JOSAM laser AM
Measuring system
39
Adjusting
screw and
lock nut
Center point
Centering of the steering box
Checking the center point of the steering box
when it is not marked.
On a steering box with an adjusting screw and lock
nut, one can look for the center point.
Hang the frame gauges, gauge extensions and
measuring scales.
Jack up the axle.
Attach the wheel adapter and laser projector.
Compensate for run-out of the wheel with the
adjustment knobs on the adapter.
Loosen the lock nut and tighten the adjustment
screw until resistance is felt when the wheel is
turned by hand back and forth over the center point.
Tighten the lock nut.
This adjustment is easier to perform with the AM
TOOL SET.
Aim the laser projector at the front measuring
scale. Turn the wheel by hand from the inside
and out toward the middle until light resistance is
felt. Read the value on the measuring scale. For
example: 130. Turn the wheel then from the
outside and in toward the middle until light
resistance is felt. Read the value on the measuring
scale. For example: 100.
The center point is 115, which is halfway
between 130 and 100.
Position the wheel with the laser dot on the front
measuring scale A at 115.
Aim the laser projector at the rear measuring scale B.
If the values are the same on both measuring scales,
the center point of the steering box corresponds with
the straight ahead position of the wheel.
If the values on the measuring scales A and B do
not agree, check the deviation.
The normal deviation between the center point of
the steering box and the straight ahead position of
the wheel is 1
°
per meter, 1
°
= 17. 5 mm per m.
If the deviation is more than 1
°
/m, the length of the
steering linkage should be adjusted so that the
center point on the steering box corresponds with
the straight ahead position of the wheel.
Adjust the play in the steering box with the
adjusting screw until no resistance is felt when the
wheel is turned by hand over the center point.
The wheel must be possible to turn without feeling
resistance.
