This document discusses different types of automatic transmissions. It describes automatic transmissions using planetary gears, which use a planetary gear set, torque converter, hydraulic system and computer controls to automatically shift gears. It also describes continuously variable transmissions, which can change through an infinite number of gear ratios without discrete shifts. The document provides details on how planetary gears and torque converters work within automatic transmission systems. It notes future automatic transmissions may integrate more touch screen controls.

1. BY:
A Sujendra Kumar

2. CONTENTS
 Introduction
 Classification
 Automatic transmission using planetary gears
 Continuously variable transmission
 Future scope
 Conclusion
 References

3. INTRODUCTION
 Device which changes gear ratios automatically
 Gives maximum efficiency as output
 Easier to drive because they do not have a clutch pedal
or gearshift lever
 Automatic transmissions contain mechanical systems,
hydraulic systems, electrical systems and computer
controls, all working together in perfect harmony.

4. CLASSIFICATION
 Automatic transmissions using planetary gears

5.  Continuously variable transmission(cvt)

6. AUTOMATIC TRANSMISSIONS
USING PLANETARY GEARS
Components :
• Planetary Gear System
• Torque Converter
• Hydraulic System
• Governor
• Computer Controls

7. HOW PLANETARY GEARS WORK
 A gear set in which all of the gears are grouped around
each other like the planets around the sun.
 The central gear is called sun gear. In mesh with it is a
circular grouping of gears, called planet gears,
mounted on a rotating carrier.
 By holding any one of the three gear elements
motionless, different ratios can be produced between
the other two. Planetary gear sets are common in
automatic transmissions.

9. TORQUE CONVERTOR
 Takes the place of the clutch found on standard shift
vehicles
 It uses oil or transmission fluid to transmit power
 Torque converter can be divided into 3 main
members:
a. Pump/impeller: It is the driving member and rotates
with the engine.
b. Turbine: The impeller vanes pick up fluid in the
converter housing and direct it toward the turbine.
c. Stator: Fluid flow drives the turbine, and the turbine
rotates and turns the transmission input shaft.

10. TORQUE CONVERTOR

11. VALVE BODY
 The brain of the automatic
transmission
 Contains a maze of channels and
passages that direct hydraulic
fluid to the numerous valves
 These valves activate the
appropriate clutch pack or band
servo to smoothly shift to the
appropriate gear for each driving
situation.

12. Shift Valves
 Supply hydraulic pressure to
the clutches and bands to
engage each gear
 Determines when to shift from
one gear to the next
 The 1 to 2 shift valves
determines when to shift from
first to second gear.

13. Continuously variable transmission
 A continuosly variable transmission
is a transmission which can change
steplessly through an infinite
number of effective gear ratios
between maximum and minimum
values.
 CVTs operate smoothly since there
are no gear changes which cause
sudden jerks .
 There are 25% fewer moving parts
to a CVT transmission

14. Future scope
 As to present era the evolution in auto mobiles is also
changing according to the modern culture.
 In future the touch screens will be implemented to the
vehicles.
 To control the speed and transmission.

15. CONCLUSION
 Automatic transmissions contain mechanical systems,
hydraulic systems, electrical systems and computer
controls, all working together in perfect harmony