one universal joint has four needle roller bearings that provide the strength and life which is most important and both the axes of the spider are inserted into two yokes. In the bearing, a seal is located to prevent dust, water, etc.from ingress and to prevent grease egress. For heavy duty vehicles with high torque transmission, such as large size vehicles and various industrial machine vehicles, a wing type (3 kinds: block, wing, delta) is used. Bolt-fastening mechanism and key-way are incorporated to the bearing and a precise circle is on its back. By receiving the torque through the key-way, even if a bolt is loosely tightened, the shearing stress does not apply to the bolt.