Patent attributes
A transmission mechanism includes a first gear unit having an axially-movable ring gear and a second gear unit having an axially-movable fixing ring. The fixing ring includes first and second protrusions on two sides, respectively. When the ring gear moves, the first inner teeth and the outer teeth of the second planet gear disk are engaged with each other or disengaged from each other. When the fixing ring moves, the first protrusions and the first positioning ridges are engaged with each other or disengaged from each other, or the second protrusions and the second positioning ridges are engaged with each other or disengaged from each other. By the different combinations of the statuses due to movement of the ring gear and the fixing ring, the input speed from the motor gear is transferred into four different speeds which is output from an output shaft.
