Gear trains – Speed ratio, train value – Parallel axis gear trains – Epicyclic Gear Trains.

1. GEAR TRAIN
UN IT-4

2. INTRODUCTION
GEAR TRAIN
It’s a combination of wheels by means of
which motion is transmitted from one shaft to
another shaft

3. .
Application

4. Introduction
Velocity Ratio AND Train Value Of Gear Train
TRAIN VALUE
Positive value of train value indicates both driver and driven
rotates in same direction
Negative value of train value indicates driver and driven
rotates in opposite direction

5. GEAR TRAINS
Simple Gear
Train
Ordinary Gear
Train
Epicyclic Gear
Train
.
Compound
Gear Train
.
Simple
Epicyclic Gear
Train
Non-Reverted Gear
Train
Reverted
Gear Train
Compound
Epicyclic Gear
Train

6. SIMPLE GEAR TRAIN
.
When there is only one gear on each shaft.
Gear 1 is called Driver
Gear 2 is called Driven or Follower
NI TI = N2T2

7. PROBLEM
Two parallel shafts are connected by a simple gear train. The speed of the driving gear
and the driven gear is 360 rpm and 120 rpm respectively. The number of teeth on the
driving gear is 30. Determine i) Speed ratio ii) The Train Value iii) Number of teeth on
the driven or Follower

8. IDLE or INTERMEDIATE GEAR TRAIN
.

9. .
.
IDLE or INTERMEDIATE GEAR TRAIN
Its clear that from above ‘ intermediate gears do not affect the velocity Ratio’
NI TI = N2T2
N2 T2 = N3T3
N3 T3 = N4T4

10. Compound Gear Train
.

12. .

13. COMPOUND GEAR TRAIN
.
ADVANTAGES
1. Larger speed ratio can be obtained
with smaller gears
2. Different gears can be used in order to
suit the given conditions.
3. Motion can be transmitted in the
round bends and corners

14. .
COMPOUND
GEAR TRAIN

15. .
PROBLEM

16. .
PROBLEM

17. .
PROBLEM

18. .
PROBLEM

22. REVERTED GEAR TRAIN
.

23. The centre distance between the shaft of gears 1 and 2 and 3 and
4 are the same
REVERTED GEAR TRAIN

24. .
.

25. EPICYCLIC GEAR TRAIN
A gear train that consists of one or more outer
gears rotating around a central gear. Epicylic
gear trains are also known as planetary gear
trains.

26. APPLICATIONS

27. TYPES
TYPES
1. SIMPLE EPICYCLIC GEAR TRAIN
2. COMPOUND EPICYCLIC GEAR TRAIN

28. SIMPLE EPICYCLIC GEAR TRAIN
When only one gear on each shaft in any
epicyclic gear train is called simple epicyclic
gear train

29. COMPOUND EPICYCLIC GEAR TRAIN
When there are more than one gear on a shaft in
any epicyclic gear train is called as compound
epicyclic gear train

30. METHODS TO FIND VELOCITY RATIO
1. Tabulation Method
2. Algebraic or Formula Method