This set of Machine Design Multiple Choice Questions & Answers (MCQs) focuses on “Worm Gears”.
1. Worm gear drives are used to transmit power between two non-intersecting shafts which are generally at right angles to each other.
Explanation: This is how the worm gear design fits into use.
2. The worm and worm wheel both are threaded screw.
b) Worm wheel is a toothed gear
c) Worm is a toothed gear
d) None of the listed
Explanation: Worm wheel is a toothed gear.
3. Which of the following is not true about worm gears?
b) Smooth and silent operation
c) Low speed reduction
d) All the mentioned are true
Explanation: Speed reduction can be high up to 100:1.
4. Is it possible to use worm gears in cranes for lifting purpose?
b) No self-locking and hence not possible
c) Possible up to a threshold load
d) None of the listed
Explanation: Worm gears support self-locking operation and hence are advantageous to use in lifting operations.
5. The power transmitting capacity of worm gears is high although efficiency is low.
Explanation: Both power transmitting capacity and efficiency of worm gears are low.
6. Can worm gears be used in steering mechanism?
Explanation: In steering mechanism, efficiency is of little importance but major requirement is of large mechanical advantage.
7. The worm helix angle is the _____ of the worm lead angle.
Explanation: Worm helix angle+worm lead angle=90⁰.
8. If worm helix angle is 30⁰, then worm should have at least ___ threads.
Explanation: The permissible helix angle is 6⁰ and hence there should be at least five threads i.e. 30/6.
9. A pair of worm gear is written as 2/40/12/6. Calculate the centre distance.
Explanation: C=m(q+z)/2 where m=6mm, q=12 and z=40.
10. A pair of worm gear is written as 2/40/12/6. Calculate the speed reduction.
11. A pair of worm gear is written as 2/40/12/6. Calculate the pitch circle diameter of worm wheel.
Explanation: d=mxz where m=6mm and z=40.
12. A pair of worm gear is written as 2/40/12/6. Calculate the throat diameter of the worm wheel.
Explanation: d(t)=m[z+4cosϒ-2] where ϒ=9.46⁰ is the lead angle. tanϒ=2/12, z=40 and m=6mm.
13. A pair of worm gear is written as 2/40/12/6. Calculate the root diameter of the worm wheel.
Explanation: d=m[z-2-0.4cosϒ] where ϒ=9.46⁰ is the lead angle. tanϒ=2/12, z=40 and m=6mm.
14. If tangential force on worm is 1500N, then axial force on worm wheel will be?
c) 1500√2 N
Sanfoundry Global Education & Learning Series – Machine Design.
To practice all areas of Machine Design, here is complete set of 1000+ Multiple Choice Questions and Answers.