The car's outer ball joint (outer ball joint) and inner ball joint (inner ball joint) are equivalent to the front axle and steering knuckle.
The ball head only has a ball head and a steel bowl. The steel bowl is divided into an inner steel bowl and an outer steel bowl.
The inner ball is fixed on the front axle, and the outer ball is sleeved on the inner ball and can be rotated back and forth. The outer ball is equipped with a hub. When the directional rod is pulled forward and backward, the car can turn. The driving half shaft transmits driving force to the hub through the hollow of the inner and outer ball cymbals. In order to rotate the outer ball ，, the half shaft is provided with a universal joint at the joint of the inner and outer ball cymbals so that the driving force is transmitted to the hub when the outer ball 外 is rotated.
It is necessary for the drive axle to be able to make the car turn actively.
