A pressure angle of the worm is set to be greater than a pressure angle of the worm wheel so that a maximum number of meshing teeth becomes smaller than or equal to n (where n is a natural number) with respect to the speed reduction mechanism in which a number of meshing teeth is always n+1 or changed between n+1 and n by rotation under a condition in which the pressure angles of the worm and the worm wheel are the same with respect to each other.

A gear assembly that can prevent a reduction in power transmission efficiency and a manufacturing method thereof are provided. The gear assembly comprises a first gear and a second gear. The gear assembly is designed in such a manner that first gear tooth and the second gear tooth are contacted properly to each other in a plane of action when operated in a predetermined condition. A rigidity reducing portion is formed on a first base portion to avoid improper contact in the plane of action when the gear assembly is operated in a different condition.

A power transmission device includes coaxially a first rotary body including a first gear on a drive source side, a second rotary body including a second gear on a driven side, a third rotary body including a third gear movably held to transmit a driving force, and a guide member disposed at one of the first gear, the second gear, and the third gear to contact a first end surface of a gear tooth of another of the first gear, the second gear, and the third gear, serving as a mating gear, to guide the first end surface between teeth of the one of the first gear, the second gear, and the third gear. The guide member extends toward the mating gear and a tip of the guide member is placed at a distance from an end of the one of the gears in the axial direction.

A gear of a gear device includes a plurality of teeth having tooth surfaces. The tooth surfaces are shaped such that contact length ratios of three or more of the teeth are outside a predetermined range centered on an average value of the contact length ratios of all of the teeth, where the contact length ratio is obtained by dividing a contact length of a tooth contact face by a diagonal length of a plane of action.

A gearbox assembly includes a first gear and a second gear. The first gear includes a plurality of first gear teeth. The second gear includes a plurality of second gear teeth. The plurality of first gear teeth and the plurality of second gear teeth mesh with each other as the first gear and the second gear rotate. A profile shape of at least one first gear tooth of the first gear is characterized by a total profile modification between 66 micrometers and 120 micrometers.

A gearbox (1), in particular coaxial gearbox, includes a ring gear having an internal toothing (3); a tooth carrier (5) having guides (7) which are aligned radially in terms of a rotation axis of the gearbox; teeth (9) which, for engaging with the internal toothing (3), are received in the guides (7), wherein the teeth (9) are mounted in the guides (7) displaceable in the direction of their longitudinal axis (11) relative to the tooth carrier (5); and a cam disk (13) which is rotatable about the rotation axis and is operatively connected to the teeth (9); wherein the teeth (9) have in each case a tooth flank (17) which is at least partially curved along a width curve (51) extending over a width (41) of the tooth flank (17).

A flat gearing in the form of a strain wave gearing includes a circular spline having an inner toothing; a dynamic spline which is axially adjacent to the circular spline and has an inner toothing; a flexible flexspline which is arranged inside the circular spline and dynamic spline and has at least one outer toothing; and a wave generator which is arranged inside the flexspline for deforming the flexspline in the radial direction. An interlocking, torque-transmitting connection is established between the circular spline and the flexspline at two opposing points on the flexspline and between the flexspline and the dynamic spline at four positions on either side of the contact with the circular spline. The axial course of the radial position of the tooth transverse of the at least one outer toothing of the flexspline has a region which is reduced radially in the direction of a center axis of the flat gearing.

A rolling gear rack mechanism with tooth profile having hyperbolic tooth line structure based on a parabolic function includes a gear and a rack. An end face tooth profile of the gear and an end face tooth profile of the rack are composed of an end face working tooth profile curve and a tooth root transition curve, and the end face tooth profile of the gear and the end face tooth profile of rack are both symmetrical left and right. The end face working tooth profile curve of the gear and the end face working tooth profile curve of the rack are parabolic, and a tooth surface of the gear and a tooth surface of the rack have a hyperbolic tooth line structure. At least one pair of gear teeth meshing points of the gear and the rack are located at nodes to achieve rolling meshing contact.