An automatic transmission has a first clutch shaft that constantly connects first and fourth planetary gear sets, a second clutch shaft that constantly connects second and third planetary gear sets, and a third clutch shaft that constantly connects the third and first planetary gear sets. A drive shaft is constantly connected to the fourth planetary gear set; an output shaft is constantly connected to the third planetary gear set. The first planetary gear set is directly connected to two shift elements, the second planetary gear set is directly connected to four shift elements, the third planetary gear set is directly connected to two shift elements, the fourth planetary gear set is directly connected to four shift elements. The drive shaft is directly connected to only one shift element. The output shaft is directly connected to only one shift element.

A transmission for a vehicle may include a first planetary gear set, a second planetary gear set, a third, planetary gear set, and a fourth planetary gear set each including three rotary elements, and a plurality of friction members, in which the friction members are connected to at least one or more of the rotary elements of the planetary gear sets and control rotation of the rotary elements.

A planetary gear train of an automatic transmission includes an input shaft; an output shaft; a first planetary gear set having first to third rotating elements; a second planetary gear set having fourth to sixth rotating elements; a third planetary gear set having seventh to ninth rotating elements; a fourth planetary gear set having tenth to twelfth rotating elements; and seven control elements, wherein the input shaft is continuously connected with the second rotating element, the output shaft is continuously connected with the eleventh rotating element, the second rotating element is continuously connected with the fourth rotating element, the third rotating element is continuously connected with the tenth rotating element, the sixth rotating element is continuously connected with the seventh rotating element, the ninth rotating element is continuously connected with the twelfth rotating element, the third rotating element and the eighth rotating element are selectively connected.

A transmission for a vehicle may include an input shaft, an output shaft, a first planetary gear set, a second planetary gear set, a third, planetary gear set, a fourth planetary gear set, provided to transfer a torque between the input shaft and the output shaft, and friction members, wherein each of the first, second, third, and fourth planetary gear sets includes three rotary elements and three of the friction members are each selectively connected to at least one of the at least three rotary elements of the first, second, third, and fourth planetary gear sets and control rotation of the rotary elements to achieve gear ratios of ten or more steps of forward shifting and one step of reverse shifting in a vehicle.

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 to selectively connect the rotation elements and to selectively connect the rotation elements with a transmission housing.

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 to selectively connect the rotation elements with each other and selectively connect the rotation elements with a transmission housing.

A family of transmission gearing arrangements provides between eight and ten forward speed ratios and a reverse speed ratio. Three planetary gear sets are located on the input axis and a fourth planetary gear set is located on an offset axis. Axis transfer gears convey power between the input axis and the offset axis. One axis transfer gear is supported by a front support while another is supported by a center support. The center support also supports a clutch module and supplies pressurized fluid to engage the clutches in the clutch module.

A transmission device, wherein the compound planetary gear mechanism increases the speed of the power transmitted to the input element and transmits the resultant power to the first and the second output elements when the fixable element is non-rotatably held stationary by the first brake; and the first and the second clutches are disposed on a side closer in the axial direction to the compound planetary gear mechanism than the first and the second planetary gear mechanisms.

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 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.

A an automatic transmission includes: a first planetary gear set including a first, second, and third rotation elements; a second planetary gear set including a fourth, fifth, and sixth rotation elements; a third planetary gear set including a seventh, eighth, and ninth rotation elements; a fourth planetary gear set including a tenth, eleventh and twelfth rotation elements; a first shaft interconnecting the first and fourth rotational elements, and selectively connected to the transmission housing; a second shaft interconnecting the second and seven rotational elements, and connected with an input shaft; a third shaft connected to the third rotational element, and selectively connected to the transmission housing; a fourth shaft connected to the fifth rotational element; a fifth shaft interconnecting the sixth and eleventh rotational elements, and selectively connected to the transmission housing; and a sixth shaft interconnecting the eighth and twelfth rotational element, and connected to an output shaft.