Ntn Corporation

Masanori Satou

Katsufumi Abe

Yoshiyasu Nakano

Provided are a gear in which oil film formation between the tooth surfaces of gears rotating at high speed can be effected to a sufficient degree, in which generation of pitting, abrasion, and scoring is prevented, and which helps to prevent an increase in temperature and wear to achieve an improvement in durability, and a gear drive unit. A multitude of minute concave recesses are provided at random on a tooth surface, and an average area of the recesses is set to a range of 160 to 740 &#x3bc;m. Accordingly, the tooth surface can obtain a high oil film forming capacity. Thus, even under a low-viscosity/thin-lubrication condition in which the thickness of the oil film is extremely small, it is possible to achieve a long service life.

Gear and gear drive unit

Provided are a gear and a gear drive unit which allow oil film formation to a sufficient degree between tooth surfaces of gears rotating at high-speed and which help to prevent generation of pitting, abrasion, and prevent scoring, temperature rise, and wear to thereby achieve an improvement in terms of durability. A tooth surface is provided with a multitude of minute recesses arranged at random, in which an axial surface roughness parameter Ryni of the surface thus provided with the recesses is set to a range: 0.8 &#x3bc;m&#x2266;Ryni&#x2266;2.3 &#x3bc;m. As a result, the tooth surface is endowed with a high oil film formation performance, and it is possible to attain a long service life even under a low-viscosity/thin-lubrication condition in which the oil film is extremely thin.

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Iwata, Japan

Masanori Satou