超星 - Chapter_3_Pumps

单选题

What cause discharge of fluid in an external gear pump?1. the electric motor drives one gear which turns the other gear2. the electric motor drives both the gears simultaneously3. fluid passes between the gears to discharge side4. fluid passes through interior of the casing between teeth and casing and not between the gears

A. 1 and 3
B. 2 and 3
C. 1 and 4
D. 2 and 4

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单选题

The rotation of gears in internal gear pump takes place in ( )

A. same direction
B. different direction
C. none of the above

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单选题

What causes internal leakage in internal gear pump?

A. less tolerance level between the meshing surfaces
B. more tolerance level between the meshing surfaces
C. no tolerance between the meshing surfaces
D. none of the above

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单选题

What is the relation between pressure and overall efficiency for a gear pump?

A. as pressure increases, overall efficiency decreases
B. as pressure increases, overall efficiency increases
C. overall efficiency is not affected by change in pressure
D. none of the above

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单选题

How is the smooth and continuous discharge of fluid achieved in a gear pump?

A. increasing number of teeth
B. decreasing number of teeth
C. none of the above

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单选题

What is the function of the the triangle groove on the valve plate of double acting vane pump? ()

A. The liquid pressure at the bottom and top of the blade is balanced with each other
B. When the sealing volume from the oil absorption area enters into the pressure oil area, the sudden change of pressure is avoided and the flow pulsation is reduced
C. The rotor and blade can rotate freely to keep a certain clearance between them and the port plate
D. When the blade moves radially in the rotor slot, the velocity does not change suddenly, and the impact of vane pump is reduced

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单选题

Which pump can't be used as a bidirectional variable displacement pump ().

A. double acting vane pump
B. single acting vane pump
C. axial piston pump
D. radial piston pump

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单选题

Which force causes vanes to come out of the rotor slots?( )

A. centripetal force
B. centrifugal force
C. friction force
D. none of the above

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单选题

Which of the following statements is true? ( )

A. combination of stator with rotor is known as cartridge unit (泵芯)
B. combination of stator with vanes is known as cartridge unit(泵芯)
C. combination of rotor with vanes is known as cartridge unit(泵芯)
D. none of the above

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单选题

The displacement of hydraulic pump or motor depends on ().

A. fow rate change;
B. pressure change;
C. speed change;
D. structure size.

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