According to one embodiment, a transmission includes a first shaft, a first gear pair, a second gear pair, a synchronization mechanism, and a clutch mechanism. A first sleeve of the synchronization mechanism is movable along the axis of the first shaft between a pressing position, in which the first sleeve presses a second cone surface of a synchronizer ring against a first cone surface of a third gear of the second gear pair, and a non-pressing position in which the first sleeve does not press the second cone surface against the first cone surface. The clutch mechanism transmits rotation between the first shaft and a first gear of the first gear pair and transmits no rotation between the first shaft and the third gear. 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.

According to one embodiment, a transmission includes a first shaft, a first gear pair, a second gear pair, a synchronization mechanism, and a clutch mechanism. A first sleeve of the synchronization mechanism is movable along the axis of the first shaft between a pressing position, in which the first sleeve presses a second cone surface of a synchronizer ring against a first cone surface of a third gear of the second gear pair, and a non-pressing position in which the first sleeve does not press the second cone surface against the first cone surface. The clutch mechanism transmits rotation between the first shaft and a first gear of the first gear pair and transmits no rotation between the first shaft and the third gear. 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.

A dual-shaft clutch varying speed device includes a drive unit, an input shaft, an output shaft, a housing, at least an odd-numbered clutch unit and at least an even-numbered clutch unit. The input shaft having an input gear is coupled with the drive unit. The output shaft, having an end thereof penetrate through the input shaft and the drive unit, has at least an odd-numbered output gear and at least an even-numbered output gear. The housing has a housing gear. The at least one odd-numbered clutch unit being furnished at the inner part of the housing has an odd-numbered clutch shaft and an odd-numbered clutch gear which is meshed with the odd-numbered output gear. The at least one odd-numbered clutch unit has an even-numbered clutch shaft and an even-numbered clutch gear which is meshed with the even-numbered output gear.

A dual-shaft clutch varying speed device includes a drive unit, an input shaft, an output shaft, a housing, at least an odd-numbered clutch unit and at least an even-numbered clutch unit. The input shaft having an input gear is coupled with the drive unit. The output shaft, having an end thereof penetrate through the input shaft and the drive unit, has at least an odd-numbered output gear and at least an even-numbered output gear. The housing has a housing gear. The at least one odd-numbered clutch unit being furnished at the inner part of the housing has an odd-numbered clutch shaft and an odd-numbered clutch gear which is meshed with the odd-numbered output gear. The at least one odd-numbered clutch unit has an even-numbered clutch shaft and an even-numbered clutch gear which is meshed with the even-numbered output gear.

A power generation device includes a main shaft rotated by an external force, a speed-up gear, a high-speed shaft, a rolling bearing, a power generator, and a one-way clutch disposed between the output gear and the high-speed shaft. In a state where the main shaft is rotating in a positive direction, the one-way clutch integrally rotatably connects the output gear and the high-speed shaft to each other if a rotational speed of the output gear exceeds a rotational speed of the high-speed shaft, and breaks connection between the output gear and the high-speed shaft if the rotational speed of the output gear becomes lower than the rotational speed of the high-speed shaft.