A system for stopping rotation of a first gear and a second gear on a shaft, The first gear and second gear are concentric and rotatable about said shaft. The first gear and the second gear are driven by the same input system and the first gear and the second gear are configured to rotate at differential speeds and independently to each other. The first gear comprises a first end stop and the second gear comprises a second end stop and the first end stop and the second end stop are configured to engage each other when the first gear and the second gear have each rotated a predetermined number of turns. Engagement of the first end stop with the second end stop is configured to prevent rotation of the first gear and the second gear and cause a stall in the system.

A system for stopping rotation of a first gear and a second gear on a shaft, The first gear and second gear are concentric and rotatable about said shaft. The first gear and the second gear are driven by the same input system and the first gear and the second gear are configured to rotate at differential speeds and independently to each other. The first gear comprises a first end stop and the second gear comprises a second end stop and the first end stop and the second end stop are configured to engage each other when the first gear and the second gear have each rotated a predetermined number of turns. Engagement of the first end stop with the second end stop is configured to prevent rotation of the first gear and the second gear and cause a stall in the system.

The present invention is directed to a self-locking non-backdrivable gear system. The gear system may comprise a primary motor input and gear box. The primary motor input is for rotation of the gearbox about the axis of a drive shaft. The gearbox may comprise an input ring gear, one or more locking gears, fixed gear, and output gear. In operation, rotation of the primary motor input causes rotation of the ring gear which causes rotation of the locking gear which causes rotation of the output gear which causes rotation of the drive shaft. However, in the absence of rotation of the ring gear, a rotational force applied to the output gear causes the gear teeth on the fixed and output gears to lock the gear in place.

The present invention is directed to a self-locking non-backdrivable gear system. The gear system may comprise a primary motor input and gear box. The primary motor input is for rotation of the gearbox about the axis of a drive shaft. The gearbox may comprise an input ring gear, one or more locking gears, fixed gear, and output gear. In operation, rotation of the primary motor input causes rotation of the ring gear which causes rotation of the locking gear which causes rotation of the output gear which causes rotation of the drive shaft. However, in the absence of rotation of the ring gear, a rotational force applied to the output gear causes the gear teeth on the fixed and output gears to lock the gear in place.

A harmonic drive comprises a wave generator, a resilient, geared transmission element that can be deformed by the wave generator, a connecting element on the housing side, and a connecting element on the output side. The resilient transmission element has two different tooth systems, a spline tooth system and a running tooth system; the spline tooth system is coupled along the entire circumference to one of the connecting elements for conjoint rotation therewith, and the running tooth system is provided for cooperation with the wave generator and partial engagement in a mating running tooth system on the other connecting element.

The invention relates to a bicycle gearing, comprising: a cylindrical-gear gearing (10), which has a stationary sun gear (11) having a central bearing axis (y.sub.1) extending centrally therein and a planet gear (12), which travels on the sun gear (11) and rotates about a planet-gear bearing axis (y.sub.2); a four-bar linkage (20), which interacts with the cylindrical-gear gearing (10) and which comprises a crank (21), which is fixedly connected to the planet gear (12) and is rotatably connected to a pedal crank (22); and a toothed wheel (30), by means of which a traction means (31) can be driven. The problem addressed by the invention is that of improving a bicycle gearing of the type in question in such a way that a rounder pedaling feel is perceived by the bicycle rider. The problem is solved according to the invention in that the toothed wheel (30) has an oval shape.

The invention relates to a bicycle gearing, comprising: a cylindrical-gear gearing (10), which has a stationary sun gear (11) having a central bearing axis (y.sub.1) extending centrally therein and a planet gear (12), which travels on the sun gear (11) and rotates about a planet-gear bearing axis (y.sub.2); a four-bar linkage (20), which interacts with the cylindrical-gear gearing (10) and which comprises a crank (21), which is fixedly connected to the planet gear (12) and is rotatably connected to a pedal crank (22); and a toothed wheel (30), by means of which a traction means (31) can be driven. The problem addressed by the invention is that of improving a bicycle gearing of the type in question in such a way that a rounder pedaling feel is perceived by the bicycle rider. The problem is solved according to the invention in that the toothed wheel (30) has an oval shape.

A strain wave gearing has a rigid internally toothed gear, a flexible externally toothed gear, and a wave generator. Before being flexed by the wave generator, the externally toothed gear has a cylindrical body part, an inside diameter of which is such that the inside diameter D is smallest at a rear end thereof and increases gradually from the rear end to an opening end thereof. After being flexed by the wave generator, D1D is satisfied where D1 is the minor diameter of an elliptical inner circumferential surface of the opening end of the cylindrical body part. The externally toothed gear, which is provided with such a tapered cylindrical body part, is suitable for manufacturing by die molding such as casting, and can also alleviate excessive uneven contact thereof with a wave bearing.

A self-locking nut and screw assembly may include a screw and a first nut rotatable and linearly translatable with respect to each other. The assembly may also include a first motor configured to provide torque to one of the screw and the first nut. The assembly may further include a locking mechanism configured to lock the screw to prevent backdrive when the motor is not providing torque to the one of the screw and the first nut.

A lifter device includes: a pinion gear; a rotation control device including: a rotation shaft rotating in synchronization with the pinion gear; a support member supporting the rotation shaft; a rotation drive mechanism configured to rotate the rotation shaft; and a lock mechanism configured to lock rotation of the rotation shaft when an operation handle is in an operation-released state and including: a first tooth; and a second tooth configured to selectively mesh with the first tooth to lock relative rotation of the rotation shaft and the support member; and a speed increasing mechanism provided closer to the rotation shaft than a meshing portion of the first tooth and the second tooth in a rotation transmission path, configured to transmit the rotation of the rotation shaft to one of the first tooth and the second tooth, and configured to speed up the transmitted rotation of the rotation shaft.