ROLLER BEARING FAILURES IN REDUCTION GEAR
~by Herbert Roeser, Trans Marine Propulsion Systems, Inc.
Flexible couplings provide a convenient means for modifying and improving the natural frequency characteristics of a system, often having significant damping effect under resonant conditions. The ability to reduce resonant vibration amplitudes is usually confined to modes of vibration having dominant relative angular deflections across the coupling elements, since the actual damping torque is proportional to the rate of change of angular displacement in the coupling. This means that the frequency of the vibration has a large effect on the damping torque in an elastic coupling. This is the reason why the lower order vibrations are more difficult to dampen out. The power loss in the coupling is related to the amount of damping provided by the coupling. Due to this, it is often necessary to tune the system such that there is no resonant condition within the operating range of the system that can be excited by the low engine orders. If this is not accomplished, low order vibration amplitudes can be transmitted to the reduction gears by the coupling due to insufficient damping at resonance condition.Read the entire article
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