Automatic mechanically controlled continuously-variable-ratio drive

摘要

A continuously-variable-ratio drive (1), having an input shaft (2); a flywheel (10) integral with the input shaft; a drive pulley (6) idle with respect to the input shaft and defined by two half-pulleys (6a, 6b) defining a groove (8) of variable size for a V belt (C); and a centrifugal control assembly (36). The control assembly (36) has a centrifugal actuating device (42) which intervenes above a first threshold value of the angular speed of the input shaft (2) to connect the drive pulley (6) angularly to the flywheel (10) by means of a friction clutch (32); and a speed adjusting device (43) which is active over a second threshold value of the angular speed of the input shaft (2) to adjust the size of the groove (8) of the drive pulley (6) and therefore the work diameter of the belt (C).