Automatic transmission

An automatic transmission comprising:

• a Ravigneaux planetary gear unit comprising a front sun gear, a rear sun gear, a ring gear, a long pinion meshing with the front sun gear and the ring gear, a short pinion meshing with the rear sun gear and the long pinion, and a common carrier on which the long pinion and the short pinion are rotatably supported;
• an input member to which rotation of a drive source is inputted;
• a first friction element that selectively connects the input member and the front sun gear with each other;
• a second friction element that selectively connects the input member and the common carrier with each other;
• a third friction element that selectively fixes the rear sun gear to an automatic transmission case;
• a fourth friction element that selectively fixes the front sun gear to the automatic transmission case;
• a fifth friction element that selectively fixes the common carrier to the automatic transmission case;
• and
• an output member always connected to the ring gear,
• the automatic transmission being capable of establishing four forward speeds and one reverse speed by combination of simultaneous engagement of two friction elements selected from the first to fifth friction elements,
• wherein the output member is disposed on one side of the Ravigneaux planetary gear unit, and
• the first friction element, the second friction element, the third friction element, the fourth friction element, and the fifth friction element are disposed on the other side of the Ravigneaux planetary gear unit,
• the automatic transmission further comprising:
• a first hub supporting the second friction element on an outer circumferential side thereof, the first hub being connected to a first carrier plate disposed at one end of the common carrier on the one side of the Ravigneaux planetary gear unit,
• a second hub supporting the fifth friction element on an outer circumferential side thereof, the second hub being connected to a second carrier plate disposed at the other end of the common carrier on the other side of the Ravigneaux planetary gear unit, and
• a partition member cooperating with the automatic transmission case to define a transmission chamber in which the output member, the Ravigneaux planetary gear unit, and the respective first to fifth friction elements are accommodated;
• wherein the output member is supported on a cylindrical portion extending from the partition member toward the Ravigneaux planetary gear unit in an axial direction of the input member.