A first carrier rotates integrally with an input shaft. A third sun gear and a fourth sun gear rotate integrally with a first intermediate shaft. A third carrier rotates integrally with a second ring gear. A fourth carrier rotates integrally with a third ring gear, and outputs power. A first clutch couples a first ring gear and a second sun gear to the first intermediate shaft. A second clutch couples the first carrier to a second carrier. A third clutch couples the second carrier to the first intermediate shaft. A first brake brakes rotation of a first sun gear. A second brake brakes rotation of the second ring gear and the third carrier. A third brake brakes rotation of a fourth ring gear.

A planetary gear train of an automatic transmission for a vehicle may include a first planetary gear set, a second planetary gear set, a third planetary gear set, a fourth planetary gear set, an input shaft, an output shaft disposed in parallel with the input shaft, a first connecting member, a second connecting member, a third connecting member, a fourth connecting member, a fifth connecting member, a sixth connecting member connected to the input shaft selectively, a seventh connecting member engaged with the second connecting member, an eighth connecting member directly connected with the output shaft, and transfer gears connected with the connecting members.

A planetary gear train of an automatic transmission for a vehicle may include a first planetary gear set, a second planetary gear set, a third planetary gear set, a fourth planetary gear set, an input shaft mounted with the first and second planetary gear sets at an external circumference of the input shaft, an output shaft disposed in parallel with the input shaft and mounted with the third and fourth planetary gear sets on an external circumference of the output shaft, a first shaft, a second shaft, a third shaft directly connected with the input shaft, a fourth shaft, a fifth shaft, a sixth shaft gear-meshed with the fourth shaft, a seventh shaft engaged with the third shaft selectively, an eighth shaft directly connected with the output shaft, a ninth shaft, and transfer gears each gear-meshed with at least one of the shafts.

A multi-speed automatic transmission includes a housing, a transmission input shaft, and a plurality of clutches. Different combinations of clutches of the plurality of clutches are engaged to generate different gear ratios corresponding to respective forward speeds of the automatic transmission. The plurality of clutches are positioned within the housing and include a first friction clutch coupled the input shaft and having a first hub, and a second friction clutch having a second clutch hub. The second friction clutch is disposed about the input shaft and radially nested within the first clutch hub such that the second friction clutch is positioned radially between the first clutch hub and the input shaft. The first friction clutch is engaged to generate at least two forward speeds of the transmission and the second friction clutch is engaged to generate seven forward speeds of the transmission including the two forward speeds.

A planetary gear train of an automatic transmission for a vehicle may include a first planetary gear set, a second planetary gear set, a third planetary gear set, a fourth planetary gear set, an input shaft mounted with the first, second, and third planetary gear sets at an external circumference of the input shaft, an output shaft disposed in parallel with the input shaft and mounted with the fourth planetary gear set on external circumference of the output shaft, a first shaft, a second shaft directly connected with the input shaft, a third shaft, a fourth shaft gear-meshed with the output shaft, a fifth shaft, a sixth shaft, a seventh shaft, an eighth shaft, a ninth shaft directly connected with the output shaft, a tenth shaft, and transfer gears, each gear-meshed with at least one of the shafts.

An automatic transmission system includes a housing containing automatic transmission fluid (ATF), a plurality of clutches configured to be engaged to generate gear ratios corresponding to forward speeds of the automatic transmission, wherein one clutch of the plurality of clutches is a friction clutch movable between a disengaged state, an engaged state utilized to create one or more gear ratios of the automatic transmission, and a slippingly engaged state between the disengaged state and the engaged state where the friction clutch is not engaged to create a gear ratio of the automatic transmission, and a controller configured to selectively move the friction clutch to the slippingly engaged state when the friction clutch is not being utilized to generate the one or more gear ratios, such that the friction clutch generates heat from friction to thereby rapidly heat the ATF in the housing and improve operating efficiency of the transmission.

A planetary gear train of an automatic transmission for a vehicle may include a first planetary gear set, a second planetary gear set, a third planetary gear set, a fourth planetary gear set, an input shaft mounted with the first, second, and third planetary gear sets at an external circumference of the input shaft, an output shaft disposed in parallel with the input shaft and mounted with the fourth planetary gear set on an external circumference of the output shaft, a first shaft directly connected with the input shaft, a second shaft, a third shaft, a fourth shaft, a fifth shaft, a sixth shaft, a seventh shaft, an eighth shaft directly connected with the output shaft, and selectively gear-meshed with the fifth shaft, and a ninth shaft.

A planetary gear train of an automatic transmission for a vehicle including a first planetary gear set, a second planetary gear set, a third planetary gear set, a fourth planetary gear set, an input shaft mounted with the first, second, and third planetary gear sets at an external circumference of the input shaft, an output shaft mounted with the fourth planetary gear set on an external circumference of the output shaft, a first shaft, a second shaft, a third shaft, a fourth shaft, a fifth shaft, a sixth shaft, a seventh shaft gear-meshed with one shaft among the fifth and sixth shafts, an eighth shaft directly connected with the output shaft, a ninth shaft gear-meshed with a remaining shaft among the fifth and sixth shafts that is not gear-meshed with the seventh shaft, and transfer gears.

A transmission includes first and second input shafts connected via a first clutch to a power source, an output shaft, a first shift gear group including shift gears arranged between the first input and output shafts, a first switching mechanism including a synchronizer for selecting one shift gear from the group, a second shift gear group including shift gears arranged between the second input shaft and the output shaft, and a second switching mechanism including a synchronizer for selecting one shift gear from the group. In order to learn a synchronizer balk position, either the first or second shift gear group, where no targeted synchronizer belongs, is set to any shift gear, both the first and second clutches are engaged, the balk position of the synchronizer is detected in a process of the targeted synchronizer being slid, and information specifying the detected position is stored.

A planetary gear train of an automatic transmission for a vehicle may include a first planetary gear set, a second planetary gear set, a third planetary gear set, a fourth planetary gear set, an input shaft mounted with the first, second, and third planetary gear sets at an external circumference of the input shaft, an output shaft mounted with the fourth planetary gear set on an external circumference of the output shaft, a first shaft directly connected with the input shaft, a second shaft, a third shaft, a fourth shaft, a fifth shaft, a sixth shaft, a seventh shaft, an eighth shaft gear-meshed with one shaft among the fourth and seventh shafts, a ninth shaft directly connected with the output shaft, a tenth shaft gear-meshed with a remaining shaft among the fourth and seventh shafts that is not externally gear-meshed with the eighth shaft, and transfer gears.