1. AUTOMOBILE PRESENTATION
AUTOMATIC
TRANSMISSION
Submitted By:
Ashu Airan (2011ume1495)
Avinash Misra (2011ume1496)
Chetram Meena (2011ume1497)
Deepa Ram Suthar (2011ume1498)

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. PLANETARY GEAR SYSTEM (SIDE VIEW)

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

7. 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.

8. TORQUE CONVERTOR

9. 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

10. 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.

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. BAND
• A band is a steel strap with
friction material bonded to the
inside surface.

14. GOVERNER
• Provides the inputs that tell the
transmission when to shift.
• Connected to the output shaft and
regulates hydraulic pressure based on
vehicle speed.

15. 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.

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