A bicycle gear hub includes an axle, planetary gear modules, one-way clutches and a shift mechanism. The planetary gear modules are connected in series at the axle. The shift mechanism includes a shift actuator and control pawls movably disposed at different positions of the axle. The shift actuator includes recess portions to control opening and closing of a control protrusion of one control pawl, and further to control a sun gear of the corresponding planetary gear module to the axle. When a high gear is shifted to a low gear, a rotational direction of the shift actuator is identical to a rotational direction for closing the control pawl.

A bicycle gear hub includes an axle, planetary gear modules, one-way clutches and a shift mechanism. The planetary gear modules are connected in series at the axle. The shift mechanism includes a shift actuator and control pawls movably disposed at different positions of the axle. The shift actuator includes recess portions to control opening and closing of a control protrusion of one control pawl, and further to control a sun gear of the corresponding planetary gear module to the axle. When a high gear is shifted to a low gear, a rotational direction of the shift actuator is identical to a rotational direction for closing the control pawl.

The invention relates to a multi-speed transmission on a central axis (6a), comprising a drive-side hollow shaft (4a) and an output-side hub sleeve (I) and two, at least two-stage, planetary gearboxes (EG, NSG), arranged coaxially therebetween or therein, each gearbox having sun gears, planetary gears which are connected to one another via associated frames, and ring gears, and each can be shifted into a direct drive and into a plurality of stepped conversion modes, wherein the first planetary gearbox (EG) is driven on its frame (8) and can be selectively shifted, by means of three clutches (20, 30, 40), into the direct drive or by axially fixing individual sun gears (9c,9d) into said transmission modes, and the second planetary gearbox (NSG) can be shifted by further clutches (50, 60, 70, 80, 90) by means of an axial fixing of the sun gear (204) when the input drive and output drive are shifted between its ring gear (200) or frame (202) into a conversion mode at a low speed and into a conversion mode at high speed and directly into a gear. By means of an axially displaceable control slide, spring-loaded, radially extending coupling rings (e.g 91a, 91b) of a respective gear stage can be released, such that the control slide is guided in helical circular grooves (24 . . . 94) of a coaxial switching drum (6b) and in radial slots that are oriented parallel to the gear axis of a hollow axle (6a) enclosing them, respectively actuating the associated coupling rings.

The invention relates to a multi-speed transmission on a central axis (6a), comprising a drive-side hollow shaft (4a) and an output-side hub sleeve (I) and two, at least two-stage, planetary gearboxes (EG, NSG), arranged coaxially therebetween or therein, each gearbox having sun gears, planetary gears which are connected to one another via associated frames, and ring gears, and each can be shifted into a direct drive and into a plurality of stepped conversion modes, wherein the first planetary gearbox (EG) is driven on its frame (8) and can be selectively shifted, by means of three clutches (20, 30, 40), into the direct drive or by axially fixing individual sun gears (9c,9d) into said transmission modes, and the second planetary gearbox (NSG) can be shifted by further clutches (50, 60, 70, 80, 90) by means of an axial fixing of the sun gear (204) when the input drive and output drive are shifted between its ring gear (200) or frame (202) into a conversion mode at a low speed and into a conversion mode at high speed and directly into a gear. By means of an axially displaceable control slide, spring-loaded, radially extending coupling rings (e.g 91a, 91b) of a respective gear stage can be released, such that the control slide is guided in helical circular grooves (24 . . . 94) of a coaxial switching drum (6b) and in radial slots that are oriented parallel to the gear axis of a hollow axle (6a) enclosing them, respectively actuating the associated coupling rings.

A roughing grinding tool has a supporting body and at least one abrasive circle. The supporting body includes an abrasive grain for roughing grinding. The supporting body serves to support the at least one abrasive circle and itself for roughing grinding. The roughing grinding tool is easy to produce and robust and has a high removal capacity in conjunction with a long service life.

A roughing grinding tool has a supporting body and at least one abrasive circle. The supporting body includes an abrasive grain for roughing grinding. The supporting body serves to support the at least one abrasive circle and itself for roughing grinding. The roughing grinding tool is easy to produce and robust and has a high removal capacity in conjunction with a long service life.

A hub assembly for a human-powered vehicle comprises a hub axle, a first rotatable member, a second rotatable member, and a rotation control structure. The rotation control structure couples the first rotatable member to the second rotatable member to transmit a first input rotation of the first rotatable member to the second rotatable member at a first ratio of a first output rotation of the second rotatable member to the first input rotation of the first rotatable member. The rotation control structure couples the second rotatable member to the first rotatable member to transmit a second input rotation of the second rotatable member to the first rotatable member at a second ratio of a second output rotation of the first rotatable member to the second input rotation of the second rotatable member. The second ratio is different from the first ratio. The second ratio is larger than 0.

A hub assembly for a human-powered vehicle comprises a hub axle, a first rotatable member, a second rotatable member, and a rotation control structure. The rotation control structure couples the first rotatable member to the second rotatable member to transmit a first input rotation of the first rotatable member to the second rotatable member at a first ratio of a first output rotation of the second rotatable member to the first input rotation of the first rotatable member. The rotation control structure couples the second rotatable member to the first rotatable member to transmit a second input rotation of the second rotatable member to the first rotatable member at a second ratio of a second output rotation of the first rotatable member to the second input rotation of the second rotatable member. The second ratio is different from the first ratio. The second ratio is larger than 0.

The invention discloses an automatic downshifting and variable speed transmission bicycle, comprising a bicycle stand, wherein the bicycle stand is installed with a bottom bracket; the bottom bracket is installed with a bottom bracket sprocket set, and the bottom bracket sprocket set is composed of three chain discs of different sizes; a rear axle of the bicycle is provided with a tower footing, and the tower footing is fixedly installed with a sun gear; one side of the sun gear is provided with a planet carrier, and the planet carrier is installed with planetary twin gears. The invention is easy to start, can run at high speed, has multiple functions, and is reliable in operation, with convenient maintenance and low cost, and is energy saving and environmental-friendly; it has a good market prospect and brings great convenience to cyclists.

The invention discloses an automatic downshifting and variable speed transmission bicycle, comprising a bicycle stand, wherein the bicycle stand is installed with a bottom bracket; the bottom bracket is installed with a bottom bracket sprocket set, and the bottom bracket sprocket set is composed of three chain discs of different sizes; a rear axle of the bicycle is provided with a tower footing, and the tower footing is fixedly installed with a sun gear; one side of the sun gear is provided with a planet carrier, and the planet carrier is installed with planetary twin gears. The invention is easy to start, can run at high speed, has multiple functions, and is reliable in operation, with convenient maintenance and low cost, and is energy saving and environmental-friendly; it has a good market prospect and brings great convenience to cyclists.