2080452-A is referenced by 52 patents.
A variable speed gear box, particularly a hub gear box for a pedal cycle wheel, comprises a rotatable input member driving the planet carrier 14 of an epicyclic gear train having also an annular gear and a sun gear 10. The annular gear 9 is integral with or is attached to an output or driven member 1 rotatable relatively to the input or driving member 5. A variable ratio drive means 16 acts between the planet gear carrier 11 and the sun gear 10 of the epicyclic gear train and its ratio is adjusted between a value greater than unity and a value less than unity, thereby to vary the rotational speed of the output member.; Where the gear box is a hub gear box of a pedal cycle, the input or driving member of the gear box is rotatable by the driven sprocket of the cycle, the output or driven member of the gear box is the housing of the gear box and the hub of the wheel and the variable ratio drive is changed by a cable 19 movable axially of the gear box and the wheel in one direction against the force of a return spring 23 by an angularly-oscillatable arm carrying an idler sprocket wheel engaging the driving run of the driving chain of a cycle, the arm being biased by spring means in a direction to maintain the driving run of the chain in tension.