Patent ID: 8197379

Claim:
A transmission mechanism, comprising: a first gear unit including a first planet gear disk, a plurality of first planet gears, a ring gear having a plurality of first inner teeth, a second planet gear disk having a plurality of outer teeth, a plurality of second planet shafts, and a first pinion, and a plurality of second planet gears, the first planet gears being connected to the first planet gear disk, the first pinion being engaged with the first planet gears, the second planet gears being connected to the plurality of second planet shafts on the second planet gear disk, the ring gear being axially movable to engage the first inner teeth with the outer teeth of the second planet gear disk, or to disengage the first inner teeth from the outer teeth of the second planet gear disk, the first planet gear disk connected with an output shaft; and a second gear unit including a third planet gear disk having a plurality of second positioning ridges, a fixing ring having a plurality of first protrusions and a plurality of second protrusions, an inner gear having a plurality of first positioning ridges and a plurality of second inner teeth, and a plurality of third planet gears having a second pinion, the third planet gears connected to the third planet gear disk and the second pinions engaged with the second inner teeth of the inner gear, the third planet gears engaged with a motor gear, the fixing ring being axially movable to engage the first protrusions with the first positioning ridges, or to engage the second protrusions with the second positioning ridges; wherein when the ring gear is moved to engage the first inner teeth with the outer teeth of the second planet gear disk and the fixing ring is moved to engage the first protrusions with the first positioning ridges, an input speed from the motor gear is transferred into a first speed which is output from the output shaft; when the ring gear is moved to engage the first inner teeth with the outer teeth of the second planet gear disk and the fixing ring is moved to engage the second protrusions with the second positioning ridges, an input speed from the motor gear is transferred into a second speed which is output from the output shaft; when the ring gear is moved to disengage the first inner teeth from the outer teeth of the second planet gear disk and the fixing ring is moved to engage the first protrusions with the first positioning ridges, an input speed from the motor gear is transferred into a third speed which is output from the output shaft; and when the ring gear is moved to disengage the first inner teeth from the outer teeth of the second planet gear disk and when the fixing ring is moved to engage the second protrusions with the second positioning ridges, an input speed from the motor gear is transferred into a fourth speed which is output from the output shaft.