If you've ever seen an automobile crankshaft up-close and personal, you know that it's a big, heavy, and extremely tough piece of equipment. It has to be, in order to withstand the pounding it takes from the thousands of explosive piston strokes it receives per minute.
Tough as it is, a crankshaft is prone to twisting and flexing in reaction to the drubbing it takes from the pistons and connecting rods above it. It can also transmit unwanted vibration throughout the engine and rest of the vehicle. Furthermore, at a certain RPM, the crankshaft can reach a state called resonance, where it vibrates at a frequency that can cause catastrophic failure (think of the television commercials you've seen where a resonant singer or high-pitched sound is used to shatter an unlucky wine glass).
In 1911, automotive genius Frederick Lanchester invented a device to bolt onto the end of spinning crankshafts to eliminate, or at least reduce these problems. The harmonic balancer (which goes by names including vibration damper/dampener, or crankshaft pulley) was born. This balancer dampens the shearing, twisting forces imparted on the crankshaft by the pushing of the pistons. To absorb the tremendous energy of the crankshaft, the balancer has a section that can be made of rubber or filled with an energy-dissipating fluid [source: Hillier].
So far, we've looked at lots of ways to passively prevent, or at least muffle, those annoying engine vibrations. But our last anti-vibration innovation actually goes on the attack to keep those bad vibes at bay.