Planetary gear train of automatic transmission for vehicles

A planetary gear train of an automatic transmission for vehicles, comprising:

• an input shaft adapted to receive engine torque;
• an output gear adapted to output a shifted torque;
• a first compound planetary gear set having four rotation elements by combining first and second planetary gear sets and adapted to primarily shift torque input through two input paths into five speed ratios and to output the primarily shifted torque;
• a second compound planetary gear set having four rotation elements by combining third and fourth planetary gear sets and adapted to secondarily shift the torque input from the first compound planetary gear set and the torque input from the input shaft through one path into nine forward speeds and one reverse speed and to output nine forward speeds and one reverse speed;
• eight rotation shafts including two rotation elements connected to each other;
• and
• six friction members including three clutches coupled to the input shaft and adapted to selectively transmit the torque to selected ones of the rotational shafts, and including three brakes interposed between a selected rotational shaft among the rotational shafts and a transmission housing;
• wherein:
• a first forward speed is achieved by operating a first clutch, a second brake, and a third brake,
• a second forward speed is achieved by operating a second clutch, the second brake, and the third brake,
• a third forward speed is achieved by operating the first clutch, the second clutch, and the third brake,
• a fourth forward speed is achieved by operating the first clutch, a third clutch, and the third brake,
• a fifth forward speed is achieved by operating the first clutch, the second clutch, and the third clutch,
• a sixth forward speed is achieved by operating the second clutch, the third clutch, and the second brake,
• a seventh forward speed is achieved by operating the first clutch, the third clutch, and the second brake,
• an eighth forward speed is achieved by operating the third clutch, a first brake, and the second brake,
• a ninth forward speed is achieved by operating the first clutch, the third clutch, and the first brake, and
• a reverse speed is achieved by operating the first clutch, the first brake, and the third brake.

A planetary gear train of an automatic transmission for vehicles, comprising:

• an input shaft adapted to receive engine torque;
• an output gear adapted to output a shifted torque;
• a first compound planetary gear set having four rotation elements by combining first and second planetary gear sets and adapted to primarily shift torque input through two input paths into five speed ratios and to output the primarily shifted torque;
• a second compound planetary gear set having four rotation elements by combining third and fourth planetary rear sets and adapted to secondarily shift the torque input from the first compound planetary gear set and the torque input from the input shaft through one path into nine forward speeds and one reverse speed and to output nine forward speeds and one reverse speed;
• eight rotation shafts including two rotation elements connected to each other;
• and
• six friction members including three clutches coupled to the input shaft and adapted to selectively transmit the torque to selected ones of the rotational shafts, and including three brakes interposed between a selected rotational shaft among the rotational shafts and a transmission housing;
• wherein the first compound planetary gear set is a compound planetary gear set formed by combining the first planetary gear set being a double pinion planetary gear set and the second planetary gear set being a single pinion planetary gear set by sharing a ring gear and a planet carrier in common, and includes a first sun gear engaged with a short pinion, a second sun gear engaged with a long pinion, a common planet carrier, and a common ring gear, and
• wherein the first compound planetary gear set comprises:
• a first rotation shaft including the first sun gear and adapted to be selectively connected to the transmission housing;
• a second rotation shaft including the common ring gear;
• a third rotation shaft including the common planet carrier, and adapted to be selectively connected to the input shaft or to the transmission housing;
• a fourth rotation shaft including the second sun gear and adapted to be selectively connected to the input shaft;
• a first clutch interposed between the input shaft and the fourth rotation shaft;
• a second clutch interposed between the input shaft and the third rotation shaft;
• a first brake interposed between the third rotation shaft and the transmission housing;
• and
• a second brake interposed between the first rotation shaft and the transmission housing.

A planetary gear train of an automatic transmission for vehicles, comprising:

• an input shaft adapted to receive engine torque;
• an output gear adapted to output a shifted torque;
• a first compound planetary gear set formed by combining a first planetary gear set having a first sun gear, a first planet carrier, and a first ring gear as rotation elements thereof and a second planetary gear set having a second sun gear, a second planet carrier, and a second ring gear as rotation elements thereof;
• a second compound planetary gear set formed by combining a third planetary gear set having a third sun gear, a third planet carrier, and a third ring gear as rotation elements thereof and a fourth planetary gear set having a fourth sun gear, a fourth planet carrier, and a fourth ring gear as rotation elements thereof;
• a first rotation shaft including the first sun gear and adapted to be selectively connected to a transmission housing;
• a second rotation shaft including the first planet carrier and the second ring gear;
• a third rotation shaft including the first ring gear and the second planet carrier, and adapted to be selectively connected to the input shaft or to the transmission housing;
• a fourth rotation shaft including the second sun gear and adapted to be selectively connected to the input shaft;
• a fifth rotation shaft including the fourth sun gear and adapted to be directly connected to the second rotation shaft;
• a sixth rotation shaft including the third ring gear and the fourth planet carrier, and adapted to be selectively connected to the input shaft;
• a seventh rotation shaft including the third planet carrier and the fourth ring gear, and adapted to be directly connected to the output gear;
• an eighth rotation shaft including the third sun gear and adapted to be selectively connected to the transmission housing;
• and
• six friction members including three clutches interposed between a selected rotation shaft among the rotation shafts and the input shaft so as to selectively transmit torque of the input shaft and three brakes interposed between a selected rotation shaft among the rotation shafts and the transmission housing.

A planetary gear train of an automatic transmission for vehicles, comprising:

• an input shaft adapted to receive engine torque;
• an output gear adapted to output a shifted torque;
• a first compound planetary gear set including a first sun gear engaged with a short pinion, a second sun gear engaged with a long pinion, a common planet carrier, and a common ring gear;
• a second compound planetary gear set formed by combining a third planetary gear set having a third sun gear, a third planet carrier, and a third ring gear as rotation elements thereof and a fourth planetary gear set having a fourth sun gear, a fourth planet carrier, and a fourth ring gear as rotation elements thereof;
• a first rotation shaft including the first sun gear and adapted to be selectively connected to a transmission housing;
• a second rotation shaft including the common ring gear;
• a third rotation shaft including the common planet carrier, and adapted to be selectively connected to the input shaft or to the transmission housing;
• a fourth rotation shaft including the second sun gear and adapted to be selectively connected to the input shaft;
• a fifth rotation shaft including the third ring gear and adapted to be directly connected to the second rotation shaft;
• a sixth rotation shaft including the third planet carrier and the fourth ring gear, and adapted to be selectively connected to the input shaft;
• a seventh rotation shaft including the fourth planet carrier and adapted to be directly connected to the output gear;
• an eighth rotation shaft including the third sun gear and the fourth sun gear, and adapted to be selectively connected to the transmission housing;
• and
• six friction members including three clutches interposed between a selected rotation shaft among the rotation shafts and the input shaft so as to selectively transmit torque of the input shaft and three brakes interposed between a selected rotation shaft among the rotation shafts and the transmission housing.