They are usually in the form of a round metal plate mounted in some manner to the wheel assembly, with a tube filled ball bearings, shot, sand, oil or mercury forming a ring around the outer perimeter. Some wheel balancers are hub mounted, and some are actually in the form of a tire fluid. The only criteria for location is that they become an integral part of the wheel assembly. The wheel assembly may consist of two or even three tires. All the wheels are locked together through the tire lugs.
Corrections made by the balancer are for the entire assembly.
Only one balancer is needed per assembly regardless of whether it is one, two or three tires. This does not apply to static wheel balancers. In this case, each tire must be separatelybalanced. Using Murcury as the Active Element Balance Masters of Northridge, Califomia, is the only company that uses mercury as the balancing liquid. The ball did not bounce at all due to the counter force created by the liquid, opposing the attempted upward thrust of the ball.