CEMB USA C88 (A) User Manual
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5.7 - Eccentricity measurement
The much enlarged fi gures show the outer tyre surface and axis of wheel rotation.
Fig. A - shows measurement of the total Peak-to-Peak eccentricity defi ned as maximum radial deviation of the tyre
surface.
►
Fig. B - shows measurement of the eccentricity of the 1st
harmonic, i.e. the eccentricity of that circle which “recopies”
the tyre shape, by averaging the local deviations of the
tyre from the round shape.
Obviously the P.P. measurement is normally greater than
that of the 1st harmonic. Tyre manufacturers normally
supply two different tolerances for the two eccentrici-
ties.
The radial and lateral eccentricity measurements are automatically carried out after the unbalance measurement
without having to go into particular procedures. Remember to position the sonar sensors in front of the surface to be
measured before pressing the
button.
The maximum limit of the fi rst harmonic can be set (
FIRST HARMONIC LIMIT
). When this limit is exceeded,
the wheel balancer displays the red symbol above the
button to indicate an eccentricity condition that
needs to be corrected.