1. What is meant by a belt drive?
When power is driven from driver pulley to driven pulley by means of belt , it is known as belt drive. In open belt drive both the pulleys run in the same direction and in cross belt drive both the pulleys run in opposite direction to each other.
- The belt is loosely fitted.
- Overloading on belt drive.
- Misalignment of pulleys.
- Load of the machine.
- Speed of the machine.
- Capacity of machine.
- Atmosphere of the climate.
Jockey pulley is used to increase the contacting area in between the belt and pulley and also used to press the belt for giving tension.
6. Define Crowning in belt drive?
The outer surface or face of rim of the pulley is made in convex form to keep the belt in center when it is in movement, it is called crowning.
7. What is dressing in belt drive?
To avoid slip or creep, the resin powder or paste is poured in between the outer surface of pulley and belt for increasing the tension is called dressing.
8. Write short notes on creep and slip in belt drive?
- The movement of belt upon the face of rim or outer surface of driver and driven pulleys within the area of arc of contact is called creep in belt drive.
- If the belt is loosely fitted on pulleys, it slips down which is called slip in belt drive.
9. What are the rules for belt drives?
- The distance between two pulleys should not be less than three times the diameter of the larger pulley.
- The slack side should be uppermost which may increase the arc of contact.
- The ratio of diameter of both the pulleys should not exceed 6:1.
- If necessary ,a jockey pulley should be used to minimize the slip.
10.What are the advantages and disadvantages of V belt?
- The main advantages of V belt are it has more gripping power, long life and it occupies less space.
- Disadvantages are it is not fit for long distances and cross belt drive.
11. What are the functions of gears?
- To change the direction of rotation
- To change the speed.
- To change the plane directions.
- To transmit power.
- To give positive drive.
12. What do you mean a worm drive?
Worm drive consists of a worm and worm wheel and the worm wheel is always driven by the worm. It is suitable for heavy loads and also for speed reduction.
13. What is spur gear?
It is a common type of gear having teeth in straight. It is used to transmit the motion on parallel shafts and used for all general purpose for transmitting motion.
14. What is the difference between Addendum and Dedendum?
- Addendum is the distance from the top of tooth to the pitch circle.
- Dedendum is the distance from the root to the pitch circle of gear tooth.
15. Define Chordal thickness?
It is distance in straight line from tooth to tooth along the pitch circle.
16. What is Module?
It is the ratio between the pitch diameter and the number of teeth in the gear.
17. Define Diameteral pitch?
Diameteral pitch is the ratio between the number of teeth of a gear and the pitch circle diameter.
18. Which gears are used to connect the shafts lying in the same plane?
Spur gears, Helical gears, Internal gears and Herringbone gears
19. Differentiate between Herringbone gears and Helical gears?
- Herringbone Gears . Double helical gears are known as Herringbone gears. These gears have teeth in series on both sides from the centre in the inclined position to the axis. These type of gears are used to transmit motion at high speed with heavy load without producing noise.
- Helical Gears. These type of gears have teeth in series of single way in an inclined position. Helical gears are used to transmit the motion at high speed without producing noise.
20. Which gears are used to connect the shafts which intersect at same angle?
Bevel gears and angle gears.