Which is better? Manual or automatic transmission?
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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