Planetary gear train of automatic transmission for vehicles

A planetary gear train of an automatic transmission for vehicles achieving multiple shift-speeds, the planetary gear train comprising:

• an input shaft adapted to receive engine torque;
• an output shaft adapted to output a shifted torque;
• a first planetary gear set being a single pinion planetary gear set having a first sun gear, a first planet carrier, and a first ring gear;
• a second planetary gear set being a double pinion planetary gear set having a second sun gear, a second planet carrier, and a second ring gear;
• a Ravigneaux compound planetary gear set having a third sun gear, a fourth sun gear, a planet carrier, and a ring gear;
• a first rotational member including the first sun gear and selectively connected to the input shaft;
• a second rotational member including the first planet carrier and the second sun gear, and directly connected to a transmission housing;
• a third rotational member including the first ring gear, the second ring gear, and the third sun gear;
• a fourth rotational member including the second planet carrier and selectively connected to the input shaft;
• a fifth rotational member including the planet carrier, and selectively connected to the input shaft or to the transmission housing;
• a sixth rotational member including the ring gear and directly connected to the output shaft;
• a seventh rotational member including the fourth sun gear and selectively connected to the input shaft;
• and
• six friction members including clutches interposed between a selected rotational member among the seven rotational members and the input shaft or between selected rotational members, and brakes interposed between a selected rotational member among the rotational members and the transmission housing.

A planetary gear train of an automatic transmission for vehicles achieving multiple shift-speeds, the planetary gear train comprising:

• an input shaft adapted to receive engine torque;
• an output shaft adapted to output a shifted torque;
• a first planetary gear set having a first sun gear, a first planet carrier, and a first ring gear;
• a second planetary gear set having a second sun gear, a second planet carrier, and a second ring gear;
• a compound planetary gear set formed by combining a third planetary gear set having a third sun gear, a third planet carrier, and a third ring gear and a fourth planetary gear set having a fourth sun gear, a fourth planet carrier, and a fourth ring gear;
• a first rotational member including the first sun gear and selectively connected to the input shaft;
• a second rotational member including the first planet carrier and the second sun gear, and directly connected to a transmission housing;
• a third rotational member including the first ring gear, the second ring gear, and the third sun gear;
• a fourth rotational member including the second planet carrier and selectively connected to the input shaft;
• a fifth rotational member including the third planet carrier and the fourth ring gear, and selectively connected to the input shaft or to the transmission housing;
• a sixth rotational member including the third ring gear and the fourth planet carrier, and directly connected to the output shaft;
• a seventh rotational member including the fourth sun gear and selectively connected to the input shaft;
• and
• six friction members including clutches interposed between a selected rotational member among the seven rotational members and the input shaft or between selected rotational members, and brakes interposed between a selected rotational member among the seven rotational members and the transmission housing.