Patent ID: 6955627

Claim:
A multiple-speed ratio automatic transmission for an automotive vehicle, comprising: an input shaft; output shaft; a planetary gear system comprising first, second, third, and fourth planetary gear units, each gear unit having a sun gear, a ring gear, planet pinions meshing with the sun gear and ring gear, and a carrier rotatably supporting the planet pinions; the input shaft being driveably connected to the sun gear of the first gear unit, the output shaft being driveably connected to the carrier of the third gear unit, the sun gear of the third gear unit and the sun gear of the fourth gear unit being mutually driveably connected, the carrier of the first gear unit and ring gear of the second gear unit being mutually driveably connected, the carrier of the second gear unit and ring gear of the fourth gear unit being mutually driveably connected, the ring gear of the third gear unit and carrier of the fourth gear unit being mutually driveably connected; a coupler for alternately holding against rotation and releasing the carrier of the fourth gear unit and the sun gear of the fourth gear unit; a first brake for holding against rotation and releasing the sun gear of the second gear unit; a first clutch for driveably connecting and disconnecting the ring gear of the first gear unit and carrier of the second gear unit; a second clutch for driveably connecting and disconnecting the ring gear of the first gear unit and input shaft; a third clutch for driveably connecting and disconnecting the sun gear of the fourth gear unit and the coupler; and a fourth clutch for driveably connecting and disconnecting the sun gear of the first gear unit and ring gear of the third gear unit.