Patent ID: 6887178

Claim:
An automatic transmission, comprising: an input member; an output member; a first transmitting portion including the input member that is rotated at reduced speed to output power from an intermediate output member, and a second transmitting portion including a second planetary gear set and a third 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 second planetary gear set being coupled to at least one of the sun gear, the carrier and the ring gear of the third planetary gear set to provide a first rotating element, a second rotating element, a third rotating element and a fourth rotating element, which are arranged in the order of description from one end to the other end in a nomogram in which speeds of rotation of the first, second, third and fourth rotating elements are represented by straight lines, the second transmitting 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 fourth rotating element to the intermediate output member, a second clutch that selectively couples the first rotating element to the intermediate output member, a third clutch that selectively couples the second rotating element to the input member, and a fourth clutch that selectively couples the first rotating elements to the input member, the third rotating element being integrally coupled to the output member to output power, wherein a first-speed gear stage having the largest gear ratio is established when the first clutch and the second 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 clutch and the first 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 second clutch are engaged, and a fourth-speed gear stage having a smaller gear ratio than that of the third-speed gear stage is established when the first clutch and the fourth clutch 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 third clutch are engaged, a sixth-speed gear stage having a smaller gear ratio than that of the fifth-speed gear stage is established when the third clutch and the fourth clutch are engaged, a seventh-speed gear stage having a smaller gear ratio than that of the sixth-speed gear stage is established when the second clutch and the third clutch are engaged, an eighth-speed gear stage having a smaller gear ratio than that of the seventh-speed gear stage is established when the third clutch and the first brake are engaged.