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.

The present invention relates to a toothed belt including: a back portion; a tension member embedded in the back portion in a belt longitudinal direction and including a twisted cord including a steel fiber; a plurality of belt teeth formed on an inner peripheral side of the back portion along the belt longitudinal direction; and a cover layer provided between the tension member and a belt tooth bottom formed between the belt teeth, in which the cover layer has a thickness in a range of 0.2 mm to 1.0 mm, and the back portion, the belt teeth, and the cover layer are integrally formed of a thermoplastic elastomer.

In a bevel gear pair, a first gear and a second gear are applied with tooth top modification, and a ratio of a distance from a pitch circle to a starting position of the tooth top modification to a distance from the pitch circle to a tooth top in the first gear is larger than a ratio of a distance from a pitch circle to a starting position of the tooth top modification to a distance from a pitch circle to a tooth top in the second gear. Thus, the bevel gear pair that can achieve smooth meshing is provided.

A tooth shape of the first tooth-shaped die part is formed have a constant tooth width from an upper end to a lower end and to correspond to a tooth width of a part in which a desired crowning has been produced. A tooth shape of the second tooth-shaped die part is formed to have a constant tooth width from an upper end to a lower end and to correspond to a tooth width of a central part, which is a part other than the part in which the desired crowning has been produced. A crowning forming method includes the steps of: forming a tooth shape on an outer circumference of the material by the tooth shape of the first tooth-shaped die part; and pressing the central part of the tooth shape of the material against the tooth shape of the inner circumference of the second tooth-shaped die part.

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 method of manufacturing a gear is provided. The method includes forming a plurality of gear teeth in a surface of a gear, the gear teeth having tooth faces defining tooth edges including tooth edge flanks and tooth edge top land and generating a convex contour at an edge break of at least one of the tooth edge flanks and tooth edge top land.

The invention relates mainly to a motor vehicle combustion engine starter motor comprising:a pinion body comprising splines on its external periphery,a pinion (31) having an axis (Y), the said pinion (31) being mounted with the ability to move on the pinion body comprising an internal periphery comprising splines (44) engaged with the splines of the said pinion body, the said pinion (31) comprising, on its external periphery,teeth (42) each having two tooth flanks (47) each comprising:a working flank (48), anda tooth root (49) extending from the said working flank (48) of the corresponding tooth (42), characterized in that the said tooth flank (47) comprises at least one tooth root (49) delimited by a curved portion (PC) having a variable radius of curvature.

The invention relates mainly to an assembly comprising:a combustion engine ring gear having a plurality of teeth, the said ring gear being defined by a modulus and a pressure angle,a starter comprising a pinion (31) able to engage with the said ring gear of the said combustion engine, the said pinion (31) having a plurality of teeth (42) is defined by a modulus (Mp) and a pressure angle (alpha_p), characterized in that a pinion product which is the product of the modulus (Mp) of the said pinion (31) and the cosine of the pressure angle (alpha_p) of the said pinion (31) is greater than a ring-gear product equal to the product of the modulus of the said ring gear and the cosine of the pressure angle of the said ring gear.

An object of the present invention is to provide a sprocket that mitigates the impact of tension fluctuations resulting from load torque changes, suppresses noise and vibration, ensures stable chain behavior, prevents sprocket durability loss and the generation of harmonics during rotation, along with a chain drive system. Tooth roots between adjacent teeth of the sprocket include those with a radial deviation from a root circle of a standard tooth profile, set within a predetermined numerical range corresponding to a tooth pitch. A phase variation pattern is created by changing a root radius in accordance with an angular position. The phase variation pattern has a waveform with an amplitude varied within a range of (1/7)Amax, where Amax represents a maximum amplitude. The chain drive system includes a plurality of sprockets and a chain passed over the sprockets, at least one of them being the above-described sprocket.

Each of an external tooth-bottom surface and an external bottom-side contact surface has a cross-sectional shape formed by a hypocycloid curved line. An external front-side contact surface has a cross-sectional shape formed by an epicycloid curved line. An external tooth-front surface is formed at a radial-inside position of a reference epicycloid curved line, that is, a position closer to a first pitch circle of an external gear. A possible contact between a tooth-front portion of the external gear and a tooth-front portion of an internal gear can be avoided. A connecting point between the external tooth-front surface and the external front-side contact surface is located at such a position that a contact surface length of an external tooth-contact surface is larger than twenty percent of a total tooth surface of the external gear.