Importance

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Abstract

An overdrive transmission for a motor vehicle has a housing with a rotatably mounted driving shaft and a rotatably mounted driven shaft. A planetary gear device is used to transmit power from the driving shaft to the driven shaft. In two of the illustrated embodiments, when the transmission is in the direct drive mode the planet gear carrier of the planet gear device is allowed to rotate and is engaged with the driven shaft by a clutch for power transmission at a 1:1 ratio, and when in the overdrive mode the planet gear carrier is prevented from rotation by another clutch and is disengaged from the driven shaft for power transmission to the driven shaft through the planetary gears of the planetary gear device at an increased gear ratio. In another of the illustrated embodiments, when the overdrive transmission is in the direct drive mode the sun gear of the planetary gear device is engaged with the driving shaft by a clutch and the planet carrier of the planetary gear device is connected to the driven shaft for power transmission at a 1:1 ratio, and when in the overdrive mode the sun gear is prevented from rotating by another clutch and is disengaged from the driving shaft so that power is transmitted from the driving shaft to the driven shaft through the planet gears of the planetary gear device at an increased gear ratio. In further embodiments, the overdrive transmissions are provided with neutral modes while being shifted between overdrive and direct drive modes.

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First Claim