| 摘要 |
PROBLEM TO BE SOLVED: To provide an automatic transmission capable of achieving eight forward shift stages and one backward shift stage while reducing a size and costs.SOLUTION: An automatic transmission has a first Ravigneaux-type planetary gear, a second Ravigneaux-type planetary gear, and six engagement elements, ans is composed of a first engagement element for selectively connecting a first sun gear and a third ring gear, a second engagement element for selectively connecting a first carrier and a forth sun gear, a third engagement element for selectively connecting the first sun gear and a third sun gear, a forth engagement element for selectively connecting a first ring gear and the third sun gear, a fifth engagement element for selectively fixing the first sun gear to a transmission case, and a sixth engagement element for selectively fixing a second sun gear to the transmission case. An input shaft is constantly connected to the first carrier, an output shaft is constantly connected to a second carrier, and at least eight forward shift stages and one backward shift stage can be achieved by combination of simultaneous engagements of three of six engagement elements.SELECTED DRAWING: Figure 1 |
