Automatic transmission's ravigneaux type planetary gear train having two ring gears

Claim 1

A planetary gear system comprising: a stationary member, input means for receiving a driving torque, an output shaft, a compound planetary gear train comprising a plurality of pinion sets each comprising a first pinion and a second pinion meshing with each other, a pinion carrier supporting said first and second pinions, a first sun gear meshing with said first pinions, a first ring gear meshing with said first pinions and always connected with said output shaft, a second sun gear meshing with said second pinions, and a second ring gear meshing with said second pinions, a clutch group including a first clutch disposed between said input means and said first sun gear for connection and disconnection therebetween, a second clutch disposed between said input means and said second sun gear for connection and disconnection therebetween, and a third clutch disposed between said input means and said pinion carrier for connection and disconnection therebetween, and a holding device group including a first holding device disposed between said first sun gear and said stationary member for holding said first sun gear, a second holding device disposed between said pinion carrier and said stationary member for holding said pinion carrier, and a third holding device disposed between said second ring gear and said stationary member for holding said second ring gear, wherein each of said first pinions has a large gear section having a diameter and a small gear section which rotates with said large gear section as a unit and which has a diameter smaller than said diameter of said large gear section, said large gear section of each of said first pinions being in mesh with said first sun gear, and said small gear section of each of said first pinions being in mesh with said first ring gear, and wherein, in each pinion set, said second pinion is in mesh with said small gear section of said first pinion.