The principle of nylon gear transmission is very simple. Among a pair of intermeshing gears, there is a gear as the driving wheel, and the power is transmitted from it. The other gear is the driven wheel, and the power is output from it. Some gears only serve as a transfer station. One side meshes with the driving wheel and the other side meshes with the driven wheel, and the power passes through it. In a gear system that includes planetary gears, the situation is different. Due to the existence of a planet carrier, that is, there can be three rotating shafts to allow power input/output, a means such as a clutch or a brake can also be used to restrict the rotation of one of the shafts when needed, leaving the remaining two shafts to transmit. In this way, the relationship between intermeshing gears can be a combination of: the power input from one of the sun gears, the output from the other sun gear, the planet carrier braked by the brake mechanism, and the power input from one of the sun gears, From the planet carrier output, another sun wheel is braked; power is input from the planet carrier, and output from one of the sun gears; the other sun wheel is braked; two powers are input from the two sun gears respectively, and are synthesized and output from the planet carrier; The two powers are respectively input from the planet carrier and one of the sun gears, and are synthesized and output from another sun gear; the power is input from one of the sun gears, and the other sun gear and the planet carrier are output in two ways; the power is input from the planet carrier, Divided two ways from the two sun gears.