12.5.10. The angles of installation of wheels of the car - the general information
Only convergence of forward wheels is subject to adjustment.
The possibility of restriction of vertical movements of a body and reduction of angular fluctuations around cross and longitudinal axes is defined by geometry of a suspension bracket and its rigidity.
Forward wheels turn around inclined axes whose situation is defined by hinges and details of a suspension bracket of the car.
Is the most important the listed below kinematic installations of wheel assemblies in relation to steering and transfer of forces between tires and a paving. The angles of installation of wheels considerably influence stability of the car, wear of tires and fuel consumption. Nominal rates the subject check and adjustment of angles of installation of wheels of the cars considered in the present manual are specified in Specifications at the beginning of the Head Podvesk and steering.
Convergence (convergence) is called the projection to the horizontal plane of a corner between the plane of symmetry of the car and the plane of the wheel assembly passing through the center of the tire of the operated wheel; difference of distances between forward and back boards of rims of wheels can be also defined. Convergence exerts impact on straightforwardness of the movement of the car and on its controllability, and on front-wheel models compensates the resulting kinematic changes of geometry of a suspension bracket determined by influence of force of draft. At zero convergence the distance between forward edges of wheels is equal to distance between their rear edges.
Convergence of forward wheels
Disorder is called the wheel tilt angle in relation to a paving in the vertical plane. If the top part of a wheel is inclined to an axis of symmetry of the car, disorder is called negative and vice versa. Correctness of adjustment of disorder determines the size and the provision of a spot of contact of protectors with a paving and allows to compensate the changes in suspension bracket geometry happening during commission of turns and at the movement of the car on an uneven paving.
Angles of installation of a wheel
Kinematic length of a pin represents the shortest distance between the center of the operated wheel and an axis of its turn.
Shoulder of stabilization is called the distance between a point of contact of a wheel and a point of intersection of an axis of its turn with a paving on a side view determining the size of the stabilizing moment and influencing course stability of the car and distribution of forces in steering at commission of turns.
Vybegom is called a corner of a longitudinal inclination of an axis of turn of a wheel, i.e., corner between an axis of turn and a vertical on a side view. Together with a corner of a cross inclination of an axis выбег exerts impact on change of disorder of wheels at measurement of an angle of rotation of a steering wheel, and also on the stabilizing moment.
The shoulder of a running in decides as distance between a point of contact of a wheel with a paving and a point of intersection of an axis of its turn on a paving on the front view. The shoulder is considered negative when the last from the points called above is between the center and the top part of a wheel. Parameter exerts impact on extent of influence of forces of braking on a steering wheel and on size of the stabilizing moment, and, negative shoulder of a running in increases the last.
The corner of a cross inclination of an axis of turn of a wheel represents a corner between an axis of turn of a wheel and a vertical in the plane of cross section of the car. Along with vybegy and the size of longitudinal shift of an axis of turn exerts impact on sensitivity of steering.
Conditions of check of angles of installation of wheels
Check of angles of installation of the car demands existence of specially equipped platform. Before check it is necessary to make sure of performance of the following conditions:
- Air pressure in tires corresponds to nominal;
- Forward wheels are established rectilinearly;
- The car is not loaded, fuel tank is completely filled;
- Osazhena car suspension bracket elements with effort;
- The steering drive correctly is adjusted;
- Side plays in wheel bearings, tips of steering drafts and spherical support of a suspension bracket do not go beyond admissible limits;
- Depth of a protector of the tires installed on wheels of one axis is identical.