A multi-speed transmission including a plurality of planetary gearsets and a plurality of selective couplers to achieve at least ten forward speed ratios is disclosed. The plurality of planetary gearsets may include a first planetary gearset, a second planetary gearset, a third planetary gearset, and a fourth planetary gearset. The plurality of selective couplers may include a number of clutches and a number of brakes. The multi-speed transmission may have four planetary gearsets and seven selective couplers. The seven selective couplers may include three clutches and four brakes.

A clutch includes a clutch disk that rotates by receiving motive power from an engine and a clutch plate switched between an engaged state in which it is engaged with the clutch disk and a disengaged state in which it is not engaged with the clutch disk. A controller calculates a coefficient of friction μ between the clutch disk and the clutch plate based on a time period Δt elapsed from a first time point when the number of relative rotations of the clutch disk and the clutch plate attains to a first number of rotations to a second time point when a second number of rotations smaller than the first number of rotations is attained, in a state in which the clutch disk rotates while transfer of motive power from the engine to the clutch disk is cut off and in the engaged state.

A multiple speed transmission includes an input member, an output member, first, second, third and fourth planetary gearsets each having first, second and third members, and a plurality of interconnecting members each connected between at least one of the first, second, third, and fourth planetary gearsets and at least another of the first, second, third, and fourth planetary gearsets. The transmission includes a plurality of torque-transmitting mechanisms between the input and output members, wherein the torque transmitting mechanisms are selectively engageable in combinations of at least four to establish at least ten forward speed ratios between the input member and the output member.

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 transmission for a motor vehicle has an input shaft, output shaft, first and second minus planetary gear sets, and first electric machine with a rotationally fixed stator and a rotatable rotor connectable to the input shaft. The first planetary gear set is stepped and has planet gears of a larger and a smaller effective diameter. In the first planetary gear set, first sun gear engages the larger planet gears and is connected or connectable to the rotor; second sun gear engages the smaller planet gears and is connected to a sun gear of the second planetary gear set and connectable to the input shaft; a carrier is connected to a ring gear of the second planetary gear set; and a ring gear is rotationally fixable. In the second planetary gear set, the carrier is connectable to the input shaft and the ring gear is connected to the output shaft.

A multi-speed transmission in planetary design for a vehicle includes a housing, a first shaft is provided as a drive (An), and a second shaft provided as an output arranged axially parallel to the drive. Three planetary gear sets and additional shafts along with six shifting elements are provided. Machine elements (ST1, ST2) are provided for transfer of torque between the drive (An) and the output (Ab). The first shaft (1) is connectable to the ring gear of the third planetary gear set, to the sun gear of the first planetary gear set, to the sun gear of the third planetary gear set, to the planetary gear carrier of the first planetary gear set and to the first machine element. The second shaft is connected or connectable to the first machine element and to the second machine element.

A transmission (G) is provided with 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 second shift element (B2) and/or the fifth shift element (K3) is arranged, in a series at a sixth shift element (K4), in the power flow between the fifth shaft (W5) and a sun gear (So-P4) of the fourth planetary gear set (P4).

A planetary gear train of an automatic transmission for a vehicle having an input shaft for receiving torque of an engine; an output shaft for outputting 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; and a fourth planetary gear set including tenth, eleventh, and twelfth rotation elements, improves power delivery performance and fuel economy by achieving at least ten forward speed stages.

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.

An automatic transmission has eight rotatable shafts, four planetary gear sets and seven shift elements for shifting several forward gears and one reverse gear. A first element of the second planetary gear set forms the first shaft designed as the drive shaft of the transmission. A second element of the third planetary gear set forms the second shaft designed as the output shaft of the transmission. A second element of the first planetary gear set forms the third shaft. A first element of the first planetary gear set forms the fourth shaft. A third element of third planetary gear set forms the fifth shaft. As the sixth shaft, a third element of the first planetary gear set, a second element of the second planetary gear set and a first element of the third planetary gear set are constantly connected. A third element of the second planetary gear set forms the seventh shaft. A first brake is arranged in the power flow between the third shaft and the housing. A second brake is arranged in the power flow between the fourth shaft and the housing, a third brake is arranged in the power flow between the fifth shaft) and the housing. A first clutch (C1) is arranged in the power flow between the first and the seventh shafts. A second clutch is arranged in the power flow between the first and third shafts. A third clutch is constantly connected to the eighth shaft. A fourth clutch is in the power flow between the first and fourth shafts.