Why are the rear wheel cambers of the car mostly designed to be negative, and the front wheel camber angle is also small?
For the traditional design idea, the camber angle is set to control the weight of the tire body to adapt to the change of the vehicle load, reduce the partial wear of the tire, and reduce the load of the hub fastening nut to prevent the nut from slipping.Flying out and causing an accident. This is necessary for large vehicles.
For cars, the load is relatively small and the change is small, and the speed is getting higher and higher. In this way, it is more important to solve the problem of uneven wear and handling stability caused by high-speed driving.
At high speeds, the car has a large inertial centrifugal force, and even if the suspension has a stabilizer bar, the body will naturally tilt to the outside. Therefore, a vehicle having a positive camber angle at rest is cambered during steering the angle is larger, causing the lateral angle of the outer wheel to be much larger than that of the inner wheel, and the actual steering angle of the inner and outer wheels is larger than the steering angle of the pure rolling, thereby causing different degrees of side slip of the inner and outer wheels. This kind of drag the state not only increases the abnormal wear of the tire, but also reduces the adhesion of the tire to the ground, reducing the lateral stability of the vehicle body.
Based on the above considerations, the Car wheel alignment has a negative camber angle, that is, the wheel is inclined inward in a stationary state, and the wheel camber angle tends to zero when steering, thereby reducing wear during steering and improving lateral stability during steering. Prevents “exciting” and dangerous automatic steering when driving at high speeds.
Why do some front wheels of the car have a positive foreline to match the negative toe, and the rear wheel with a negative camber can be used with the front toe?
This is typically the case when the front engine is driven by the front wheels and the rear wheels are also independent suspensions.
Under the action of the front wheel traction torque, due to the gap and elastic deformation of the steering rod, the front end of the front wheel has a rolling inward around the kingpin. Therefore, the toe value of this type of vehicle is relatively small, and some even the negative toe, to give the front wheel a just correct amount of correction.
The rear wheel acts as a driven wheel, and it must overcome the effect of the rolling resistance of the rear wheel. Because of the gap and elastic deformation of the rear axle, the rear axle will have a certain bending, so that the rear wheel has a pre-tension phenomenon, so the rear of the vehicle the toe angles are mostly positive, giving the rear wheels an appropriate correction, even if the rear wheel camber is negative.
Oct-30-2018
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