ASME-Landmark:Merrill Wheel Balancing System

Marcellus Merrill first implemented an electronic dynamic wheel-balancing system in 1945. Prior to the development of this system, automobile wheels had to be removed from the vehicle for static balancing (without rotating). Mr. Merrill came up with the idea of balancing the tire and wheel while they were still mounted on the car. To do this, with the wheel jacked off the ground he would spin the tire and wheel at high speed, and then analyze the resultant vibrations as the wheel coasted to lower speeds. The vibrations were monitored by an electronic pickup, which sat on the floor and was attached to the bumper of the car by a magnet on the end of a probe. The signal was used to trigger a stroboscopic light which made the wheel appear to stand still. This light identified the point at which the balance weight should be added. The signal also helped to establish the amount of weight to be added to effect a proper balance. If the wheel to be balanced were a front wheel, it was spun by a "spinner" which consisted of an electric motor with a large flat pulley which was pressed against the wheel. If a rear wheel were to be balanced, only one rear wheel was jacked up and it was spun with the automobile's engine.

This system was developed for balancing crankshafts of high-speed racing car engines and later for use by General Electric Company for 2,000 to 3,000 pound rotors. Elements of Merrill's dynamic balancing systems are still used today, primarily for industrial and automotive production applications. See ASME website for more information