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 gear includes teeth 3 to be engaged with teeth of a corresponding gear to transmit a rotational motion, in which a form (b) of a tooth root side of each tooth 3 includes: a first curved surface c which smoothly connects with a tooth surface a having an involute curve and has a profile represented by a curve which is convex in a direction opposite to the involute curve of the tooth surface a; and a second curved surface d which smoothly connects with the first curved surface c and has a profile defined by a quadratic function having a curve being convex in the same direction as that of the first curved surface c. Therefore, a stress generated on the tooth root side at the time of engagement with the teeth of the corresponding gear can be reduced, and the strength of the teeth can be increased.

A gearbox comprising an internal-external gear pair having a small tooth-difference, the internal-external gear pair comprising: an internal gear arranged about an internal gear axis and having a first number of internal gear teeth; and an external gear having an external gear axis arranged to orbit the internal gear axis and having a second number of external gear teeth, the external gear being arranged to engage with the internal gear teeth; wherein the small tooth-difference is less than a fifth of the number of internal gear teeth; and wherein the internal gear teeth and the external gear teeth have an involute shape with no profile shift, or with a profile shift below a value at which the working pressure angles of the internal-external gear pair would exceed, by more than 20%, a nominal pressure angle of the internal-external gear pair if no profile shift were applied.

An involute gear profile artifact for large gear traceable metrology includes six surfaces, including an involute gear profile cylindrical surface for parameter transfer, a datum bottom surface and a datum top surface that are symmetrically arranged on upper and lower sides, a root datum surface and a tip datum surface that are arranged in parallel on front and rear sides, and an alignment datum surface oppositely arranged relative to the involute gear profile cylindrical surface; and a distance from the root datum surface to a corresponding base circle center is a design distance D. The artifact can meet the traceability requirements of the values of the large gear. The artifact makes up for the lack of standard measuring instrument in a traceable metrology system for a large-diameter involute gear, and improves a value traceability system for the large gear with a diameter greater than 500 mm.

An involute gear profile artifact for large gear traceable metrology includes six surfaces, including an involute gear profile cylindrical surface for parameter transfer, a datum bottom surface and a datum top surface that are symmetrically arranged on upper and lower sides, a root datum surface and a tip datum surface that are arranged in parallel on front and rear sides, and an alignment datum surface oppositely arranged relative to the involute gear profile cylindrical surface; and a distance from the root datum surface to a corresponding base circle center is a design distance D. The artifact can meet the traceability requirements of the values of the large gear. The artifact makes up for the lack of standard measuring instrument in a traceable metrology system for a large-diameter involute gear, and improves a value traceability system for the large gear with a diameter greater than 500 mm.

A rotary element for a rotary transmission has a helical radial projection disposed about a rotary axis thereof, the helical radial projection having leading and trailing edges of different diameter. A helical peripheral surface between the leading and trailing edges has a radial profile which is inclined to a tangent to the envelope and preferably has an elliptic profile in a radial plane. In use with another such rotary element having a helical radial projection of opposite handedness in a rotary transmission, a point (P) of rolling contact of the helical peripheral surface with a helical peripheral surface of the other such rotary element helically traverses the helical peripheral surfaces of both rotary elements to positively transmit rotary drive between them without interdigitation of their respective helical radial projections and the associated sliding friction between them as arising in a gear transmission.

A gear structure includes two gears meshing with each other to transmit power. In one of the two gears, some of a plurality of teeth are partially missing in a tooth width direction. The other of the two gears has engaging portions that engage with the missing tooth portions at inter-teeth portions corresponding to the partially missing teeth among a plurality of inter-teeth portions.

A tooth for a toothed torque transmission assembly includes a tooth flank designed for torque exchange with a counter flank of a meshing partner. The tooth flank includes a periodically extending tooth flank correction including a sinusoidal corrugation having a locally extending period length T, wherein a development of the sinusoidal corrugation of the periodically extending tooth flank correction defines a center line. The periodic tooth flank correction is overlaid with a spatial microstructure having a local maxima and/or a local minima and a shortest distance t of t<T/2 between the local maxima and/or the local minima with respect to the center line. A formation of the microstructure is dimensioned to generate additional structure-borne sound in running operation of the torque transmission assembly to mask a tonality in the emitted structure-borne sound.

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.