Sympathetic Oscillation

A number of years ago, one of the major auto companies experienced a large scale problem with steering column shake in vehicles with a new 4-cylinder engine. It turned out that at idle; a stop light for example, the engine’s natural frequency was the same as the steering column assembly. The steering wheel would begin sympathetic oscillation and the driver would suffer with wheel shake.

The most common image of this resonance is the tuning fork. Bang one tuning fork and put it near another tuning fork of the same frequency and it will begin to vibrate too.
This is the same phenomenon that allows a powerful singing voice to break a delicate wine glass by producing sound waves at the natural, or resonant, frequency of the glass. Continue reading