That's a pretty interesting question

This debate has been present for the last seven decades

Manual and automatic transmissions are completely different technologies

Which use different configurations and principles

one is based on a simple grear pair while the other is based on a

planetary gear set one uses a torque

converter while the other uses a clutch

pack we will do a logical comparison of

these technologies in this video but

first let's understand the basic science

of transmission an internal combustion

engine produces useful torque and power

only during a certain speed range

due to this inherent problem of IC

engines controlling the drive wheel

speed by directly connecting them to the

engine is not a clever idea such an

approach will give the engine of very

low efficiency

rather we need a transmission in between

so that the engines rpm can always be in

the maximum efficiency range the

transmission takes care of the speed

variation of the drive wheels first let

us see how the speed variation is

achieved in a manual transmission a

manual transmission is a collection of

gear pairs

it has three sections

input intermediate shaft and output

the input is connected to the

intermediate shaft so the intermediate

shaft always rotates at a constant speed

the intermediate shaft is then connected

to the output gear set you can see that

the output gears will turn at different

speeds due to different gear ratios

however the output gears are not fixed

with the output shaft and you can even

see a gap between the output gears and

shaft if we connect only one output gear

to the shaft the shaft will have the

speed of the connected gear

for this the main shafts gears have a

synchronizer cone teeth arrangement

a hub is connected to the shaft and a

sleeve slides over it

just by moving this sleeve you will be

able to connect the gear and shaft

it might seem like a simple mechanism

however during an actual operation the

hub and gear will be rotating at

different speeds and the sleeve gear

connection is not possible as they do so

first let's make their speed the same

for this we must discontinue the power

flow to the transmission the use of

clutch pack comes here

by disengaging the clutch pack the power flow to the gear

set is discontinued

now a synchronizer ring with a friction

cone can help to match the speed of gear

with the sleeve

when there is no power flow pushing the

synchronizer ring against the gear will

help match the speed of the gear to the

hub

now we can have a smooth connection

after the connection clutch pack is

engaged

so every time you need to change the

gear you must disengage the clutch this

also means power discontinuation and an

Associated speed drop during the gear

change this is why a manual transmission

drive is never a smooth experience now

let's see how an automatic transmission

is different from manual transmission

automatic transmission was developed to

overcome the power discontinuation

problem in manual transmission and it

uses a planetary gearset arrangement

rather than a simple gear pair

you can see that a planetary gearset has

two inputs and one output

the basic principle of automatic

transmission is simple just vary these

two input speeds and you will get

different output speeds

to achieve this objective let's

introduce one more planetary set

the output of the second

connected with one of the inputs of the

first set in simple words the carrier of

the second set and the ring gear of the

first set are a single unit this forms

an interesting mechanism and is the

simplest automatic transmission possible

to clutch packs are introduced to arrest

the motion of the ring grears

when the clutch pack is pressed the

corresponding ring gear will be

stationary and carrier will rotate

when the first clutch is pressed the

green ring gear is stationary and we

will get the first gear

if we can turn the green ring gear the

output speed will increase to achieve

this you must release the first clutch

and engage the second clutch the green

ring gear will rotate as it is connected

to the carrier of the second set

it is worth noting that the first clutch

is being released at the same time that

the second clutch is engaged so there is

no loss in power transmission

for different output speeds are possible

with two planetary set arrangement to

learn the details of it check out our

detailed video on automatic transmission

by using three planetary gear sets in

series we will be able to achieve six

different speeds and a reverse the

beauty of the automatic transmission is

that by engaging the proper two clutch

packs we can achieve different output

speeds

now let's compare these two technologies

directly as discussed in the automatic

transmission there is no abruption of

power flow so you will get a smooth

driving experience computer controlled

operation of the automatic transmission

makes the driving even simpler it is

clear that the manual transmission

technology is much simpler than the

automatic it has fewer components and is

easier to repair on the other hand

automatic transmission is a tightly

packed arrangement when it comes to

heavy duty operations manual

transmissions offer more durability due

to this reason almost eighty percent of

heavy duty trucks use manual

transmissions

the way automatic and manual

transmission handles the condition of

braking is quite different and

interesting

in manual transmission driving before

you press the brake pedal the clutch

pedal must be pressed completely this

way the engine rotation and wheel

rotation are separated completely and

the sudden cease of the wheel will not

be transmitted to the engine

however there is no clutch pedal in an

automatic transmission car so to

separate the engine rotation from the

transmission a torque converter is used

this is a fluid coupling which allows

slippage so a torque converter helps

automatic transmission handle the

braking scenario without the need of a

clutch pedal however a torque converter

is a good heat generator which in turn

reduces efficiency of the vehicle as a

result automatic transmission vehicles

tend to become less fuel-efficient than

manual vehicles however the modern

torque converters have overcome this

problem it is our hope that the next

time you plan to purchase a four-wheeler

you will be able to choose the proper

transmission technology according to

your needs to miss our video on DSG

transmission which has the best features

of automatic and manual transmissions

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