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12.6. Suspension bracket geometry

The angles of installation of wheels of the car - the general information

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.

The listed below kinematic installations of wheel assemblies in relation to steering and transfer of forces between tires and a paving are the most important. It is necessary to remember that 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 of the Head Podvesk and steering.

Convergence (convergence) is called the corner between the lines formed at section by the horizontal plane of the following planes:

Convergence of forward wheels

δvs — the Corner of a convergence of wheels
and — Distance between forward edges of wheels
b — Distance between the rear edges of wheels
s — the Track
b-and — Convergence

Convergence can be also defined as a difference of distances between extreme lobbies and the rear edges of wheel assemblies. 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. Normal convergence usually does not exceed inch shares (1 inch = 2.54 cm).

Disorder is called the corner between the lines formed at section by the vertical plane, the perpendicular plane of symmetry of the car of the following planes:

Angles of installation of a wheel

M — the Center of wheel assembly
rst — the Kinematic length of a pin
nζ — the Longitudinal shift of an axis of turn of a wheel
n — the Positive shoulder of stabilization
ζ — the Corner of a longitudinal inclination of an axis of turn of a wheel
rσ — the Cross shift of an axis of turn of a wheel
rs — a running in Shoulder
Υ — the Corner of disorder of wheels
σ — the Corner of a cross inclination of an axis of turn of a wheel

If the top part of a wheel is rejected from an axis of symmetry of the car outside, 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.

Kinematic length of a pin represents the shortest distance between the center of the operated wheel and an axis of its turn. For all-wheel drive cars this parameter characterizes influence of forces of draft and forces of resistance to swing on controllability of the vehicle.

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., a 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 change of an angle of rotation of a steering wheel, and also influences 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, the 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.

The general check of geometry of a suspension bracket is made at the special stand in the conditions of a specialized workshop.

Back wheels of the car have the suspension brackets which are not giving in to adjustment zero corners of disorder and a vybeg determined by geometry. The description of procedures of check and adjustment of angles of installation of forward wheels of the car is provided in the Section Check and adjustment of angles of installation of forward wheels.

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: