Patent ID: 7094174

Claim:
An automatic transmission, comprising: an input member; an output member; an auxiliary shift portion including a third planetary gear set having a sun gear, a carrier and a ring gear, a first one of which is coupled to the input member, a second one of which is selectively inhibited from rotating by a third brake, and a third one of which serves the ring gear serving as an intermediate output member and being rotated at a reduced speed as compared with that of the input member to output power; and a main shift portion including a first planetary gear set and a second planetary gear set each of which includes a sun gear, a carrier and a ring gear, at least one of the sun gear, the carrier and the ring gear of the first planetary gear set being coupled to at least one of the sun gear, the carrier and the ring gear of the second planetary gear set to provide a first rotating element, a second rotating element, a third rotating element and a fourth rotating element, the main shift portion further including a first brake that selectively stops rotation of the first rotating element, a second brake that selectively stops rotation of the second rotating element, a first clutch that selectively couples the first rotating element to the input member, and a second clutch that selectively couples the second rotating element to the input member, the fourth rotating element being coupled integrally to the intermediate output member, the third rotating element being coupled integrally to the output member, wherein a first-speed gear stage having the largest gear ratio is established when the second brake and the third brake are engaged, a second-speed gear stage having a smaller gear ratio than that of the first-speed gear stage is established when the first brake and the third brake are engaged, a third-speed gear stage having a smaller gear ratio than that of the second-speed gear stage is established when the first clutch and the third brake are engaged, a fourth-speed gear stage having a smaller gear ratio than that of the third-speed gear stage is established when the second clutch and the third brake are engaged, a fifth-speed gear stage having a smaller gear ratio than that of the fourth-speed gear stage is established when the first clutch and the second clutch are engaged, and a sixth-speed gear stage having a smaller gear ratio than that of the fifth-speed gear stage is established when the second clutch and the first brake are engaged, wherein the first planetary gear set is of a single pinion, and the second planetary gear set is of a single pinion, and the first rotating element comprises the sun gear of the first planetary gear set and the sun gear of the second planetary gear set that are coupled to each other, the second rotating element comprises the carrier of the first planetary gear set and the carrier of the second planetary gear set, the third rotating element comprises the ring gear of the first planetary gear set, and the fourth rotating element comprises the ring gear of the second planetary gear set.