Some technologies are easier to understand with the help of 3D animation.
But, what about the 6-Speed automatic transmission from Allison.
To visualize and understand this beautiful planetary gear set mechanism,
a 2D animation will be ideal.
You can consider this 2D drawing as a cross section of the 3D model.
A planetary gear set has 2 inputs and 1 output.
If you properly understand working of a planetary gear set,
you can easily understand automatic transmissions from the 2D animation.
The essence of the planetary gear set is that
just by giving different speeds to the ring and sun gears,
you will be able to get different speeds at the output.
The beauty of automatic transmissions lies
in how these different input speeds are transmitted.
Let's see it in the 2D animation.
This 3D planetary set is represented in 2D as shown.
In an automatic transmission,
the input and the output are not directly connected.
They are connected through an intermediate shaft as shown.
Now, a small suggestion before you proceed.
You will be able to explain all seven gears by yourself
by pausing the video for a moment and understanding the mechanism.
Please try that at every single gear.
You will be amazed by the brilliance of this mechanism.
If you press clutch C1,
the input will be connected to the sun gear.
If you press clutch C5, the output ring gear will be stationary.
This will result in the first gear.
Now let's add one more gear set.
Here comes the tricky part.
The carrier of this set is connected to the ring gear of the first set.
This simply means that
the output of the second set is connected to the input of the first set.
Think for a moment about what happens when you apply C1 and C4.
Since C4 is applied, the ring gear of the second set will be stationary.
This makes the carrier turn.
This carrier is connected to the ring gear of the first set.
So, the ring gear of the first set will also turn.
This, in turn, will increase the output speed
or we will get the second gear.
To obtain a fourth gear or direct drive, a rotating clutch module is also used.
We know that for a direct drive,
both the sun and the ring gear should rotate at the input speed.
If we press C2 and C1 together, this is what happens.
In the very same mechanism,
if you apply C2 and C4 you will get very high speed at the output.
Think for a moment and try to understand this.
It is clear that the carrier of the second set will turn at the input speed.
However, here the ring gear is stationary.
This makes the sun gear turn at almost three times the speed of the input.
Eventually,
a very high output speed is obtained.
One more gear set is used to obtain the remaining gear ratios.
However, the sun gear of this set is not connected to the shaft.
Instead, it is connected to the rotating clutch module.
So, this sun gear will always turn at the input speed.
And here again,
the output of the set is connected to the input of the adjacent set.
For the remaining gear ratios, C3 is always applied.
This means that the brown carrier or ring gear of the second set
will turn at one-third of the input speed for the remaining cases.
For the third gear, apply C1 as well.
For the fifth gear, apply C2 along with C3.
The reverse is an interesting mechanism.
Here, C5 is applied along with C3.
So here, the carrier of the second set is stationary.
This means that the planet gears of this set will not be able to revolve
and that they will simply spin.
This spin is in the same direction as the input.
This planetary spin will make
the corresponding sun gear spin in the opposite direction.
As a result, the output sun gear will also turn in the opposite direction
and we will get the the reverse gear.
We hope that you enjoyed the brilliance of the Allison transmission mechanism.
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