Transmission

A transmission apparatus comprising:

• a planetary gear set including a first rotation element, a second rotation element and a third rotation element;
• a dog clutch provided to selectively fix one rotation element among the first rotation element, the second rotation element and the third rotation element of the planetary gear set to a stationary member;
• an input shaft and an output shaft respectively connected to two remaining rotation elements of the planetary gear set among the first rotation element, the second rotation element and the third rotation element of the planetary gear set;
• a friction clutch provided to vary frictional force between two arbitrary rotation elements among the first rotation element, the second rotation element and the third rotation element of the planetary gear set;
• a linear actuator provided to transmit linear displacement to apply pressure to the friction clutch;
• a push member provided to receive the linear displacement transmitted from the linear actuator and to apply the pressure to the friction clutch to increase the frictional force of the friction clutch;
• 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 of the dog clutch and the push member to move the sleeve in a direction of engaging the dog clutch when the push member is moved in the direction of releasing the frictional force of the friction clutch;
• and
• a release spring provided to elastically support the sleeve with respect to the push member in a direction of releasing the dog clutch.