1. AUTOMATIC TRANSMISSION
Presented By, Guided By,
Muhammed Riyas Gopinathan.V
S7MB Asst:Prof
NO: Dept of Mechanical Engg

2. Introduction Device which changes gear ratios automatically
Deliver maximum efficiency
Difference between automatic and manual transmission
Easier to drive because they do not have a clutch pedal or gearshift lever
There are two type of automatic transmissions

3. CLASSIFICATION AUTOMATIC TRANSMISSIONS USING PLANETARY GEARS
CONTINUOUSLY VARIABLE TRANSMISSION(CVT)

4. AUTOMATIC TRANSMISSIONS USING PLANETARY GEARS
Components
PLANETARY GEAR SYSTEM
TORQUE CONVERTER
HYDRAULIC SYSTEM
GOVERNOR
COMPUTER CONTROLS

5. Sun gear 2. Planet gear 3. Ring gear 4. Planetary carrier
PLANETARY GEAR SYSTEM

6. PLANETARY GEAR SYSTEM (SIDE VIEW)

7. HOW PLANETARY GEARS WORK
Power transfer can only take place when one of the members is held at rest or if two of the members are locked.
Input
Output
Stationary
Calculation
Gear Ratio A
Sun (S)
Planet Carrier (C)
Ring (R)
1 + R/S
3.4:1 B
1 / (1 + S/R)
0.71:1 C
-R/S
-2.4:1
Gear
Input
Output
Fixed
Gear Ratio
1st
30-tooth sun
72-tooth ring
Planet carrier
2.4:1
2nd
36-tooth sun
2.2:1
0.67:1
Total 2nd
1.47:1
3rd
30- and 36-tooth suns
1.0:1 OD
Reverse
-2.0:1

8. TORQUE CONVERTOR takes the place of the clutch
found on standard shift vehicles
large doughnut shaped device that is mounted
between the engine and the transmission
it uses oil or transmission fluid to transmit power
three internal elements that work together
to transmit power to the transmission.

9. TORQUE CONVERTOR

10. THE HYDRAULIC SYSTEM
complex maze of passages and tubes that sends transmission fluid under under pressure to all parts of the transmission
and torque converter.
Transmission fluid serves in shift control, general lubrication and transmission cooling.
Keeps the transmission at normal operating temperature
OIL PUMP
VALVE BODY
SHIFT VALVES
BANDS

11. Gear pump Oil Pump Produce all the oil pressure that is
required in the transmission
The oil is then sent, under
pressure to the pressure regulator,
the valve body and the rest of the
components, as required.

12. 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.

13. 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.

14. Band A band is a steel strap with friction material bonded to the
inside surface.

15. GOVERNER provides the inputs that tell the transmission when to shift
connected to the output shaft and regulates hydraulic pressure based on vehicle speed

16. COMPUTER CONTROLLS
Detect such things as throttle position, vehicle speed, engine speed, engine load,etc. to control exact shift points
Downshift automatically when going downhill, to control speed and reduce wear on the brakes.
Up shift when braking on a slippery surface to reduce the braking torque applied by the engine.
Inhibit the Up shift when going into a turn on a winding road.

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

18. THANK YOU