How Does a Continuously Variable Transmission Work?
4 Answers
The following is the working principle of a continuously variable transmission: 1. The power output from the engine's output shaft is first transmitted to the driving pulley of the CVT, then to the driven pulley via a V-shaped belt, and finally to the wheels through the reducer and differential to drive the car; 2. During operation, the movable discs of the driving and driven pulleys move axially to change the working radius where the conical surfaces of the driving and driven pulleys engage with the V-shaped belt. The axial movement of the movable discs is controlled by the driver through the system, which adjusts the pressure in the hydraulic pump cylinders of the driving and driven pulleys as needed; 3. Since the working radii of the driving and driven pulleys can be continuously adjusted, this enables continuous variable transmission.
The continuously variable transmission, also known as CVT, is one of the automotive technologies I've been researching. It uses a clever pulley system to replace traditional gear structures: a driving pulley and a driven pulley are connected by a sturdy steel belt or chain. When you accelerate, the width of the pulleys is automatically adjusted via hydraulic or electronic control, changing the position of the belt and the equivalent diameter of the pulleys, thereby continuously altering the gear ratio. This allows the engine speed to remain stable in the efficient range, unlike the stepped shifts in manual or automatic transmissions. The shifting process is seamless and smooth, reducing energy loss and improving fuel efficiency by approximately 20%. This design is more common in hybrid vehicles, such as Toyota models, which combine the engine and electric motor to achieve ultra-low emissions. However, the pulleys and steel belt require high-strength materials, and prolonged use may lead to noise or failures due to high-temperature wear. Regular inspection and maintenance are recommended to ensure the system operates reliably.
I've driven a car with a continuously variable transmission (CVT) for several years, and it's very simple to operate. At its core are two conical pulleys and a belt. When the engine runs, the width of the pulleys changes, allowing the belt to slide to different positions, much like adjusting the slope on a slide, continuously altering the speed output. This makes acceleration exceptionally smooth, without the jerky feeling of traditional gear shifts, which is especially comfortable in city traffic jams. Moreover, the engine always stays at its optimal RPM, significantly improving fuel efficiency—I save money every time I fill up. However, as an owner, I recommend paying attention to belt wear, especially after tens of thousands of miles, as an aging belt can lead to sluggish acceleration or unusual noises. Regular maintenance, such as changing the dedicated fluid, can extend the CVT's lifespan. Overall, this system noticeably enhances the driving experience and is particularly well-suited for daily commuting.
I just got my driver's license and am very interested in how CVT works. My instructor told me it uses two pulleys and a belt, with no fixed gears. When you press the accelerator, the distance between the pulleys automatically increases or decreases, and the belt moves to adjust the power transmission ratio, resulting in continuous speed changes. This makes driving super smooth, and beginners don't have to worry about shifting mistakes—acceleration feels very natural. I think it's similar to bicycle gear shifting, easy to get the hang of, and also fuel-efficient. Many small cars now use this design.
