US Patent 7229379 Transmission device for land vehicle, such as a cart

For a first gear ratio, the flyweights engage the clutch and thus connect the input to the sun wheel, whilst the ring gear is immobilised by the free wheel. For the second gear ratio, the flyweights push the ring gear against the axial thrust of the helical teeth in a direction causing the engagement of the clutch against the ring and thus, at the same time, the disengagement of the clutch. The thrust produced by the teeth on the ring gear decreases and transmission then occurs from the input to the ring gear, whilst the sun wheel is immobilised by its free wheel. The speed increases further, the flyweights rise further, compress the prestressed springs and push the ring in the direction of the engagement of the clutch, which produces direct drive.