Modern automotive steering and suspension system is solid geometry in engineering practice is one of the examples of successful application. Wheel alignment integration of steering and suspension system all the geometric parameters, in order to obtain a safe handling, ride comfort and the long service life of the tire.
Front wheel alignment meaning is defined by the steering and suspension parts of the angle formed between the. In general, auto repair industry need to check the front wheel alignment of the 5 parameters: the caster, wheel camber, toe-in, wheel steering shaft angle and turning angle ( turning the front wheel beam ). If in addition to the front wheel alignment, but also for the four wheel alignment, we must also be delayed ( lag angle turn ) and motor thrust angle consideration. Therefore, in the four round of alignment, must also check the car rear wheel camber and the rear wheel before the beam.
Tire wear and direction control
Wheel camber, toe-in angle and turning the wheel camber angle itself can cause tire wear.
If the location parameter setting is not correct, tire wear is not balanced, but also to wear more quickly than normal. Because the camber and the steering axis angle, therefore, the steering axis angle, and tire wear related. Kingpin caster angle and delay ( lag angle turn ) is generally not increased tire wear, unless they are severely deviates from the specification value. All of the alignment angle is the direction control angle, that is to say, they are able to influence the vehicle steering characteristics and direction of controllability.
In the solution of vehicle handling, ride comfort and vibration problems before, we must first understand each wheel alignment angle significance, as well as all wheel alignment angle is to work together. On the systematic diagnosis work before, we all should know about the working principle of the system.
Caster
Caster is defined from the side of the car at each front wheel steering axis inclination, degree of tilt is used to measure the tilt angle. If the steering axis inclination, namely the upper ball joint or strut mounting points at the lower end of the spherical joint behind, after angle is positive; if the steering axis tilt forward, then the tilt angle is negative. The rear wheels do not have detection angle.
Caster effect of automobile straight driving stability and steering wheel return function. After dip angle is bigger, the front wheels are in a straight line trend. On one hand, if the positive rake angle size is proper, can ensure the vehicle driving stability, but also so that the steering wheel in steering to return; on the other hand, is after the dip increased steering resistance. Therefore, if a car equipped with power steering, the allowed by the posterior tilt than the manual steering system in many.
Kingpin caster angle is too small will cause the instability of steering wheel, and the shaking. In extreme cases, negative rake angle and the consequent wheel sloshing will aggravate the Goblet of front wheel wear. If the caster or unequal, cars will be pulled to the right after a small angle ( or greater negative caster angle of the side ). In the solution of vehicle driving deviation problems, with particular attention to this point.
Extraversion
Camber is defined from the front of the car watching the wheels off the plumb line, with backward, decumbent with camber angle measurement ( as shown in Figure 2. ). If the tyre top inclined outwards, then the camber is positive; if the tyre top inclined inwards, camber is negative.
Zero camber refers to the wheel and tire is perpendicular to the ground, the tire wear minimal. Positive camber angle so that the tread of a tire tread wear than in faster; negative camber opposite. Smaller camber contribute to steering and steering, with technical specifications of camber on tire wear almost have no effect, but too big camber can cause tire wear is increased, thereby shortening the service life of the tyre.
Positive camber as positive rake angle as the car straight driving stability and steering wheel return function. When the vehicle is turning, due to the positive camber angle, lateral suspension to lift off the wheels of the trend, when the car back to the straight direction, vehicle weight on the steering shaft, the wheel is back to help. Negative camber in turn prevent tire side slip, but also increase the steering resistance. The majority of passenger cars and light trucks are designed as a positive camber, but many racing and high-performance city car uses negative camber.
The rear wheels generally use the zero camber, but some independent rear suspension design has a certain degree of camber (usually negative ). If camber % per month, car is pulled to having positive camber angle larger side; rear wheel camber is not equal to also affect the car control.
Therefore, in the four wheel alignment, must pay attention to these questions.
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