A method for operating a vehicle drivetrain (1) includes proceeding, in the presence of the demand for activation of the engine start-stop function of the vehicle drivetrain (1) and a simultaneously shut-down drive machine (2), from an operating state of the vehicle drivetrain (1) during which a sailing operating function of the vehicle drivetrain (1) is active, during which the drive machine (2) is decoupled from the drive output (3), during which the positively engaging shift element (F) is open and during which a rotational speed (n_ab) of the drive output (3) is higher than a defined rotational speed at which a rotational speed difference between shift element halves of the positively engaging shift element (F) lies within a rotational speed range within which the positively engaging shift element (F) is transferrable into the closed operating state, and actuating the positively engaging shift element (F) in a closing direction no later than when the defined rotational speed is reached.

A family of transmission gearing arrangements each establish at least one reverse gear ratio and between nine and fifteen forward gear ratios. A shiftable gearing arrangement establishes a variety of speed ratios between the input and a first shaft. In some embodiments, a fixed speed ratio is established upstream or downstream of the shiftable gearing arrangement. In reverse and low gear ratios, a low clutch couples the first shaft to the output. In the high gear ratios, a combining planetary gear set establishes a linear speed relationship between the first shaft, a second shaft rotating at a speed proportional to the input, and the output.

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 a tenth rotation element, an eleventh rotation element, and a twelfth rotation element.

An automatic transmission includes a first planetary gear set, a second planetary gear set, and a first brake. A first sun gear includes a first split sun gear on a drive source side, and a second split sun gear on a side opposite to the drive source. The first spilt sun gear is coupled to the first brake, and is fixed to a transmission case during engagement of the first brake. The second split sun gear is constantly coupled to a second sun gear. An input shaft is constantly coupled to a first carrier while passing through the first split sun gear, and between the first and second split sun gears. An output shaft is constantly coupled to a second carrier.

A dual clutch automatic transmission includes a one-way clutch provided in a driving force transmission path that establishes a certain gear ratio in a first set of gear ratios. A driving transmission direction of the one-way clutch is set such that a rotation inputted from a wheel side to an output member in a predetermined rotational direction is transmitted to the input shaft. The predetermined rotational direction corresponds to a backward movement of a vehicle. On condition that the vehicle has stopped, backward movement prevention control of causing the switching mechanism to engage a transmission gear for another gear ratio in the first set with the input shaft can be executed.

A dual clutch automatic transmission includes a one-way clutch provided in a driving force transmission path that establishes a first certain gear ratio in a first set of gear ratios. A driving transmission direction of the one-way clutch is set such that a rotation inputted from a wheel side to an output member in a predetermined rotational direction is transmitted to the input shaft. The predetermined rotational direction corresponds to a backward movement of a vehicle. If an off-gear operation cannot be performed for a transmission gear with interlock, the driving force of the driving source is input to the input shaft to enable the off-gear operation.

A vehicle makes a notification to prompt a driver to perform a predetermined operation in a case in which a predetermined function of the vehicle is lost, and starts a recovery operation of the function on condition that the predetermined operation is performed.

A dual clutch automatic transmission includes a one-way clutch provided in a driving force transmission path that establishes a certain gear ratio in a first set of gear ratios. A driving transmission direction of the one-way clutch is set such that a rotation inputted from a wheel side to an output member in a predetermined rotational direction is transmitted to the input shaft. The predetermined rotational direction corresponds to a backward movement of a vehicle. On condition that the traveling state of the vehicle reaches a predetermined deceleration state, switching control of setting the gears for the first set to a neutral position can be executed.

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 vehicle transmission having a housing and a main transmission which includes input and output shafts and four planetary gearsets. Each of the gearsets has sun and ring gears, a carrier which supports a planetary gearwheel. The sun gear and the carrier of the second gearset are coupled permanently to the input and output shafts, respectively. The carrier of the second gearset is permanently coupled to the carrier of the fourth gearset. The ring gear of the second gearset is permanently coupled to the ring gear of the third gearset. The carrier of the fourth gearset can be coupled, via a first shifting element, to the sun gear of the second gearset. The carrier of the third gearset can be coupled, via a second shifting element, to the housing. The sun gear of the third gearset can be coupled, via third and fourth shifting elements, to the input shaft.