| 摘要 |
A power train of an automatic transmission is provided to facilitate a skip shift process by decreasing the number of friction elements which are applied or released during a skip up or skip down shift. A deceleration unit(400) includes a fixed input member fixed on an input shaft(100), first and second variable brake members connected to a transmission case(300), and a fixed connection member. The deceleration unit generates first and second deceleration rotation speeds by using the fixed input member and the first and second variable brake members. An output unit(500) includes a first variable input member fixed on the fixed connection member and variably connected to the input shaft, a second variable input member variably connected to the input shaft, third and fourth variable brake members connected to the transmission case, and an output member fixed on an output gear(200). The output unit generates seven forward speeds and three backward speeds by using the first and second variable input members and the third and fourth variable brake members. A first clutch(C1) variably couples the first variable input member with the input shaft. A second clutch(C2) variably couples the second variable input member with the input shaft. A first brake(B1) variably brakes the third variable brake member. A second brake(B2) variably brakes the first variable brake member. A third brake(B3) variably brakes the second variable brake member. A fourth brake(B4) variably brakes the fourth variable brake member.
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