If you’ve shopped for a new car in the last few years, you may have come across vehicles with continuously variable transmissions (CVTs). With a traditional transmission, a fixed number of gear ratios are available and the engine must perform a hard shift to move between them. With a manual transmission, the driver controls when these shifts occur. An automatic transmission will shift itself based on how the driver is pushing the engine.
The CVT is a completely different approach to the transmission because it eliminates the need to shift between gears. Instead, the CVT allows for a wide range of different gear ratios that change seamlessly while driving. Because of this, CVTs are also called stepless, shiftless, or single-speed transmissions.
In commercial vehicles, CVTs have only recently become popular, but the concept actually traces all the way back to Leonardo DaVinci. The first CVT patent was granted in 1886 to Daimler and Benz. In 1910, Zenit motorcycles introduced a CVT model that was banned from hill-climbing competitions because it was considered too efficient and gave riders an unfair advantage.
After that point, the design fell out of popular approaches to vehicle engineering until the late 1980s, when Subaru reintroduced the CVT. Since then, the technology has gained popularity. Nowadays, pretty much every major car manufacturer has at least one model with a CVT.
How the CVT Works in Most Modern Vehicles
The CVT is fundamentally different from traditional transmissions. Traditional designs used several intricate parts to shift between preset gears. Instead of gears, CVT systems generally use two pulleys connected by a belt. Each pulley consists of two cones that can move closer together or further apart. One pulley is connected to the engine, and another directs power to the wheels.
The pulleys can move to either increase or decrease the belt diameter, which changes the gear ratios and makes it easy to move into the ideal position for the current speed. The result is a smoother driving experience, as well as better fuel economy. The car can accelerate without any of the jerking motions associated with shifting gears.
Although the pulley system is most common, some other types of CVTs also exist. Another setup that you may see involves discs and rollers instead of conical pulleys, but the basic operation is exactly the same.
In addition, while the CVT does not involve actual gears, some manufacturers create preset positions for the pulleys so that they function more like a traditional transmission. The advantage of this approach is that the car can drive like a manual car with “shifting” facilitated by paddle shifters on the steering wheel or even a traditional shift level as part of the center console.
Why Manufacturers Make Vehicles with CVTs
Given that CVT technology dates back hundreds of years, you may wonder why it has only recently gained popularity. The answer is that most manufacturers are only now discovering how well they work for most customers. CVTs help people get more power out of small engines, which means that vehicles are more responsive with faster acceleration. In other words, the technology makes for a more enjoyable driving experience.
The average driver also benefits from the improved fuel economy of CVT. Most modern hybrids employ CVT systems because they are so fuel-efficient. Even fully gasoline-powered cars can benefit, however, with the average midsize sedan with a CVT getting close to 40 miles per gallon.
For the most part, CVTs make driving easier. Cars with CVTs accelerate much more smoothly. Passing other vehicles on the highway is also easier because no downshifting is necessary. (Downshifting can cause a delay in acceleration with automatic transmissions.) With a CVT, the power boost is instantaneous. Driving uphill is also easier with a CVT because traditional transmissions often struggle to find the right gear ratio. CVTs eliminate the guesswork and allow for seamless power without any hard shifts disrupting the ride.
The Downside to Purchasing a Vehicle with a CVT
If CVTs are so great, why don’t all vehicles use them? While the CVT has many pros, there are also cons to consider. The biggest issue is that CVT systems cost more than traditional transmissions. In addition, repair and replacement costs can be much higher. Typically, CVT systems do not last as long as traditional transmissions and can fail around 100,000 miles, while traditional setups can go for 200,000 miles and beyond. Replacing the system costs thousands of dollars. For many buyers, these costs are prohibitive.
The other cons related to the CVT have to do with performance. While the driving experience tends to be smoother with the CVT, these systems are not made for high-performance vehicles. You will not see CVTs in racecars or sports coupes because they only function in relatively low horsepower situations. If you are looking for a performance vehicle, stick with one with a traditional transmission. Part of the issue also relates to noise. Because CVT systems sound different from the traditional transmissions many people are used to, the experience can be off-putting for some drivers.