automotive transmission system

7/28/2019 Automotive Transmission System

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AUTOMOTIVETRANSMISSION SYSTEM


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CONTENTS

Introduction

Process

Types of Transmission System (Rear & Front)

Components of Transmission in Automobiles

1. Hydraulic System

1. Oil Pump

2. Valve Body

3.Clutch Packs

4. Bands

2. Seals and Gaskets

3. Torque Converter4. Governor, Vacuum Modulator, Throttle Cable

5. Computer Controls


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INTRODUCTION

The transmission is a device that is connected to the back of theengine and sends the power from the engine to the drive wheels.

The main aim of an automotive transmission system is to providehigh torque at the time of starting the engine, hill climbing,accelerating and pulling the engine at high loads.

The job of the transmission is to change the speed ratio betweenthe engine and the wheels of an automobile.


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POSITION OF TRANSMISSION


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PROCESS

An automobile engine runs at its best at a certain RPM range and itis the transmission's job to make sure that the power is delivered tothe wheels while keeping the engine within that range.

The transmission uses a range of gears -- from low to high

To make more effective use of the engine's torque as drivingconditions change.

The gears can be engaged manually or automatically.


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TYPES

Rear wheel drive

Front wheel drive


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REAR WHEEL DRIVE

The transmission is usually mounted to the back of the engine.

Power flow on this system is simple and straight forward goingfrom the engine, through the torque converter , then through thetransmission and drive shaft until it reaches the final drive where itis split and sent to the two rear wheels .


9/35REAR WHEEL DRIVE LAYOUT


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FRONT WHEEL DRIVE

On a front wheel drive car, the transmission is usually combined with the finform what is called a transaxle.

Transaxle is a device set up in the transmission gear box, clutch, final drive,in a single unit.

Front wheel drive layouts are those in which the wheels of the vehicle are

Front axles are connected directly to the transmission to provide power to wheels.

This layout is typically chosen for its compact packaging.


11/35FRONT WHEEL DRIVE LAYOUT


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COMPONENTS OF TRANSMISSIONSYSTEM

Planetary Gear Sets Hydraulic System

Oil Pump

Valve Body

Clutches

Band

Seals and Gaskets Torque Converter Governor

Computer Controls
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PLANETARY GEAR SETS

A gear set in which all of the gears are in one plane, grouped aroundeach 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 "ringgear".

By holding any one of the three gear elements motionless, differentratios can be produced between the other two. Planetary gear sets arecommon in automatic transmissions.


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SIDE VIEW


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A clutch is a mechanical device which provides for the transmission of power (therefore usually motion) from one component (the driving member) to anothdriven member).

The simplest application clutches are employed in devices which have two rotshafts.

CLUTCH PACKS


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BANDS

A band is a steel strap with frictionmaterial bonded to the insidesurface.

One end of the band is anchoredagainst the transmission case whilethe other end is connected to aservo.

A flexible metal ring fits aroutside of the clutch housto engage the gears, and release them.


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TORQUE CONVERTER


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TORQUE CONVERTER

A torque converter isa fluid coupling that

is used to transferrotating power froma prime mover, suchas an internalcombustion engine orelectric motor, to arotating driven load.
http://en.wikipedia.org/wiki/Fluid_couplinghttp://en.wiktionary.org/wiki/prime_moverhttp://en.wikipedia.org/wiki/Internal_combustion_enginehttp://en.wikipedia.org/wiki/Internal_combustion_enginehttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Internal_combustion_enginehttp://en.wikipedia.org/wiki/Internal_combustion_enginehttp://en.wiktionary.org/wiki/prime_moverhttp://en.wikipedia.org/wiki/Fluid_coupling


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HYDRAULIC SYSTEM

The Hydraulic system is a complex maze of passages andtubes that sends transmission fluid under pressure to allparts of the transmission and torque converter

It works with some components.

Oil Pump

Valve Body


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OIL PUMP

The transmission oil pump(not to be confused with the pump

element inside the torque converter) is responsible for producingall the oil pressure that is required in the transmission. The oil pumpis mounted to the front of the transmission case and is directlyconnected to a flange on the torque converter housing.


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VALVE BODY

The valve body is the control center of the automatic

transmission. It contains a maze of channels and passages thatdirect hydraulic fluid to the numerous valves which then activatethe appropriate clutch pack or band servo to smoothly shift tothe appropriate gear for each driving situation


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COMPUTER CONTROLS

The computer uses sensors on the engine and transmission tdetect such things as throttle position, vehicle speed, enginespeed, engine load, brake pedal position, etc. to control exashift points as well as how soft or firm the shift shouldbe. Once the computer receives this information, it then sesignals to a solenoid pack inside the transmission


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NON-COMPUTERIZED

TRANSMISSIONS

Governor

Vacuum Modulator

Throttle Cable

Seals and Gaskets


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SEALS & GASKETS

An automatic transmission has many seals and gaskets to controlthe flow of hydraulic fluid and to keep it from leaking out. Thereare two main external seals:

The front seal

The rear seal.


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FRONT & REAR SEAL

The front seal seals the point where the torque converter mountsto the transmission case.

This seal allows fluid to freely move from the converter to the

transmission but keeps the fluid from leaking out. The rear seal keeps fluid from leaking past the output shaft.

A gasket is a type of seal used to seal two stationary parts thatare fastened together.


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GOVERNOR, VACUUM MODULATOR& THROTTLE CABLE

These three components provide the inputs that tell the transmission when toshift.

Governor regulates the mean speed of the engine.

The Throttle Cable simply monitors the position of the gas pedal through acable that runs from the gas pedal to the throttle valve in the valve body.

The Vacuum Modulator monitors engine vacuum by a rubber vacuum hosewhich is connected to the

engine.


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automotive transmission system

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