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The suspension geometry

Corners of installation of wheels of the car - the general information

The suspension geometry and its rigidity is determined by the possibility of limiting the vertical movements of the body and reduce the angular oscillations about the lateral and longitudinal axes.

The front wheels rotate around the inclined axis, whose position is determined by the hinges and suspension car parts.

The most important are the following kinematic installation of wheel assemblies with respect to the steering wheel and the transmission of forces between the tires and the road surface. It should be remembered that the angles of the wheels greatly affect the stability of the car, tire wear and fuel consumption. The nominal value to be checked and wheel alignment described in this guide are given in the Car Specifications Chapter Suspension and steering.

Convergence (convergence) is the angle between the lines formed by the horizontal cross-sectional plane of the following planes:

• The plane of symmetry of the vehicle;
• The plane of the wheel rim.

Toe-in

δ vs - toe angle and - distance between the front edges of the wheels b - The distance between the rear edges of the wheels s - Track b-a - Convergence

Convergence can also be defined as the difference in distance between the extreme front and rear edges of the wheel assemblies. Convergence affects the straightness of the car and its handling, and front-wheel drive models compensates for the resulting kinematic change the suspension geometry, determines the effect of traction. At zero convergence distance between the front edges of the wheels is equal to the distance between their rear edges. Normal convergence is not usually exceed a fraction of an inch (1 inch = 2.54 cm).

Lounging is the angle between the lines formed by the vertical plane of section perpendicular to the plane of symmetry of the vehicle following planes:

• The plane of symmetry of the vehicle;
• The plane of the wheel rim.

Wheel alignment

M - The center of the wheel assembly r st - Kinematic length of the trunnion n ζ - Longitudinal offset of the axis of rotation wheel n - Positive shoulder stabilization ζ - Corner of a longitudinal inclination of the axis of rotation wheel r σ - Lateral displacement of the axis of rotation of the wheel r s - Shoulder running Υ - camber σ - cross angle of inclination of the axis of rotation of the wheel

If the upper part of the wheel deviates from the axis of symmetry of the car outside, he called the collapse of the negative, and vice versa. A correct control of the collapse determines the amount and position of the contact patch with the road surface protectors, and to compensate for changes in suspension geometry that occur during cornering and when driving over uneven pavement.

Kinematic stud length is the shortest distance between the center of steerable wheel and the axis of its rotation. For the four-wheel drive, this parameter characterizes the influence of the forces of traction and rolling resistance forces in the handling of the vehicle.

Shoulder stabilization is the distance between the contact point of the wheel and the point of intersection of the axis of rotation of the road surface in a side of the stabilizing torque determines the magnitude and influence the stability of the vehicle and the distribution of forces in the steering when making turns.

Coasting is the angle of inclination of the longitudinal axis of rotation of the wheel, i.e., the angle between the vertical axis of rotation and in a side view. At the angle of inclination of the transverse axis of the stick affects camber change when changing the steering angle and also affects the stabilizing moment.

Kingpin offset is defined as the distance between the point of wheel contact with the road surface and the intersection of its rotation axis with the road surface in a front view. Shoulder considered negative when the last of the above points is between the center and the upper portion of the wheel. The parameter affects the degree of impact deceleration forces on the steering wheel and on the value of stabilizing moment, and, negative kingpin offset increases last.

The angle of inclination of the transverse axis of rotation wheel is an angle between the axis of rotation of the wheels and a vertical cross-sectional plane of the vehicle. Apart from coasting and the longitudinal displacement axis of rotation influences the steering sensitivity.

General check suspension geometry is carried out on a special stand in a specialized workshop.

The rear wheels of the car are determined by the geometry of the suspension can not be adjusted camber angles and zero coasting. Description of the procedures for verification and alignment of the front wheels of the car resulted in Section Check and adjustment of corners of installation of forward wheels.

Terms of checking wheel alignment

Check alignment of the car requires a specially equipped rack. Before you start scanning, you must ensure the following conditions:

• Tyre pressure corresponds to the nominal;
• The front wheels are mounted in a straight line;
• The car is loaded, the fuel tank is completely filled;
• Suspension elements Car upset with the effort;
• Steering gear properly adjusted;
• Play in the wheel bearings, tie rods and ball bearings suspension does not go beyond the limits;
• The depth of the tread of tires mounted on the wheels of one same axle.