the plunger depends on （）Athe pump supply pressureBthe slope of the fuel camChow the plunger is rotatedDthe number of sleeve segments engaged with the rack
单选题It is important to note that the injection only takes place when the plunger is moving up the cam （）.Abase circleBslopeCbottom pointDtop point
单选题With Variable Injection Timing the start of injection may be （）as the engine load is reduced.AadvancedBretardedCkept constantDnone of the above
单选题The amount of fuel injection into a diesel engine cylinder by a unit injector, is controlled by（）Athe firing pressure in the cylinderBa metering helix inside the pumpCvarying the physical length of the plunger strokeDvarying the clearance between the injector cam and the injector rocker arm
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单选题Faulty operation of diesel engine fuel injection nozzles can be directly caused by （）.Awater in the fuel oil supplyBexcessive fuel nozzle holder coolingCa distorted fuel spray patternDleakage past the plunger into the oil drain
单选题With reference to an axial piston pump, which one of the following statements is true?（）AThe cylindrical barrel is coupled to the motorBThe cylindrical barrel has an odd number of boresCThe bores end in socketsDThe sockets fit in the swash plate
单选题When disassembling or assembling an injection pump plunger and barrel you should （）Akeep the parts immersed in diesel fuelBalways keep the plunger and barrel togetherCwork over a linoleum-type surfaceDall of the above
单选题An increase in the fuel injection pump discharge pressure can be caused by a/an （）Aleaking delivery valveBexcessive bearing end playCplugged injector spray holeDincreased plunger stroke
单选题Because of the close tolerances used in diesel engine fuel oil pumps, a worn plunger requires（）Agrinding the spare plunger to the barrelBreplacing the plunger and the barrelChighly polishing both the plunger and barrelDreplacing plunger only
单选题If the plunger or barrel of a fuel injection jerk pump becomes damaged,（）Aonly the replacement of the entire pump would be acceptableBthe injection pump and injection nozzle must be replacedCeither the barrel or plunger must be replacedDthe barrel and plunger must be replaced as a unit
单选题The amount of fuel delivered by a helical plunger fuel injection pump is controlled by （）Avarying the pump discharge pressureBvarying the pump return pressureCrotation of the pump plungerDrotation of the pump barrel