Note: Only the toe-in of the front and rear wheels can be adjusted.
1. The geometry of the suspension and its rigidity determine the possibility of limiting the vertical movements of the body and reducing angular vibrations around the transverse and longitudinal axes.
2. The front wheels rotate around inclined axles, whose position is determined by the hinges and suspension parts of the car.
3. The most important are the following kinematic settings of the wheel assemblies in relation to steering and the transmission of forces between the tires and the road surface. Wheel alignment angles have a significant impact on vehicle stability, tire wear and fuel consumption. The nominal values of the wheel alignment angles subject to inspection and adjustment for the vehicles considered in this Manual are given in Specifications at the beginning of the chapter.
4. Convergence (convergence) is called the angle between the lines formed by the intersection of the horizontal plane of the planes of the wheel assemblies of one axle of the vehicle; toe-in can also be defined as the difference in distances between the front and rear flanges of the wheel rims (see illustration). Toe-in affects the straightness of the vehicle's movement and its controllability, and on front-wheel drive models it compensates for the resulting kinematic changes in the suspension geometry determined by the effect of traction force. At zero toe-in, the distance between the front edges of the wheels is equal to the distance between their rear edges.
5. Collapse (see illustration) is called the angle between the lines formed by the intersection of the following three planes:
- a vertical plane drawn through the centers of the wheel assemblies of one axle of a vehicle;
- plane of symmetry of the car;
- wheel disk plane.
If the top of the wheel is tilted toward the axis of symmetry of the car, the camber is called negative, and vice versa. Correct camber adjustment determines the size and position of the contact patch of the treads with the road surface and allows for compensation of changes in the suspension geometry that occur during turns and when the car is moving on an uneven road surface.
6. The kinematic length of the journal is the shortest distance between the center of the steering wheel and its axis of rotation (see illustration 23.5).
7. The stabilization shoulder is the distance between the point of contact of the wheel and the point of intersection of its axis of rotation with the road surface in the side view (see illustration 23.5), which determines the magnitude of the stabilizing moment and affects the directional stability of the vehicle and the distribution of forces in the steering when making turns.
8. The coast is the angle of longitudinal inclination of the wheel's rotation axis, i.e., the angle between the rotation axis and the vertical in the side view (see illustration 23.5). Together with the lateral tilt angle of the axle (see below), the coasting affects the change in wheel camber when measuring the steering wheel angle, as well as the stabilizing moment.
9. The rolling shoulder is defined as the distance between the point of contact of the wheel with the road surface and the point of intersection of its turning axis with the road surface in the front view (see illustration 23.5). The shoulder is considered negative when the last of the above-mentioned points is between the center and the top of the wheel. The parameter affects the degree of impact of braking forces on the steering wheel and the magnitude of the stabilizing moment, and a negative running shoulder increases the latter.
10. The angle of the transverse inclination of the wheel rotation axis is the angle between the wheel rotation axis and the vertical in the plane of the vehicle's cross section (see illustration 23.5). Along with the coasting (see above) and the magnitude of the longitudinal displacement of the pivot axis (see ibid) affects the sensitivity of the steering.