CEMB USA C75-L (C) - Manual (Page 24)

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SOLUTION:
Rotate the tyre on the rim by 180°
Example 3
Rim 0 mm
Tyre + 1.2 mm
Wheel + 1,2 mm
Eccentricity of the wheel cannot be
compensated by the rotation because
the rim is perfect!
wheel
rim
tyre
rotation axle
Ideal wheel
RESULT:
no improvement is obtained
5.7.1 - Presetting of tolerance on the machine
There is no general rule concerning acceptability of an eccentricity value . As a first approximation we consider it cor-
rect to use a threshold of 1 to 1.5 mm. The E/ECE/324 standard prescribes 1.5 mm as max. eccentricity of a rebuilt
tyre.
5.7.2 - Value of static unbalance, correlated with eccentricity
Clear indication is given in the Measurement screen of both the value and position of the static unbalance as well
as the eccentricity. In fact, it is interesting to check the correlations of the two values, above all of the two positions.
When the two positions have a similar angle (± 30° one from the other), there is a
clear sign that an eccentricity is
present which can be compensated by matching.
5.7.3 - Value of unbalance corresponding to eccentricity
For user’s reference, the centrifugal force is calculated corresponding to a certain speed, compared to the force
generated by the eccentricity present on the tyre (calculated with an approximate average elastic constant).