1. DEPARTMENT:- MECHANICAL ENGINEERING

2. GUIDED BY:- MAYUR MAKWANA PREPARED BY: KHYATI BAROT D1 KAYASTH ABHISHEK D2 SINGAR VIKASH D3 PARMAR DHIRAJ D4 PARMAR AMIT D5

3. CLASSIFICATION OF GEARS A) according to the position of shaft axes. B) according to the peripheral velocity of the gears. C) according to type of meshing of gears.

4. (A) According to the position of shaft axes. Spur gears Helical gears Rack and pinion gears Bevel gears a) Straight bevel gears b) Spiral bevel gears Spiral gears Worm and Worm Wheel

5. (B) according to the peripheral velocity of the gears. Low velocity gears Medium velocity gears High velocity gears

6. (C) according to type of meshing of gears. External gear Internal gear

7. (A) According to the position of shaft axes. Spur gear spur gear used when the axis of two shafts are parallel to each other. These Gears have teeth parallel to to the axis of the shaft. o Straight toothed o Helical toothed Single helical double helical (herringbone)

8. (a) Straight toothed (b)Helical and (c) Double helical gears

9. Helical gears In helical gears the teeth are at some angle called helix angle ,with respect to axis of the shaft. Helical gears run quieter as compared to spur gear since the contact between teeth is gradual.therefore,transmission of load is gradual which results in low impact stresses and reduction in noise. for this reason, the helical used for high speed transmission. The problem of axial thrust in helical gears is eliminated by use of double helical gears called “Herring-bone gears”.

10. Helical gears

11. Rack and pinion gears A rack and pinion is a special case of spur gear in which one gear is having infinite diameter called “Rack”. The rack and pinion is used to transmit the rotary motion into reciprocating motion or vise- versa.

12. Bevel gears when power is required to be transmitted from one shaft to another shaft which are intersecting to each other then Bevel gear are used.genrally,to angle between two shaft is 90`. The bevel gear are of two types: a) straight bevel gears. b) spiral bevel gears.

13. a) straight bevel gears. in straight bevel gears the teeth are formed straight on the cones, and they are parallel to the axis of the gear.

14. b) spiral bevel gears. In spiral bevel gear, the teeth are formed at an angle with respect to its axis. The contact between two meshing teeth is gradual and smooth from start to end, as in case of helical gears.

15. Spiral gear Spiral gears are used to transmit power from one shaft to another shaft which are non parallel and non intersecting. Spiral gears are also called as skew gears or crossed helical gears.

16. Worm and Worm Wheel Worm and Worm Wheel are used to transmit power from the shaft to another shaft which are non intersecting and their axis are normally right angles. Worm and Worm Wheel are used for large speed reduction up to 100:1.

17. (B) according to the peripheral velocity of the gears. Low velocity gears : the gear having peripheral velocity less then 3m/sec. Medium velocity gears: the gears having peripheral velocity between 3to15 m/sec. High velocity gears: the gears having peripheral velocity more then 15 m/sec.

18. (C) according to type of meshing of gears. External gear: In external gear the teeth of gears mesh externally with each other. The larger gear is called wheel and smaller gear is called is pinion.

19. Internal gear In internal gear of gears the teeth of gears mesh internally with each other gear. In internal meshing gear the larger gear is called angular wheel and smaller gear is called pinion.

20. GEAR DRIVE

21. ADVANTAGES &DISADVANTAGES OF GEAR DRIVE Advantages of gear drive 1.Gear drive is positive drive(no slip)i.e. transmit exact velocity ratio from one shaft to another shaft. 2.It can transmit very larger power. 3.It has high transmission efficiency. 4.It requires less space. 5.It is reliable.

22. Disadvantages of gear drive 1.Manufacturing cost of gear is high,since special tools and machinery is required for gear manufacturing. 2. Maintance cost of gear drive is also high due to lubrication requirements. 3.The error in cutting teeth may cause vibrations & noise during operation. 4.It requires precise alignment of shafts.

23. THANK YOU