What is automatic transmission? Any idea! In this article, we will explore automatic automation, along with types, advantages, disadvantages, etc.
The automatic transmission systems are also known as the self-shifting transmission or dual pedal technology.
It is a multi-speed transmission system that doesn’t require input from the driver for changing gears under normal driving conditions.
If you are not getting it, you definitely may have driven the scooty, mopeds. They don’t need to shift the gears manually they will automatically get adjusted as the vehicle propels.
In the year of 1934 the semi-automatic transmission vehicle were released by the General Motors and REO. They had some improvements over the manual transmission but still there was a need of clutch to change the gears.
Later the General Motors used the hydraulically controlled planetary gearbox allowing the gears to shift depending upon the vehicle travel’s speed.
There are different categories of automatic transmission systems. We will see each of them in short details.
This really a complex system and it has many parts by which the whole system works properly.
There are many parts in the automatic transmission.
The main parts are as follows,
It has four main parts
Pump or impeller is directly connected to the flywheel and in case crankshaft rotates, impeller will also rotate. This impeller handled a working fluid.
Turbine is not directly connected to the impeller and it is indirectly connected to the impeller by the working fluid. So, as the turbine and impeller is not directly connected, both can run at different speed.
When impeller rotates, it sends working fluid to the turbine. This working fluid again come back to the impeller by a starter.
Torque converter clutch helps to engage and disengage between turbine power generation to the transmission.
As the name suggests, planetary gear means a combination of different kinds of gears like,
Let’s see the working principle of an automated transmission system in simple way!
Start of the engine and power is produced.
This power is transferred to the pump of the torque convertor.
This power is further transferred to the turbine of torque converter with the help of transmission fluid.
There is a stator which helps the transmission fluid back to the pump from the turbine.
When the turbine rotates, the shaft where turbine mounted, also rotates. This shaft is connected to the planetary gear of the transmission system. Power is transmitted to the 1st set of planetary gears.
Now, clutches are taking part to engage or disengage as well as provide different gear ratio in the transmission system.
Now, entire this process is explained with a simple animated video by LearnEngineering,
There are some common types of automatic transmission systems such as hydraulic automatic. But popularly known transmission systems are,
Let’s take a look at the history of automatic transmission.
The continuously variable transmission system (CVT) is the one which can change the gears in a continuous range seamlessly. Compared to the other transmission systems this one gives more range and flexibility. This characteristic of the continuously variable transmission allows the engine to run at constant RPM while vehicle is moving at varying speeds.
The CVT used pulleys or gears arrangements instead of those traditional steel gears. The continuously variable transmission system is mainly focused on fuel efficiency and continuous acceleration.
So, there are some types of continuously variable transmission systems according to the use.
The pully based CVT is the most common type of the continuously variable transmission systems. It uses a V-belt that runs between the two diameter varied pulleys.
The Toroidal based CVTs were used in the Nissan centric in 1999. It consists of the discs and rollers.
Like example when the rollers axis will be perpendicular to the axis of disc the effective diameter will be same and it will give 1:1 drive ratio.
For getting other ratios rollers will be moved along the axis of discs. So, by moving the rollers the ratios can be changed.
Using toroidal CVT is advantageous because of the ability to withstand the high torque as compared to the pully-based.
As the name suggests it has series of one way ratches. They have the ON and OFF characteristic so; this one is not in continuous operation that contradicts the CVT principle.
The hydrostatic-based continuously variable transmission uses a variable displacement pump and the hydraulic motor.
Hence, the transmission converts the hydraulic pressure generated into the rotation of the output shaft.
If we compare the hydrostatic CVTs to others, the hydrostatic ones are expensive than the others. There are some advantages of the hydrostatic like below.
In case of the cone CVT the drive ratio can be varied by moving the wheel or belt up and down the axis of conical rollers.
It is also known as the planetary CVT. The gear ration in this arrangement will be changed by tilting the axes of spheres in continuous way and providing different contact radii and turning drive input and out discs.
Infinitely variable transmission
Some CVT arrangements are able to get an infinite range of low gears. That is the reason why they are known as infinitely variable transmission systems.
In case, the output shaft speed equals to the difference between the other two speeds, infinitely low drive ratios are created in an epicyclic CVT.
The dual clutch transmission is sometimes also known as the twin clutch transmission system.
Basically, there are two shafts with own clutch for gear shifting. One of them is equipped with even numbered gears and other one is odd numbered gears.
So, the DCT can pre-select an odd gear while the vehicle is moving forward with even gear. DCT’s can shift gears several times faster than the manual transmission system.
Here are some applications in some cars of dual-clutch transmission systems.
The automated manual transmission system (AMT) also known as the clutch-less manual transmission system.
This one is based on the mechanical design like the build of a conventional manual transmission but also uses automation to operate the clutch or gear shifting.
The operation of the automated manual transmission system is when driver selects the desired gear with transmission shift lever.
While the sensors and actuators will be connected to ECU that will automatically operate the clutch to match the revs and re-engage wherever necessary. It is done in milliseconds of time.
The applications of the automatic manual transmission system are wide and still used in lots of cars.
Now we have known all the types of automatic transmission systems.
There all are types of automatic transmission, hence, is simple language these all are good. Now, if we have to choose, anyone of them, then what to choose?
Well, it’s a tricky question as it depends on the person to use and prospective of that person.
Let’s see the differences between an automatic transmission and manual transmission.
Let’s see the main difference between automatic transmission vs manual transmission for basic understanding.
|Automatic Transmission||Manual Transmission|
|In an automatic transmission, gear shifting is not required frequently||In a manual transmission, gear shifting is required frequently|
|Easy to drive||Difficult to drive|
|Very expensive||Less expensive comparative to automatic transmission|
|Manufacturer include this transmission in the higher models||It starts with car basic models.|
|Fuel efficiency is slight low comparative to manual transmission||Fuel efficiency is better than automatic transmission.|
|Maintenance cost is little high||Maintenance cost is low comparative to automatic transmission.|
|For high slope area, vehicles maintain in manual mode instead of automatic mode.||High slope area, manual transmission is preferable.|
Now let’s take a look at advantages and disadvantages of the automatic transmission systems.
Easier to use
The main advantage of the automatic transmission systems is easier to use and convenience of drive. Though there is no rocket science learning to drive the manual transmission system car but still the practise is needed to drive. The automatic transmission systems takes pretty much less time for learning compared to the manual ones.
Better for hill areas
If you are not experienced driver you will definitely find it difficult to navigating through the steep inclines of hills. The automatic ones take care of these issues and operate efficiently.
Easier to use in high traffic conditions
The heavy traffic is one of the most irritating scenes especially for manual transmission vehicles. Because of need of changing the gears and operating clutch continuously. The automatic system is free from all of these issues and driver can easily control and navigate through the traffic.
The automatic transmission systems are kind of safer than the manual ones. Because of the easier way of driving and navigating easily through any conditions the automatic transmission systems are safer.
The cost of automatic vehicles are more, basically the initial cost is higher as compared to the manual systems. The complexity increases with the automatic ones and they become costly.
As the automatic systems are more complex the maintenance required is also more than the manual transmission systems.
So, these are the advantages and disadvantages of the automatic transmissions systems. The inclusion of modern technologies is making automatic transmissions even better and the cost is expected to come down in coming time.
Hence, we have got a basic idea about automatic transmission system along with different types, advantages, etc.
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