Transmission

A transmission comprising:

• a rotatable first shaft;
• a rotatable second shaft parallel to the first shaft;
• a first gear pair including a first gear and a second gear, the first gear being attached to the first shaft rotatably with respect to the first shaft, the second gear being attached to the second shaft, to be engaged with the first gear and rotate together with the second shaft;
• a second gear pair including a third gear and a fourth gear and being smaller in gear ratio than the first gear, the third gear being attached to the first shaft rotatably with respect to the first shaft, the fourth gear being attached to the second shaft, to be engaged with the third gear and rotate together with the second shaft;
• a synchronization mechanism that is switchably placed in a power transmission state and a power shutoff state, the power transmission state being a state that the synchronization mechanism comes between the first shaft and the third gear, and generates frictional force to cause a rotation speed of the first shaft to approach a rotation speed of the third gear, the power shutoff state being a state that the synchronization mechanism generates no frictional force;
• and
• a clutch mechanism that switches a rotation transmission state between the first shaft and the first gear and between the first shaft and the third gear, wherein
• the synchronization mechanism comprises:
• a first cone surface of the third gear, to rotate together with the third gear;
• a synchronizer ring including a second cone surface to be pressed against the first cone surface to generate the frictional force with the first cone surface;
• and
• a first sleeve that is movable between a pressing position and a non-pressing position in an axial direction of the first shaft and rotates together with the first shaft, the pressing position being a position in which the first sleeve presses the second cone surface against the first cone surface, the non-pressing position being a position in which the first sleeve does not press the second cone surface against the first cone surface;
• and
• the first sleeve is movable from the non-pressing position to the pressing position while the clutch mechanism transmits rotation between the first shaft and the first gear and transmits no rotation between the first shaft and the third gear;
• and
• the clutch mechanism transmits rotation between the first shaft and the first gear while the first sleeve moves from the non-pressing position to the pressing position.