| 摘要 |
A speed change device for shifting the gear of a transmission by using a cylindrical drum that reciprocally moves and rotates, featuring the structure of a compact size and excellent operability. To execute the shifting operation, the speed change device of the invention uses a cylindrical drum 4 that reciprocally moves in the axial direction and is rotatably supported. Fork pins FP1 to FP4 coupled to a plurality of forks of the transmission are fitted into drum grooves 41 to 44 formed in the cylindrical surface of the cylindrical drum. In each drum groove, there are formed small width portions of a width nearly equal to that of the fork pin and large width portions wider than the small width portions in a manner that the fork pin positioned at the small width portion is shifted. To shift the gear, the cylindrical drum 4 is rotated by a select motor 6 to select the fork pin positioned at the small width portion. Next, a threaded shaft 1 is rotated by a shift motor 7 to move the cylindrical drum 4 in the axial direction to thereby shift the selected fork pin. |
