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Automatic balancing of a rigid rotor with misaligned shaft

Research output: Working paperWorking paper and Preprints

Original languageEnglish
Publication dateMay 2006


We present a nonlinear analysis of the dynamics of an automatic ball balancer (ABB) for rotors which are both eccentric and misaligned. The ABB consists of two or more ball bearings which are free to travel around a circular race at a fixed distance from the shaft. The balls, after a transient response, find a steady state which balances the rotor. Following the previous work of Green et al. at Bristol, we have included the effect of shaft misalignment which causes the rotor to precess. This can be countered by having two ABB races at different axial locations along the shaft. Mathematically, we use a Lagrangian approach to derive the equations of motion for the system. It is found that, contrary to the case of flexible rotors that are subject to eccentricity and shaft bending, there is no choice of co-ordinate system which leads to autonomous governing equations. Simulations are then computed which illustrate the role of the ball damping coefficient.

Additional information

Sponsorship: EPSRC, Rolls-Royce plc.

Research areas

  • Euler angles, automatic balancing, shaft misalignment, rigid rotor



  • Preprint

    Preprint (usually an early version) , 275 KB, PDF-document

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  1. Automatic balancing of a rigid rotor with misaligned shaft

    Research output: Chapter in Book/Report/Conference proceedingConference contribution