Automatic transmission

An automatic transmission, comprising:

• an input member connectable to an engine;
• an output member;
• a fixed portion;
• and
• a Ravigneaux planetary gear unit including a first sun gear, a second sun gear, a first pinion gear meshed with the second sun gear, a second pinion gear meshed with the first pinion gear and the first sun gear, a carrier rotatably supporting the first pinion gear and the second pinion gear and a ring gear meshed with the second pinion gear,
• wherein
• the first sun gear is constantly connected to a motor/generator and connectable to the input member due to engagement of a first clutch and fixable to the fixed portion due to engagement of a second brake,
• the carrier is connectable to the input member due to engagement of a second clutch and fixable to the fixed portion due to engagement of a third brake,
• the ring gear is constantly connected to the output member,
• the second sun gear is fixable to the fixed portion due to engagement of a first brake,
• a first speed is established due to engagement of both the first clutch and the first brake,
• a second speed whose speed change ratio is smaller than that of the first speed is established due to engagement of the second clutch,
• a third speed whose speed change ratio is smaller than that of the second speed is established due to engagement of both the first clutch and the second clutch,
• a fourth speed whose speed change ratio is smaller than that of the third speed is established due to engagement of both the second clutch and the second brake,
• a reverse stage is established due to engagement of both the first clutch and the third brake, and
• a stepless speed change is established by engaging the second clutch and varying the rotation speed of the motor/generator, and
• wherein
• the input member is arranged in an inner circumference of the Ravigneaux planetary gear unit,
• the second clutch and the third brake are arranged at one axial end side of the Ravigneaux planetary gear unit,
• the first brake is arranged at the other axial end side of the Ravigneaux planetary gear unit,
• the first clutch and the second brake are arranged at the other axial end side of the Ravigneaux planetary gear unit and placed at positions farther away than the first brake in distance from the Ravigneaux planetary gear unit, and
• the motor/generator is constantly connected to the first sun gear through a way that extends in and along a space defined between the first brake and the second brake and a space defined between an inner circumference side of the second sun gear and an outer circumference side of the input member.