Principle of gear shuttle:

Chemical energy in the battery is converted into kinetic energy of the motor. The motor drives the driving gear to rotate. When the driving gear touches the ground, the car moves forward along with the driving gear. When the driven gear touches the ground and meshes with the driving gear, the driven gear will follow the rotation and rotate in the opposite direction to the driving gear, thus realizing the reverse movement of the car. Therefore, it is called gear shuttle.