STEPPED AUTOMATIC TRANSMISSION DEVICE AND MOTORCYCLE WITH THE SAME

摘要

A stepped automatic transmission device provided with not less than four speeds and having a novel structure with a simple construction. The transmission device (31) has an input shaft (52), a first rotating shaft (53), a second rotating shaft (54), and a third rotating shaft (64) that are arranged in the front-rear direction. The input shaft (52) is provided with an upstream clutch group (81) having a first clutch (55) and a second clutch (59). The first and second clutches (55, 59) are provided with a first shift gear pair (86) and a second shift gear pair (83), respectively. The second rotating shaft (54) is provided with a downstream clutch group (82) having a third clutch (70) and a fourth clutch (66). The third and fourth clutches (70, 66) are provided with a third shift gear pair (91) and a fourth shift gear pair (90). The upstream and downstream clutch groups (81, 82) are arranged at positions at which at least respective portions of the groups overlap on each other in the direction of the axis of the input shaft (52).