| 摘要 |
<p>Sprocket segments (28, 28a) having peripheral teeth (38) are mounted on sprocket housings (78, 78a), stationary relative to each other, so that the combined periphery of the sprocket segments (28, 28a) is circular. The sprocket segments (28, 28a) are slidable, relative to the housing (78), radially to vary the diameter of the combined sprocket segments (28, 28a). Each sprocket segment (28) is formed from hinged subsegments (30, 32, 34, 36), with each subsegment (30, 32, 34, 36) having a single tooth (38). One housing (78) sprocket segments (28) overlap the adjacent housing (78a) sprocket segments (28a) to form a single tooth (38a). The sprockets (28, 28a) are movable angularly relative to the housing (78, 78a), and, with the segments (28, 28a) radial displacement, the number of effective teeth (38) on the sprocket assembly (16) can be varied in increments of one tooth (38). A shift actuator (152) contacts a latch mechanism (128) to cause disengagement of the latch (128) and angular displacement of the sprocket segments (28, 28a). Movement of the shift actuator (152) is accomplished manually or automatically through a motor (238) and an electronic control system (400, 700, 1500, 704).</p> |
