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Understanding Automatic Gearbox in Cars - Which One Should You Buy? CVT, DCT, iMT and More

By: Anirudh SK

News18.com

Last Updated: May 20, 2021, 14:37 IST

Kia Seltos. (Photo: Arjit Garg/News18.com)

Kia Seltos. (Photo: Arjit Garg/News18.com)

With so many options of automatic transmission in India, there is no need to run amok. We have prepared a complete breakdown of the types and working of the options that will suit you best.

Delicately put, India is a price sensitive market. We are obsesses with getting the best value for money when it comes to automobiles. As the demand calls for it, automakers often find a way to cut corners and make the product as appealing as possible. This is one of the reasons why you don’t see premium and high-end features like a panoramic sunroof or cruise control in most vehicles. Not surprisingly even basic features like auto ORVMs and auto air conditioning are reserved for the top-rung variants. One such feature, in the mechanical department, would be automatic transmission or two-pedal technology. Now, it should be noted that most countries past our shores have an auto transmission as standard. However, Indians have always relied on manuals. Yes they provide better fuel efficiency, yes they are more fun to drive. But picture yourself in a city with excruciating traffic and the manual becomes another nail in the coffin. Tapping this very demand, automakers are now coming up with new and innovative solutions that would cater to a range of people from cost-conscious buyers to enthusiasts. With so many options out there we thought a video that decodes these technologies was called for. Hence, let’s take a closer look at each one of it.

Watch Video:

1) Automatic Transmission

The torque converter automatic transmission is by far the most common one on the road today. It uses a highly-complex torque converter to transmit the engine’s rotational energy, while gear shifts are controlled by the vehicle’s computer and accomplished with a planetary gear set and a series of clutches and brakes.

Though the behind-the-scenes action is quite complicated, all the driver has to do is select from the familiar P-R-N-D-L choices on the gear selector. The advantage is, of course, a simplified driving experience and a gentle learning curve. The trade-off for the driving simplicity is mechanical complexity, which makes the automatic more prone to failure and pricier to fix.

Torque-converter automatics are advantageous of big torque at low revs, which is great for acceleration off the line and overtaking. Acceleration from a standing start is smooth, as are the gear changes however, one traditional problem with torque converters is that they are essentially inefficient which usually means larger than usual fuel bills.

A few cars that have the torque converter include Ford EcoSport, Mahindra Thar, Tata Safari and Kia Seltos among others.

2) Continuously Variable Transmission (CVT)

The CVT offers a similar driving experience to an automatic, but operates using a completely different mechanism. In fact, the CVT doesn’t have gears at all — instead, it uses a system of belts and pulleys to produce an infinite range of ratios. The car’s computer decides how to adjust the pulleys to create the optimal ratio for the particular driving situation. This creates the CVT’s primary advantage: fuel economy. No other transmission type can offer more MPGs than a CVT (yet).

Since they’re not as complicated as automatics, CVTs are less prone to failure and costly repairs (though not as much so as manuals). Their biggest drawback may be a subjective one — the driving experience. Since there are no gearshifts, just smooth and seamless acceleration, CVTs may leave a true driving enthusiast feeling like he or she is operating an appliance instead of driving a car.

Cars that feature the CVT include the Hyundai Creta, Hyundai Verna, Honda Jazz, Nissan Magnite.

3) Dual-Clutch Transmission (DCT)

Think of it as a hybrid between a fully automatic and manual transmission. A semi-automatic uses a similar mechanical layout to a conventional transmission, but uses a system of pneumatics and actuators to change gears. In a Dual-Clutch Transmission (DCT), there are separate clutches for both odd and even gears, which allows for incredibly fast shifts. These gearboxes can generally be operated in a fully automatic mode, or manually shifted via paddles on the steering wheel.

Semi-Auto and DCT transmissions offer cutting-edge performance with lightening fast gear changes that a pure manual just can’t match. Currently, these gearboxes are mainly found on race and high-end sports cars, and are, therefore, quite expensive. This disadvantage is magnified by their extreme complexity, which leads to more frequent and costly repairs

You can get a DCT in cars such as the Hyundai i20, Kia Sonet and Volkswagen Tiguan All-Space among others.

4) Automated Manual Transmission (AMT)

Automated Manual Transmission or AMT, is also known as Semi-Automatic Transmission (SAT) or Clutchless Manual Transmission (CMT). As the name suggests, an AMT’s prime function is to automate manual transmissions, which means the job of pressing the clutch and shifting gears via a stick no longer rests with the driver. There are two types of AMT – single-clutch and dual-clutch.

AMT or Automated Manual Transmission is mechanically similar to a manual transmission, except that the sensors and actuators perform the clutch work and shift gears. A car with an AMT does not have a clutch pedal; there’s only the accelerator and brake pedal. AMT also allows manual gearshifts, when needed, by pushing forward the gear lever for upshift and pulling it backward for downshift.

Cars like the Grand i10 Nios, Tata Tiago, Mahindra XUV300, Hyundai Aura all have the Automated Manual Transmission.

5) Intelligent Manual Transmission (iMT)

Now the iMT might faintly whisper sacrilege in this list as it is not entirely automatic if you see. This type of transmission comes without a clutch but the traditional manual gear stick. Hyundai’s iMT is a hydraulically operated system. There are three main units to this system, a traditional gear shifter but with an intention sensor built-in, a hydraulic actuator and a transmission control unit. When you decide to change gears, the control unit is notified of this by the intention sensor. The control unit then uses the hydraulic actuator to create pressure. This pressure is used to control the clutch and pressure plate via a hydraulic mechanism, allowing the clutch to be engaged and disengaged without manual operation.

Since Hyundai debuted the transmission in the Venue it can also be found in cars including the Kia Sonet, Creta and Kia Seltos.

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first published:May 20, 2021, 14:37 IST
last updated:May 20, 2021, 14:37 IST