The King Pin serves as the main pivot in the steering mechanism of a vehicle, connecting the steer axle to the steering knuckle.

It supports the steering geometry and allows the wheel ends to turn the vehicle smoothly. These sturdy steel pins, in conjunction with the bushings, handle substantial forces while ensuring proper alignment of the knuckle. Additionally, the King Pin plays a crucial role in the steering and handling of the coupled rig, working in partnership with the larger fifth wheel.

The King Pin angle aids in steering by encouraging the wheel to return to the straight-ahead or center position, leveraging the vehicle's weight to rotate the wheel about the King Pin.