· Web viewThese include the torque converter, valve body, pump, and clutch bands. Automatic transmissions are almost always less energy efficient than manual transmissions, due

Project Report 2013-14 Automatic Transmission System

ACKNOWLEDGEMENT

We proudly utilize this opportunity to express our grateful

thanks and sincere to our project guide Mr. MUJEEB RAHMAN.K

(Instructor in automobile engineering department).

We are grateful very much to Mr. MUHAMMED SALEEM.I.P

(Head of automobile engineering department).

We express our thanks to Mr. NITHIN, Mr. SAJID and other

automobile engineering department staffs for their devoted help and

inspiration for the completion of the project work.

We extend our thanks to all of our friends and classmates

without whose help, this would not have been success.

Dept.of Automobile Engineering 1 JDT Islam Polytechnic Clt-12


PREFACEProject work has an important position in the syllabus of

diploma courses in engineering. By doing this project we got a chance

to apply the knowledge in theory to practical application. By doing

various types of equipment developed under project work will not

only enhance our skill but also aid for the development of the

students.



ABSTRACTAn automatic transmission is a type of motor vehicle

transmission that can automatically change gear ratios as the vehicle

moves, freeing the driver from having to shift gears manually. These

are broadly of two types viz., the semi automatic and fully automatic

ones. In the first type only clutch is operated automatically, the driver

still has to select gears. In the later type which is employed in modern

cars, even the gear are changed automatically by a control mechanism

which is actuated by the accelerator pedal only. In the cars with fully

automatic transmission, there are only two pedals, viz., for braking

and for accelerating.

The present day automatic transmission consist of multi plate

clutches, torque converter and epicyclic gearbox. Automatic

transmission operate basically by controlling vehicle speed and

engine load. Increasing vehicle speed needs changing gears upward,

whereas increasing engine load necessitate change from higher to

lower gears. For the speed factor a sensitive control unit (mechanical,

hydraulic or electrical) is driven off a suitable point beyond

transmission and thus its control action become sensitive to vehicle

speed. The engine load factor is introduced by the position of the

accelerator pedal. Thus the engine load sensitive control unit is

operated by the depression of the accelerator pedal.



INDEX

1. INTRODUCTION

2. COMPARISON WITH MANUAL TRANSMISSION

3. AUTOMATIC TRANSMISSION MODES

4. HYDRAULIC AUTOMATIC TRANSMISSION

TORQUE CONVERTER

PUMP

PLANETARY GEAR SET

VALVE BODY

HYDRAULIC LUBRICATING OIL

GOVERNER

5. COST OF PROJECT

6. CONCLUSION

7. REFERENCE



INTRODUCTION

An automatic transmission (also called automatic gearbox) is a

type of motor vehicle transmission that can automatically change

gear ratios as the vehicle moves, freeing the driver from having to

shift gears manually. Most automatic transmissions have a defined

set of gear ranges, often with a parking pawl feature that locks the

output shaft of the transmission stroke face to keep the vehicle from

rolling either forward or backward. Similar but larger devices are also

used for heavy-duty commercial and industrial vehicles and

equipment. Some machines with limited speed ranges or fixed

engine speeds, such as some forklifts and lawn mowers, only use a

torque converter to provide a variable gearing of the engine to the

wheels.

Besides automatics, there are also other types of automated

transmissions such as a continuously variable transmission (CVT) and

semi-automatic transmissions, that free the driver from having to

shift gears manually, by using the transmission's computer to change

gear, if for example the driver were redlining the engine. Despite

superficial similarity to other transmissions, automatic transmissions

differ significantly in internal operation and driver's feel from semi-

automatics and CVTs. An automatic uses a torque converter instead

of a clutch to manage the connection between the transmission



gearing and the engine. In contrast, a CVT uses a belt or other torque

transmission scheme to allow an "infinite" number of gear ratios

instead of a fixed number of gear ratios. A semi-automatic retains a

clutch like a manual transmission, but controls the clutch through

electro hydraulic means. The present day automatic transmission

consist of multi plate clutches, torque converter and epicyclic

gearbox. Automatic transmission operate basically by controlling

vehicle speed and engine load.

The first automatic transmission was invented in 1921 by Alfred

Horner Munro of Regina, Saskatchewan, Canada, and patented

under Canadian patent CA 235757 in 1923. The first automatic

transmissions using hydraulic fluid were developed by General

Motors during the 1930s and introduced in the 1940 Oldsmobile as

the "Hydra-Matic" transmission. They were incorporated into GM-

built tanks during World War II and, after the war, GM marketed

them as being "battle-tested".



COMPARISON WITH MANUAL TRANSMISSION

An automatic gearbox is one type of motor vehicle transmission

that can automatically change gear ratios as the vehicle moves,

freeing the driver from having to shift gears manually. This

transmission utilizes several key parts, which are not found in a

manual transmission, in order to work properly. These include the

torque converter, valve body, pump, and clutch bands. Automatic

transmissions are almost always less energy efficient than manual

transmissions, due mainly to viscous and pumping losses; both in the

torque converter and the hydraulic actuators. A relatively small

amount of energy is required to pressurize the hydraulic control

system, which uses fluid pressure to determine the correct shifting

patterns and operate the various automatic clutch mechanisms.

Manual transmissions use a mechanical clutch to transmit

torque, rather than a torque converter, thus avoiding the primary

source of loss in an automatic transmission. Manual transmissions

also avoid the power requirement of the hydraulic control system, by

relying on the human muscle power of the vehicle operator to

disengage the clutch and actuate the gear levers, and the mental

power of the operator to make appropriate gear ratio selections.

Thus the manual transmission requires very little engine power to



function, with the main power consumption due to drag from the

gear train being immersed in the lubricating oil of the gearbox.



AUTOMATIC TRASMISSION MODES

Conventionally, in order to select the transmission operating

mode, the driver moves a selection lever located either on the steering

column or on the floor (as with a manual on the floor, except that

most automatic selectors on the floor do not move in the same type of

pattern as a manual lever; most automatic levers only move

vertically). In order to select modes, or to manually select specific

gear ratios, the driver must push a button in (called the shift lock

button) or pull the handle (only on column mounted shifters) out.

Some vehicles position selector buttons for each mode on the cockpit

instead, freeing up space on the central console. Vehicles must have

the modes ordered P-R-N-D-L (left to right, top to bottom, or

clockwise). Prior to this, quadrant-selected automatic transmissions

often used a P-N-D-L-R layout, or similar. Such a pattern led to a

number of deaths and injuries owing to driver error causing

unintentional gear selection, as well as the danger of having a selector

(when worn) jump into Reverse from Low gear during engine braking

maneuvers.

Automatic transmissions have various modes depending on the

model and make of the transmission. Some of the common modes

include:



Park (P)

This selection mechanically locks the output shaft of

transmission, restricting the vehicle from moving in any

direction. A parking pawl prevents the transmission from

rotating, and therefore the vehicle from moving, but the

vehicle's driven wheels may still rotate individually (because of

the differential), as well as the non-driven road wheels may still

rotate freely. For this reason, it is recommended to use the hand

brakes (parking brake) because this actually locks (in most

cases) the wheels and prevents them from moving. This also

increases the life of the transmission and the park pin

mechanism, because parking on an incline with the transmission

in park without the parking brake engaged will cause undue

stress on the parking pin. A hand brake should also prevent the

car from moving if a worn selector accidentally drops into

reverse gear while idling.

A car should be allowed to come to a complete stop before

setting the transmission into park to prevent damage. Usually,

Park (P) is one of only two selections in which the car's engine

can be started, the other being Neutral (N). In many modern cars

and trucks, the driver must have the foot brake applied before

the transmission can be taken out of park. The Park position is

omitted on buses/coaches (and some road tractors) with

automatic transmission (on which a parking pawl is not



practical), which must be placed in neutral with the air-operated

parking brakes set.

Most automobiles require P or N to be set on the selector

lever before the engine can be started. This is typically achieved

via a normally open inhibitor switch (sometimes called a

"neutral safety switch") wired in series with the starter motor

engagement circuit, which is closed when P or N is selected,

completing the circuit (when the key is turned to the start

position), along with any other safety devices which may be

present on newer cars (such as a foot-brake application).

Reverse (R)



This engages reverse gear within the transmission,

permitting the vehicle to be driven backward, and operates a

switch to turn on the white backup lights for improved visibility

(the switch may also activate a beeper on delivery trucks or

other large vehicles to audibly warn other drivers and nearby

pedestrians of the driver's reverse movement). To select reverse

in most transmissions, the driver must come to a complete stop,

depress the shift lock button (or move the shift lever toward the

driver in a column shifter, or move the shifter sideways along a

notched channel in a console shifter) and select reverse. Not

coming to a complete stop may cause severe damage to the

transmission. Some modern automatic transmissions have a

safety mechanism in place, which does, to some extent, prevent

(but not completely avoid) inadvertently putting the car in

reverse when the vehicle is moving forward; such a mechanism

may consist of a solenoid-controlled physical barrier on either

side of the Reverse position, electronically engaged by a switch

on the brake pedal. Therefore, the brake pedal needs to be

depressed in order to allow the selection of reverse. Some

shifters with a shift button allow the driver to freely move the

shifter from R to N or D, or simply moving the shifter to N or D

without actually depressing the button. However, the driver

cannot shift back to R without depressing the shift button, to

prevent accidental shifting, especially at high speeds, which

could damage the transmission.



Neutral / No gear (N)

This disengages all gear trains within the transmission,

effectively disconnecting the transmission from the driven

wheels, allowing the vehicle to coast freely under its own

weight and gain momentum without the motive force from the

engine. Coasting in idle down long grades (where law permits)

should be avoided, though, as the transmission's lubrication

pump is driven by non-idle engine RPMs.

Drive (D)

This position allows the transmission to engage the full

range of available forward gear ratios, allowing the vehicle to

move forward and accelerate through its range of gears.

Overdrive ('D', 'OD')

This mode is used in some transmissions to allow early

computer-controlled transmissions to engage the automatic

overdrive. In these transmissions, Drive (D) locks the automatic

overdrive off, but is identical otherwise. OD (Overdrive) in

these cars is engaged under steady speeds or low acceleration at

approximately 35–45 mph (56–72 km/h). Under hard

acceleration or below 35–45 mph (56–72 km/h), the

transmission will automatically downshift.

Third (3)

This mode limits the transmission to the first three gear

ratios, or sometimes locks the transmission in third gear. This



can be used to climb or going downhill. Some vehicles will

automatically shift up out of third gear in this mode if a certain

RPM range is reached in order to prevent engine damage.

Second (2 or S)

This mode limits the transmission to the first two gear

ratios, or locks the transmission in second gear. This can be used

to drive in adverse conditions such as snow and ice, as well as

climbing or going down hills in winter. It is usually

recommended to use second gear for starting on snow and ice,

and use of this position enables this with an automatic

transmission. Some vehicles will automatically shift up out of

second gear in this mode if a certain RPM range is reached in

order to prevent engine damage.

First (1 or L [Low])

This mode locks the transmission in first gear only. In

older vehicles, it will not change to any other gear range. Some

vehicles will automatically shift up out of first gear in this mode

if a certain RPM range is reached in order to prevent engine

damage. This, like second, can be used during the winter season,

for towing, or for downhill driving to increase the engine

braking effect.



HYDRAULIC AUTOMATIC TRANSMISION

The predominant form of automatic transmission is

hydraulically operated; using a fluid coupling or torque converter, and

a set of planetary gear sets to provide a range of gear ratios. A

hydraulic automatic transmission consist of the following parts:

TORQUE CONVERTER COMPONENTS

The torque converter provides an automatic means of

coupling engine torque to the input shaft of the transmission. The

torque converters three major components are; the pump impeller, the

turbine runner and the stator. The hydraulic fluid in the torque

converter transfers torque through the kinetic energy of the

transmission fluid as it is forced from the impeller to the turbine. The

faster the engine rotates, the greater the torque applied to the turbine.

At low engine speed, the turbine can be held stationary as the force of

the fluids kinetic energy is not great enough to overcome the holding

force of the light brake system application.



PUMP IMPELLER

The impeller is integrated with the torque converter case,

with many curved vanes evenly spaced and mounted inside. A guide

ring is installed on the inner edges of the vanes to provide a path for

smooth fluid flow. When the impeller is driven by the engine

crankshaft; the fluid in the impeller rotates with it. When the impeller

speed increases, centrifugal force causes the fluid to flow outward

toward the turbine.



TURBINE RUNNER

The turbine runner is located inside the converter

case, but is not connected to it. The input shaft of the transmission is

attached by splines to the turbine hub when the converter is mounted

to the transmission. Many cupped vanes are attached to the turbine.

The curvature of the vanes is opposite from that of the impeller vane.

Therefore, when the fluid is thrust from the impeller, it is caught in

cupped vanes of the turbine and torque is transferred to the

transmission input shaft, turning it in the same direction as the engine

crankshaft. A guide ring similar to the impeller is installed to the inner

edge of the vanes.

STATOR

The stator is located between the impeller and the

turbine. It is mounted on the stator reaction shaft which is fixed to the

transmission case. The vanes of the stator catch the fluid as it leaves

the turbine runner and redirects it so that it strikes the back of the

vanes of the impeller, giving the impeller added boost or torque. The

benefit of this added torque can be great as 30% to 50%.The one-way

clutch mounted to the stator allows it to rotate in the same direction as

the engine crankshaft. However, if the stator attempts to rotate in the

opposite direction, the one-way clutch locks the stator to prevent it

from rotating. Therefore, the stator is rotated or locked depending on

the direction from which the fluid strikes against the vanes.

CONVERTER OPERATION



When the impeller is driven by the engine crankshaft,

the fluid around the impeller rotates in the same direction. As impeller

speed increases, centrifugal force causes the fluid to flow outward

from the center of the impeller and flow along the vane surfaces of the

impeller. As speed increases further, fluid is forced out away from the

impeller towards the turbine. The fluid strikes the vanes of the turbine

causing it to rotate in the same direction as the impeller.

After the fluid dissipate its energy against the vanes of the

turbine, it flows inward along the vanes of the turbine. When it

reaches the interior of the turbine, the turbines curved inner surface

directs the fluid at the vanes stator. Fluid strikes the curved vane of

the stator causing the one-way clutch to lock the stator and redirect

fluid at the impeller vanes in the direction of engine rotation,

increasing engine torque.

As the impeller and turbine approach the same speed, fluid

strikes the back of the stator vanes, releasing the one-way clutch and

allows the stator to freewheel. Unless the stator freewheels, being



mounted to the transmission body, fluid will strike the vanes of the

stator and limit engine rpm and upper engine performance.

CONVERTER LOCK-UP CLUTCH

At lower vehicle speeds the torque converter provides multiple

gear ratios when high torque is needed. As the impeller and the

turbine rotate at nearly the same speed, no torque multiplication is

taking place, the torque converter transmits the input torque from the

engine to the transmission at the ratio of almost 1:1. There is,

however, approximately 4% to 5% difference in rotational speed

between the turbine and impeller. The torque converter is not

transmitting 100% of the power generated by the engine to the

transmission, so there is energy loss.

To reduce energy loss and improve fuel economy, the lock-up

clutch mechanically connects the impeller and the turbine when the

vehicle speed is about 37 mph or higher. When the lock-up clutch is

engaged, 100% of the power is transferred through the torque

converter. The lock-up clutch is installed on the turbine hub between



the turbine and the converter front cover. Hydraulic pressure on either

side of the converter piston causes it to engage or disengage the

converter front cover. A set of dampening springs absorb the torsional

force upon clutch engagement to prevent shock transfer. The friction

material bonded to the lock-up piston is the same as that used on multi

plate clutch disk in the transmission.

LOCK-UP OPERATION

When the lock-up clutch is engaged, it connects the impeller and

turbine. Engaging and disengaging the lock-up clutch is determined

by which side of the lock-up clutch the fluid enters the torque

converter. The difference in pressure on either side of the lock-up

clutch determines engagement or disengagement. Fluid can either



enter the body of the converter behind the lock-up clutch engaging the

clutch, or in front of the lock-up clutch to disengage it.

The fluid used to control the torque converter lock-up is also used to

remove heat from the converter and transfer it to the engine cooling

system through the heat exchanger in the radiator.

PUMP

Not to be confused with the impeller inside the torque converter,

the pump is typically a gear pump mounted between the torque

converter and the planetary gear set. It draws transmission fluid from

a sump and pressurizes it, which is needed for transmission

components to operate. The input for the pump is connected to the

torque converter housing, which in turn is bolted to the engine's

flywheel, so the pump provides pressure whenever the engine is

running and there is enough transmission fluid. The outer gear is

turned by the inner gear, and as the gears rotate, fluid is drawn up

from the sump on one side of the crescent and forced out into the



hydraulic system on the other side. Early automatic transmissions also

had a rear pump, allowing push-starting.

PLANETARY GEAR

Epicyclic gearing or planetary gearing is a gear system consisting of one or more outer gears, or planet gears, revolving about a central, or sun gear. Typically, the planet gears are mounted on a movable arm or carrier which itself may rotate relative to the sun gear. Epicyclic gearing systems also incorporate the use of an outer ring gear or annulus, which meshes with the planet gears. Planetary gears (or epicyclic gears) are typically classified as simple and compound planetary gears. Simple planetary gears have one sun, one ring, one carrier, and one planet set. Compound planetary gears involve one or more of the following three types of structures: meshed-planet (there are at least two more planets in mesh with each other in each planet train), stepped-planet (there exists a shaft connection between two planets in each planet train), and multi-stage structures (the system contains two or more planet sets). Compared to simple planetary gears, compound planetary gears have the advantages of larger reduction ratio, higher torque-to-weight ratio, and more flexible configurations. A compound epicyclic planetary gearset, whose bands and clutches are actuated by hydraulic servos controlled by the valve body, providing two or more gear ratios.



The operation of planetary gear set is summarized below.

Different speeds and rotational directions can be obtained by holding

one of the planetary members in a fixed position, providing input

torque to another member, with the third member used as an output

member.

FORWARD DIRECTION

When the ring gear or sun gear is held in a fixed position and

either of the other members is an input member, the output gear

rotational direction is always the same as the input gear rotational

direction.

Reduction When the internal teeth of the ring gear turns clockwise, the

external teeth on the pinion gears walk around the fixed sun gear



while rotating clockwise. This cause the carrier to rotate at a reduced

speed.

Overdrive

When the carrier turns clockwise, the external toothed pinion

gear walk around the external toothed sun gear while rotating

clockwise. The pinion gears cause the internal toothed ring gear to

accelerate to a speed greater than the speed greater than the carrier

speed in a clockwise direction.

REVERSE DIRECTION

Whenever the carrier is held and either of the other gears are

input members, the output gear will rotate in the opposite direction.

With the carrier held, when the external toothed sun gear turns

clockwise, the external toothed pinion gears on the carrier idle in

place and drive the internal toothed ring gear in the opposite direction.

DIRECT DRIVE (ONE-TO-ONE RATIO)

When any two members are held together and another

member provides the input turning force, the entire assembly turns at

the same speed as the input member.

Now the gear ratio from a single planetary set do not give us

the desired ratios which take advantage of the optimum torque curve

of the engine. So it is necessary to use compound planetary gear sets.

HOLDING DEVICES FOR PLANETARY GEAR SET

There are three type of holding devices used in the planetary gear

set. Each type has its specific design advantage. The three include

multi plate clutches /brakes, brake band and one- way clutch.



Multi plate Clutch: Hold two rotating planetary components.

Roller or Sprag One- Way Clutch: Hold planetary components in

one rotational direction and freewheels in the other direction.

Multi plate Brake and Brake Band: Holds planetary components

to the transmission case.

The multi plate clutch multi plate brake are the most common of

the three types of holding device; they are versatile and can be

modified easily by removing or including more friction discs. The

brake band take very little space in the cavity of the transmission

housing and has a large surface area to create strong holding force.

One- way clutches are small in size and release and supply quickly,

giving good response for up shift and down shifts.

MULTI PLATE CLUTCH

The multi plate clutch connected two rotating components of the

planetary gear set. The Simpson planetary gear unit uses two multi

plate clutches, the forward clutch and the direct clutch. Each clutch

drum is slotted on the inner diameter to engage the steel plates and

transfer turning torque from the engine. The drum also provides the

bore for the clutch piston.

Friction discs are steel plates which have friction material

bonded to them. They are always located between two steel plates.

The friction disc inner diameter is slotted to fit over the splines of

the clutch hub.



Steel plates are slotted on the outer diameter to fit the slots of the

clutch drum or transmission case. They a smooth surface for the

friction discs to engage with. Steel plates can be installed next to

one another to give a specific clearance for the clutch pack.



MULTI PLATE OPERATION

Because this assembly rotates while the vehicle is in motion, it

present a unique challenge to ensure pressurized fluid reaches the

clutch and hold the clutch engaged for many tens of thousands of

miles of service. Oil seal rings seal the fluid passage between the

clutch drum and oil pump stator support and transmission center

support.

Seals are mounted on the piston inner and outer diameter which

seal the fluid applying the piston. A relief ball valve is housed in the

piston body to release hydraulic fluid when the clutch is released. As

the drum rotate, some fluid remains behind the piston and centrifugal

force causes the fluid to flow to the outer diameter of the drum

causing pressure. This pressure may not fully engage the clutch,

however, it may reduce the clearance between the disc and the metal

plates, promoting heat and wear.

The relief ball valve is designed to allow fluid to escape when

pressure is released. As pressure drops, centrifugal force causes the

ball to move away from the valve seat, allowing to fluid to escape so

the piston can be seated, providing proper clearance between the disc



and steel plates. The brake band perform the same function as the

multi plate brake is located around the outer circumference of the

direct clutch drum. One end of this brake band is anchored to the

transmission case with a pin, while the other end contacts the brake

piston rod which is controlled by hydraulic pressure and spring

tension.

The band is applied by a piston and piston rod located in the

transmission case. When hydraulic pressure is applied to the piston,

the piston moves to the left compressing the outer spring. The inner

spring transfer the motion from the piston to the piston rod, applying

pressure to the end of the brake band. As the inner spring compresses,

the piston comes in direct contact with the piston rod shoulder and a

high frictional force is generated between the brake band and drum.

The brake band clamps down on the drum which causes the drum and

a member of the planetary gear set to be held to the transmission case.

When the pressurized fluid is drained from the cylinder, the

piston and piston rod are pushed back by the force of the outer spring

so the drum is released by the brake band.

ONE- WAY CLUTCH AND BANDS

To effect gear changes, one of two types of clutches or bands

are used to hold a particular member of the planetary gear set

motionless, while allowing another member to rotate, thereby

transmitting torque and producing gear reductions or overdrive ratios.

These clutches are actuated by the valve body their sequence

controlled by the transmission's internal programming. Principally, a



type of device known as a sprag or roller clutch is used for routine up

shifts/downshifts. Operating much as a ratchet, it transmits torque

only in one direction, free-wheeling or "overrunning" in the other.

The advantage of this type of clutch is that it eliminates the sensitivity

of timing a simultaneous clutch release/apply on two planetaries,

simply "taking up" the drive train load when actuated, and releasing

automatically when the next gear's sprag clutch assumes the torque

transfer. The bands come into play for manually selected gears, such

as low range or reverse, and operate on the planetary drum's

circumference. Bands are not applied when drive/overdrive range is

selected, the torque being transmitted by the sprag clutches instead.

Bands are used for braking. The brake band perform the same

function as the multi plate brake is located around the outer

circumference of the direct clutch drum. One end of this brake band is

anchored to the transmission case with a pin, while the other end

contacts the brake piston rod which is controlled by hydraulic

pressure and spring tension.



The band is applied by a piston and piston rod located in the

transmission case. When hydraulic pressure is applied to the piston,

the piston moves to the left compressing the outer spring. The inner

spring transfer the motion from the piston to the piston rod, applying

pressure to the end of the brake band. As the inner spring compresses,

the piston comes in direct contact with the piston rod shoulder and a

high frictional force is generated between the brake band and drum.

The brake band clamps down on the drum which causes the drum and

a member of the planetary gear set to be held to the transmission case.

When the pressurized fluid is drained from the cylinder, the

piston and piston rod are pushed back by the force of the outer spring

so the drum is released by the brake band.

VALVE BODY

Hydraulic control center that receives pressurized fluid from the

main pump operated by the fluid coupling/torque converter. The

pressure coming from this pump is regulated and used to run a

network of spring-loaded valves, check balls and servo pistons. The

valves use the pump pressure and the pressure from a centrifugal

governor on the output side (as well as hydraulic signals from the



range selector valves and the throttle valve or modulator) to control

which ratio is selected on the gear set; as the vehicle and engine

change speed, the difference between the pressures changes, causing

different sets of valves to open and close. The hydraulic pressure

controlled by these valves drives the various clutch and brake band

actuators, thereby controlling the operation of the planetary gear set to

select the optimum gear ratio for the current operating conditions.

However, in many modern automatic transmissions, the valves are

controlled by electro-mechanical servos which are controlled by the

electronic engine control unit (ECU).

HYDRAULIC & LUBRICATING OIL

Is called automatic transmission fluid (ATF), this component of

the transmission provides lubrication, corrosion prevention, and a

hydraulic medium to convey mechanical power (for the operation of

the transmission). Primarily made from refined petroleum, and

processed to provide properties that promote smooth power

transmission and increase service life, the ATF is one of the few parts

of the automatic transmission that needs routine service as the vehicle

ages.



GOVERNOR

The governor is a clever valve that tells the transmission how

fast is the car is going. It is connected to the output, so the faster the

car moves, the faster the governor spins. Inside the governor is a

spring loaded valve that opens in proportion to how fast the governor

is spinning, the faster the governor spins, the more the valve opens.

Fluid from the pump is fed to the governor through the output shaft.

The faster the car goes, the more the governor valve opens and the

higher the pressure of the fluid it lets through.



COST OF PROJECT BILL OF MATERIAL

Sl. No NAME OF MATERIAL COST IN RS.

1 Gear box assembly 6000

2 Stand 1350

3 Paint 200

TOTAL 7550

LABOUR COST

Welding= 600

Other expense=450

Total cost= Material cost+ Labour cost+ Other expense

= 7550+600+450

=8600



CONCLUSIONAutomatic transmission technology is more widely accepted. In

fact, long-term tests under normal operating conditions have shown

that this type of gearbox provides either increased performance or at

least the same performance as the manual transmissions. Carriers

noted only two major disadvantages of automatic transmissions,

compared to manual higher weight and a higher initial cost.

With the absence of the gearshift and the clutch, automatics

offer stress-free driving to discerning customers who have to

constantly change gears in the stop-and-go type traffic. One reason for

the adoption of automatic transmission is the scarcity of professional

drivers. This new technology is easier to use than conventional

manual gearboxes, especially if a majority of a fleet’s runs are on

roads that are relatively level or have few steep rises. The second

reason is the potential gain in energy efficiency. Results indicate a

substantial increment in efficiency. In coming years ‘Automatic

Power Transmission’ can prove to be a major factor that will make

driving a more luxurious and stress free.



REFERENCE

www.wikipedia.org

www.autoshop101.com

www.manualversusautomatic.com

www.howstuffworks.com

www.scribd.com


Documents

· Web viewThese include the torque converter, valve body, pump, and clutch bands. Automatic transmissions are almost always less energy efficient than manual transmissions, due