AN outstanding feature relevant to the consideration of shaft whip phenomena is that intermediate bearings cannot be depended upon to eliminate whip by reducing the free shaft length, for under these conditions the forces tending to produce whip are still present and are transmitted to the bearings in the form of shocks which are likely to coincide with the maximum inertia load positions and result in overloading. Apart from this, an absolutely rigid bearing supporting structure is a practical impossibility (even if it were desirable) and flexing of the shaft is inevitably communicated to the structure so that if this be excessive, vibration, fatigue and rapid general deterioration must result.