AUTOMATIC TRANSMISSION DEVICE

PROBLEM TO BE SOLVED: To provide an automatic transmission device including three planetary gear mechanisms, four clutches, and two brakes, while reducing a dragging loss to improve transmission efficiency of the device.SOLUTION: An automatic transmission device includes three planetary gear mechanisms 10, 20, and 30, four clutches C1-C4, and two brakes B1 and B2. A sun gear 11 of the first planetary gear mechanism 10 is connected to a ring gear 32 of the third planetary gear mechanism 30 by a first connection element 51. A sun gear 21 of the second planetary gear mechanism 20 is connected to a sun gear 31 of the third planetary gear mechanism 30 by a second connection element 52. An input shaft 3 is connected to a carrier 22 of the second planetary gear mechanism 20. An output gear 4 is connected to a ring gear 13 of the first planetary gear mechanism 10. Three of the clutches C1-C4 and brakes B1 and B2 are engaged together while the other three are released, thereby forming a forward first gear position to a forward eighth gear position as well as a reverse gear position.