The knuckle is the hinge on which the wheel turns, usually in a fork shape. The upper and lower forks have two coaxial holes for mounting the kingpin, and the steering knuckle journal for mounting the wheels. 
The two lugs of the pinhole on the steering knuckle are connected with the fist part at both ends of the front axle through the kingpin, so that the front wheel can deflect around the kingpin to make the car turn.
To reduce wear, a bronze bushing is pressed into the knuckle pin hole and lubricated with grease injected by a nozzle mounted on the knuckle. To make the steering flexible, a bearing is arranged between
the steering knuckle and the fist part of the front axle. An adjusting gasket is arranged between the upper ear of the knuckle and the fist part to adjust the gap.