US Patent 8083631 Planetary gear type gearbox

A planetary gear type gearbox includes a front-stage transmission section and rear-stage transmission section. The front-stage transmission section is for transmitting power from an input shaft to an intermediate shaft. The front-stage transmission section includes first, second and third clutches, two sets of planetary gear trains axially adjoining to each other. The first planetary gear train includes a sun gear, a carrier, a ring gear and planet gears. The second planetary gear train includes a sun gear, a carrier, a ring gear and two sets of planet gears. In the activation of second and third clutches, power is inputted into the carrier from the input shaft and is then outputted from the ring gear of the first planetary gear train.