Accu-Turn 1250, Service Manual, Page: 61 / 85

M 0494 -
14
I E
a
b
h
GB
11 - WHEEL MEASUREMENT AND PRESETTING ON THE BALANCING MACHINE
The ever increasing need for more accurate calibration and use of the ALU functions means that it is important to esta-
blish how to measure the rims and how the balancing machine interprets the preset data. Hence a description is now
given of how to modify the preset dimensions automatically in order to obtain the distances of the correction planes
which are defined as through planes for the centres of gravity of the corrective weights.
Consider a typical rim: size “
l
” , given as width by the rim manufacturer, differs from the measurement of the distance
between the correction planes for the rim thickness and physical dimensions of the counterweight, whose centre of
gravity is located at distance “h” from the resting point of the rim edge.
The balancing machine automatically corrects the measurement preset by adding 2 x h = 6 mm to the measurement.
Measurement “b” made with the gauge is generally more accurate even if very similar to the measurement “
l
” known to
the rim user. The two measurements differ only by the thickness of the sheet metal, usually about 2 mm per side. Such
insignificant distance means that an accurate calibration can be obtained regardless of whether the inner rim with “
l
”
or outer width “b” is preset. It is a good rule to add ¼ inch to the value given by the manufacturer. As regards the ALU
functions, the machine performs the following approximations in addition to the systematic correction regarding the
centre of gravity of the counterweight as seen above.
N.B.:
I = INSIDE
E = OUTSIDE
a = a preset - 8 mm
b = b preset - 11 mm
dI = d preset
dE = dI
a = a preset - 3 mm
b = b preset - 16 mm
dI = d preset
dE = dI - 1”
a = a preset - 8 mm
b = b 11 mm
dI = d preset
dE = dI + 1”
ALUM
a = aI preset - 8 mm
b = aE - aI
dI = dI preset
dE = dI - 1”
ALUM VARIANT
a = aI preset - 3 mm
b = (aE - aI) - 5 mm
dI = dI preset
dE = dI - 2"
0 gauge
(First notch)
0 gauge
(First notch)