Ref.: MEL-WA(3D HCV) - OM Ver.1.7
25
5.14.
TOE OUT ON TURNS
When the front wheels of a vehicle are steered to left or right, the angle turned by each
wheel at any instant is not equal. When the left wheel is turned towards left side by 20°
from the Straight ahead position the right side wheel would have turned lesser than
20°. If the Toe is measured at this instant, it will always be in „Toe-out‟ condition.
Fig. 22
The difference between the angle turned by left and right wheel is responsible for the
Toe-out condition.
Let a = the angle turned by left wheel. i.e., the angle made by the rear axle centre
line produced and a line drawn perpendicular to the plane of the left wheel
from its centre.
Let b = the angle turned by right wheel. i.e., the angle made by the rear axle centre
line produced and a line drawn perpendicular to the plane of the right wheel
from its centre.
(a - b) = r
L
is the difference in angle turned by left and right wheels.
Similarly when the right front wheel is turned 20° towards right side, the left side wheel
would have turned less than 20° because of the Ackerman principle employed in the
steering system.
The difference in angle turned by the front wheels during left turns (r
L
) and right turns
(r
R
) should be equal or within allowable tolerance.
If r
L
& r
R
are not equal or not within limits, then it indicates
i.
Bent Steering link
ii.
Wrong positioning of pitman arm in the Steering box
iii.
Not centralizing the rack in the steering box in the straight ahead position
