Abstract: A reverse gear mechanism in a vehicle gear transmission having a first shaft, a second shaft, and gear trains associated with the first and second shafts for transmitting the torque from one of the first and second shafts to the other. The reverse gear mechanism includes a reverse drive gear supported on the first shaft, a reverse driven gear supported on the second shaft, and an idle gear assembly interposed in meshing relation between the reverse drive and driven gears. The idle gear assembly is composed of a third shaft, a first idle gear supported on the third shaft and meshing with the reverse drive gear, a second idle gear supported on the third gear and meshing with the reverse driven gear, and a clutch unit interposed between the first and second idle gears for limiting the torque transmitted between the first and second idle gears to a prescribed value. The components of the power transmission mechanism can be designed reasonably and advantageously.

Abstract: A power transmission apparatus for vehicles provided with a front wheel driving device for connecting an output shaft of a power unit to front wheels and a rear wheel driving device for connecting the output shaft to rear wheels, wherein a unidirectional clutch is provided in the front wheel driving device, which clutch comprises an outer member, an inner member and a clutch roller, and is capable of transmitting a driving force only in one direction from a power unit side to a front wheel side.