COATS 6200HS Truck Wheel Balancer - Manual (Page 28)

22
Coats Model 6200HS
Wheel Mounting Errors
Regardless of the mounting method used, the wheel
must be centered before balancing. A wheel should be
mounted on the appropriate cone or adaptor and
tightened carefully to ensure proper centering and mating
against the balancer flange.
The wheel must be clean and free of large burrs or
nicks, especially where it mates with the cone or
adaptor and the balancer flange. Any dirt between the
flange and the mating surface of the wheel will cause
misalignment on the shaft. A misalignment of the
thickness of a matchbook cover will cause an
unbalance of 15 grams (0.50 ounce) or more on
automobile wheels and 30 grams (1 ounce) on light
truck wheels.
The wheel must also be tightened securely to prevent
it from slipping in relation to the flange. If the wheel
slips on the balancer, accurate weight measurement
and location are impossible.
Wheel Rotational Errors
When a wheel is mounted on the balancer, whether
using a cone or an adaptor, it is fixed in a particular
position in relation to the balancer shaft. If the wheel is
rotated 180 degrees from the initial position and
retightening, a different balance reading may result. Such
differences are called rotational errors.
When checking balance with the wheel in one position
and then rotating it 180 degrees and re-spinning it, the
difference between the two readings could be as much
as 15 grams (0.50 ounce) for cone-mounted automobile
wheels, and 60 grams (2 ounces) for light truck wheels.
The actual balance error is one-half of the displayed
amount because the reading is the sum of the error
and the weight required to counterbalance the error.
To do a rotational test, first fine-balance the wheel.
Then loosen the wheel on the shaft, rotate it 180
degrees, and retighten the handle. Spin the wheel in
the normal mode to check for rotational errors.