This document is a seminar report on automatic transmission systems submitted by Vijay Kumar, an 8th semester mechanical engineering student at VVCE Mysore. It discusses the key components of automatic transmissions including planetary gear sets, hydraulic systems, torque converters, clutches, bands and computer controls. It also covers rear-wheel drive and front-wheel drive transmissions, common problems, and repair options. The conclusion emphasizes the importance of keeping transmissions and fluid at the proper operating temperature for long life. References include technical websites and manuals.

1. A seminar Report
On
“Automatic Transmission System”
Submitted by:
VIJAY KUMAR
(4VV07ME054)
VIII Semester
Mechanical Engineering
VVCE, Mysore
On : APRIL 13TH 2011
Under the valuable guidance of :
SRI D V SATISH SRI G B KRISHNAPPA
Asst. Professor Professor & HOD
Dept. of Mechanical Engg. Dept. of Mechanical Engg.
VVCE Mysore VVCE Mysore
Department of Mechanical Engineering
VidyaVardhaka College of Engineering

2. INTRODUCTION
The modern automatic transmission is
by far, the most complicated
mechanical component in today’s
automobile.
Automatic transmissions contain
Mechanical systems, Hydraulic
systems, Electrical systems and
Computer controls, all working
together in perfect harmony which
goes virtually unnoticed until there is
a problem.

3. WHAT IS TRANSMISSION ?
• The transmission is a device that is
connected to the back of the engine
and sends the power from the engine
to the drive wheels
• Purpose of the transmission is to
provide high torque at the time of
starting the engine, hill climbing ,
accelerating and pulling a road.

4. TYPES OF AUTOMATIC
TRANSMISSION
• Rear wheel drive
• Front wheel drive

5. REAR WHEEL DRIVE
• The transmission is usually mounted to the
back of the engine.
• Power flow on this system is simple and
straight forward going from the engine,
through the torque converter, then through
the transmission and drive shaft until it
reaches the final drive where it is split and
sent to the two rear wheels.
• Example of rear wheel – Alpha Romeo
Alfeta in early 70’s

6. REAR WHEEL DRIVE

7. FRONT WHEEL DRIVE
• On a front wheel drive car, the transmission is usually
combined with the final drive to form what is called a
transaxle.
• Transaxle is a device set up in the transmission gear box,
clutch, final drive, combined into a single unit.
. Front-wheel-drive layouts are those in which the front
wheels of the vehicle are driven. The most popular layout
used in cars today is the front-engine, front-wheel drive,
with the engine in front of the front axle, driving the
front wheels.
• This layout is typically chosen for its compact packaging.
• Front axles are connected directly to the transaxle and
provide power to the front wheels.

8. FRONT WHEEL DRIVE

9. TRANSMISSION COMPONENTS
• Planetary Gear Sets
• Hydraulic System
Oil Pump
Valve Body
Clutches
 Band
• Seals and Gaskets
• Torque Converter
• Governor
• Computer Controls

10. PLANETARY GEAR SETS
A gear set in which all of the gears
are in one plane, grouped around each
other like the planets around the sun.
The central gear is called the "sun
gear". In mesh with it is a circular
grouping of gears, called "planet
gears", mounted on a rotating carrier.
The planet gears also engage teeth on
the inner periphery of the "ring gear".
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.

11. SIDE VIEW

12. CLUTCH PACKS
A clutch is a mechanical
device which provides
for the transmission of
power (and therefore
usually motion) from one
component (the driving
member) to another (the
driven member).
the simplest
application clutches
are employed in
devices which have two
rotating shafts.

13. BANDS
A band is a steel strap
with friction material
bonded to the inside
surface.
One end of the band is
anchored against the
transmission case while
the other end is
connected to a servo.
A flexible metal ring fits around the outside of
the clutch housing. It tightens to engage the
gears, and loosens to release them.

15. TORQUE CONVERTER
A torque converter is
a fluid coupling that
is used to transfer
rotating power from
a prime mover, such
as an
internal combustion engine
or electric motor, to
a rotating driven
load.

16. HYDRAULIC SYSTEM
• The Hydraulic system is a complex
maze of passages and tubes that
sends transmission fluid under
pressure to all parts of the
transmission and torque converter
• It works with some components.
 Oil Pump
 Valve Body

17. COMPUTER CONTROLS
The computer uses sensors on the
engine and transmission to detect such
things as throttle position, vehicle
speed, engine speed, engine load, brake
pedal position, etc. to control exact
shift points as well as how soft or firm
the shift should be. Once the
computer receives this information, it
then sends signals to a solenoid pack
inside the transmission

18. NON-COMPUTERIZED
TRANSMISSIONS
• Governor
• Vacuum Modulator
• Throttle Cable
• Seals and Gaskets

19. SPOTTING PROBLEMS BEFORE
THEY GET WORSE
• Watch for leaks or stains under the car.
• Check fluid for color and odor.
• Be sensitive to new noises, vibrations and
shift behavior.

20. TRANSMISSION REPAIRS
• Adjustments and In-Car Repairs
• Reseal job
• Replace accessible parts
• Complete Overhaul
• Replacement unit vs. overhaul existing
unit

21. Conclusion
• Being able to drive a stick-shift means more
than just understanding your gears, however.
That's because to shift gears, you usually
don't just move the shift lever and be done
with it. (You can do this sometimes, but it's
not recommended in day-to-day driving, and
we'll get to it later.) Instead, you have to
press the clutch pedal while you shift. .
Keeping the transmission and its fluid cool,
and in the correct operating-temperature
range is crucial for long life.

22. References-
www.drivetrain.com
ZF Sachs AG
Ernst-Sachs-Straße 62
D-97424 Schweinfurt
Germany
www.zf.com
ZF Sachs Product Information PC A Automated Manual Transmission en ebook
www.sciencedirect.com
www.scribd.co
www.youtube.com
http://www.gears-gearbox.com/semi-automatic-
transmission.html
www.fueleconomy.gov/feg/tech_transmission.shtml
Google , Wikipedia.

23. “THANK YOU”