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Power transmission Drives | Machine Design – Interview Question and Answers

Power Transmission Drives Question and Answers :

1. What is a power drive? Mention their types.
The power drive is a set of machine members employed to transmit power or energy produced in one machine to another machine.
Their main types
(1) Mechanical,
(2) Hydraulic,
(3) Pneumatic and
(4)Electrical drives.

2. What is meant by mechanical drives? Classify them.
The drives which transmit power by means of contact forces are called as mechanical drives. They can be classified based on
(a) Way of power transmission.
(i) Friction drives [E.g. Belt drives, Rope drives]
(ii) Toothed drives [Eg.. Gear drives, Chain drives]
(b) Centre distance between power shafts
(i) Long distance drives (Eg. Belt drives, chain drives, rope drives)
(ii)Short distance drives (Eg. Gear drives)
(c) Intermediate link between driving and driven members.
(i) No intermediate link (Eg. Gear drives)
(ii) With intermediate link (Eg. Belt, rope drives, chain drives)

Belt and Pulley – Interview Question and answers

3.State the -Law of Belting’
The law of belting states that the centerline of the belt when it approaches the pulley must lie in the midplane of that pulley which should be perpendicular to the axis of the pulley. Otherwise the belt will runoff the pulley.

4.Explain the term crowning of pulleys.
Pulleys are provided. a -slight conical shapes (or),.,,convex shapes in their rim’s r surface in order to prevent the belt from running off the pulley due centrifugal force. This is known as crowning, of pulley. Usually the crowning height t may be 1/96 of pulley face width.

5.Briefiy explain about friction and its applications
Friction is said to be a resisting force that is developed between two relatively -moving surfaces. For some machines, this frictional force may be, an unwanted force and hence it is to be reduced to the maximum level. For some other machines. Bearings brakes, clutches are the good examples.

6.What are the types of belts?
(a) Flat Belts
(b) V Belts
(ii) multiple V belt
(iii) Ribbed Belt.
(c) Toothed or Timing
(d), Round, Belts.

7. State the materials for belts.
Leather,, cotton fabrics ,rubber, animal’s hair, silk, rayon, woolen etc

8. Indicate some merits and demerits of belt-drive;

Merits
1. Belt drives are used for long distance power transmission.
2, Their operations are smooth and flexible.
3. Simple in design and their manufacturing cost is lower.
Demerits,.
1. They need large space.
2. Loss of power due to friction is more.

9. By what materials, belt-pulleys are made?
Belt-pulleys are made of cast-iron or steel

10. What is meant by the ply of belt?
Flat belts are.made of thin strips and laminated one over the other in order to get thick belt. These thin strips or sheets are called as plies of belt. Usually flat belts are made of 11 ply, 4 ply, 5 ply, 6 ply and 8 ply belt etc And 4 ply belt is thicker han 3 ply belt and so-on.

11. Mention the different types of joints employed for joining flat-belts.

(i) Cemented joints

(ii) Laced joints

(iii) Crest joints.

(iv) Hinged joints.

12.What conditions should be followed when flat belt drive is installed?
1. The axes of power transmitting shafts should be parallel.
2. It should have, optimum center distance between the shafts’.
3. The tight-side of the drive should be at the bottom side of the pulley.

13.What is belt rating?
Flat-belts are made of different sizes such as 3 ply, 4 ply and V – belts are made of different grades such as A, B, C, D and E grade belts. Belt rating is defined as the power transmitting capacity of unit size flat belt or a particular grade single V belt.

14. Specify the application of round belt.
Round-belt is applied, in sewing.machine.

15.Specify the purpose of crowning of bets.
To prevent slipping from pulley due to centrifugal force

16.What factors should be considered during the selection of a belt drive?
a) Amount of power to be transmitted.,

b) Peripheral and angular speeds.

c) Speed ratio.
d) Efficiency.

e) Centre distance between staffs

f) Space available.

g) Working environment.

17. Explain creep in belts.
Since the tensions produced by the belt on the two sides of the pulley are not equal, the belt moves with a very negligible velocity, due to the difference of two tensions. This slow movement of the belt over the pulley is known as creep of belt and it is generally neglected.”

18. How is a V-belt designated?
V-belt is designated by a grade letter followed by its inside length in code number, year of coding. For example, D 3048: IS 2494: 1964. M belts are designated by the grade letter and inside length only such D – 3048. Sometimes, the inside length may be denoted
in inches as D

19. In what ways, timing belts are superior to ordinary V-belts?

Since the timing belts possess toothed shape in their -inner side, engagement with toothed pulley will provide positive drive without, belt-slip where as in the case of ordinary Vbelts, chances of slip are and hence positive drive is not possible at all times. Hence toothed belts (I timing belts) are superior to ordinary V-belts.

Chain and Sprocket- Interview Question and Answers :

20. Write the features of a chain drive.
A chain drive is a flexible mechanical drive which may be considered to be intermediate between belt drive and gear drive in that it has features common to both, Chains are suitable for long as well as short center distance drives and give a more compact, drive than is possible with belts. Chain drives are similar to belt drives in which the chains, are operated between toothed wheels called as sprockets.

21. Mention the applications of chain drives.
Chain drives are employed in transportation machineries like motor-cycle, bi-cycles, automobiles and technological machineries, like agricultural machines, crushes etc.

22. What are the advantages of chain drives?
Chain drives
1. Are having more power transmitting capacity.
2. Have higher efficiency and compact size.
3-Exert -less load on shafts since no initial tension is applied on the sprocket shafts.
4. Require easy maintenance

23. Specify some drawbacks of chain drives.
1. The design of chain drive is more complicated.
2. The operation is noisy and production cost is high.
3. They require more accurate assembly bf shafts than for belts.

24. Indicate the types of chains.
a) Driving chains b) Hauling chains c) Loading chains.