Patent 7942586 was granted and assigned to NTN Corporation on May, 2011 by the United States Patent and Trademark Office.
In a thrust needle bearing employing lubricating oil and having rollers held by a cage and rolling on races, the value of the arithmetic average roughness Ra of roller is 0.03 to 0.15 μm. Even when the bearing is used under the conditions where lubrication is lean or lubrication characteristics are wrong, the rolls can be prevented from being worn at the contact parts thereof with the pocket guide face of the cage and the life of the rollers and races can be increased.