A planetary gear train of claim of an automatic transmission for a vehicle may include an input shaft for receiving an engine torque, an output shaft for outputting a shifted torque, a first planetary gear set, a second planetary gear set, a third planetary gear set, a fourth planetary gear set, a first shaft, a second shaft, a third shaft, a fourth shaft directly connected with a transmission housing, a fifth shaft selectively connectable with the second shaft, a sixth shaft directly connected with the output shaft, a seventh shaft, an eighth shaft selectively connectable with the first shaft and the second shaft, and directly connected with the input shaft, and a ninth shaft selectively connectable with the sixth shaft.

A planetary gear train of an automatic transmission for a vehicle may include an input shaft receiving torque of an engine, an output shaft outputting changed torque of the engine, a first planetary gear set including first, second, and third rotation elements, a second planetary gear set including fourth, fifth, and sixth rotation elements, a third planetary gear set including seventh, eighth, and ninth rotation elements, a fourth planetary gear set including tenth, eleventh, and twelfth rotation elements, and seven friction elements disposed between at least one rotation element among the twelve rotation elements and another rotation element or the input shaft, or between at least one rotation element among the twelve rotation elements and a transmission housing.

The present disclosure provides a planetary gear train of an automatic transmission for a vehicle. The planetary gear train may include: an input shaft receiving torque of an engine; an output shaft outputting changed torque; a first planetary gear set including first, second, and third rotation elements; a second planetary gear set including fourth, fifth, and sixth rotation elements; a third planetary gear set including seventh, eighth, and ninth rotation elements; a fourth planetary gear set including tenth, eleventh, and twelfth rotation elements. The planetary gear train improves power delivery performance and fuel economy by achieving at least eleven forward speed stages and widening speed ratio (or gear ratio) with a reduced number of constituent elements being used, and secures linearity of step ratios.

A transmission (G) is provided having four planetary gear sets (P1, P2, P3, P4), several shafts (W1-W8) and a first, second, third, fourth and fifth shift element (B1, B2, K1, K2, K3), the selective meshing of which brings about different transmission ratio relationships between a transmission input shaft (GW1) and a transmission output shaft (GW2). The transmission (G) includes a sixth shift element (K4), through which the fifth shaft (W5) is connectable to the sun gear (So-P4) of the fourth planetary gear set (P4).

A planetary gear train of an automatic transmission for vehicles may include an input shaft receiving power of an engine, an output shaft outputting shifted power of the engine, a first planetary gear set including first, second, and third rotating elements, a second planetary gear set including fourth, fifth, and sixth rotating elements, a third planetary gear set including seventh, eighth, and ninth rotating elements, a fourth planetary gear set including tenth, eleventh, and twelfth rotating elements, and seven control elements disposed between the rotating elements and at positions selectively connecting the rotating elements and a transmission housing.

A planetary gear train may include an input shaft, an output shaft, four planetary gear sets having first to twelfth rotation elements, a first shaft connected with the first rotation element and selectively connectable with a transmission housing, a second shaft interconnecting the second and fourth rotation elements, and connected with the input shaft, a third shaft interconnecting the third rotation element and the tenth rotation element, a fourth shaft connected with the fifth rotation element, a fifth shaft interconnecting the sixth and seventh rotation elements, and selectively connectable with the first shaft, a sixth shaft connected with the eighth rotation element and selectively connectable with the respective third and fourth shaft and selectively connectable with the transmission housing, a seventh shaft interconnecting the ninth and twelfth rotation elements, and selectively connectable with the transmission housing, and an eighth shaft connected with the eleventh rotation element and the output shaft.

A planetary gear train of an automatic transmission for a vehicle may include: an input shaft receiving torque of an engine; an output shaft outputting changed torque; a first planetary gear set including a first rotation element, a second rotation element, and a third rotation element; a second planetary gear set including a fourth rotation element, a fifth rotation element, and a sixth rotation element; a third planetary gear set including a seventh rotation element, an eighth rotation element, and a ninth rotation element; and a fourth planetary gear set including tenth, eleventh, and twelfth rotation elements.

A planetary gear train of an automatic transmission includes an input shaft, an output shaft, and first to fourth planetary gear sets respectively including first to third, fourth to sixth, seventh to ninth, and tenth to twelfth rotating elements, wherein the input shaft and the second rotating element, the output shaft and the eleventh rotating element, the first and sixth rotating elements, the first and eighth rotating elements, the seventh and eleventh rotating elements, and the ninth and tenth rotating elements are fixedly interconnected, and the output shaft is selectively connected with the third rotating element, and achieves ten forward speeds and one reverse speed by selectively operating three control elements among seven control elements.

A planetary gear train of an automatic transmission for a vehicle may include an input shaft from an engine, an output shaft, and first, second, third, and fourth planetary gear sets each including three rotation elements. The gear train also includes eight shafts for selectively connecting the planetary gear sets and the input and output shafts in various configurations to achieve at least ten forward speeds and at least four reverse speeds.

In an automatic transmission, the control part controls the engaging mechanisms and recognizes the rotational speed of a drive source and a stop request for the drive source. The automatic transmission changes the rotational speed of the input member to transmission gear ratios by the planetary gear mechanism and the engaging mechanisms so as to freely output the rotation from the output member. The engaging mechanisms include a switching mechanism switchable between a fixed state and a reverse rotation preventing state in which a normal rotation of a corresponding element among the elements of the planetary gear mechanism is allowed and a reverse rotation thereof is prevented. The control part switches the switching mechanism in a state in which the stop request for the drive source is not recognized and the rotational speed of the drive source is equal to or greater than a predetermined value.