CVT transmission cars in India: What is it & how it works?

What is CVT in cars?

A CVT or Continuously Variable Transmission is a type of automatic transmission used in cars. Unlike other gearboxes, CVT transmission in cars can effortlessly variate between a limitless range of gear ratios while driving. Thus, you get more seamless gear shifts rather than a limited number of hard gear shift options like in other automatic transmissions. 

In a nutshell, a CVT comes with an infinite number of gear ratios with continuous on-the-go shifts to deliver a convenient driving experience. This gearbox system is also called a shiftless, step-less or single-speed transmission. Being step-less, this automatic gearbox provides constant and smoother acceleration, increasing the fuel economy of the vehicle over an Automatic Manual Transmission (AMT).

CVT transmission cars in India, 2022

Here are some of the CVT transmission cars in India as of June 2022.

How does CVT work?

A CVT works using a pulley system that involves a wide range of parts to smoothly shift between preset gears. Here are the key functions involved in the workings of CVT.

• Each pulley in the system remains connected to cones through chain belts. 

• The cones move freely to change the diameter of the belt to decrease or increase the gear ratios. 

• These quick shifts help to achieve the required gear ratios instantly.

• One of the pulleys remains connected to the engine, while others help to direct the mechanical energy to the wheels. 

• The pulleys change their width based on the required energy, resulting in seamless and strong acceleration. 

Generally, a CVT doesn’t come with a fixed number of gears, but some are designed with presets to make gear shifts easy to understand for drivers. 

Components of CVT transmission

A CVT car transmission consists of four main components.

1. Clutches

There are two types of clutches used in this gearbox.

Primary clutch: Typically installed at the engine crankshaft's output end, this is an advanced centrifugal clutch. It contains one stationary and one moveable sheave. The belt remains free from the sheave faces, which allows the engine to remain idle on neutral without sending any power to the wheels. 

Secondary clutch: The secondary clutch remains installed to the transmission’s input shaft. The role of this clutch is to work as a torque-sensing component in modern CVT gearboxes. 

2. Pulleys

The conical-shaped pulleys are used to continuously variate between gear and speed ratios. Both output and input shafts consist of a pair of pulleys of the following types.

Input pulley (fixed): This pulley gets mounted on the right side of the input shaft and moves only with the shaft rather than moving freely (to and fro).

Output pulley (fixed): This pulley is similar to the fixed input one but mounted on the left side of the output shaft. 

Input pulley (feeding): Installed on the input shaft, this pulley can not only rotate with the shaft but move back and forth over the shaft as well. This way, it allows a shift of gear ratios in the transmission. 

Output pulley (feeding): Similar to the input feeding pulley, the output feeding pulley remains on the output shaft to move back and forth and adjust the gear ratios. 

3. Shafts

Shafts are required to transfer the energy generated from the car’s engine to the gearbox. There are two shafts present in a CVT transmission. 

Input shaft: The cross-section of the input shaft contains splines to mount the input pulleys. The transmission system gets its power straight from the engine via the input shaft. 

Output shaft: The output shaft remains in a parallel position to the input shaft in CVT and its cross-section also contains splines to mount the output pulleys. This shaft directs the energy obtained from the engine to the wheels.

4. Chain or belt

A CVT contains a sturdy V-shaped belt made of reinforced rubber. The role of this belt or chain is to direct the energy from each input pulley towards the output pulley. 

Different types of CVT

There are three major types of CVT gearboxes as mentioned below.

1. Pulley-based CVT

The pulley-based CVT contains lesser parts than other automatic and manual transmissions, giving it a much simpler design. The parts of this type of CVT include an output pulley, an input pulley with variable diameter, a V-shaped belt and a couple of electronic devices. The distance between the two pulleys is changed through variable diameter to achieve different gear ratios. 

2. Toroidal CVT

The toroidal CVT is slightly different from a pulley-based CVT. The design contains a pair of discs and rollers, instead of belts and pulleys. Two rollers in the middle of two discs manage torque distribution to enable an infinite number of gear ratios.

3. Hydrostatic CVT

The hydrostatic CVT system consists of hydrostatic motors and pumps. The fluid displacement enables torque distribution, allowing a range of continuous gear ratios to select from. This kind of CVT lowers the friction-related issues by replacing certain parts with hydraulics. 

CVT vs AMT vs Manual: What’s the difference?

The CVT transmission differs from an Automatic Manual Transmission (AMT) and manual transmission in the following ways.

Advantages of CVT

Here are the major advantages of driving a CVT-enabled car.

• Better consumption of fuel than other automatic transmissions to deliver optimum power to the vehicle. 

• Reduced loss of power resulting in better acceleration in start-and-stop traffic.

• Offers a smoother driving experience than AMT.

• In the Hydrostatic CVT, a hydraulic motor is installed on the wheel hub, which eliminates the loss of efficiency due to driveshaft-related friction. 

• Easily adapts to changing power demands based on the road and traffic conditions.

• Better control over the emissions due to the improved range of engine speed.

Disadvantages of CVT

Here are certain disadvantages that come along with CVT transmission.

• It may take a while to adjust to the different feel of driving a car with CVT over AMT or manual.

• The cost of buying a CVT car is marginally higher than an AMT or manual car.

• Motion transmission using belts and pulleys increases friction-related wear.

• The system requires special lubrication and other maintenance checkups. 

How to maintain a CVT transmission

You can maintain a CVT transmission by following these simple preventive measures.

• Replace and top-up the engine oil at regular intervals.

• Change the oil and air filters from time to time to maintain performance.

• Keep an eye on tyre pressure and tyres’ tread depth to avoid added pressure on the transmission.

• Get the wheel alignment checked for a smoother driving experience.

How to efficiently drive a CVT car

You can drive CVT transmission cars more efficiently by following these tips.

1. Get acquainted with the CVT transmission

Understand the workings of CVT by spending time behind the wheels. Get a feel of how the engine performs at different shift patterns and RPMs. It will help you to become efficient in driving a CVT car. 

2. Don’t rest your foot on the brake pedal

The absence of a clutch pedal in automatic cars means that you don’t need to frequently use your left leg while driving. However, some drivers, who haven’t gotten used to driving an automatic car, subconsciously put their leg on the brake pedal. This increases the brake wear and puts more pressure on the engine, resulting in lower fuel efficiency. 

3. Apply steady inputs to the throttle

Your throttle input must be linear to avoid engine strain and maximise fuel efficiency. Irregularity in throttle input results in sudden acceleration and deceleration. This hampers engine performance and increases the to-and-fro movement of the vehicle body. Thus, you must be gentle when applying throttle inputs. 

4. Refrain from aggressive driving

Constant aggressive driving will get the CVT transmission into overdrive. It may result in a lag between the engine making a revving sound and gearbox upshift. Also, aggressive driving will reduce the fuel efficiency of your vehicle. So, it makes more sense to drive a CVT car at a moderate speed.

5. Plan ahead for your overtakes

A CVT gearbox reacts to throttle inputs faster than AMTs. A well-designed CVT can be as quick as some Dual-clutch Transmissions (DCTs). Hence, you must plan before overtaking by bringing the engine to the correct RPM level. Otherwise, the transmission system will have to variate the gear ratios to send the required kinetic energy to the wheels. This can cause the engine to use more than the required fuel. 

6. Shift to neutral when possible

Whenever stranded at traffic signals, you should consider shifting the gearbox to neutral. Keeping the transmission in the drive mode while standstill will increase the consumption of fuel. Moreover, it will put additional pressure on the braking system. Thus, it would be better to shift to neutral and use the handbrake whenever possible. 

Also, read: How to drive a car? Automatic and manual car driving tips

Are CVT transmission cars reliable?

Cars with Continuously Variable Transmission are typically designed to improve fuel economy and offer better dependability than the AMT gearbox. It would be a perfect choice if you want to experience smooth driving in a stop-and-go traffic situation. However, if you want a performance-driven car or if you are looking for the traditional gearbox feel of driving, then a CVT won’t be the right choice. 

Frequently asked questions

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