| 摘要 |
The present invention relates to a pulley which is brought into contact with a timing belt of an engine of automobile and a belt for driving auxiliary machinery, and a ball bearing used for the same, wherein the radial internal clearance in the running state of a ball bearing is set to substantially 5 to 30.mu.m, and grease to be sealed in said ball bearing is such that the base oil thereof is made a mixture of .alpha. -olefin oligomer and ester, the thickening agent thereof is made a mixture of an alicyclic urea compound and an aliphatic urea compound. the worked penetration thereof is roughly 240, and the base oil viscosity thereof is made 40 to 43cSt at a temperature of 40 .degree. C, whereby it is possible to suppress self-excited vibrations of a rolling element and to securely prevent the hoot sound from occurring. Furthermore, since grease used herein has superior characteristics in the high temperature durability, there is no worry about a lowering of the high temperature durability as in conventional pulleys in which low temperature grease of good low temperature characteristics is employed. |
