Patent ID: 7914413

Claim:
An automatic transmission, comprising: an input shaft; a speed-reduction planetary gear that can reduce a rotation of the input shaft and output a reduced rotation; a planetary gear unit that is disposed coaxially to the speed-reduction planetary gear and includes a first rotating element, a second rotating element, a third rotating element, and a fourth rotating element; a first clutch that inputs the reduced rotation to the fourth rotating element; a second clutch that inputs the rotation of the input shaft to the second rotating element; a third clutch that inputs the reduced rotation to the first rotating element, the third clutch including a hydraulic servo with a piston member, a clutch drum and sealing members; a fourth clutch that inputs the rotation of the input shaft to the first rotating element, the fourth clutch including a hydraulic servo with a piston member, a clutch drum and sealing members; a first brake that holds a rotation of the first rotating element stationary; a second brake that holds a rotation of the second rotating element stationary; an output member that is linked to the third rotating element, wherein: at least seven forward speeds and a reverse speed can be established, the first clutch, the third clutch, and the fourth clutch are disposed in an axial direction more toward the speed-reduction planetary gear than the planetary gear unit; friction plates of the first clutch are disposed so as to be offset in the axial direction with respect to friction plates of the third clutch and friction plates of the fourth clutch, the friction plates of the fourth clutch are disposed such that at least a portion of the friction plates of the fourth clutch overlap in a radial direction with the friction plates of the third clutch on an inner peripheral side of the friction plates of the third clutch, the hydraulic servo of the fourth clutch is disposed such that at least a portion of the hydraulic servo of the fourth clutch overlaps in the radial direction with an inner peripheral side of the hydraulic servo of the third clutch, and the sealing members of the third clutch are disposed in the radial direction on an outer peripheral side of the sealing members of the fourth clutch.