Did you know?
It was in 1958 that Van Doorne's Automobiel Fabriek introduced DAF 600, which was the very first car that came with a continuously variable transmission (CVT).
The transmission system of an automobile is an integral car part that turns engine rotations into torque, which in turn allows one to drive the car at variable speeds. The transmission systems are categorized into manual and automatic transmissions.
A continuously variable transmission (CVT) is a type of automatic car transmission system that uses a pulley and belt system to provide an unlimited range of gear ratios. In 1984, the Japanese automobile manufacturer, Subaru, introduced the electronic continuously variable transmission (ECVT) in a hatchback called Subaru Justy. It was sold between 1989 and 1993 in the United States. Though CVT equipped vehicles were not well-received in the automobile industry earlier, over the years, improved continuously variable transmission systems have been developed, and these are capable of handling more powerful engines. Several established automakers such as Audi, Nissan, Ford, and Honda have incorporated advanced versions of CVT in their automobiles. However, it must be noted that despite offering certain advantages such as improved gas mileage and fuel efficiency, a CVT doesn't offer the driving feel associated with cars with conventional automatic or manual transmission systems. When it comes to acceptance, cars equipped with a continuously variable transmission have a long way to go. Some of the models have failed, which often raises doubts in the minds of prospective buyers.
How Does a Continuously Variable Transmission Work
Cars with a CVT system make use of a pair of variable-diameter pulleys and belts to provide varied gear ratios. The input pulley is connected to the engine, whereas the output pulley is connected to the drive wheels. A metal belt runs between the two pulleys. When the pulley halves come closer to each other, the metal belt or chain goes higher on the pulley, thereby increasing the diameter of the pulley. Different gear ratios are achieved through the change in the diameter of the pulleys. Lower ratio would be achieved when the diameter of the input pulley is smaller than the output pulley and vice versa. Thus, the change in the diameter of pulleys plays a great role in changing the ratio of engine speed to car speed. Automakers have also come up with other types of continuously variable transmissions such as hydrostatic or toroidal CVT. Toroidal CVT systems use power rollers and discs, whereas hydrostatic systems use hydrostatic pumps and motors for getting varied gear ratios. Some cars come with an electrically-controlled CVT. However, these should not be confused with CVT, as this system requires a single planetary gearset (Power Split Device) in place of regular-CVT friction belts. Unlike a CVT that provides infinite gear ratios, an ECVT provides a fixed gear ratio.
CVT vs Manual & Conventional Automatic Transmission
Though cars with CVT may provide superior fuel economy and better acceleration, automobile enthusiasts often raise the issue of reliability. Some of the car models that were equipped with CVT, have received bad reviews. For instance, safety concerns were raised over the CVT-equipped Ford Freestyle, due to the sudden, unexpected breakdowns while driving. Some of CVT-equipped models by Nissan have also been criticized.
Moreover, people are bound to compare CVT with its manual and conventional automatic counterpart. The major drawbacks of the CVT are associated with the driving feel. Most car enthusiasts feel that there's a great deal of difference in the driving feel associated with an automatic transmission. For some, it is the lack of sense of control that one feels while driving a car with a manual transmission. Let's find out what differentiates CVT from the manual and conventional automatic transmission systems.
Besides being less expensive, manual transmissions give the person driving the vehicle a feeling of complete control. When you are driving a vehicle with a manual transmission, you have to operate the clutch and shift gears to get the ratio required for driving the vehicle in a particular situation. While you use the lowest gear for starting up, you need to shift to higher gear for fuel-efficient driving. The gears basically help to use the torque effectively, and keep the car's engine running at the right speed.
Cars with an automatic transmission come with a gearbox that can change gear ratios automatically as the vehicle moves. The speed and the engine load is measured by the computerized system. There is a predefined set of gear speeds, and the needed gear shifts are automatically made, as and when the system delivers an electronic signal. You can also opt for cars with a dual-clutch transmission. The dual-clutch transmission, as the name suggests, comes with two clutches, and doesn't have a pedal to control them. This makes the gear change faster as the next gear is pre-selected by the clutch depending on your speed and throttle position.
Problems Associated with a CVT
While improved acceleration and enhanced fuel economy are believed to be its strong points, some people have voiced their concern regarding CVT reliability. The fact that the CVT system is more expensive may affect the user acceptance in an adverse manner. Car owners who have earlier driven cars with a manual or an automatic transmission might find it difficult to adjust if they switch to a car with a CVT system.
- Cars with CVT do produce some noise on initial startup, and also when you try to accelerate. The car noise is produced as a result of CVT trying to adjust the engine speed.
- Though CVT mechanism allows the engine to rev at any speed, there have been complaints about noises from the engine, which are often compared to the sound of the slipping clutch that is heard in a manual transmission. Those who are accustomed to driving cars with automatic transmission might find that slightly bothersome.
- While a CVT system is supposed to provide a smooth transition while accessing maximum power, there have been complaints about jerky movement during initial acceleration or rattling noises during slow speeds. Some people have also complained about abrupt movement while coming to a stop.
- Unlike the conventional automatic transmissions where you feel a change in the engine speed while shifting gears, people who drive cars with CVT system don't feel such gear shifts. Due to this, paddle shifts have been incorporated in vehicles with CVT to simulate gear changes.
Our Verdict :
CVT reviews have been somewhat mixed, and long-term reliability is still an aspect that needs to be looked into. Most of car enthusiasts don't like it. As CVT system is very different from conventional transmission, the decision to purchase a CVT must be made only after doing thorough research. Go for a test drive to check whether you are comfortable driving a car with CVT. Take drives of different cars. After all, an automobile is a major investment, and you shouldn't take a hasty decision.