PLANETARY GEAR TRAIN OF AUTOMATIC TRANSMISSION FOR VEHICLES

摘要

Disclosed is a planetary gear train of an automatic transmission for a vehicle. According to an embodiment of the present invention, the planetary gear train of an automatic transmission for a vehicle of the present invention comprises: an input shaft for receiving the power of the engine; a first planetary gear set which has a first sun gear, a second planetary carrier, and a first ring gear; a second planetary gear set which has a second sun gear, a second planetary carrier, and a second ring gear; a third planetary gear set which has a third sun gear, a third planetary carrier, and a third ring gear; a fourth planetary gear set which has a fourth sun gear, a fourth planetary carrier, and a fourth ring gear; a first rotary shaft which comprises the second sun gear and is directly connected to the input shaft; a second rotary shaft which comprises the second planetary carrier; a third rotary shaft which comprises the first planetary carrier and the second ring gear and is selectively connected to the transmission housing; a fourth rotary shaft which comprises the first sun gear and is selected connected to the transmission housing or the second rotary shaft; a fifth rotary shaft which comprises the first ring gear and the third ring gear and is selectively connected to the second rotary shaft; a sixth rotary shaft which comprises the third planetary carrier and the fourth ring gear and is selectively connected to the input shaft; a seventh rotary shaft which comprises the fourth planetary carrier and is directly connected to the output shaft; an eighth rotary shaft which comprises the third sun gear and the fourth sun gear and is selectively connected to the input shaft; and six friction elements for selectively connecting the rotary shaft to the rotary shaft and the rotary shaft to the transmission housing.