CEMB USA C65 (E) - Manual (Page 20)

I 0206 - 20 GB
5.6 - ECCENTRICITY MEASUREMENT (OPTIONAL)
The much enlarged figures show the outer tyre surface and axis of wheel rotation.
Fig. A shows measurement of the total Peak-to-Peak eccentricity defined 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 eccentricities.
GRAPH 1 : represents the actual Peak-to-Peak eccentricity.
GRAPH 2 : represents the eccentricity of the 1st harmonic. For a wheel in optimum conditions, such graph
should approach a straight line.
When the wheel is moved, the cursor on the screen indicates the actual value, with the phase referred
to the eccentricity measurement sensor.
GRAPH 1 - (yellow)
GRAPH 2 - (red)
At the end of the balancing spin it is possible to automatically measure the eccentricity of the tyre
through the SONAR sensor installed on the guard. The sensor should be positioned by hand in front
of the tyre tread.