Automatic transmission for vehicle

An automatic transmission for a vehicle comprising:

• an input shaft and an output shaft;
• a first planetary gear unit;
• a first engagement unit for stopping one shift element of said first planetary gear unit;
• a planetary gear set having at least four shift elements;
• and
• a first clutch for transmitting rotation of the input shaft to one of the shift elements of the planetary gear set through the first planetary gear unit, in which rotation of the input shaft is transmitted to the output shaft through a selected shift element of said planetary gear set so as to achieve a selected speed stage;
• wherein the first planetary gear unit comprises:
• a first shift element to which rotation of the input shaft is input;
• a second shift element stopped from rotating by said first engagement unit;
• and
• a third shift element for outputting rotation, at a rotational speed different from that of the input shaft, to the fourth shift element of the planetary gear set,
• wherein the first engagement unit comprises a first brake and a first one-way clutch, and the second shift element is stopped from rotating when the first brake or the first one-way clutch is engaged.

An automatic transmission for a vehicle comprising:

• an input shaft and an output shaft;
• a first planetary gear unit;
• and
• a planetary gear set having at least four shift elements, said planetary gear unit and said planetary gear set cooperating to provide multistage shifting;
• wherein the first planetary gear unit comprises:
• a first shift element to which rotation of the input shaft is input through a first clutch,
• a second shift element stopped from rotating by a first one-way clutch or a first brake, and
• a third shift element for outputting, to a fourth shift element of the planetary gear set, rotation at a speed that is reduced relative to rotational speed of said input shaft, wherein the second shift element is stopped from rotating when the first brake or the first one-way clutch is engaged.