The document discusses automatic transmissions for automobiles. It begins by introducing automatic transmissions and their main components. There are two main types: ones using planetary gears and continuously variable transmissions. It focuses on transmissions using planetary gears. These systems use a planetary gear set, torque converter, hydraulic system, governor and computer controls to automatically shift gears based on driving conditions. The hydraulic system sends fluid through the transmission to control shifting, while the governor and computer monitor vehicle speed and other factors to determine appropriate shift points.

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