Patent attributes
A planetary gear train of an automatic transmission for a vehicle may include: an input shaft receiving torque of an engine; an output shaft outputting torque; a direction changer disposed on an input shaft side and transmitting the torque of the engine to the input shaft with or without change of rotation direction, or disposed on an output shaft side and outputting the torque of the output shaft with or without change of rotation direction; a first planetary gear set including first, second and third rotation elements; a compound planetary gear set including fourth, fifth, sixth, and seventh rotation elements by combining second and third planetary gear sets; a fourth planetary gear set including eighth, ninth, and tenth rotation elements.