Constant velocity (CV) joints are used in automobiles where an independent suspension is used. They allow the suspension to travel up and down while maintaining the same rotational velocity at the wheel as at the input to the axle or driveshaft. The main area of friction is at the roller-housing interface which consists of an oscillating interaction. Other areas of friction include the needle-spider and needle-roller interfaces. To reduce friction and wear in these areas, specialized CV joint grease is applied. Click on the image below for an animation. Again, the red denotes areas of high friction.
Click on the image to see the animation.