Abstract: A transmission apparatus may include a planetary gear set including three rotation elements, a dog clutch provided to selectively fix one rotation element of the planetary gear set, input and output shafts connected to two remaining rotation elements, a friction clutch provided to vary frictional force between two arbitrary rotation elements, a linear actuator provided to form linear displacement, a push member provided to receive the linear displacement and to apply pressure to the friction clutch to increase frictional force thereof, a return spring elastically supporting the push member in a direction of releasing the frictional force of the friction clutch, a one-way interlocking structure provided between a sleeve and the push member, and a release spring provided to elastically support the sleeve with respect to the push member in a direction of releasing the dog clutch.

Abstract: A planetary gear train of an automatic transmission for a vehicle provides at least ten forward speed stages and one reverse speed stage by combination of: first to fourth planetary gear sets respectively having first to third rotation elements, fourth to sixth rotation elements, seventh to ninth rotation elements, or tenth to twelfth rotation elements; first to eighth shafts; at least four clutches and two brakes. In particular, the first shaft is fixedly connected to the first and fourth rotation elements and selectively connected to a transmission housing, the second shaft is fixedly connected to the second rotation element and an input shaft, the third shaft is fixedly connected to the fifth, eighth and twelfth rotation elements, the fourth shaft is fixedly connected to the ninth and tenth rotation elements and selectively connected to the input shaft.

Abstract: A planetary gear train of an automatic transmission for a vehicle provides at least ten forward speed stages and one reverse speed stage by combination of: first to fourth planetary gear sets respectively having first to third rotation elements, fourth to sixth rotation elements, seventh to ninth rotation elements, or tenth to twelfth rotation elements; first to eighth shafts; at least four clutches and two brakes. In particular, the first shaft is fixedly connected to the first and fourth rotation elements and selectively connected to a transmission housing, the second shaft is fixedly connected to the second rotation element and an input shaft, the third shaft is fixedly connected to the fifth, eighth and twelfth rotation elements, the fourth shaft is fixedly connected to the ninth and tenth rotation elements and selectively connected to the input shaft.