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LAUNCH
Correct Kingpin Inclination can equalize the loads
applied on bearings so that the life of bearings can
be prolonged and the controllability of steering is
improved.
Without the inclination, the controllability of the
steering may be affected; further more, the vehicle
weight and the ground counterforce may cause
significant stress in the axle and finally damage the
axle.
Correct inclination of king pin is also helpful for the
vehicle to restore its straight-ahead position after
steering.
Kingpin Inclination is determined when the vehicle
suspension is designed. It is not service adjustable.
Caster
Caster is the tilting of the kingpin either forwards or
backwards from vertical, as viewed from side of the
vehicle. See Fig.1.4
When the king pin is tilted backwards from the
vertical, caster is positive. When the king pin is tilted
KWA-300 3D Wheel Aligner
Fig.1.3
Fig.1.4
forwards, caster is negative.
Caster angle influences the directional stability of
the steering. To increase the tendency of the
steering to self-centre, the steering will normally be
designed with positive caster.
Toe-out on Turns
Toe-out on turns is defined as the difference of the
steering angle between the two front wheels when
turning left or right by 20°as shown in Figure 1.5.
The inner wheel will turn more degrees than the
outer wheel when the vehicle is steered, the
difference is usually about 2°. This angle is
designed to reduce steering resistance.
Note: This angle can be tested when a turntable
is equipped for KWA-300 3D.
Thrust angle
The trust angle is defined according to the driven
mode of vehicle.
l Rear wheel driven: the thrust angle equals half
of the toe-in difference between the two rear
wheels. As shown in Fig.1.6.
l Front wheel driven: the thrust angle equals half
of the toe-in difference between the two front
wheels.
l Four-wheel driven: the thrust angle equals half
of the toe-in difference between the two front
wheels plus half of the toe-in difference
between the two rear wheels.
The trust angle is defined as positive when the trust
line is towards left, and negative when the line is
towards right.
If the thrust angle is not zero, the vehicle will have
the side-moving trend. In this case, adjust the front
1-2
Introduction
Fig.1.5
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