250+ TOP MCQs on Lubrication and Lubricants – Oil Pumps and Answers

Automotive Engine Auxiliary Systems Multiple Choice Questions on “Lubrication and Lubricants – Oil Pumps”.

1. Which among the following helps in the increase in the oil pressure in an engine?
a) Engine speed
b) Coolant flow
c) Clearance
d) Engine temperature
Answer: a
Clarification: The Oil Pressure in the engine increases with the increase in engine speed which would increase the working speed of the oil pump.

2. What is the direction of rotation of a driven gear in a gear pump if the driving gear rotates in an anticlockwise direction?
a) Clockwise
b) Anticlockwise
c) Has no effect
d) Rotates on its own
Answer: a
Clarification: Both the gears are meshed due to which the driving gear rotates anticlockwise and the driven gear rotates in the clockwise direction in a gear-driven gear pump.

3. How are the axes of rotation of two rotors present in a rotor pump?
a) Same
b) Different
c) Do not depend on each other
d) Has no effect
Answer: b
Clarification: The axes of rotation of the two rotors are different which causes the size of the spaces between them to vary.One of the rotors gets its drive from an engine which causes the other rotor to rotate along with it.

4. Which is the force acting on the vanes due to which the vanes are pressed outwards against the housing?
a) Centrifugal
b) Tension
c) Frictional
d) Air resistance
Answer: a
Clarification: When the vane pump operates, the vanes are pressed outwards against the housing by the centrifugal force. The oil enters the inlet port and is swept by the vanes to the outlet port.

5. How do the outer and inner gear mesh in a Crescent type gear pump?
a) Externally
b) Internally
c) Both a and b
d) Do not mesh with each other
Answer: b
Clarification: Crescent type gear pump the outer Gear and the inner gear is in mesh internally due to this space which is of a crescent shape hence the name.

6. How is the number of lobes on the outer rotor when compared to the inner rotor lobes in a rotor pump?
a) Less
b) More
c) Same
d) Has no effect
Answer: a
Clarification: In the rotor pump the outer rotor always has 1 less lobe when compared to the inner rotor wherein the extra space the oil gets compressed.

7. The plunger pump is an example of which type of pump?
a) Rotary
b) Reciprocating
c) Radial
d) Centrifugal
Answer: b
Clarification: Plunger pump is a reciprocating type of pump in which the oil gets communicated from the inlet to the outlet by alternate suction and pressure created by a reciprocating plunger.

8. How is the oil flow in a vane-type pump?
a) Continuous
b) Dis-continuous
c) Turbulent
d) Laminar
Answer: a
Clarification: The vane-type pump there is an advantage of a continuous oil flow compared to the pulsating oil flow in case of the gear pump.

9. What is the range of pressure oil with which the gear pump delivers?
a) 0-100KPa
b) 100-200KPa
c) 200-300KPa
d) 300-400KPa
Answer: d
Clarification: The gear pump is always submerged in oil and the pump delivers oil at about 300-400KPa. Hence 300-400KPa is the range of oil pressure.

10. How should be the bearing clearance for higher oil Pressure?
a) More
b) Less
c) Zero
d) Does not affect oil pressure
Answer: b
Clarification: The lesser clearance would mean higher oil pressure delivered at the outlet.Any restriction in the lubrication passages would also increase the oil pressure.

11. What is the use of the Spring ball valve in a gear pump?
a) To know the temperature
b) To cutoff the rotation of the gears
c) To know the pressure level
d) None of the above
Answer: c
Clarification: When the pressure exceeds the prescribed value, the spring is compressed and the ball is lifted off its seat and the oil passes back to the inlet side through the bypass provided.

12. How much more is the efficiency of the Rotor pump when compared to the gear type?
a) 5%
b) 10%
c) 20%
d) 25%
Answer: d
Clarification: The Rotor type pump is about 25% more efficient and compact than the gear type pump. So, they are used very widely in automobiles.

13. What is the name of the space that is formed between two gears due to eccentricity?
a) Crescent
b) Triangle
c) Rectangle
d) Circle
Answer: a
Clarification: Due to eccentricity, there is a space in between two gears where the crescent space is placed. The crescent shape both offsets the idler gear and provides a seal between the suction and discharge ports.