The power impulses of an engine tend to set up torsional vibration in the crankshaft.
If this torsional vibration were not controlled, the crankshaft might actually break at
certain speeds; a vibration damper mounted on the front of the crankshaft controls this
There are a
few variations of the vibration damper (fig. 3-44), but they all accomplish their task
basically in the same manner. They all use a two-piece design The differences in design
are in how the two pieces are linked together. One type of damper links the pieces
together by an adjustable friction clutch. Whenever a suddenchange in crankshaft speed
occurs, it causes the friction clutch to slip. This is because the outer section of the
damper tends to continue at the same speed. The slippage of the clutch acts to absorb the
torsional vibration. Another type of damper links the two pieces together with rubber. As
the crankshaft speeds up, the rubber compresses, storing energy. This minimizes the effect
of crankshaft speed increase. As the crankshaft unwinds, the damper releases energy stored
in the compressed rubber to cushion the speed change in the other direction.