The amount of fluid delivered by a positive displacement pump can be regulated by _____.A.throttling the pressure lineB.changing the speed of the driving rotorC.either A or BD.None of the above is tree
The amount of fluid delivered by a positive displacement pump can be regulated by _____.
A.throttling the pressure line
B.changing the speed of the driving rotor
C.either A or B
D.None of the above is tree
相关考题：
Overheating of the hydraulic fluid in an electro-hydraulic anchor windlass can result from a/an( ).A.overload on the pump motorB.low fluid level in the reservoirC.low fluid viscosity around the shaft sealD.high oil level in the sump
Which statement is NOT true?A.While displacement pump works, volume of the working chamber will increase and decrease alternatelyB.A gear pump always has two gearsC.Any vane pump will have a rotor within a ringD.A balanced vane pump has two outlet ports and they are positioned symmetrically
The pressure of a liquid leaving the pump can be referred to as the ______.A.total headB.discharge headC.net positive suction headD.suction head
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A positive displacement pump is that where the volume of the pump chamber is alternately increased to （） and then decreased to （）.Adraw the liquid in；force the liquid outBforce the liquid out；draw the liquid inCsuction；drawDdeliver；outlet
单选题A screw pump belongs to （） according to its working principle.Areciprocating pumpsBpositive displacement pumpsCcentrifugal pumpsDcentripetal pumps
单选题Gear pumps are of positive displacement type pumps because they discharge a near constant amount of liquid （） pressure.Adepending onBin relative toCregardless ofDbecause of
单选题A variable displacement system of hydraulic drives consists of （）.Aa variable displacement axial piston pumpBa constant displacement axial piston pumpCa reciprocating piston pumpDa centrifugal pump
单选题Which of the following statements about pump operations is NOT a correct statement?（）AIn order for a fluid to be pumped, a fluid must be made to flowBA substance must be cold in order for it to be pumpedCThe kinetic energy imparted by the pump can be used to force a liquid through a hydraulic systemDA pump must receive its energy from an external source
单选题Gear pumps are （） because they discharge a near constant amount of liquid regardless of pressure.Anegative displacement typeBturbine typeCpositive displacement typeDmixed-flow type
单选题Which of the listed pumps is NOT a positive displacement pump?（）ACentrifugalBReciprocatingCGearDRotary
单选题If a hydraulic pump is overheating, the cause may be （）.Aexcessive internal leakage in the pumpBlow discharge pressure and fluid flowCexcessive fluid level in the hydraulic reservoirDoperation of the pump at 100% efficiency
单选题The pump has a constant stroke and the amount of fuel delivered is regulated by rotating （） which has a specially arranged helical groove cut into it.Athe pump cylinderBthe pump camCthe pump plungerDthe pump miler
单选题A positive displacement pump is that where the volume of the pump chamber is alternately （） to draw the liquid in and then （） to force the liquid out.Aincreased；decreasedBdecreased；increasedCdecreased；decreasedDincreased；increased
单选题If a radial piston hydraulic pump fails to deliver rated fluid volume, the cause can be （）.Acontaminated fluidBpitted thrust ringsCworn pintle bearingsDobstructed suctions passage
单选题In a diesel engine, a positive displacement type blower is usually （）Agear drive by the engineBdriven by an exhaust gas turbineCdriven by a camshaftDdriven by separate motor
单选题The amount of fluid delivered by a gear pump can be regulated by （）.Athrottling the pressure lineBchanging the speed of the rotorCeither A or BDNone of the above is true
单选题The quantity of oil injected into the cylinder can be regulated （）.Aby turning the pump plungerBby vary the fuel valve spring forceCby no means by controlling the governorDby enlarging or diminishing the injection hole
单选题The output volume of a positive fixed displacement pump can be changed only by （）.Achanging the angle of the tilting plateBchanging the speed of the pumpCmoving the slide block and rotorDmoving the shaft trunnion block
单选题Which of the following statements is/are true regarding hydraulic pumps in general? （）AVariable volumes can be obtained with gear pumps only by variation of the pump drive speedBA radial piston pump houses sliding pistons in a stationary cylinder block through which passes a rotating pintle or ported shaftCThe amount of fluid displaced per revolution of an axial piston rotary pump is dependent on the angle formed between the cylinder block and valve plateDAll of the above
单选题In a radial piston pump, reversal and control of fluid flow are accomplished by moving the （）.Acentral valveBradial plungerCfloating ringDcylinder body
单选题The pressure of a liquid leaving the pump can be referred to as the （）.Atotal headBdischarge headCnet positive suction headDsuction head
单选题A vane pump belongs to （） according to its working principle.Areciprocating pumpBpositive displacement pumpCcentrifugal pumpDcentripetal pump
单选题The amount of fluid delivered by a positive displacement pump can be regulated by （）.Athrottling the pressure lineBchanging the speed of the driving rotorCeither A or BDNone of the above is tree
单选题Which of the listed conditions can lead to cavitation气穴in a centrifugal pump?（）AVapor pockets formed in the suction flow streamBRough easing volute surfacesCWorn wearing ringsDHeavy fluid in the flow stream
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
单选题The pressure head of a pump is given in the unit of （）.AkgBMPaCmeter fluid columnDNone of the above is true