Harmonic damper

A harmonic damper is a device connected to the free end of the crankshaft of an internal combustion engine. It is needed in engines with long crankshafts, such as straight-8 engines. It is used on most engines to reduce torsional vibrations that can occure at certain speeds.
Construction.
The damper consists of an inner hub attached to the end of the crankshaft. A round mass is attached to the hub by an elastic material. This becomes a spring-mass-damper system. By selection of the damping material and the size of the mass, the damper can be made to quiet the torsional vibrations. The overall appearance is that of a thick disk.