Patent ID: 6935985

Claim:
A gear change-speed unit for an automatic transmission, comprising: an input part which receives rotation of a power source; an output part arranged coaxially with the input part; planetary-gear sets which provide transfer paths between the input and output parts; and clutches and brakes arranged to be engaged and released selectively, the clutches and brakes selecting one of the transfer paths of the planetary-gear sets to change rotation of the input part at a corresponding gear ratio and provide it to the output part, the clutches and brakes allowing at least 6 forward speeds and 1 reverse speed by a combination of engagement and release of the clutches and brakes, the first planetary-gear set comprising a reduction planetary-gear set reducing input rotation at all times, the second planetary-gear set comprising a second sun gear, a second pinion meshed with the second sun gear, a second ring gear meshed with the second pinion, and a second carrier supporting the second pinion, the third planetary-gear set comprising third and fourth sun gears, a third pinion meshed with the third and fourth sun gears, a third ring gear meshed with the third pinion, and a third carrier receiving and providing rotation between the third and fourth sun gears through a center member coupled to a side member which rotatably supports the third pinion, the third sun gear being close to the input part, the fourth sun gear being distant from the input part, the second and third planetary-gear sets constituting a change-speed planetary-gear set, and the first, second, and third planetary-gear sets being disposed in parallel in this order from the side of the input part.