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Mechatronics Multiple Choice Questions on “Hydraulic Pumps”.
1. Which type of mechanical device is used to give energy to the liquid?
a) Fluid power system
b) Hydraulic system
c) Pneumatic system
d) Hydraulic Pumps
Answer: d
Clarification: Pump is a mechanical device which gives energy to the liquid. The liquid can have energy in any of the forms such as Kinetic energy, Pressure energy and potential energy. The fluid Power system is a power transmission system in which, the transmission of power takes place by means of “oil under pressure” or “compressed air”. If “oil under pressure” is used in the system for power transmission then the system is called a hydraulic system. If “compressed air” is used in the system for power transmission then the system is called a pneumatic system.
2. Which among the following pumps have a definite amount of discharge?
a) Positive displacement pumps
b) Non-positive displacement pumps
c) Self-priming pumps
d) Jet pumps
Answer: a
Clarification: In positive displacement pumps, the discharge is positive. The word positive implies that there will be a definite amount of discharge irrespective of an increase in pressure. In non-positive displacement pumps, the discharge is not constant. Self-priming pumps and Jet pumps are the types of non-displacement pumps.
3. The non-positive displacement pumps do not have a constant discharge.
a) True
b) False
Answer: a
Clarification: In non-positive displacement pumps, the discharge is not constant. The discharge reduces with increase in pressure and the discharge becomes zero at maximum pressure. At high pressure, the pump cannot deliver oil. Hence the non-positive displacement pumps have no use in hydraulic systems.
4. Which type of pumps can give discharge even at high pressure?
a) Multistage Pumps
b) Monoblock pumps
c) Rotary pumps
d) Single stage pumps
Answer: c
Clarification: Rotary pumps are positive displacement pumps. Rotary pumps have two or more rotating components. The discharge of rotary components remains almost the same irrespective of pressure. They can give discharge even at high pressure. In the other options, the type of pumps mentioned is all non-positive displacement types.
5. Which type of component in a hydraulic system supports less vibration and noise?
a) Flow control valve
b) Oil reservoir
c) Rotatory pumps
d) Pressure gauge
Answer: c
Clarification: Very less vibration and noise are observed in the case of rotary pumps. These pumps are compact with very a smaller number of moving components. The flow control valves, oil reservoir and pressure gauge are the other parts of the hydraulic system with different functions.
6. The pressure relief valve is an important component which is required for every positive displacement pump.
a) True
b) False
Answer: a
Clarification: Pressure relief valve is an important component which is required for every positive displacement pump. This valve is connected to the outlet of the pump. Its main function is to release the oil back to the tank when the pressure increases beyond pre-set value.
7. Which type of pump consists of two spur or helical gears?
a) External gear pumps
b) Internal gear pumps
c) Rotary pumps
d) Vane pumps
Answer: a
Clarification: The external gear pump consists of two spur or helical gears, which are meshed with each other and mounted inside the casing. One is the driver and another one is driven. The other pumps mentioned in the options does not contain two spur or helical gears.
8. What is the property of a screw pump?
a) Discharge is continuous, smooth and non-pulsating
b) Very less vibration and noise
c) Has two or more rotating components
d) Consists of a left handed and a right handed screw
Answer: d
Clarification: The screw pump is a positive displacement pump which comes with two or three screws. Each shaft has a left hand and a right hand screw, for hydraulic pressure balance. The other properties mentioned in the options are the properties of a rotary pump.
9. What prevents the leakage of oil inside an unbalanced vane pump?
a) Vanes
b) Cylindrical rotor
c) Screw
d) Difference between pressure of inlet and outlet
Answer: a
Clarification: The vanes are seated in the radial slots of the rotor and held against the casing by spring force or hydraulic force. Hence there will not be any leakage of oil between the vane tips and the casing. Still there is a little amount of leakage and hence the volumetric efficiency will be around 95%.
10. Which among the following are not the main selection criteria for selection of hydraulic pumps?
a) Discharge
b) Pressure
c) Speed
d) Weight
Answer: d
Clarification: The weight is not the main selection criteria for selection of hydraulic pumps. There are different values for gear pumps, vane pumps and piston pumps for Pressure, Discharge and Speed which are predefined values.