In tire shops and automotive repair shops throughout the country, there are three kinds of tire balancers. Listed below are three types and a brief explanation of how they work.
Tire balancers that are static are mostly obsolete these days. Even so, tire manufacturers still use them to ensure that the unbalance inherent in every tire is within tolerance. Balancers of this type work by sensing only what angle off the center line contains the unbalanced portion. Grass causes a cone the tire sits on to deflect in that direction.
There is a glycerin-filled chamber with an air bubble on top of the cone. The air bubble will deflect in the opposite direction of the imbalance. A sensor’s deflection will determine whether it complies with specifications. In shops that still employ older, more traditional mechanics, this type of balancer is still available.
Dynamic On-the-Car Spin Balancing
This is the most accurate, but most dangerous method of tire balancing. There is no need to remove the tire and wheel, and their position is maintained on the car by placing a ‘hat’ on the wheel. A wheeled motor is placed against the tire, causing it to spin. A hat contains balance mechanisms for determining where an unbalanced situation arises.
Six friction rings protrude from the snout of the hat. The technician holds the friction rings lightly, while resting a hand on the fender, moving weights inside the hat. Vibrations will be minimized when the most ideal combination of inner and outer weights is achieved. The technician then reads the display, which displays weights graphically, and applies the weights as specified.
Typically, he will spin the tire once more to ensure that he has done it correctly. By choosing the appropriate weights and positioning, the least amount of vibration will result, and both inner and outer indicators will read zero or close to zero. The tire and wheel are spun on the car during this type of balancing, allowing for any vehicle-specific issues to be taken into account, such as an off center lug pattern or hub.
Dynamic High Speed Spin Balancing
Most tire balancing machines these days look like this. To balance the tire and wheel combination, a set of cups is used to center the hub and a locking handle. From the side of the machine, the technician enters the rim width and diameter as well as the offset and presses the start button.
The machine spins the tire up to operating speeds of about 60 MPH. A calibrated shaft runs into the balancer and holds the tire. This machine contains a computer that detects the deflection and location of any imbalance in the tire and displays the results on an LED display with lights that move vertically to indicate where weights are to be placed.
The amount of weight needed is displayed digitally. When the weights are applied, the technician spins the wheel one more time to ensure proper weight placement.
Tire balancing beads are a new technology that has recently gained public acceptance. These are small ceramic or steel beads that migrate to the opposite side of the tire from any unbalanced areas, thereby counteracting the imbalance.