| 摘要 |
A gear speed-changing apparatus can be obtained having made 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 (e.g., the gear strength or gear lifetime) of the gear train, an improvement in fuel economy, the coaxial layout of the input portion and the output portion and the size reduction of the automatic transmission altogether. The apparatus achieves six forward speeds and one reverse speed by engaging/disengaging three clutches C1, C2 and C3 and two brakes B1 and B2 properly. One G1 of three planetary gearsets G1, G2 and G3 is a speed-reducing device for reducing input speed always. One G3 of the remaining two planetary gearsets G2 and G3 is a double sun gear type planetary gearset, the carrier PC3 of which has a center member CM for inputting or outputting a rotation from between two sun gears S3 and S4. An intermediate wall 2 for defining the inside of a transmission case 1 into one side and the other side, is provided with cylinder chambers of brakes B1 and B2, and a supporting portion 22 for supporting a member 4 serving as a clutch drum of the third clutch C3. <IMAGE>
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