The parameters for four-wheel alignment include front wheel toe-in, wheel camber angle, kingpin inclination angle, and kingpin caster angle. Each of these angles has a factory value, a maximum value, and a minimum value. If the detected data falls within the range from the minimum to the maximum value, the parameter is considered normal. Typically, a green display on the alignment machine indicates normal, while red indicates abnormal.
Front Wheel Toe-In
Due to the wheel's camber, the left and right wheels often exert opposite side forces related to the camber angle, increasing tire wear. To avoid this, the side force must be eliminated. This can be achieved by setting the wheels so that the front edges of the two front wheels are closer together than the rear edges, which is known as front wheel toe-in.
The purpose of toe-in is to ensure that when the steering wheel encounters external force and causes deflection, it can automatically return to the straight-ahead position once the external force disappears, meaning it can self-correct. Toe-in also counteracts the adverse effects of wheel camber, allowing the wheels to roll straight without lateral sliding, thereby reducing tire wear.
Wheel Camber Angle
Wheel camber angle refers to the angle between the wheel's centerline and the vertical line. When the wheel is installed and its top leans outward, causing the tires to form a "V" shape, it is called positive camber. When the top of the wheel leans inward, forming an inverted "V" shape, it is called negative camber. Negative camber helps prevent tire skidding during turns and increases steering resistance, while positive camber affects the vehicle's straight-line stability and the ability of the steering wheel to return to center.
Kingpin Inclination Angle
The kingpin inclination angle is the acute angle formed between the steering knuckle's kingpin axis and the vertical line, as projected onto a plane perpendicular to the vehicle's longitudinal centerline. This angle helps to make steering easier and reduces the impact forces transmitted from the steering wheels to the steering wheel.
Kingpin Caster Angle
The kingpin caster angle refers to the angle between the kingpin axis and the vertical line when the kingpin is tilted backward in the longitudinal plane. This angle maintains the vehicle's straight-line stability and helps the front wheels automatically return to the straight-ahead position after turning.
