Patent ID: 9670992
Date: 2017-06-06
CPC Classifications: F16H

Claim:
1. A planetary gear train of an automatic transmission for a vehicle, comprising: an input shaft receiving torque of an engine; an output shaft outputting changed torque of the engine; a first planetary gear set including a first sun gear, a first planet carrier, and a first ring gear; a second planetary gear set including a second sun gear, a second planet carrier, and a second ring gear; a third planetary gear set including a third sun gear, a third planet carrier, and a third ring gear; a fourth planetary gear set including a fourth sun gear, a fourth planet carrier, and a fourth ring gear; a first rotation shaft including the first and second sun gears and selectively connected to a transmission housing; a second rotation shaft including the first planet carrier; a third rotation shaft including the first and fourth ring gears and selectively connected to the transmission housing; a fourth rotation shaft including the second planet carrier and directly connected to the input shaft; a fifth rotation shaft including the second ring gear and the third and fourth sun gears; a sixth rotation shaft including the third planet carrier and selectively connected to the second and fourth rotation shafts; a seventh rotation shaft including the third ring gear and selectively connected the second rotation shaft; an eighth rotation shaft including the fourth planet carrier and selectively connected to the seventh rotation shaft, and directly connected to the output shaft; and six friction elements, wherein each of the six friction elements are disposed to selectively connect at least one of the first to eighth rotation shafts with another rotation shaft of the first to eighth rotation shafts or the transmission housing, wherein the six friction elements comprise: