Patent ID: 6547688
Filing Date: 2003-04-15
Classification: F16H

Abstract:
An automatic transmission for a vehicle, comprising:an input shaft connected to an output shaft of an engine; an output shaft connected to an axle shaft via a differential gear; a torque converter for transmitting driving torque from the engine to the automatic transmission; a planetary gear system comprising first, second, third and fourth planetary gear sets, the first gear set having a first sun gear, a first ring gear, a pair of first pinion gears meshing with the first sun gear and the first ring gear, and a first planetary carrier rotatably supporting the first pinion gears, the first sun gear being connected to the input shaft, the second, third and fourth gear sets respectively having second, third and fourth sun gears, second, third and fourth ring gears, second, third and fourth single pinion gears meshing with each sun gear and ring gear, and second, third and fourth planetary carriers rotatably supporting the second, third, and fourth pinion gears; a first rotational element rotatably connecting the first and second ring gears and the third sun gear; a second rotational element rotatably connecting the second, third and fourth planetary carriers; a third rotational element rotatably connecting the third ring gear, the fourth sun gear, and the output shaft; a fourth rotational element rotatably connecting the second sun gear and the input shaft; a first clutch selectively connecting and releasing the second ring gear and the third sun gear; a second clutch selectively connecting and releasing the second rotational element and the input shaft; a first brake selectively holding the first rotational element against rotation and releasing the first rotational element; a second brake selectively holding the fourth ring gear against rotation and releasing the fourth ring gear; and a third brake selectively holding the first planetary carrier against rotation and releasing the first planetary carrier.