Specialized instructional tool designed to illustrate the operation of planetary gear systems used in automatic transmissions. Featuring a detailed model with spur-type and bevel-type wheels on movable axes, this trainer allows users to explore the interaction between the planetary gear, crown gear, and planet gears. It demonstrates key principles such as rotational and revolution motion, showcasing how these components contribute to the functionality of differential systems and gear shifting mechanisms. This compact trainer provides an essential hands-on learning experience for understanding the dynamics of automatic transmission gear sets.