What type of gears are typically used in car transmissions for smooth shifting?

Planetary gears are typically used in car transmissions for smooth shifting due to their compact design and ability to provide multiple gear ratios within a small space. This system consists of a sun gear, planet gears, and a ring gear, allowing various combinations of gear engagement. The arrangement enables smooth transitions between gears, which is essential for maintaining a seamless driving experience. Additionally, planetary gears distribute the load across multiple gears, enhancing durability and performance under varying conditions. This efficiency in design is particularly valuable in automatic transmissions, where the system must quickly adjust to changes in speed and torque while providing a comfortable ride.