Main angles of automotive four-wheel alignment:
Camber angle
Definition: Looking from the front of the car, the angle formed by the centerline of the tire and the vertical plumb line to the ground is called the camber angle. It is stipulated that the outward inclination of the wheel is positive, and the inward inclination of the wheel is negative.
Function: Prevent the wheels from inclining inward due to suspension deformation when the vehicle is fully loaded, avoid uneven tire wear and reduce the load on the hub bearings. Reduce the distance from the grounding point of the longitudinal rotating plane of the front wheel to the intersection of the extension line of the kingpin centerline and the ground, thus making steering easier.
Kingpin inclination angle
Definition: Looking from the front of the car, the angle formed by the steering axis centerline and the vertical plumb line to the ground is called the kingpin inclination angle. It is stipulated that the inward inclination of the kingpin is positive, and the outward inclination of the kingpin is negative.
Function: Make steering easier and also generate a return torque for the front wheels after steering.
Caster angle
Definition: Looking from the side of the car, the angle formed by the steering axis centerline and the vertical plumb line to the ground is called the caster angle. It is stipulated that the backward inclination of the kingpin is positive, and the forward inclination of the kingpin is negative.
Function: When the steering wheel is slightly deflected by accidental external forces during driving, the caster angle will generate a torque in the opposite direction of wheel steering to make the wheels return automatically, which can ensure the stability of the car's straight-line driving.
Toe angle
Definition: Looking down from directly above the car, the angle between the centerline of the tire and the longitudinal geometric centerline of the car is called the toe angle. It is stipulated that when the distance between the front edges of the two wheels is less than the distance between the rear edges, it is positive, and vice versa. The angle between the centerlines of the two tires is called the total toe angle.
Function: Eliminate the adverse consequences caused by camber angle, reduce the pressure on hub bearings and tire wear.
Other angles
Thrust angle: The bisector of the total toe angle of the rear wheels is called the thrust line. The angle formed between the geometric centerline of the vehicle body and the thrust line is called the thrust angle. The positive and negative signs of the thrust angle are stipulated as follows: when the thrust line is deflected to the left, the thrust angle is positive, and vice versa.
Turning toe-out on turns: The difference in the turning angles of the two front wheels when the vehicle is turning is called the turning toe-out on turns. Usually, the turning toe-out on turns when steering at 20° is used as the measured value.
Included angle: Looking from the front of the car, the angle between the kingpin axis and the centerline of the wheel tire is called the included angle. Numerically, it is equal to the sum of the kingpin inclination angle and the camber angle.
