GILLIG LOW FLOOR, Руководство по обслуживанию

Страница: 300 / 506

Brakes & Wheels
300
Wheel and Tire Balancing
It is desirable from the standpoint of tire wear and coach handling to maintain the proper balance of
front wheel and tire assemblies. All wheels intended for use on the front wheels, such as those switched
during tire rotation and those installed as new or repaired replacements, should be accurately balanced.
This may be accomplished by two types of procedures: “On Vehicle” or “Off Vehicle.” The “On Ve -
hicle” is more desirable, however, because all the rolling components (drums, bearings, seals, etc.) are
included in the balancing procedure and, therefore, any existing unbalanced condition is corrected.
Wheel balance is the equal distribution of weight of the wheel and tire assembly around the axis of rota -
tion. Wheels can be balanced “Statically” and “Dynamically.” Wheels must be balanced statically first
and then dynamically.
Static Balance
Static balancing is also called “still” balancing. It is the equal balance of the weight of the wheel and
tire around the axis of rotation so that the assembly has no tendency to rotate by itself, regardless of its
position. Static unbalance causes a hopping or pounding action (up and down) which frequently leads to
wheel flutter or wheel tramp.
Dynamic Balance
An out-of-round condition greater than 3/32" (2.4 mm) cannot be
corrected with balancing. Such an assembly is not suitable for installation
on the front axle of a coach. Check for this condition as described earlier
in this manual.
Dynamic balance is also called “running” balance. It means the wheel must be in static balance and also
run smoothly at all speeds on an axis which turns through the center line of the wheel and is perpendicu-
lar to the axis of rotation.
To ensure successful and accurate balancing, the following precautions must be attended to.
• The wheel and tire must be clean and free from all foreign matter. The tires should be in good con-
dition and properly mounted with the balance mark on the tire, if any, aligned with the valve.
• Bent wheels which have runout over 3/32" (2.4 mm) should be discarded or straightened before
balancing.
• Use of wheels on the rear axle should be governed by the condition of the assembly and whether
the roundness defect affects the quality of the ride.
• When balancing wheels and tires, it is recommended that the instructions and procedures covering
the wheel balancer be followed closely.