Abstract: A planetary gear train of an automatic transmission for a vehicle may include an input shaft receiving power from an engine, an output shaft outputting power changed in speed, a first planetary gear set, a second planetary gear set, a third planetary gear set, a fourth planetary gear, a first rotating shaft selectively connected with a transmission housing, a second rotating shaft, a third rotating shaft selectively connected with the transmission housing, a fourth rotating shaft directly connected with the input shaft so as to be continuously operated as an input element, a fifth rotating shaft, a sixth rotating shaft selectively connected with the first, second, and fifth rotating shafts, a seventh rotating shaft, an eighth rotating shaft selectively connected with the seventh rotating shaft and simultaneously directly connected with the output shaft, and six friction elements.

Abstract: 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, a second planetary gear set, a third planetary gear set, a fourth planetary gear set, a first rotational shaft, a second rotational shaft, a third rotational shaft, a fourth rotational shaft selectively connected to the first rotational shaft and selectively connected to a transmission housing simultaneously, a fifth rotational shaft selectively connected to the first rotational shaft and directly connected to the input shaft simultaneously, a sixth rotational selectively connected to the transmission housing, a seventh rotational shaft selectively connected to the first and third rotational shafts, an eighth rotational shaft directly connected to the output shaft, and six frictional elements.

Abstract: A multi-stage transmission for vehicle may include an input shaft; and an output shafts; first to fourth planetary gear devices transmitting rotary force between the input and output shafts, each of them having three rotary elements; and at least six shifting elements connected to the rotary elements of the planetary gear devices; wherein first rotary element of the first planetary gear device is permanently connected to the input shaft and second rotary element of the third planetary gear device, second rotary element is installed to be fixable by any one of the shifting elements and variably connected to first rotary element of the third planetary gear device and first rotary element of the fourth planetary gear device, and third rotary element is variably connected to first rotary element of the second planetary gear device and permanently connected to second rotary element of the second planetary gear device.

Abstract: A multi-stage transmission for a vehicle may include an input shaft, an output shaft, first to fourth planetary gear devices disposed between the input shaft and the output shaft to transmit rotary force, each of the first to fourth planetary gear devices having three rotary elements, and at least six shifting elements connected to the rotary elements of the planetary gear devices.

Abstract: A planetary gear train of an automatic transmission for a vehicle may include an input shaft receiving power of an engine, an output shaft outputting shifted power, a first planetary gear set, a second planetary gear set, a third planetary gear set, a fourth planetary gear set, a first rotational shaft selectively connected with a transmission housing, a second rotational shaft, a third rotational shaft selectively connected with the transmission housing, a fourth rotational shaft directly connected with the input shaft to be continuously operated as an input element, a fifth rotational shaft selectively connected with the second rotational shaft, a sixth rotational shaft selectively connected with the second rotational shaft, a seventh rotational shaft directly connected with the output shaft to be continuously operated as an output element, an eighth rotational shaft selectively connected with the input shaft and the sixth rotational shaft, and six frictional elements.

Abstract: A planetary gear train of an automatic transmission for a vehicle may include an input shaft receiving rotary power of an engine, an output shaft outputting the rotary power with rotary speed changed, a first planetary gear set, a second planetary gear set, a third planetary gear set, a fourth planetary gear set, a first rotating shaft operating continuously as an input element by being directly connected with the input shaft, a second rotating shaft selectively connected with a transmission housing, a third rotating shaft, a fourth rotating shaft selectively connected with the transmission housing, a fifth rotating shaft selectively connected with the second rotating shaft, a sixth rotating shaft operating continuously as an output element by being directly connected with the output shaft, a seventh rotating shaft, an eighth rotating shaft selectively connected with the first, the fourth, and the seventh rotating shafts, and six friction elements.

Abstract: A multi-stage transmission for a vehicle may include an input shaft and an output shaft, a first planetary gear device, a second planetary gear device, a third planetary gear device, and a fourth planetary gear device provided between the input shaft and the output shaft so as to transfer a torque and each including three rotating elements, and at least six shifting elements connected to the rotating elements of the first to fourth planetary gear devices.

Abstract: A multi-stage transmission for a vehicle may include an input shaft, an output shaft, first to fourth planetary gear devices disposed between the input shaft and the output shaft to transmit rotary force, each of them having three rotary elements, and at least six shifting elements connected to the rotary elements of the planetary gear devices, wherein a first rotary element of the first planetary gear device is continuously connected to the input shaft and variably connected to a second rotary element of the first planetary gear device, the second rotary element is installed to be fixable by one shifting element of the at least six shifting elements, and a third rotary element of the first planetary gear device is continuously connected to a second rotary element of the second planetary gear device and variably connected to a third rotary element of the third planetary gear device.

Abstract: A planetary gear train of an automatic transmission for a vehicle may include an input shaft receiving rotary power of an engine, an output gear outputting the rotary power with rotary speed changed, a first planetary gear set, a second planetary gear set, a third planetary gear set, a fourth planetary gear set, a first rotating shaft, a second rotating shaft, a third rotating shaft, a fourth rotating shaft selectively connected with the third rotating shaft and a transmission housing simultaneously, a fifth rotating shaft selectively connected with the first rotating shaft and the input shaft simultaneously, a sixth rotating shaft, a seventh rotating shaft selectively connected with the sixth rotating shaft and the transmission housing simultaneously, an eighth rotating shaft selectively connected with the sixth rotating shaft and the output gear simultaneously, and six friction elements.

Abstract: A planetary gear train of an automatic transmission for a vehicle may include an input shaft receiving torque of an engine, an output shaft configured to output 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, and a fourth planetary gear set including tenth, eleventh, and twelfth rotation elements.

Abstract: A multi-stage transmission for a vehicle may include an input shaft, an output shaft, first, second, third and fourth planetary gear devices disposed between the input shaft and the output shaft to transmit rotary force, each of the first, second, third and fourth planetary gear devices having three rotary elements, and at least six shifting elements connected to the rotary elements of the first, second, third and fourth planetary gear devices.

Abstract: A planetary gear train for an automatic transmission of 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, a second planetary gear set, a third planetary gear set, a fourth planetary gear set, a first rotation shaft selectively connected to a transmission housing, a second rotation shaft, a third rotation shaft selectively connected to the transmission housing, a fourth rotation shaft, directly connected to the input shaft, a fifth rotation shaft including the second ring gear and the third and fourth sun gears, a sixth rotation shaft selectively connected to the second rotation shaft, a seventh rotation shaft selectively connected to the second and fourth rotation shafts, an eighth rotation shaft selectively connected to the sixth rotation shaft, and directly connected to the output shaft; and six friction elements.

Abstract: A multi-stage transmission for vehicle includes an input shaft, an output shafts, first to fourth planetary gear devices each having three rotary elements and transmitting rotary forces between the input and output shafts, and at least six shifting elements connected to the rotary elements of the planetary gear devices. Of the first planetary gear device, the first rotary element is permanently connected to the input shaft and the second rotary element of the third planetary gear device, the second rotary element is installed to be fixable by any one of the shifting elements and variably connected to the first rotary element and third rotary element of the second planetary gear device, and the third rotary element is permanently connected to the second rotary element of the second planetary gear device.

Abstract: A transmission for vehicles 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.

Abstract: A planetary gear train of an automatic transmission for a vehicle may include an input shaft receiving torque of an engine, an output shaft configured to output 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, and a fourth planetary gear set including tenth, eleventh, and twelfth rotation elements.

Abstract: A planetary gear train of an automatic transmission for a vehicle may include an input shaft into which power of an engine is input, an output shaft that outputs shifted power, a first planetary gear set, a second planetary gear set, a third planetary gear set, a fourth planetary gear set, a first rotational shaft selectively connected to a transmission housing, a second rotational shaft directly connected to the input shaft, a third rotational shaft selectively connected to the transmission housing, a fourth rotational shaft selectively connected to the first rotational shaft and the second rotational shaft, a fifth rotational shaft, a sixth rotational shaft selectively connected to the first rotational shaft, a seventh rotational shaft directly connected to the output shaft, and selectively connected to the fifth rotational shaft, an eighth rotational shaft, and six friction elements.

Abstract: A transmission for a vehicle includes: 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 for controlling rotation of the rotary elements. The transmission improves fuel efficiency by implementing multiple steps of shifting and improves vehicle driving comfort by using operating points in a low RPM range of an engine.

Abstract: A multi-stage transmission for a vehicle includes an input shaft, an output shaft, first to fourth planetary gear devices disposed between the input shaft and the output shaft to transmit rotary forces and each of them having three rotary elements, and at least six shifting elements connected to the rotary elements of the planetary gear devices. Of the first planetary gear device, the first rotary element is permanently connected to the input shaft and a second rotary element of the third planetary gear device, a second rotary element is installed to be fixable by any one of the shifting elements and variably connected to a first rotary element of the second planetary gear device, and a third rotary element of the first planetary gear device is permanently connected to a second rotary element and variably connected to a first rotary element of the fourth planetary gear device.

Abstract: 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, a second planetary gear set, a third planetary gear set, a fourth planetary gear set, a first rotation shaft selectively connected to a transmission housing, a second rotation shaft, a third rotation shaft selectively connected to the transmission housing, a fourth rotation shaft directly connected to the input shaft, a fifth rotation shaft, a sixth rotation shaft selectively connected to the second rotation shaft or the fifth rotation shaft, a seventh rotation shaft selectively connected to the input shaft, and an eighth rotation shaft directly connected to the output shaft, and selectively connected to the sixth rotation shaft.

Abstract: A transmission for a vehicle includes first, second, third and fourth planetary gear set, and a plurality of friction members. Each planetary gear set includes three rotating elements. The friction elements selectively and operably connect the rotating elements of the planetary gear sets to control rotation of the rotating elements. The transmission improves fuel efficiency by increasing the number of gears and enhances driving stability of the vehicle using an operating point in a low RPM range of the engine.