By " steering wheel turn routine " is to understand the reciprocal steering turn routine of the front wheels. It is a standard for the indirect measurement of Caster, king pin angle and track difference angle.
Usually the steering angle takes place by operator control; first to the right than to the left from the straight-ahead position, then; finally the wheels are set straight ahead.
The driving angle is the angle between the geometric driving axle and the vehicle longitudinal centre level .
The driving angle is positive, if the geometric driving axle deviates to the left from the vehicle longitudinal centre line. The driving angle results of toe, side disalignment and bevelling of the rear axle.
Depending on optimal assembling and adjustment of the chassis the driving angle
is zero; otherwise the vehicle induces itself more or less diagonally with travelling
straight ahead to its symmetry axis. This is called also " Dackel-Lauf (small
dogs kind of running)" and is recognizable with travelling straight ahead
from the more or less inclined-standing steering wheel.
The " travel straight ahead" is an help position of the steering element, with which the two front axle single track values are aligned to same value regarding to the vehicle longitudinal centre line.
This adjustment takes place with the modern measuring computer by operator control; the exact position of the steering wheel is not evaluated here yet. In the help position " travel straight ahead " the toe and camber values of the rear axle are measured.
The execution of the wheel runout compensation aims at electronically to enter
and to compensate for the measurement of track and camber the lateral run out
of the rim and the stretching error of sensor spanner or Quick span unit during
measurement on a wheel.
For a precise chassis measurement with close toe and camber tolerances the wheel runout compensation is mandatory necessarily, only when using vehicle brand-specific quick-clamping units may it be omitted.