2. Excessive inclination of the kingpin will slow down the steering response, and the front and rear bumps of the wheels will be aggravated by road interference. The greater the inclination angle, the more sensitive the steering.
1, caster angle, when the wheel is viewed from the side, the steering kingpin (the center of rotation when the wheel rotates) falls backwards, which is called caster angle. After the caster angle of the kingpin is set, the distance between the center line grounding point of the kingpin and the ground projection point of the wheel center (called kingpin pitch, which is the same as the principle that the front wheel fork beam of the bicycle leans backwards) is generated, so that the wheel grounding point is located at the back end of the extension line of the steering kingpin, and the wheel is pulled backwards through rolling resistance during driving, so that the wheel direction naturally faces the driving direction. Setting a large caster angle of the kingpin can improve the straight running performance, and at the same time, the pitch of the kingpin also increases. Excessive pitch of the kingpin will make the steering wheel heavy, and the front and rear bumps of the wheels will be aggravated by road interference;
2. kingpin inclination: when the tire is viewed from the front and rear direction of the vehicle, the kingpin axis inclines to the inside of the vehicle body, which is called kingpin inclination. When the wheel rotates around the kingpin, the lowest point of the wheel will fall below the road surface, but in fact, the lower edge of the wheel cannot fall below the road surface, but the steering wheel and the whole front will be raised by a corresponding height, so that the gravity of the car itself will restore the steering wheel to its original middle position, so the steering wheel is easy to reset;
3. Front wheel camber. When the wheel is seen from the front and rear direction, the tire is not installed vertically, but slightly inclined and splayed in a figure of eight, which is called negative camber, and when it is spread in the opposite direction, it is called positive camber. In the heyday when diagonal tires were used, the camber angle was set to be relatively large because the tires touched the ground obliquely, which was convenient for the operation of the steering wheel. Cars generally set the camber angle very small, close to vertical. Flat radial tires for automobiles are becoming more and more popular. Due to the characteristics of radial tire (high tread rigidity and wide tread), if camber is set, the tire will be eccentric and the tire friction will be reduced. Due to the continuous use of power steering mechanism, camber angle is also shrinking. Nevertheless, setting a small camber angle can exert appropriate lateral thrust on the wheel bearing on the axle;
4, the front wheel toe-in, four-wheel positioning toe-in, the so-called "inner splayed foot" means that the left and right front wheels are inward respectively. The purpose of adopting this structure is to correct the outward rotation of the wheel caused by the camber angle of the front wheel. As mentioned earlier, steering wheel operation becomes easy due to camber angle. On the other hand, because the wheels are inclined, the left and right front wheels rotate outward respectively. In order to correct this problem, if the left and right wheels have inward angles, plus or MINUS zero, the left and right wheels can keep moving in a straight line and reduce tire wear.