Transcript Wheel Balance Theory Balance - Unbalance What does it mean? Balance....by definition The stability resulting from the equalization of opposing forces. Equal Force.

Wheel Balance Theory
Balance - Unbalance
What does it mean?
1
Balance....by definition
The stability resulting from the
equalization of opposing forces.
Equal Force
2
Types of imbalance...
Static
Single Plane
Dynamic
Two Plane
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What is Static Balance?
Static Balance is when the
weight of the wheel and tire
assembly is distributed
equally around the axis of the
wheel rotation.
If static Balance exists the
wheel will have no tendency
to rotate.
If rotated it rotates with
Equal Force
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How do you Static Balance this Wheel?
Heavy Area Rotates to Bottom
.25 oz Imbalance
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Is this wheel in static balance?
.25 oz imbalance
.25 oz weight added
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...and, if this wheel is in static balance?
If this wheel is in perfect balance at a speed
of 40 mph, will it remain in balance at all
speeds?
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The answer: yes, BUT... can you Prove it?
At 20 mph .25 oz of imbalance generates
.86 pounds of force
.86 lbs
.86 lbs
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At 70 mph the force is 10.53 pounds
It's still in perfect balance!
10.53 lbs
NOTE: Speed rated Tires
Utilize a Nylon Over-lay to
prevent tire distortion at
high speeds.
10.53
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One common problem:
Improper use of equipment
Mounting Method
Clean Mounting Surface
Calibration
Careless Weight Placement
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Consider this...
Most Computer Wheel Balancers Round off to the nearest .25 oz.
1 oz. Balance Weight
1.12 oz. Imbalance
Is this a Problem?
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Is this “rounding off..” a Problem?
On most cars, this slight imbalance would NOT be felt.
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BUT, some Customers......
Complain about a Vibration at one Speed!
Why?
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...vibration at one speed!
is why a Vibration may occur at one
particular Speed!
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Natural Frequency
Mechanical Objects have there own
Natural Frequency
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Tire & Wheel "Natural Frequency"
4 Revolutions = Frequency of 4
CPS/HZ
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Tire & Wheel Frequency Change with Speed
Tire imbalance frequency increasing
Vehicle Speed
Increasing
17
Suspension Natural Frequency
Range from 10 - 15 Hz/CPS
14 Hz
12 Hz
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Beating - & - Phasing
Suspension Frequency
Tire & Wheel Frequency
Sum of the two above
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The point at which it is felt...
15
10
5
0
10
20
30 40
50
60
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...and, the complaint...
"...but, I balanced the tires in the
FINE/NON-ROUND-OFF mode and...
...it still vibrates at 55 M.P.H.
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What's the Problem?
Mounting Error
Are wheels centered by the center hole?
Hub-centric
Are wheels centered by the lug nuts... or...
Lug-centric
Duplicate O.E.M. Mounting
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...also, Consider this
Are Tires and Wheels Perfectly Round?
Tire High Spot
Wheel
High
Spot
Would this Mismatch cause a problem?
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15
10
5
0
10
20
30 40
50
60
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Match Mounting
Mis-Matched
Matched
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Dynamic / 2-Plane
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Dynamic Imbalance
1 oz. Imbalance
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During one revolution
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