The Merrill Wheel-Balancing System was the world's first electronic dynamic wheel-balancing system. It was invented in 1945 by Marcellus Merrill at the Merrill Engineering Laboratories, 2390 South Tejon Street, Englewood, Colorado

Englewood, Colorado

The city of Englewood is a Home Rule Municipality located in Arapahoe County, Colorado, United States. As of 2007, the city is estimated to have a total population of 32,532. Englewood is part of the Denver-Aurora Metropolitan Area. Englewood is located in the South Platte River Valley east of the...

, and is now recorded on the list of IEEE Milestones in electronic engineering

Electronic engineering

Electronics engineering, also referred to as electronic engineering, is an engineering discipline where non-linear and active electrical components such as electron tubes, and semiconductor devices, especially transistors, diodes and integrated circuits, are utilized to design electronic...

 and as an American Society of Mechanical Engineers

American Society of Mechanical Engineers

The American Society of Mechanical Engineers is a professional body, specifically an engineering society, focused on mechanical engineering....

 landmark.

Before Merrill's invention, all wheel-balancing for automobiles, trucks, etc., required removal of the wheel from the vehicle. Most required some form of static balancing without wheel rotation, which was slow and error prone.

Merrill's invention balanced wheels while still mounted to the vehicle, by spinning them at high speed and electronically analyzing the vibrations to trigger a stroboscope

Stroboscope

A stroboscope, also known as a strobe, is an instrument used to make a cyclically moving object appear to be slow-moving, or stationary. The principle is used for the study of rotating, reciprocating, oscillating or vibrating objects...

. Technicians could then determine where balancing weights should be added.