| 摘要 |
A gear-operated speed change apparatus for an automatic transmission, which can make the degree of freedom for selecting a gear ratio higher than that of the case using the Ravigneaux type composite planetary gear train, while achieving a strength advantage of the gear train, an improvement in the fuel economy, coaxial positioning of the input port and output portions and size reduction of the automatic transmission altogether. The apparatus can achieve at least seven forward speeds and one reverse speed by engaging/releasing four clutches and two brakes. One of the three planetary gear sets can reduce the speed of an input rotation always or increase the input rotation always. One of the remaining two planetary gear sets is a double sun gear type planetary gear set including a third carrier having a center member positioned between two sun gears for inputting or outputting a rotation.
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