Dual Clutch v/s CVT v/s Conventional manuals
Currently, there are a lot of car manufacturers moving towards automatic transmission to make our lives a lot easier. Cars were dream for a person for yesterday, now which has become a symbol of status, lifestyle, fun, adventure for us in day-to-day life.
So now moving towards our competition between this three main competitors, who are of course for this current time are DCT (dual clutch transmission), CVT (continuously variable transmission) and the conventional manuals (operated by foot and gear levers).
Let’s start things slowly now.
DCT is a transmission system which uses two clutches instead of one to shift the gears. Means, for 1,3,5,7 gears there is one clutch and another one is to operate 2, 4, 6 and reverse in a typical 7-speed gearbox. Both the clutches are always ready to shift gears as fast as possible, means if you’re in 1st gear, the another clutch is ready to operate the 2nd gear. When your ECU (engine control unit) detects that you’re in the correct range of shifting, it changes the ratio without even giving you a jerk. This gearbox is very smooth and even very reliable for high torque carrying situations. The German manufacturers use this technology widely. You can find it in VW Polo GT-TSi, Vento TDI AT, Jetta 2.0 Highline TDI; Skoda Octavia, Rapid Elegance AT, Superb; Audi A6,Q3 etc..
A figure showing the comparison between conventional manuals vs DSG is attached below. Here you can clearly see in the red and pinkish line that the DSG shifts without any drop in power or torque, as the clutches are continuously in contact with each gear ratios, so that shifts without full engine cutting from the transmission system. Where in the other hand, you can clearly see the dark green line showing fall in power while shifting gears in conventional manual gearbox, here driver is depressing the clutch and disengaging the engine from drivetrain, means no power will be transmitted while that time, and again the engine will be connected with the drivetrain, so this reduces the efficiency of engine and increases the engine power wastage.
Now comes CVT in the picture…
Honda City, Jazz; Audi A4; Nissan Micra etc comes with CVTs now. Even 2-wheelers come with CVTs, i.e. Activa, Deo and many more. First thing first, how it works? It’s complicated to understand it on paper but; let’s try it. You all have seen the belt and pulley mechanism on lathe and other machines. They have 3-4 slots to fit the belt in them. Now to change the speed ratio you change the slots, so imagine a hydraulic system with brain that do the same thing for you without even your influence. Yes, CVT is a modern belt-pulley drive but with much more ratios than 3-4, it has a hydraulic system which sense the speed and load and as per that it changes the ratio to get the best performance from engine and maximum efficiency at the same time. Unlike DCT, they are cheaper but can transmit limited amount of torque, as it has belt and slipping does takes place. CVT gives you freedom to find the best comfort zone of engine, on a certain RPM range; you may get different ratios, which means it gives you efficiency when you want it and performance when you need it. It also doesn’t let you know when the ratio is changed. Actually, CVT do not contain any GEARS to work with, they change diameters and the work is done for you.
The conventional manuals..
Ah, finally on our favourite thing, which is fully in our control. Depress the clutch, change the gear, put the clutch back and you’re good to go repeating the process again and again. And in the traffic condition, Imagine yourself holding the clutch pedal for hours, and imagine the half-clutch driving, which helps your clutch to kill itself. It is the cheapest among all the gearboxes to buy, but as shown in figure, it reduces efficiency and increase wastage of engine power. It helps to increase stress level in humans too.
Automated Manuals.. Or so called (A-MTs)
In this system, the clutch is pressed by the hydraulic system instead of your limbs. The system does all the jobs that your legs do to disengage the drivetrain from engine. You just need to press the button or pull/press the lever mounted on steering (paddle shifter) or mounted on the place of conventional gear lever. Used in Tata Nano; Suzuki Alto no-a-days.
+VEs of DCT:-
- Lightning fast shifts, that means fast pickup for racing and fun
- Can work with even high torque applications
- Both hand always plays with steering for batter control on car
+VEs of CVT:-
- Fewer parts means low cost
- Good acceleration without wasting power
- Smooth shifting and step less ratios provide you ride comfort
+VEs of Manuals:-
- Involving for the driver
- More fun to drive as the driver stay connected to the whole car while driving
- Can hold gears unless the driver changes himself
- Cheapest among all
Now what about negatives?
-VEs of DCT:-
- High technology involved means higher risk of failure
- Heavier than conventional ATs
4. If you crash the gearbox, start looking for another car as it may lead you to heart attack by its repairing bill.
-VEs of CVT:-
- Boring in one word
- Rubbery shifting felt while sudden acceleration
- Belt gets worn out in nearly 50k kms
-VEs of conventional Transmission:-
- The clutch, hold that little thing in the stop and go traffic and your face will tell the angry emotions inside you
- Power loss while shifting
In short what to buy?
If you got money and buying a car for a huge smile on your face go to Dual shift box. Porsche, Audi, BMW provides DSG, PDK etc named transmission boxes, which are ultimately the DCT (dual clutch gearbox). Which gives you continuous power delivery without even a jerk.
If you’re a person like me with less money in pocket but want an automatic and can manage to drive with good performance and efficiency, go for CVT options. They provide excellent fuel-economy and good drive-ability, but again it has some rubber-band feeling in it, try not to go hard on the gas paddle.
And then, most loved manuals are there in market for us to connect us with the car just like we connect our phones to charger after it shows low battery sign. They are fun to drive. They are reliable; you won’t find yourself in the middle of the road for the failure in the transmission which could be in the case of DCT, as they are not yet tested to their bones yet in our country.
The new technology, which is AUTOMATED Manuals, is cheaper than Dual clutches, and helps you to shift gears without any efforts. Which is also fun to drive. Yet, it also disengages the drivetrain from engine so they are also far away from the competition of CVTs and DCT, but they do the work for you.
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