What is the difference between CVT and AT transmissions?
2 Answers
AT and CVT transmissions differ in the following aspects: Principle: The AT operates by using a torque converter whose automatic speed and torque variation range is insufficient, hence several rows of planetary gears are connected in series behind the turbine to enhance efficiency. The hydraulic control system automatically operates the planetary gears in response to changes in engine operation, thereby achieving automatic speed and torque variation. The CVT's drive pulley has a unique structure, divided into movable left and right halves that can move closer together or apart. The conical discs can tighten or expand under hydraulic thrust, squeezing the steel belt to adjust the width of the V-shaped groove. When the conical discs move inward and tighten, the steel belt is pushed outward from the center, and vice versa. This changes the diameter of the disc driven by the steel belt, altering the gear ratio. Usage: The AT does not require a clutch for shifting, has fewer gear changes with significant variation, and provides smooth engagement, making it easy to operate. It offers convenience for the driver and comfort for passengers. The CVT lacks the transmission gears found in conventional automatic transmissions, eliminating the gear-shifting process and the associated jerky sensation. As a result, the CVT delivers linear power output, ensuring a very smooth driving experience in practice.
The biggest difference between CVT and AT transmissions lies in their shifting methods. Having driven many cars, I can say CVTs don't have fixed gears - they use conical pulleys and steel belts for speed variation, delivering seamless acceleration without any jerking, making them ideal for city traffic with relaxed, comfortable driving. ATs feature multiple fixed gears shifted via planetary gear sets, where you can feel slight 'clicks' or jerks during gear changes, which actually feels exciting during highway overtaking. From a fuel efficiency perspective, CVTs maintain optimal engine RPM, theoretically offering better mileage - my experience with Nissan's CVT models showed significantly lower fuel consumption. While modern ATs are also efficient, their complex structures pose higher maintenance risks, like torque converter wear. Overall, CVTs deliver quieter, smoother daily driving, whereas ATs respond faster for speed enthusiasts. Beginners may prefer CVT's foolproof operation, while experienced drivers often favor AT's handling feel. Both have merits - the choice depends on your driving preferences.
