The term dynamometer is commonly defined as – “an instrument for measuring mechanical force”, with force being commonly defined as – “any external agent that causes a change in the motion of a free body, or that causes stress in a fixed body”. In the case of the chassis dyno, the purpose at hand is to measure the rotational force of the driven wheels mounted to the vehicle under test. This is typically achieved via a series of rollers - which when coupled to a vehicle’s tires resembles a toothless gear arrangement. In many cases, an absorption device is incorporated into the roller arrangement so as to allow for “steady state” testing. It's true that any chassis dyno can spin your wheels and do some calculations, but only a Mustang dyno can give you a real world simulation every time. Our patented control system uses eddy current power absorbers to load a vehicle exactly the way it would be loaded on the street -- including wind resistance, which is a significant factor in high-speed testing. Mustang dynos also feature a load cell to measure the power being applied to the rolls. Without going into a lot of theory, a Mustang dyno gives you a real world tune, every time.