# Machine Design Questions and Answers – Gears

This set of Machine Design Multiple Choice Questions & Answers (MCQs) focuses on “Gears Introduction”

1. The common normal to the curves of the two teeth must not pass through the pitch point.
a) True
b) It must pass
c) It may or may not pass
d) None of the listed

Explanation: The common normal must pass through the point where two mating gears meet.

2. Which of the following can be used for power transmission in intersecting shafts.
a) Spur Gear
b) Helical Gear
c) Bevel Gear
d) None of the listed

Explanation: Bevel gears are used for power transmission in case of intersecting shafts.

3. Is it possible to transmit power between shafts lying in different planes using gears?
a) Yes
b) No

Explanation: Worm or crossed helical gears can be used in this case for power transmission.

4. The two gears are said to have conjugate motion if
a) They have constant angular velocity ratio
b) Variable angular velocity ratio
c) Infinitely small angular velocity ratio
d) None of the mentioned

Explanation: Two gear are said to have conjugate motion and tooth profiles are said to have conjugate curves if they have constant angular velocity ratio.

5. Which of the following is not true about gears?
a) Positive drive
b) Constant velocity ratio
c) Transmit large power
d) Bulky construction

Explanation: They have compact construction.
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6. Gear drive don’t require precise alignment of shafts.
a) True
b) False

Explanation: A minute level of misalignment isn’t tolerated in gears.

7. Spur gears can be used only when the two shafts are parallel.
a) True
b) False

Explanation: The teeth are cut parallel to the axis of shaft.

8. The teeth of the helical gears are cut parallel to the shaft axis.
a) True
b) False

Explanation: They are cut at an angle with the shaft axis.

9. Herringbone gear can be used in
a) Intersecting shafts only
b) Parallel shafts only
c) Both intersection and parallel shafts
d) None of the mentioned

Explanation: It consist of two helical gears with the opposite hand of the helix.

10. Bevel gears impose ____ loads on the shafts.
c) Thrust

Explanation: Bevel gears have the shape of a truncated cone and tooth is cut straight or spiral.

11. Which of the following are true for worm gears?
a) Worm is in the shape of threaded screw
c) Worm imposes high thrust loads
d) Characterised by low speed reduction ratio

Explanation: They are characterised by high speed reduction ratio.

12. Greater the velocity ratio, smaller the gearbox.
a) True
b) Greater the gearbox
c) Size of gearbox remains unaffected
d) None of the listed

Explanation: Greater velocity leads to increase in size of gear wheel which results in size of gearbox.

13. Required velocity ratio is 60:1, which of the following are recommended?
a) Worm
b) Spur
c) Bevel
d) None of the mentioned

Explanation: For high speed reduction ratio, worm gears are recommended.

14. For a constant velocity ratio, the common normal to the tooth profile at point of contact must pass through a continuously variable point.
a) True
b) It pass through a fixed point
c) Constant velocity ratio isn’t required, hence variable point is preferred
d) None of the listed

Explanation: It must pass through a fixed point called pitch to maintain a constant velocity ratio.

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