Patent ID: 8276473

Claim:
A shift-drum apparatus for a gear transmission comprising a shift drum provided at its outer peripheral surface with a plurality of shift grooves, and a plurality of shift forks that are respectively engaged with the shift grooves while being moved in an axial direction of a shift drum shaft by rotation of the shift drum, in which a plurality of dog clutches of the gear transmission are engaged or disengaged by movement of each of the shift forks, and a state of the gear transmission is shifted between a neutral state and a plurality of transmission gear stages, wherein: the number of the shift forks is the same as the number of the transmission gear stages, each of the shift grooves includes a passage portion extending along a circumferential direction of the shift drum, and one or more gear-shifting recesses that are depressed from the passage portion in an axial direction of the shift drum, the shift forks are biased in the axial direction respectively by springs toward the corresponding gear-shifting recesses, and two of the gear shifting recesses are formed in at least one of the plurality of shift grooves, while two of the shift forks are engaged with the shift groove.