US Patent 10138984 Planetary gear train of vehicle automatic transmission

A planetary gear train of an automatic transmission for a vehicle includes an input shaft, an output shaft, a first planetary gear set including first, second and third rotation elements, a second planetary gear set including fourth, fifth and sixth rotation elements, a third planetary gear set including seventh, eighth and ninth rotation elements, a fourth planetary gear set including tenth, eleventh and twelfth rotational elements, a first shaft, a second shaft, a third shaft, a fourth shaft, a fifth shaft connecting the sixth rotational element to the seventh rotational element and selectively connected to the input shaft or the third shaft, a sixth shaft connecting the eighth rotational element to the twelfth rotational element, a seventh shaft connected to the ninth rotational element, and an eighth shaft connected to the eleventh rotational element, selectively connected to the fourth shaft and directly connected to the output shaft.