The "shaft" connected to the rear tires of the pull-back car is fixedly connected with the gear in the pull-back gear. When the hand works backwards (towing) the car, the rear wheel rotates backwards, and the force is transmitted to the pull-back gear through the shaft to do work, and the gear drives the return-to-power gear structure . The "shaft" connected to the rear tires of the pull-back car is fixedly connected with the gear in the pull-back gear. When the hand does work (drag) on the car backward, the rear wheel rotates backwards, and the force is transmitted through the shaft to the pull-back gear to do work, and the gear drives the return gear. The structure (spring structure or rubber band structure) converts the kinetic energy of the hand into potential energy (such as rubber band rotation extension or spring compression, etc.). The range of activities for children aged 7-12 months has been expanded, and there is already a basic His ability to act, he learns to sit, learn to crawl, and even begins to learn to walk. He has gone from making simple monophonic sounds to speaking consciously. He likes to beat and beat, and he also likes to put all kinds of things in his mouth to test the feeling of objects. When designing and developing wooden toys for children of this age, it is necessary to choose toys that can exercise his mobility, which will help him take the first step in life. But pay attention to choosing larger toys to prevent children from swallowing toys or toy parts in their mouths. For example, xylophones, walkers and other products are the preferred targets for designing toys for this age group.

When the hand is released, the car loses a force that maintains its balance, that is, the increased friction between the rear tire and the ground when the car is pressed by hand (that is, the grip force in F1), and the return gear is In the opposite direction, the shaft releases potential energy to do work, so the shaft rotates to convert the potential energy into kinetic energy. Since usually the back-wheeled car is designed to drive forward with the rear wheels (that is, the wheel is counterclockwise when viewed on the left of the car), the return-to-power gear is designed as a rear dump energy storage (that is, when the wheel is viewed clockwise on the left of the car), and because the usual axle Therefore, as long as the return gear can be stored large (that is, the number of revolutions is enough) or the static friction with the ground is small enough, the return gear can move forward through the energy output of the heart of the return gear.