Automatic Transmission (AT) – TC / CVT / DCT / AMT: All You May Want To Know of AT!

Figoian · Sep 17, 2018

If you are in one of the busy, populous cities of India and driving a car, you must have already developed a knee pain! If you are not, try Bangalore once!! Traffic is incredibly increasing every day for every obvious (and unobvious) reasons and daily commuting is a real pain in the “legs” [frustration]

So, most motorist, if not all would dream of AT at least to have a painless daily commuting.

Automatic Transmission (AT) – While most countries have AT has the most preferred option and in some countries, it can be the only option and MT would only be made to order basis, India is an exception for very well-known reasons. Cost of the product, Availability of such options, and most importantly the favorite question of the country, FE! And there are some who prefer Drive Fun to Ease, which is only with MT. Yes, in India… at least this community would agree to it. But times are changing, manufactures are addressing these points and coming out with options. It’s no more a monopoly, be it about brand, or product. Such a competition is indeed healthy for the consumer.

Today’s auto market will surprise you (in fact puzzle you!) with multiple options in every segment. But will you be able to choose the right one you want? For most people, Automatic Transmission is just AT. Well, it’s not just that. There are number of different technologies within and has it’s own difference, pros and cons. This thread is meant to address you from that perspective. Let’s try and understand the Automatic options available today and which one fits you better.

The broader options available on AT in India today are TC / CVT / DCT / AMT. Let’s detail each of it and you add more as what you know about it.

Torque Converter (TC) - The predominant form of automatic transmission is hydraulically operated; using a fluid coupling or torque converter, and a set of planetary gearsets to provide a range of gear ratios. (Source – Wikipedia). It's one of the traditional and conventional AT system present in modern day too and has it’s own share of cars on sale now.

Pros – Smoother shifts; linear power delivery
Cons – Old school technology; expensive; low FE
Cars Today – Ford Ecosport (2018); Suzuki Ciaz (2018),; Hyundai Verna (2017)

Go for it if you want – A simple and smoother Automatic Car and ready to run often to Fuel Pumps

Continuously Variable Transmissions (CVT) – A fundamentally different type of automatic transmission is the continuously variable transmission, or CVT, which can smoothly and steplessly alter its gear ratio by varying the diameter of a pair of belt or chain-linked pulleys, wheels or cones. Some continuously variable transmissions use a hydrostatic drive — consisting of a variable displacement pump and a hydraulic motor — to transmit power without gears. CVT designs are usually as fuel efficient as manual transmissions in city driving, but early designs lose efficiency as engine speed increases. A slightly different approach to CVT is the concept of toroidal CVT or infinitely variable transmission (IVT). These concepts provide zero and reverse gear ratios. (Source – Wikipedia)

In essence, CVTs doesn’t have any number of fixed gears, nor will need a clutch in general. Since there is no real shift, the experience is smooth as butter with no jerk or head nods even if you floor the pedal.

Pros – Butter smooth shifts or no shifts; linear power delivery; better FE;
Cons – Expensive than TC; Rubber band effect
Cars Today – Honda City, Jazz; Suzuki Baleno

Go for it if you want – A super smooth Automatic Car which is Fuel Efficient too

Dual Clutch Transmission (DCT) - A dual-clutch transmission, or DCT (sometimes referred to as a twin-clutch transmission or double-clutch transmission), is a modern type of semi-automatic transmission and electrohydraulic manual transmission. It uses two separate clutches for odd and even gear sets. It can fundamentally be described as two separate manual transmissions (with their respective clutches) contained within one housing, and working as one unit. They are usually operated in a fully automatic mode, and many also have the ability to allow the driver to manually shift gears in semi-automatic mode, albeit still using the transmission's electro-hydraulics. (Source – Wikipedia)

Pros – Super smooth / quick shifts; best performance; better FE
Cons – Extremely expensive than any AT options
Cars Today – VW Polo DSG; Skoda Rapid DSG; Ford Ecosport (2017), Figo

Go for it if you want – A super smooth Automatic Car which is Fuel Efficient and best performing too, but ready to make a big hole on pocket to buy it.

Automated Manual Transmission (AMT) – Also known as semi-automatic transmission (SAT) and several other names, this automatic transmission type utilizes a regular clutch and gear setup but automates the action by the use of sensors, actuators, processors, and pneumatics. The AMTs were born out of the need to make automatic cars affordable and fuel efficient. These are very simple and affordable. They’re also not very expensive to repair. Fuel efficiency is their top priority and it rivals that of manual transmissions. AMT is based on an electronic control unit and a hydraulic system that supervise the use of the clutch and the gear shifting, allowing the driver to change gear without using the clutch, either sequentially or fully automatically. (Source – Wikipedia)

In essence, it’s the same MT which is automated and controlled by a Computer than the driver.

Pros – Least expensive transmission; Ready units on offer to manufactures; best in FE
Cons – Jerky shifts – Head nod is inevitable but maybe less in Petrol engines or gentle driving;
Cars Today – Suzuki Vitara Brezza, Swift, Alto, Celerio; Tata Zest, Nexon, Tiago, Tigor; Mahindra TUV; Renault Kwid

Go for it if you want – The most fuel efficient AT Car but OK to compromise on the drive experience

Hope this thread will help you differentiate the AT options available on market today and start thinking which would work the best for you. Experts – Please feel free to correct or add anything further to make this thread more informative and useful [cheers]

adivik · Sep 18, 2018

Re: Automatic Transmission (AT) – TC / CVT / DCT / AMT: All You May Want To Know of A

I agree with most points except a couple

1) CVT sold today are CVT with Torque Convertor, so in City stop and go traffic conditions, even this combo will suffer from poor fuel efficiency for same reasons as TC with conventional gearbox.

2) DCT is even more fuel efficient than AMT but the biggest drawback is our stop and go conditions is the replacement of the clutches, while in AMT it is a simple job to replace the clutch every year or two in DCT it is an expensive affair.

Figoian · Sep 19, 2018