Patent ID: 9518637
Filing Date: 2016-12-13
CPC Classification: F16H

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