| 摘要 |
A variable-speed drive unit for a chain drive comprising a drive wheel (12) which contains a series of radially mounted threaded rods (14) which pass through internally threaded blocks (22), upon which are selectively mounted free wheeling sprockets (28) and rigidly connected driving sprocket segments (30); the radially inner end portions of the threaded rods (14) being rotatably mounted into a hub (10) and rigidly attached to a primary bevel gear (34) which engages secondary bevel gears (36) (38) mounted on either side thereof; the secondary bevel gears (36) (38) being attached to actuator disks (40) (42) mounted on either side of the unit; the actuator disks (40) (42) being disposed for selective engagement by spring biased actuator arms (54) (56) whereby the associated bevel gears (34) (36) (38) will be rotated thus moving the blocks (22) selectively up or down the threaded rods (14) so as to effectively vary the diameter of a circle described by the chain sprockets (28) and sprocket segments (30) as they are rotated.
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