A resin molding mold, by which a resin worm wheel for a worm speed reducer is molded, includes a plurality of tooth forming portions provided such that the tooth forming portions are disposed at predetermined intervals on a circumference of the resin molding mold. The tooth forming portions each include a projection portion provided in a part of a tooth-flank forming surface by which a tooth flank is formed.

A torque transmission apparatus having a shift collar and a drive component. The shift collar may have a collar gear that may have a collar tooth that may have a concave collar tooth side surface that may be centered about a transverse collar tooth plane. The drive component may have a tooth that may have a convex lateral side surface centered about a transverse tooth plane. The concave collar tooth side surface may cooperate with the convex lateral side surface to align the transverse collar tooth plane with the transverse tooth plane.

A thickened robot joint transmission structure comprises a shell, dual gear rings and a planet carrier, wherein the planet carrier is fixed to the shell through a crossed roller bearing. Planet gears are dual thickened planet gears free of a sun gear. The input ends are a pair of gears or spiral bevel gears with a variable velocity ratio and are fixed to the shell through deep groove ball bearings. The dual thickened planet gears serve as a hollow for a cable, a related shaft or a line object to pass through after the sun gear is removed.

A gear for transmitting power has a plurality of teeth, each having two tooth flanks for transmitting power to another gear. The gear can be rotated about an axis of rotation, and has a reference plane, which is arranged orthogonal to the axis of rotation. Tooth flanks of the same name are the tooth flanks for transmitting power in one direction of rotation, wherein the tooth flanks have a tooth flank length proceeding from a front side of the reference plane. Two tooth flanks of the same name are arranged directly adjacent to a crown tooth flank, said two tooth flanks of the same name each having a smaller tooth flank length than the crown tooth flank. The gear has at least one of the crown tooth flanks and is configured as a helically toothed gear.

A reduction gear W1 that is configured to reduce a rotation speed input to an input shaft 1, and output the reduced rotation speed from an output shaft, the reduction gear including: an inner trochoid 8 that has a wavy curved surface formed on an inner circumferential side surface thereof; an inner trochoid holder 9 that is designed to hold the inner trochoid 8; an outer trochoid 3 that has a wavy curved surface formed on an outer circumferential side surface thereof; a rotation restriction unit that is designed to restrict rotation of the outer trochoid 3 around an axis thereof; and an output pin 9 that is pinched between the outer circumferential side surface of the outer trochoid 3 and the inner circumferential side surface of the inner trochoid 8.

A gear tooth for a gear of a planetary gear device may include a profile modification that alters a profile of the gear tooth to reduce wear and noise. Aspects of the profile modification may include a planar surface that connects a tip surface of the gear tooth with a first or second side of the gear tooth. Other aspects of the profile modification may include a curved surface connecting a tip surface of the gear tooth with a first or second side of the gear tooth. The gear tooth may also include non-constant profile width as measured between the first side and the second side in a gear thickness direction extending between the top and bottom surfaces of the gear. Aspects of gear teeth with either or both the profile modification and non-constant profile width may reduce tooth wear and gear noise during operation of the planetary gear device.

A torque transfer device has plural planets arranged for planetary rotation about one or more sun gears and within one or more ring gears. Each planet includes at least one planetary gear set comprising plural planetary gears connected to rotate together, but having a different diameter to form a differential gear system. To improve load sharing, the plural planetary gears of each planetary gear set may have a different helical angle, the plural planetary gear sets being axially movable with respect to one another. Alternatively or in addition, the planetary gears may be made flexible with respect to radial forces.

A torque transfer device has plural planets arranged for planetary rotation about one or more sun gears and within one or more ring gears. Each planet includes at least one planetary gear set comprising plural planetary gears connected to rotate together, but having a different diameter to form a differential gear system. To improve load sharing, the plural planetary gears of each planetary gear set may have a different helical angle, the plural planetary gear sets being axially movable with respect to one another. Alternatively or in addition, the planetary gears may be made flexible with respect to radial forces.

A plastic helical gear has a three-dimensional tooth surface modification section on a tooth surface of each of involute-shaped teeth. The three-dimensional tooth surface modification section is a combined surface of a tooth top modification surface and an arc crowning surface. The tooth top modification surface is reduced in tooth thickness from a position between a tooth top and a tooth root toward the tooth top. The arc crowning surface is reduced in tooth thickness from a position between one end in the tooth width direction and the other end in the tooth width direction toward both ends in the tooth width direction. A line extending from an intersection point P0 between the starting position of the tooth top modification surface and the apex position of the arc crowning surface to the tooth root is aligned with a line on the tooth surface of the involute-shaped tooth.

An assembly for acoustically influencing toothed wheels, including at least one first toothed wheel having teeth and one second toothed wheel having teeth, wherein the teeth have flanks, wherein at least one flank of a tooth of the first toothed wheel can be engaged with a flank of a tooth of the second toothed wheel, wherein at least one flank of a tooth of the first toothed wheel forms a contact zone or, in the ideal case, a contact line with an engaging flank of a tooth of a second toothed wheel, wherein the contact zone or the contact line is formed at an angle .sub.Aq, in particular between 5 and 85 or between 95 and 175, in relation to an axis of an undulation, a microangle distribution, and/or a microangle periodicity of the engaging flank of the tooth of the second toothed wheel.