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 & HODDept. of Mechanical Engg. Dept. of Mechanical Engg. VVCE Mysore VVCE Mysore Department of Mechanical Engineering VidyaVardhaka College of Engineering
INTRODUCTIONThe modern automatic transmission isby far, the most complicatedmechanical component in todaysautomobile. Automatic transmissions containMechanical systems, Hydraulicsystems, Electrical systems andComputer controls, all workingtogether in perfect harmony whichgoes virtually unnoticed until there isa problem.
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.
TYPES OF AUTOMATIC TRANSMISSION Rear wheel drive Front wheel drive
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 70s
REAR WHEEL DRIVE
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.
FRONT WHEEL DRIVE
TRANSMISSION COMPONENTS Planetary Gear Sets Hydraulic System Oil Pump Valve Body Clutches Band Seals and Gaskets Torque Converter Governor Computer Controls
PLANETARY GEAR SETSA gear set in which all of the gearsare in one plane, grouped around eachother like the planets around the sun.The central gear is called the "sungear". In mesh with it is a circulargrouping of gears, called "planetgears", mounted on a rotating carrier.The planet gears also engage teeth onthe inner periphery of the "ring gear".By holding any one of the three gearelements motionless, different ratioscan be produced between the othertwo. Planetary gear sets are common inautomatic transmissions.
CLUTCH PACKSAclutchis a mechanicaldevice which providesfor the transmission ofpower (and thereforeusually motion) from onecomponent (the drivingmember) to another (thedriven member). the simplest application clutches are employed in devices which have two rotating shafts.
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 ofthe clutch housing. It tightens to engage thegears, and loosens to release them.
TORQUE CONVERTERAtorque converterisafluid couplingthatis used to transferrotating power fromaprime mover, suchas aninternal combustion engineor electric motor, toa rotating drivenload.
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
COMPUTER CONTROLSThe computer uses sensors on theengine and transmission to detect suchthings as throttle position, vehiclespeed, engine speed, engine load, brakepedal position, etc. to control exactshift points as well as how soft or firmthe shift should be. Once thecomputer receives this information, itthen sends signals to a solenoid packinside the transmission
NON-COMPUTERIZED TRANSMISSIONS Governor Vacuum Modulator Throttle Cable Seals and Gaskets
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.
TRANSMISSION REPAIRS Adjustments and In-Car Repairs Reseal job Replace accessible parts Complete Overhaul Replacement unit vs. overhaul existing unit
Conclusion Being able to drive a stick-shift means more than just understanding your gears, however. Thats because to shift gears, you usually dont just move the shift lever and be done with it. (You can do this sometimes, but its not recommended in day-to-day driving, and well 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.
References- www.drivetrain.com ZF Sachs AG Ernst-Sachs-Strae 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.htmlwww.fueleconomy.gov/feg/tech_transmission.shtml Google , Wikipedia.