AUTOMATIC TRANSMISSION

1
AUTOMATIC TRANSMISSION

• Presented By,
  Guided By,
• Muhammed Riyas Gopinathan.V
• S7MB AsstProf
• NO103 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 3.41
B Planet Carrier (C) Ring (R) Sun (S) 1 / (1 S/R) 0.711
C Sun (S) Ring (R) Planet Carrier (C) -R/S -2.41
Gear Input Output Fixed Gear Ratio
1st 30-tooth sun 72-tooth ring Planet carrier 2.41
2nd 30-tooth sun Planet carrier 36-tooth sun 2.21
2nd Planet carrier 72-tooth ring 36-tooth sun 0.671
2nd Total 2nd 1.471
3rd 30- and 36-tooth suns 72-tooth ring 1.01
OD Planet carrier 72-tooth ring 36-tooth sun 0.671
Reverse 36-tooth sun 72-tooth ring Planet carrier -2.01
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
pumpOil 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