wheel balance theory
DESCRIPTION
Wheel Balance Theory. Balance - Unbalance What does it mean?. Balance.... by definition. The stability resulting from the equalization of opposing forces. Equal Force. Types of imbalance. Static Single Plane Dynamic Two Plane. What is Static Balance?. - PowerPoint PPT PresentationTRANSCRIPT
1
Wheel Balance Theory
Balance - UnbalanceWhat does it mean?
2
Balance....by definition
The stability resulting from the equalization of opposing forces.
Equal Force
3
Types of imbalance...
StaticSingle Plane
DynamicTwo Plane
4
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
5
How do you Static Balance this Wheel?
Heavy Area Rotates to Bottom
.25 oz Imbalance
6
Is this wheel in static balance?
.25 oz imbalance .25 oz weight added
7
...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?
8
The answer: yes, BUT... can you Prove it?
At 20 mph .25 oz of imbalance generates .86 pounds of force
.86 lbs
.86 lbs
9
At 70 mph the force is 10.53 pounds
It's still in perfect balance!
10.53 lbs
10.53NOTE: Speed rated Tires Utilize a Nylon Over-lay to prevent tire distortion at high speeds.
10
One common problem:
Improper use of equipmentMounting Method
Clean Mounting Surface
Calibration
Careless Weight Placement
11
Consider this...
1.12 oz. Imbalance
Most Computer Wheel Balancers Round off to the nearest .25 oz.
1 oz. Balance Weight
Is this a Problem?
12
Is this “rounding off..” a Problem?
On most cars, this slight imbalance would NOT be felt.
13
BUT, some Customers......
Complain about a Vibration at one Speed!
Why?
14
...vibration at one speed!
is why a Vibration may occur at one particular Speed!
15
Natural Frequency
Mechanical Objects have there own Natural Frequency
16
Tire & Wheel "Natural Frequency"
4 Revolutions = Frequency of 4 CPS/HZ
17
Tire & Wheel Frequency Change with Speed
Vehicle Speed Increasing
Tire imbalance frequency increasing
18
Suspension Natural Frequency
14 Hz
12 Hz
Range from 10 - 15 Hz/CPS
19
Beating - & - Phasing
Suspension Frequency
Tire & Wheel Frequency
Sum of the two above
20
The point at which it is felt...
15
10
5
0 10 20 30 40 50 60
21
...and, the complaint...
"...but, I balanced the tires in the FINE/NON-ROUND-OFF mode and...
...it still vibrates at 55 M.P.H.
22
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
23
...also, Consider this
Are Tires and Wheels Perfectly Round?Tire High Spot
Wheel High Spot
Would this Mismatch cause a problem?
24
15
10
5
0 10 20 30 40 50 60
25
Match Mounting
Mis-Matched Matched
26
Dynamic / 2-Plane
27
Dynamic Imbalance
1 oz. Imbalance
28
During one revolution