When it comes to high-performance automobiles, the automatic transmission is the popular option for easy and reliable driving. And that’s why we’re going to describe how automatic transmission works. We will explore the working principles of this complex mechanism in a simple and logical way. For this purpose, we will use the Allison Transmission automatic transmission.
How It Works: Automatic Transmissions
Work automatically on a planetary gear set foundation. In order to understand this process, let’s take a look at the basic parts of planetary gear sets. Planetary gear sets have two input and one output. In an automatic transmission working, the output rotation is drawn from the planet carrier.
The two inputs are connected to the ring and sun gears. Now let’s see what happens to the output speed when we apply different speeds to the inputs.
Here the ring gear is stationary and rotation is given exclusively to the sun gear. As you can see, that causes the carrier to spin. The ring gear is also rotating. At the same speed, the ring and sun spin. In this case, the whole mechanism moves as a single unit. The ring gear speed is increased further.
Turning the sun gear in the opposite direction will result in reverse gear. So the operation of an automatic transmission working is all about transmitting different rotation speeds into the ring and sun gears.
The beauty of automatic transmission:
is that this speed variation can be transmitted simply by engaging a few clutch packs. In the coming sessions, we will see how this is achieved in Allison. Now In an automatic transmission working, the input and output shafts are not connected, rather the intermediate shaft is situated between them. In addition to clutch packs are used for transmitting power. The clutch packs will lock the unit in the case with the stress.
This is the simplest form of automatic transmission. With this in mind, let’s see how 1st gear works. If the 1st clutch pack is applied the input shaft will connect to the intermediate shaft. On the other hand, if the 2nd clutch pack is applied, the ring gear will connect to the case which will make the gear become stationary. Apply both clutch packs together to reach the 1st gear.
The input shaft turns on the sun appliances. Since the ring gear is stationary, with nearly a third of the input speed, the output shaft spins. In another planetary gear set, to attain additional gear ratios. It is clear that apply C1 will always rotate both sun gears at the input shaft speed. The planet carrier of the second batch will turn if we apply C4 as well.
But here is the tricky part:
Now let’s talk more about how an automatic transmission works. This planet carrier is continuously connected with the 1st set ring gear. So, when C1 and C4 are applied together, the ring gear of the output set will turn. The situation is therefore similar to that at the 1st gear at the output set, except that the ring gear also focuses here. The output planet carrier velocity will therefore increase. This means that the speed of the output planet carrier will increase. This is the 2nd gear of the transmission. A hollow shaft is also mounted on the planet carrier.
With a rotating clutch module, the shaft can be connected directly to the input shaft. Take a moment to observe and understand this arrangement – the rest of the process will be easy. With this setup, with a direct drive we can reach the third gear. The ring and sun gears of the output set should move at input shaft speed in order to get a direct drive.
If we apply C1 and C2, this is what happens:
The sun and ring gears will be directly connected to the input shaft. In order to achieve 6th gear just remove C1 and apply C4. Here at the 2nd set, the input rotation is given to the carrier and the ring gear is stationary. This combination gives a very high rotational speed to the sun gear. Thus, we can achieve a high overdrive ratio at the output. The 3rd planetary gear set is required to get the remaining gear ratios.
As shown here, the sun equipment is always linked to the input shaft. And here again, the output of the set is connected to the input of the adjacent set. This means that the C3 is always used to turn the 2nd ring gear. C3 is always applied to the remaining gear ratios.
But for 3rd gear just applies C1 as well. For 5th gear remove C1 and apply C2. The ring gear clutch C5 also is applied to go inverse. Since the planet gear of 2nd set cannot revolve, they will spin as shown here. This will eventually lead to the reverse rotation of the sun gear. Consequently, the final output will be a rotation in the opposite direction. When applying which clutch pack, a transmission control unit will decide.
We hope you did get all the knowledge regarding automatic transmission working and how automatic transmission works. Unlike manual transmissions, a torque converter is needed in the automatic transmissions. We must separate the rotation of the engine from the transmission if the transmission is in gear and we apply the brakes. With a fluid coupling, the torque converter will help accomplish this. The Automatic Transmission Systems will also be a good idea for a 2D animation.