AUTOMATIC TRANSMISSION Presented By, Guided By, Muhammed RiyasGopinathan.V Muhammed RiyasGopinathan.V S 7 M B Asst:Prof S 7 M B Asst:Prof NO:103Dept of Mechanical Engg NO:103Dept of Mechanical Engg

Introduction Device which changes gear ratios automatically Device which changes gear ratios automatically Deliver maximum efficiency Deliver maximum efficiency Difference between automatic and manual transmission Difference between automatic and manual transmission Easier to drive because they do not have a clutch pedal or gearshift lever Easier to drive because they do not have a clutch pedal or gearshift lever There are two type of automatic transmissions There are two type of automatic transmissions

CLASSIFICATION AUTOMATIC TRANSMISSIONS USING PLANETARY GEARS AUTOMATIC TRANSMISSIONS USING PLANETARY GEARS CONTINUOUSLY VARIABLE TRANSMISSION(CVT) CONTINUOUSLY VARIABLE TRANSMISSION(CVT)

AUTOMATIC TRANSMISSIONS USING PLANETARY GEARS Components PLANETARY GEAR SYSTEM PLANETARY GEAR SYSTEM TORQUE CONVERTER TORQUE CONVERTER HYDRAULIC SYSTEM HYDRAULIC SYSTEM GOVERNOR GOVERNOR COMPUTER CONTROLS COMPUTER CONTROLS

1.Sun gear 2. Planet gear 3. Ring gear 4. Planetary carrier PLANETARY GEAR SYSTEM

PLANETARY GEAR SYSTEM (SIDE VIEW)

HOW PLANETARY GEARS WORK InputOutputStationaryCalculationGear Ratio ASun (S)Planet Carrier (C)Ring (R)1 + R/S3.4:1 BPlanet Carrier (C)Ring (R)Sun (S)1 / (1 + S/R)0.71:1 CSun (S)Ring (R)Planet Carrier (C)-R/S-2.4:1 GearInputOutputFixedGear Ratio 1st30-tooth sun72-tooth ringPlanet carrier2.4:1 2nd 30-tooth sunPlanet carrier36-tooth sun2.2:1 Planet carrier72-tooth ring36-tooth sun0.67:1 Total 2nd1.47:1 3rd 30- and 36-tooth suns 72-tooth ring1.0:1 ODPlanet carrier72-tooth ring36-tooth sun0.67:1 Reverse36-tooth sun72-tooth ringPlanet 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.

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.

TORQUE CONVERTOR

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

Gear pump Oil Pump Gear pump 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.

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.

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.

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

GOVERNER provides the inputs that tell the transmission when to shift provides the inputs that tell the transmission when to shift connected to the output shaft and regulates hydraulic pressure based on vehicle speed connected to the output shaft and regulates hydraulic pressure based on vehicle speed

COMPUTER CONTROLLS Detect such things as throttle position, vehicle speed, engine speed, engine load,etc. to control exact shift points 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. 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. 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. Inhibit the Up shift when going into a turn on a winding road.

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

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