Ref.: WB-VL-65 DSP LX Premium - OM Ver.1.6 (B2927)
12
5. OPERATING PRINCIPLE
5.1.
UNBALANCE OF WHEEL
In normal condition unevenly worn out tyre causes uneven mass (weight)
distribution
with respect to wheel centre. Even Brand new tyres may have small amount of uneven
mass distribution i.e., Unbalance.
When the wheel is in motion, the unbalanced mass causes a centrifugal force. This
force when meeting the road squeezes the tyre momentarily.
This force is directly proportional to speed square (F N
2
) ie., as the speed increases,
the force increases in square proportion causing patch wear of the tyre. An unbalance
in Front wheels, will give a vibration that can be felt through the steering wheel. At high
speeds, the effect can be felt more. Unbalance in the rear wheels will result in a
vibration that can be felt through the vehicle body. This unbalance can have a
detrimental effect on the various joints and suspension of the vehicle.
To eliminate the unbalance, balancing of the wheel has to be carried out. Balancing is
the process of finding out the „Mass‟ which causes unbalance and the location (phase)
of the mass, and adding equal weight in the directly opposite location (180º away).
Fig. 7
5.2.
STATIC BALANCING (Single plane balancing)
Static balancing is the process of adding equal amount of balancing weight at 180º
position opposite to the position of the Unbalance. Static balancing is applicable only
for thin wheels of less than 3” width (Motorcycle Wheels). Normally the unbalanced
weight will be added on the rim of the wheels though the unbalance may be anywhere
in the width as shown in Fig.8. To get perfect balancing the weight must be added in
the same plane at 180º opposite position (Inner position).
In Static balancing Method, though the weight is not added in the same plane, the
Dynamic forces caused will be very minimal when the wheel width is small. But in the
case of wider wheels, the distance between the plane of unbalance and the plane of
the weight addition will be more and for this reason a Force couple will be formed and it
will create a rocking effect on the bearings of the wheels. This kind of situation
requires a Dynamic balancing technique.
Fig. 8
